[PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Viresh Kumar]

Hello,

I have queued this up for v6.16-rc1, will merge it via the PM tree soon.
Thanks.

This series introduces initial Rust abstractions for a few subsystems: clk,
cpumask, cpufreq and Operating Performance Points (OPP).

The abstractions cover most of the interfaces exposed by cpufreq and OPP
subsystems. It also includes minimal abstractions for the clk and cpumask
frameworks, which are required by the cpufreq / OPP abstractions.

Additionally, a sample `rcpufreq-dt` driver is included. This is a
duplicate of the existing `cpufreq-dt` driver, which is a
platform-agnostic, device-tree based cpufreq driver commonly used on ARM
platforms.

The implementation has been tested using QEMU, ensuring that frequency
transitions, various configurations, and driver binding/unbinding work as
expected. However, performance measurements have not been conducted yet.

For those interested in testing these patches, they can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git rust/cpufreq-dt

Based on 6.15-rc1 + rust/devres dependencies + PM/cpufreq dependencies.

V11->V12:
- Added tags from Yury.
- Use "'static" for CStr in cpufreq-dt driver.
- Move clk code in a new module "common_clk" to fix build errors in the absence
  of CONFIG_COMMON_CLK (x86 for example).
- Use #[cfg(CONFIG_COMMON_CLK)] at few more places for Clk usage.
- Use Device<Bound>.
- Update prototype of update_limits_callback() (sync with PM tree).

V10->V11:
- cpufreq: Add TableIndex and make table methods safe.
- opp: Add freq module to keep all cfg stuff together.
- Use /// instead of // for documentation comments, even for private
  definitions.
- Switch back to heap allocation for `struct cpufreq_driver` as it needs to be a
  mutable object.
- Remove allow(dead_code)
- Improve few safety comments.
- Danilo: I haven't added your RBY tag to patch 13/15 as there were significant
  changes from the initial version.

V9->V10:
- Don't remove atomic cpumask bindings from rust/helpers/cpumask.c
- Rename from_raw/from_raw_mut to as_ref/as_mut_ref (cpumask).
- Improved comments for non-atomic methods (cpumask).
- s/new/new_zero/ and s/new_uninit/new/ (cpumask).
- Avoid using explicit casts `as *const` or `as *mut`.
- Renamed `cpumask_box` to `cpumask_var` and `cpus`.
- Add local types in Rust for cpufreq flags that use BIT().
- Add const initializer for cpufreq::Registration and simplify new().
- Improved few safety comments.

V8->V9:
- clk (changes since V4):
  - V4: https://lore.kernel.org/all/cover.1742276963.git.viresh.kumar@linaro.org/
  - Add more methods in Hertz (as_khz/mhz/ghz).
  - Reword a comment.

- cpumask (changes since V4):
  - V4: https://lore.kernel.org/all/cover.1743572195.git.viresh.kumar@linaro.org/
  - Add support for cpumask_{test_cpu|empty|full} and switch to using non-atomic
    helpers for set/clear.
  - s/CpumaskBox/CpumaskVar/
  - s/set_all/setall/
  - Improved examples, comments and commit logs.

- cpufreq/opp:
  - V8: https://lore.kernel.org/all/cover.1738832118.git.viresh.kumar@linaro.org/
  - Based on review comments received for clk/cpumask, a lot of changes were
    made to cpufreq/opp bindings in code, comments, examples, etc..
  - `attr` fields were dropped from cpufreq support, not required anymore
    because of latest changes in cpufreq core.
  - Use Hertz/MicroVolt/MicroWatt as units.
  - Lots of other cleanups.
  - Dropped Reviewed-by from Manos (there were too many changes).

V7->V8:
- Updated cpumask bindings to work with !CONFIG_CPUMASK_OFFSTACK case.
- Dropped few patches (property_present() and opp helpers), as they are already
  merged.
- from_cpu() is marked unsafe.
- Included a patch by Anisse Astier, to solve a long standing issue with this
  series.
- Dropped: "DO-NOT_MERGE: cpufreq: Rename cpufreq-dt platdev."
- Updated MAINTAINERS for new files.
- Other minor changes / cleanups.

V6->V7:
- from_cpu() is moved to cpu.rs and doesn't return ARef anymore, but just a
  reference.
- Dropped cpufreq_table_len() and related validation in cpufreq core.
- Solved the issue with BIT() macro differently, using an enum now.
- Few patches are broken into smaller / independent patches.
- Improved Commit logs and SAFETY comments at few places.
- Removed print message from cpufreq driver.
- Rebased over linux-next/master.
- Few other minor changes.

V5->V6:
- Rebase over latest rust/dev branch, which changed few interfaces that the
  patches were using.
- Included all other patches, which weren't included until now to focus only on
  core APIs.
- Other minor cleanups, additions.

V4->V5:
- Rename Registration::register() as new().
- Provide a new API: Registration::new_foreign_owned() and use it for
  rcpufreq_dt driver.
- Update MAINTAINERS file.

V3->V4:
- Fix bugs with freeing of OPP structure. Dropped the Drop routine and fixed
  reference counting.
- Registration object of the cpufreq core is modified a bit to remove the
  registered field, and few other cleanups.
- Use Devres for instead of platform data.
- Improve SAFETY comments.

V2->V3:
- Rebased on latest rust-device changes, which removed `Data` and so few changes
  were required to make it work.
- use srctree links (Alice Ryhl).
- Various changes the OPP creation APIs, new APIs: from_raw_opp() and
  from_raw_opp_owned() (Alice Ryhl).
- Inline as_raw() helpers (Alice Ryhl).
- Add new interface (`OPP::Token`) for dynamically created OPPs.
- Add Reviewed-by tag from Manos.
- Modified/simplified cpufreq registration structure / method a bit.

V1->V2:
- Create and use separate bindings for OF, clk, cpumask, etc (not included in
  this patchset but pushed to the above branch). This helped removing direct
  calls from the driver.
- Fix wrong usage of Pinning + Vec.
- Use Token for OPP Config.
- Use Opaque, transparent and Aref for few structures.
- Broken down into smaller patches to make it easy for reviewers.
- Based over staging/rust-device.

