* [PATCH V9 01/17] rust: cpumask: Use non-atomic helpers
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 15:20 ` Yury Norov
2025-04-11 10:55 ` [PATCH V9 02/17] rust: cpumask: Add few more helpers Viresh Kumar
` (15 subsequent siblings)
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Yury Norov,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
The cpumask Rust abstractions don't need the atomic variants of helpers
for now. Use the non-atomic helpers instead.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/helpers/cpumask.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
index 2d380a86c34a..ae964cddbd41 100644
--- a/rust/helpers/cpumask.c
+++ b/rust/helpers/cpumask.c
@@ -2,14 +2,14 @@
#include <linux/cpumask.h>
-void rust_helper_cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
+void rust_helper___cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
{
- cpumask_set_cpu(cpu, dstp);
+ __cpumask_set_cpu(cpu, dstp);
}
-void rust_helper_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
+void rust_helper___cpumask_clear_cpu(int cpu, struct cpumask *dstp)
{
- cpumask_clear_cpu(cpu, dstp);
+ __cpumask_clear_cpu(cpu, dstp);
}
void rust_helper_cpumask_setall(struct cpumask *dstp)
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 01/17] rust: cpumask: Use non-atomic helpers
2025-04-11 10:55 ` [PATCH V9 01/17] rust: cpumask: Use non-atomic helpers Viresh Kumar
@ 2025-04-11 15:20 ` Yury Norov
0 siblings, 0 replies; 31+ messages in thread
From: Yury Norov @ 2025-04-11 15:20 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:00PM +0530, Viresh Kumar wrote:
> The cpumask Rust abstractions don't need the atomic variants of helpers
> for now. Use the non-atomic helpers instead.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> rust/helpers/cpumask.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
> index 2d380a86c34a..ae964cddbd41 100644
> --- a/rust/helpers/cpumask.c
> +++ b/rust/helpers/cpumask.c
> @@ -2,14 +2,14 @@
>
> #include <linux/cpumask.h>
>
> -void rust_helper_cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
> +void rust_helper___cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
> {
> - cpumask_set_cpu(cpu, dstp);
> + __cpumask_set_cpu(cpu, dstp);
> }
>
> -void rust_helper_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
> +void rust_helper___cpumask_clear_cpu(int cpu, struct cpumask *dstp)
> {
> - cpumask_clear_cpu(cpu, dstp);
> + __cpumask_clear_cpu(cpu, dstp);
> }
Please just add non-atomic helpers after atomic ones.
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 02/17] rust: cpumask: Add few more helpers
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 01/17] rust: cpumask: Use non-atomic helpers Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 03/17] rust: cpumask: Add initial abstractions Viresh Kumar
` (14 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Yury Norov,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Add few more cpumask helpers that are required by the Rust abstraction.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/helpers/cpumask.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
index ae964cddbd41..30fc0bc0c0e8 100644
--- a/rust/helpers/cpumask.c
+++ b/rust/helpers/cpumask.c
@@ -12,11 +12,26 @@ void rust_helper___cpumask_clear_cpu(int cpu, struct cpumask *dstp)
__cpumask_clear_cpu(cpu, dstp);
}
+bool rust_helper_cpumask_test_cpu(int cpu, struct cpumask *srcp)
+{
+ return cpumask_test_cpu(cpu, srcp);
+}
+
void rust_helper_cpumask_setall(struct cpumask *dstp)
{
cpumask_setall(dstp);
}
+bool rust_helper_cpumask_empty(struct cpumask *srcp)
+{
+ return cpumask_empty(srcp);
+}
+
+bool rust_helper_cpumask_full(struct cpumask *srcp)
+{
+ return cpumask_full(srcp);
+}
+
unsigned int rust_helper_cpumask_weight(struct cpumask *srcp)
{
return cpumask_weight(srcp);
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 03/17] rust: cpumask: Add initial abstractions
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 01/17] rust: cpumask: Use non-atomic helpers Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 02/17] rust: cpumask: Add few more helpers Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 15:54 ` Yury Norov
2025-04-11 10:55 ` [PATCH V9 04/17] MAINTAINERS: Add entry for Rust cpumask API Viresh Kumar
` (13 subsequent siblings)
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Yury Norov, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Burak Emir,
Rasmus Villemoes, Russell King, linux-clk, Michael Turquette,
linux-kernel
Add initial Rust abstractions for struct cpumask, covering a subset of
its APIs. Additional APIs can be added as needed.
These abstractions will be used in upcoming Rust support for cpufreq and
OPP frameworks.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/cpumask.rs | 328 +++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
2 files changed, 329 insertions(+)
create mode 100644 rust/kernel/cpumask.rs
diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs
new file mode 100644
index 000000000000..a9d22c1d7a5a
--- /dev/null
+++ b/rust/kernel/cpumask.rs
@@ -0,0 +1,328 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! CPU Mask abstractions.
+//!
+//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h)
+
+use crate::{
+ alloc::{AllocError, Flags},
+ bindings,
+ prelude::*,
+ types::Opaque,
+};
+
+#[cfg(CONFIG_CPUMASK_OFFSTACK)]
+use core::ptr::{self, NonNull};
+
+#[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+use core::mem::MaybeUninit;
+
+use core::ops::{Deref, DerefMut};
+
+/// A CPU Mask.
+///
+/// Rust abstraction for the C `struct cpumask`.
+///
+/// # Invariants
+///
+/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
+///
+/// The callers must ensure that the `struct cpumask` is valid for access and remains valid for the
+/// lifetime of the returned reference.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to update a [`Cpumask`].
+///
+/// ```
+/// use kernel::bindings;
+/// use kernel::cpumask::Cpumask;
+///
+/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) {
+/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the
+/// // returned reference.
+/// let mask = unsafe { Cpumask::from_raw_mut(ptr) };
+///
+/// mask.set(set_cpu);
+/// mask.clear(clear_cpu);
+/// }
+/// ```
+#[repr(transparent)]
+pub struct Cpumask(Opaque<bindings::cpumask>);
+
+impl Cpumask {
+ /// Creates a mutable reference to an existing `struct cpumask` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ /// Creates a reference to an existing `struct cpumask` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Obtain the raw `struct cpumask` pointer.
+ pub fn as_raw(&self) -> *mut bindings::cpumask {
+ self as *const _ as _
+ }
+
+ /// Set `cpu` in the cpumask.
+ ///
+ /// Equivalent to the kernel's `__cpumask_set_cpu` API.
+ #[inline]
+ pub fn set(&mut self, cpu: u32) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
+ unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Clear `cpu` in the cpumask.
+ ///
+ /// Equivalent to the kernel's `__cpumask_clear_cpu` API.
+ #[inline]
+ pub fn clear(&mut self, cpu: i32) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to
+ // `__cpumask_clear_cpu`.
+ unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Test `cpu` in the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_test_cpu` API.
+ #[inline]
+ pub fn test(&self, cpu: i32) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`.
+ unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) }
+ }
+
+ /// Set all CPUs in the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_setall` API.
+ #[inline]
+ pub fn setall(&mut self) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`.
+ unsafe { bindings::cpumask_setall(self.as_raw()) };
+ }
+
+ /// Checks if cpumask is empty.
+ ///
+ /// Equivalent to the kernel's `cpumask_empty` API.
+ #[inline]
+ pub fn empty(&self) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`.
+ unsafe { bindings::cpumask_empty(self.as_raw()) }
+ }
+
+ /// Checks if cpumask is full.
+ ///
+ /// Equivalent to the kernel's `cpumask_full` API.
+ #[inline]
+ pub fn full(&self) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`.
+ unsafe { bindings::cpumask_full(self.as_raw()) }
+ }
+
+ /// Get weight of the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_weight` API.
+ #[inline]
+ pub fn weight(&self) -> u32 {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`.
+ unsafe { bindings::cpumask_weight(self.as_raw()) }
+ }
+
+ /// Copy cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_copy` API.
+ #[inline]
+ pub fn copy(&self, dstp: &mut Self) {
+ // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`.
+ unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
+ }
+}
+
+/// A CPU Mask pointer.
+///
+/// Rust abstraction for the C `struct cpumask_var_t`.
+///
+/// # Invariants
+///
+/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`.
+///
+/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid
+/// for the lifetime of [`CpumaskVar`].
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create and update a [`CpumaskVar`].
+///
+/// ```
+/// use kernel::cpumask::CpumaskVar;
+///
+/// let mut mask = CpumaskVar::new(GFP_KERNEL).unwrap();
+///
+/// assert!(mask.empty());
+/// mask.set(2);
+/// assert!(mask.test(2));
+/// mask.set(3);
+/// assert!(mask.test(3));
+/// assert_eq!(mask.weight(), 2);
+///
+/// let mask2 = CpumaskVar::try_clone(&mask).unwrap();
+/// assert!(mask2.test(2));
+/// assert!(mask2.test(3));
+/// assert_eq!(mask2.weight(), 2);
+/// ```
+pub struct CpumaskVar {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: NonNull<Cpumask>,
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ mask: Cpumask,
+}
+
+impl CpumaskVar {
+ /// Creates an initialized instance of the [`CpumaskVar`].
+ pub fn new(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
+ // that, it is always safe to call this method.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
+ // scope.
+ unsafe { bindings::zalloc_cpumask_var(&mut ptr, _flags.as_raw()) };
+ NonNull::new(ptr.cast()).ok_or(AllocError)?
+ },
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ // SAFETY: FFI type is valid to be zero-initialized.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
+ mask: unsafe { core::mem::zeroed() },
+ })
+ }
+
+ /// Creates an uninitialized instance of the [`CpumaskVar`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
+ /// getting used.
+ unsafe fn new_uninit(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
+ // that, it is always safe to call this method.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
+ // scope.
+ unsafe { bindings::alloc_cpumask_var(&mut ptr, _flags.as_raw()) };
+ NonNull::new(ptr.cast()).ok_or(AllocError)?
+ },
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
+ mask: unsafe { MaybeUninit::uninit().assume_init() },
+ })
+ }
+
+ /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ /// Creates a reference to an existing `struct cpumask_var_t` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Clones cpumask.
+ pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
+ // SAFETY: The returned cpumask_box is initialized right after this call.
+ let mut cpumask_box = unsafe { Self::new_uninit(GFP_KERNEL) }?;
+
+ cpumask.copy(&mut cpumask_box);
+ Ok(cpumask_box)
+ }
+}
+
+// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`].
+impl Deref for CpumaskVar {
+ type Target = Cpumask;
+
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref(&self) -> &Self::Target {
+ // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
+ unsafe { &*self.ptr.as_ptr() }
+ }
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ fn deref(&self) -> &Self::Target {
+ &self.mask
+ }
+}
+
+impl DerefMut for CpumaskVar {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref_mut(&mut self) -> &mut Cpumask {
+ // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
+ unsafe { self.ptr.as_mut() }
+ }
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ fn deref_mut(&mut self) -> &mut Cpumask {
+ &mut self.mask
+ }
+}
+
+impl Drop for CpumaskVar {
+ fn drop(&mut self) {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`.
+ unsafe {
+ bindings::free_cpumask_var(self.as_raw())
+ };
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index de07aadd1ff5..75f78f6bfaa6 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -42,6 +42,7 @@
pub mod block;
#[doc(hidden)]
pub mod build_assert;
+pub mod cpumask;
pub mod cred;
pub mod device;
pub mod device_id;
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 03/17] rust: cpumask: Add initial abstractions
2025-04-11 10:55 ` [PATCH V9 03/17] rust: cpumask: Add initial abstractions Viresh Kumar
@ 2025-04-11 15:54 ` Yury Norov
2025-04-14 11:29 ` Viresh Kumar
0 siblings, 1 reply; 31+ messages in thread
From: Yury Norov @ 2025-04-11 15:54 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:02PM +0530, Viresh Kumar wrote:
> Add initial Rust abstractions for struct cpumask, covering a subset of
> its APIs. Additional APIs can be added as needed.
>
> These abstractions will be used in upcoming Rust support for cpufreq and
> OPP frameworks.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> rust/kernel/cpumask.rs | 328 +++++++++++++++++++++++++++++++++++++++++
> rust/kernel/lib.rs | 1 +
> 2 files changed, 329 insertions(+)
> create mode 100644 rust/kernel/cpumask.rs
>
> diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs
> new file mode 100644
> index 000000000000..a9d22c1d7a5a
> --- /dev/null
> +++ b/rust/kernel/cpumask.rs
> @@ -0,0 +1,328 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! CPU Mask abstractions.
> +//!
> +//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h)
> +
> +use crate::{
> + alloc::{AllocError, Flags},
> + bindings,
> + prelude::*,
> + types::Opaque,
> +};
> +
> +#[cfg(CONFIG_CPUMASK_OFFSTACK)]
> +use core::ptr::{self, NonNull};
> +
> +#[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> +use core::mem::MaybeUninit;
> +
> +use core::ops::{Deref, DerefMut};
> +
> +/// A CPU Mask.
> +///
> +/// Rust abstraction for the C `struct cpumask`.
> +///
> +/// # Invariants
> +///
> +/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
> +///
> +/// The callers must ensure that the `struct cpumask` is valid for access and remains valid for the
This line is too long to me.
> +/// lifetime of the returned reference.
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to update a [`Cpumask`].
> +///
> +/// ```
> +/// use kernel::bindings;
> +/// use kernel::cpumask::Cpumask;
> +///
> +/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) {
> +/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the
> +/// // returned reference.
> +/// let mask = unsafe { Cpumask::from_raw_mut(ptr) };
> +///
> +/// mask.set(set_cpu);
> +/// mask.clear(clear_cpu);
> +/// }
> +/// ```
> +#[repr(transparent)]
> +pub struct Cpumask(Opaque<bindings::cpumask>);
> +
> +impl Cpumask {
> + /// Creates a mutable reference to an existing `struct cpumask` pointer.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
> + /// of the returned reference.
> + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &mut *ptr.cast() }
> + }
> +
> + /// Creates a reference to an existing `struct cpumask` pointer.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
> + /// of the returned reference.
> + pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask) -> &'a Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &*ptr.cast() }
> + }
> +
> + /// Obtain the raw `struct cpumask` pointer.
> + pub fn as_raw(&self) -> *mut bindings::cpumask {
> + self as *const _ as _
> + }
> +
> + /// Set `cpu` in the cpumask.
> + ///
> + /// Equivalent to the kernel's `__cpumask_set_cpu` API.
> + #[inline]
> + pub fn set(&mut self, cpu: u32) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
> + unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) };
> + }
> +
> + /// Clear `cpu` in the cpumask.
> + ///
> + /// Equivalent to the kernel's `__cpumask_clear_cpu` API.
Similarly to bitmaps, can you explain here that this is a non-atomic
operation?
> + #[inline]
> + pub fn clear(&mut self, cpu: i32) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to
> + // `__cpumask_clear_cpu`.
> + unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) };
> + }
> +
> + /// Test `cpu` in the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_test_cpu` API.
> + #[inline]
> + pub fn test(&self, cpu: i32) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`.
> + unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) }
> + }
> +
> + /// Set all CPUs in the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_setall` API.
> + #[inline]
> + pub fn setall(&mut self) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`.
> + unsafe { bindings::cpumask_setall(self.as_raw()) };
> + }
> +
> + /// Checks if cpumask is empty.
> + ///
> + /// Equivalent to the kernel's `cpumask_empty` API.
> + #[inline]
> + pub fn empty(&self) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`.
> + unsafe { bindings::cpumask_empty(self.as_raw()) }
> + }
> +
> + /// Checks if cpumask is full.
> + ///
> + /// Equivalent to the kernel's `cpumask_full` API.
> + #[inline]
> + pub fn full(&self) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`.
> + unsafe { bindings::cpumask_full(self.as_raw()) }
> + }
> +
> + /// Get weight of the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_weight` API.
> + #[inline]
> + pub fn weight(&self) -> u32 {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`.
> + unsafe { bindings::cpumask_weight(self.as_raw()) }
> + }
> +
> + /// Copy cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_copy` API.
> + #[inline]
> + pub fn copy(&self, dstp: &mut Self) {
> + // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`.
> + unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
> + }
> +}
> +
> +/// A CPU Mask pointer.
> +///
> +/// Rust abstraction for the C `struct cpumask_var_t`.
> +///
> +/// # Invariants
> +///
> +/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`.
> +///
> +/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid
> +/// for the lifetime of [`CpumaskVar`].
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to create and update a [`CpumaskVar`].
> +///
> +/// ```
> +/// use kernel::cpumask::CpumaskVar;
> +///
> +/// let mut mask = CpumaskVar::new(GFP_KERNEL).unwrap();
> +///
> +/// assert!(mask.empty());
> +/// mask.set(2);
> +/// assert!(mask.test(2));
> +/// mask.set(3);
> +/// assert!(mask.test(3));
> +/// assert_eq!(mask.weight(), 2);
> +///
> +/// let mask2 = CpumaskVar::try_clone(&mask).unwrap();
> +/// assert!(mask2.test(2));
> +/// assert!(mask2.test(3));
> +/// assert_eq!(mask2.weight(), 2);
> +/// ```
> +pub struct CpumaskVar {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: NonNull<Cpumask>,
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + mask: Cpumask,
> +}
> +
> +impl CpumaskVar {
> + /// Creates an initialized instance of the [`CpumaskVar`].
> + pub fn new(_flags: Flags) -> Result<Self, AllocError> {
> + Ok(Self {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: {
> + let mut ptr: *mut bindings::cpumask = ptr::null_mut();
> +
> + // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
> + // that, it is always safe to call this method.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
> + // scope.
> + unsafe { bindings::zalloc_cpumask_var(&mut ptr, _flags.as_raw()) };
> + NonNull::new(ptr.cast()).ok_or(AllocError)?
> + },
> +
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + // SAFETY: FFI type is valid to be zero-initialized.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
> + mask: unsafe { core::mem::zeroed() },
> + })
> + }
> +
> + /// Creates an uninitialized instance of the [`CpumaskVar`].
I would do this another way: introduce new() that calls
alloc_cpumask_var(), and new_zero() binded to zalloc() version. Your
statement here is simply wrong because I can pass GFP_ZERO and 'hack'
all your architecture.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
> + /// getting used.
> + unsafe fn new_uninit(_flags: Flags) -> Result<Self, AllocError> {
> + Ok(Self {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: {
> + let mut ptr: *mut bindings::cpumask = ptr::null_mut();
> +
> + // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
> + // that, it is always safe to call this method.
I'm not sure I understand this sentence. What's wrong with safety when
the alloc() function sleeps? Even if something is wrong. If you really
want to protect your users, you'd introduce new_sync() version that
returns error if user provides sleeping flags.
To that extend, once you write so many flavors of constructors, I bet
your users will be happy if you hide the 'flags' entirely:
new_gfp(flags);
new();
new_zero(); // or znew()?
new_sync();
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
> + // scope.
> + unsafe { bindings::alloc_cpumask_var(&mut ptr, _flags.as_raw()) };
> + NonNull::new(ptr.cast()).ok_or(AllocError)?
> + },
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
> + mask: unsafe { MaybeUninit::uninit().assume_init() },
> + })
> + }
> +
> + /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
> + /// of the returned reference.
> + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
The 'from' (wrt cpumasks) has a special meaning: search for a cpu
starting from a given one. This 'from_raw' may confuse readers. Have
you any other name for it in mind?
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &mut *ptr.cast() }
> + }
> +
> + /// Creates a reference to an existing `struct cpumask_var_t` pointer.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
> + /// of the returned reference.
> + pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &*ptr.cast() }
> + }
> +
> + /// Clones cpumask.
> + pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
Just clone(), I think.
> + // SAFETY: The returned cpumask_box is initialized right after this call.
> + let mut cpumask_box = unsafe { Self::new_uninit(GFP_KERNEL) }?;
> +
> + cpumask.copy(&mut cpumask_box);
> + Ok(cpumask_box)
> + }
> +}
> +
> +// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`].
> +impl Deref for CpumaskVar {
> + type Target = Cpumask;
> +
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + fn deref(&self) -> &Self::Target {
> + // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
> + unsafe { &*self.ptr.as_ptr() }
> + }
> +
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + fn deref(&self) -> &Self::Target {
> + &self.mask
> + }
> +}
> +
> +impl DerefMut for CpumaskVar {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + fn deref_mut(&mut self) -> &mut Cpumask {
> + // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
> + unsafe { self.ptr.as_mut() }
> + }
> +
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + fn deref_mut(&mut self) -> &mut Cpumask {
> + &mut self.mask
> + }
> +}
> +
> +impl Drop for CpumaskVar {
> + fn drop(&mut self) {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`.
> + unsafe {
> + bindings::free_cpumask_var(self.as_raw())
> + };
> + }
> +}
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index de07aadd1ff5..75f78f6bfaa6 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -42,6 +42,7 @@
> pub mod block;
> #[doc(hidden)]
> pub mod build_assert;
> +pub mod cpumask;
> pub mod cred;
> pub mod device;
> pub mod device_id;
> --
> 2.31.1.272.g89b43f80a514
^ permalink raw reply [flat|nested] 31+ messages in thread* Re: [PATCH V9 03/17] rust: cpumask: Add initial abstractions
2025-04-11 15:54 ` Yury Norov
@ 2025-04-14 11:29 ` Viresh Kumar
0 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-14 11:29 UTC (permalink / raw)
To: Yury Norov, Danilo Krummrich, Miguel Ojeda
Cc: Rafael J. Wysocki, Miguel Ojeda, Alex Gaynor, Boqun Feng,
Gary Guo, Björn Roy Baron, Benno Lossin, Andreas Hindborg,
Alice Ryhl, Trevor Gross, Danilo Krummrich, linux-pm,
Vincent Guittot, Stephen Boyd, Nishanth Menon, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Burak Emir, Rasmus Villemoes,
Russell King, linux-clk, Michael Turquette, linux-kernel
On 11-04-25, 11:54, Yury Norov wrote:
> On Fri, Apr 11, 2025 at 04:25:02PM +0530, Viresh Kumar wrote:
> > + unsafe fn new_uninit(_flags: Flags) -> Result<Self, AllocError> {
> > + Ok(Self {
> > + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> > + ptr: {
> > + let mut ptr: *mut bindings::cpumask = ptr::null_mut();
> > +
> > + // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
> > + // that, it is always safe to call this method.
>
> I'm not sure I understand this sentence. What's wrong with safety when
> the alloc() function sleeps? Even if something is wrong. If you really
> want to protect your users, you'd introduce new_sync() version that
> returns error if user provides sleeping flags.
I borrowed this SAFETY comment from similar allocation done in
page.rs, I think we can skip it though. Here is the delta so far:
@@ -27,8 +27,8 @@
///
/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
///
-/// The callers must ensure that the `struct cpumask` is valid for access and remains valid for the
-/// lifetime of the returned reference.
+/// The callers must ensure that the `struct cpumask` is valid for access and
+/// remains valid for the lifetime of the returned reference.
///
/// ## Examples
///
@@ -86,7 +86,9 @@ pub fn as_raw(&self) -> *mut bindings::cpumask {
/// Set `cpu` in the cpumask.
///
- /// Equivalent to the kernel's `__cpumask_set_cpu` API.
+ /// ATTENTION: Contrary to C, this Rust `set()` method is non-atomic.
+ /// This mismatches kernel naming convention and corresponds to the C
+ /// function `__cpumask_set_cpu()`.
#[inline]
pub fn set(&mut self, cpu: u32) {
// SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
@@ -95,7 +97,9 @@ pub fn set(&mut self, cpu: u32) {
/// Clear `cpu` in the cpumask.
///
- /// Equivalent to the kernel's `__cpumask_clear_cpu` API.
+ /// ATTENTION: Contrary to C, this Rust `clear()` method is non-atomic.
+ /// This mismatches kernel naming convention and corresponds to the C
+ /// function `__cpumask_clear_cpu()`.
#[inline]
pub fn clear(&mut self, cpu: i32) {
// SAFETY: By the type invariant, `self.as_raw` is a valid argument to
@@ -198,15 +202,14 @@ pub struct CpumaskVar {
}
impl CpumaskVar {
- /// Creates an initialized instance of the [`CpumaskVar`].
- pub fn new(_flags: Flags) -> Result<Self, AllocError> {
+ /// Creates a zero-initialized instance of the [`CpumaskVar`].
+ pub fn new_zero(_flags: Flags) -> Result<Self, AllocError> {
Ok(Self {
#[cfg(CONFIG_CPUMASK_OFFSTACK)]
ptr: {
let mut ptr: *mut bindings::cpumask = ptr::null_mut();
- // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
- // that, it is always safe to call this method.
+ // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
//
// INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
// scope.
@@ -222,20 +225,19 @@ pub fn new(_flags: Flags) -> Result<Self, AllocError> {
})
}
- /// Creates an uninitialized instance of the [`CpumaskVar`].
+ /// Creates an instance of the [`CpumaskVar`].
///
/// # Safety
///
/// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
/// getting used.
- unsafe fn new_uninit(_flags: Flags) -> Result<Self, AllocError> {
+ unsafe fn new(_flags: Flags) -> Result<Self, AllocError> {
Ok(Self {
#[cfg(CONFIG_CPUMASK_OFFSTACK)]
ptr: {
let mut ptr: *mut bindings::cpumask = ptr::null_mut();
- // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
- // that, it is always safe to call this method.
+ // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
//
// INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
// scope.
> > + /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer.
