[PATCH V7 00/16] Rust bindings for cpufreq and OPP core + sample driver

[PATCH V7 00/16] Rust bindings for cpufreq and OPP core + sample driver

[Viresh Kumar]

Hello,

This patch series introduces initial Rust bindings for two subsystems: cpufreq
and Operating Performance Points (OPP). The bindings cover most of the
interfaces exposed by these subsystems.

Included in this series is a sample `cpufreq` driver, `rcpufreq-dt`, which is a
duplicate of the existing `cpufreq-dt` driver. The `cpufreq-dt` driver is a
generic, platform-agnostic, device-tree-based driver used on many ARM platforms.

Currently, the implementation has been tested using QEMU, verifying that
frequency transitions, various configurations, and driver binding/unbinding
functions as expected. However, performance measurements have not been
conducted.

For those interested in trying these patches, along with a few dependencies,
they can be found at:

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

This version is rebased on linux-next's master branch (needed changes from
rust-next and driver-core-next branches).

FIXME: I haven't found a solution yet for the last patch 16/16, if someone can
please help ?

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.

Thanks.

Viresh Kumar (16):
  cpufreq: Use enum for cpufreq flags that use BIT()
  PM / OPP: Add reference counting helpers for Rust implementation
  rust: cpu: Add from_cpu()
  rust: device: Add property_present()
  rust: Add cpumask helpers
  rust: Add bindings for cpumask
  rust: Add bare minimal bindings for clk framework
  rust: Add initial bindings for OPP framework
  rust: Extend OPP bindings for the OPP table
  rust: Extend OPP bindings for the configuration options
  rust: Add initial bindings for cpufreq framework
  rust: Extend cpufreq bindings for policy and driver ops
  rust: Extend cpufreq bindings for driver registration
  rust: Extend OPP bindings with CPU frequency table
  cpufreq: Add Rust based cpufreq-dt driver
  DO-NOT_MERGE: cpufreq: Rename cpufreq-dt platdev

 MAINTAINERS                          |    2 +
 drivers/cpufreq/Kconfig              |   12 +
 drivers/cpufreq/Makefile             |    1 +
 drivers/cpufreq/cpufreq-dt-platdev.c |    2 +-
 drivers/cpufreq/rcpufreq_dt.rs       |  230 ++++++
 drivers/opp/core.c                   |   17 +-
 drivers/opp/opp.h                    |    1 -
 include/linux/cpufreq.h              |   96 +--
 include/linux/pm_opp.h               |    6 +
 rust/bindings/bindings_helper.h      |    6 +
 rust/helpers/cpufreq.c               |   10 +
 rust/helpers/cpumask.c               |   35 +
 rust/helpers/helpers.c               |    2 +
 rust/kernel/clk.rs                   |   48 ++
 rust/kernel/cpu.rs                   |   26 +
 rust/kernel/cpufreq.rs               | 1056 ++++++++++++++++++++++++++
 rust/kernel/cpumask.rs               |   85 +++
 rust/kernel/device.rs                |    7 +
 rust/kernel/lib.rs                   |    7 +
 rust/kernel/opp.rs                   |  890 ++++++++++++++++++++++
 20 files changed, 2487 insertions(+), 52 deletions(-)
 create mode 100644 drivers/cpufreq/rcpufreq_dt.rs
 create mode 100644 rust/helpers/cpufreq.c
 create mode 100644 rust/helpers/cpumask.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 V7 01/16] cpufreq: Use enum for cpufreq flags that use BIT()

[Viresh Kumar]

The BIT() macro is too complex for Rust's bindgen to interpret as
integer constants. This results in many of the cpufreq macros being
undefined in Rust auto-generated bindings. By replacing the "#define"
macros with an "enum", we ensure that bindgen can properly evaluate
these values, enabling their seamless use in Rust code.

No intentional functional impact.

Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 include/linux/cpufreq.h | 96 ++++++++++++++++++++++-------------------
 1 file changed, 51 insertions(+), 45 deletions(-)

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 7fe0981a7e46..bd67728081ad 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -292,11 +292,12 @@ static inline void cpufreq_stats_record_transition(struct cpufreq_policy *policy
  *                      CPUFREQ DRIVER INTERFACE                     *
  *********************************************************************/
 
-#define CPUFREQ_RELATION_L 0  /* lowest frequency at or above target */
-#define CPUFREQ_RELATION_H 1  /* highest frequency below or at target */
-#define CPUFREQ_RELATION_C 2  /* closest frequency to target */
-/* relation flags */
-#define CPUFREQ_RELATION_E BIT(2) /* Get if possible an efficient frequency */
+enum {
+	CPUFREQ_RELATION_L = 0, /* lowest frequency at or above target */
+	CPUFREQ_RELATION_H = BIT(0), /* highest frequency below or at target */
+	CPUFREQ_RELATION_C = BIT(1), /* closest frequency to target */
+	CPUFREQ_RELATION_E = BIT(2), /* Get if possible an efficient frequency */
+};
 
 #define CPUFREQ_RELATION_LE (CPUFREQ_RELATION_L | CPUFREQ_RELATION_E)
 #define CPUFREQ_RELATION_HE (CPUFREQ_RELATION_H | CPUFREQ_RELATION_E)
@@ -418,52 +419,57 @@ struct cpufreq_driver {
 
 /* flags */
 
-/*
- * Set by drivers that need to update internal upper and lower boundaries along
- * with the target frequency and so the core and governors should also invoke
- * the diver if the target frequency does not change, but the policy min or max
- * may have changed.
- */
-#define CPUFREQ_NEED_UPDATE_LIMITS		BIT(0)
+enum {
+	/*
+	 * Set by drivers that need to update internal upper and lower
+	 * boundaries along with the target frequency and so the core and
+	 * governors should also invoke the diver if the target frequency does
+	 * not change, but the policy min or max may have changed.
+	 */
+	CPUFREQ_NEED_UPDATE_LIMITS		= BIT(0),
 
-/* loops_per_jiffy or other kernel "constants" aren't affected by frequency transitions */
-#define CPUFREQ_CONST_LOOPS			BIT(1)
+	/*
+	 * loops_per_jiffy or other kernel "constants" aren't affected by
+	 * frequency transitions.
+	 */
+	CPUFREQ_CONST_LOOPS			= BIT(1),
 
-/*
- * Set by drivers that want the core to automatically register the cpufreq
- * driver as a thermal cooling device.
- */
-#define CPUFREQ_IS_COOLING_DEV			BIT(2)
+	/*
+	 * Set by drivers that want the core to automatically register the
+	 * cpufreq driver as a thermal cooling device.
+	 */
+	CPUFREQ_IS_COOLING_DEV			= BIT(2),
 
-/*
- * This should be set by platforms having multiple clock-domains, i.e.
- * supporting multiple policies. With this sysfs directories of governor would
- * be created in cpu/cpu<num>/cpufreq/ directory and so they can use the same
- * governor with different tunables for different clusters.
- */
-#define CPUFREQ_HAVE_GOVERNOR_PER_POLICY	BIT(3)
+	/*
+	 * This should be set by platforms having multiple clock-domains, i.e.
+	 * supporting multiple policies. With this sysfs directories of governor
+	 * would be created in cpu/cpu<num>/cpufreq/ directory and so they can
+	 * use the same governor with different tunables for different clusters.
+	 */
+	CPUFREQ_HAVE_GOVERNOR_PER_POLICY	= BIT(3),
 
-/*
- * Driver will do POSTCHANGE notifications from outside of their ->target()
- * routine and so must set cpufreq_driver->flags with this flag, so that core
- * can handle them specially.
- */
-#define CPUFREQ_ASYNC_NOTIFICATION		BIT(4)
+	/*
+	 * Driver will do POSTCHANGE notifications from outside of their
+	 * ->target() routine and so must set cpufreq_driver->flags with this
+	 *  flag, so that core can handle them specially.
+	 */
+	CPUFREQ_ASYNC_NOTIFICATION		= BIT(4),
 
-/*
- * Set by drivers which want cpufreq core to check if CPU is running at a
- * frequency present in freq-table exposed by the driver. For these drivers if
- * CPU is found running at an out of table freq, we will try to set it to a freq
- * from the table. And if that fails, we will stop further boot process by
- * issuing a BUG_ON().
- */
-#define CPUFREQ_NEED_INITIAL_FREQ_CHECK	BIT(5)
+	/*
+	 * Set by drivers which want cpufreq core to check if CPU is running at
+	 * a frequency present in freq-table exposed by the driver. For these
+	 * drivers if CPU is found running at an out of table freq, we will try
+	 * to set it to a freq from the table. And if that fails, we will stop
+	 * further boot process by issuing a BUG_ON().
+	 */
+	CPUFREQ_NEED_INITIAL_FREQ_CHECK		= BIT(5),
 
-/*
- * Set by drivers to disallow use of governors with "dynamic_switching" flag
- * set.
- */
-#define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING	BIT(6)
+	/*
+	 * Set by drivers to disallow use of governors with "dynamic_switching"
+	 * flag set.
+	 */
+	CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING	= BIT(6),
+};
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
 void cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 02/16] PM / OPP: Add reference counting helpers for Rust implementation

[Viresh Kumar]

To ensure that resources such as OPP tables or OPP nodes are not freed
while in use by the Rust implementation, it is necessary to increment
their reference count from Rust code.

This commit introduces a new helper function,
dev_pm_opp_get_opp_table_ref(), to increment the reference count of an
OPP table and declares the existing helper dev_pm_opp_get() in pm_opp.h.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/opp/core.c     | 17 ++++++++++++-----
 drivers/opp/opp.h      |  1 -
 include/linux/pm_opp.h |  6 ++++++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index be3291b53719..73e9a3b2f29b 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1528,11 +1528,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
 	return ERR_PTR(ret);
 }
 
-void _get_opp_table_kref(struct opp_table *opp_table)
-{
-	kref_get(&opp_table->kref);
-}
-
 static struct opp_table *_update_opp_table_clk(struct device *dev,
 					       struct opp_table *opp_table,
 					       bool getclk)
@@ -1693,6 +1688,17 @@ static void _opp_table_kref_release(struct kref *kref)
 	kfree(opp_table);
 }
 
+void _get_opp_table_kref(struct opp_table *opp_table)
+{
+	kref_get(&opp_table->kref);
+}
+
+void dev_pm_opp_get_opp_table_ref(struct opp_table *opp_table)
+{
+	_get_opp_table_kref(opp_table);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_table_ref);
+
 void dev_pm_opp_put_opp_table(struct opp_table *opp_table)
 {
 	kref_put_mutex(&opp_table->kref, _opp_table_kref_release,
@@ -1727,6 +1733,7 @@ void dev_pm_opp_get(struct dev_pm_opp *opp)
 {
 	kref_get(&opp->kref);
 }
+EXPORT_SYMBOL_GPL(dev_pm_opp_get);
 
 void dev_pm_opp_put(struct dev_pm_opp *opp)
 {
diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 430651e7424a..5c7c81190e41 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -250,7 +250,6 @@ struct opp_table {
 };
 
 /* Routines internal to opp core */
-void dev_pm_opp_get(struct dev_pm_opp *opp);
 bool _opp_remove_all_static(struct opp_table *opp_table);
 void _get_opp_table_kref(struct opp_table *opp_table);
 int _get_opp_count(struct opp_table *opp_table);
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 414146abfe81..c247317aae38 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -100,6 +100,7 @@ struct dev_pm_opp_data {
 #if defined(CONFIG_PM_OPP)
 
 struct opp_table *dev_pm_opp_get_opp_table(struct device *dev);
+void dev_pm_opp_get_opp_table_ref(struct opp_table *opp_table);
 void dev_pm_opp_put_opp_table(struct opp_table *opp_table);
 
 unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp, bool peak, int index);
@@ -160,6 +161,7 @@ struct dev_pm_opp *dev_pm_opp_find_bw_ceil(struct device *dev,
 struct dev_pm_opp *dev_pm_opp_find_bw_floor(struct device *dev,
 					   unsigned int *bw, int index);
 
