[PATCH V5 0/8] Rust bindings for cpufreq and OPP core + sample driver

[Viresh Kumar <viresh.kumar@linaro.org>]

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 series depends on foundational bindings for several other modules,
including device/driver, platform driver, OF (Device Tree), clock, and cpumask.
Support for these modules is not yet intended for upstream inclusion.

The work is based on `staging/rust-device` from the Rust tree, which is derived
from v6.10-rc1.

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 (8):
  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

 MAINTAINERS                     |    2 +
 drivers/cpufreq/Kconfig         |   12 +
 drivers/cpufreq/Makefile        |    1 +
 drivers/cpufreq/rcpufreq_dt.rs  |  221 +++++++
 rust/bindings/bindings_helper.h |    2 +
 rust/helpers.c                  |   15 +
 rust/kernel/cpufreq.rs          | 1039 +++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |    4 +
 rust/kernel/opp.rs              |  925 +++++++++++++++++++++++++++
 9 files changed, 2221 insertions(+)
 create mode 100644 drivers/cpufreq/rcpufreq_dt.rs
 create mode 100644 rust/kernel/cpufreq.rs
 create mode 100644 rust/kernel/opp.rs

-- 
2.31.1.272.g89b43f80a514