> > + ///
> > + /// # Safety
> > + ///
> > + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
> > + /// of the returned reference.
> > + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
>
> The 'from' (wrt cpumasks) has a special meaning: search for a cpu
> starting from a given one. This 'from_raw' may confuse readers. Have
> you any other name for it in mind?
'from_raw' is widely used in Rust for similar methods, though I do
understand your concerns.
Danilo / Miguel, what do you suggest I rename these to ?
> > + // SAFETY: Guaranteed by the safety requirements of the function.
> > + //
> > + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
> > + // lifetime of the returned reference.
> > + unsafe { &mut *ptr.cast() }
> > + }
> > + /// Clones cpumask.
> > + pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
>
> Just clone(), I think.
The method 'clone()' is already used by the 'Clone' trait [1], and
that's what I wanted to use initially. But 'clone' doesn't return a
'Result'.
--
viresh
[1] https://doc.rust-lang.org/std/clone/trait.Clone.html
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 04/17] MAINTAINERS: Add entry for Rust cpumask API
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (2 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 03/17] rust: cpumask: Add initial abstractions Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 05/17] rust: clk: Add helpers for Rust code Viresh Kumar
` (12 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Yury Norov, Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Update the MAINTAINERS file to include the Rust abstractions for cpumask
API.
Yury has indicated that he does not wish to maintain the Rust code but
would like to be listed as a reviewer.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
---
MAINTAINERS | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 96b827049501..bd7c54af4fd4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6237,6 +6237,12 @@ L: linux-riscv@lists.infradead.org
S: Maintained
F: drivers/cpuidle/cpuidle-riscv-sbi.c
+CPUMASK API [RUST]
+M: Viresh Kumar <viresh.kumar@linaro.org>
+R: Yury Norov <yury.norov@gmail.com>
+S: Maintained
+F: rust/kernel/cpumask.rs
+
CRAMFS FILESYSTEM
M: Nicolas Pitre <nico@fluxnic.net>
S: Maintained
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 05/17] rust: clk: Add helpers for Rust code
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (3 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 04/17] MAINTAINERS: Add entry for Rust cpumask API Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 06/17] rust: clk: Add initial abstractions Viresh Kumar
` (11 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, Michael Turquette, Stephen Boyd
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Daniel Almeida, linux-kernel
Non-trivial C macros and inlined C functions cannot be used directly
in the Rust code and are used via functions ("helpers") that wrap
those so that they can be called from Rust.
In order to prepare for adding Rust abstractions for the clock APIs,
add clock helpers required by the Rust implementation.
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
MAINTAINERS | 1 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/clk.c | 66 +++++++++++++++++++++++++++++++++
rust/helpers/helpers.c | 1 +
4 files changed, 69 insertions(+)
create mode 100644 rust/helpers/clk.c
diff --git a/MAINTAINERS b/MAINTAINERS
index bd7c54af4fd4..608689342aaf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5883,6 +5883,7 @@ F: include/dt-bindings/clock/
F: include/linux/clk-pr*
F: include/linux/clk/
F: include/linux/of_clk.h
+F: rust/helpers/clk.c
X: drivers/clk/clkdev.c
COMMON INTERNET FILE SYSTEM CLIENT (CIFS and SMB3)
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ab37e1d35c70..f53d6e1a21f2 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -10,6 +10,7 @@
#include <linux/blk-mq.h>
#include <linux/blk_types.h>
#include <linux/blkdev.h>
+#include <linux/clk.h>
#include <linux/cpumask.h>
#include <linux/cred.h>
#include <linux/device/faux.h>
diff --git a/rust/helpers/clk.c b/rust/helpers/clk.c
new file mode 100644
index 000000000000..6d04372c9f3b
--- /dev/null
+++ b/rust/helpers/clk.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/clk.h>
+
+/*
+ * The "inline" implementation of below helpers are only available when
+ * CONFIG_HAVE_CLK or CONFIG_HAVE_CLK_PREPARE aren't set.
+ */
+#ifndef CONFIG_HAVE_CLK
+struct clk *rust_helper_clk_get(struct device *dev, const char *id)
+{
+ return clk_get(dev, id);
+}
+
+void rust_helper_clk_put(struct clk *clk)
+{
+ clk_put(clk);
+}
+
+int rust_helper_clk_enable(struct clk *clk)
+{
+ return clk_enable(clk);
+}
+
+void rust_helper_clk_disable(struct clk *clk)
+{
+ clk_disable(clk);
+}
+
+unsigned long rust_helper_clk_get_rate(struct clk *clk)
+{
+ return clk_get_rate(clk);
+}
+
+int rust_helper_clk_set_rate(struct clk *clk, unsigned long rate)
+{
+ return clk_set_rate(clk, rate);
+}
+#endif
+
+#ifndef CONFIG_HAVE_CLK_PREPARE
+int rust_helper_clk_prepare(struct clk *clk)
+{
+ return clk_prepare(clk);
+}
+
+void rust_helper_clk_unprepare(struct clk *clk)
+{
+ clk_unprepare(clk);
+}
+#endif
+
+struct clk *rust_helper_clk_get_optional(struct device *dev, const char *id)
+{
+ return clk_get_optional(dev, id);
+}
+
+int rust_helper_clk_prepare_enable(struct clk *clk)
+{
+ return clk_prepare_enable(clk);
+}
+
+void rust_helper_clk_disable_unprepare(struct clk *clk)
+{
+ clk_disable_unprepare(clk);
+}
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index e1c21eba9b15..ae595c9cd91b 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -11,6 +11,7 @@
#include "bug.c"
#include "build_assert.c"
#include "build_bug.c"
+#include "clk.c"
#include "cpumask.c"
#include "cred.c"
#include "device.c"
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 06/17] rust: clk: Add initial abstractions
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (4 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 05/17] rust: clk: Add helpers for Rust code Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 07/17] rust: macros: enable use of hyphens in module names Viresh Kumar
` (10 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich,
Michael Turquette, Stephen Boyd, Miguel Ojeda, Alex Gaynor,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Daniel Almeida, linux-kernel
Add initial abstractions for the clk APIs. These provide the minimal
functionality needed for common use cases, making them straightforward
to introduce in the first iteration.
These will be used by Rust based cpufreq / OPP layers to begin with.
Tested-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
MAINTAINERS | 1 +
rust/kernel/clk.rs | 319 +++++++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
3 files changed, 322 insertions(+)
create mode 100644 rust/kernel/clk.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index 608689342aaf..12cde55579a0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5884,6 +5884,7 @@ F: include/linux/clk-pr*
F: include/linux/clk/
F: include/linux/of_clk.h
F: rust/helpers/clk.c
+F: rust/kernel/clk.rs
X: drivers/clk/clkdev.c
COMMON INTERNET FILE SYSTEM CLIENT (CIFS and SMB3)
diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
new file mode 100644
index 000000000000..477daa408587
--- /dev/null
+++ b/rust/kernel/clk.rs
@@ -0,0 +1,319 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Clock abstractions.
+//!
+//! C header: [`include/linux/clk.h`](srctree/include/linux/clk.h)
+//!
+//! Reference: <https://docs.kernel.org/driver-api/clk.html>
+
+use crate::{
+ bindings,
+ device::Device,
+ error::{from_err_ptr, to_result, Result},
+ ffi::c_ulong,
+ prelude::*,
+};
+
+use core::{ops::Deref, ptr};
+
+/// The frequency unit.
+///
+/// Represents a frequency in hertz, wrapping a [`c_ulong`] value.
+///
+/// ## Examples
+///
+/// ```
+/// use kernel::clk::Hertz;
+///
+/// let hz = 1_000_000_000;
+/// let rate = Hertz(hz);
+///
+/// assert_eq!(rate.as_hz(), hz);
+/// assert_eq!(rate, Hertz(hz));
+/// assert_eq!(rate, Hertz::from_khz(hz / 1_000));
+/// assert_eq!(rate, Hertz::from_mhz(hz / 1_000_000));
+/// assert_eq!(rate, Hertz::from_ghz(hz / 1_000_000_000));
+/// ```
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct Hertz(pub c_ulong);
+
+impl Hertz {
+ /// Create a new instance from kilohertz (kHz)
+ pub fn from_khz(khz: c_ulong) -> Self {
+ Self(khz * 1_000)
+ }
+
+ /// Create a new instance from megahertz (MHz)
+ pub fn from_mhz(mhz: c_ulong) -> Self {
+ Self(mhz * 1_000_000)
+ }
+
+ /// Create a new instance from gigahertz (GHz)
+ pub fn from_ghz(ghz: c_ulong) -> Self {
+ Self(ghz * 1_000_000_000)
+ }
+
+ /// Get the frequency in hertz
+ pub fn as_hz(&self) -> c_ulong {
+ self.0
+ }
+
+ /// Get the frequency in kilohertz
+ pub fn as_khz(&self) -> c_ulong {
+ self.0 / 1_000
+ }
+
+ /// Get the frequency in megahertz
+ pub fn as_mhz(&self) -> c_ulong {
+ self.0 / 1_000_000
+ }
+
+ /// Get the frequency in gigahertz
+ pub fn as_ghz(&self) -> c_ulong {
+ self.0 / 1_000_000_000
+ }
+}
+
+impl From<Hertz> for c_ulong {
+ fn from(freq: Hertz) -> Self {
+ freq.0
+ }
+}
+
+/// A reference-counted clock.
+///
+/// Rust abstraction for the C [`struct clk`].
+///
+/// # Invariants
+///
+/// A [`Clk`] instance holds either a pointer to a valid [`struct clk`] created by the C portion of
+/// the kernel or a NULL pointer.
+///
+/// Instances of this type are reference-counted. Calling [`Clk::get`] ensures that the allocation
+/// remains valid for the lifetime of the [`Clk`].
+///
+/// ## Examples
+///
+/// The following example demonstrates how to obtain and configure a clock for a device.
+///
+/// ```
+/// use kernel::c_str;
+/// use kernel::clk::{Clk, Hertz};
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+///
+/// fn configure_clk(dev: &Device) -> Result {
+/// let clk = Clk::get(dev, Some(c_str!("apb_clk")))?;
+///
+/// clk.prepare_enable()?;
+///
+/// let expected_rate = Hertz::from_ghz(1);
+///
+/// if clk.rate() != expected_rate {
+/// clk.set_rate(expected_rate)?;
+/// }
+///
+/// clk.disable_unprepare();
+/// Ok(())
+/// }
+/// ```
+///
+/// [`struct clk`]: https://docs.kernel.org/driver-api/clk.html
+#[repr(transparent)]
+pub struct Clk(*mut bindings::clk);
+
+impl Clk {
+ /// Gets [`Clk`] corresponding to a [`Device`] and a connection id.
+ ///
+ /// Equivalent to the kernel's [`clk_get`] API.
+ ///
+ /// [`clk_get`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get
+ pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
+ let con_id = if let Some(name) = name {
+ name.as_ptr() as *const _
+ } else {
+ ptr::null()
+ };
+
+ // SAFETY: It is safe to call [`clk_get`] for a valid device pointer.
+ //
+ // INVARIANT: The reference-count is decremented when [`Clk`] goes out of scope.
+ Ok(Self(from_err_ptr(unsafe {
+ bindings::clk_get(dev.as_raw(), con_id)
+ })?))
+ }
+
+ /// Obtain the raw [`struct clk`] pointer.
+ #[inline]
+ pub fn as_raw(&self) -> *mut bindings::clk {
+ self.0
+ }
+
+ /// Enable the clock.
+ ///
+ /// Equivalent to the kernel's [`clk_enable`] API.
+ ///
+ /// [`clk_enable`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_enable
+ #[inline]
+ pub fn enable(&self) -> Result {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_enable`].
+ to_result(unsafe { bindings::clk_enable(self.as_raw()) })
+ }
+
+ /// Disable the clock.
+ ///
+ /// Equivalent to the kernel's [`clk_disable`] API.
+ ///
+ /// [`clk_disable`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_disable
+ #[inline]
+ pub fn disable(&self) {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_disable`].
+ unsafe { bindings::clk_disable(self.as_raw()) };
+ }
+
+ /// Prepare the clock.
+ ///
+ /// Equivalent to the kernel's [`clk_prepare`] API.
+ ///
+ /// [`clk_prepare`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_prepare
+ #[inline]
+ pub fn prepare(&self) -> Result {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_prepare`].
+ to_result(unsafe { bindings::clk_prepare(self.as_raw()) })
+ }
+
+ /// Unprepare the clock.
+ ///
+ /// Equivalent to the kernel's [`clk_unprepare`] API.
+ ///
+ /// [`clk_unprepare`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_unprepare
+ #[inline]
+ pub fn unprepare(&self) {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_unprepare`].
+ unsafe { bindings::clk_unprepare(self.as_raw()) };
+ }
+
+ /// Prepare and enable the clock.
+ ///
+ /// Equivalent to calling [`Clk::prepare`] followed by [`Clk::enable`].
+ #[inline]
+ pub fn prepare_enable(&self) -> Result {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for
+ // [`clk_prepare_enable`].
+ to_result(unsafe { bindings::clk_prepare_enable(self.as_raw()) })
+ }
+
+ /// Disable and unprepare the clock.
+ ///
+ /// Equivalent to calling [`Clk::disable`] followed by [`Clk::unprepare`].
+ #[inline]
+ pub fn disable_unprepare(&self) {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for
+ // [`clk_disable_unprepare`].
+ unsafe { bindings::clk_disable_unprepare(self.as_raw()) };
+ }
+
+ /// Get clock's rate.
+ ///
+ /// Equivalent to the kernel's [`clk_get_rate`] API.
+ ///
+ /// [`clk_get_rate`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_rate
+ #[inline]
+ pub fn rate(&self) -> Hertz {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_get_rate`].
+ Hertz(unsafe { bindings::clk_get_rate(self.as_raw()) })
+ }
+
+ /// Set clock's rate.
+ ///
+ /// Equivalent to the kernel's [`clk_set_rate`] API.
+ ///
+ /// [`clk_set_rate`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_set_rate
+ #[inline]
+ pub fn set_rate(&self, rate: Hertz) -> Result {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_set_rate`].
+ to_result(unsafe { bindings::clk_set_rate(self.as_raw(), rate.as_hz()) })
+ }
+}
+
+impl Drop for Clk {
+ fn drop(&mut self) {
+ // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_put`].
+ unsafe { bindings::clk_put(self.as_raw()) };
+ }
+}
+
+/// A reference-counted optional clock.
+///
+/// A lightweight wrapper around an optional [`Clk`]. An [`OptionalClk`] represents a [`Clk`] that
+/// a driver can function without but may improve performance or enable additional features when
+/// available.
+///
+/// # Invariants
+///
+/// An [`OptionalClk`] instance encapsulates a [`Clk`] with either a valid [`struct clk`] or `NULL`
+/// pointer.
+///
+/// Instances of this type are reference-counted. Calling [`OptionalClk::get`] ensures that the
+/// allocation remains valid for the lifetime of the [`OptionalClk`].
+///
+/// ## Examples
+///
+/// The following example demonstrates how to obtain and configure an optional clock for a device.
+/// The code functions correctly whether or not the clock is available.
+///
+/// ```
+/// use kernel::c_str;
+/// use kernel::clk::{OptionalClk, Hertz};
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+///
+/// fn configure_clk(dev: &Device) -> Result {
+/// let clk = OptionalClk::get(dev, Some(c_str!("apb_clk")))?;
+///
+/// clk.prepare_enable()?;
+///
+/// let expected_rate = Hertz::from_ghz(1);
+///
+/// if clk.rate() != expected_rate {
+/// clk.set_rate(expected_rate)?;
+/// }
+///
+/// clk.disable_unprepare();
+/// Ok(())
+/// }
+/// ```
+///
+/// [`struct clk`]: https://docs.kernel.org/driver-api/clk.html
+pub struct OptionalClk(Clk);
+
+impl OptionalClk {
+ /// Gets [`OptionalClk`] corresponding to a [`Device`] and a connection id.
+ ///
+ /// Equivalent to the kernel's [`clk_get_optional`] API.
+ ///
+ /// [`clk_get_optional`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_optional
+ pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
+ let con_id = if let Some(name) = name {
+ name.as_ptr() as *const _
+ } else {
+ ptr::null()
+ };
+
+ // SAFETY: It is safe to call [`clk_get_optional`] for a valid device pointer.
+ //
+ // INVARIANT: The reference-count is decremented when [`OptionalClk`] goes out of scope.
+ Ok(Self(Clk(from_err_ptr(unsafe {
+ bindings::clk_get_optional(dev.as_raw(), con_id)
+ })?)))
+ }
+}
+
+// Make [`OptionalClk`] behave like [`Clk`].
+impl Deref for OptionalClk {
+ type Target = Clk;
+
+ fn deref(&self) -> &Clk {
+ &self.0
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 75f78f6bfaa6..f4dcfefe94be 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -42,6 +42,8 @@
pub mod block;
#[doc(hidden)]
pub mod build_assert;
+#[cfg(CONFIG_COMMON_CLK)]
+pub mod clk;
pub mod cpumask;
pub mod cred;
pub mod device;
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 07/17] rust: macros: enable use of hyphens in module names
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (5 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 06/17] rust: clk: Add initial abstractions Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT() Viresh Kumar
` (9 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Yury Norov, Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, Anisse Astier, linux-kernel
From: Anisse Astier <anisse@astier.eu>
Some modules might need naming that contains hyphens "-" to match the
auto-probing by name in the platform devices that comes from the device
tree.
But rust identifiers cannot contain hyphens, so replace the module name
by an underscore anywhere we'd use it as an identifier.
Signed-off-by: Anisse Astier <anisse@astier.eu>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
[Viresh: Replace "-" with '-', and fix line length checkpatch warnings]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/macros/module.rs | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index a9418fbc9b44..27cc72d474f0 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -185,7 +185,9 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
let info = ModuleInfo::parse(&mut it);
- let mut modinfo = ModInfoBuilder::new(info.name.as_ref());
+ /* Rust does not allow hyphens in identifiers, use underscore instead */
+ let name_identifier = info.name.replace('-', "_");
+ let mut modinfo = ModInfoBuilder::new(name_identifier.as_ref());
if let Some(author) = info.author {
modinfo.emit("author", &author);
}
@@ -310,14 +312,15 @@ mod __module_init {{
#[doc(hidden)]
#[link_section = \"{initcall_section}\"]
#[used]
- pub static __{name}_initcall: extern \"C\" fn() -> kernel::ffi::c_int = __{name}_init;
+ pub static __{name_identifier}_initcall: extern \"C\" fn() ->
+ kernel::ffi::c_int = __{name_identifier}_init;
#[cfg(not(MODULE))]
#[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
core::arch::global_asm!(
r#\".section \"{initcall_section}\", \"a\"
- __{name}_initcall:
- .long __{name}_init - .
+ __{name_identifier}_initcall:
+ .long __{name_identifier}_init - .
.previous
\"#
);
@@ -325,7 +328,7 @@ mod __module_init {{
#[cfg(not(MODULE))]
#[doc(hidden)]
#[no_mangle]
- pub extern \"C\" fn __{name}_init() -> kernel::ffi::c_int {{
+ pub extern \"C\" fn __{name_identifier}_init() -> kernel::ffi::c_int {{
// SAFETY: This function is inaccessible to the outside due to the double
// module wrapping it. It is called exactly once by the C side via its
// placement above in the initcall section.
@@ -335,13 +338,13 @@ mod __module_init {{
#[cfg(not(MODULE))]
#[doc(hidden)]
#[no_mangle]
- pub extern \"C\" fn __{name}_exit() {{
+ pub extern \"C\" fn __{name_identifier}_exit() {{
// SAFETY:
// - This function is inaccessible to the outside due to the double
// module wrapping it. It is called exactly once by the C side via its
// unique name,
- // - furthermore it is only called after `__{name}_init` has returned `0`
- // (which delegates to `__init`).
+ // - furthermore it is only called after `__{name_identifier}_init` has
+ // returned `0` (which delegates to `__init`).
unsafe {{ __exit() }}
}}
@@ -381,6 +384,7 @@ unsafe fn __exit() {{
",
type_ = info.type_,
name = info.name,
+ name_identifier = name_identifier,
modinfo = modinfo.buffer,
initcall_section = ".initcall6.init"
)
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT()
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (6 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 07/17] rust: macros: enable use of hyphens in module names Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 16:07 ` Yury Norov
2025-04-11 10:55 ` [PATCH V9 09/17] rust: cpu: Add from_cpu() Viresh Kumar
` (8 subsequent siblings)
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
The BIT() macro is too complex for Rust's bindgen to interpret as
integer constants. This results in many of the cpufreq macros being
undefined in Rust auto-generated bindings. By replacing the "#define"
macros with an "enum", we ensure that bindgen can properly evaluate
these values, enabling their seamless use in Rust code.
No intentional functional impact.
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
include/linux/cpufreq.h | 96 ++++++++++++++++++++++-------------------
1 file changed, 51 insertions(+), 45 deletions(-)
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 400fee6427a5..354ae35fe708 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -298,11 +298,12 @@ static inline void cpufreq_stats_record_transition(struct cpufreq_policy *policy
* CPUFREQ DRIVER INTERFACE *
*********************************************************************/
-#define CPUFREQ_RELATION_L 0 /* lowest frequency at or above target */
-#define CPUFREQ_RELATION_H 1 /* highest frequency below or at target */
-#define CPUFREQ_RELATION_C 2 /* closest frequency to target */
-/* relation flags */
-#define CPUFREQ_RELATION_E BIT(2) /* Get if possible an efficient frequency */
+enum {
+ CPUFREQ_RELATION_L = 0, /* lowest frequency at or above target */
+ CPUFREQ_RELATION_H = BIT(0), /* highest frequency below or at target */
+ CPUFREQ_RELATION_C = BIT(1), /* closest frequency to target */
+ CPUFREQ_RELATION_E = BIT(2), /* Get if possible an efficient frequency */
+};
#define CPUFREQ_RELATION_LE (CPUFREQ_RELATION_L | CPUFREQ_RELATION_E)
#define CPUFREQ_RELATION_HE (CPUFREQ_RELATION_H | CPUFREQ_RELATION_E)
@@ -424,52 +425,57 @@ struct cpufreq_driver {
/* flags */
-/*
- * Set by drivers that need to update internal upper and lower boundaries along
- * with the target frequency and so the core and governors should also invoke
- * the diver if the target frequency does not change, but the policy min or max
- * may have changed.
- */
-#define CPUFREQ_NEED_UPDATE_LIMITS BIT(0)
+enum {
+ /*
+ * Set by drivers that need to update internal upper and lower
+ * boundaries along with the target frequency and so the core and
+ * governors should also invoke the diver if the target frequency does
+ * not change, but the policy min or max may have changed.
+ */
+ CPUFREQ_NEED_UPDATE_LIMITS = BIT(0),
-/* loops_per_jiffy or other kernel "constants" aren't affected by frequency transitions */
-#define CPUFREQ_CONST_LOOPS BIT(1)
+ /*
+ * loops_per_jiffy or other kernel "constants" aren't affected by
+ * frequency transitions.
+ */
+ CPUFREQ_CONST_LOOPS = BIT(1),
-/*
- * Set by drivers that want the core to automatically register the cpufreq
- * driver as a thermal cooling device.
- */
-#define CPUFREQ_IS_COOLING_DEV BIT(2)
+ /*
+ * Set by drivers that want the core to automatically register the
+ * cpufreq driver as a thermal cooling device.
+ */
+ CPUFREQ_IS_COOLING_DEV = BIT(2),
-/*
- * This should be set by platforms having multiple clock-domains, i.e.
- * supporting multiple policies. With this sysfs directories of governor would
- * be created in cpu/cpu<num>/cpufreq/ directory and so they can use the same
- * governor with different tunables for different clusters.
- */
-#define CPUFREQ_HAVE_GOVERNOR_PER_POLICY BIT(3)
+ /*
+ * This should be set by platforms having multiple clock-domains, i.e.
+ * supporting multiple policies. With this sysfs directories of governor
+ * would be created in cpu/cpu<num>/cpufreq/ directory and so they can
+ * use the same governor with different tunables for different clusters.
+ */
+ CPUFREQ_HAVE_GOVERNOR_PER_POLICY = BIT(3),
-/*
- * Driver will do POSTCHANGE notifications from outside of their ->target()
- * routine and so must set cpufreq_driver->flags with this flag, so that core
- * can handle them specially.
- */
-#define CPUFREQ_ASYNC_NOTIFICATION BIT(4)
+ /*
+ * Driver will do POSTCHANGE notifications from outside of their
+ * ->target() routine and so must set cpufreq_driver->flags with this
+ * flag, so that core can handle them specially.
+ */
+ CPUFREQ_ASYNC_NOTIFICATION = BIT(4),
-/*
- * Set by drivers which want cpufreq core to check if CPU is running at a
- * frequency present in freq-table exposed by the driver. For these drivers if
- * CPU is found running at an out of table freq, we will try to set it to a freq
- * from the table. And if that fails, we will stop further boot process by
- * issuing a BUG_ON().
- */
-#define CPUFREQ_NEED_INITIAL_FREQ_CHECK BIT(5)
+ /*
+ * Set by drivers which want cpufreq core to check if CPU is running at
+ * a frequency present in freq-table exposed by the driver. For these
+ * drivers if CPU is found running at an out of table freq, we will try
+ * to set it to a freq from the table. And if that fails, we will stop
+ * further boot process by issuing a BUG_ON().