+void dev_pm_opp_get(struct dev_pm_opp *opp);
 void dev_pm_opp_put(struct dev_pm_opp *opp);
 
 int dev_pm_opp_add_dynamic(struct device *dev, struct dev_pm_opp_data *opp);
@@ -205,6 +207,8 @@ static inline struct opp_table *dev_pm_opp_get_opp_table_indexed(struct device *
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline void dev_pm_opp_get_opp_table_ref(struct opp_table *opp_table) {}
+
 static inline void dev_pm_opp_put_opp_table(struct opp_table *opp_table) {}
 
 static inline unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp, bool peak, int index)
@@ -341,6 +345,8 @@ static inline struct dev_pm_opp *dev_pm_opp_find_bw_floor(struct device *dev,
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline void dev_pm_opp_get(struct dev_pm_opp *opp) {}
+
 static inline void dev_pm_opp_put(struct dev_pm_opp *opp) {}
 
 static inline int
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 03/16] 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>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/kernel/cpu.rs              | 26 ++++++++++++++++++++++++++
 rust/kernel/lib.rs              |  1 +
 3 files changed, 28 insertions(+)
 create mode 100644 rust/kernel/cpu.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index e9fdceb568b8..d63e7f6d10ea 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/cpu.h>
 #include <linux/cred.h>
 #include <linux/errname.h>
 #include <linux/ethtool.h>
diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs
new file mode 100644
index 000000000000..422e874627d2
--- /dev/null
+++ b/rust/kernel/cpu.rs
@@ -0,0 +1,26 @@
+// 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.
+pub fn from_cpu(cpu: u32) -> Result<&'static Device> {
+    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+    // a `struct device` and is never freed by the C code.
+    let ptr = unsafe { bindings::get_cpu_device(cpu) };
+    if ptr.is_null() {
+        return Err(ENODEV);
+    }
+
+    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+    // a `struct device` and is never freed by the C code.
+    Ok(unsafe { Device::as_ref(ptr) })
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 2d5c3d7d2e21..e9106b29c359 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -39,6 +39,7 @@
 pub mod block;
 #[doc(hidden)]
 pub mod build_assert;
+pub mod cpu;
 pub mod cred;
 pub mod device;
 pub mod device_id;
-- 
2.31.1.272.g89b43f80a514

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Greg KH]

On Mon, Jan 13, 2025 at 04:52:58PM +0530, Viresh Kumar wrote:
> This implements cpu::from_cpu(), which returns a reference to
> Device for a CPU. The C struct is created at initialization time for
> CPUs and is never freed and so ARef isn't returned from this function.
> 
> The new helper will be used by Rust based cpufreq drivers.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  rust/bindings/bindings_helper.h |  1 +
>  rust/kernel/cpu.rs              | 26 ++++++++++++++++++++++++++
>  rust/kernel/lib.rs              |  1 +
>  3 files changed, 28 insertions(+)
>  create mode 100644 rust/kernel/cpu.rs
> 
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index e9fdceb568b8..d63e7f6d10ea 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/cpu.h>
>  #include <linux/cred.h>
>  #include <linux/errname.h>
>  #include <linux/ethtool.h>
> diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs
> new file mode 100644
> index 000000000000..422e874627d2
> --- /dev/null
> +++ b/rust/kernel/cpu.rs
> @@ -0,0 +1,26 @@
> +// 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.
> +pub fn from_cpu(cpu: u32) -> Result<&'static Device> {
> +    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> +    // a `struct device` and is never freed by the C code.

I thought it was pointed out that it could be freed when a cpu was
hot-unplugged?  Or is that a different device in the cpu code?  We seem
to have 2 of them and it's not obvious which is which :(

thanks,

greg k-h

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Viresh Kumar]

On 14-01-25, 19:44, Greg KH wrote:
> > +pub fn from_cpu(cpu: u32) -> Result<&'static Device> {
> > +    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> > +    // a `struct device` and is never freed by the C code.
> 
> I thought it was pointed out that it could be freed when a cpu was
> hot-unplugged?  Or is that a different device in the cpu code?  We seem
> to have 2 of them and it's not obvious which is which :(

I did reply [1] to that earlier. The CPU can get unregistered but the
memory for the device is never freed (it is part of struct cpu). Some
calls on the CPU device may fail later on (if called for an unregisted
dev), but should never crash the kernel.

-- 
viresh

[1] https://lore.kernel.org/all/20250109063605.gmykltd6bnjaspwm@vireshk-i7/

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Greg KH]

On Wed, Jan 15, 2025 at 12:50:50PM +0530, Viresh Kumar wrote:
> On 14-01-25, 19:44, Greg KH wrote:
> > > +pub fn from_cpu(cpu: u32) -> Result<&'static Device> {
> > > +    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> > > +    // a `struct device` and is never freed by the C code.
> > 
> > I thought it was pointed out that it could be freed when a cpu was
> > hot-unplugged?  Or is that a different device in the cpu code?  We seem
> > to have 2 of them and it's not obvious which is which :(
> 
> I did reply [1] to that earlier. The CPU can get unregistered but the
> memory for the device is never freed (it is part of struct cpu). Some
> calls on the CPU device may fail later on (if called for an unregisted
> dev), but should never crash the kernel.

Ah, but that's not really something that SAFETY should override, right?

Yes, you know your implementation of this will stop using the pointer in
the hotplug callback before it goes away but that's not documented here.
And having the device "fail" afterward isn't really ok either as you are
relying on the driver core to always check for this and I'm not so sure
that it always does on all codepaths.

But, I'm ok with this for now, as you are just copying the bad C model
at the moment, but it really feels like a huge foot-gun waiting to go
off.  Any way to put some more documentation here as in "use this at
your own risk!"?

thanks,

greg k-h

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Viresh Kumar]

On 15-01-25, 08:54, Greg KH wrote:
> Ah, but that's not really something that SAFETY should override, right?
> 
> Yes, you know your implementation of this will stop using the pointer in
> the hotplug callback before it goes away but that's not documented here.
> And having the device "fail" afterward isn't really ok either as you are
> relying on the driver core to always check for this and I'm not so sure
> that it always does on all codepaths.
> 
> But, I'm ok with this for now, as you are just copying the bad C model
> at the moment, but it really feels like a huge foot-gun waiting to go
> off.  Any way to put some more documentation here as in "use this at
> your own risk!"?

What about marking it unsafe ? That would require callers to document
why it is safe to call this. And yes add more documentation here too.

-- 
viresh

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Greg KH]

On Wed, Jan 15, 2025 at 01:28:59PM +0530, Viresh Kumar wrote:
> On 15-01-25, 08:54, Greg KH wrote:
> > Ah, but that's not really something that SAFETY should override, right?
> > 
> > Yes, you know your implementation of this will stop using the pointer in
> > the hotplug callback before it goes away but that's not documented here.
> > And having the device "fail" afterward isn't really ok either as you are
> > relying on the driver core to always check for this and I'm not so sure
> > that it always does on all codepaths.
> > 
> > But, I'm ok with this for now, as you are just copying the bad C model
> > at the moment, but it really feels like a huge foot-gun waiting to go
> > off.  Any way to put some more documentation here as in "use this at
> > your own risk!"?
> 
> What about marking it unsafe ? That would require callers to document
> why it is safe to call this. And yes add more documentation here too.

Sure, that's fine with me.

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Viresh Kumar]

On 15-01-25, 09:09, Greg KH wrote:
> On Wed, Jan 15, 2025 at 01:28:59PM +0530, Viresh Kumar wrote:
> > On 15-01-25, 08:54, Greg KH wrote:
> > > Ah, but that's not really something that SAFETY should override, right?
> > > 
> > > Yes, you know your implementation of this will stop using the pointer in
> > > the hotplug callback before it goes away but that's not documented here.
> > > And having the device "fail" afterward isn't really ok either as you are
> > > relying on the driver core to always check for this and I'm not so sure
> > > that it always does on all codepaths.
> > > 
> > > But, I'm ok with this for now, as you are just copying the bad C model
> > > at the moment, but it really feels like a huge foot-gun waiting to go
> > > off.  Any way to put some more documentation here as in "use this at
> > > your own risk!"?
> > 
> > What about marking it unsafe ? That would require callers to document
> > why it is safe to call this. And yes add more documentation here too.
> 
> Sure, that's fine with me.

+/// Creates a new instance of CPU's device.
+///
+/// # Safety
+///
+/// Reference counting is not implemented for the CPU device in the C code. When a CPU is
+/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory
+/// is not freed.
+///
+/// Callers must ensure that the CPU device is not used after it has been unregistered.
+/// This can be achieved, for example, by registering a CPU hotplug notifier and removing
+/// any references to the CPU device within the notifier's callback.
+pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> {
+    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+    // a `struct device` and is never freed by the C code.
+    let ptr = unsafe { bindings::get_cpu_device(cpu) };
+    if ptr.is_null() {
+        return Err(ENODEV);
+    }
+
+    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
+    // a `struct device` and is never freed by the C code.
+    Ok(unsafe { Device::as_ref(ptr) })
+}

-- 
viresh

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Alice Ryhl]

On Wed, Jan 15, 2025 at 8:54 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jan 15, 2025 at 12:50:50PM +0530, Viresh Kumar wrote:
> > On 14-01-25, 19:44, Greg KH wrote:
> > > > +pub fn from_cpu(cpu: u32) -> Result<&'static Device> {
> > > > +    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
> > > > +    // a `struct device` and is never freed by the C code.
> > >
> > > I thought it was pointed out that it could be freed when a cpu was
> > > hot-unplugged?  Or is that a different device in the cpu code?  We seem
> > > to have 2 of them and it's not obvious which is which :(
> >
> > I did reply [1] to that earlier. The CPU can get unregistered but the
> > memory for the device is never freed (it is part of struct cpu). Some
> > calls on the CPU device may fail later on (if called for an unregisted
> > dev), but should never crash the kernel.
>
> Ah, but that's not really something that SAFETY should override, right?
>
> Yes, you know your implementation of this will stop using the pointer in
> the hotplug callback before it goes away but that's not documented here.
> And having the device "fail" afterward isn't really ok either as you are
> relying on the driver core to always check for this and I'm not so sure
> that it always does on all codepaths.
>
> But, I'm ok with this for now, as you are just copying the bad C model
> at the moment, but it really feels like a huge foot-gun waiting to go
> off.  Any way to put some more documentation here as in "use this at
> your own risk!"?

On the C side, how do you normally prevent uses of the device after it
became invalid?

Alice

Re: [PATCH V7 03/16] rust: cpu: Add from_cpu()

[Viresh Kumar]

On 15-01-25, 09:10, Alice Ryhl wrote:
> On the C side, how do you normally prevent uses of the device after it
> became invalid?

IIUC, the per-cpu variable (cpu_sys_devices) that stores the pointers
to CPU devices is cleared and later calls to get_cpu_device() returns
NULL.

The hot-unplug notifiers are fired for existing users (which have
registered for the notifier, like cpufreq), wherein they can remove
per-cpu sysfs files for example.

But otherwise there is no way in the C code to disallow users of the
CPU device pointer, if it is already fetched before the CPU is
removed. The device pointer's memory doesn't get free here though and
it works.

-- 
viresh

[PATCH V7 04/16] rust: device: Add property_present()

[Viresh Kumar]

This implements Device::property_present(), which calls C APIs
device_property_present() helper.

The new helper will be used by Rust based cpufreq drivers.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/bindings/bindings_helper.h | 1 +
 rust/kernel/device.rs           | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index d63e7f6d10ea..fda1e0d8f376 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -27,6 +27,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/platform_device.h>
 #include <linux/poll.h>
+#include <linux/property.h>
 #include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/security.h>
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index d5e6a19ff6b7..e8c4cda5aacc 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -6,6 +6,7 @@
 
 use crate::{
     bindings,
+    str::CString,
     types::{ARef, Opaque},
 };
 use core::{fmt, ptr};
@@ -180,6 +181,12 @@ unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {
             )
         };
     }
+
+    /// Checks if property is present or not.
+    pub fn property_present(&self, name: &CString) -> bool {
+        // SAFETY: By the invariant of `CString`, `name` is null-terminated.
+        unsafe { bindings::device_property_present(self.as_raw().cast_const(), name.as_ptr() as *const _) }
+    }
 }
 
 // SAFETY: Instances of `Device` are always reference-counted.
-- 
2.31.1.272.g89b43f80a514

Re: [PATCH V7 04/16] rust: device: Add property_present()

[Greg Kroah-Hartman]

On Mon, Jan 13, 2025 at 04:52:59PM +0530, Viresh Kumar wrote:
> This implements Device::property_present(), which calls C APIs
> device_property_present() helper.
> 
> The new helper will be used by Rust based cpufreq drivers.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  rust/bindings/bindings_helper.h | 1 +
>  rust/kernel/device.rs           | 7 +++++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index d63e7f6d10ea..fda1e0d8f376 100644
> --- a/rust/bindings/bindings_helper.h
> +++ b/rust/bindings/bindings_helper.h
> @@ -27,6 +27,7 @@
>  #include <linux/pid_namespace.h>
>  #include <linux/platform_device.h>
>  #include <linux/poll.h>
> +#include <linux/property.h>
>  #include <linux/refcount.h>
>  #include <linux/sched.h>
>  #include <linux/security.h>
> diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
> index d5e6a19ff6b7..e8c4cda5aacc 100644
> --- a/rust/kernel/device.rs
> +++ b/rust/kernel/device.rs
> @@ -6,6 +6,7 @@
>  
>  use crate::{
>      bindings,
> +    str::CString,
>      types::{ARef, Opaque},
>  };
>  use core::{fmt, ptr};
> @@ -180,6 +181,12 @@ unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {
>              )
>          };
>      }
> +
> +    /// Checks if property is present or not.
> +    pub fn property_present(&self, name: &CString) -> bool {
> +        // SAFETY: By the invariant of `CString`, `name` is null-terminated.
> +        unsafe { bindings::device_property_present(self.as_raw().cast_const(), name.as_ptr() as *const _) }
> +    }
>  }

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH V7 04/16] rust: device: Add property_present()

[Greg Kroah-Hartman]

On Mon, Jan 13, 2025 at 04:52:59PM +0530, Viresh Kumar wrote:
> This implements Device::property_present(), which calls C APIs
> device_property_present() helper.
> 
> The new helper will be used by Rust based cpufreq drivers.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  rust/bindings/bindings_helper.h | 1 +
>  rust/kernel/device.rs           | 7 +++++++
>  2 files changed, 8 insertions(+)

Want me to take this in my driver-core tree now for 6.14-rc1?

thanks,

greg k-h

Re: [PATCH V7 04/16] rust: device: Add property_present()

[Viresh Kumar]

On 14-01-25, 19:42, Greg Kroah-Hartman wrote:
> On Mon, Jan 13, 2025 at 04:52:59PM +0530, Viresh Kumar wrote:
> > This implements Device::property_present(), which calls C APIs
> > device_property_present() helper.
> > 
> > The new helper will be used by Rust based cpufreq drivers.
> > 
> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> > ---
> >  rust/bindings/bindings_helper.h | 1 +
> >  rust/kernel/device.rs           | 7 +++++++
> >  2 files changed, 8 insertions(+)
> 
> Want me to take this in my driver-core tree now for 6.14-rc1?

