[PATCH V8 00/14] Rust bindings for cpufreq and OPP core + sample driver

Viresh Kumar
2025-02-06T09:28:54Z

Hello,

I am seeking a few Acks for this patch series before merging it into the PM tree
for the 6.15 merge window, unless there are any objections.

This 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. It also includes minimal bindings for the clk and
cpumask frameworks, which are required by the cpufreq bindings.

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

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

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

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

This version is rebased on v6.14-rc1.

--
Viresh

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

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

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

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

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

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

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

Thanks.

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

Viresh Kumar (13):
cpufreq: Use enum for cpufreq flags that use BIT()
rust: cpu: Add from_cpu()
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

MAINTAINERS | 6 +
drivers/cpufreq/Kconfig | 12 +
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/rcpufreq_dt.rs | 238 +++++++
include/linux/cpufreq.h | 96 +--
rust/bindings/bindings_helper.h | 5 +
rust/helpers/cpufreq.c | 10 +
rust/helpers/cpumask.c | 40 ++
rust/helpers/helpers.c | 2 +
rust/kernel/clk.rs | 48 ++
rust/kernel/cpu.rs | 31 +
rust/kernel/cpufreq.rs | 1054 +++++++++++++++++++++++++++++++
rust/kernel/cpumask.rs | 138 ++++
rust/kernel/lib.rs | 8 +
rust/kernel/opp.rs | 889 ++++++++++++++++++++++++++
rust/macros/module.rs | 17 +-
16 files changed, 2543 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

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2.31.1.272.g89b43f80a514