+ */
+ CPUFREQ_NEED_INITIAL_FREQ_CHECK = BIT(5),
-/*
- * Set by drivers to disallow use of governors with "dynamic_switching" flag
- * set.
- */
-#define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING BIT(6)
+ /*
+ * Set by drivers to disallow use of governors with "dynamic_switching"
+ * flag set.
+ */
+ CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING = BIT(6),
+};
int cpufreq_register_driver(struct cpufreq_driver *driver_data);
void cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT()
2025-04-11 10:55 ` [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT() Viresh Kumar
@ 2025-04-11 16:07 ` Yury Norov
2025-04-11 17:05 ` Miguel Ojeda
0 siblings, 1 reply; 31+ messages in thread
From: Yury Norov @ 2025-04-11 16:07 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:07PM +0530, Viresh Kumar wrote:
> The BIT() macro is too complex for Rust's bindgen to interpret as
The BIT() is as simple as '1 << nr'. How that it's so complex for that
tool to realize that '1 << 2' is the constant?
> integer constants. This results in many of the cpufreq macros being
> undefined in Rust auto-generated bindings. By replacing the "#define"
> macros with an "enum", we ensure that bindgen can properly evaluate
> these values, enabling their seamless use in Rust code.
>
> No intentional functional impact.
The code you're wiping is perfectly correct. And you clearly state
that one of your tools is broken. Please fix your tool or find any
other solution.
We don't touch correct code, sorry.
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> include/linux/cpufreq.h | 96 ++++++++++++++++++++++-------------------
> 1 file changed, 51 insertions(+), 45 deletions(-)
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 400fee6427a5..354ae35fe708 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -298,11 +298,12 @@ static inline void cpufreq_stats_record_transition(struct cpufreq_policy *policy
> * CPUFREQ DRIVER INTERFACE *
> *********************************************************************/
>
> -#define CPUFREQ_RELATION_L 0 /* lowest frequency at or above target */
> -#define CPUFREQ_RELATION_H 1 /* highest frequency below or at target */
> -#define CPUFREQ_RELATION_C 2 /* closest frequency to target */
> -/* relation flags */
> -#define CPUFREQ_RELATION_E BIT(2) /* Get if possible an efficient frequency */
> +enum {
> + CPUFREQ_RELATION_L = 0, /* lowest frequency at or above target */
> + CPUFREQ_RELATION_H = BIT(0), /* highest frequency below or at target */
> + CPUFREQ_RELATION_C = BIT(1), /* closest frequency to target */
> + CPUFREQ_RELATION_E = BIT(2), /* Get if possible an efficient frequency */
> +};
>
> #define CPUFREQ_RELATION_LE (CPUFREQ_RELATION_L | CPUFREQ_RELATION_E)
> #define CPUFREQ_RELATION_HE (CPUFREQ_RELATION_H | CPUFREQ_RELATION_E)
> @@ -424,52 +425,57 @@ struct cpufreq_driver {
>
> /* flags */
>
> -/*
> - * Set by drivers that need to update internal upper and lower boundaries along
> - * with the target frequency and so the core and governors should also invoke
> - * the diver if the target frequency does not change, but the policy min or max
> - * may have changed.
> - */
> -#define CPUFREQ_NEED_UPDATE_LIMITS BIT(0)
> +enum {
> + /*
> + * Set by drivers that need to update internal upper and lower
> + * boundaries along with the target frequency and so the core and
> + * governors should also invoke the diver if the target frequency does
> + * not change, but the policy min or max may have changed.
> + */
> + CPUFREQ_NEED_UPDATE_LIMITS = BIT(0),
>
> -/* loops_per_jiffy or other kernel "constants" aren't affected by frequency transitions */
> -#define CPUFREQ_CONST_LOOPS BIT(1)
> + /*
> + * loops_per_jiffy or other kernel "constants" aren't affected by
> + * frequency transitions.
> + */
> + CPUFREQ_CONST_LOOPS = BIT(1),
>
> -/*
> - * Set by drivers that want the core to automatically register the cpufreq
> - * driver as a thermal cooling device.
> - */
> -#define CPUFREQ_IS_COOLING_DEV BIT(2)
> + /*
> + * Set by drivers that want the core to automatically register the
> + * cpufreq driver as a thermal cooling device.
> + */
> + CPUFREQ_IS_COOLING_DEV = BIT(2),
>
> -/*
> - * This should be set by platforms having multiple clock-domains, i.e.
> - * supporting multiple policies. With this sysfs directories of governor would
> - * be created in cpu/cpu<num>/cpufreq/ directory and so they can use the same
> - * governor with different tunables for different clusters.
> - */
> -#define CPUFREQ_HAVE_GOVERNOR_PER_POLICY BIT(3)
> + /*
> + * This should be set by platforms having multiple clock-domains, i.e.
> + * supporting multiple policies. With this sysfs directories of governor
> + * would be created in cpu/cpu<num>/cpufreq/ directory and so they can
> + * use the same governor with different tunables for different clusters.
> + */
> + CPUFREQ_HAVE_GOVERNOR_PER_POLICY = BIT(3),
>
> -/*
> - * Driver will do POSTCHANGE notifications from outside of their ->target()
> - * routine and so must set cpufreq_driver->flags with this flag, so that core
> - * can handle them specially.
> - */
> -#define CPUFREQ_ASYNC_NOTIFICATION BIT(4)
> + /*
> + * Driver will do POSTCHANGE notifications from outside of their
> + * ->target() routine and so must set cpufreq_driver->flags with this
> + * flag, so that core can handle them specially.
> + */
> + CPUFREQ_ASYNC_NOTIFICATION = BIT(4),
>
> -/*
> - * Set by drivers which want cpufreq core to check if CPU is running at a
> - * frequency present in freq-table exposed by the driver. For these drivers if
> - * CPU is found running at an out of table freq, we will try to set it to a freq
> - * from the table. And if that fails, we will stop further boot process by
> - * issuing a BUG_ON().
> - */
> -#define CPUFREQ_NEED_INITIAL_FREQ_CHECK BIT(5)
> + /*
> + * Set by drivers which want cpufreq core to check if CPU is running at
> + * a frequency present in freq-table exposed by the driver. For these
> + * drivers if CPU is found running at an out of table freq, we will try
> + * to set it to a freq from the table. And if that fails, we will stop
> + * further boot process by issuing a BUG_ON().
> + */
> + CPUFREQ_NEED_INITIAL_FREQ_CHECK = BIT(5),
>
> -/*
> - * Set by drivers to disallow use of governors with "dynamic_switching" flag
> - * set.
> - */
> -#define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING BIT(6)
> + /*
> + * Set by drivers to disallow use of governors with "dynamic_switching"
> + * flag set.
> + */
> + CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING = BIT(6),
> +};
>
> int cpufreq_register_driver(struct cpufreq_driver *driver_data);
> void cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
> --
> 2.31.1.272.g89b43f80a514
^ permalink raw reply [flat|nested] 31+ messages in thread* Re: [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT()
2025-04-11 16:07 ` Yury Norov
@ 2025-04-11 17:05 ` Miguel Ojeda
0 siblings, 0 replies; 31+ messages in thread
From: Miguel Ojeda @ 2025-04-11 17:05 UTC (permalink / raw)
To: Yury Norov
Cc: Viresh Kumar, Rafael J. Wysocki, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 6:07 PM Yury Norov <yury.norov@gmail.com> wrote:
>
> The BIT() is as simple as '1 << nr'. How that it's so complex for that
> tool to realize that '1 << 2' is the constant?
It is a C macro which requires evaluating a C expression as the C
compiler would.
A solution (a workaround, really) in `bindgen` is coming, that
essentially forces `libclang` to evaluate it for us, but even if it
works perfectly fine already, it will require upgrading the minimum
version and so on, so it will take time.
For the moment, either we do something like this (a similar approach
was used for some `enum`s in Binder) or the values can be replicated
on the Rust side (ideally with a test somewhere to ensure they are in
sync). The latter may be best if the values have not changed much over
time, i.e. if there is low maintenance required.
I hope that helps.
Cheers,
Miguel
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 09/17] rust: cpu: Add from_cpu()
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (7 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 08/17] cpufreq: Use enum for cpufreq flags that use BIT() Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 16:18 ` Yury Norov
2025-04-11 10:55 ` [PATCH V9 10/17] rust: opp: Add initial abstractions for OPP framework Viresh Kumar
` (7 subsequent siblings)
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, Thomas Gleixner, Peter Zijlstra
Cc: Viresh Kumar, linux-pm, Vincent Guittot, Stephen Boyd,
Nishanth Menon, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Yury Norov, Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
This implements cpu::from_cpu(), which returns a reference to
Device for a CPU. The C struct is created at initialization time for
CPUs and is never freed and so ARef isn't returned from this function.
The new helper will be used by Rust based cpufreq drivers.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
MAINTAINERS | 1 +
rust/bindings/bindings_helper.h | 1 +
rust/kernel/cpu.rs | 31 +++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
4 files changed, 34 insertions(+)
create mode 100644 rust/kernel/cpu.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index 12cde55579a0..475abf72869c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6155,6 +6155,7 @@ F: include/linux/cpuhotplug.h
F: include/linux/smpboot.h
F: kernel/cpu.c
F: kernel/smpboot.*
+F: rust/kernel/cpu.rs
CPU IDLE TIME MANAGEMENT FRAMEWORK
M: "Rafael J. Wysocki" <rafael@kernel.org>
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index f53d6e1a21f2..ac92c67d2c38 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -11,6 +11,7 @@
#include <linux/blk_types.h>
#include <linux/blkdev.h>
#include <linux/clk.h>
+#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/cred.h>
#include <linux/device/faux.h>
diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs
new file mode 100644
index 000000000000..3054165d3818
--- /dev/null
+++ b/rust/kernel/cpu.rs
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Generic CPU definitions.
+//!
+//! C header: [`include/linux/cpu.h`](srctree/include/linux/cpu.h)
+
+use crate::{bindings, device::Device, error::Result, prelude::ENODEV};
+
+/// Creates a new instance of CPU's device.
+///
+/// # Safety
+///
+/// Reference counting is not implemented for the CPU device in the C code. When a CPU is
+/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory
+/// is not freed.
+///
+/// Callers must ensure that the CPU device is not used after it has been unregistered.
+/// This can be achieved, for example, by registering a CPU hotplug notifier and removing
+/// any references to the CPU device within the notifier's callback.
+pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> {
+ // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+ // a `struct device` and is never freed by the C code.
+ let ptr = unsafe { bindings::get_cpu_device(cpu) };
+ if ptr.is_null() {
+ return Err(ENODEV);
+ }
+
+ // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+ // a `struct device` and is never freed by the C code.
+ Ok(unsafe { Device::as_ref(ptr) })
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index f4dcfefe94be..db372f806875 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -44,6 +44,7 @@
pub mod build_assert;
#[cfg(CONFIG_COMMON_CLK)]
pub mod clk;
+pub mod cpu;
pub mod cpumask;
pub mod cred;
pub mod device;
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 09/17] rust: cpu: Add from_cpu()
2025-04-11 10:55 ` [PATCH V9 09/17] rust: cpu: Add from_cpu() Viresh Kumar
@ 2025-04-11 16:18 ` Yury Norov
2025-04-11 18:03 ` Danilo Krummrich
0 siblings, 1 reply; 31+ messages in thread
From: Yury Norov @ 2025-04-11 16:18 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, Thomas Gleixner, Peter Zijlstra, linux-pm,
Vincent Guittot, Stephen Boyd, Nishanth Menon, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Burak Emir, Rasmus Villemoes,
Russell King, linux-clk, Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:08PM +0530, Viresh Kumar wrote:
> This implements cpu::from_cpu(), which returns a reference to
> Device for a CPU. The C struct is created at initialization time for
> CPUs and is never freed and so ARef isn't returned from this function.
>
> The new helper will be used by Rust based cpufreq drivers.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> MAINTAINERS | 1 +
> rust/bindings/bindings_helper.h | 1 +
> rust/kernel/cpu.rs | 31 +++++++++++++++++++++++++++++++
> rust/kernel/lib.rs | 1 +
> 4 files changed, 34 insertions(+)
> create mode 100644 rust/kernel/cpu.rs
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 12cde55579a0..475abf72869c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6155,6 +6155,7 @@ F: include/linux/cpuhotplug.h
> F: include/linux/smpboot.h
> F: kernel/cpu.c
> F: kernel/smpboot.*
> +F: rust/kernel/cpu.rs
>
> CPU IDLE TIME MANAGEMENT FRAMEWORK
> M: "Rafael J. Wysocki" <rafael@kernel.org>
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index f53d6e1a21f2..ac92c67d2c38 100644
> --- a/rust/bindings/bindings_helper.h
> +++ b/rust/bindings/bindings_helper.h
> @@ -11,6 +11,7 @@
> #include <linux/blk_types.h>
> #include <linux/blkdev.h>
> #include <linux/clk.h>
> +#include <linux/cpu.h>
> #include <linux/cpumask.h>
> #include <linux/cred.h>
> #include <linux/device/faux.h>
> diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs
> new file mode 100644
> index 000000000000..3054165d3818
> --- /dev/null
> +++ b/rust/kernel/cpu.rs
> @@ -0,0 +1,31 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Generic CPU definitions.
> +//!
> +//! C header: [`include/linux/cpu.h`](srctree/include/linux/cpu.h)
> +
> +use crate::{bindings, device::Device, error::Result, prelude::ENODEV};
> +
> +/// Creates a new instance of CPU's device.
> +///
> +/// # Safety
> +///
> +/// Reference counting is not implemented for the CPU device in the C code. When a CPU is
> +/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory
> +/// is not freed.
> +///
> +/// Callers must ensure that the CPU device is not used after it has been unregistered.
> +/// This can be achieved, for example, by registering a CPU hotplug notifier and removing
> +/// any references to the CPU device within the notifier's callback.
> +pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> {
> + // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> + // a `struct device` and is never freed by the C code.
> + let ptr = unsafe { bindings::get_cpu_device(cpu) };
> + if ptr.is_null() {
> + return Err(ENODEV);
> + }
> +
> + // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> + // a `struct device` and is never freed by the C code.
If you think that writing the same thing twice would help in SAFETY
department, I'd recommend you to write it for a couple more times.
> + Ok(unsafe { Device::as_ref(ptr) })
> +}
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index f4dcfefe94be..db372f806875 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -44,6 +44,7 @@
> pub mod build_assert;
> #[cfg(CONFIG_COMMON_CLK)]
> pub mod clk;
> +pub mod cpu;
> pub mod cpumask;
> pub mod cred;
> pub mod device;
> --
> 2.31.1.272.g89b43f80a514
^ permalink raw reply [flat|nested] 31+ messages in thread* Re: [PATCH V9 09/17] rust: cpu: Add from_cpu()
2025-04-11 16:18 ` Yury Norov
@ 2025-04-11 18:03 ` Danilo Krummrich
0 siblings, 0 replies; 31+ messages in thread
From: Danilo Krummrich @ 2025-04-11 18:03 UTC (permalink / raw)
To: Yury Norov
Cc: Viresh Kumar, Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Thomas Gleixner, Peter Zijlstra, linux-pm,
Vincent Guittot, Stephen Boyd, Nishanth Menon, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Burak Emir, Rasmus Villemoes,
Russell King, linux-clk, Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 12:18:26PM -0400, Yury Norov wrote:
> On Fri, Apr 11, 2025 at 04:25:08PM +0530, Viresh Kumar wrote:
> > +/// Creates a new instance of CPU's device.
> > +///
> > +/// # Safety
> > +///
> > +/// Reference counting is not implemented for the CPU device in the C code. When a CPU is
> > +/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory
> > +/// is not freed.
> > +///
> > +/// Callers must ensure that the CPU device is not used after it has been unregistered.
> > +/// This can be achieved, for example, by registering a CPU hotplug notifier and removing
> > +/// any references to the CPU device within the notifier's callback.
> > +pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> {
> > + // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> > + // a `struct device` and is never freed by the C code.
> > + let ptr = unsafe { bindings::get_cpu_device(cpu) };
You don't need to justify the return value here, you need to justify why cpu is
a valid value to call get_cpu_device() with.
> > + if ptr.is_null() {
> > + return Err(ENODEV);
> > + }
> > +
> > + // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> > + // a `struct device` and is never freed by the C code.
Here, the comment is good.
> If you think that writing the same thing twice would help in SAFETY
> department, I'd recommend you to write it for a couple more times.
Fixing the above, should also fix the duplication. :)
> > + Ok(unsafe { Device::as_ref(ptr) })
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 10/17] rust: opp: Add initial abstractions for OPP framework
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (8 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 09/17] rust: cpu: Add from_cpu() Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 11/17] rust: opp: Add abstractions for the OPP table Viresh Kumar
` (6 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, Viresh Kumar, Nishanth Menon, Stephen Boyd
Cc: Viresh Kumar, linux-pm, Vincent Guittot, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Yury Norov, Burak Emir,
Rasmus Villemoes, Russell King, linux-clk, Michael Turquette,
linux-kernel
Introduce initial Rust abstractions for the Operating Performance Points
(OPP) framework. This includes bindings for `struct dev_pm_opp` and
`struct dev_pm_opp_data`, laying the groundwork for further OPP
integration.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
MAINTAINERS | 1 +
rust/bindings/bindings_helper.h | 1 +
rust/kernel/lib.rs | 2 +
rust/kernel/opp.rs | 300 ++++++++++++++++++++++++++++++++
4 files changed, 304 insertions(+)
create mode 100644 rust/kernel/opp.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index 475abf72869c..931e418f89ed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18165,6 +18165,7 @@ F: Documentation/devicetree/bindings/opp/
F: Documentation/power/opp.rst
F: drivers/opp/
F: include/linux/pm_opp.h
+F: rust/kernel/opp.rs
OPL4 DRIVER
M: Clemens Ladisch <clemens@ladisch.de>
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ac92c67d2c38..529f22891e0b 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -30,6 +30,7 @@
#include <linux/phy.h>
#include <linux/pid_namespace.h>
#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
#include <linux/poll.h>
#include <linux/property.h>
#include <linux/refcount.h>
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index db372f806875..11d333c8c673 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -68,6 +68,8 @@
#[cfg(CONFIG_NET)]
pub mod net;
pub mod of;
+#[cfg(CONFIG_PM_OPP)]
+pub mod opp;
pub mod page;
#[cfg(CONFIG_PCI)]
pub mod pci;
diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
new file mode 100644
index 000000000000..e4780b41664f
--- /dev/null
+++ b/rust/kernel/opp.rs
@@ -0,0 +1,300 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Operating performance points.
+//!
+//! This module provides rust abstractions for interacting with the OPP subsystem.
+//!
+//! C header: [`include/linux/pm_opp.h`](srctree/include/linux/pm_opp.h)
+//!
+//! Reference: <https://docs.kernel.org/power/opp.html>
+
+use crate::{
+ bindings,
+ clk::Hertz,
+ device::Device,
+ error::{code::*, to_result, Result},
+ ffi::c_ulong,
+ types::{ARef, AlwaysRefCounted, Opaque},
+};
+
+use core::ptr;
+
+/// The voltage unit.
+///
+/// Represents voltage in microvolts, wrapping a [`c_ulong`] value.
+///
+/// ## Examples
+///
+/// ```
+/// use kernel::opp::MicroVolt;
+///
+/// let raw = 90500;
+/// let volt = MicroVolt(raw);
+///
+/// assert_eq!(usize::from(volt), raw);
+/// assert_eq!(volt, MicroVolt(raw));
+/// ```
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct MicroVolt(pub c_ulong);
+
+impl From<MicroVolt> for c_ulong {
+ #[inline]
+ fn from(volt: MicroVolt) -> Self {
+ volt.0
+ }
+}
+
+/// The power unit.
+///
+/// Represents power in microwatts, wrapping a [`c_ulong`] value.
+///
+/// ## Examples
+///
+/// ```
+/// use kernel::opp::MicroWatt;
+///
+/// let raw = 1000000;
+/// let power = MicroWatt(raw);
+///
+/// assert_eq!(usize::from(power), raw);
+/// assert_eq!(power, MicroWatt(raw));
+/// ```
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct MicroWatt(pub c_ulong);
+
+impl From<MicroWatt> for c_ulong {
+ #[inline]
+ fn from(power: MicroWatt) -> Self {
+ power.0
+ }
+}
+
+/// Handle for a dynamically created [`OPP`].
+///
+/// The associated [`OPP`] is automatically removed when the [`Token`] is dropped.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create an [`OPP`] dynamically.
+///
+/// ```
+/// use kernel::clk::Hertz;
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+/// use kernel::opp::{Data, MicroVolt, Token};
+/// use kernel::types::ARef;
+///
+/// fn create_opp(dev: &ARef<Device>, freq: Hertz, volt: MicroVolt, level: u32) -> Result<Token> {
+/// let data = Data::new(freq, volt, level, false);
+///
+/// // OPP is removed once token goes out of scope.
+/// data.add_opp(dev)
+/// }
+/// ```
+pub struct Token {
+ dev: ARef<Device>,
+ freq: Hertz,
+}
+
+impl Token {
+ /// Dynamically adds an [`OPP`] and returns a [`Token`] that removes it on drop.
+ fn new(dev: &ARef<Device>, mut data: Data) -> Result<Self> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_add_dynamic(dev.as_raw(), &mut data.0) })?;
+ Ok(Self {
+ dev: dev.clone(),
+ freq: data.freq(),
+ })
+ }
+}
+
+impl Drop for Token {
+ fn drop(&mut self) {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ unsafe { bindings::dev_pm_opp_remove(self.dev.as_raw(), self.freq.into()) };
+ }
+}
+
+/// OPP data.
+///
+/// Rust abstraction for the C `struct dev_pm_opp_data`, used to define operating performance
+/// points (OPPs) dynamically.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create an [`OPP`] with [`Data`].
+///
+/// ```
+/// use kernel::clk::Hertz;
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+/// use kernel::opp::{Data, MicroVolt, Token};
+/// use kernel::types::ARef;
+///
+/// fn create_opp(dev: &ARef<Device>, freq: Hertz, volt: MicroVolt, level: u32) -> Result<Token> {
+/// let data = Data::new(freq, volt, level, false);
+///
+/// // OPP is removed once token goes out of scope.
+/// data.add_opp(dev)
+/// }
+/// ```
+#[repr(transparent)]
+pub struct Data(bindings::dev_pm_opp_data);
+
+impl Data {
+ /// Creates a new instance of [`Data`].
+ ///
+ /// This can be used to define a dynamic OPP to be added to a device.
+ pub fn new(freq: Hertz, volt: MicroVolt, level: u32, turbo: bool) -> Self {
+ Self(bindings::dev_pm_opp_data {
+ turbo,
+ freq: freq.into(),
+ u_volt: volt.into(),
+ level,
+ })
+ }
+
+ /// Adds an [`OPP`] dynamically.
+ ///
+ /// Returns a [`Token`] that ensures the OPP is automatically removed
+ /// when it goes out of scope.
+ #[inline]
+ pub fn add_opp(self, dev: &ARef<Device>) -> Result<Token> {
+ Token::new(dev, self)
+ }
+
+ // Returns the frequency associated with this OPP data.
+ #[inline]
+ fn freq(&self) -> Hertz {
+ Hertz(self.0.freq)
+ }
+}
+
+/// A reference-counted Operating performance point (OPP).
+///
+/// Rust abstraction for the C `struct dev_pm_opp`.
+///
+/// # Invariants
+///
+/// The pointer stored in `Self` is non-null and valid for the lifetime of the [`OPP`].
+///
+/// Instances of this type are reference-counted. The reference count is incremented by the
+/// `dev_pm_opp_get` function and decremented by `dev_pm_opp_put`. The Rust type `ARef<OPP>`
+/// represents a pointer that owns a reference count on the [`OPP`].
+///
+/// A reference to the [`OPP`], &[`OPP`], isn't refcounted by the Rust code.
+#[repr(transparent)]
+pub struct OPP(Opaque<bindings::dev_pm_opp>);
+
+// SAFETY: It is okay to send the ownership of [`OPP`] across thread boundaries.
+unsafe impl Send for OPP {}
+
+// SAFETY: It is okay to access [`OPP`] through shared references from other threads because we're
+// either accessing properties that don't change or that are properly synchronised by C code.
+unsafe impl Sync for OPP {}
+
+// SAFETY: The type invariants guarantee that [`OPP`] is always refcounted.
+unsafe impl AlwaysRefCounted for OPP {
+ fn inc_ref(&self) {
+ // SAFETY: The existence of a shared reference means that the refcount is nonzero.
+ unsafe { bindings::dev_pm_opp_get(self.0.get()) };
+ }
+
+ unsafe fn dec_ref(obj: ptr::NonNull<Self>) {
+ // SAFETY: The safety requirements guarantee that the refcount is nonzero.
+ unsafe { bindings::dev_pm_opp_put(obj.cast().as_ptr()) }
+ }
+}
+
+impl OPP {
+ /// Creates an owned reference to a [`OPP`] from a valid pointer.
+ ///
+ /// The refcount is incremented by the C code and will be decremented by `dec_ref` when the
+ /// [`ARef`] object is dropped.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid and the refcount of the [`OPP`] is incremented.