Sure, Thanks.

-- 
viresh

Re: [PATCH V7 04/16] rust: device: Add property_present()

[Viresh Kumar]

+Rob/Dirk,

On 15-01-25, 12:45, Viresh Kumar wrote:
> On 14-01-25, 19:42, Greg Kroah-Hartman wrote:
> > On Mon, Jan 13, 2025 at 04:52:59PM +0530, Viresh Kumar wrote:
> > > This implements Device::property_present(), which calls C APIs
> > > device_property_present() helper.
> > > 
> > > The new helper will be used by Rust based cpufreq drivers.
> > > 
> > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> > > ---
> > >  rust/bindings/bindings_helper.h | 1 +
> > >  rust/kernel/device.rs           | 7 +++++++
> > >  2 files changed, 8 insertions(+)
> > 
> > Want me to take this in my driver-core tree now for 6.14-rc1?
> 
> Sure, Thanks.

I now see that Rob/Dirk have sent [1] a bigger patch earlier which adds
this functionality along with other DT bindings. Though it isn't
merged yet.

-- 
viresh

[1] https://lore.kernel.org/all/20241122081257.1776925-1-dirk.behme@de.bosch.com/

Re: [PATCH V7 04/16] rust: device: Add property_present()

[Greg Kroah-Hartman]

On Wed, Jan 15, 2025 at 01:05:15PM +0530, Viresh Kumar wrote:
> +Rob/Dirk,
> 
> On 15-01-25, 12:45, Viresh Kumar wrote:
> > On 14-01-25, 19:42, Greg Kroah-Hartman wrote:
> > > On Mon, Jan 13, 2025 at 04:52:59PM +0530, Viresh Kumar wrote:
> > > > This implements Device::property_present(), which calls C APIs
> > > > device_property_present() helper.
> > > > 
> > > > The new helper will be used by Rust based cpufreq drivers.
> > > > 
> > > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> > > > ---
> > > >  rust/bindings/bindings_helper.h | 1 +
> > > >  rust/kernel/device.rs           | 7 +++++++
> > > >  2 files changed, 8 insertions(+)
> > > 
> > > Want me to take this in my driver-core tree now for 6.14-rc1?
> > 
> > Sure, Thanks.
> 
> I now see that Rob/Dirk have sent [1] a bigger patch earlier which adds
> this functionality along with other DT bindings. Though it isn't
> merged yet.

That's still in the RFC stage, I'll take this now so that when the RFC
patchset is rebased/resubmitted, it will be smaller.

thanks,

greg k-h

[PATCH V7 05/16] rust: Add cpumask helpers

[Viresh Kumar]

In order to prepare for adding Rust abstractions for cpumask, this patch
adds cpumask helpers.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/helpers/cpumask.c          | 35 +++++++++++++++++++++++++++++++++
 rust/helpers/helpers.c          |  1 +
 3 files changed, 37 insertions(+)
 create mode 100644 rust/helpers/cpumask.c

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index fda1e0d8f376..59b4bc49d039 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/cpu.h>
+#include <linux/cpumask.h>
 #include <linux/cred.h>
 #include <linux/errname.h>
 #include <linux/ethtool.h>
diff --git a/rust/helpers/cpumask.c b/rust/helpers/cpumask.c
new file mode 100644
index 000000000000..0b371826a13c
--- /dev/null
+++ b/rust/helpers/cpumask.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/cpumask.h>
+
+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_setall(struct cpumask *dstp)
+{
+	cpumask_setall(dstp);
+}
+
+void rust_helper_cpumask_copy(struct cpumask *dstp, const struct cpumask *srcp)
+{
+	cpumask_copy(dstp, srcp);
+}
+
+bool rust_helper_zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+	return zalloc_cpumask_var(mask, flags);
+}
+
+#ifndef CONFIG_CPUMASK_OFFSTACK
+void rust_helper_free_cpumask_var(cpumask_var_t mask)
+{
+	free_cpumask_var(mask);
+}
+#endif
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 0640b7e115be..de2341cfd917 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 "cpumask.c"
 #include "cred.c"
 #include "device.c"
 #include "err.c"
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 06/16] rust: Add bindings for cpumask

[Viresh Kumar]

This patch adds basic Rust bindings for struct cpumask.

These will be used by Rust based cpufreq / OPP core.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/cpumask.rs | 85 ++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs     |  1 +
 2 files changed, 86 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..e3b15bc12798
--- /dev/null
+++ b/rust/kernel/cpumask.rs
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! CPU mask abstractions.
+//!
+//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h)
+
+use crate::{bindings, error::Result, prelude::ENOMEM};
+use core::ptr;
+
+/// A simple implementation of `struct cpumask` from the C code.
+pub struct Cpumask {
+    ptr: *mut bindings::cpumask,
+    owned: bool,
+}
+
+impl Cpumask {
+    /// Creates empty cpumask.
+    pub fn new() -> Result<Self> {
+        let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+        // SAFETY: Depending on the value of `gfp_flags`, this call may sleep. Other than that, it
+        // is always safe to call this method.
+        if !unsafe { bindings::zalloc_cpumask_var(&mut ptr, bindings::GFP_KERNEL) } {
+            return Err(ENOMEM);
+        }
+
+        Ok(Self { ptr, owned: true })
+    }
+
+    /// Creates a new abstraction instance of an existing `struct cpumask` pointer.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `ptr` is valid, and non-null.
+    pub unsafe fn get_cpumask(ptr: *mut bindings::cpumask) -> Self {
+        Self { ptr, owned: false }
+    }
+
+    /// Obtain the raw `struct cpumask *`.
+    pub fn as_raw(&mut self) -> *mut bindings::cpumask {
+        self.ptr
+    }
+
+    /// Sets CPU in the cpumask.
+    ///
+    /// Update the cpumask with a single CPU.
+    pub fn set(&mut self, cpu: u32) {
+        // SAFETY: `ptr` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+        // call `cpumask_set_cpus()` for any CPU.
+        unsafe { bindings::cpumask_set_cpu(cpu, self.ptr) };
+    }
+
+    /// Clears CPU in the cpumask.
+    ///
+    /// Update the cpumask with a single CPU.
+    pub fn clear(&mut self, cpu: i32) {
+        // SAFETY: `ptr` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+        // call `cpumask_clear_cpu()` for any CPU.
+        unsafe { bindings::cpumask_clear_cpu(cpu, self.ptr) };
+    }
+
+    /// Sets all CPUs in the cpumask.
+    pub fn set_all(&mut self) {
+        // SAFETY: `ptr` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+        // call `cpumask_setall()`.
+        unsafe { bindings::cpumask_setall(self.ptr) };
+    }
+
+    /// Copies cpumask.
+    pub fn copy(&self, dstp: &mut Self) {
+        // SAFETY: `ptr` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+        // call `cpumask_copy()`.
+        unsafe { bindings::cpumask_copy(dstp.as_raw(), self.ptr) };
+    }
+}
+
+impl Drop for Cpumask {
+    fn drop(&mut self) {
+        if self.owned {
+            // SAFETY: `ptr` is guaranteed to be valid for the lifetime of `self`. And it is safe
+            // to call `free_cpumask_var()`.
+            unsafe { bindings::free_cpumask_var(self.ptr) }
+        }
+    }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index e9106b29c359..2f72e1d8a6b7 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -40,6 +40,7 @@
 #[doc(hidden)]
 pub mod build_assert;
 pub mod cpu;
+pub mod cpumask;
 pub mod cred;
 pub mod device;
 pub mod device_id;
-- 
2.31.1.272.g89b43f80a514

Re: [PATCH V7 06/16] rust: Add bindings for cpumask

[Miguel Ojeda]

On Mon, Jan 13, 2025 at 12:23 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
>  rust/kernel/cpumask.rs | 85 ++++++++++++++++++++++++++++++++++++++++++

BITMAP API maintains `cpumask` on the C side -- Cc'ing them, since
they didn't seem to be in the loop?

Relatedly, should this have a `MAINTAINERS` entry?

Thanks!

Cheers,
Miguel

Re: [PATCH V7 06/16] rust: Add bindings for cpumask

[Viresh Kumar]

On 22-01-25, 15:40, Miguel Ojeda wrote:
> On Mon, Jan 13, 2025 at 12:23 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> >  rust/kernel/cpumask.rs | 85 ++++++++++++++++++++++++++++++++++++++++++
> 
> BITMAP API maintains `cpumask` on the C side -- Cc'ing them, since
> they didn't seem to be in the loop?
> 
> Relatedly, should this have a `MAINTAINERS` entry?

Updated MAINTAINERS for this and clk bindings now. Will be part of V8.

-- 
viresh

[PATCH V7 07/16] rust: Add bare minimal bindings for clk framework

[Viresh Kumar]

This adds very basic bindings for the clk framework, implements only
clk_get() and clk_put(). These are the bare minimum bindings required
for many users and are simple enough to add in the first attempt.

These will be used by Rust based cpufreq / OPP core to begin with.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/kernel/clk.rs              | 48 +++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |  1 +
 3 files changed, 50 insertions(+)
 create mode 100644 rust/kernel/clk.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 59b4bc49d039..4eadcf645df0 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/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/cred.h>
diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
new file mode 100644
index 000000000000..123cdb43b115
--- /dev/null
+++ b/rust/kernel/clk.rs
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Clock abstractions.
+//!
+//! C header: [`include/linux/clk.h`](srctree/include/linux/clk.h)
+
+use crate::{
+    bindings,
+    device::Device,
+    error::{from_err_ptr, Result},
+    prelude::*,
+};
+
+use core::ptr;
+
+/// A simple implementation of `struct clk` from the C code.
+#[repr(transparent)]
+pub struct Clk(*mut bindings::clk);
+
+impl Clk {
+    /// Creates `Clk` instance for a device and a connection id.
+    pub fn new(dev: &Device, name: Option<&CStr>) -> Result<Self> {
+        let con_id = if let Some(name) = name {
+            name.as_ptr() as *const _
+        } else {
+            ptr::null()
+        };
+
+        // SAFETY: It is safe to call `clk_get()`, on a device pointer earlier received from the C
+        // code.
+        Ok(Self(from_err_ptr(unsafe {
+            bindings::clk_get(dev.as_raw(), con_id)
+        })?))
+    }
+
+    /// Obtain the raw `struct clk *`.
+    pub fn as_raw(&self) -> *mut bindings::clk {
+        self.0
+    }
+}
+
+impl Drop for Clk {
+    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::clk_put(self.0) };
+    }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 2f72e1d8a6b7..5d43dc5ec9eb 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -39,6 +39,7 @@
 pub mod block;
 #[doc(hidden)]
 pub mod build_assert;
+pub mod clk;
 pub mod cpu;
 pub mod cpumask;
 pub mod cred;
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 08/16] rust: Add initial bindings for OPP framework

[Viresh Kumar]