--
Viresh


Anisse Astier (1):
  rust: macros: enable use of hyphens in module names

Viresh Kumar (14):
  rust: cpumask: Add few more helpers
  rust: cpumask: Add initial abstractions
  MAINTAINERS: Add entry for Rust cpumask API
  rust: clk: Add helpers for Rust code
  rust: clk: Add initial abstractions
  rust: cpu: Add from_cpu()
  rust: opp: Add initial abstractions for OPP framework
  rust: opp: Add abstractions for the OPP table
  rust: opp: Add abstractions for the configuration options
  rust: cpufreq: Add initial abstractions for cpufreq framework
  rust: cpufreq: Extend abstractions for policy and driver ops
  rust: cpufreq: Extend abstractions for driver registration
  rust: opp: Extend OPP abstractions with cpufreq support
  cpufreq: Add Rust-based cpufreq-dt driver

 MAINTAINERS                     |   11 +
 drivers/cpufreq/Kconfig         |   12 +
 drivers/cpufreq/Makefile        |    1 +
 drivers/cpufreq/rcpufreq_dt.rs  |  229 ++++++
 rust/bindings/bindings_helper.h |    4 +
 rust/helpers/clk.c              |   66 ++
 rust/helpers/cpufreq.c          |   10 +
 rust/helpers/cpumask.c          |   25 +
 rust/helpers/helpers.c          |    2 +
 rust/kernel/clk.rs              |  334 ++++++++
 rust/kernel/cpu.rs              |   30 +
 rust/kernel/cpufreq.rs          | 1310 +++++++++++++++++++++++++++++++
 rust/kernel/cpumask.rs          |  330 ++++++++
 rust/kernel/lib.rs              |    7 +
 rust/kernel/opp.rs              | 1145 +++++++++++++++++++++++++++
 rust/macros/module.rs           |   20 +-
 16 files changed, 3528 insertions(+), 8 deletions(-)
 create mode 100644 drivers/cpufreq/rcpufreq_dt.rs
 create mode 100644 rust/helpers/clk.c
 create mode 100644 rust/helpers/cpufreq.c
 create mode 100644 rust/kernel/clk.rs
 create mode 100644 rust/kernel/cpu.rs
 create mode 100644 rust/kernel/cpufreq.rs
 create mode 100644 rust/kernel/cpumask.rs
 create mode 100644 rust/kernel/opp.rs

-- 
2.31.1.272.g89b43f80a514

[PATCH V12 01/15] rust: cpumask: Add few more helpers

[Viresh Kumar]

Add few more cpumask helpers that are required by the Rust abstraction.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Yury Norov [NVIDIA] <yury.norov@gmail.com>
---
 rust/helpers/cpumask.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
index 2d380a86c34a..eb10598a0242 100644
--- a/rust/helpers/cpumask.c
+++ b/rust/helpers/cpumask.c
@@ -7,16 +7,41 @@ void rust_helper_cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
 	cpumask_set_cpu(cpu, dstp);
 }
 
+void rust_helper___cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
+{
+	__cpumask_set_cpu(cpu, dstp);
+}
+
 void rust_helper_cpumask_clear_cpu(int cpu, struct cpumask *dstp)
 {
 	cpumask_clear_cpu(cpu, dstp);
 }
 
+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

[PATCH V12 02/15] rust: cpumask: Add initial abstractions

[Viresh Kumar]

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>
Reviewed-by: Yury Norov [NVIDIA] <yury.norov@gmail.com>
---
 rust/kernel/cpumask.rs | 330 +++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs     |   1 +
 2 files changed, 331 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..c90bfac9346a
--- /dev/null
+++ b/rust/kernel/cpumask.rs
@@ -0,0 +1,330 @@
+// 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},
+    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::as_mut_ref(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 as_mut_ref<'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 as_ref<'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 {
+        let this: *const Self = self;
+        this.cast_mut().cast()
+    }
+
+    /// Set `cpu` in the cpumask.
+    ///
+    /// 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`.
+        unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) };
+    }
+
+    /// Clear `cpu` in the cpumask.
+    ///
+    /// 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
+        // `__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_zero(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 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: 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.
+                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 instance of the [`CpumaskVar`].
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
+    /// getting used.
+    pub 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: 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.
+                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 as_mut_ref<'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 as_ref<'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_var is initialized right after this call.
+        let mut cpumask_var = unsafe { Self::new(GFP_KERNEL) }?;
+
+        cpumask.copy(&mut cpumask_var);
+        Ok(cpumask_var)
+    }
+}
+
+// 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

[PATCH V12 03/15] MAINTAINERS: Add entry for Rust cpumask API

[Viresh Kumar]

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

[PATCH V12 04/15] rust: clk: Add helpers for Rust code

[Viresh Kumar]

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

[PATCH V12 05/15] rust: clk: Add initial abstractions

[Viresh Kumar]

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 | 334 +++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs |   1 +
 3 files changed, 336 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..6041c6d07527
--- /dev/null
+++ b/rust/kernel/clk.rs
@@ -0,0 +1,334 @@
+// 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::ffi::c_ulong;
+
+/// 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
+    }
+}
+
+#[cfg(CONFIG_COMMON_CLK)]
+mod common_clk {
+    use super::Hertz;
+    use crate::{
+        device::Device,
+        error::{from_err_ptr, to_result, Result},
+        prelude::*,
+    };
+
+    use core::{ops::Deref, ptr};
+
+    /// 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()
+            } 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()
+            } 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
+        }
+    }
+}
+
+#[cfg(CONFIG_COMMON_CLK)]
+pub use common_clk::*;
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 75f78f6bfaa6..3fd7c17cbc06 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 clk;
 pub mod cpumask;
 pub mod cred;
 pub mod device;
-- 
2.31.1.272.g89b43f80a514

[PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

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

[PATCH V12 07/15] rust: cpu: Add from_cpu()

[Viresh Kumar]

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              | 30 ++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |  1 +
 4 files changed, 33 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..10c5c3b25873
--- /dev/null
+++ b/rust/kernel/cpu.rs
@@ -0,0 +1,30 @@
+// 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: It is safe to call `get_cpu_device()` for any CPU.
+    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 3fd7c17cbc06..de0a840fcc99 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -43,6 +43,7 @@
 #[doc(hidden)]
 pub mod build_assert;
 pub mod clk;
+pub mod cpu;
 pub mod cpumask;
 pub mod cred;
 pub mod device;
-- 
2.31.1.272.g89b43f80a514

[PATCH V12 08/15] rust: opp: Add initial abstractions for OPP framework

[Viresh Kumar]

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              | 299 ++++++++++++++++++++++++++++++++
 4 files changed, 303 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 de0a840fcc99..ea589254b4ac 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -67,6 +67,8 @@
 #[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..8f0493a8b6e8
--- /dev/null
+++ b/rust/kernel/opp.rs
@@ -0,0 +1,299 @@
+// 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::{
+    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

[PATCH V12 09/15] rust: opp: Add abstractions for the OPP table

[Viresh Kumar]

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 | 487 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 486 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 8f0493a8b6e8..18f55c00a4d6 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -10,8 +10,9 @@
 
 use crate::{
     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},
 };
@@ -171,6 +172,469 @@ 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>,
+    #[allow(dead_code)]
+    em: bool,
+    #[allow(dead_code)]
+    of: bool,
+    cpus: 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,
+            cpus: 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,
+            cpus: 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.cpus = 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.cpus.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 mut rate = freq.into();
+
+        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, rate, 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 rate, 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 rate, 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)
+            },
+
+            // 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)
+            },
+        })?;
+
+        // 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, 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, 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 the 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 the 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.cpus.take() {
+                self.remove_of_cpumask(&cpumask);
+            }
+        }
+    }
+}
+
 /// A reference-counted Operating performance point (OPP).
 ///
 /// Rust abstraction for the C `struct dev_pm_opp`.
@@ -184,6 +648,27 @@ 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