+ /// The caller must also ensure that it doesn't explicitly drop the refcount of the [`OPP`], as
+ /// the returned [`ARef`] object takes over the refcount increment on the underlying object and
+ /// the same will be dropped along with it.
+ pub unsafe fn from_raw_opp_owned(ptr: *mut bindings::dev_pm_opp) -> Result<ARef<Self>> {
+ let ptr = ptr::NonNull::new(ptr).ok_or(ENODEV)?;
+
+ // SAFETY: The safety requirements guarantee the validity of the pointer.
+ //
+ // INVARIANT: The reference-count is decremented when [`OPP`] goes out of scope.
+ Ok(unsafe { ARef::from_raw(ptr.cast()) })
+ }
+
+ /// Creates a reference to a [`OPP`] from a valid pointer.
+ ///
+ /// The refcount is not updated by the Rust API unless the returned reference is converted to
+ /// an [`ARef`] object.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid and remains valid for the duration of `'a`.
+ #[inline]
+ pub unsafe fn from_raw_opp<'a>(ptr: *mut bindings::dev_pm_opp) -> Result<&'a Self> {
+ // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the
+ // duration of 'a. The cast is okay because [`OPP`] is `repr(transparent)`.
+ Ok(unsafe { &*ptr.cast() })
+ }
+
+ #[inline]
+ fn as_raw(&self) -> *mut bindings::dev_pm_opp {
+ self.0.get()
+ }
+
+ /// Returns the frequency of an [`OPP`].
+ pub fn freq(&self, index: Option<u32>) -> Hertz {
+ let index = index.unwrap_or(0);
+
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ Hertz(unsafe { bindings::dev_pm_opp_get_freq_indexed(self.as_raw(), index) })
+ }
+
+ /// Returns the voltage of an [`OPP`].
+ #[inline]
+ pub fn voltage(&self) -> MicroVolt {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ MicroVolt(unsafe { bindings::dev_pm_opp_get_voltage(self.as_raw()) })
+ }
+
+ /// Returns the level of an [`OPP`].
+ #[inline]
+ pub fn level(&self) -> u32 {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ unsafe { bindings::dev_pm_opp_get_level(self.as_raw()) }
+ }
+
+ /// Returns the power of an [`OPP`].
+ #[inline]
+ pub fn power(&self) -> MicroWatt {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ MicroWatt(unsafe { bindings::dev_pm_opp_get_power(self.as_raw()) })
+ }
+
+ /// Returns the required pstate of an [`OPP`].
+ #[inline]
+ pub fn required_pstate(&self, index: u32) -> u32 {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ unsafe { bindings::dev_pm_opp_get_required_pstate(self.as_raw(), index) }
+ }
+
+ /// Returns true if the [`OPP`] is turbo.
+ #[inline]
+ pub fn is_turbo(&self) -> bool {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+ // use it.
+ unsafe { bindings::dev_pm_opp_is_turbo(self.as_raw()) }
+ }
+}
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 11/17] rust: opp: Add abstractions for the OPP table
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (9 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 10/17] rust: opp: Add initial abstractions for OPP framework Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 16:29 ` Yury Norov
2025-04-11 10:55 ` [PATCH V9 12/17] rust: opp: Add abstractions for the configuration options Viresh Kumar
` (5 subsequent siblings)
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Nishanth Menon, Stephen Boyd, Miguel Ojeda, Alex Gaynor,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Yury Norov, Burak Emir,
Rasmus Villemoes, Russell King, linux-clk, Michael Turquette,
linux-kernel
Introduce Rust abstractions for `struct opp_table`, enabling access to
OPP tables from Rust.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/opp.rs | 495 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 494 insertions(+), 1 deletion(-)
diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index e4780b41664f..e074009e4b7a 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -11,8 +11,9 @@
use crate::{
bindings,
clk::Hertz,
+ cpumask::{Cpumask, CpumaskVar},
device::Device,
- error::{code::*, to_result, Result},
+ error::{code::*, from_err_ptr, to_result, Error, Result},
ffi::c_ulong,
types::{ARef, AlwaysRefCounted, Opaque},
};
@@ -172,6 +173,477 @@ fn freq(&self) -> Hertz {
}
}
+/// [`OPP`] search options.
+///
+/// ## Examples
+///
+/// Defines how to search for an [`OPP`] in a [`Table`] relative to a frequency.
+///
+/// ```
+/// use kernel::clk::Hertz;
+/// use kernel::error::Result;
+/// use kernel::opp::{OPP, SearchType, Table};
+/// use kernel::types::ARef;
+///
+/// fn find_opp(table: &Table, freq: Hertz) -> Result<ARef<OPP>> {
+/// let opp = table.opp_from_freq(freq, Some(true), None, SearchType::Exact)?;
+///
+/// pr_info!("OPP frequency is: {:?}\n", opp.freq(None));
+/// pr_info!("OPP voltage is: {:?}\n", opp.voltage());
+/// pr_info!("OPP level is: {}\n", opp.level());
+/// pr_info!("OPP power is: {:?}\n", opp.power());
+///
+/// Ok(opp)
+/// }
+/// ```
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum SearchType {
+ /// Match the exact frequency.
+ Exact,
+ /// Find the highest frequency less than or equal to the given value.
+ Floor,
+ /// Find the lowest frequency greater than or equal to the given value.
+ Ceil,
+}
+
+/// A reference-counted OPP table.
+///
+/// Rust abstraction for the C `struct opp_table`.
+///
+/// # Invariants
+///
+/// The pointer stored in `Self` is non-null and valid for the lifetime of the [`Table`].
+///
+/// Instances of this type are reference-counted.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to get OPP [`Table`] for a [`Cpumask`] and set its
+/// frequency.
+///
+/// ```
+/// use kernel::clk::Hertz;
+/// use kernel::cpumask::Cpumask;
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+/// use kernel::opp::Table;
+/// use kernel::types::ARef;
+///
+/// fn get_table(dev: &ARef<Device>, mask: &mut Cpumask, freq: Hertz) -> Result<Table> {
+/// let mut opp_table = Table::from_of_cpumask(dev, mask)?;
+///
+/// if opp_table.opp_count()? == 0 {
+/// return Err(EINVAL);
+/// }
+///
+/// pr_info!("Max transition latency is: {} ns\n", opp_table.max_transition_latency_ns());
+/// pr_info!("Suspend frequency is: {:?}\n", opp_table.suspend_freq());
+///
+/// opp_table.set_rate(freq)?;
+/// Ok(opp_table)
+/// }
+/// ```
+pub struct Table {
+ ptr: *mut bindings::opp_table,
+ dev: ARef<Device>,
+ em: bool,
+ of: bool,
+ cpumask_box: Option<CpumaskVar>,
+}
+
+// SAFETY: It is okay to send ownership of [`Table`] across thread boundaries.
+unsafe impl Send for Table {}
+
+// SAFETY: It is okay to access [`Table`] through shared references from other threads because
+// we're either accessing properties that don't change or that are properly synchronised by C code.
+unsafe impl Sync for Table {}
+
+impl Table {
+ /// Creates a new reference-counted [`Table`] from a raw pointer.
+ ///
+ /// # Safety
+ ///
+ /// Callers must ensure that `ptr` is valid and non-null.
+ unsafe fn from_raw_table(ptr: *mut bindings::opp_table, dev: &ARef<Device>) -> Self {
+ // SAFETY: By the safety requirements, ptr is valid and its refcount will be incremented.
+ //
+ // INVARIANT: The reference-count is decremented when [`Table`] goes out of scope.
+ unsafe { bindings::dev_pm_opp_get_opp_table_ref(ptr) };
+
+ Self {
+ ptr,
+ dev: dev.clone(),
+ em: false,
+ of: false,
+ cpumask_box: None,
+ }
+ }
+
+ /// Creates a new reference-counted [`Table`] instance for a [`Device`].
+ pub fn from_dev(dev: &Device) -> Result<Self> {
+ // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety
+ // requirements.
+ //
+ // INVARIANT: The reference-count is incremented by the C code and is decremented when
+ // [`Table`] goes out of scope.
+ let ptr = from_err_ptr(unsafe { bindings::dev_pm_opp_get_opp_table(dev.as_raw()) })?;
+
+ Ok(Self {
+ ptr,
+ dev: dev.into(),
+ em: false,
+ of: false,
+ cpumask_box: None,
+ })
+ }
+
+ /// Creates a new reference-counted [`Table`] instance for a [`Device`] based on device tree
+ /// entries.
+ #[cfg(CONFIG_OF)]
+ pub fn from_of(dev: &ARef<Device>, index: i32) -> Result<Self> {
+ // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety
+ // requirements.
+ //
+ // INVARIANT: The reference-count is incremented by the C code and is decremented when
+ // [`Table`] goes out of scope.
+ to_result(unsafe { bindings::dev_pm_opp_of_add_table_indexed(dev.as_raw(), index) })?;
+
+ // Get the newly created [`Table`].
+ let mut table = Self::from_dev(dev)?;
+ table.of = true;
+
+ Ok(table)
+ }
+
+ // Remove device tree based [`Table`].
+ #[cfg(CONFIG_OF)]
+ #[inline]
+ fn remove_of(&self) {
+ // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety
+ // requirements. We took the reference from [`from_of`] earlier, it is safe to drop the
+ // same now.
+ unsafe { bindings::dev_pm_opp_of_remove_table(self.dev.as_raw()) };
+ }
+
+ /// Creates a new reference-counted [`Table`] instance for a [`Cpumask`] based on device tree
+ /// entries.
+ #[cfg(CONFIG_OF)]
+ pub fn from_of_cpumask(dev: &Device, cpumask: &mut Cpumask) -> Result<Self> {
+ // SAFETY: The cpumask is valid and the returned pointer will be owned by the [`Table`]
+ // instance.
+ //
+ // INVARIANT: The reference-count is incremented by the C code and is decremented when
+ // [`Table`] goes out of scope.
+ to_result(unsafe { bindings::dev_pm_opp_of_cpumask_add_table(cpumask.as_raw()) })?;
+
+ // Fetch the newly created table.
+ let mut table = Self::from_dev(dev)?;
+ table.cpumask_box = Some(CpumaskVar::try_clone(cpumask)?);
+
+ Ok(table)
+ }
+
+ // Remove device tree based [`Table`] for a [`Cpumask`].
+ #[cfg(CONFIG_OF)]
+ #[inline]
+ fn remove_of_cpumask(&self, cpumask: &Cpumask) {
+ // SAFETY: The cpumask is valid and we took the reference from [`from_of_cpumask`] earlier,
+ // it is safe to drop the same now.
+ unsafe { bindings::dev_pm_opp_of_cpumask_remove_table(cpumask.as_raw()) };
+ }
+
+ /// Returns the number of [`OPP`]s in the [`Table`].
+ pub fn opp_count(&self) -> Result<u32> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ let ret = unsafe { bindings::dev_pm_opp_get_opp_count(self.dev.as_raw()) };
+ if ret < 0 {
+ Err(Error::from_errno(ret))
+ } else {
+ Ok(ret as u32)
+ }
+ }
+
+ /// Returns max clock latency (in nanoseconds) of the [`OPP`]s in the [`Table`].
+ #[inline]
+ pub fn max_clock_latency_ns(&self) -> usize {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ unsafe { bindings::dev_pm_opp_get_max_clock_latency(self.dev.as_raw()) }
+ }
+
+ /// Returns max volt latency (in nanoseconds) of the [`OPP`]s in the [`Table`].
+ #[inline]
+ pub fn max_volt_latency_ns(&self) -> usize {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ unsafe { bindings::dev_pm_opp_get_max_volt_latency(self.dev.as_raw()) }
+ }
+
+ /// Returns max transition latency (in nanoseconds) of the [`OPP`]s in the [`Table`].
+ #[inline]
+ pub fn max_transition_latency_ns(&self) -> usize {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ unsafe { bindings::dev_pm_opp_get_max_transition_latency(self.dev.as_raw()) }
+ }
+
+ /// Returns the suspend [`OPP`]'s frequency.
+ #[inline]
+ pub fn suspend_freq(&self) -> Hertz {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ Hertz(unsafe { bindings::dev_pm_opp_get_suspend_opp_freq(self.dev.as_raw()) })
+ }
+
+ /// Synchronizes regulators used by the [`Table`].
+ #[inline]
+ pub fn sync_regulators(&self) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_sync_regulators(self.dev.as_raw()) })
+ }
+
+ /// Gets sharing CPUs.
+ #[inline]
+ pub fn sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_get_sharing_cpus(dev.as_raw(), cpumask.as_raw()) })
+ }
+
+ /// Sets sharing CPUs.
+ pub fn set_sharing_cpus(&mut self, cpumask: &mut Cpumask) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe {
+ bindings::dev_pm_opp_set_sharing_cpus(self.dev.as_raw(), cpumask.as_raw())
+ })?;
+
+ if let Some(mask) = self.cpumask_box.as_mut() {
+ // Update the cpumask as this will be used while removing the table.
+ cpumask.copy(mask);
+ }
+
+ Ok(())
+ }
+
+ /// Gets sharing CPUs from device tree.
+ #[cfg(CONFIG_OF)]
+ #[inline]
+ pub fn of_sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe {
+ bindings::dev_pm_opp_of_get_sharing_cpus(dev.as_raw(), cpumask.as_raw())
+ })
+ }
+
+ /// Updates the voltage value for an [`OPP`].
+ #[inline]
+ pub fn adjust_voltage(
+ &self,
+ freq: Hertz,
+ volt: MicroVolt,
+ volt_min: MicroVolt,
+ volt_max: MicroVolt,
+ ) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe {
+ bindings::dev_pm_opp_adjust_voltage(
+ self.dev.as_raw(),
+ freq.into(),
+ volt.into(),
+ volt_min.into(),
+ volt_max.into(),
+ )
+ })
+ }
+
+ /// Configures device with [`OPP`] matching the frequency value.
+ #[inline]
+ pub fn set_rate(&self, freq: Hertz) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_set_rate(self.dev.as_raw(), freq.into()) })
+ }
+
+ /// Configures device with [`OPP`].
+ #[inline]
+ pub fn set_opp(&self, opp: &OPP) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_set_opp(self.dev.as_raw(), opp.as_raw()) })
+ }
+
+ /// Finds [`OPP`] based on frequency.
+ pub fn opp_from_freq(
+ &self,
+ freq: Hertz,
+ available: Option<bool>,
+ index: Option<u32>,
+ stype: SearchType,
+ ) -> Result<ARef<OPP>> {
+ let raw_dev = self.dev.as_raw();
+ let index = index.unwrap_or(0);
+
+ let ptr = from_err_ptr(match stype {
+ SearchType::Exact => {
+ if let Some(available) = available {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and
+ // its safety requirements. The returned pointer will be owned by the new
+ // [`OPP`] instance.
+ unsafe {
+ bindings::dev_pm_opp_find_freq_exact_indexed(
+ raw_dev,
+ freq.into(),
+ index,
+ available,
+ )
+ }
+ } else {
+ return Err(EINVAL);
+ }
+ }
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Ceil => unsafe {
+ bindings::dev_pm_opp_find_freq_ceil_indexed(
+ raw_dev,
+ &mut freq.into() as *mut usize,
+ index,
+ )
+ },
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Floor => unsafe {
+ bindings::dev_pm_opp_find_freq_floor_indexed(
+ raw_dev,
+ &mut freq.into() as *mut usize,
+ index,
+ )
+ },
+ })?;
+
+ // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp_owned(ptr) }
+ }
+
+ /// Finds [`OPP`] based on level.
+ pub fn opp_from_level(&self, mut level: u32, stype: SearchType) -> Result<ARef<OPP>> {
+ let raw_dev = self.dev.as_raw();
+
+ let ptr = from_err_ptr(match stype {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Exact => unsafe { bindings::dev_pm_opp_find_level_exact(raw_dev, level) },
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Ceil => unsafe {
+ bindings::dev_pm_opp_find_level_ceil(raw_dev, &mut level as *mut u32)
+ },
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Floor => unsafe {
+ bindings::dev_pm_opp_find_level_floor(raw_dev, &mut level as *mut u32)
+ },
+ })?;
+
+ // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp_owned(ptr) }
+ }
+
+ /// Finds [`OPP`] based on bandwidth.
+ pub fn opp_from_bw(&self, mut bw: u32, index: i32, stype: SearchType) -> Result<ARef<OPP>> {
+ let raw_dev = self.dev.as_raw();
+
+ let ptr = from_err_ptr(match stype {
+ // The OPP core doesn't support this yet.
+ SearchType::Exact => return Err(EINVAL),
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Ceil => unsafe {
+ bindings::dev_pm_opp_find_bw_ceil(raw_dev, &mut bw as *mut u32, index)
+ },
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The returned pointer will be owned by the new [`OPP`] instance.
+ SearchType::Floor => unsafe {
+ bindings::dev_pm_opp_find_bw_floor(raw_dev, &mut bw as *mut u32, index)
+ },
+ })?;
+
+ // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp_owned(ptr) }
+ }
+
+ /// Enables the [`OPP`].
+ #[inline]
+ pub fn enable_opp(&self, freq: Hertz) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_enable(self.dev.as_raw(), freq.into()) })
+ }
+
+ /// Disables the [`OPP`].
+ #[inline]
+ pub fn disable_opp(&self, freq: Hertz) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe { bindings::dev_pm_opp_disable(self.dev.as_raw(), freq.into()) })
+ }
+
+ /// Registers with Energy model.
+ #[cfg(CONFIG_OF)]
+ pub fn of_register_em(&mut self, cpumask: &mut Cpumask) -> Result<()> {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe {
+ bindings::dev_pm_opp_of_register_em(self.dev.as_raw(), cpumask.as_raw())
+ })?;
+
+ self.em = true;
+ Ok(())
+ }
+
+ // Unregisters with Energy model.
+ #[cfg(all(CONFIG_OF, CONFIG_ENERGY_MODEL))]
+ #[inline]
+ fn of_unregister_em(&self) {
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. We registered with the EM framework earlier, it is safe to unregister now.
+ unsafe { bindings::em_dev_unregister_perf_domain(self.dev.as_raw()) };
+ }
+}
+
+impl Drop for Table {
+ fn drop(&mut self) {
+ // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe
+ // to relinquish it now.
+ unsafe { bindings::dev_pm_opp_put_opp_table(self.ptr) };
+
+ #[cfg(CONFIG_OF)]
+ {
+ #[cfg(CONFIG_ENERGY_MODEL)]
+ if self.em {
+ self.of_unregister_em();
+ }
+
+ if self.of {
+ self.remove_of();
+ } else if let Some(cpumask) = self.cpumask_box.take() {
+ self.remove_of_cpumask(&cpumask);
+ }
+ }
+ }
+}
+
/// A reference-counted Operating performance point (OPP).
///
/// Rust abstraction for the C `struct dev_pm_opp`.
@@ -185,6 +657,27 @@ fn freq(&self) -> Hertz {
/// represents a pointer that owns a reference count on the [`OPP`].
///
/// A reference to the [`OPP`], &[`OPP`], isn't refcounted by the Rust code.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to get [`OPP`] corresponding to a frequency value and
+/// configure the device with it.
+///
+/// ```
+/// use kernel::clk::Hertz;
+/// use kernel::error::Result;
+/// use kernel::opp::{SearchType, Table};
+///
+/// fn configure_opp(table: &Table, freq: Hertz) -> Result {
+/// let opp = table.opp_from_freq(freq, Some(true), None, SearchType::Exact)?;
+///
+/// if opp.freq(None) != freq {
+/// return Err(EINVAL);
+/// }
+///
+/// table.set_opp(&opp)
+/// }
+/// ```
#[repr(transparent)]
pub struct OPP(Opaque<bindings::dev_pm_opp>);
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 11/17] rust: opp: Add abstractions for the OPP table
2025-04-11 10:55 ` [PATCH V9 11/17] rust: opp: Add abstractions for the OPP table Viresh Kumar
@ 2025-04-11 16:29 ` Yury Norov
0 siblings, 0 replies; 31+ messages in thread
From: Yury Norov @ 2025-04-11 16:29 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Nishanth Menon, Stephen Boyd, Miguel Ojeda, Alex Gaynor,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Danilo Krummrich,
linux-pm, Vincent Guittot, rust-for-linux, Manos Pitsidianakis,
Erik Schilling, Alex Bennée, Joakim Bech, Rob Herring,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:10PM +0530, Viresh Kumar wrote:
> Introduce Rust abstractions for `struct opp_table`, enabling access to
> OPP tables from Rust.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> rust/kernel/opp.rs | 495 ++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 494 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
> index e4780b41664f..e074009e4b7a 100644
> --- a/rust/kernel/opp.rs
> +++ b/rust/kernel/opp.rs
> @@ -11,8 +11,9 @@
> use crate::{
> bindings,
> clk::Hertz,
> + cpumask::{Cpumask, CpumaskVar},
> device::Device,
> - error::{code::*, to_result, Result},
> + error::{code::*, from_err_ptr, to_result, Error, Result},
> ffi::c_ulong,
> types::{ARef, AlwaysRefCounted, Opaque},
> };
> @@ -172,6 +173,477 @@ fn freq(&self) -> Hertz {
> }
> }
>
> +/// [`OPP`] search options.
> +///
> +/// ## Examples
> +///
> +/// Defines how to search for an [`OPP`] in a [`Table`] relative to a frequency.
> +///
> +/// ```
> +/// use kernel::clk::Hertz;
> +/// use kernel::error::Result;
> +/// use kernel::opp::{OPP, SearchType, Table};
> +/// use kernel::types::ARef;
> +///
> +/// fn find_opp(table: &Table, freq: Hertz) -> Result<ARef<OPP>> {
> +/// let opp = table.opp_from_freq(freq, Some(true), None, SearchType::Exact)?;
> +///
> +/// pr_info!("OPP frequency is: {:?}\n", opp.freq(None));
> +/// pr_info!("OPP voltage is: {:?}\n", opp.voltage());
> +/// pr_info!("OPP level is: {}\n", opp.level());
> +/// pr_info!("OPP power is: {:?}\n", opp.power());
> +///
> +/// Ok(opp)
> +/// }
> +/// ```
> +#[derive(Copy, Clone, Debug, Eq, PartialEq)]
> +pub enum SearchType {
> + /// Match the exact frequency.
> + Exact,
> + /// Find the highest frequency less than or equal to the given value.
> + Floor,
> + /// Find the lowest frequency greater than or equal to the given value.
> + Ceil,
> +}
> +
> +/// A reference-counted OPP table.
> +///
> +/// Rust abstraction for the C `struct opp_table`.
> +///
> +/// # Invariants
> +///
> +/// The pointer stored in `Self` is non-null and valid for the lifetime of the [`Table`].
> +///
> +/// Instances of this type are reference-counted.
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to get OPP [`Table`] for a [`Cpumask`] and set its
> +/// frequency.
> +///
> +/// ```
> +/// use kernel::clk::Hertz;
> +/// use kernel::cpumask::Cpumask;
> +/// use kernel::device::Device;
> +/// use kernel::error::Result;
> +/// use kernel::opp::Table;
> +/// use kernel::types::ARef;
> +///
> +/// fn get_table(dev: &ARef<Device>, mask: &mut Cpumask, freq: Hertz) -> Result<Table> {
> +/// let mut opp_table = Table::from_of_cpumask(dev, mask)?;
> +///
> +/// if opp_table.opp_count()? == 0 {
> +/// return Err(EINVAL);
> +/// }
> +///
> +/// pr_info!("Max transition latency is: {} ns\n", opp_table.max_transition_latency_ns());
> +/// pr_info!("Suspend frequency is: {:?}\n", opp_table.suspend_freq());
> +///
> +/// opp_table.set_rate(freq)?;
> +/// Ok(opp_table)
> +/// }
> +/// ```
> +pub struct Table {
> + ptr: *mut bindings::opp_table,
> + dev: ARef<Device>,
> + em: bool,
> + of: bool,
> + cpumask_box: Option<CpumaskVar>,
The other fields have short names. Maybe just 'cpus' instead of
cpumask_box? If you want to put the type of variable into the name, it
should be a cpumask_var.
> +}
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 12/17] rust: opp: Add abstractions for the configuration options
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (10 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 11/17] rust: opp: Add abstractions for the OPP table Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 13/17] rust: cpufreq: Add initial abstractions for cpufreq framework Viresh Kumar
` (4 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Nishanth Menon, Stephen Boyd, Miguel Ojeda, Alex Gaynor,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Yury Norov, Burak Emir,
Rasmus Villemoes, Russell King, linux-clk, Michael Turquette,
linux-kernel
Introduce Rust abstractions for the OPP core configuration options,
enabling safe access to various configurable aspects of the OPP
framework.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/opp.rs | 295 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 293 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index e074009e4b7a..7bf612fa0cc5 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -13,12 +13,29 @@
clk::Hertz,
cpumask::{Cpumask, CpumaskVar},
device::Device,
- error::{code::*, from_err_ptr, to_result, Error, Result},
+ error::{code::*, from_err_ptr, from_result, to_result, Error, Result, VTABLE_DEFAULT_ERROR},
ffi::c_ulong,
+ prelude::*,
+ str::CString,
types::{ARef, AlwaysRefCounted, Opaque},
};
-use core::ptr;
+use core::{marker::PhantomData, ptr};
+
+use macros::vtable;
+
+// Creates a null-terminated slice of pointers to [`Cstring`]s.