This commit adds initial Rust bindings for the Operating performance
points (OPP) core. This adds bindings for struct dev_pm_opp and
struct dev_pm_opp_data to begin with.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
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              | 189 ++++++++++++++++++++++++++++++++
 4 files changed, 193 insertions(+)
 create mode 100644 rust/kernel/opp.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index 8ee1c013cd6e..3f9ebca78732 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17707,6 +17707,7 @@ 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 4eadcf645df0..7f851d5907af 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -28,6 +28,7 @@
 #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 5d43dc5ec9eb..d1c0f136952e 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -62,6 +62,8 @@
 #[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..becb33880c92
--- /dev/null
+++ b/rust/kernel/opp.rs
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Operating performance points.
+//!
+//! This module provides bindings for interacting with the OPP subsystem.
+//!
+//! C header: [`include/linux/pm_opp.h`](srctree/include/linux/pm_opp.h)
+
+use crate::{
+    bindings,
+    device::Device,
+    error::{code::*, to_result, Result},
+    types::{ARef, AlwaysRefCounted, Opaque},
+};
+
+use core::ptr;
+
+/// Dynamically created Operating performance point (OPP).
+pub struct Token {
+    dev: ARef<Device>,
+    freq: usize,
+}
+
+impl Token {
+    /// Adds an OPP dynamically.
+    pub 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) };
+    }
+}
+
+/// Equivalent to `struct dev_pm_opp_data` in the C Code.
+#[repr(transparent)]
+pub struct Data(bindings::dev_pm_opp_data);
+
+impl Data {
+    /// Creates new instance of [`Data`].
+    pub fn new(freq: usize, u_volt: usize, level: u32, turbo: bool) -> Self {
+        Self(bindings::dev_pm_opp_data {
+            turbo,
+            freq,
+            u_volt,
+            level,
+        })
+    }
+
+    /// Adds an OPP dynamically. The OPP is freed once the [`Token`] gets freed.
+    pub fn add_opp(self, dev: &ARef<Device>) -> Result<Token> {
+        Token::new(dev, self)
+    }
+
+    fn freq(&self) -> usize {
+        self.0.freq
+    }
+}
+
+/// Operating performance point (OPP).
+///
+/// Wraps the kernel's `struct dev_pm_opp`.
+///
+/// The pointer to `struct dev_pm_opp` is non-null and valid for the lifetime of the `OPP`
+/// instance.
+///
+/// # Invariants
+///
+/// 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's OK to send the ownership of `OPP` across thread boundaries.
+unsafe impl Send for OPP {}
+
+// SAFETY: It's OK 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 OPP's refcount 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.
+        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.
+    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>) -> usize {
+        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.
+        unsafe { bindings::dev_pm_opp_get_freq_indexed(self.as_raw(), index) }
+    }
+
+    /// Returns the voltage of an OPP.
+    pub fn voltage(&self) -> usize {
+        // 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_voltage(self.as_raw()) }
+    }
+
+    /// Returns the level of an OPP.
+    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.
+    pub fn power(&self) -> usize {
+        // 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_power(self.as_raw()) }
+    }
+
+    /// Returns the required pstate of an OPP.
+    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.
+    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 V7 09/16] rust: Extend OPP bindings for the OPP table

[Viresh Kumar]

This extends OPP bindings with the bindings for the struct opp_table.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/opp.rs | 383 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 382 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index becb33880c92..d3b98d9a554e 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -8,8 +8,9 @@
 
 use crate::{
     bindings,
+    cpumask::Cpumask,
     device::Device,
-    error::{code::*, to_result, Result},
+    error::{code::*, from_err_ptr, to_result, Error, Result},
     types::{ARef, AlwaysRefCounted, Opaque},
 };
 
@@ -67,6 +68,386 @@ fn freq(&self) -> usize {
     }
 }
 
+/// OPP search types.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum SearchType {
+    /// Search for exact value.
+    Exact,
+    /// Search for highest value less than equal to value.
+    Floor,
+    /// Search for lowest value greater than equal to value.
+    Ceil,
+}
+
+/// Operating performance point (OPP) table.
+///
+/// Wraps the kernel's `struct opp_table`.
+///
+/// The pointer stored in `Self` is non-null and valid for the lifetime of the `Table`.
+pub struct Table {
+    ptr: *mut bindings::opp_table,
+    dev: ARef<Device>,
+    em: bool,
+    of: bool,
+    cpumask: Option<Cpumask>,
+}
+
+// SAFETY: It is okay to send ownership of `Table` across thread boundaries.
+unsafe impl Send for Table {}
+
+// SAFETY: It's OK 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 OPP table instance from 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.
+        unsafe { bindings::dev_pm_opp_get_opp_table_ref(ptr) };
+
+        Self {
+            ptr,
+            dev: dev.clone(),
+            em: false,
+            of: false,
+            cpumask: None,
+        }
+    }
+
+    /// Find OPP table from device.
+    pub fn from_dev(dev: &Device) -> Result<Self> {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements. Refcount of the OPP table is incremented by the C code.
+        let ptr = from_err_ptr(unsafe { bindings::dev_pm_opp_get_opp_table(dev.as_raw()) })?;
+
+        Ok(Self {
+            ptr,
+            dev: dev.into(),
+            em: false,
+            of: false,
+            cpumask: None,
+        })
+    }
+
+    /// Add device tree based OPP table for the device.
+    #[cfg(CONFIG_OF)]
+    pub fn from_of(dev: &ARef<Device>, index: i32) -> Result<Self> {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements. Refcount of the OPP table is incremented by the C code.
+        to_result(unsafe { bindings::dev_pm_opp_of_add_table_indexed(dev.as_raw(), index) })?;
+
+        // Fetch the newly created table.
+        let mut table = Self::from_dev(dev)?;
+        table.of = true;
+
+        Ok(table)
+    }
+
+    // Remove device tree based OPP table for the device.
+    #[cfg(CONFIG_OF)]
+    fn remove_of(&self) {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements. We took the reference earlier from `from_of` earlier, it is safe to drop
+        // the same now.
+        unsafe { bindings::dev_pm_opp_of_remove_table(self.dev.as_raw()) };
+    }
+
+    /// Add device tree based OPP table for CPU devices.
+    #[cfg(CONFIG_OF)]
+    pub fn from_of_cpumask(dev: &Device, cpumask: &mut Cpumask) -> Result<Self> {
+        // SAFETY: The cpumask is valid and the returned ptr will be owned by the [`Table`] instance.
+        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)?;
+
+        let mut mask = Cpumask::new()?;
+        cpumask.copy(&mut mask);
+        table.cpumask = Some(mask);
+
+        Ok(table)
+    }
+
+    // Remove device tree based OPP table for CPU devices.
+    #[cfg(CONFIG_OF)]
+    fn remove_of_cpumask(&self, mut 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 OPPs 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 of the OPPs in the table.
+    pub fn max_clock_latency(&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 of the OPPs in the table.
+    pub fn max_volt_latency(&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 of the OPPs in the table.
+    pub fn max_transition_latency(&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.
+    pub fn suspend_freq(&self) -> usize {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements.
+        unsafe { bindings::dev_pm_opp_get_suspend_opp_freq(self.dev.as_raw()) }
+    }
+
+    /// Synchronizes regulators used by the OPP table.
+    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.
+    pub fn sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result<()> {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements.
+        to_result(unsafe {
+            bindings::dev_pm_opp_get_sharing_cpus(dev.as_raw(), cpumask.as_raw())
+        })
+    }
+
+    /// Sets sharing CPUs.
+    pub fn set_sharing_cpus(&mut self, cpumask: &mut Cpumask) -> Result<()> {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements.
+        to_result(unsafe {
+            bindings::dev_pm_opp_set_sharing_cpus(self.dev.as_raw(), cpumask.as_raw())
+        })?;
+
+        if let Some(mask) = self.cpumask.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)]
+    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.
+    pub fn adjust_voltage(
+        &self,
+        freq: usize,
+        u_volt: usize,
+        u_volt_min: usize,
+        u_volt_max: usize,
+    ) -> 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,
+                u_volt,
+                u_volt_min,
+                u_volt_max,
+            )
+        })
+    }
+
+    /// Sets a matching OPP based on frequency.
+    pub fn set_rate(&self, freq: usize) -> 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) })
+    }
+
+    /// Sets exact OPP.
+    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,
+        mut freq: usize,
+        available: Option<bool>,
+        index: Option<u32>,
+        stype: SearchType,
+    ) -> Result<ARef<OPP>> {
+        let rdev = self.dev.as_raw();
+        let index = index.unwrap_or(0);
+
+        let ptr = from_err_ptr(match stype {
+            SearchType::Exact => {
+                if let Some(available) = available {
+                    // SAFETY: The requirements are satisfied by the existence of `Device` and
+                    // its safety requirements. The returned ptr will be owned by the new [`OPP`]
+                    // instance.
+                    unsafe {
+                        bindings::dev_pm_opp_find_freq_exact_indexed(rdev, freq, index, available)
+                    }
+                } else {
+                    return Err(EINVAL);
+                }
+            }
+
+            // SAFETY: The requirements are satisfied by the existence of `Device` and its
+            // safety requirements. The returned ptr will be owned by the new [`OPP`] instance.
+            SearchType::Ceil => unsafe {
+                bindings::dev_pm_opp_find_freq_ceil_indexed(rdev, &mut freq as *mut usize, index)
+            },
+
+            // SAFETY: The requirements are satisfied by the existence of `Device` and its
+            // safety requirements. The returned ptr will be owned by the new [`OPP`] instance.
+            SearchType::Floor => unsafe {
+                bindings::dev_pm_opp_find_freq_floor_indexed(rdev, &mut freq as *mut usize, index)
+            },
+        })?;
+
+        // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+        unsafe { OPP::from_raw_opp_owned(ptr) }
+    }
+
+    /// Finds OPP based on level.
+    pub fn opp_from_level(&self, mut level: u32, stype: SearchType) -> Result<ARef<OPP>> {
+        let rdev = 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 ptr will be owned by the new [`OPP`] instance.
+            SearchType::Exact => unsafe { bindings::dev_pm_opp_find_level_exact(rdev, level) },
+
+            // SAFETY: The requirements are satisfied by the existence of `Device` and its
+            // safety requirements. The returned ptr will be owned by the new [`OPP`] instance.
+            SearchType::Ceil => unsafe {
+                bindings::dev_pm_opp_find_level_ceil(rdev, &mut level as *mut u32)
+            },
+
+            // SAFETY: The requirements are satisfied by the existence of `Device` and its
+            // safety requirements. The returned ptr will be owned by the new [`OPP`] instance.
+            SearchType::Floor => unsafe {
+                bindings::dev_pm_opp_find_level_floor(rdev, &mut level as *mut u32)
+            },
+        })?;
+
+        // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+        unsafe { OPP::from_raw_opp_owned(ptr) }
+    }
+
+    /// Finds OPP based on bandwidth.
+    pub fn opp_from_bw(&self, mut bw: u32, index: i32, stype: SearchType) -> Result<ARef<OPP>> {
+        let rdev = 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 ptr will be owned by the new [`OPP`] instance.
+            SearchType::Ceil => unsafe {
+                bindings::dev_pm_opp_find_bw_ceil(rdev, &mut bw as *mut u32, index)
+            },
+
+            // SAFETY: The requirements are satisfied by the existence of `Device` and its
+            // safety requirements. The returned ptr will be owned by the new [`OPP`] instance.
+            SearchType::Floor => unsafe {
+                bindings::dev_pm_opp_find_bw_floor(rdev, &mut bw as *mut u32, index)
+            },
+        })?;
+
+        // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+        unsafe { OPP::from_raw_opp_owned(ptr) }
+    }
+
+    /// Enable the OPP.
+    pub fn enable_opp(&self, freq: usize) -> 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) })
+    }
+
+    /// Disable the OPP.
+    pub fn disable_opp(&self, freq: usize) -> 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) })
+    }
+
+    /// Registers with Energy model.
+    #[cfg(CONFIG_OF)]
+    pub fn of_register_em(&mut self, cpumask: &mut Cpumask) -> Result<()> {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements.
+        to_result(unsafe {
+            bindings::dev_pm_opp_of_register_em(self.dev.as_raw(), cpumask.as_raw())
+        })?;
+
+        self.em = true;
+        Ok(())
+    }
+
+    // Unregisters with Energy model.
+    #[cfg(all(CONFIG_OF, CONFIG_ENERGY_MODEL))]
+    fn of_unregister_em(&self) {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements. We registered with the EM framework earlier, it is safe to unregister now.
+        unsafe { bindings::em_dev_unregister_perf_domain(self.dev.as_raw()) };
+    }
+}
+
+impl Drop for Table {
+    fn drop(&mut self) {
+        // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe
+        // to relinquish it now.
+        unsafe { bindings::dev_pm_opp_put_opp_table(self.ptr) };
+
+        #[cfg(CONFIG_OF)]
+        {
+            #[cfg(CONFIG_ENERGY_MODEL)]
+            if self.em {
+                self.of_unregister_em();
+            }
+
+            if self.of {
+                self.remove_of();
+            } else if let Some(cpumask) = self.cpumask.take() {
+                self.remove_of_cpumask(cpumask);
+            }
+        }
+    }
+}
+
 /// Operating performance point (OPP).
 ///
 /// Wraps the kernel's `struct dev_pm_opp`.
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 10/16] rust: Extend OPP bindings for the configuration options

[Viresh Kumar]

This extends OPP bindings with the bindings for the OPP core
configuration options.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/opp.rs | 262 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 260 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index d3b98d9a554e..22c4d543f456 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -10,11 +10,28 @@
     bindings,
     cpumask::Cpumask,
     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},
+    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 Cstrings.
+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)
+}
 
 /// Dynamically created Operating performance point (OPP).
 pub struct Token {
@@ -79,6 +96,247 @@ pub enum SearchType {
     Ceil,
 }
 