[PATCH V12 10/15] rust: opp: Add abstractions for the configuration options

[Viresh Kumar]

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 18f55c00a4d6..7be6fd33d93f 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -12,12 +12,29 @@
     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.
 ///
@@ -205,6 +222,280 @@ 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

[PATCH V12 11/15] rust: cpufreq: Add initial abstractions for cpufreq framework

[Viresh Kumar]

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          | 364 ++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |   2 +
 6 files changed, 379 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..2aa024615d4d
--- /dev/null
+++ b/rust/kernel/cpufreq.rs
@@ -0,0 +1,364 @@
+// 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::{
+    clk::Hertz,
+    error::{code::*, to_result, Result},
+    ffi::c_ulong,
+    prelude::*,
+    types::Opaque,
+};
+
+use core::{ops::Deref, 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 {
+    /// Driver needs to update internal limits even if frequency remains unchanged.
+    pub const NEED_UPDATE_LIMITS: u16 = 1 << 0;
+
+    /// Platform where constants like `loops_per_jiffy` are unaffected by frequency changes.
+    pub const CONST_LOOPS: u16 = 1 << 1;
+
+    /// Register driver as a thermal cooling device automatically.
+    pub const IS_COOLING_DEV: u16 = 1 << 2;
+
+    /// Supports multiple clock domains with per-policy governors in `cpu/cpuN/cpufreq/`.
+    pub const HAVE_GOVERNOR_PER_POLICY: u16 = 1 << 3;
+
+    /// Allows post-change notifications outside of the `target()` routine.
+    pub const ASYNC_NOTIFICATION: u16 = 1 << 4;
+
+    /// Ensure CPU starts at a valid frequency from the driver's freq-table.
+    pub const NEED_INITIAL_FREQ_CHECK: u16 = 1 << 5;
+
+    /// Disallow governors with `dynamic_switching` capability.
+    pub const NO_AUTO_DYNAMIC_SWITCHING: u16 = 1 << 6;
+}
+
+/// Relations from the C code.
+const CPUFREQ_RELATION_L: u32 = 0;
+const CPUFREQ_RELATION_H: u32 = 1;
+const CPUFREQ_RELATION_C: u32 = 2;
+
+/// Can be used with any of the above values.
+const CPUFREQ_RELATION_E: u32 = 1 << 2;
+
+/// 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 & CPUFREQ_RELATION_E != 0;
+
+        Ok(match val & !CPUFREQ_RELATION_E {
+            CPUFREQ_RELATION_L => Self::Low(efficient),
+            CPUFREQ_RELATION_H => Self::High(efficient),
+            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) => (CPUFREQ_RELATION_L, e),
+            Relation::High(e) => (CPUFREQ_RELATION_H, e),
+            Relation::Close(e) => (CPUFREQ_RELATION_C, e),
+        };
+
+        if efficient {
+            val |= 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 {
+        let this: *const Self = self;
+        this.cast_mut().cast()
+    }
+
+    /// 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()) })
+    }
+}
+
+/// The frequency table index.
+///
+/// Represents index with a frequency table.
+///
+/// # Invariants
+///
+/// The index must correspond to a valid entry in the [`Table`] it is used for.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct TableIndex(usize);
+
+impl TableIndex {
+    /// Creates an instance of [`TableIndex`].
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `index` correspond to a valid entry in the [`Table`] it is used
+    /// for.
+    pub unsafe fn new(index: usize) -> Self {
+        // INVARIANT: The caller ensures that `index` correspond to a valid entry in the [`Table`].
+        Self(index)
+    }
+}
+
+impl From<TableIndex> for usize {
+    #[inline]
+    fn from(index: TableIndex) -> Self {
+        index.0
+    }
+}
+
+/// 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, TableIndex};
+///
+/// fn show_freq(policy: &Policy) {
+///     let table = policy.freq_table().unwrap();
+///
+///     // SAFETY: Index is a valid entry in the table.
+///     let index = unsafe { TableIndex::new(0) };
+///
+///     pr_info!("The frequency at index 0 is: {:?}\n", table.freq(index).unwrap());
+///     pr_info!("The flags at index 0 is: {}\n", table.flags(index));
+///     pr_info!("The data at index 0 is: {}\n", table.data(index));
+/// }
+/// ```
+#[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 {
+        let this: *const Self = self;
+        this.cast_mut().cast()
+    }
+
+    /// Returns frequency at `index` in the [`Table`].
+    #[inline]
+    pub fn freq(&self, index: TableIndex) -> Result<Hertz> {
+        // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+        // guaranteed to be valid by its safety requirements.
+        Ok(Hertz::from_khz(unsafe {
+            (*self.as_raw().add(index.into())).frequency.try_into()?
+        }))
+    }
+
+    /// Returns flags at `index` in the [`Table`].
+    #[inline]
+    pub fn flags(&self, index: TableIndex) -> u32 {
+        // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+        // guaranteed to be valid by its safety requirements.
+        unsafe { (*self.as_raw().add(index.into())).flags }
+    }
+
+    /// Returns data at `index` in the [`Table`].
+    #[inline]
+    pub fn data(&self, index: TableIndex) -> u32 {
+        // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is
+        // guaranteed to be valid by its safety requirements.
+        unsafe { (*self.as_raw().add(index.into())).driver_data }
+    }
+}
+
+/// CPU frequency table owned and pinned in memory, created from a [`TableBuilder`].
+pub struct TableBox {
+    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, TableIndex};
+/// 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: Index values correspond to valid entries in the table.
+/// let (index0, index2) = unsafe { (TableIndex::new(0), TableIndex::new(2)) };
+///
+/// assert_eq!(table.freq(index0), Ok(Hertz::from_mhz(700)));
+/// assert_eq!(table.flags(index0), 0);
+/// assert_eq!(table.data(index0), 1);
+///
+/// assert_eq!(table.freq(index2), Ok(Hertz::from_mhz(900)));
+/// assert_eq!(table.flags(index2), 4);
+/// assert_eq!(table.data(index2), 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 ea589254b4ac..133ebee4f9d3 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -44,6 +44,8 @@
 pub mod build_assert;
 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

[PATCH V12 12/15] rust: cpufreq: Extend abstractions for policy and driver ops

[Viresh Kumar]

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 | 463 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 461 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 2aa024615d4d..4e6d85bd06f4 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -10,13 +10,25 @@
 
 use crate::{
     clk::Hertz,
-    error::{code::*, to_result, Result},
+    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, pin::Pin};
+#[cfg(CONFIG_COMMON_CLK)]
+use crate::clk::Clk;
+
+use core::{
+    ops::{Deref, DerefMut},
+    pin::Pin,
+    ptr,
+};
+
+use macros::vtable;
 
 /// Default transition latency value in nanoseconds.
 pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32;
@@ -362,3 +374,450 @@ 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 {
+        let this: *const Self = self;
+        this.cast_mut().cast()
+    }
+
+    #[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::as_mut_ref(&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.
+    #[cfg(CONFIG_COMMON_CLK)]
+    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's name.
+    const NAME: &'static CStr;
+
+    /// Driver's flags.
+    const FLAGS: u16;
+
+    /// Boost support.
+    const BOOST_ENABLED: bool;
+
+    /// 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: TableIndex) -> 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: TableIndex) -> u32 {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Driver's `target_intermediate` callback.
+    fn target_intermediate(_policy: &mut Policy, _index: TableIndex) -> 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

[PATCH V12 13/15] rust: cpufreq: Extend abstractions for driver registration

[Viresh Kumar]

Extend the cpufreq abstractions to support driver registration from
Rust.

Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/cpufreq.rs | 493 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 490 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 4e6d85bd06f4..826710c4f4b0 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -11,9 +11,10 @@
 use crate::{
     clk::Hertz,
     cpumask,
-    device::Device,
-    error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
-    ffi::c_ulong,
+    device::{Bound, Device},
+    devres::Devres,
+    error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
+    ffi::{c_char, c_ulong},
     prelude::*,
     types::ForeignOwnable,
     types::Opaque,
@@ -23,6 +24,9 @@
 use crate::clk::Clk;
 
 use core::{
+    cell::UnsafeCell,
+    marker::PhantomData,
+    mem::MaybeUninit,
     ops::{Deref, DerefMut},
     pin::Pin,
     ptr,
@@ -30,6 +34,9 @@
 
 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;
 
@@ -821,3 +828,483 @@ 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::{
+///     cpu, cpufreq,
+///     c_str,
+///     device::{Bound, Device},
+///     macros::vtable,
+///     sync::Arc,
+/// };
+/// struct FooDevice;
+///
+/// #[derive(Default)]
+/// struct FooDriver;
+///
+/// #[vtable]
+/// impl cpufreq::Driver for FooDriver {
+///     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> {
+///         // 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: cpufreq::TableIndex) -> Result<()> {
+///         // Update CPU frequency
+///         Ok(())
+///     }
+///
+///     fn get(policy: &mut cpufreq::Policy) -> Result<u32> {
+///         policy.generic_get()
+///     }
+/// }
+///
+/// fn foo_probe(dev: &Device<Bound>) {
+///     cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
+/// }
+/// ```
+#[repr(transparent)]
+pub struct Registration<T: Driver>(KBox<UnsafeCell<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.
+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.
+unsafe impl<T: Driver> Send for Registration<T> {}
+
+impl<T: Driver> Registration<T> {
+    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.
+        init: Some(Self::init_callback),
+        verify: Some(Self::verify_callback),
+
+        // Initialize optional callbacks based on the traits of `T`.
+        setpolicy: if T::HAS_SETPOLICY {
+            Some(Self::setpolicy_callback)
+        } else {
+            None
+        },
+        target: if T::HAS_TARGET {
+            Some(Self::target_callback)
+        } else {
+            None
+        },
+        target_index: if T::HAS_TARGET_INDEX {
+            Some(Self::target_index_callback)
+        } else {
+            None
+        },
+        fast_switch: if T::HAS_FAST_SWITCH {
+            Some(Self::fast_switch_callback)
+        } else {
+            None
+        },
+        adjust_perf: if T::HAS_ADJUST_PERF {
+            Some(Self::adjust_perf_callback)
+        } else {
+            None
+        },
+        get_intermediate: if T::HAS_GET_INTERMEDIATE {
+            Some(Self::get_intermediate_callback)
+        } else {
+            None
+        },
+        target_intermediate: if T::HAS_TARGET_INTERMEDIATE {
+            Some(Self::target_intermediate_callback)
+        } else {
+            None
+        },
+        get: if T::HAS_GET {
+            Some(Self::get_callback)
+        } else {
+            None
+        },
+        update_limits: if T::HAS_UPDATE_LIMITS {
+            Some(Self::update_limits_callback)
+        } else {
+            None
+        },
+        bios_limit: if T::HAS_BIOS_LIMIT {
+            Some(Self::bios_limit_callback)
+        } else {
+            None
+        },
+        online: if T::HAS_ONLINE {
+            Some(Self::online_callback)
+        } else {
+            None
+        },
+        offline: if T::HAS_OFFLINE {
+            Some(Self::offline_callback)
+        } else {
+            None
+        },
+        exit: if T::HAS_EXIT {
+            Some(Self::exit_callback)
+        } else {
+            None
+        },
+        suspend: if T::HAS_SUSPEND {
+            Some(Self::suspend_callback)
+        } else {
+            None
+        },
+        resume: if T::HAS_RESUME {
+            Some(Self::resume_callback)
+        } else {
+            None
+        },
+        ready: if T::HAS_READY {
+            Some(Self::ready_callback)
+        } else {
+            None
+        },
+        set_boost: if T::HAS_SET_BOOST {
+            Some(Self::set_boost_callback)
+        } else {
+            None
+        },
+        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> {
+        // We can't use `&Self::VTABLE` directly because the cpufreq core modifies some fields in
+        // the C `struct cpufreq_driver`, which requires a mutable reference.
+        let mut drv = KBox::new(UnsafeCell::new(Self::VTABLE), GFP_KERNEL)?;
+
+        // SAFETY: `drv` is guaranteed to be valid for the lifetime of `Registration`.
+        to_result(unsafe { bindings::cpufreq_register_driver(drv.get_mut()) })?;
+
+        Ok(Self(drv, 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<Bound>) -> Result<()> {
+        Devres::new_foreign_owned(dev, Self::new()?, GFP_KERNEL)
+    }
+}
+
+/// 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) };
+
+            // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the
+            // frequency table.
+            let index = unsafe { TableIndex::new(index as usize) };
+
+            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) };
+
+        // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the
+        // frequency table.
+        let index = unsafe { TableIndex::new(index as usize) };
+
+        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) };
+
+            // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the
+            // frequency table.
+            let index = unsafe { TableIndex::new(index as usize) };
+
+            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(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::update_limits(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> {
+    /// Unregisters with the cpufreq core.
+    fn drop(&mut self) {
+        // SAFETY: `self.0` is guaranteed to be valid for the lifetime of `Registration`.
+        unsafe { bindings::cpufreq_unregister_driver(self.0.get_mut()) };
+    }
+}
-- 
2.31.1.272.g89b43f80a514

[PATCH V12 14/15] rust: opp: Extend OPP abstractions with cpufreq support

[Viresh Kumar]

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 | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 7be6fd33d93f..1e5fd9887b3a 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -19,6 +19,69 @@
     types::{ARef, AlwaysRefCounted, Opaque},
 };
 