+fn to_c_str_array(names: &[CString]) -> Result<KVec<*const u8>> {
+ // Allocated a null-terminated vector of pointers.
+ let mut list = KVec::with_capacity(names.len() + 1, GFP_KERNEL)?;
+
+ for name in names.iter() {
+ list.push(name.as_ptr() as _, GFP_KERNEL)?;
+ }
+
+ list.push(ptr::null(), GFP_KERNEL)?;
+ Ok(list)
+}
/// The voltage unit.
///
@@ -206,6 +223,280 @@ pub enum SearchType {
Ceil,
}
+/// OPP configuration callbacks.
+///
+/// Implement this trait to customize OPP clock and regulator setup for your device.
+#[vtable]
+pub trait ConfigOps {
+ /// This is typically used to scale clocks when transitioning between OPPs.
+ #[inline]
+ fn config_clks(_dev: &Device, _table: &Table, _opp: &OPP, _scaling_down: bool) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// This provides access to the old and new OPPs, allowing for safe regulator adjustments.
+ #[inline]
+ fn config_regulators(
+ _dev: &Device,
+ _opp_old: &OPP,
+ _opp_new: &OPP,
+ _data: *mut *mut bindings::regulator,
+ _count: u32,
+ ) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+}
+
+/// OPP configuration token.
+///
+/// Returned by the OPP core when configuration is applied to a [`Device`]. The associated
+/// configuration is automatically cleared when the token is dropped.
+pub struct ConfigToken(i32);
+
+impl Drop for ConfigToken {
+ fn drop(&mut self) {
+ // SAFETY: This is the same token value returned by the C code via `dev_pm_opp_set_config`.
+ unsafe { bindings::dev_pm_opp_clear_config(self.0) };
+ }
+}
+
+/// OPP configurations.
+///
+/// Rust abstraction for the C `struct dev_pm_opp_config`.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to set OPP property-name configuration for a [`Device`].
+///
+/// ```
+/// use kernel::device::Device;
+/// use kernel::error::Result;
+/// use kernel::opp::{Config, ConfigOps, ConfigToken};
+/// use kernel::str::CString;
+/// use kernel::types::ARef;
+/// use kernel::macros::vtable;
+///
+/// #[derive(Default)]
+/// struct Driver;
+///
+/// #[vtable]
+/// impl ConfigOps for Driver {}
+///
+/// fn configure(dev: &ARef<Device>) -> Result<ConfigToken> {
+/// let name = CString::try_from_fmt(fmt!("{}", "slow"))?;
+///
+/// // The OPP configuration is cleared once the [`ConfigToken`] goes out of scope.
+/// Config::<Driver>::new()
+/// .set_prop_name(name)?
+/// .set(dev)
+/// }
+/// ```
+#[derive(Default)]
+pub struct Config<T: ConfigOps>
+where
+ T: Default,
+{
+ clk_names: Option<KVec<CString>>,
+ prop_name: Option<CString>,
+ regulator_names: Option<KVec<CString>>,
+ supported_hw: Option<KVec<u32>>,
+
+ // Tuple containing (required device, index)
+ required_dev: Option<(ARef<Device>, u32)>,
+ _data: PhantomData<T>,
+}
+
+impl<T: ConfigOps + Default> Config<T> {
+ /// Creates a new instance of [`Config`].
+ #[inline]
+ pub fn new() -> Self {
+ Self::default()
+ }
+
+ /// Initializes clock names.
+ pub fn set_clk_names(mut self, names: KVec<CString>) -> Result<Self> {
+ if self.clk_names.is_some() {
+ return Err(EBUSY);
+ }
+
+ if names.is_empty() {
+ return Err(EINVAL);
+ }
+
+ self.clk_names = Some(names);
+ Ok(self)
+ }
+
+ /// Initializes property name.
+ pub fn set_prop_name(mut self, name: CString) -> Result<Self> {
+ if self.prop_name.is_some() {
+ return Err(EBUSY);
+ }
+
+ self.prop_name = Some(name);
+ Ok(self)
+ }
+
+ /// Initializes regulator names.
+ pub fn set_regulator_names(mut self, names: KVec<CString>) -> Result<Self> {
+ if self.regulator_names.is_some() {
+ return Err(EBUSY);
+ }
+
+ if names.is_empty() {
+ return Err(EINVAL);
+ }
+
+ self.regulator_names = Some(names);
+
+ Ok(self)
+ }
+
+ /// Initializes required devices.
+ pub fn set_required_dev(mut self, dev: ARef<Device>, index: u32) -> Result<Self> {
+ if self.required_dev.is_some() {
+ return Err(EBUSY);
+ }
+
+ self.required_dev = Some((dev, index));
+ Ok(self)
+ }
+
+ /// Initializes supported hardware.
+ pub fn set_supported_hw(mut self, hw: KVec<u32>) -> Result<Self> {
+ if self.supported_hw.is_some() {
+ return Err(EBUSY);
+ }
+
+ if hw.is_empty() {
+ return Err(EINVAL);
+ }
+
+ self.supported_hw = Some(hw);
+ Ok(self)
+ }
+
+ /// Sets the configuration with the OPP core.
+ ///
+ /// The returned [`ConfigToken`] will remove the configuration when dropped.
+ pub fn set(self, dev: &Device) -> Result<ConfigToken> {
+ let (_clk_list, clk_names) = match &self.clk_names {
+ Some(x) => {
+ let list = to_c_str_array(x)?;
+ let ptr = list.as_ptr();
+ (Some(list), ptr)
+ }
+ None => (None, ptr::null()),
+ };
+
+ let (_regulator_list, regulator_names) = match &self.regulator_names {
+ Some(x) => {
+ let list = to_c_str_array(x)?;
+ let ptr = list.as_ptr();
+ (Some(list), ptr)
+ }
+ None => (None, ptr::null()),
+ };
+
+ let prop_name = self
+ .prop_name
+ .as_ref()
+ .map_or(ptr::null(), |p| p.as_char_ptr());
+
+ let (supported_hw, supported_hw_count) = self
+ .supported_hw
+ .as_ref()
+ .map_or((ptr::null(), 0), |hw| (hw.as_ptr(), hw.len() as u32));
+
+ let (required_dev, required_dev_index) = self
+ .required_dev
+ .as_ref()
+ .map_or((ptr::null_mut(), 0), |(dev, idx)| (dev.as_raw(), *idx));
+
+ let mut config = bindings::dev_pm_opp_config {
+ clk_names,
+ config_clks: if T::HAS_CONFIG_CLKS {
+ Some(Self::config_clks)
+ } else {
+ None
+ },
+ prop_name,
+ regulator_names,
+ config_regulators: if T::HAS_CONFIG_REGULATORS {
+ Some(Self::config_regulators)
+ } else {
+ None
+ },
+ supported_hw,
+ supported_hw_count,
+
+ required_dev,
+ required_dev_index,
+ };
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements. The OPP core guarantees not to access fields of [`Config`] after this call
+ // and so we don't need to save a copy of them for future use.
+ let ret = unsafe { bindings::dev_pm_opp_set_config(dev.as_raw(), &mut config) };
+ if ret < 0 {
+ Err(Error::from_errno(ret))
+ } else {
+ Ok(ConfigToken(ret))
+ }
+ }
+
+ // Config's clk callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn config_clks(
+ dev: *mut bindings::device,
+ opp_table: *mut bindings::opp_table,
+ opp: *mut bindings::dev_pm_opp,
+ _data: *mut kernel::ffi::c_void,
+ scaling_down: bool,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: 'dev' is guaranteed by the C code to be valid.
+ let dev = unsafe { Device::get_device(dev) };
+ T::config_clks(
+ &dev,
+ // SAFETY: 'opp_table' is guaranteed by the C code to be valid.
+ &unsafe { Table::from_raw_table(opp_table, &dev) },
+ // SAFETY: 'opp' is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp(opp)? },
+ scaling_down,
+ )
+ .map(|()| 0)
+ })
+ }
+
+ // Config's regulator callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn config_regulators(
+ dev: *mut bindings::device,
+ old_opp: *mut bindings::dev_pm_opp,
+ new_opp: *mut bindings::dev_pm_opp,
+ regulators: *mut *mut bindings::regulator,
+ count: kernel::ffi::c_uint,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: 'dev' is guaranteed by the C code to be valid.
+ let dev = unsafe { Device::get_device(dev) };
+ T::config_regulators(
+ &dev,
+ // SAFETY: 'old_opp' is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp(old_opp)? },
+ // SAFETY: 'new_opp' is guaranteed by the C code to be valid.
+ unsafe { OPP::from_raw_opp(new_opp)? },
+ regulators,
+ count,
+ )
+ .map(|()| 0)
+ })
+ }
+}
+
/// A reference-counted OPP table.
///
/// Rust abstraction for the C `struct opp_table`.
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 13/17] rust: cpufreq: Add initial abstractions for cpufreq framework
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (11 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 12/17] rust: opp: Add abstractions for the configuration options Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 14/17] rust: cpufreq: Extend abstractions for policy and driver ops Viresh Kumar
` (3 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
Danilo Krummrich, Viresh Kumar
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Introduce initial Rust abstractions for the cpufreq core. This includes
basic representations for cpufreq flags, relation types, and the cpufreq
table.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
MAINTAINERS | 1 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/cpufreq.c | 10 +
rust/helpers/helpers.c | 1 +
rust/kernel/cpufreq.rs | 341 ++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
6 files changed, 356 insertions(+)
create mode 100644 rust/helpers/cpufreq.c
create mode 100644 rust/kernel/cpufreq.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index 931e418f89ed..aa56eacbda71 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6142,6 +6142,7 @@ F: drivers/cpufreq/
F: include/linux/cpufreq.h
F: include/linux/sched/cpufreq.h
F: kernel/sched/cpufreq*.c
+F: rust/kernel/cpufreq.rs
F: tools/testing/selftests/cpufreq/
CPU HOTPLUG
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 529f22891e0b..7c1d78f68076 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -12,6 +12,7 @@
#include <linux/blkdev.h>
#include <linux/clk.h>
#include <linux/cpu.h>
+#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/cred.h>
#include <linux/device/faux.h>
diff --git a/rust/helpers/cpufreq.c b/rust/helpers/cpufreq.c
new file mode 100644
index 000000000000..7c1343c4d65e
--- /dev/null
+++ b/rust/helpers/cpufreq.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/cpufreq.h>
+
+#ifdef CONFIG_CPU_FREQ
+void rust_helper_cpufreq_register_em_with_opp(struct cpufreq_policy *policy)
+{
+ cpufreq_register_em_with_opp(policy);
+}
+#endif
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index ae595c9cd91b..df1fcfb3adf3 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -12,6 +12,7 @@
#include "build_assert.c"
#include "build_bug.c"
#include "clk.c"
+#include "cpufreq.c"
#include "cpumask.c"
#include "cred.c"
#include "device.c"
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
new file mode 100644
index 000000000000..19bb616d3625
--- /dev/null
+++ b/rust/kernel/cpufreq.rs
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! CPU frequency scaling.
+//!
+//! This module provides rust abstractions for interacting with the cpufreq subsystem.
+//!
+//! C header: [`include/linux/cpufreq.h`](srctree/include/linux/cpufreq.h)
+//!
+//! Reference: <https://docs.kernel.org/admin-guide/pm/cpufreq.html>
+
+use crate::{
+ bindings,
+ error::{code::*, to_result, Result},
+ ffi::c_ulong,
+ prelude::*,
+};
+
+use core::{
+ pin::Pin,
+};
+
+/// Default transition latency value in nanoseconds.
+pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32;
+
+/// CPU frequency driver flags.
+pub mod flags {
+ use crate::bindings;
+
+ /// Driver needs to update internal limits even if frequency remains unchanged.
+ pub const NEED_UPDATE_LIMITS: u16 = bindings::CPUFREQ_NEED_UPDATE_LIMITS as _;
+
+ /// Platform where constants like `loops_per_jiffy` are unaffected by frequency changes.
+ pub const CONST_LOOPS: u16 = bindings::CPUFREQ_CONST_LOOPS as _;
+
+ /// Register driver as a thermal cooling device automatically.
+ pub const IS_COOLING_DEV: u16 = bindings::CPUFREQ_IS_COOLING_DEV as _;
+
+ /// Supports multiple clock domains with per-policy governors in `cpu/cpuN/cpufreq/`.
+ pub const HAVE_GOVERNOR_PER_POLICY: u16 = bindings::CPUFREQ_HAVE_GOVERNOR_PER_POLICY as _;
+
+ /// Allows post-change notifications outside of the `target()` routine.
+ pub const ASYNC_NOTIFICATION: u16 = bindings::CPUFREQ_ASYNC_NOTIFICATION as _;
+
+ /// Ensure CPU starts at a valid frequency from the driver's freq-table.
+ pub const NEED_INITIAL_FREQ_CHECK: u16 = bindings::CPUFREQ_NEED_INITIAL_FREQ_CHECK as _;
+
+ /// Disallow governors with `dynamic_switching` capability.
+ pub const NO_AUTO_DYNAMIC_SWITCHING: u16 = bindings::CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING as _;
+}
+
+/// CPU frequency selection relations.
+///
+/// CPU frequency selection relations, each optionally marked as "efficient".
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Relation {
+ /// Select the lowest frequency at or above target.
+ Low(bool),
+ /// Select the highest frequency below or at target.
+ High(bool),
+ /// Select the closest frequency to the target.
+ Close(bool),
+}
+
+impl Relation {
+ // Construct from a C-compatible `u32` value.
+ fn new(val: u32) -> Result<Self> {
+ let efficient = val & bindings::CPUFREQ_RELATION_E != 0;
+
+ Ok(match val & !bindings::CPUFREQ_RELATION_E {
+ bindings::CPUFREQ_RELATION_L => Self::Low(efficient),
+ bindings::CPUFREQ_RELATION_H => Self::High(efficient),
+ bindings::CPUFREQ_RELATION_C => Self::Close(efficient),
+ _ => return Err(EINVAL),
+ })
+ }
+}
+
+impl From<Relation> for u32 {
+ // Convert to a C-compatible `u32` value.
+ fn from(rel: Relation) -> Self {
+ let (mut val, efficient) = match rel {
+ Relation::Low(e) => (bindings::CPUFREQ_RELATION_L, e),
+ Relation::High(e) => (bindings::CPUFREQ_RELATION_H, e),
+ Relation::Close(e) => (bindings::CPUFREQ_RELATION_C, e),
+ };
+
+ if efficient {
+ val |= bindings::CPUFREQ_RELATION_E;
+ }
+
+ val
+ }
+}
+
+/// Policy data.
+///
+/// Rust abstraction for the C `struct cpufreq_policy_data`.
+///
+/// # Invariants
+///
+/// A [`PolicyData`] instance always corresponds to a valid C `struct cpufreq_policy_data`.
+///
+/// The callers must ensure that the `struct cpufreq_policy_data` is valid for access and remains
+/// valid for the lifetime of the returned reference.
+#[repr(transparent)]
+pub struct PolicyData(Opaque<bindings::cpufreq_policy_data>);
+
+impl PolicyData {
+ /// Creates a mutable reference to an existing `struct cpufreq_policy_data` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ #[inline]
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpufreq_policy_data) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ /// Returns a raw pointer to the underlying C `cpufreq_policy_data`.
+ #[inline]
+ pub fn as_raw(&self) -> *mut bindings::cpufreq_policy_data {
+ self as *const _ as _
+ }
+
+ /// Wrapper for `cpufreq_generic_frequency_table_verify`.
+ #[inline]
+ pub fn generic_verify(&self) -> Result<()> {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ to_result(unsafe { bindings::cpufreq_generic_frequency_table_verify(self.as_raw()) })
+ }
+}
+
+/// CPU frequency table.
+///
+/// Rust abstraction for the C `struct cpufreq_frequency_table`.
+///
+/// # Invariants
+///
+/// A [`Table`] instance always corresponds to a valid C `struct cpufreq_frequency_table`.
+///
+/// The callers must ensure that the `struct cpufreq_frequency_table` is valid for access and
+/// remains valid for the lifetime of the returned reference.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to read a frequency value from [`Table`].
+///
+/// ```
+/// use kernel::cpufreq::Policy;
+///
+/// fn show_freq(policy: &Policy) {
+/// let table = policy.freq_table().unwrap();
+///
+/// // SAFETY: The index values passed are correct.
+/// unsafe {
+/// pr_info!("The frequency at index 0 is: {:?}\n", table.freq(0).unwrap());
+/// pr_info!("The flags at index 0 is: {}\n", table.flags(0));
+/// pr_info!("The data at index 0 is: {}\n", table.data(0));
+/// }
+/// }
+/// ```
+#[allow(dead_code)]
+#[repr(transparent)]
+pub struct Table(Opaque<bindings::cpufreq_frequency_table>);
+
+impl Table {
+ /// Creates a reference to an existing C `struct cpufreq_frequency_table` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ #[inline]
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpufreq_frequency_table) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Returns the raw mutable pointer to the C `struct cpufreq_frequency_table`.
+ #[inline]
+ pub fn as_raw(&self) -> *mut bindings::cpufreq_frequency_table {
+ self as *const _ as _
+ }
+
+ /// Returns frequency at `index` in the [`Table`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `index` corresponds to a valid table entry.
+ #[inline]
+ pub unsafe fn freq(&self, index: usize) -> Result<Hertz> {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+ // guaranteed to be valid by the safety requirements of the function.
+ Ok(Hertz::from_khz(unsafe {
+ (*self.as_raw().add(index)).frequency.try_into()?
+ }))
+ }
+
+ /// Returns flags at `index` in the [`Table`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `index` corresponds to a valid table entry.
+ #[inline]
+ pub unsafe fn flags(&self, index: usize) -> u32 {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+ // guaranteed to be valid by the safety requirements of the function.
+ unsafe { (*self.as_raw().add(index)).flags }
+ }
+
+ /// Returns data at `index` in the [`Table`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `index` corresponds to a valid table entry.
+ #[inline]
+ pub unsafe fn data(&self, index: usize) -> u32 {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+ // guaranteed to be valid by the safety requirements of the function.
+ unsafe { (*self.as_raw().add(index)).driver_data }
+ }
+}
+
+/// CPU frequency table owned and pinned in memory, created from a [`TableBuilder`].
+pub struct TableBox {
+ #[allow(dead_code)]
+ entries: Pin<KVec<bindings::cpufreq_frequency_table>>,
+}
+
+impl TableBox {
+ /// Constructs a new [`TableBox`] from a [`KVec`] of entries.
+ ///
+ /// # Errors
+ ///
+ /// Returns `EINVAL` if the entries list is empty.
+ #[inline]
+ fn new(entries: KVec<bindings::cpufreq_frequency_table>) -> Result<Self> {
+ if entries.is_empty() {
+ return Err(EINVAL);
+ }
+
+ Ok(Self {
+ // Pin the entries to memory, since we are passing its pointer to the C code.
+ entries: Pin::new(entries),
+ })
+ }
+
+ /// Returns a raw pointer to the underlying C `cpufreq_frequency_table`.
+ #[inline]
+ fn as_raw(&self) -> *const bindings::cpufreq_frequency_table {
+ // The pointer is valid until the table gets dropped.
+ self.entries.as_ptr()
+ }
+}
+
+impl Deref for TableBox {
+ type Target = Table;
+
+ fn deref(&self) -> &Self::Target {
+ // SAFETY: The caller owns TableBox, it is safe to deref.
+ unsafe { Self::Target::from_raw(self.as_raw()) }
+ }
+}
+
+/// CPU frequency table builder.
+///
+/// This is used by the CPU frequency drivers to build a frequency table dynamically.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create a CPU frequency table.
+///
+/// ```
+/// use kernel::cpufreq::TableBuilder;
+/// use kernel::clk::Hertz;
+///
+/// let mut builder = TableBuilder::new();
+///
+/// // Adds few entries to the table.
+/// builder.add(Hertz::from_mhz(700), 0, 1).unwrap();
+/// builder.add(Hertz::from_mhz(800), 2, 3).unwrap();
+/// builder.add(Hertz::from_mhz(900), 4, 5).unwrap();
+/// builder.add(Hertz::from_ghz(1), 6, 7).unwrap();
+///
+/// let table = builder.to_table().unwrap();
+///
+/// // SAFETY: The index values passed are correct.
+/// unsafe {
+/// assert_eq!(table.freq(0), Ok(Hertz::from_mhz(700)));
+/// assert_eq!(table.flags(0), 0);
+/// assert_eq!(table.data(0), 1);
+///
+/// assert_eq!(table.freq(2), Ok(Hertz::from_mhz(900)));
+/// assert_eq!(table.flags(2), 4);
+/// assert_eq!(table.data(2), 5);
+/// }
+/// ```
+#[derive(Default)]
+#[repr(transparent)]
+pub struct TableBuilder {
+ entries: KVec<bindings::cpufreq_frequency_table>,
+}
+
+impl TableBuilder {
+ /// Creates a new instance of [`TableBuilder`].
+ #[inline]
+ pub fn new() -> Self {
+ Self {
+ entries: KVec::new(),
+ }
+ }
+
+ /// Adds a new entry to the table.
+ pub fn add(&mut self, freq: Hertz, flags: u32, driver_data: u32) -> Result<()> {
+ // Adds the new entry at the end of the vector.
+ Ok(self.entries.push(
+ bindings::cpufreq_frequency_table {
+ flags,
+ driver_data,
+ frequency: freq.as_khz() as u32,
+ },
+ GFP_KERNEL,
+ )?)
+ }
+
+ /// Consumes the [`TableBuilder`] and returns [`TableBox`].
+ pub fn to_table(mut self) -> Result<TableBox> {
+ // Add last entry to the table.
+ self.add(Hertz(c_ulong::MAX), 0, 0)?;
+
+ TableBox::new(self.entries)
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 11d333c8c673..871fcdc09b35 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -45,6 +45,8 @@
#[cfg(CONFIG_COMMON_CLK)]
pub mod clk;
pub mod cpu;
+#[cfg(CONFIG_CPU_FREQ)]
+pub mod cpufreq;
pub mod cpumask;
pub mod cred;
pub mod device;
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 14/17] rust: cpufreq: Extend abstractions for policy and driver ops
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (12 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 13/17] rust: cpufreq: Add initial abstractions for cpufreq framework Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration Viresh Kumar
` (2 subsequent siblings)
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Extend the cpufreq abstractions to include support for policy handling
and driver operations.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/cpufreq.rs | 455 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 454 insertions(+), 1 deletion(-)
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 19bb616d3625..3e9ded655d46 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -10,15 +10,24 @@
use crate::{
bindings,
- error::{code::*, to_result, Result},
+ clk::{Clk, Hertz},
+ cpumask,
+ device::Device,
+ error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
ffi::c_ulong,
prelude::*,
+ types::ForeignOwnable,
+ types::Opaque,
};
use core::{
+ ops::{Deref, DerefMut},
pin::Pin,
+ ptr::self,
};
+use macros::vtable;
+
/// Default transition latency value in nanoseconds.
pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32;
@@ -339,3 +348,447 @@ pub fn to_table(mut self) -> Result<TableBox> {
TableBox::new(self.entries)
}
}
+
+/// CPU frequency policy.
+///
+/// Rust abstraction for the C `struct cpufreq_policy`.
+///
+/// # Invariants
+///
+/// A [`Policy`] instance always corresponds to a valid C `struct cpufreq_policy`.
+///
+/// The callers must ensure that the `struct cpufreq_policy` is valid for access and remains valid
+/// for the lifetime of the returned reference.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create a CPU frequency table.
+///
+/// ```
+/// use kernel::cpufreq::{ETERNAL_LATENCY_NS, Policy};
+///
+/// fn update_policy(policy: &mut Policy) {
+/// policy
+/// .set_dvfs_possible_from_any_cpu(true)
+/// .set_fast_switch_possible(true)
+/// .set_transition_latency_ns(ETERNAL_LATENCY_NS);
+///
+/// pr_info!("The policy details are: {:?}\n", (policy.cpu(), policy.cur()));
+/// }
+/// ```
+#[repr(transparent)]
+pub struct Policy(Opaque<bindings::cpufreq_policy>);
+
+impl Policy {
+ /// Creates a reference to an existing `struct cpufreq_policy` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ #[inline]
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpufreq_policy) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Creates a mutable reference to an existing `struct cpufreq_policy` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ #[inline]
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpufreq_policy) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ // Returns a raw mutable pointer to the C `struct cpufreq_policy`.
+ #[inline]
+ fn as_raw(&self) -> *mut bindings::cpufreq_policy {
+ self as *const _ as _
+ }
+
+ #[inline]
+ fn as_ref(&self) -> &bindings::cpufreq_policy {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ unsafe { &*self.as_raw() }
+ }
+
+ #[inline]
+ fn as_mut_ref(&mut self) -> &mut bindings::cpufreq_policy {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ unsafe { &mut *self.as_raw() }
+ }
+
+ /// Returns the primary CPU for the [`Policy`].
+ #[inline]
+ pub fn cpu(&self) -> u32 {
+ self.as_ref().cpu
+ }
+
+ /// Returns the minimum frequency for the [`Policy`].
+ #[inline]
+ pub fn min(&self) -> Hertz {
+ Hertz::from_khz(self.as_ref().min as usize)
+ }
+
+ /// Set the minimum frequency for the [`Policy`].