+/// Implement this trait to provide OPP Configuration callbacks.
+#[vtable]
+pub trait ConfigOps {
+    /// Called by the OPP core to configure OPP clks.
+    fn config_clks(_dev: &Device, _table: &Table, _opp: &OPP, _scaling_down: bool) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Called by the OPP core to configure OPP regulators.
+    fn config_regulators(
+        _dev: &Device,
+        _opp_old: &OPP,
+        _opp_new: &OPP,
+        _data: *mut *mut bindings::regulator,
+        _count: u32,
+    ) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+}
+
+/// Config token returned by the C code.
+pub struct ConfigToken(i32);
+
+impl Drop for ConfigToken {
+    fn drop(&mut self) {
+        // SAFETY: Its safe to return the configuration token number previously received from the C
+        // code.
+        unsafe { bindings::dev_pm_opp_clear_config(self.0) };
+    }
+}
+
+/// Equivalent to `struct dev_pm_opp_config` in the C Code.
+#[derive(Default)]
+pub struct Config<T: ConfigOps> {
+    clk_names: Option<KVec<CString>>,
+    prop_name: Option<CString>,
+    regulator_names: Option<KVec<CString>>,
+    supported_hw: Option<KVec<u32>>,
+    required_dev: Option<ARef<Device>>,
+    required_dev_index: Option<u32>,
+    _data: PhantomData<T>,
+}
+
+impl<T: ConfigOps> Config<T> {
+    /// Creates a new instance of [`Config`].
+    pub fn new() -> Self {
+        Self {
+            clk_names: None,
+            prop_name: None,
+            regulator_names: None,
+            supported_hw: None,
+            required_dev: None,
+            required_dev_index: None,
+            _data: PhantomData,
+        }
+    }
+
+    /// Initializes clock names.
+    pub fn set_clk_names(mut self, names: KVec<CString>) -> Result<Self> {
+        // Already configured.
+        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> {
+        // Already configured.
+        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> {
+        // Already configured.
+        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> {
+        // Already configured.
+        if self.required_dev.is_some() {
+            return Err(EBUSY);
+        }
+
+        self.required_dev = Some(dev);
+        self.required_dev_index = Some(index);
+        Ok(self)
+    }
+
+    /// Initializes supported hardware.
+    pub fn set_supported_hw(mut self, hw: KVec<u32>) -> Result<Self> {
+        // Already configured.
+        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.
+    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 = match &self.prop_name {
+            Some(x) => x.as_char_ptr(),
+            None => ptr::null(),
+        };
+
+        let (supported_hw, supported_hw_count) = match &self.supported_hw {
+            Some(x) => (x.as_ptr(), x.len() as u32),
+            None => (ptr::null(), 0),
+        };
+
+        let (required_dev, required_dev_index) = match &self.required_dev {
+            Some(x) => (x.as_raw(), self.required_dev_index.unwrap()),
+            None => (ptr::null_mut(), 0),
+        };
+
+        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 to not use fields of `config`, after this call has
+        // returned 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 config_clks callback.
+    extern "C" fn config_clks(
+        dev: *mut bindings::device,
+        opp_table: *mut bindings::opp_table,
+        opp: *mut bindings::dev_pm_opp,
+        _data: *mut core::ffi::c_void,
+        scaling_down: bool,
+    ) -> core::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 config_regulators callback.
+    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: core::ffi::c_uint,
+    ) -> core::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)
+        })
+    }
+}
+
 /// Operating performance point (OPP) table.
 ///
 /// Wraps the kernel's `struct opp_table`.
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 11/16] rust: Add initial bindings for cpufreq framework

[Viresh Kumar]

This commit adds initial Rust bindings for the cpufreq core. This adds
basic bindings for cpufreq flags, relations and cpufreq table.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
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          | 231 ++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |   2 +
 6 files changed, 246 insertions(+)
 create mode 100644 rust/helpers/cpufreq.c
 create mode 100644 rust/kernel/cpufreq.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index 3f9ebca78732..fb92356efbba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6017,6 +6017,7 @@ 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 7f851d5907af..68bf1bc5bae8 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/errname.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 de2341cfd917..32d0462219e5 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 "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..3dfdf5ccb9b8
--- /dev/null
+++ b/rust/kernel/cpufreq.rs
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! CPU frequency scaling.
+//!
+//! This module provides bindings for interacting with the cpufreq subsystem.
+//!
+//! C header: [`include/linux/cpufreq.h`](srctree/include/linux/cpufreq.h)
+
+use crate::{
+    bindings,
+    error::{code::*, to_result, Result},
+    prelude::*,
+};
+
+use core::{
+    pin::Pin,
+};
+
+/// Default transition latency value.
+pub const ETERNAL_LATENCY: u32 = bindings::CPUFREQ_ETERNAL as u32;
+
+/// Container for cpufreq driver flags.
+pub mod flags {
+    use crate::bindings;
+
+    /// Set by drivers that need to update internal upper and lower boundaries along with the
+    /// target frequency and so the core and governors should also invoke the driver if the target
+    /// frequency does not change, but the policy min or max may have changed.
+    pub const NEED_UPDATE_LIMITS: u16 = bindings::CPUFREQ_NEED_UPDATE_LIMITS as _;
+
+    /// Set by drivers for platforms where loops_per_jiffy or other kernel "constants" aren't
+    /// affected by frequency transitions.
+    pub const CONST_LOOPS: u16 = bindings::CPUFREQ_CONST_LOOPS as _;
+
+    /// Set by drivers that want the core to automatically register the cpufreq driver as a thermal
+    /// cooling device.
+    pub const IS_COOLING_DEV: u16 = bindings::CPUFREQ_IS_COOLING_DEV as _;
+
+    /// Set by drivers for platforms that have multiple clock-domains, i.e. supporting multiple
+    /// policies. With this sysfs directories of governor would be created in cpu/cpuN/cpufreq/
+    /// directory and so they can use the same governor with different tunables for different
+    /// clusters.
+    pub const HAVE_GOVERNOR_PER_POLICY: u16 = bindings::CPUFREQ_HAVE_GOVERNOR_PER_POLICY as _;
+
+    /// Set by drivers which do POSTCHANGE notifications from outside of their ->target() routine.
+    pub const ASYNC_NOTIFICATION: u16 = bindings::CPUFREQ_ASYNC_NOTIFICATION as _;
+
+    /// Set by drivers that want cpufreq core to check if CPU is running at a frequency present in
+    /// freq-table exposed by the driver. For these drivers if CPU is found running at an out of
+    /// table freq, the cpufreq core will try to change the frequency to a value from the table.
+    /// And if that fails, it will stop further boot process by issuing a BUG_ON().
+    pub const NEED_INITIAL_FREQ_CHECK: u16 = bindings::CPUFREQ_NEED_INITIAL_FREQ_CHECK as _;
+
+    /// Set by drivers to disallow use of governors with "dynamic_switching" flag set.
+    pub const NO_AUTO_DYNAMIC_SWITCHING: u16 = bindings::CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING as _;
+}
+
+/// CPU frequency selection relations. Each value contains a `bool` argument which corresponds to
+/// the Relation being 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 {
+    // Converts from a value compatible with the C code.
+    fn new(val: u32) -> Result<Self> {
+        let efficient = val & bindings::CPUFREQ_RELATION_E != 0;
+
+        Ok(match val & !bindings::CPUFREQ_RELATION_E {
+            bindings::CPUFREQ_RELATION_L => Self::Low(efficient),
+            bindings::CPUFREQ_RELATION_H => Self::High(efficient),
+            bindings::CPUFREQ_RELATION_C => Self::Close(efficient),
+            _ => return Err(EINVAL),
+        })
+    }
+
+    /// Converts to a value compatible with the C code.
+    pub fn val(&self) -> u32 {
+        let (mut val, e) = match self {
+            Self::Low(e) => (bindings::CPUFREQ_RELATION_L, e),
+            Self::High(e) => (bindings::CPUFREQ_RELATION_H, e),
+            Self::Close(e) => (bindings::CPUFREQ_RELATION_C, e),
+        };
+
+        if *e {
+            val |= bindings::CPUFREQ_RELATION_E;
+        }
+
+        val
+    }
+}
+
+/// Equivalent to `struct cpufreq_policy_data` in the C code.
+#[repr(transparent)]
+pub struct PolicyData(*mut bindings::cpufreq_policy_data);
+
+impl PolicyData {
+    /// Creates new instance of [`PolicyData`].
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `ptr` is valid and non-null.
+    pub unsafe fn from_raw_policy_data(ptr: *mut bindings::cpufreq_policy_data) -> Self {
+        Self(ptr)
+    }
+
+    /// Returns the raw pointer to the C structure.
+    #[inline]
+    pub fn as_raw(&self) -> *mut bindings::cpufreq_policy_data {
+        self.0
+    }
+
+    /// Provides a wrapper to the generic verify routine.
+    pub fn generic_verify(&self) -> Result<()> {
+        // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+        // use it now.
+        to_result(unsafe { bindings::cpufreq_generic_frequency_table_verify(self.as_raw()) })
+    }
+}
+
+/// Builder for the `struct cpufreq_frequency_table` in the C code.
+#[repr(transparent)]
+#[derive(Default)]
+pub struct TableBuilder {
+    entries: KVec<bindings::cpufreq_frequency_table>,
+}
+
+impl TableBuilder {
+    /// Creates new instance of [`TableBuilder`].
+    pub fn new() -> Self {
+        Self {
+            entries: KVec::new(),
+        }
+    }
+
+    /// Adds a new entry to the table.
+    pub fn add(&mut self, frequency: u32, flags: u32, driver_data: u32) -> Result<()> {
+        // Adds new entry to the end of the vector.
+        Ok(self.entries.push(
+            bindings::cpufreq_frequency_table {
+                flags,
+                driver_data,
+                frequency,
+            },
+            GFP_KERNEL,
+        )?)
+    }
+
+    /// Creates [`Table`] from [`TableBuilder`].
+    pub fn into_table(mut self) -> Result<Table> {
+        // Add last entry to the table.
+        self.add(bindings::CPUFREQ_TABLE_END as u32, 0, 0)?;
+        Table::from_builder(self.entries)
+    }
+}
+
+/// A simple implementation of the cpufreq table, equivalent to the `struct
+/// cpufreq_frequency_table` in the C code.
+pub struct Table {
+    #[allow(dead_code)]
+    // Dynamically created table.
+    entries: Option<Pin<KVec<bindings::cpufreq_frequency_table>>>,
+
+    // Pointer to the statically or dynamically created table.
+    ptr: *mut bindings::cpufreq_frequency_table,
+}
+
+impl Table {
+    /// Creates new instance of [`Table`] from [`TableBuilder`].
+    fn from_builder(entries: KVec<bindings::cpufreq_frequency_table>) -> Result<Self> {
+        if entries.is_empty() {
+            return Err(EINVAL);
+        }
+
+        // Pin the entries to memory, since we are passing its pointer to the C code.
+        let mut entries = Pin::new(entries);
+
+        // The pointer is valid until the table gets dropped.
+        let ptr = entries.as_mut_ptr();
+
+        Ok(Self {
+            entries: Some(entries),
+            ptr,
+        })
+    }
+
+    /// Creates new instance of [`Table`] from raw pointer.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `ptr` is valid and non-null for the lifetime of the [`Table`].
+    pub unsafe fn from_raw(ptr: *mut bindings::cpufreq_frequency_table) -> Self {
+        Self {
+            entries: None,
+            ptr,
+        }
+    }
+
+    /// Returns raw pointer to the `struct cpufreq_frequency_table` compatible with the C code.
+    #[inline]
+    pub fn as_raw(&self) -> *mut bindings::cpufreq_frequency_table {
+        self.ptr
+    }
+
+    /// Returns `frequency` at index in the [`Table`].
+    pub fn freq(&self, index: usize) -> Result<u32> {
+        // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is
+        // guaranteed to be within limits of the frequency table by the C API.
+        Ok(unsafe { (*self.ptr.add(index)).frequency })
+    }
+
+    /// Returns `flags` at index in the [`Table`].
+    pub fn flags(&self, index: usize) -> Result<u32> {
+        // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is
+        // guaranteed to be within limits of the frequency table by the C API.
+        Ok(unsafe { (*self.ptr.add(index)).flags })
+    }
+
+    /// Returns `data` at index in the [`Table`].
+    pub fn data(&self, index: usize) -> Result<u32> {
+        // SAFETY: The pointer is guaranteed to be valid for the lifetime of `self` and `index` is
+        // guaranteed to be within limits of the frequency table by the C API.
+        Ok(unsafe { (*self.ptr.add(index)).driver_data })
+    }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index d1c0f136952e..2dd134a46285 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -41,6 +41,8 @@
 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 V7 12/16] rust: Extend cpufreq bindings for policy and driver ops

[Viresh Kumar]

This extends the cpufreq bindings with bindings for cpufreq policy and
driver operations.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/cpufreq.rs | 357 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 355 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 3dfdf5ccb9b8..8468e12ef1f5 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -7,15 +7,20 @@
 //! C header: [`include/linux/cpufreq.h`](srctree/include/linux/cpufreq.h)
 
 use crate::{
-    bindings,
-    error::{code::*, to_result, Result},
+    bindings, clk, cpumask,
+    device::Device,
+    error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
     prelude::*,
+    types::ForeignOwnable,
 };
 
 use core::{
     pin::Pin,
+    ptr::self,
 };
 