+#[cfg(CONFIG_CPU_FREQ)]
+/// Frequency table implementation.
+mod freq {
+    use super::*;
+    use crate::cpufreq;
+    use core::ops::Deref;
+
+    /// OPP frequency table.
+    ///
+    /// A [`cpufreq::Table`] created from [`Table`].
+    pub struct FreqTable {
+        dev: ARef<Device>,
+        ptr: *mut bindings::cpufreq_frequency_table,
+    }
+
+    impl FreqTable {
+        /// Creates a new instance of [`FreqTable`] from [`Table`].
+        pub(crate) 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) }
+        }
+    }
+
+    impl Deref for FreqTable {
+        type Target = cpufreq::Table;
+
+        #[inline]
+        fn deref(&self) -> &Self::Target {
+            self.table()
+        }
+    }
+
+    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())
+            };
+        }
+    }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+pub use freq::FreqTable;
+
 use core::{marker::PhantomData, ptr};
 
 use macros::vtable;
@@ -753,6 +816,13 @@ 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

[PATCH V12 15/15] cpufreq: Add Rust-based cpufreq-dt driver

[Viresh Kumar]

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 | 229 +++++++++++++++++++++++++++++++++
 3 files changed, 242 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..d0e60b7db81f
--- /dev/null
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -0,0 +1,229 @@
+// 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,
+    _mask: CpumaskVar,
+    _token: Option<opp::ConfigToken>,
+    _clk: Clk,
+}
+
+#[derive(Default)]
+struct CPUFreqDTDriver;
+
+#[vtable]
+impl opp::ConfigOps for CPUFreqDTDriver {}
+
+#[vtable]
+impl cpufreq::Driver for CPUFreqDTDriver {
+    const NAME: &'static 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> {
+        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_zero(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: mask,
+                _token: token,
+                _clk: 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: cpufreq::TableIndex) -> Result<()> {
+        let Some(data) = policy.data::<Self::PData>() else {
+            return Err(ENOENT);
+        };
+
+        let freq = data.freq_table.freq(index)?;
+        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())?;
+
+        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

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Benno Lossin]

On Mon May 19, 2025 at 9:07 AM CEST, Viresh Kumar wrote:
> 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.

I think this is supposed to read "But Rust identifier cannot contain
hyphens, so replace them with underscores.".

> 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(-)

One nit below, with or without:

Reviewed-by: Benno Lossin <lossin@kernel.org>

> 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('-', "_");

I think we could just name this variable `ident`.

---
Cheers,
Benno

> +    let mut modinfo = ModInfoBuilder::new(name_identifier.as_ref());
>      if let Some(author) = info.author {
>          modinfo.emit("author", &author);
>      }

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

On 19-05-25, 10:00, Benno Lossin wrote:
> I think this is supposed to read "But Rust identifier cannot contain
> hyphens, so replace them with underscores.".
 
> I think we could just name this variable `ident`.

Fixed both. Thanks.

-- 
viresh

Re: [PATCH V12 13/15] rust: cpufreq: Extend abstractions for driver registration

[Danilo Krummrich]

On Mon, May 19, 2025 at 12:37:18PM +0530, Viresh Kumar wrote:
> +/// CPU frequency driver Registration.
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to register a cpufreq driver.
> +///
> +/// ```
> +/// use kernel::{
> +///     cpu, cpufreq,
> +///     c_str,
> +///     device::{Bound, Device},
> +///     macros::vtable,
> +///     sync::Arc,
> +/// };
> +/// struct FooDevice;
> +///
> +/// #[derive(Default)]
> +/// struct FooDriver;
> +///
> +/// #[vtable]
> +/// impl cpufreq::Driver for FooDriver {
> +///     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> {
> +///         // Initialize here
> +///         Ok(Arc::new(FooDevice, GFP_KERNEL)?)
> +///     }
> +///
> +///     fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {

This can just be `Result`, here and below.

> +///         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: cpufreq::TableIndex) -> Result<()> {
> +///         // Update CPU frequency
> +///         Ok(())
> +///     }
> +///
> +///     fn get(policy: &mut cpufreq::Policy) -> Result<u32> {
> +///         policy.generic_get()
> +///     }
> +/// }
> +///
> +/// fn foo_probe(dev: &Device<Bound>) {

You could use a real probe function, e.g. from platform:

	# struct Driver;
	
	impl platform::Driver for SampleDriver {
	   # type IdInfo = ();
	   # const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
	
	   fn probe(
	      pdev: &platform::Device<Core>,
	      info: Option<&Self::IdInfo>,
	   ) -> Result<Pin<KBox<Self>>> {
	      ...
	   }
	}

> +///     cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();

I prefer if we do not use unwrap() in doctests, since they also serve as example
and people might think that calling unwrap() is valid thing to do.

Sorry, I didn't catch the above in my previous review -- fine for me if you do
those improvements in a subsequent patch.

Re: [PATCH V12 13/15] rust: cpufreq: Extend abstractions for driver registration

[Benno Lossin]

On Mon May 19, 2025 at 1:06 PM CEST, Danilo Krummrich wrote:
> On Mon, May 19, 2025 at 12:37:18PM +0530, Viresh Kumar wrote:
>> +///     fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
>
> This can just be `Result`, here and below.

Since I saw you mention this multiple times and I agree, I created a
clippy issue: https://github.com/rust-lang/rust-clippy/issues/14848

---
Cheers,
Benno

Re: [PATCH V12 13/15] rust: cpufreq: Extend abstractions for driver registration

[Miguel Ojeda]

On Mon, May 19, 2025 at 1:41 PM Benno Lossin <lossin@kernel.org> wrote:
>
> Since I saw you mention this multiple times and I agree, I created a
> clippy issue: https://github.com/rust-lang/rust-clippy/issues/14848

This is https://github.com/Rust-for-Linux/linux/issues/1128 -- I agree
having it done in Clippy in a general way would be ideal.

Thanks!

Cheers,
Miguel

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Miguel Ojeda]

On Mon, May 19, 2025 at 9:08 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> +    /* Rust does not allow hyphens in identifiers, use underscore instead */

(In case you see this before you apply)

Nit: `//` for comments, also please end with a period.

Cheers,
Miguel

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

On 19-05-25, 16:15, Miguel Ojeda wrote:
> On Mon, May 19, 2025 at 9:08 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> > +    /* Rust does not allow hyphens in identifiers, use underscore instead */
> 
> (In case you see this before you apply)
> 
> Nit: `//` for comments, also please end with a period.

Done.

-- 
viresh

Re: [PATCH V12 13/15] rust: cpufreq: Extend abstractions for driver registration

[Viresh Kumar]

On 19-05-25, 13:06, Danilo Krummrich wrote:
> Sorry, I didn't catch the above in my previous review -- fine for me if you do
> those improvements in a subsequent patch.

That's fine. Thanks a lot for reviewing the series.