+ #[inline]
+ pub fn set_min(&mut self, min: Hertz) -> &mut Self {
+ self.as_mut_ref().min = min.as_khz() as u32;
+ self
+ }
+
+ /// Returns the maximum frequency for the [`Policy`].
+ #[inline]
+ pub fn max(&self) -> Hertz {
+ Hertz::from_khz(self.as_ref().max as usize)
+ }
+
+ /// Set the maximum frequency for the [`Policy`].
+ #[inline]
+ pub fn set_max(&mut self, max: Hertz) -> &mut Self {
+ self.as_mut_ref().max = max.as_khz() as u32;
+ self
+ }
+
+ /// Returns the current frequency for the [`Policy`].
+ #[inline]
+ pub fn cur(&self) -> Hertz {
+ Hertz::from_khz(self.as_ref().cur as usize)
+ }
+
+ /// Returns the suspend frequency for the [`Policy`].
+ #[inline]
+ pub fn suspend_freq(&self) -> Hertz {
+ Hertz::from_khz(self.as_ref().suspend_freq as usize)
+ }
+
+ /// Sets the suspend frequency for the [`Policy`].
+ #[inline]
+ pub fn set_suspend_freq(&mut self, freq: Hertz) -> &mut Self {
+ self.as_mut_ref().suspend_freq = freq.as_khz() as u32;
+ self
+ }
+
+ /// Provides a wrapper to the generic suspend routine.
+ #[inline]
+ pub fn generic_suspend(&mut self) -> Result<()> {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ to_result(unsafe { bindings::cpufreq_generic_suspend(self.as_mut_ref()) })
+ }
+
+ /// Provides a wrapper to the generic get routine.
+ #[inline]
+ pub fn generic_get(&self) -> Result<u32> {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) })
+ }
+
+ /// Provides a wrapper to the register with energy model using the OPP core.
+ #[cfg(CONFIG_PM_OPP)]
+ #[inline]
+ pub fn register_em_opp(&mut self) {
+ // SAFETY: By the type invariant, the pointer stored in `self` is valid.
+ unsafe { bindings::cpufreq_register_em_with_opp(self.as_mut_ref()) };
+ }
+
+ /// Gets [`cpumask::Cpumask`] for a cpufreq [`Policy`].
+ #[inline]
+ pub fn cpus(&mut self) -> &mut cpumask::Cpumask {
+ // SAFETY: The pointer to `cpus` is valid for writing and remains valid for the lifetime of
+ // the returned reference.
+ unsafe { cpumask::CpumaskVar::from_raw_mut(&mut self.as_mut_ref().cpus) }
+ }
+
+ /// Sets clock for the [`Policy`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must guarantee that the returned [`Clk`] is not dropped while it is getting used
+ /// by the C code.
+ pub unsafe fn set_clk(&mut self, dev: &Device, name: Option<&CStr>) -> Result<Clk> {
+ let clk = Clk::get(dev, name)?;
+ self.as_mut_ref().clk = clk.as_raw();
+ Ok(clk)
+ }
+
+ /// Allows / disallows frequency switching code to run on any CPU.
+ #[inline]
+ pub fn set_dvfs_possible_from_any_cpu(&mut self, val: bool) -> &mut Self {
+ self.as_mut_ref().dvfs_possible_from_any_cpu = val;
+ self
+ }
+
+ /// Returns if fast switching of frequencies is possible or not.
+ #[inline]
+ pub fn fast_switch_possible(&self) -> bool {
+ self.as_ref().fast_switch_possible
+ }
+
+ /// Enables / disables fast frequency switching.
+ #[inline]
+ pub fn set_fast_switch_possible(&mut self, val: bool) -> &mut Self {
+ self.as_mut_ref().fast_switch_possible = val;
+ self
+ }
+
+ /// Sets transition latency (in nanoseconds) for the [`Policy`].
+ #[inline]
+ pub fn set_transition_latency_ns(&mut self, latency_ns: u32) -> &mut Self {
+ self.as_mut_ref().cpuinfo.transition_latency = latency_ns;
+ self
+ }
+
+ /// Sets cpuinfo `min_freq`.
+ #[inline]
+ pub fn set_cpuinfo_min_freq(&mut self, min_freq: Hertz) -> &mut Self {
+ self.as_mut_ref().cpuinfo.min_freq = min_freq.as_khz() as u32;
+ self
+ }
+
+ /// Sets cpuinfo `max_freq`.
+ #[inline]
+ pub fn set_cpuinfo_max_freq(&mut self, max_freq: Hertz) -> &mut Self {
+ self.as_mut_ref().cpuinfo.max_freq = max_freq.as_khz() as u32;
+ self
+ }
+
+ /// Set `transition_delay_us`, i.e. the minimum time between successive frequency change
+ /// requests.
+ #[inline]
+ pub fn set_transition_delay_us(&mut self, transition_delay_us: u32) -> &mut Self {
+ self.as_mut_ref().transition_delay_us = transition_delay_us;
+ self
+ }
+
+ /// Returns reference to the CPU frequency [`Table`] for the [`Policy`].
+ pub fn freq_table(&self) -> Result<&Table> {
+ if self.as_ref().freq_table.is_null() {
+ return Err(EINVAL);
+ }
+
+ // SAFETY: The `freq_table` is guaranteed to be valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ Ok(unsafe { Table::from_raw(self.as_ref().freq_table) })
+ }
+
+ /// Sets the CPU frequency [`Table`] for the [`Policy`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must guarantee that the [`Table`] is not dropped while it is getting used by the
+ /// C code.
+ #[inline]
+ pub unsafe fn set_freq_table(&mut self, table: &Table) -> &mut Self {
+ self.as_mut_ref().freq_table = table.as_raw();
+ self
+ }
+
+ /// Returns the [`Policy`]'s private data.
+ pub fn data<T: ForeignOwnable>(&mut self) -> Option<<T>::Borrowed<'_>> {
+ if self.as_ref().driver_data.is_null() {
+ None
+ } else {
+ // SAFETY: The data is earlier set from [`set_data`].
+ Some(unsafe { T::borrow(self.as_ref().driver_data) })
+ }
+ }
+
+ // Sets the private data of the [`Policy`] using a foreign-ownable wrapper.
+ //
+ // # Errors
+ //
+ // Returns `EBUSY` if private data is already set.
+ fn set_data<T: ForeignOwnable>(&mut self, data: T) -> Result<()> {
+ if self.as_ref().driver_data.is_null() {
+ // Transfer the ownership of the data to the foreign interface.
+ self.as_mut_ref().driver_data = <T as ForeignOwnable>::into_foreign(data) as _;
+ Ok(())
+ } else {
+ Err(EBUSY)
+ }
+ }
+
+ // Clears and returns ownership of the private data.
+ fn clear_data<T: ForeignOwnable>(&mut self) -> Option<T> {
+ if self.as_ref().driver_data.is_null() {
+ None
+ } else {
+ let data = Some(
+ // SAFETY: The data is earlier set by us from [`set_data`]. It is safe to take
+ // back the ownership of the data from the foreign interface.
+ unsafe { <T as ForeignOwnable>::from_foreign(self.as_ref().driver_data) },
+ );
+ self.as_mut_ref().driver_data = ptr::null_mut();
+ data
+ }
+ }
+}
+
+// CPU frequency policy created from a CPU number.
+//
+// This struct represents the CPU frequency policy obtained for a specific CPU, providing safe
+// access to the underlying `cpufreq_policy` and ensuring proper cleanup when the `PolicyCpu` is
+// dropped.
+struct PolicyCpu<'a>(&'a mut Policy);
+
+impl<'a> PolicyCpu<'a> {
+ fn from_cpu(cpu: u32) -> Result<Self> {
+ // SAFETY: It is safe to call `cpufreq_cpu_get` for any valid CPU.
+ let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?;
+
+ Ok(Self(
+ // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of
+ // the returned reference.
+ unsafe { Policy::from_raw_mut(ptr) },
+ ))
+ }
+}
+
+impl<'a> Deref for PolicyCpu<'a> {
+ type Target = Policy;
+
+ fn deref(&self) -> &Self::Target {
+ self.0
+ }
+}
+
+impl<'a> DerefMut for PolicyCpu<'a> {
+ fn deref_mut(&mut self) -> &mut Policy {
+ self.0
+ }
+}
+
+impl<'a> Drop for PolicyCpu<'a> {
+ fn drop(&mut self) {
+ // SAFETY: The underlying pointer is guaranteed to be valid for the lifetime of `self`.
+ unsafe { bindings::cpufreq_cpu_put(self.0.as_raw()) };
+ }
+}
+
+/// CPU frequency driver.
+///
+/// Implement this trait to provide a CPU frequency driver and its callbacks.
+///
+/// Reference: <https://docs.kernel.org/cpu-freq/cpu-drivers.html>
+#[vtable]
+pub trait Driver {
+ /// Driver specific data.
+ ///
+ /// Corresponds to the data retrieved via the kernel's `cpufreq_get_driver_data` function.
+ ///
+ /// Require `Data` to implement `ForeignOwnable`. We guarantee to never move the underlying
+ /// wrapped data structure.
+ type Data: ForeignOwnable;
+
+ /// Policy specific data.
+ ///
+ /// Require that `PData` implements `ForeignOwnable`. We guarantee to never move the underlying
+ /// wrapped data structure.
+ type PData: ForeignOwnable;
+
+ /// Driver's `init` callback.
+ fn init(policy: &mut Policy) -> Result<Self::PData>;
+
+ /// Driver's `exit` callback.
+ fn exit(_policy: &mut Policy, _data: Option<Self::PData>) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `online` callback.
+ fn online(_policy: &mut Policy) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `offline` callback.
+ fn offline(_policy: &mut Policy) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `suspend` callback.
+ fn suspend(_policy: &mut Policy) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `resume` callback.
+ fn resume(_policy: &mut Policy) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `ready` callback.
+ fn ready(_policy: &mut Policy) {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `verify` callback.
+ fn verify(data: &mut PolicyData) -> Result<()>;
+
+ /// Driver's `setpolicy` callback.
+ fn setpolicy(_policy: &mut Policy) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `target` callback.
+ fn target(_policy: &mut Policy, _target_freq: u32, _relation: Relation) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `target_index` callback.
+ fn target_index(_policy: &mut Policy, _index: u32) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `fast_switch` callback.
+ fn fast_switch(_policy: &mut Policy, _target_freq: u32) -> u32 {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `adjust_perf` callback.
+ fn adjust_perf(_policy: &mut Policy, _min_perf: usize, _target_perf: usize, _capacity: usize) {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `get_intermediate` callback.
+ fn get_intermediate(_policy: &mut Policy, _index: u32) -> u32 {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `target_intermediate` callback.
+ fn target_intermediate(_policy: &mut Policy, _index: u32) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `get` callback.
+ fn get(_policy: &mut Policy) -> Result<u32> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `update_limits` callback.
+ fn update_limits(_policy: &mut Policy) {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `bios_limit` callback.
+ fn bios_limit(_policy: &mut Policy, _limit: &mut u32) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `set_boost` callback.
+ fn set_boost(_policy: &mut Policy, _state: i32) -> Result<()> {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+
+ /// Driver's `register_em` callback.
+ fn register_em(_policy: &mut Policy) {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+}
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (13 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 14/17] rust: cpufreq: Extend abstractions for policy and driver ops Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 11:58 ` Danilo Krummrich
2025-04-11 10:55 ` [PATCH V9 16/17] rust: opp: Extend OPP abstractions with cpufreq support Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 17/17] cpufreq: Add Rust-based cpufreq-dt driver Viresh Kumar
16 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Extend the cpufreq abstractions to support driver registration from
Rust.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/cpufreq.rs | 530 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 528 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 3e9ded655d46..4194b9558413 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -13,7 +13,8 @@
clk::{Clk, Hertz},
cpumask,
device::Device,
- error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
+ devres::Devres,
+ error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
ffi::c_ulong,
prelude::*,
types::ForeignOwnable,
@@ -21,9 +22,11 @@
};
use core::{
+ cell::UnsafeCell,
+ marker::PhantomData,
ops::{Deref, DerefMut},
pin::Pin,
- ptr::self,
+ ptr,
};
use macros::vtable;
@@ -792,3 +795,526 @@ fn register_em(_policy: &mut Policy) {
build_error!(VTABLE_DEFAULT_ERROR)
}
}
+
+/// CPU frequency driver Registration.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to register a cpufreq driver.
+///
+/// ```
+/// use kernel::{
+/// c_str,
+/// cpu, cpufreq,
+/// device::Device,
+/// macros::vtable,
+/// sync::Arc,
+/// };
+/// struct FooDevice;
+///
+/// #[derive(Default)]
+/// struct FooDriver;
+///
+/// #[vtable]
+/// impl cpufreq::Driver for FooDriver {
+/// type Data = ();
+/// type PData = Arc<FooDevice>;
+///
+/// fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
+/// // Initialize here
+/// Ok(Arc::new(FooDevice, GFP_KERNEL)?)
+/// }
+///
+/// fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
+/// Ok(())
+/// }
+///
+/// fn suspend(policy: &mut cpufreq::Policy) -> Result<()> {
+/// policy.generic_suspend()
+/// }
+///
+/// fn verify(data: &mut cpufreq::PolicyData) -> Result<()> {
+/// data.generic_verify()
+/// }
+///
+/// fn target_index(policy: &mut cpufreq::Policy, index: u32) -> Result<()> {
+/// // Update CPU frequency
+/// Ok(())
+/// }
+///
+/// fn get(policy: &mut cpufreq::Policy) -> Result<u32> {
+/// policy.generic_get()
+/// }
+/// }
+///
+/// fn foo_probe(dev: &Device) {
+/// cpufreq::Registration::<FooDriver>::new_foreign_owned(
+/// dev,
+/// c_str!("cpufreq-foo"),
+/// (),
+/// cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
+/// true,
+/// ).unwrap();
+/// }
+/// ```
+pub struct Registration<T: Driver> {
+ drv: KBox<UnsafeCell<bindings::cpufreq_driver>>,
+ _p: PhantomData<T>,
+}
+
+// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
+// or CPUs, so it is safe to share it.
+unsafe impl<T: Driver> Sync for Registration<T> {}
+
+#[allow(clippy::non_send_fields_in_send_ty)]
+// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any
+// thread. Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is
+// okay to move `Registration` to different threads.
+unsafe impl<T: Driver> Send for Registration<T> {}
+
+impl<T: Driver> Registration<T> {
+ /// Registers a CPU frequency driver with the cpufreq core.
+ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
+ // Required due to Rust 1.82's stricter handling of `unsafe` in mutable statics. The
+ // `unsafe` blocks aren't required anymore with later versions.
+ #![allow(unused_unsafe)]
+
+ let mut drv = KBox::new(
+ UnsafeCell::new(bindings::cpufreq_driver::default()),
+ GFP_KERNEL,
+ )?;
+ let drv_ref = drv.get_mut();
+
+ // Account for the trailing null byte.
+ let len = name.len() + 1;
+ if len > drv_ref.name.len() {
+ return Err(EINVAL);
+ };
+
+ // SAFETY: `name` is a valid `CStr`, and we are copying it to an array of equal or larger
+ // size.
+ let name = unsafe { &*(name.as_bytes_with_nul() as *const [u8]) };
+ drv_ref.name[..len].copy_from_slice(name);
+
+ drv_ref.boost_enabled = boost;
+ drv_ref.flags = flags;
+
+ // Initialize mandatory callbacks.
+ drv_ref.init = Some(Self::init_callback);
+ drv_ref.verify = Some(Self::verify_callback);
+
+ // Initialize optional callbacks based on the traits of `T`.
+ drv_ref.setpolicy = if T::HAS_SETPOLICY {
+ Some(Self::setpolicy_callback)
+ } else {
+ None
+ };
+ drv_ref.target = if T::HAS_TARGET {
+ Some(Self::target_callback)
+ } else {
+ None
+ };
+ drv_ref.target_index = if T::HAS_TARGET_INDEX {
+ Some(Self::target_index_callback)
+ } else {
+ None
+ };
+ drv_ref.fast_switch = if T::HAS_FAST_SWITCH {
+ Some(Self::fast_switch_callback)
+ } else {
+ None
+ };
+ drv_ref.adjust_perf = if T::HAS_ADJUST_PERF {
+ Some(Self::adjust_perf_callback)
+ } else {
+ None
+ };
+ drv_ref.get_intermediate = if T::HAS_GET_INTERMEDIATE {
+ Some(Self::get_intermediate_callback)
+ } else {
+ None
+ };
+ drv_ref.target_intermediate = if T::HAS_TARGET_INTERMEDIATE {
+ Some(Self::target_intermediate_callback)
+ } else {
+ None
+ };
+ drv_ref.get = if T::HAS_GET {
+ Some(Self::get_callback)
+ } else {
+ None
+ };
+ drv_ref.update_limits = if T::HAS_UPDATE_LIMITS {
+ Some(Self::update_limits_callback)
+ } else {
+ None
+ };
+ drv_ref.bios_limit = if T::HAS_BIOS_LIMIT {
+ Some(Self::bios_limit_callback)
+ } else {
+ None
+ };
+ drv_ref.online = if T::HAS_ONLINE {
+ Some(Self::online_callback)
+ } else {
+ None
+ };
+ drv_ref.offline = if T::HAS_OFFLINE {
+ Some(Self::offline_callback)
+ } else {
+ None
+ };
+ drv_ref.exit = if T::HAS_EXIT {
+ Some(Self::exit_callback)
+ } else {
+ None
+ };
+ drv_ref.suspend = if T::HAS_SUSPEND {
+ Some(Self::suspend_callback)
+ } else {
+ None
+ };
+ drv_ref.resume = if T::HAS_RESUME {
+ Some(Self::resume_callback)
+ } else {
+ None
+ };
+ drv_ref.ready = if T::HAS_READY {
+ Some(Self::ready_callback)
+ } else {
+ None
+ };
+ drv_ref.set_boost = if T::HAS_SET_BOOST {
+ Some(Self::set_boost_callback)
+ } else {
+ None
+ };
+ drv_ref.register_em = if T::HAS_REGISTER_EM {
+ Some(Self::register_em_callback)
+ } else {
+ None
+ };
+
+ // Set driver data before registering the driver, as the cpufreq core calls few callbacks
+ // before `cpufreq_register_driver` returns.
+ Self::set_data(drv_ref, data)?;
+
+ // SAFETY: It is safe to register the driver with the cpufreq core in the kernel C code.
+ to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
+
+ Ok(Self {
+ drv,
+ _p: PhantomData,
+ })
+ }
+
+ /// Same as [`Registration::new`], but does not return a [`Registration`] instance.
+ ///
+ /// Instead the [`Registration`] is owned by [`Devres`] and will be revoked / dropped, once the
+ /// device is detached.
+ pub fn new_foreign_owned(
+ dev: &Device,
+ name: &'static CStr,
+ data: T::Data,
+ flags: u16,
+ boost: bool,
+ ) -> Result<()> {
+ Devres::new_foreign_owned(dev, Self::new(name, data, flags, boost)?, GFP_KERNEL)?;
+ Ok(())
+ }
+
+ // Sets the `Data` for the CPU frequency driver.
+ fn set_data(drv: &mut bindings::cpufreq_driver, data: T::Data) -> Result<()> {
+ if drv.driver_data.is_null() {
+ // Transfer the ownership of the data to the C code.
+ drv.driver_data = <T::Data as ForeignOwnable>::into_foreign(data) as _;
+ Ok(())
+ } else {
+ Err(EBUSY)
+ }
+ }
+
+ /// Returns borrowed `Data` previously set for the CPU frequency driver.
+ pub fn data(&mut self) -> Option<<T::Data as ForeignOwnable>::Borrowed<'static>> {
+ let drv = self.drv.get_mut();
+
+ if drv.driver_data.is_null() {
+ None
+ } else {
+ // SAFETY: The data is earlier set by us from `set_data`.
+ Some(unsafe { <T::Data as ForeignOwnable>::borrow(drv.driver_data) })
+ }
+ }
+
+ // Clears and returns the `Data` for the CPU frequency driver.
+ fn clear_data(&mut self) -> Option<T::Data> {
+ let drv = self.drv.get_mut();
+
+ if drv.driver_data.is_null() {
+ None
+ } else {
+ // SAFETY: The data is earlier set by us from `set_data`.
+ let data = Some(unsafe { <T::Data as ForeignOwnable>::from_foreign(drv.driver_data) });
+ drv.driver_data = ptr::null_mut();
+ data
+ }
+ }
+}
+
+// CPU frequency driver callbacks.
+impl<T: Driver> Registration<T> {
+ // Driver's `init` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+
+ let data = T::init(policy)?;
+ policy.set_data(data)?;
+ Ok(0)
+ })
+ }
+
+ // Driver's `exit` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+
+ let data = policy.clear_data();
+ let _ = T::exit(policy, data);
+ }
+
+ // Driver's `online` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::online(policy).map(|()| 0)
+ })
+ }
+
+ // Driver's `offline` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::offline(policy).map(|()| 0)
+ })
+ }
+
+ // Driver's `suspend` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::suspend(policy).map(|()| 0)
+ })
+ }
+
+ // Driver's `resume` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::resume(policy).map(|()| 0)
+ })
+ }
+
+ // Driver's `ready` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::ready(policy);
+ }
+
+ // Driver's `verify` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let data = unsafe { PolicyData::from_raw_mut(ptr) };
+ T::verify(data).map(|()| 0)
+ })
+ }
+
+ // Driver's `setpolicy` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::setpolicy(policy).map(|()| 0)
+ })
+ }
+
+ // Driver's `target` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn target_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ target_freq: u32,
+ relation: u32,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::target(policy, target_freq, Relation::new(relation)?).map(|()| 0)
+ })
+ }
+
+ // Driver's `target_index` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn target_index_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ index: u32,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::target_index(policy, index).map(|()| 0)
+ })
+ }
+
+ // Driver's `fast_switch` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn fast_switch_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ target_freq: u32,
+ ) -> kernel::ffi::c_uint {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::fast_switch(policy, target_freq)
+ }
+
+ // Driver's `adjust_perf` callback.
+ extern "C" fn adjust_perf_callback(
+ cpu: u32,
+ min_perf: usize,
+ target_perf: usize,
+ capacity: usize,
+ ) {
+ if let Ok(mut policy) = PolicyCpu::from_cpu(cpu) {
+ T::adjust_perf(&mut policy, min_perf, target_perf, capacity);
+ }
+ }
+
+ // Driver's `get_intermediate` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn get_intermediate_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ index: u32,
+ ) -> kernel::ffi::c_uint {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::get_intermediate(policy, index)
+ }
+
+ // Driver's `target_intermediate` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn target_intermediate_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ index: u32,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::target_intermediate(policy, index).map(|()| 0)
+ })
+ }
+
+ // Driver's `get` callback.
+ extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint {
+ PolicyCpu::from_cpu(cpu).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f))
+ }
+
+ // Driver's `update_limit` callback.
+ extern "C" fn update_limits_callback(cpu: u32) {
+ if let Ok(mut policy) = PolicyCpu::from_cpu(cpu) {
+ T::update_limits(&mut policy);
+ }
+ }
+
+ // Driver's `bios_limit` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int {
+ from_result(|| {
+ let mut policy = PolicyCpu::from_cpu(cpu as u32)?;
+
+ // SAFETY: `limit` is guaranteed by the C code to be valid.
+ T::bios_limit(&mut policy, &mut (unsafe { *limit })).map(|()| 0)
+ })
+ }
+
+ // Driver's `set_boost` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn set_boost_callback(
+ ptr: *mut bindings::cpufreq_policy,
+ state: i32,
+ ) -> kernel::ffi::c_int {
+ from_result(|| {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::set_boost(policy, state).map(|()| 0)
+ })
+ }
+
+ // Driver's `register_em` callback.
+ //
+ // SAFETY: Called from C. Inputs must be valid pointers.
+ extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) {
+ // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
+ // lifetime of `policy`.
+ let policy = unsafe { Policy::from_raw_mut(ptr) };
+ T::register_em(policy);
+ }
+}
+
+impl<T: Driver> Drop for Registration<T> {
+ // Removes the `Registration` from the kernel, if it has initialized successfully earlier.
+ fn drop(&mut self) {
+ let drv = self.drv.get_mut();
+
+ // SAFETY: The driver was earlier registered from `new`.
+ unsafe { bindings::cpufreq_unregister_driver(drv) };
+
+ // Free data
+ drop(self.clear_data());
+ }
+}
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-11 10:55 ` [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration Viresh Kumar
@ 2025-04-11 11:58 ` Danilo Krummrich
2025-04-14 8:47 ` Viresh Kumar
0 siblings, 1 reply; 31+ messages in thread
From: Danilo Krummrich @ 2025-04-11 11:58 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Fri, Apr 11, 2025 at 04:25:14PM +0530, Viresh Kumar wrote:
> +pub struct Registration<T: Driver> {
> + drv: KBox<UnsafeCell<bindings::cpufreq_driver>>,
> + _p: PhantomData<T>,
> +}
> +
> +// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
> +// or CPUs, so it is safe to share it.
> +unsafe impl<T: Driver> Sync for Registration<T> {}
> +
> +#[allow(clippy::non_send_fields_in_send_ty)]
> +// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any
> +// thread. Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is
> +// okay to move `Registration` to different threads.
> +unsafe impl<T: Driver> Send for Registration<T> {}
> +
> +impl<T: Driver> Registration<T> {
> + /// Registers a CPU frequency driver with the cpufreq core.
> + pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
Do you really need the private data? It seems to be used by only very few
drivers in C either.
If yes, I think you have to split this up into a CpufreqDriver structure and a
separate Registration. Otherwise you won't ever get access to the private data
again, after Registration::new_foreign_owned().
Note that we typically want Registration::new_foreign_owned(), because it
implies the guaranteed "fence" for where we can safely consider a device to be
bound. If we'd give out a Registration instance instead, the driver can
arbitrarily extend its lifetime across the remove() boundary.
If no, it seems to me that you can even avoid allocating a struct cpufreq_driver
dynamically and make it const instead. The fields name, boost_enabled and flags
could be required consts in your cpufreq::Driver trait.
^ permalink raw reply [flat|nested] 31+ messages in thread* Re: [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-11 11:58 ` Danilo Krummrich
@ 2025-04-14 8:47 ` Viresh Kumar
2025-04-14 9:39 ` Danilo Krummrich
0 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-14 8:47 UTC (permalink / raw)
To: Danilo Krummrich
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On 11-04-25, 13:58, Danilo Krummrich wrote:
> On Fri, Apr 11, 2025 at 04:25:14PM +0530, Viresh Kumar wrote:
> > +impl<T: Driver> Registration<T> {
> > + /// Registers a CPU frequency driver with the cpufreq core.
> > + pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
>
> Do you really need the private data? It seems to be used by only very few
> drivers in C either.
Yes, only a few of them are setting it to a value other than `pdev`.
Maybe we can avoid it for the time being and come back to this when a
driver really wants it.
> If no, it seems to me that you can even avoid allocating a struct cpufreq_driver
> dynamically and make it const instead.
I am not sure if I understood your suggestion. The Registration::new()
method still updates the instance of cpufreq_driver before passing it
to the C cpufreq core.
I have tried to fix the other issues though.
--
viresh
diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
index 751be33c0218..831269bdeabf 100644
--- a/drivers/cpufreq/rcpufreq_dt.rs
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -59,7 +59,10 @@ impl opp::ConfigOps for CPUFreqDTDriver {}
#[vtable]
impl cpufreq::Driver for CPUFreqDTDriver {
- type Data = ();
+ const NAME: &CStr = c_str!("cpufreq-dt");
+ const FLAGS: u16 = cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV;
+ const BOOST_ENABLED: bool = true;
+
type PData = Arc<CPUFreqDTDevice>;
fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
@@ -213,13 +216,7 @@ fn probe(
pdev: &platform::Device<Core>,
_id_info: Option<&Self::IdInfo>,
) -> Result<Pin<KBox<Self>>> {
- cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(
- pdev.as_ref(),
- c_str!("cpufreq-dt"),
- (),
- cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
- true,
- )?;
+ cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(pdev.as_ref())?;
let drvdata = KBox::new(Self {}, GFP_KERNEL)?;
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 4194b9558413..9b275d4d3eb6 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -685,13 +685,14 @@ fn drop(&mut self) {
/// Reference: <https://docs.kernel.org/cpu-freq/cpu-drivers.html>
#[vtable]
pub trait Driver {
- /// Driver specific data.
- ///
- /// Corresponds to the data retrieved via the kernel's `cpufreq_get_driver_data` function.
- ///
- /// Require `Data` to implement `ForeignOwnable`. We guarantee to never move the underlying
- /// wrapped data structure.
- type Data: ForeignOwnable;
+ /// Driver's name.
+ const NAME: &'static CStr;
+
+ /// Driver's flags.
+ const FLAGS: u16;
+
+ /// Boost support.
+ const BOOST_ENABLED: bool;
/// Policy specific data.
///
@@ -804,8 +805,8 @@ fn register_em(_policy: &mut Policy) {
///
/// ```
/// use kernel::{
-/// c_str,
/// cpu, cpufreq,
+/// c_str,
/// device::Device,
/// macros::vtable,
/// sync::Arc,
@@ -817,7 +818,10 @@ fn register_em(_policy: &mut Policy) {
///
/// #[vtable]
/// impl cpufreq::Driver for FooDriver {
-/// type Data = ();
+/// const NAME: &'static CStr = c_str!("cpufreq-foo");
+/// const FLAGS: u16 = cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV;
+/// const BOOST_ENABLED: bool = true;
+///
/// type PData = Arc<FooDevice>;
///
/// fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
@@ -848,13 +852,7 @@ fn register_em(_policy: &mut Policy) {
/// }
///
/// fn foo_probe(dev: &Device) {
-/// cpufreq::Registration::<FooDriver>::new_foreign_owned(
-/// dev,
-/// c_str!("cpufreq-foo"),
-/// (),
-/// cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
-/// true,
-/// ).unwrap();
+/// cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
/// }
/// ```
pub struct Registration<T: Driver> {
@@ -868,13 +866,12 @@ unsafe impl<T: Driver> Sync for Registration<T> {}
#[allow(clippy::non_send_fields_in_send_ty)]
// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any
-// thread. Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is
-// okay to move `Registration` to different threads.
+// thread.
unsafe impl<T: Driver> Send for Registration<T> {}
impl<T: Driver> Registration<T> {
/// Registers a CPU frequency driver with the cpufreq core.
- pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
+ pub fn new() -> Result<Self> {
// Required due to Rust 1.82's stricter handling of `unsafe` in mutable statics. The
// `unsafe` blocks aren't required anymore with later versions.
#![allow(unused_unsafe)]
@@ -886,18 +883,18 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
let drv_ref = drv.get_mut();
// Account for the trailing null byte.
- let len = name.len() + 1;
+ let len = T::NAME.len() + 1;
if len > drv_ref.name.len() {
return Err(EINVAL);
};
- // SAFETY: `name` is a valid `CStr`, and we are copying it to an array of equal or larger
- // size.
- let name = unsafe { &*(name.as_bytes_with_nul() as *const [u8]) };
+ // SAFETY: `T::NAME` is a valid `CStr`, and we are copying it to an array of equal or
+ // larger size.
+ let name = unsafe { &*(T::NAME.as_bytes_with_nul() as *const [u8]) };
drv_ref.name[..len].copy_from_slice(name);
- drv_ref.boost_enabled = boost;
- drv_ref.flags = flags;
+ drv_ref.boost_enabled = T::BOOST_ENABLED;
+ drv_ref.flags = T::FLAGS;
// Initialize mandatory callbacks.
drv_ref.init = Some(Self::init_callback);
@@ -995,10 +992,6 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
None
};
- // Set driver data before registering the driver, as the cpufreq core calls few callbacks
- // before `cpufreq_register_driver` returns.
- Self::set_data(drv_ref, data)?;
-
// SAFETY: It is safe to register the driver with the cpufreq core in the kernel C code.
to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
@@ -1012,53 +1005,10 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
///
/// Instead the [`Registration`] is owned by [`Devres`] and will be revoked / dropped, once the
/// device is detached.
- pub fn new_foreign_owned(
- dev: &Device,
- name: &'static CStr,
- data: T::Data,
- flags: u16,
- boost: bool,
- ) -> Result<()> {
- Devres::new_foreign_owned(dev, Self::new(name, data, flags, boost)?, GFP_KERNEL)?;
+ pub fn new_foreign_owned(dev: &Device) -> Result<()> {
+ Devres::new_foreign_owned(dev, Self::new()?, GFP_KERNEL)?;
Ok(())
}
-
- // Sets the `Data` for the CPU frequency driver.
- fn set_data(drv: &mut bindings::cpufreq_driver, data: T::Data) -> Result<()> {
- if drv.driver_data.is_null() {
- // Transfer the ownership of the data to the C code.
- drv.driver_data = <T::Data as ForeignOwnable>::into_foreign(data) as _;
- Ok(())
- } else {
- Err(EBUSY)
- }
- }
-
- /// Returns borrowed `Data` previously set for the CPU frequency driver.
- pub fn data(&mut self) -> Option<<T::Data as ForeignOwnable>::Borrowed<'static>> {
- let drv = self.drv.get_mut();
-
- if drv.driver_data.is_null() {
- None
- } else {
- // SAFETY: The data is earlier set by us from `set_data`.
- Some(unsafe { <T::Data as ForeignOwnable>::borrow(drv.driver_data) })
- }
- }
-
- // Clears and returns the `Data` for the CPU frequency driver.
- fn clear_data(&mut self) -> Option<T::Data> {
- let drv = self.drv.get_mut();
-
- if drv.driver_data.is_null() {
- None
- } else {
- // SAFETY: The data is earlier set by us from `set_data`.
- let data = Some(unsafe { <T::Data as ForeignOwnable>::from_foreign(drv.driver_data) });
- drv.driver_data = ptr::null_mut();
- data
- }
- }
}
// CPU frequency driver callbacks.
@@ -1313,8 +1263,5 @@ fn drop(&mut self) {
// SAFETY: The driver was earlier registered from `new`.
unsafe { bindings::cpufreq_unregister_driver(drv) };
-
- // Free data
- drop(self.clear_data());
}
}
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-14 8:47 ` Viresh Kumar
@ 2025-04-14 9:39 ` Danilo Krummrich
2025-04-14 10:52 ` Viresh Kumar
0 siblings, 1 reply; 31+ messages in thread
From: Danilo Krummrich @ 2025-04-14 9:39 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Mon, Apr 14, 2025 at 02:17:06PM +0530, Viresh Kumar wrote:
> On 11-04-25, 13:58, Danilo Krummrich wrote:
> > On Fri, Apr 11, 2025 at 04:25:14PM +0530, Viresh Kumar wrote:
>
> > If no, it seems to me that you can even avoid allocating a struct cpufreq_driver
> > dynamically and make it const instead.
>
> I am not sure if I understood your suggestion. The Registration::new()
> method still updates the instance of cpufreq_driver before passing it
> to the C cpufreq core.
See comment in the diff below.
> diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
> index 4194b9558413..9b275d4d3eb6 100644
> --- a/rust/kernel/cpufreq.rs
> +++ b/rust/kernel/cpufreq.rs
> @@ -685,13 +685,14 @@ fn drop(&mut self) {
> /// Reference: <https://docs.kernel.org/cpu-freq/cpu-drivers.html>
> #[vtable]
> pub trait Driver {
> - /// Driver specific data.
> - ///
> - /// Corresponds to the data retrieved via the kernel's `cpufreq_get_driver_data` function.
> - ///
> - /// Require `Data` to implement `ForeignOwnable`. We guarantee to never move the underlying
> - /// wrapped data structure.
> - type Data: ForeignOwnable;
> + /// Driver's name.
> + const NAME: &'static CStr;
> +
> + /// Driver's flags.
> + const FLAGS: u16;
> +
> + /// Boost support.
> + const BOOST_ENABLED: bool;
>
> /// Policy specific data.
> ///
> @@ -804,8 +805,8 @@ fn register_em(_policy: &mut Policy) {
> ///
> /// ```
> /// use kernel::{
> -/// c_str,
> /// cpu, cpufreq,
> +/// c_str,
> /// device::Device,
> /// macros::vtable,
> /// sync::Arc,
> @@ -817,7 +818,10 @@ fn register_em(_policy: &mut Policy) {
> ///
> /// #[vtable]
> /// impl cpufreq::Driver for FooDriver {
> -/// type Data = ();
> +/// const NAME: &'static CStr = c_str!("cpufreq-foo");
> +/// const FLAGS: u16 = cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV;
> +/// const BOOST_ENABLED: bool = true;
> +///
> /// type PData = Arc<FooDevice>;
> ///
> /// fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
> @@ -848,13 +852,7 @@ fn register_em(_policy: &mut Policy) {
> /// }
> ///
> /// fn foo_probe(dev: &Device) {
> -/// cpufreq::Registration::<FooDriver>::new_foreign_owned(
> -/// dev,
> -/// c_str!("cpufreq-foo"),
> -/// (),
> -/// cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
> -/// true,
> -/// ).unwrap();
> +/// cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
> /// }
> /// ```
> pub struct Registration<T: Driver> {
You could define Registration<T: Driver> as
pub struct Registration<T: Driver>(
NonNull<bindings::cpufreq_driver>,
PhantomData<T>
);
and subsequently...
> @@ -868,13 +866,12 @@ unsafe impl<T: Driver> Sync for Registration<T> {}
>
> #[allow(clippy::non_send_fields_in_send_ty)]
> // SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any
> -// thread. Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is
> -// okay to move `Registration` to different threads.
> +// thread.
> unsafe impl<T: Driver> Send for Registration<T> {}
>
> impl<T: Driver> Registration<T> {
...add a new const of type bindings::cpufreq_driver, i.e.
const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver {
name: Self::copy_name(T::NAME),
boost_enabled: T::BOOST_ENABLED,
flags: T::FLAGS,
[...]
}
const fn copy_name(name: &'static CStr) -> [kernel::ffi::c_char; CPUFREQ_NAME_LEN] {
let src name.as_bytes_with_nul();
let mut dst = [0; CPUFREQ_NAME_LEN];
build_assert!(name.len() <= dst.len());
let mut i = 0;
while i < dst.len() {
dst[i] = src[i];
i += 1;
}
dst
}
You should then be able to store a pointer of Self::VTABLE in your Registration
and and hence avoid dynamic allocation of struct cpufreq_driver.
> /// Registers a CPU frequency driver with the cpufreq core.
> - pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
> + pub fn new() -> Result<Self> {
> // Required due to Rust 1.82's stricter handling of `unsafe` in mutable statics. The
> // `unsafe` blocks aren't required anymore with later versions.
> #![allow(unused_unsafe)]
> @@ -886,18 +883,18 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
> let drv_ref = drv.get_mut();
>
> // Account for the trailing null byte.
> - let len = name.len() + 1;
> + let len = T::NAME.len() + 1;
> if len > drv_ref.name.len() {
> return Err(EINVAL);
> };
>
> - // SAFETY: `name` is a valid `CStr`, and we are copying it to an array of equal or larger
> - // size.
> - let name = unsafe { &*(name.as_bytes_with_nul() as *const [u8]) };
> + // SAFETY: `T::NAME` is a valid `CStr`, and we are copying it to an array of equal or
> + // larger size.
> + let name = unsafe { &*(T::NAME.as_bytes_with_nul() as *const [u8]) };
> drv_ref.name[..len].copy_from_slice(name);
>
> - drv_ref.boost_enabled = boost;
> - drv_ref.flags = flags;
> + drv_ref.boost_enabled = T::BOOST_ENABLED;
> + drv_ref.flags = T::FLAGS;
>
> // Initialize mandatory callbacks.
> drv_ref.init = Some(Self::init_callback);
> @@ -995,10 +992,6 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
> None
> };
>
> - // Set driver data before registering the driver, as the cpufreq core calls few callbacks
> - // before `cpufreq_register_driver` returns.
> - Self::set_data(drv_ref, data)?;
> -
> // SAFETY: It is safe to register the driver with the cpufreq core in the kernel C code.
> to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
>
> @@ -1012,53 +1005,10 @@ pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Resul
> ///
> /// Instead the [`Registration`] is owned by [`Devres`] and will be revoked / dropped, once the
> /// device is detached.
> - pub fn new_foreign_owned(
> - dev: &Device,
> - name: &'static CStr,
> - data: T::Data,
> - flags: u16,
> - boost: bool,
> - ) -> Result<()> {
> - Devres::new_foreign_owned(dev, Self::new(name, data, flags, boost)?, GFP_KERNEL)?;
> + pub fn new_foreign_owned(dev: &Device) -> Result<()> {
> + Devres::new_foreign_owned(dev, Self::new()?, GFP_KERNEL)?;
> Ok(())
> }
> -
> - // Sets the `Data` for the CPU frequency driver.
> - fn set_data(drv: &mut bindings::cpufreq_driver, data: T::Data) -> Result<()> {
> - if drv.driver_data.is_null() {
> - // Transfer the ownership of the data to the C code.
> - drv.driver_data = <T::Data as ForeignOwnable>::into_foreign(data) as _;
> - Ok(())
> - } else {
> - Err(EBUSY)
> - }
> - }
> -
> - /// Returns borrowed `Data` previously set for the CPU frequency driver.
> - pub fn data(&mut self) -> Option<<T::Data as ForeignOwnable>::Borrowed<'static>> {
> - let drv = self.drv.get_mut();
> -
> - if drv.driver_data.is_null() {
> - None
> - } else {
> - // SAFETY: The data is earlier set by us from `set_data`.
> - Some(unsafe { <T::Data as ForeignOwnable>::borrow(drv.driver_data) })
> - }
> - }
> -
> - // Clears and returns the `Data` for the CPU frequency driver.
> - fn clear_data(&mut self) -> Option<T::Data> {
> - let drv = self.drv.get_mut();
> -
> - if drv.driver_data.is_null() {
> - None
> - } else {
> - // SAFETY: The data is earlier set by us from `set_data`.
> - let data = Some(unsafe { <T::Data as ForeignOwnable>::from_foreign(drv.driver_data) });
> - drv.driver_data = ptr::null_mut();
> - data
> - }
> - }
> }
>
> // CPU frequency driver callbacks.
> @@ -1313,8 +1263,5 @@ fn drop(&mut self) {
>
> // SAFETY: The driver was earlier registered from `new`.
> unsafe { bindings::cpufreq_unregister_driver(drv) };
> -
> - // Free data
> - drop(self.clear_data());
> }
> }
^ permalink raw reply [flat|nested] 31+ messages in thread* Re: [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-14 9:39 ` Danilo Krummrich
@ 2025-04-14 10:52 ` Viresh Kumar
2025-04-14 11:51 ` Danilo Krummrich
0 siblings, 1 reply; 31+ messages in thread
From: Viresh Kumar @ 2025-04-14 10:52 UTC (permalink / raw)
To: Danilo Krummrich
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On 14-04-25, 11:39, Danilo Krummrich wrote:
> const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver {
> name: Self::copy_name(T::NAME),
> boost_enabled: T::BOOST_ENABLED,
> flags: T::FLAGS,
> [...]
> }
Ahh, thanks for this.
--
viresh
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 9b275d4d3eb6..a6e660d46304 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -9,28 +9,32 @@
//! Reference: <https://docs.kernel.org/admin-guide/pm/cpufreq.html>
use crate::{
+ alloc::AllocError,
bindings,
clk::{Clk, Hertz},
cpumask,
device::Device,
devres::Devres,
error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
- ffi::c_ulong,
+ ffi::{c_char, c_ulong},
prelude::*,
types::ForeignOwnable,
types::Opaque,
};
use core::{
- cell::UnsafeCell,
marker::PhantomData,
+ mem::MaybeUninit,
ops::{Deref, DerefMut},
pin::Pin,
- ptr,
+ ptr::{self, NonNull},
};
use macros::vtable;
+// Maximum length of CPU frequency driver's name.
+const CPUFREQ_NAME_LEN: usize = bindings::CPUFREQ_NAME_LEN as usize;
+
/// Default transition latency value in nanoseconds.
pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32;
@@ -855,10 +859,8 @@ fn register_em(_policy: &mut Policy) {
/// cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
/// }
/// ```
-pub struct Registration<T: Driver> {
- drv: KBox<UnsafeCell<bindings::cpufreq_driver>>,
- _p: PhantomData<T>,
-}
+#[repr(transparent)]
+pub struct Registration<T: Driver>(NonNull<bindings::cpufreq_driver>, PhantomData<T>);
// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
// or CPUs, so it is safe to share it.
@@ -870,135 +872,136 @@ unsafe impl<T: Driver> Sync for Registration<T> {}
unsafe impl<T: Driver> Send for Registration<T> {}
impl<T: Driver> Registration<T> {
- /// Registers a CPU frequency driver with the cpufreq core.
- pub fn new() -> Result<Self> {
- // Required due to Rust 1.82's stricter handling of `unsafe` in mutable statics. The
- // `unsafe` blocks aren't required anymore with later versions.
- #![allow(unused_unsafe)]
-
- let mut drv = KBox::new(
- UnsafeCell::new(bindings::cpufreq_driver::default()),
- GFP_KERNEL,
- )?;
- let drv_ref = drv.get_mut();
-
- // Account for the trailing null byte.
- let len = T::NAME.len() + 1;
- if len > drv_ref.name.len() {
- return Err(EINVAL);
- };
-
- // SAFETY: `T::NAME` is a valid `CStr`, and we are copying it to an array of equal or
- // larger size.
- let name = unsafe { &*(T::NAME.as_bytes_with_nul() as *const [u8]) };
- drv_ref.name[..len].copy_from_slice(name);
-
- drv_ref.boost_enabled = T::BOOST_ENABLED;
- drv_ref.flags = T::FLAGS;
+ const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver {
+ name: Self::copy_name(T::NAME),
+ boost_enabled: T::BOOST_ENABLED,
+ flags: T::FLAGS,
// Initialize mandatory callbacks.
- drv_ref.init = Some(Self::init_callback);
- drv_ref.verify = Some(Self::verify_callback);
+ init: Some(Self::init_callback),
+ verify: Some(Self::verify_callback),
// Initialize optional callbacks based on the traits of `T`.
- drv_ref.setpolicy = if T::HAS_SETPOLICY {
+ setpolicy: if T::HAS_SETPOLICY {
Some(Self::setpolicy_callback)
} else {
None
- };
- drv_ref.target = if T::HAS_TARGET {
+ },
+ target: if T::HAS_TARGET {
Some(Self::target_callback)
} else {
None
- };
- drv_ref.target_index = if T::HAS_TARGET_INDEX {
+ },
+ target_index: if T::HAS_TARGET_INDEX {
Some(Self::target_index_callback)
} else {
None
- };
- drv_ref.fast_switch = if T::HAS_FAST_SWITCH {
+ },
+ fast_switch: if T::HAS_FAST_SWITCH {
Some(Self::fast_switch_callback)
} else {
None
- };
- drv_ref.adjust_perf = if T::HAS_ADJUST_PERF {
+ },
+ adjust_perf: if T::HAS_ADJUST_PERF {
Some(Self::adjust_perf_callback)
} else {
None
- };
- drv_ref.get_intermediate = if T::HAS_GET_INTERMEDIATE {
+ },
+ get_intermediate: if T::HAS_GET_INTERMEDIATE {
Some(Self::get_intermediate_callback)
} else {
None
- };
- drv_ref.target_intermediate = if T::HAS_TARGET_INTERMEDIATE {
+ },
+ target_intermediate: if T::HAS_TARGET_INTERMEDIATE {
Some(Self::target_intermediate_callback)
} else {
None
- };
- drv_ref.get = if T::HAS_GET {
+ },
+ get: if T::HAS_GET {
Some(Self::get_callback)
} else {
None
- };
- drv_ref.update_limits = if T::HAS_UPDATE_LIMITS {
+ },
+ update_limits: if T::HAS_UPDATE_LIMITS {
Some(Self::update_limits_callback)
} else {
None
- };
- drv_ref.bios_limit = if T::HAS_BIOS_LIMIT {
+ },
+ bios_limit: if T::HAS_BIOS_LIMIT {
Some(Self::bios_limit_callback)
} else {
None
- };
- drv_ref.online = if T::HAS_ONLINE {
+ },
+ online: if T::HAS_ONLINE {
Some(Self::online_callback)
} else {
None
- };
- drv_ref.offline = if T::HAS_OFFLINE {
+ },
+ offline: if T::HAS_OFFLINE {
Some(Self::offline_callback)
} else {
None
- };
- drv_ref.exit = if T::HAS_EXIT {
+ },
+ exit: if T::HAS_EXIT {
Some(Self::exit_callback)
} else {
None
- };
- drv_ref.suspend = if T::HAS_SUSPEND {
+ },
+ suspend: if T::HAS_SUSPEND {
Some(Self::suspend_callback)
} else {
None
- };
- drv_ref.resume = if T::HAS_RESUME {
+ },
+ resume: if T::HAS_RESUME {
Some(Self::resume_callback)
} else {
None
- };
- drv_ref.ready = if T::HAS_READY {
+ },
+ ready: if T::HAS_READY {
Some(Self::ready_callback)
} else {
None
- };
- drv_ref.set_boost = if T::HAS_SET_BOOST {
+ },
+ set_boost: if T::HAS_SET_BOOST {
Some(Self::set_boost_callback)
} else {
None
- };
- drv_ref.register_em = if T::HAS_REGISTER_EM {
+ },
+ register_em: if T::HAS_REGISTER_EM {
Some(Self::register_em_callback)
} else {
None
- };
+ },
+ // SAFETY: All zeros is a valid value for `bindings::cpufreq_driver`.
+ ..unsafe { MaybeUninit::zeroed().assume_init() }
+ };
+
+ const fn copy_name(name: &'static CStr) -> [c_char; CPUFREQ_NAME_LEN] {
+ let src = name.as_bytes_with_nul();
+ let mut dst = [0; CPUFREQ_NAME_LEN];
+
+ build_assert!(src.len() <= CPUFREQ_NAME_LEN);
+
+ let mut i = 0;
+ while i < src.len() {
+ dst[i] = src[i];
+ i += 1;
+ }
+
+ dst
+ }
+
+ /// Registers a CPU frequency driver with the cpufreq core.
+ pub fn new() -> Result<Self> {
+ let drv = &Self::VTABLE as *const _ as *mut _;
// SAFETY: It is safe to register the driver with the cpufreq core in the kernel C code.