+use macros::vtable;
+
 /// Default transition latency value.
 pub const ETERNAL_LATENCY: u32 = bindings::CPUFREQ_ETERNAL as u32;
 
@@ -229,3 +234,351 @@ pub fn data(&self, index: usize) -> Result<u32> {
         Ok(unsafe { (*self.ptr.add(index)).driver_data })
     }
 }
+
+/// Equivalent to `struct cpufreq_policy` in the C code.
+pub struct Policy {
+    ptr: *mut bindings::cpufreq_policy,
+    put_cpu: bool,
+    cpumask: cpumask::Cpumask,
+}
+
+impl Policy {
+    /// Creates a new instance of [`Policy`].
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that `ptr` is valid and non-null.
+    pub unsafe fn from_raw_policy(ptr: *mut bindings::cpufreq_policy) -> Self {
+        Self {
+            ptr,
+            put_cpu: false,
+            // SAFETY: The pointer is guaranteed to be valid for the lifetime of `Self`. The `cpus`
+            // pointer is guaranteed to be valid by the C code.
+            cpumask: unsafe { cpumask::Cpumask::get_cpumask((*ptr).cpus) },
+        }
+    }
+
+    fn from_cpu(cpu: u32) -> Result<Self> {
+        // SAFETY: It is safe to call `cpufreq_cpu_get()` for any CPU.
+        let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?;
+
+        // SAFETY: The pointer is guaranteed to be valid by the C code.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+        policy.put_cpu = true;
+        Ok(policy)
+    }
+
+    /// Raw pointer to the underlying cpufreq policy.
+    #[inline]
+    pub fn as_raw(&self) -> *mut bindings::cpufreq_policy {
+        self.ptr
+    }
+
+    fn as_ref(&self) -> &bindings::cpufreq_policy {
+        // SAFETY: By the type invariants, we know that `self` owns a reference to the pointer.
+        unsafe { &(*self.ptr) }
+    }
+    fn as_mut_ref(&mut self) -> &mut bindings::cpufreq_policy {
+        // SAFETY: By the type invariants, we know that `self` owns a reference to the pointer.
+        unsafe { &mut (*self.ptr) }
+    }
+
+    /// Returns the primary CPU for a cpufreq policy.
+    pub fn cpu(&self) -> u32 {
+        self.as_ref().cpu
+    }
+
+    /// Returns the minimum frequency for a cpufreq policy.
+    pub fn min(&self) -> u32 {
+        self.as_ref().min
+    }
+
+    /// Set the minimum frequency for a cpufreq policy.
+    pub fn set_min(&mut self, min: u32) -> &mut Self {
+        self.as_mut_ref().min = min;
+        self
+    }
+
+    /// Returns the maximum frequency for a cpufreq policy.
+    pub fn max(&self) -> u32 {
+        self.as_ref().max
+    }
+
+    /// Set the maximum frequency for a cpufreq policy.
+    pub fn set_max(&mut self, max: u32) -> &mut Self {
+        self.as_mut_ref().max = max;
+        self
+    }
+
+    /// Returns the current frequency for a cpufreq policy.
+    pub fn cur(&self) -> u32 {
+        self.as_ref().cur
+    }
+
+    /// Sets the suspend frequency for a cpufreq policy.
+    pub fn set_suspend_freq(&mut self, freq: u32) -> &mut Self {
+        self.as_mut_ref().suspend_freq = freq;
+        self
+    }
+
+    /// Returns the suspend frequency for a cpufreq policy.
+    pub fn suspend_freq(&self) -> u32 {
+        self.as_ref().suspend_freq
+    }
+
+    /// Provides a wrapper to the generic suspend routine.
+    pub fn generic_suspend(&self) -> Result<()> {
+        // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+        // use it now.
+        to_result(unsafe { bindings::cpufreq_generic_suspend(self.as_raw()) })
+    }
+
+    /// Provides a wrapper to the generic get routine.
+    pub fn generic_get(&self) -> Result<u32> {
+        // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+        // use it now.
+        Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) })
+    }
+
+    /// Provides a wrapper to the register em with OPP routine.
+    pub fn register_em_opp(&self) {
+        // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+        // use it now.
+        unsafe { bindings::cpufreq_register_em_with_opp(self.as_raw()) };
+    }
+
+    /// Gets raw pointer to cpufreq policy's CPUs mask.
+    pub fn cpus(&mut self) -> &mut cpumask::Cpumask {
+        &mut self.cpumask
+    }
+
+    /// Sets clock for a cpufreq policy.
+    pub fn set_clk(&mut self, dev: &Device, name: Option<&CStr>) -> Result<clk::Clk> {
+        let clk = clk::Clk::new(dev, name)?;
+        self.as_mut_ref().clk = clk.as_raw();
+        Ok(clk)
+    }
+
+    /// Allows frequency switching code to run on any CPU.
+    pub fn set_dvfs_possible_from_any_cpu(&mut self) -> &mut Self {
+        self.as_mut_ref().dvfs_possible_from_any_cpu = true;
+        self
+    }
+
+    /// Get fast_switch_possible value.
+    pub fn fast_switch_possible(&self) -> bool {
+        self.as_ref().fast_switch_possible
+    }
+
+    /// Enable/disable fast frequency switching.
+    pub fn set_fast_switch_possible(&mut self, val: bool) -> &mut Self {
+        self.as_mut_ref().fast_switch_possible = val;
+        self
+    }
+
+    /// Sets transition latency for a cpufreq policy.
+    pub fn set_transition_latency(&mut self, latency: u32) -> &mut Self {
+        self.as_mut_ref().cpuinfo.transition_latency = latency;
+        self
+    }
+
+    /// Set cpuinfo.min_freq.
+    pub fn set_cpuinfo_min_freq(&mut self, min_freq: u32) -> &mut Self {
+        self.as_mut_ref().cpuinfo.min_freq = min_freq;
+        self
+    }
+
+    /// Set cpuinfo.max_freq.
+    pub fn set_cpuinfo_max_freq(&mut self, max_freq: u32) -> &mut Self {
+        self.as_mut_ref().cpuinfo.max_freq = max_freq;
+        self
+    }
+
+    /// Set transition_delay_us, i.e. time between successive freq. change requests.
+    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 the cpufreq table for a cpufreq policy. The cpufreq table is recreated in a
+    /// light-weight manner from the raw pointer. The table in C code is not freed once this table
+    /// is dropped.
+    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.
+        Ok(unsafe { Table::from_raw(self.as_ref().freq_table) })
+    }
+
+    /// Sets the cpufreq table for a cpufreq policy.
+    ///
+    /// The cpufreq driver must guarantee that the frequency table does not get freed while it is
+    /// still being used by the C code.
+    pub fn set_freq_table(&mut self, table: &Table) -> &mut Self {
+        self.as_mut_ref().freq_table = table.as_raw();
+        self
+    }
+
+    /// Returns the data for a cpufreq policy.
+    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 by us from [`set_data()`].
+            Some(unsafe { T::borrow(self.as_ref().driver_data) })
+        }
+    }
+
+    // Sets the data for a cpufreq policy.
+    fn set_data<T: ForeignOwnable>(&mut self, data: T) -> Result<()> {
+        if self.as_ref().driver_data.is_null() {
+            // Pass 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)
+        }
+    }
+
+    // Returns the data for a cpufreq policy.
+    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
+        }
+    }
+}
+
+impl Drop for Policy {
+    fn drop(&mut self) {
+        if self.put_cpu {
+            // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+            // relinquish it now.
+            unsafe { bindings::cpufreq_cpu_put(self.as_raw()) };
+        }
+    }
+}
+
+/// Operations to be implemented by a cpufreq driver.
+#[vtable]
+pub trait Driver {
+    /// Driver specific data.
+    ///
+    /// Corresponds to the data retrieved via the kernel's
+    /// `cpufreq_get_driver_data()` function.
+    ///
+    /// Require that `Data` implements `ForeignOwnable`. We guarantee to
+    /// never move the underlying wrapped data structure.
+    type Data: ForeignOwnable;
+
+    /// Policy specific data.
+    ///
+    /// Require that `PData` implements `ForeignOwnable`. We guarantee to
+    /// never move the underlying wrapped data structure.
+    type PData: ForeignOwnable;
+
+    /// Policy's init callback.
+    fn init(policy: &mut Policy) -> Result<Self::PData>;
+
+    /// Policy's exit callback.
+    fn exit(_policy: &mut Policy, _data: Option<Self::PData>) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's online callback.
+    fn online(_policy: &mut Policy) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's offline callback.
+    fn offline(_policy: &mut Policy) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's suspend callback.
+    fn suspend(_policy: &mut Policy) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's resume callback.
+    fn resume(_policy: &mut Policy) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's ready callback.
+    fn ready(_policy: &mut Policy) {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's verify callback.
+    fn verify(data: &mut PolicyData) -> Result<()>;
+
+    /// Policy's setpolicy callback.
+    fn setpolicy(_policy: &mut Policy) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's target callback.
+    fn target(_policy: &mut Policy, _target_freq: u32, _relation: Relation) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's target_index callback.
+    fn target_index(_policy: &mut Policy, _index: u32) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's fast_switch callback.
+    fn fast_switch(_policy: &mut Policy, _target_freq: u32) -> u32 {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's adjust_perf callback.
+    fn adjust_perf(_policy: &mut Policy, _min_perf: usize, _target_perf: usize, _capacity: usize) {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's get_intermediate callback.
+    fn get_intermediate(_policy: &mut Policy, _index: u32) -> u32 {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's target_intermediate callback.
+    fn target_intermediate(_policy: &mut Policy, _index: u32) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's get callback.
+    fn get(_policy: &mut Policy) -> Result<u32> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's update_limits callback.
+    fn update_limits(_policy: &mut Policy) {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's bios_limit callback.
+    fn bios_limit(_policy: &mut Policy, _limit: &mut u32) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's set_boost callback.
+    fn set_boost(_policy: &mut Policy, _state: i32) -> Result<()> {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
+    /// Policy's register_em callback.
+    fn register_em(_policy: &mut Policy) {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+}
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 13/16] rust: Extend cpufreq bindings for driver registration

[Viresh Kumar]

This extends the cpufreq bindings with bindings for registering a
driver.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/cpufreq.rs | 476 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 474 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 8468e12ef1f5..899f5b50eb7c 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -9,14 +9,17 @@
 use crate::{
     bindings, clk, cpumask,
     device::Device,
-    error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR},
+    devres::Devres,
+    error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
     prelude::*,
     types::ForeignOwnable,
 };
 
 use core::{
+    cell::UnsafeCell,
+    marker::PhantomData,
     pin::Pin,
-    ptr::self,
+    ptr::{self, addr_of_mut},
 };
 