-- 
viresh

diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
index d0e60b7db81f..94ed81644fe1 100644
--- a/drivers/cpufreq/rcpufreq_dt.rs
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -152,30 +152,30 @@ fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
         )?)
     }
 
-    fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
+    fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result {
         Ok(())
     }
 
-    fn online(_policy: &mut cpufreq::Policy) -> Result<()> {
+    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<()> {
+    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<()> {
+    fn suspend(policy: &mut cpufreq::Policy) -> Result {
         policy.generic_suspend()
     }
 
-    fn verify(data: &mut cpufreq::PolicyData) -> Result<()> {
+    fn verify(data: &mut cpufreq::PolicyData) -> Result {
         data.generic_verify()
     }
 
-    fn target_index(policy: &mut cpufreq::Policy, index: cpufreq::TableIndex) -> Result<()> {
+    fn target_index(policy: &mut cpufreq::Policy, index: cpufreq::TableIndex) -> Result {
         let Some(data) = policy.data::<Self::PData>() else {
             return Err(ENOENT);
         };
@@ -188,7 +188,7 @@ fn get(policy: &mut cpufreq::Policy) -> Result<u32> {
         policy.generic_get()
     }
 
-    fn set_boost(_policy: &mut cpufreq::Policy, _state: i32) -> Result<()> {
+    fn set_boost(_policy: &mut cpufreq::Policy, _state: i32) -> Result {
         Ok(())
     }
 
@@ -213,10 +213,7 @@ fn probe(
         _id_info: Option<&Self::IdInfo>,
     ) -> Result<Pin<KBox<Self>>> {
         cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(pdev.as_ref())?;
-
-        let drvdata = KBox::new(Self {}, GFP_KERNEL)?;
-
-        Ok(drvdata.into())
+        Ok(KBox::new(Self {}, GFP_KERNEL)?.into())
     }
 }
 
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 826710c4f4b0..09b856bb297b 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -154,7 +154,7 @@ pub fn as_raw(&self) -> *mut bindings::cpufreq_policy_data {
 
     /// Wrapper for `cpufreq_generic_frequency_table_verify`.
     #[inline]
-    pub fn generic_verify(&self) -> Result<()> {
+    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()) })
     }
@@ -208,15 +208,16 @@ fn from(index: TableIndex) -> Self {
 /// ```
 /// use kernel::cpufreq::{Policy, TableIndex};
 ///
-/// fn show_freq(policy: &Policy) {
-///     let table = policy.freq_table().unwrap();
+/// fn show_freq(policy: &Policy) -> Result {
+///     let table = policy.freq_table()?;
 ///
 ///     // SAFETY: Index is a valid entry in the table.
 ///     let index = unsafe { TableIndex::new(0) };
 ///
-///     pr_info!("The frequency at index 0 is: {:?}\n", table.freq(index).unwrap());
+///     pr_info!("The frequency at index 0 is: {:?}\n", table.freq(index)?);
 ///     pr_info!("The flags at index 0 is: {}\n", table.flags(index));
 ///     pr_info!("The data at index 0 is: {}\n", table.data(index));
+///     Ok(())
 /// }
 /// ```
 #[repr(transparent)]
@@ -361,7 +362,7 @@ pub fn new() -> Self {
     }
 
     /// Adds a new entry to the table.
-    pub fn add(&mut self, freq: Hertz, flags: u32, driver_data: u32) -> Result<()> {
+    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 {
@@ -515,7 +516,7 @@ pub fn set_suspend_freq(&mut self, freq: Hertz) -> &mut Self {
 
     /// Provides a wrapper to the generic suspend routine.
     #[inline]
-    pub fn generic_suspend(&mut self) -> Result<()> {
+    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()) })
     }
@@ -643,7 +644,7 @@ pub fn data<T: ForeignOwnable>(&mut self) -> Option<<T>::Borrowed<'_>> {
     /// # Errors
     ///
     /// Returns `EBUSY` if private data is already set.
-    fn set_data<T: ForeignOwnable>(&mut self, data: T) -> Result<()> {
+    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 _;
@@ -736,27 +737,27 @@ pub trait Driver {
     fn init(policy: &mut Policy) -> Result<Self::PData>;
 
     /// Driver's `exit` callback.
-    fn exit(_policy: &mut Policy, _data: Option<Self::PData>) -> Result<()> {
+    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<()> {
+    fn online(_policy: &mut Policy) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
     /// Driver's `offline` callback.
-    fn offline(_policy: &mut Policy) -> Result<()> {
+    fn offline(_policy: &mut Policy) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
     /// Driver's `suspend` callback.
-    fn suspend(_policy: &mut Policy) -> Result<()> {
+    fn suspend(_policy: &mut Policy) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
     /// Driver's `resume` callback.
-    fn resume(_policy: &mut Policy) -> Result<()> {
+    fn resume(_policy: &mut Policy) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -766,20 +767,20 @@ fn ready(_policy: &mut Policy) {
     }
 
     /// Driver's `verify` callback.
-    fn verify(data: &mut PolicyData) -> Result<()>;
+    fn verify(data: &mut PolicyData) -> Result;
 
     /// Driver's `setpolicy` callback.
-    fn setpolicy(_policy: &mut Policy) -> Result<()> {
+    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<()> {
+    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: TableIndex) -> Result<()> {
+    fn target_index(_policy: &mut Policy, _index: TableIndex) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -799,7 +800,7 @@ fn get_intermediate(_policy: &mut Policy, _index: TableIndex) -> u32 {
     }
 
     /// Driver's `target_intermediate` callback.
-    fn target_intermediate(_policy: &mut Policy, _index: TableIndex) -> Result<()> {
+    fn target_intermediate(_policy: &mut Policy, _index: TableIndex) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -814,12 +815,12 @@ fn update_limits(_policy: &mut Policy) {
     }
 