- to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
+ to_result(unsafe { bindings::cpufreq_register_driver(drv) })?;
- Ok(Self {
- drv,
- _p: PhantomData,
- })
+ Ok(Self(
+ NonNull::new(drv.cast()).ok_or(AllocError)?,
+ PhantomData,
+ ))
}
/// Same as [`Registration::new`], but does not return a [`Registration`] instance.
@@ -1259,9 +1262,7 @@ extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) {
impl<T: Driver> Drop for Registration<T> {
// Removes the `Registration` from the kernel, if it has initialized successfully earlier.
fn drop(&mut self) {
- let drv = self.drv.get_mut();
-
// SAFETY: The driver was earlier registered from `new`.
- unsafe { bindings::cpufreq_unregister_driver(drv) };
+ unsafe { bindings::cpufreq_unregister_driver(self.0.as_ptr()) };
}
}
^ permalink raw reply related [flat|nested] 31+ messages in thread* Re: [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration
2025-04-14 10:52 ` Viresh Kumar
@ 2025-04-14 11:51 ` Danilo Krummrich
0 siblings, 0 replies; 31+ messages in thread
From: Danilo Krummrich @ 2025-04-14 11:51 UTC (permalink / raw)
To: Viresh Kumar
Cc: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Miguel Ojeda,
Alex Gaynor, Boqun Feng, Gary Guo, Björn Roy Baron,
Benno Lossin, Andreas Hindborg, Alice Ryhl, Trevor Gross,
linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
On Mon, Apr 14, 2025 at 04:22:12PM +0530, Viresh Kumar wrote:
> On 14-04-25, 11:39, Danilo Krummrich wrote:
> > const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver {
> > name: Self::copy_name(T::NAME),
> > boost_enabled: T::BOOST_ENABLED,
> > flags: T::FLAGS,
> > [...]
> > }
>
> Ahh, thanks for this.
The diff below looks good!
One nit below.
> diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
> index 9b275d4d3eb6..a6e660d46304 100644
> --- a/rust/kernel/cpufreq.rs
> +++ b/rust/kernel/cpufreq.rs
> @@ -9,28 +9,32 @@
> //! Reference: <https://docs.kernel.org/admin-guide/pm/cpufreq.html>
>
> use crate::{
> + alloc::AllocError,
> bindings,
> clk::{Clk, Hertz},
> cpumask,
> device::Device,
> devres::Devres,
> error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
> - ffi::c_ulong,
> + ffi::{c_char, c_ulong},
> prelude::*,
> types::ForeignOwnable,
> types::Opaque,
> };
>
> use core::{
> - cell::UnsafeCell,
> marker::PhantomData,
> + mem::MaybeUninit,
> ops::{Deref, DerefMut},
> pin::Pin,
> - ptr,
> + ptr::{self, NonNull},
> };
>
> use macros::vtable;
>
> +// Maximum length of CPU frequency driver's name.
> +const CPUFREQ_NAME_LEN: usize = bindings::CPUFREQ_NAME_LEN as usize;
> +
> /// Default transition latency value in nanoseconds.
> pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32;
>
> @@ -855,10 +859,8 @@ fn register_em(_policy: &mut Policy) {
> /// cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
> /// }
> /// ```
> -pub struct Registration<T: Driver> {
> - drv: KBox<UnsafeCell<bindings::cpufreq_driver>>,
> - _p: PhantomData<T>,
> -}
> +#[repr(transparent)]
> +pub struct Registration<T: Driver>(NonNull<bindings::cpufreq_driver>, PhantomData<T>);
>
> // SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
> // or CPUs, so it is safe to share it.
> @@ -870,135 +872,136 @@ unsafe impl<T: Driver> Sync for Registration<T> {}
> unsafe impl<T: Driver> Send for Registration<T> {}
>
> impl<T: Driver> Registration<T> {
> - /// Registers a CPU frequency driver with the cpufreq core.
> - pub fn new() -> Result<Self> {
> - // Required due to Rust 1.82's stricter handling of `unsafe` in mutable statics. The
> - // `unsafe` blocks aren't required anymore with later versions.
> - #![allow(unused_unsafe)]
> -
> - let mut drv = KBox::new(
> - UnsafeCell::new(bindings::cpufreq_driver::default()),
> - GFP_KERNEL,
> - )?;
> - let drv_ref = drv.get_mut();
> -
> - // Account for the trailing null byte.
> - let len = T::NAME.len() + 1;
> - if len > drv_ref.name.len() {
> - return Err(EINVAL);
> - };
> -
> - // SAFETY: `T::NAME` is a valid `CStr`, and we are copying it to an array of equal or
> - // larger size.
> - let name = unsafe { &*(T::NAME.as_bytes_with_nul() as *const [u8]) };
> - drv_ref.name[..len].copy_from_slice(name);
> -
> - drv_ref.boost_enabled = T::BOOST_ENABLED;
> - drv_ref.flags = T::FLAGS;
> + const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver {
> + name: Self::copy_name(T::NAME),
> + boost_enabled: T::BOOST_ENABLED,
> + flags: T::FLAGS,
>
> // Initialize mandatory callbacks.
> - drv_ref.init = Some(Self::init_callback);
> - drv_ref.verify = Some(Self::verify_callback);
> + init: Some(Self::init_callback),
> + verify: Some(Self::verify_callback),
>
> // Initialize optional callbacks based on the traits of `T`.
> - drv_ref.setpolicy = if T::HAS_SETPOLICY {
> + setpolicy: if T::HAS_SETPOLICY {
> Some(Self::setpolicy_callback)
> } else {
> None
> - };
> - drv_ref.target = if T::HAS_TARGET {
> + },
> + target: if T::HAS_TARGET {
> Some(Self::target_callback)
> } else {
> None
> - };
> - drv_ref.target_index = if T::HAS_TARGET_INDEX {
> + },
> + target_index: if T::HAS_TARGET_INDEX {
> Some(Self::target_index_callback)
> } else {
> None
> - };
> - drv_ref.fast_switch = if T::HAS_FAST_SWITCH {
> + },
> + fast_switch: if T::HAS_FAST_SWITCH {
> Some(Self::fast_switch_callback)
> } else {
> None
> - };
> - drv_ref.adjust_perf = if T::HAS_ADJUST_PERF {
> + },
> + adjust_perf: if T::HAS_ADJUST_PERF {
> Some(Self::adjust_perf_callback)
> } else {
> None
> - };
> - drv_ref.get_intermediate = if T::HAS_GET_INTERMEDIATE {
> + },
> + get_intermediate: if T::HAS_GET_INTERMEDIATE {
> Some(Self::get_intermediate_callback)
> } else {
> None
> - };
> - drv_ref.target_intermediate = if T::HAS_TARGET_INTERMEDIATE {
> + },
> + target_intermediate: if T::HAS_TARGET_INTERMEDIATE {
> Some(Self::target_intermediate_callback)
> } else {
> None
> - };
> - drv_ref.get = if T::HAS_GET {
> + },
> + get: if T::HAS_GET {
> Some(Self::get_callback)
> } else {
> None
> - };
> - drv_ref.update_limits = if T::HAS_UPDATE_LIMITS {
> + },
> + update_limits: if T::HAS_UPDATE_LIMITS {
> Some(Self::update_limits_callback)
> } else {
> None
> - };
> - drv_ref.bios_limit = if T::HAS_BIOS_LIMIT {
> + },
> + bios_limit: if T::HAS_BIOS_LIMIT {
> Some(Self::bios_limit_callback)
> } else {
> None
> - };
> - drv_ref.online = if T::HAS_ONLINE {
> + },
> + online: if T::HAS_ONLINE {
> Some(Self::online_callback)
> } else {
> None
> - };
> - drv_ref.offline = if T::HAS_OFFLINE {
> + },
> + offline: if T::HAS_OFFLINE {
> Some(Self::offline_callback)
> } else {
> None
> - };
> - drv_ref.exit = if T::HAS_EXIT {
> + },
> + exit: if T::HAS_EXIT {
> Some(Self::exit_callback)
> } else {
> None
> - };
> - drv_ref.suspend = if T::HAS_SUSPEND {
> + },
> + suspend: if T::HAS_SUSPEND {
> Some(Self::suspend_callback)
> } else {
> None
> - };
> - drv_ref.resume = if T::HAS_RESUME {
> + },
> + resume: if T::HAS_RESUME {
> Some(Self::resume_callback)
> } else {
> None
> - };
> - drv_ref.ready = if T::HAS_READY {
> + },
> + ready: if T::HAS_READY {
> Some(Self::ready_callback)
> } else {
> None
> - };
> - drv_ref.set_boost = if T::HAS_SET_BOOST {
> + },
> + set_boost: if T::HAS_SET_BOOST {
> Some(Self::set_boost_callback)
> } else {
> None
> - };
> - drv_ref.register_em = if T::HAS_REGISTER_EM {
> + },
> + register_em: if T::HAS_REGISTER_EM {
> Some(Self::register_em_callback)
> } else {
> None
> - };
> + },
> + // SAFETY: All zeros is a valid value for `bindings::cpufreq_driver`.
> + ..unsafe { MaybeUninit::zeroed().assume_init() }
> + };
> +
> + const fn copy_name(name: &'static CStr) -> [c_char; CPUFREQ_NAME_LEN] {
> + let src = name.as_bytes_with_nul();
> + let mut dst = [0; CPUFREQ_NAME_LEN];
> +
> + build_assert!(src.len() <= CPUFREQ_NAME_LEN);
> +
> + let mut i = 0;
> + while i < src.len() {
> + dst[i] = src[i];
> + i += 1;
> + }
> +
> + dst
> + }
> +
> + /// Registers a CPU frequency driver with the cpufreq core.
> + pub fn new() -> Result<Self> {
> + let drv = &Self::VTABLE as *const _ as *mut _;
Hm, I didn't think of that, maybe it's better to store a *const directly instead
of a NonNull, given that VTABLE can't be altered.
Tamir is trying to clean up 'as' casts in [1]. So, I'd write this as
let drv: *const bindings::cpufreq_driver = &Self::VTABLE;
[1] https://lore.kernel.org/rust-for-linux/20250409-ptr-as-ptr-v8-0-3738061534ef@gmail.com/
>
> // SAFETY: It is safe to register the driver with the cpufreq core in the kernel C code.
> - to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
> + to_result(unsafe { bindings::cpufreq_register_driver(drv) })?;
>
> - Ok(Self {
> - drv,
> - _p: PhantomData,
> - })
> + Ok(Self(
> + NonNull::new(drv.cast()).ok_or(AllocError)?,
> + PhantomData,
> + ))
> }
>
> /// Same as [`Registration::new`], but does not return a [`Registration`] instance.
> @@ -1259,9 +1262,7 @@ extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) {
> impl<T: Driver> Drop for Registration<T> {
> // Removes the `Registration` from the kernel, if it has initialized successfully earlier.
> fn drop(&mut self) {
> - let drv = self.drv.get_mut();
> -
> // SAFETY: The driver was earlier registered from `new`.
> - unsafe { bindings::cpufreq_unregister_driver(drv) };
> + unsafe { bindings::cpufreq_unregister_driver(self.0.as_ptr()) };
> }
> }
^ permalink raw reply [flat|nested] 31+ messages in thread
* [PATCH V9 16/17] rust: opp: Extend OPP abstractions with cpufreq support
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (14 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 15/17] rust: cpufreq: Extend abstractions for driver registration Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
2025-04-11 10:55 ` [PATCH V9 17/17] cpufreq: Add Rust-based cpufreq-dt driver Viresh Kumar
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Nishanth Menon, Stephen Boyd, Miguel Ojeda, Alex Gaynor,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Danilo Krummrich
Cc: Viresh Kumar, linux-pm, Vincent Guittot, rust-for-linux,
Manos Pitsidianakis, Erik Schilling, Alex Bennée,
Joakim Bech, Rob Herring, Yury Norov, Burak Emir,
Rasmus Villemoes, Russell King, linux-clk, Michael Turquette,
linux-kernel
Extend the OPP abstractions to include support for interacting with the
cpufreq core, including the ability to retrieve frequency tables from
OPP table.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
rust/kernel/opp.rs | 67 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 7bf612fa0cc5..a46ac28d4464 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -20,6 +20,12 @@
types::{ARef, AlwaysRefCounted, Opaque},
};
+#[cfg(CONFIG_CPU_FREQ)]
+use crate::cpufreq;
+
+#[cfg(CONFIG_CPU_FREQ)]
+use core::ops::Deref;
+
use core::{marker::PhantomData, ptr};
use macros::vtable;
@@ -497,6 +503,60 @@ extern "C" fn config_regulators(
}
}
+/// OPP frequency table.
+///
+/// A [`cpufreq::Table`] created from [`Table`].
+#[cfg(CONFIG_CPU_FREQ)]
+pub struct FreqTable {
+ dev: ARef<Device>,
+ ptr: *mut bindings::cpufreq_frequency_table,
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl FreqTable {
+ /// Creates a new instance of [`FreqTable`] from [`Table`].
+ fn new(table: &Table) -> Result<Self> {
+ let mut ptr: *mut bindings::cpufreq_frequency_table = ptr::null_mut();
+
+ // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
+ // requirements.
+ to_result(unsafe {
+ bindings::dev_pm_opp_init_cpufreq_table(table.dev.as_raw(), &mut ptr)
+ })?;
+
+ Ok(Self {
+ dev: table.dev.clone(),
+ ptr,
+ })
+ }
+
+ // Returns a reference to the underlying [`cpufreq::Table`].
+ #[inline]
+ fn table(&self) -> &cpufreq::Table {
+ // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+ unsafe { cpufreq::Table::from_raw(self.ptr) }
+ }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl Deref for FreqTable {
+ type Target = cpufreq::Table;
+
+ #[inline]
+ fn deref(&self) -> &Self::Target {
+ self.table()
+ }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl Drop for FreqTable {
+ fn drop(&mut self) {
+ // SAFETY: The pointer was created via `dev_pm_opp_init_cpufreq_table`, and is only freed
+ // here.
+ unsafe { bindings::dev_pm_opp_free_cpufreq_table(self.dev.as_raw(), &mut self.as_raw()) };
+ }
+}
+
/// A reference-counted OPP table.
///
/// Rust abstraction for the C `struct opp_table`.
@@ -752,6 +812,13 @@ pub fn adjust_voltage(
})
}
+ /// Creates [`FreqTable`] from [`Table`].
+ #[cfg(CONFIG_CPU_FREQ)]
+ #[inline]
+ pub fn cpufreq_table(&mut self) -> Result<FreqTable> {
+ FreqTable::new(self)
+ }
+
/// Configures device with [`OPP`] matching the frequency value.
#[inline]
pub fn set_rate(&self, freq: Hertz) -> Result<()> {
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread* [PATCH V9 17/17] cpufreq: Add Rust-based cpufreq-dt driver
2025-04-11 10:54 [PATCH V9 00/17] Rust abstractions for clk, cpumask, cpufreq, OPP Viresh Kumar
` (15 preceding siblings ...)
2025-04-11 10:55 ` [PATCH V9 16/17] rust: opp: Extend OPP abstractions with cpufreq support Viresh Kumar
@ 2025-04-11 10:55 ` Viresh Kumar
16 siblings, 0 replies; 31+ messages in thread
From: Viresh Kumar @ 2025-04-11 10:55 UTC (permalink / raw)
To: Rafael J. Wysocki, Miguel Ojeda, Danilo Krummrich, Viresh Kumar,
Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Danilo Krummrich
Cc: linux-pm, Vincent Guittot, Stephen Boyd, Nishanth Menon,
rust-for-linux, Manos Pitsidianakis, Erik Schilling,
Alex Bennée, Joakim Bech, Rob Herring, Yury Norov,
Burak Emir, Rasmus Villemoes, Russell King, linux-clk,
Michael Turquette, linux-kernel
Introduce a Rust-based implementation of the cpufreq-dt driver, covering
most of the functionality provided by the existing C version. Some
features, such as retrieving platform data from `cpufreq-dt-platdev.c`,
are still pending.
The driver has been tested with QEMU, and frequency scaling works as
expected.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/cpufreq/Kconfig | 12 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/rcpufreq_dt.rs | 236 +++++++++++++++++++++++++++++++++
3 files changed, 249 insertions(+)
create mode 100644 drivers/cpufreq/rcpufreq_dt.rs
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index d64b07ec48e5..78702a08364f 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -217,6 +217,18 @@ config CPUFREQ_DT
If in doubt, say N.
+config CPUFREQ_DT_RUST
+ tristate "Rust based Generic DT based cpufreq driver"
+ depends on HAVE_CLK && OF && RUST
+ select CPUFREQ_DT_PLATDEV
+ select PM_OPP
+ help
+ This adds a Rust based generic DT based cpufreq driver for frequency
+ management. It supports both uniprocessor (UP) and symmetric
+ multiprocessor (SMP) systems.
+
+ If in doubt, say N.
+
config CPUFREQ_VIRT
tristate "Virtual cpufreq driver"
depends on GENERIC_ARCH_TOPOLOGY
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 22ab45209f9b..d38526b8e063 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_COMMON) += cpufreq_governor.o
obj-$(CONFIG_CPU_FREQ_GOV_ATTR_SET) += cpufreq_governor_attr_set.o
obj-$(CONFIG_CPUFREQ_DT) += cpufreq-dt.o
+obj-$(CONFIG_CPUFREQ_DT_RUST) += rcpufreq_dt.o
obj-$(CONFIG_CPUFREQ_DT_PLATDEV) += cpufreq-dt-platdev.o
obj-$(CONFIG_CPUFREQ_VIRT) += virtual-cpufreq.o
diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
new file mode 100644
index 000000000000..751be33c0218
--- /dev/null
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust based implementation of the cpufreq-dt driver.
+
+use kernel::{
+ c_str,
+ clk::Clk,
+ cpu, cpufreq,
+ cpumask::CpumaskVar,
+ device::{Core, Device},
+ error::code::*,
+ fmt,
+ macros::vtable,
+ module_platform_driver, of, opp, platform,
+ prelude::*,
+ str::CString,
+ sync::Arc,
+};
+
+// Finds exact supply name from the OF node.
+fn find_supply_name_exact(dev: &Device, name: &str) -> Option<CString> {
+ let prop_name = CString::try_from_fmt(fmt!("{}-supply", name)).ok()?;
+ dev.property_present(&prop_name)
+ .then(|| CString::try_from_fmt(fmt!("{name}")).ok())
+ .flatten()
+}
+
+// Finds supply name for the CPU from DT.
+fn find_supply_names(dev: &Device, cpu: u32) -> Option<KVec<CString>> {
+ // Try "cpu0" for older DTs, fallback to "cpu".
+ let name = (cpu == 0)
+ .then(|| find_supply_name_exact(dev, "cpu0"))
+ .flatten()
+ .or_else(|| find_supply_name_exact(dev, "cpu"))?;
+
+ let mut list = KVec::with_capacity(1, GFP_KERNEL).ok()?;
+ list.push(name, GFP_KERNEL).ok()?;
+
+ Some(list)
+}
+
+// Represents the cpufreq dt device.
+struct CPUFreqDTDevice {
+ opp_table: opp::Table,
+ freq_table: opp::FreqTable,
+ #[allow(dead_code)]
+ mask: CpumaskVar,
+ #[allow(dead_code)]
+ token: Option<opp::ConfigToken>,
+ #[allow(dead_code)]
+ clk: Clk,
+}
+
+#[derive(Default)]
+struct CPUFreqDTDriver;
+
+#[vtable]
+impl opp::ConfigOps for CPUFreqDTDriver {}
+
+#[vtable]
+impl cpufreq::Driver for CPUFreqDTDriver {
+ type Data = ();
+ type PData = Arc<CPUFreqDTDevice>;
+
+ fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
+ let cpu = policy.cpu();
+ // SAFETY: The CPU device is only used during init; it won't get hot-unplugged. The cpufreq
+ // core registers with CPU notifiers and the cpufreq core/driver won't use the CPU device,
+ // once the CPU is hot-unplugged.
+ let dev = unsafe { cpu::from_cpu(cpu)? };
+ let mut mask = CpumaskVar::new(GFP_KERNEL)?;
+
+ mask.set(cpu);
+
+ let token = find_supply_names(dev, cpu)
+ .map(|names| {
+ opp::Config::<Self>::new()
+ .set_regulator_names(names)?
+ .set(dev)
+ })
+ .transpose()?;
+
+ // Get OPP-sharing information from "operating-points-v2" bindings.
+ let fallback = match opp::Table::of_sharing_cpus(dev, &mut mask) {
+ Ok(()) => false,
+ Err(e) if e == ENOENT => {
+ // "operating-points-v2" not supported. If the platform hasn't
+ // set sharing CPUs, fallback to all CPUs share the `Policy`
+ // for backward compatibility.
+ opp::Table::sharing_cpus(dev, &mut mask).is_err()
+ }
+ Err(e) => return Err(e),
+ };
+
+ // Initialize OPP tables for all policy cpus.
+ //
+ // For platforms not using "operating-points-v2" bindings, we do this
+ // before updating policy cpus. Otherwise, we will end up creating
+ // duplicate OPPs for the CPUs.
+ //
+ // OPPs might be populated at runtime, don't fail for error here unless
+ // it is -EPROBE_DEFER.
+ let mut opp_table = match opp::Table::from_of_cpumask(dev, &mut mask) {
+ Ok(table) => table,
+ Err(e) => {
+ if e == EPROBE_DEFER {
+ return Err(e);
+ }
+
+ // The table is added dynamically ?
+ opp::Table::from_dev(dev)?
+ }
+ };
+
+ // The OPP table must be initialized, statically or dynamically, by this point.
+ opp_table.opp_count()?;
+
+ // Set sharing cpus for fallback scenario.
+ if fallback {
+ mask.setall();
+ opp_table.set_sharing_cpus(&mut mask)?;
+ }
+
+ let mut transition_latency = opp_table.max_transition_latency_ns() as u32;
+ if transition_latency == 0 {
+ transition_latency = cpufreq::ETERNAL_LATENCY_NS;
+ }
+
+ policy
+ .set_dvfs_possible_from_any_cpu(true)
+ .set_suspend_freq(opp_table.suspend_freq())
+ .set_transition_latency_ns(transition_latency);
+
+ let freq_table = opp_table.cpufreq_table()?;
+ // SAFETY: The `freq_table` is not dropped while it is getting used by the C code.
+ unsafe { policy.set_freq_table(&freq_table) };
+
+ // SAFETY: The returned `clk` is not dropped while it is getting used by the C code.
+ let clk = unsafe { policy.set_clk(dev, None)? };
+
+ mask.copy(policy.cpus());
+
+ Ok(Arc::new(
+ CPUFreqDTDevice {
+ opp_table,
+ freq_table,
+ mask,
+ token,
+ clk,
+ },
+ GFP_KERNEL,
+ )?)
+ }
+
+ fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
+ Ok(())
+ }
+
+ fn online(_policy: &mut cpufreq::Policy) -> Result<()> {
+ // We did light-weight tear down earlier, nothing to do here.
+ Ok(())
+ }
+
+ fn offline(_policy: &mut cpufreq::Policy) -> Result<()> {
+ // Preserve policy->data and don't free resources on light-weight
+ // tear down.
+ Ok(())
+ }
+
+ fn suspend(policy: &mut cpufreq::Policy) -> Result<()> {
+ policy.generic_suspend()
+ }
+
+ fn verify(data: &mut cpufreq::PolicyData) -> Result<()> {
+ data.generic_verify()
+ }
+
+ fn target_index(policy: &mut cpufreq::Policy, index: u32) -> Result<()> {
+ let Some(data) = policy.data::<Self::PData>() else {
+ return Err(ENOENT);
+ };
+
+ // SAFETY: `index` is guaranteed to be valid by the C API.
+ let freq = unsafe { data.freq_table.freq(index.try_into()?)? };
+ data.opp_table.set_rate(freq)
+ }
+
+ fn get(policy: &mut cpufreq::Policy) -> Result<u32> {
+ policy.generic_get()
+ }
+
+ fn set_boost(_policy: &mut cpufreq::Policy, _state: i32) -> Result<()> {
+ Ok(())
+ }
+
+ fn register_em(policy: &mut cpufreq::Policy) {
+ policy.register_em_opp()
+ }
+}
+
+kernel::of_device_table!(
+ OF_TABLE,
+ MODULE_OF_TABLE,
+ <CPUFreqDTDriver as platform::Driver>::IdInfo,
+ [(of::DeviceId::new(c_str!("operating-points-v2")), ())]
+);
+
+impl platform::Driver for CPUFreqDTDriver {
+ type IdInfo = ();
+ const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+
+ fn probe(
+ pdev: &platform::Device<Core>,
+ _id_info: Option<&Self::IdInfo>,
+ ) -> Result<Pin<KBox<Self>>> {
+ cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(
+ pdev.as_ref(),
+ c_str!("cpufreq-dt"),
+ (),
+ cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
+ true,
+ )?;
+
+ let drvdata = KBox::new(Self {}, GFP_KERNEL)?;
+
+ Ok(drvdata.into())
+ }
+}
+
+module_platform_driver! {
+ type: CPUFreqDTDriver,
+ name: "cpufreq-dt",
+ author: "Viresh Kumar <viresh.kumar@linaro.org>",
+ description: "Generic CPUFreq DT driver",
+ license: "GPL v2",
+}
--
2.31.1.272.g89b43f80a514
^ permalink raw reply related [flat|nested] 31+ messages in thread