 use macros::vtable;
@@ -582,3 +585,472 @@ fn register_em(_policy: &mut Policy) {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 }
+
+/// Registration of a cpufreq driver.
+pub struct Registration<T: Driver> {
+    drv: KBox<UnsafeCell<bindings::cpufreq_driver>>,
+    _p: PhantomData<T>,
+}
+
+// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads
+// or CPUs, so it is safe to share it.
+unsafe impl<T: Driver> Sync for Registration<T> {}
+
+#[allow(clippy::non_send_fields_in_send_ty)]
+// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any thread.
+// Additionally, `T::Data` (which is dropped during unregistration) is `Send`, so it is okay to move
+// `Registration` to different threads.
+unsafe impl<T: Driver> Send for Registration<T> {}
+
+impl<T: Driver> Registration<T> {
+    /// Registers a cpufreq driver with the rest of the kernel.
+    pub fn new(name: &'static CStr, data: T::Data, flags: u16, boost: bool) -> Result<Self> {
+        let mut drv = KBox::new(
+            UnsafeCell::new(bindings::cpufreq_driver::default()),
+            GFP_KERNEL,
+        )?;
+        let drv_ref = drv.get_mut();
+
+        // Account for the trailing null character.
+        let len = name.len() + 1;
+        if len > drv_ref.name.len() {
+            return Err(EINVAL);
+        };
+
+        // SAFETY: `name` is a valid Cstr, and we are copying it to an array of equal or larger
+        // size.
+        let name = unsafe { &*(name.as_bytes_with_nul() as *const [u8]) };
+        drv_ref.name[..len].copy_from_slice(name);
+
+        drv_ref.boost_enabled = boost;
+        drv_ref.flags = flags;
+
+        // Allocate an array of 3 pointers to be passed to the C code.
+        let mut attr = KBox::new([ptr::null_mut(); 3], GFP_KERNEL)?;
+        let mut next = 0;
+
+        // SAFETY: The C code returns a valid pointer here, which is again passed to the C code in
+        // an array.
+        attr[next] = unsafe {
+            addr_of_mut!(bindings::cpufreq_freq_attr_scaling_available_freqs) as *mut _
+        };
+        next += 1;
+
+        if boost {
+            // SAFETY: The C code returns a valid pointer here, which is again passed to the C code
+            // in an array.
+            attr[next] = unsafe {
+                addr_of_mut!(bindings::cpufreq_freq_attr_scaling_boost_freqs) as *mut _
+            };
+            next += 1;
+        }
+        attr[next] = ptr::null_mut();
+
+        // Pass the ownership of the memory block to the C code. This will be freed when
+        // the [`Registration`] object goes out of scope.
+        drv_ref.attr = KBox::leak(attr) as *mut _;
+
+        // Initialize mandatory callbacks.
+        drv_ref.init = Some(Self::init_callback);
+        drv_ref.verify = Some(Self::verify_callback);
+
+        // Initialize optional callbacks.
+        drv_ref.setpolicy = if T::HAS_SETPOLICY {
+            Some(Self::setpolicy_callback)
+        } else {
+            None
+        };
+        drv_ref.target = if T::HAS_TARGET {
+            Some(Self::target_callback)
+        } else {
+            None
+        };
+        drv_ref.target_index = if T::HAS_TARGET_INDEX {
+            Some(Self::target_index_callback)
+        } else {
+            None
+        };
+        drv_ref.fast_switch = if T::HAS_FAST_SWITCH {
+            Some(Self::fast_switch_callback)
+        } else {
+            None
+        };
+        drv_ref.adjust_perf = if T::HAS_ADJUST_PERF {
+            Some(Self::adjust_perf_callback)
+        } else {
+            None
+        };
+        drv_ref.get_intermediate = if T::HAS_GET_INTERMEDIATE {
+            Some(Self::get_intermediate_callback)
+        } else {
+            None
+        };
+        drv_ref.target_intermediate = if T::HAS_TARGET_INTERMEDIATE {
+            Some(Self::target_intermediate_callback)
+        } else {
+            None
+        };
+        drv_ref.get = if T::HAS_GET {
+            Some(Self::get_callback)
+        } else {
+            None
+        };
+        drv_ref.update_limits = if T::HAS_UPDATE_LIMITS {
+            Some(Self::update_limits_callback)
+        } else {
+            None
+        };
+        drv_ref.bios_limit = if T::HAS_BIOS_LIMIT {
+            Some(Self::bios_limit_callback)
+        } else {
+            None
+        };
+        drv_ref.online = if T::HAS_ONLINE {
+            Some(Self::online_callback)
+        } else {
+            None
+        };
+        drv_ref.offline = if T::HAS_OFFLINE {
+            Some(Self::offline_callback)
+        } else {
+            None
+        };
+        drv_ref.exit = if T::HAS_EXIT {
+            Some(Self::exit_callback)
+        } else {
+            None
+        };
+        drv_ref.suspend = if T::HAS_SUSPEND {
+            Some(Self::suspend_callback)
+        } else {
+            None
+        };
+        drv_ref.resume = if T::HAS_RESUME {
+            Some(Self::resume_callback)
+        } else {
+            None
+        };
+        drv_ref.ready = if T::HAS_READY {
+            Some(Self::ready_callback)
+        } else {
+            None
+        };
+        drv_ref.set_boost = if T::HAS_SET_BOOST {
+            Some(Self::set_boost_callback)
+        } else {
+            None
+        };
+        drv_ref.register_em = if T::HAS_REGISTER_EM {
+            Some(Self::register_em_callback)
+        } else {
+            None
+        };
+
+        // Set driver data before registering the driver, as the cpufreq core may call few
+        // callbacks before `cpufreq_register_driver()` returns.
+        Self::set_data(drv_ref, data)?;
+
+        // SAFETY: It is safe to register the driver with the cpufreq core in the C code.
+        to_result(unsafe { bindings::cpufreq_register_driver(drv_ref) })?;
+
+        Ok(Self {
+            drv,
+            _p: PhantomData,
+        })
+    }
+
+    /// Same as [Registration::new`], but does not return a `Registration` instance.
+    /// Instead the `Registration` is owned by devres and will be revoked / dropped, once the
+    /// device is detached.
+    pub fn new_foreign_owned(
+        dev: &Device,
+        name: &'static CStr,
+        data: T::Data,
+        flags: u16,
+        boost: bool,
+    ) -> Result<()> {
+        let reg = Self::new(name, data, flags, boost)?;
+        Devres::new_foreign_owned(dev, reg, GFP_KERNEL)?;
+        Ok(())
+    }
+
+    // Sets the data for a cpufreq driver.
+    fn set_data(drv: &mut bindings::cpufreq_driver, data: T::Data) -> Result<()> {
+        if drv.driver_data.is_null() {
+            // Pass the ownership of the data to the foreign interface.
+            drv.driver_data = <T::Data as ForeignOwnable>::into_foreign(data) as _;
+            Ok(())
+        } else {
+            Err(EBUSY)
+        }
+    }
+
+    /// Returns the previous set data for a cpufreq driver.
+    pub fn data(&mut self) -> Option<<T::Data as ForeignOwnable>::Borrowed<'static>> {
+        let drv = self.drv.get_mut();
+
+        if drv.driver_data.is_null() {
+            None
+        } else {
+            // SAFETY: The data is earlier set by us from [`set_data()`].
+            Some(unsafe { <T::Data as ForeignOwnable>::borrow(drv.driver_data) })
+        }
+    }
+
+    // Clears and returns the data for a cpufreq driver.
+    fn clear_data(&mut self) -> Option<T::Data> {
+        let drv = self.drv.get_mut();
+
+        if drv.driver_data.is_null() {
+            None
+        } else {
+            // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to
+            // relinquish it now.
+            let data = Some(unsafe { <T::Data as ForeignOwnable>::from_foreign(drv.driver_data) });
+            drv.driver_data = ptr::null_mut();
+            data
+        }
+    }
+}
+
+// cpufreq driver callbacks.
+impl<T: Driver> Registration<T> {
+    // Policy's init callback.
+    extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+
+            let data = T::init(&mut policy)?;
+            policy.set_data(data)?;
+            Ok(0)
+        })
+    }
+
+    // Policy's exit callback.
+    extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) {
+        // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of
+        // `ptr`.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+
+        let data = policy.clear_data();
+        let _ = T::exit(&mut policy, data);
+    }
+
+    // Policy's online callback.
+    extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::online(&mut policy).map(|()| 0)
+        })
+    }
+
+    // Policy's offline callback.
+    extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::offline(&mut policy).map(|()| 0)
+        })
+    }
+
+    // Policy's suspend callback.
+    extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::suspend(&mut policy).map(|()| 0)
+        })
+    }
+
+    // Policy's resume callback.
+    extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::resume(&mut policy).map(|()| 0)
+        })
+    }
+
+    // Policy's ready callback.
+    extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) {
+        // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of
+        // `ptr`.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+        T::ready(&mut policy);
+    }
+
+    // Policy's verify callback.
+    extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut data = unsafe { PolicyData::from_raw_policy_data(ptr) };
+            T::verify(&mut data).map(|()| 0)
+        })
+    }
+
+    // Policy's setpolicy callback.
+    extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::setpolicy(&mut policy).map(|()| 0)
+        })
+    }
+
+    // Policy's target callback.
+    extern "C" fn target_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        target_freq: u32,
+        relation: u32,
+    ) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::target(&mut policy, target_freq, Relation::new(relation)?).map(|()| 0)
+        })
+    }
+
+    // Policy's target_index callback.
+    extern "C" fn target_index_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        index: u32,
+    ) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::target_index(&mut policy, index).map(|()| 0)
+        })
+    }
+
+    // Policy's fast_switch callback.
+    extern "C" fn fast_switch_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        target_freq: u32,
+    ) -> core::ffi::c_uint {
+        // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of
+        // `ptr`.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+        T::fast_switch(&mut policy, target_freq)
+    }
+
+    // Policy'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) = Policy::from_cpu(cpu) {
+            T::adjust_perf(&mut policy, min_perf, target_perf, capacity);
+        }
+    }
+
+    // Policy's get_intermediate callback.
+    extern "C" fn get_intermediate_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        index: u32,
+    ) -> core::ffi::c_uint {
+        // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of
+        // `ptr`.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+        T::get_intermediate(&mut policy, index)
+    }
+
+    // Policy's target_intermediate callback.
+    extern "C" fn target_intermediate_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        index: u32,
+    ) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::target_intermediate(&mut policy, index).map(|()| 0)
+        })
+    }
+
+    // Policy's get callback.
+    extern "C" fn get_callback(cpu: u32) -> core::ffi::c_uint {
+        Policy::from_cpu(cpu).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f))
+    }
+
+    // Policy's update_limit callback.
+    extern "C" fn update_limits_callback(cpu: u32) {
+        if let Ok(mut policy) = Policy::from_cpu(cpu) {
+            T::update_limits(&mut policy);
+        }
+    }
+
+    // Policy's bios_limit callback.
+    extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> core::ffi::c_int {
+        from_result(|| {
+            let mut policy = Policy::from_cpu(cpu as u32)?;
+
+            // SAFETY: The pointer is guaranteed by the C code to be valid.
+            T::bios_limit(&mut policy, &mut (unsafe { *limit })).map(|()| 0)
+        })
+    }
+
+    // Policy's set_boost callback.
+    extern "C" fn set_boost_callback(
+        ptr: *mut bindings::cpufreq_policy,
+        state: i32,
+    ) -> core::ffi::c_int {
+        from_result(|| {
+            // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+            // duration of this call, so it is guaranteed to remain alive for the lifetime of
+            // `ptr`.
+            let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+            T::set_boost(&mut policy, state).map(|()| 0)
+        })
+    }
+
+    // Policy's register_em callback.
+    extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) {
+        // SAFETY: `ptr` is valid by the contract with the C code. `policy` is alive only for the
+        // duration of this call, so it is guaranteed to remain alive for the lifetime of
+        // `ptr`.
+        let mut policy = unsafe { Policy::from_raw_policy(ptr) };
+        T::register_em(&mut policy);
+    }
+}
+
+impl<T: Driver> Drop for Registration<T> {
+    // Removes the registration from the kernel if it has completed successfully before.
+    fn drop(&mut self) {
+        pr_info!("Registration dropped\n");
+        let drv = self.drv.get_mut();
+
+        // SAFETY: The driver was earlier registered from `new()`.
+        unsafe { bindings::cpufreq_unregister_driver(drv) };
+
+        // Free the previously leaked memory to the C code.
+        if !drv.attr.is_null() {
+            // SAFETY: The pointer was earlier initialized from the result of `KBox::leak`.
+            unsafe { drop(KBox::from_raw(drv.attr)) };
+        }
+
+        // Free data
+        drop(self.clear_data());
+    }
+}
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 14/16] rust: Extend OPP bindings with CPU frequency table

[Viresh Kumar]

This commit adds bindings for CPUFreq core related API.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 rust/kernel/opp.rs | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
index 22c4d543f456..147178410c60 100644
--- a/rust/kernel/opp.rs
+++ b/rust/kernel/opp.rs
@@ -16,6 +16,12 @@
     types::{ARef, AlwaysRefCounted, Opaque},
 };
 
+#[cfg(CONFIG_CPU_FREQ)]
+use crate::cpufreq;
+
+#[cfg(CONFIG_CPU_FREQ)]
+use core::ops::Deref;
+
 use core::{marker::PhantomData, ptr};
 
 use macros::vtable;
@@ -337,6 +343,56 @@ extern "C" fn config_regulators(
     }
 }
 
+/// CPU Frequency table created from OPP entries.
+#[cfg(CONFIG_CPU_FREQ)]
+pub struct FreqTable {
+    dev: ARef<Device>,
+    table: cpufreq::Table,
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl FreqTable {
+    /// Creates new instance of [`FreqTable`] from raw pointer.
+    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(),
+            // SAFETY: The `ptr` is guaranteed by the C code to be valid.
+            table: unsafe { cpufreq::Table::from_raw(ptr) },
+        })
+    }
+
+    /// Returns reference to the underlying [`cpufreq::Table`].
+    pub fn table(&self) -> &cpufreq::Table {
+        &self.table
+    }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl Deref for FreqTable {
+    type Target = cpufreq::Table;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        &self.table
+    }
+}
+
+#[cfg(CONFIG_CPU_FREQ)]
+impl Drop for FreqTable {
+    fn drop(&mut self) {
+        // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
+        // requirements.
+        unsafe { bindings::dev_pm_opp_free_cpufreq_table(self.dev.as_raw(), &mut self.as_raw()) };
+    }
+}
+
 /// Operating performance point (OPP) table.
 ///
 /// Wraps the kernel's `struct opp_table`.
@@ -541,6 +597,12 @@ pub fn adjust_voltage(
         })
     }
 
+    /// Create cpufreq table from OPP table.
+    #[cfg(CONFIG_CPU_FREQ)]
+    pub fn to_cpufreq_table(&mut self) -> Result<FreqTable> {
+        FreqTable::new(self)
+    }
+
     /// Sets a matching OPP based on frequency.
     pub fn set_rate(&self, freq: usize) -> Result<()> {
         // SAFETY: The requirements are satisfied by the existence of `Device` and its safety
-- 
2.31.1.272.g89b43f80a514

[PATCH V7 15/16] cpufreq: Add Rust based cpufreq-dt driver

[Viresh Kumar]

This commit adds a Rust based cpufreq-dt driver, which covers most of
the functionality of the existing C based driver. Only a handful of
things are left, like fetching platform data from cpufreq-dt-platdev.c.