     /// Driver's `bios_limit` callback.
-    fn bios_limit(_policy: &mut Policy, _limit: &mut u32) -> Result<()> {
+    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<()> {
+    fn set_boost(_policy: &mut Policy, _state: i32) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -837,43 +838,44 @@ fn register_em(_policy: &mut Policy) {
 ///
 /// ```
 /// use kernel::{
-///     cpu, cpufreq,
+///     cpufreq,
 ///     c_str,
-///     device::{Bound, Device},
+///     device::{Core, Device},
 ///     macros::vtable,
+///     of, platform,
 ///     sync::Arc,
 /// };
-/// struct FooDevice;
+/// struct SampleDevice;
 ///
 /// #[derive(Default)]
-/// struct FooDriver;
+/// struct SampleDriver;
 ///
 /// #[vtable]
-/// impl cpufreq::Driver for FooDriver {
-///     const NAME: &'static CStr = c_str!("cpufreq-foo");
+/// impl cpufreq::Driver for SampleDriver {
+///     const NAME: &'static CStr = c_str!("cpufreq-sample");
 ///     const FLAGS: u16 = cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV;
 ///     const BOOST_ENABLED: bool = true;
 ///
-///     type PData = Arc<FooDevice>;
+///     type PData = Arc<SampleDevice>;
 ///
 ///     fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
 ///         // Initialize here
-///         Ok(Arc::new(FooDevice, GFP_KERNEL)?)
+///         Ok(Arc::new(SampleDevice, GFP_KERNEL)?)
 ///     }
 ///
-///     fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
+///     fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result {
 ///         Ok(())
 ///     }
 ///
-///     fn suspend(policy: &mut cpufreq::Policy) -> Result<()> {
+///     fn suspend(policy: &mut cpufreq::Policy) -> Result {
 ///         policy.generic_suspend()
 ///     }
 ///
-///     fn verify(data: &mut cpufreq::PolicyData) -> Result<()> {
+///     fn verify(data: &mut cpufreq::PolicyData) -> Result {
 ///         data.generic_verify()
 ///     }
 ///
-///     fn target_index(policy: &mut cpufreq::Policy, index: cpufreq::TableIndex) -> Result<()> {
+///     fn target_index(policy: &mut cpufreq::Policy, index: cpufreq::TableIndex) -> Result {
 ///         // Update CPU frequency
 ///         Ok(())
 ///     }
@@ -883,8 +885,17 @@ fn register_em(_policy: &mut Policy) {
 ///     }
 /// }
 ///
-/// fn foo_probe(dev: &Device<Bound>) {
-///     cpufreq::Registration::<FooDriver>::new_foreign_owned(dev).unwrap();
+/// impl platform::Driver for SampleDriver {
+///     type IdInfo = ();
+///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
+///
+///     fn probe(
+///         pdev: &platform::Device<Core>,
+///         _id_info: Option<&Self::IdInfo>,
+///     ) -> Result<Pin<KBox<Self>>> {
+///         cpufreq::Registration::<SampleDriver>::new_foreign_owned(pdev.as_ref())?;
+///         Ok(KBox::new(Self {}, GFP_KERNEL)?.into())
+///     }
 /// }
 /// ```
 #[repr(transparent)]
@@ -1035,7 +1046,7 @@ pub fn new() -> Result<Self> {
     ///
     /// Instead the [`Registration`] is owned by [`Devres`] and will be revoked / dropped, once the
     /// device is detached.
-    pub fn new_foreign_owned(dev: &Device<Bound>) -> Result<()> {
+    pub fn new_foreign_owned(dev: &Device<Bound>) -> Result {
         Devres::new_foreign_owned(dev, Self::new()?, GFP_KERNEL)
     }
 }
diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 1e5fd9887b3a..212555dacd45 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -292,7 +292,7 @@ pub enum SearchType {
 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<()> {
+    fn config_clks(_dev: &Device, _table: &Table, _opp: &OPP, _scaling_down: bool) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -304,7 +304,7 @@ fn config_regulators(
         _opp_new: &OPP,
         _data: *mut *mut bindings::regulator,
         _count: u32,
-    ) -> Result<()> {
+    ) -> Result {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 }
@@ -753,7 +753,7 @@ pub fn suspend_freq(&self) -> Hertz {
 
     /// Synchronizes regulators used by the [`Table`].
     #[inline]
-    pub fn sync_regulators(&self) -> Result<()> {
+    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()) })
@@ -761,14 +761,14 @@ pub fn sync_regulators(&self) -> Result<()> {
 
     /// Gets sharing CPUs.
     #[inline]
-    pub fn sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result<()> {
+    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<()> {
+    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 {
@@ -786,7 +786,7 @@ pub fn set_sharing_cpus(&mut self, cpumask: &mut Cpumask) -> Result<()> {
     /// Gets sharing CPUs from device tree.
     #[cfg(CONFIG_OF)]
     #[inline]
-    pub fn of_sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result<()> {
+    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 {
@@ -802,7 +802,7 @@ pub fn adjust_voltage(
         volt: MicroVolt,
         volt_min: MicroVolt,
         volt_max: MicroVolt,
-    ) -> Result<()> {
+    ) -> Result {
         // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
         // requirements.
         to_result(unsafe {
@@ -825,7 +825,7 @@ pub fn cpufreq_table(&mut self) -> Result<FreqTable> {
 
     /// Configures device with [`OPP`] matching the frequency value.
     #[inline]
-    pub fn set_rate(&self, freq: Hertz) -> Result<()> {
+    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()) })
@@ -833,7 +833,7 @@ pub fn set_rate(&self, freq: Hertz) -> Result<()> {
 
     /// Configures device with [`OPP`].
     #[inline]
-    pub fn set_opp(&self, opp: &OPP) -> Result<()> {
+    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()) })
@@ -937,7 +937,7 @@ pub fn opp_from_bw(&self, mut bw: u32, index: i32, stype: SearchType) -> Result<
 
     /// Enables the [`OPP`].
     #[inline]
-    pub fn enable_opp(&self, freq: Hertz) -> Result<()> {
+    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()) })
@@ -945,7 +945,7 @@ pub fn enable_opp(&self, freq: Hertz) -> Result<()> {
 
     /// Disables the [`OPP`].
     #[inline]
-    pub fn disable_opp(&self, freq: Hertz) -> Result<()> {
+    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()) })
@@ -953,7 +953,7 @@ pub fn disable_opp(&self, freq: Hertz) -> Result<()> {
 
     /// Registers with the Energy model.
     #[cfg(CONFIG_OF)]
-    pub fn of_register_em(&mut self, cpumask: &mut Cpumask) -> Result<()> {
+    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 {
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 27cc72d474f0..6ff34096d7ee 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -185,9 +185,9 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
 
     let info = ModuleInfo::parse(&mut it);
 
-    /* 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());
+    // Rust does not allow hyphens in identifiers, use underscore instead.
+    let ident = info.name.replace('-', "_");
+    let mut modinfo = ModInfoBuilder::new(ident.as_ref());
     if let Some(author) = info.author {
         modinfo.emit("author", &author);
     }
@@ -312,15 +312,15 @@ mod __module_init {{
                     #[doc(hidden)]
                     #[link_section = \"{initcall_section}\"]
                     #[used]
-                    pub static __{name_identifier}_initcall: extern \"C\" fn() ->
-                        kernel::ffi::c_int = __{name_identifier}_init;
+                    pub static __{ident}_initcall: extern \"C\" fn() ->
+                        kernel::ffi::c_int = __{ident}_init;
 
                     #[cfg(not(MODULE))]
                     #[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
                     core::arch::global_asm!(
                         r#\".section \"{initcall_section}\", \"a\"
-                        __{name_identifier}_initcall:
-                            .long   __{name_identifier}_init - .
+                        __{ident}_initcall:
+                            .long   __{ident}_init - .
                             .previous
                         \"#
                     );
@@ -328,7 +328,7 @@ mod __module_init {{
                     #[cfg(not(MODULE))]
                     #[doc(hidden)]
                     #[no_mangle]
-                    pub extern \"C\" fn __{name_identifier}_init() -> kernel::ffi::c_int {{
+                    pub extern \"C\" fn __{ident}_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.
@@ -338,12 +338,12 @@ mod __module_init {{
                     #[cfg(not(MODULE))]
                     #[doc(hidden)]
                     #[no_mangle]
-                    pub extern \"C\" fn __{name_identifier}_exit() {{
+                    pub extern \"C\" fn __{ident}_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_identifier}_init` has
+                        // - furthermore it is only called after `__{ident}_init` has
                         //   returned `0` (which delegates to `__init`).
                         unsafe {{ __exit() }}
                     }}
@@ -384,7 +384,7 @@ unsafe fn __exit() {{
         ",
         type_ = info.type_,
         name = info.name,
-        name_identifier = name_identifier,
+        ident = ident,
         modinfo = modinfo.buffer,
         initcall_section = ".initcall6.init"
     )

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Anisse Astier]

Mar 20 mai 2025, à 06:33, Viresh Kumar a écrit :
> On 19-05-25, 16:15, Miguel Ojeda wrote:
>> On Mon, May 19, 2025 at 9:08 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>> >
>> > +    /* Rust does not allow hyphens in identifiers, use underscore instead */
>> 
>> (In case you see this before you apply)
>> 
>> Nit: `//` for comments, also please end with a period.
>
> Done.