This is tested with the help of QEMU for now and switching of
frequencies work as expected.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/Kconfig        |  12 ++
 drivers/cpufreq/Makefile       |   1 +
 drivers/cpufreq/rcpufreq_dt.rs | 230 +++++++++++++++++++++++++++++++++
 3 files changed, 243 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 d35a28dd9463..db38d1d5562d 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..9f761082fa14
--- /dev/null
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust based implementation of the cpufreq-dt driver.
+
+use core::format_args;
+
+use kernel::{
+    c_str, clk, cpu, cpufreq, cpumask::Cpumask, device::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 name_cstr = CString::try_from_fmt(fmt!("{}-supply", name)).ok()?;
+
+    if dev.property_present(&name_cstr) {
+        CString::try_from_fmt(fmt!("{}", name)).ok()
+    } else {
+        None
+    }
+}
+
+// Finds supply name for the CPU from DT.
+fn find_supply_names(dev: &Device, cpu: u32) -> Option<KVec<CString>> {
+    // Try "cpu0" for older DTs.
+    let name = match cpu {
+        0 => find_supply_name_exact(dev, "cpu0"),
+        _ => None,
+    }
+    .or(find_supply_name_exact(dev, "cpu"))?;
+
+    let mut list = KVec::with_capacity(1, GFP_KERNEL).ok()?;
+    list.push(name, GFP_KERNEL).ok()?;
+
+    Some(list)
+}
+
+// Represents the cpufreq dt device.
+struct CPUFreqDTDevice {
+    opp_table: opp::Table,
+    freq_table: opp::FreqTable,
+    #[allow(dead_code)]
+    mask: Cpumask,
+    #[allow(dead_code)]
+    token: Option<opp::ConfigToken>,
+    #[allow(dead_code)]
+    clk: clk::Clk,
+}
+
+struct CPUFreqDTDriver {
+    _pdev: platform::Device,
+}
+
+#[vtable]
+impl opp::ConfigOps for CPUFreqDTDriver {}
+
+#[vtable]
+impl cpufreq::Driver for CPUFreqDTDriver {
+    type Data = ();
+    type PData = Arc<CPUFreqDTDevice>;
+
+    fn init(policy: &mut cpufreq::Policy) -> Result<Self::PData> {
+        let cpu = policy.cpu();
+        let dev = cpu::from_cpu(cpu)?;
+        let mut mask = Cpumask::new()?;
+
+        mask.set(cpu);
+
+        let token = match find_supply_names(dev, cpu) {
+            Some(names) => Some(
+                opp::Config::<Self>::new()
+                    .set_regulator_names(names)?
+                    .set(dev)?,
+            ),
+            _ => None,
+        };
+
+        // 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 {
+                    return Err(e);
+                }
+
+                // "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()
+            }
+        };
+
+        // 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.set_all();
+            opp_table.set_sharing_cpus(&mut mask)?;
+        }
+
+        let mut transition_latency = opp_table.max_transition_latency() as u32;
+        if transition_latency == 0 {
+            transition_latency = cpufreq::ETERNAL_LATENCY;
+        }
+
+        let freq_table = opp_table.to_cpufreq_table()?;
+        let clk = policy
+            .set_freq_table(freq_table.table())
+            .set_dvfs_possible_from_any_cpu()
+            .set_suspend_freq((opp_table.suspend_freq() / 1000) as u32)
+            .set_transition_latency(transition_latency)
+            .set_clk(dev, None)?;
+
+        mask.copy(policy.cpus());
+
+        Ok(Arc::new(
+            CPUFreqDTDevice {
+                opp_table,
+                freq_table,
+                mask,
+                token,
+                clk,
+            },
+            GFP_KERNEL,
+        )?)
+    }
+
+    fn exit(_policy: &mut cpufreq::Policy, _data: Option<Self::PData>) -> Result<()> {
+        Ok(())
+    }
+
+    fn online(_policy: &mut cpufreq::Policy) -> Result<()> {
+        // We did light-weight tear down earlier, nothing to do here.
+        Ok(())
+    }
+
+    fn offline(_policy: &mut cpufreq::Policy) -> Result<()> {
+        // Preserve policy->data and don't free resources on light-weight
+        // tear down.
+        Ok(())
+    }
+
+    fn suspend(policy: &mut cpufreq::Policy) -> Result<()> {
+        policy.generic_suspend()
+    }
+
+    fn verify(data: &mut cpufreq::PolicyData) -> Result<()> {
+        data.generic_verify()
+    }
+
+    fn target_index(policy: &mut cpufreq::Policy, index: u32) -> Result<()> {
+        let data = match policy.data::<Self::PData>() {
+            Some(data) => data,
+            None => return Err(ENOENT),
+        };
+
+        let freq = data.freq_table.freq(index.try_into().unwrap())? as usize;
+        data.opp_table.set_rate(freq * 1000)
+    }
+
+    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: &mut platform::Device, _id_info: Option<&Self::IdInfo>) -> Result<Pin<KBox<Self>>> {
+        cpufreq::Registration::<CPUFreqDTDriver>::new_foreign_owned(
+            pdev.as_ref(),
+            c_str!("cpufreq-dt"),
+            (),
+            cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV,
+            true,
+        )?;
+
+        let drvdata = KBox::new(Self { _pdev: pdev.clone() }, 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

[PATCH V7 16/16] DO-NOT_MERGE: cpufreq: Rename cpufreq-dt platdev

[Viresh Kumar]

The module! implementation in the Rust code expects a module name
without a '-' symbol, else it fails to compile with following errors:

error: expected one of `:`, `;`, or `=`, found `-`
   --> drivers/cpufreq/rcpufreq_dt.rs:247:1
    |
247 | / module_platform_driver! {
248 | |     type: CPUFreqDTDriver,
249 | |     name: "cpufreq-dt",
250 | |     author: "Viresh Kumar <viresh.kumar@linaro.org>",
251 | |     description: "Generic CPUFreq DT driver",
252 | |     license: "GPL v2",
253 | | }
    | |_^ expected one of `:`, `;`, or `=`
    |
    = note: this error originates in the macro `$crate::prelude::module` which comes from the expansion of the macro `module_platform_driver` (in Nightly builds, run with -Z macro-backtrace for more info)

This must be fixed properly in the Rust code instead. Not to be merged.

Not-Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq-dt-platdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index 9c198bd4f7e9..263e1e97538d 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -230,7 +230,7 @@ static int __init cpufreq_dt_platdev_init(void)
 	return -ENODEV;
 
 create_pdev:
-	return PTR_ERR_OR_ZERO(platform_device_register_data(NULL, "cpufreq-dt",
+	return PTR_ERR_OR_ZERO(platform_device_register_data(NULL, "cpufreq_dt",
 			       -1, data,
 			       sizeof(struct cpufreq_dt_platform_data)));
 }
-- 
2.31.1.272.g89b43f80a514

[PATCH] rust: macros: enable use of hyphens in module names

[Anisse Astier]

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>
---
Hello Viresh,

Does this solve you problem ?

Regards,

Anisse
---
 rust/macros/module.rs | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index aef3b132f32b..4cac332087b0 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -182,7 +182,9 @@ 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);
     }
@@ -292,14 +294,14 @@ mod __module_init {{
                     #[doc(hidden)]
                     #[link_section = \"{initcall_section}\"]
                     #[used]
-                    pub static __{name}_initcall: extern \"C\" fn() -> core::ffi::c_int = __{name}_init;
+                    pub static __{name_identifier}_initcall: extern \"C\" fn() -> core::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
                         \"#
                     );
@@ -307,7 +309,7 @@ mod __module_init {{
                     #[cfg(not(MODULE))]
                     #[doc(hidden)]
                     #[no_mangle]
-                    pub extern \"C\" fn __{name}_init() -> core::ffi::c_int {{
+                    pub extern \"C\" fn __{name_identifier}_init() -> core::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.
@@ -317,12 +319,12 @@ 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`
+                        // - furthermore it is only called after `__{name_identifier}_init` has returned `0`
                         //   (which delegates to `__init`).
                         unsafe {{ __exit() }}
                     }}
@@ -369,6 +371,7 @@ unsafe fn __exit() {{
         ",
         type_ = info.type_,
         name = info.name,
+        name_identifier = name_identifier,
         modinfo = modinfo.buffer,
         initcall_section = ".initcall6.init"
     )
-- 
2.48.1

[PATCH v2] rust: macros: enable use of hyphens in module names

[Anisse Astier]

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>
---
Hello,

Change since v1:
 - rebase on branch rfl/staging/dev

Sorry for sending a v2 so quickly, but v1 was based on the wrong branch :-/

Kind regards,

Anisse
---
 rust/macros/module.rs | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index cdf94f4982df..1eff30d2ca6a 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -182,7 +182,9 @@ 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);
     }
@@ -298,14 +300,14 @@ 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
                         \"#
                     );
@@ -313,7 +315,7 @@ 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.
@@ -323,12 +325,12 @@ 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`
+                        // - furthermore it is only called after `__{name_identifier}_init` has returned `0`
                         //   (which delegates to `__init`).
                         unsafe {{ __exit() }}
                     }}
@@ -369,6 +371,7 @@ unsafe fn __exit() {{
         ",
         type_ = info.type_,
         name = info.name,
+        name_identifier = name_identifier,
         modinfo = modinfo.buffer,
         initcall_section = ".initcall6.init"
     )
-- 
2.48.1

Re: [PATCH v2] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

On 22-01-25, 14:39, Anisse Astier wrote:
> 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>
> ---
> Hello,
> 
> Change since v1:
>  - rebase on branch rfl/staging/dev

Tested-by: Viresh Kumar <viresh.kumar@linaro.org>

Thanks for the fix.

-- 
viresh

Re: [PATCH v2] rust: macros: enable use of hyphens in module names

[Viresh Kumar]

On 22-01-25, 14:39, Anisse Astier wrote:
> +    /* Rust does not allow hyphens in identifiers, use underscore instead */
> +    let name_identifier = info.name.replace("-", "_");

With CLIPPY=1 W=1, this gives:

warning: single-character string constant used as pattern
   --> /mnt/ssd/all/work/repos/kernel/linux/rust/macros/module.rs:186:45
    |
186 |     let name_identifier = info.name.replace("-", "_");
    |                                             ^^^ help: consider using a `char`: `'-'`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#single_char_pattern
    = note: `-W clippy::single-char-pattern` implied by `-W clippy::all`
    = help: to override `-W clippy::all` add `#[allow(clippy::single_char_pattern)]`

warning: 1 warning emitted

This fixes it:

diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 1eff30d2ca6a..2e740bbdb598 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -183,7 +183,7 @@ 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 name_identifier = info.name.replace('-', "_");
     let mut modinfo = ModInfoBuilder::new(name_identifier.as_ref());
     if let Some(author) = info.author {
         modinfo.emit("author", &author);


Will include it in my V8 now, unless you have any objections to it.
Thanks.

-- 
viresh

Re: [PATCH v2] rust: macros: enable use of hyphens in module names

[Anisse Astier]

Jeu 30 janv 2025, à 05:58, Viresh Kumar a écrit :
> On 22-01-25, 14:39, Anisse Astier wrote:
>> +    /* Rust does not allow hyphens in identifiers, use underscore instead */
>> +    let name_identifier = info.name.replace("-", "_");
>
> With CLIPPY=1 W=1, this gives:
>
> warning: single-character string constant used as pattern
>    --> /mnt/ssd/all/work/repos/kernel/linux/rust/macros/module.rs:186:45
>     |
> 186 |     let name_identifier = info.name.replace("-", "_");
>     |                                             ^^^ help: consider 
> using a `char`: `'-'`
>     |
>     = help: for further information visit 
> https://rust-lang.github.io/rust-clippy/master/index.html#single_char_pattern
>     = note: `-W clippy::single-char-pattern` implied by `-W clippy::all`
>     = help: to override `-W clippy::all` add 
> `#[allow(clippy::single_char_pattern)]`
>
> warning: 1 warning emitted
>
> This fixes it:
>
> diff --git a/rust/macros/module.rs b/rust/macros/module.rs
> index 1eff30d2ca6a..2e740bbdb598 100644
> --- a/rust/macros/module.rs
> +++ b/rust/macros/module.rs
> @@ -183,7 +183,7 @@ 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 name_identifier = info.name.replace('-', "_");
>      let mut modinfo = ModInfoBuilder::new(name_identifier.as_ref());
>      if let Some(author) = info.author {
>          modinfo.emit("author", &author);
>
>
> Will include it in my V8 now, unless you have any objections to it.

No objections and nice catch!

Regards,

Anisse 

Re: [PATCH v2] rust: macros: enable use of hyphens in module names

[Alice Ryhl]

On Wed, Jan 22, 2025 at 2:39 PM Anisse Astier <anisse@astier.eu> wrote:
>
> 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>