Thank you Viresh for iterating on this and picking up review comments. Do not hesitate to add your Co-developed-by.

Kind regards,

Anisse

Re: [PATCH V12 06/15] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

On 20-05-25, 08:13, Anisse Astier wrote:
> Thank you Viresh for iterating on this and picking up review
> comments. Do not hesitate to add your Co-developed-by.

I haven't added Co-developed-by, but I did mention the changes I have
made in the cover-letter. This is all your work and thanks a lot for
this patch. I was struggling with this for quite some time and was
desperately looking for help :)

-- 
viresh

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Viresh Kumar]

On 19-05-25, 12:37, Viresh Kumar wrote:
> I have queued this up for v6.16-rc1, will merge it via the PM tree soon.
> Thanks.

Sent for inclusion in the PM tree for 6.16. Thanks everyone for
reviewing the work.

https://lore.kernel.org/all/20250520061944.pl3mqw2clo2roe3s@vireshk-i7/

-- 
viresh

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Andreas Hindborg]

Hi Viresh,

"Viresh Kumar" <viresh.kumar@linaro.org> writes:

> Hello,
>
> I have queued this up for v6.16-rc1, will merge it via the PM tree soon.
> Thanks.
>
> This series introduces initial Rust abstractions for a few subsystems: clk,
> cpumask, cpufreq and Operating Performance Points (OPP).
>
> The abstractions cover most of the interfaces exposed by cpufreq and OPP
> subsystems. It also includes minimal abstractions for the clk and cpumask
> frameworks, which are required by the cpufreq / OPP abstractions.
>
> Additionally, a sample `rcpufreq-dt` driver is included. This is a
> duplicate of the existing `cpufreq-dt` driver, which is a
> platform-agnostic, device-tree based cpufreq driver commonly used on ARM
> platforms.
>
> The implementation has been tested using QEMU, ensuring that frequency
> transitions, various configurations, and driver binding/unbinding work as
> expected. However, performance measurements have not been conducted yet.
>
> For those interested in testing these patches, they can be found at:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git rust/cpufreq-dt
>
> Based on 6.15-rc1 + rust/devres dependencies + PM/cpufreq dependencies.

I was testing an unrelated patch and found this kunit failure in
mainline today:

[19:45:34] # rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180
[19:45:34] # rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190

This is for arm64 defconfig. The test seems to passes on x86_64.


Best regards,
Andreas Hindborg

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Boqun Feng]

On Thu, Jun 05, 2025 at 09:41:47PM +0200, Andreas Hindborg wrote:
> Hi Viresh,
> 
> "Viresh Kumar" <viresh.kumar@linaro.org> writes:
> 
> > Hello,
> >
> > I have queued this up for v6.16-rc1, will merge it via the PM tree soon.
> > Thanks.
> >
> > This series introduces initial Rust abstractions for a few subsystems: clk,
> > cpumask, cpufreq and Operating Performance Points (OPP).
> >
> > The abstractions cover most of the interfaces exposed by cpufreq and OPP
> > subsystems. It also includes minimal abstractions for the clk and cpumask
> > frameworks, which are required by the cpufreq / OPP abstractions.
> >
> > Additionally, a sample `rcpufreq-dt` driver is included. This is a
> > duplicate of the existing `cpufreq-dt` driver, which is a
> > platform-agnostic, device-tree based cpufreq driver commonly used on ARM
> > platforms.
> >
> > The implementation has been tested using QEMU, ensuring that frequency
> > transitions, various configurations, and driver binding/unbinding work as
> > expected. However, performance measurements have not been conducted yet.
> >
> > For those interested in testing these patches, they can be found at:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git rust/cpufreq-dt
> >
> > Based on 6.15-rc1 + rust/devres dependencies + PM/cpufreq dependencies.
> 
> I was testing an unrelated patch and found this kunit failure in
> mainline today:
> 
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190
> 

I assume you run it in a VM? How many vcpus are you using? I've checked
the code, cpumask_{set,test}() can set or set bits out of nr_cpu_ids
without triggering warning if CONFIG_DEBUG_PER_CPU_MAPS=n, but
cpumask_weight() only examine nr_cpu_ids bits. So if you run with
nr_cpu_ids < 4, the test case may fail.

Regards,
Boqun

> This is for arm64 defconfig. The test seems to passes on x86_64.
> 
> 
> Best regards,
> Andreas Hindborg
> 
> 

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Viresh Kumar]

On 05-06-25, 21:41, Andreas Hindborg wrote:
> I was testing an unrelated patch and found this kunit failure in
> mainline today:
> 
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190
> 
> This is for arm64 defconfig. The test seems to passes on x86_64.

Posted a fix:

https://lore.kernel.org/all/8b5fc7889a7aacbd9f1f7412c99f02c736bde190.1749183428.git.viresh.kumar@linaro.org/

-- 
viresh

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Viresh Kumar]

On 05-06-25, 13:12, Boqun Feng wrote:
> I assume you run it in a VM? How many vcpus are you using? I've checked
> the code, cpumask_{set,test}() can set or set bits out of nr_cpu_ids
> without triggering warning if CONFIG_DEBUG_PER_CPU_MAPS=n, but
> cpumask_weight() only examine nr_cpu_ids bits. So if you run with
> nr_cpu_ids < 4, the test case may fail.

Ahh, thanks for that. It was really helpful.

-- 
viresh

Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

[Miguel Ojeda]

On Thu, Jun 5, 2025 at 9:42 PM Andreas Hindborg <a.hindborg@kernel.org> wrote:
>
> I was testing an unrelated patch and found this kunit failure in
> mainline today:
>
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190
>
> This is for arm64 defconfig. The test seems to passes on x86_64.

Yeah, I reported this back in v11:

    https://lore.kernel.org/rust-for-linux/CANiq72k3ozKkLMinTLQwvkyg9K=BeRxs1oYZSKhJHY-veEyZdg@mail.gmail.com/

No harm done, but let's please try to avoid merging new stuff into
mainline with open issues.

Thanks!

Cheers,
Miguel