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Message-ID: <CAH5fLggcPo9g7Ep22aUj+5t+zdUQqa96NopZa946nsN649PQ2g@mail.gmail.com>
Date: Mon, 3 Mar 2025 11:04:24 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>,
Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...nel.org>,
Trevor Gross <tmgross@...ch.edu>, Russell King <linux@...linux.org.uk>, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
Vincent Guittot <vincent.guittot@...aro.org>, Daniel Almeida <daniel.almeida@...labora.com>
Subject: Re: [PATCH V3 2/2] rust: Add initial clk abstractions
On Mon, Mar 3, 2025 at 11:00 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> Add initial abstractions for the clk APIs. These provide the minimal
> functionality needed for common use cases, making them straightforward
> to introduce in the first iteration.
>
> These will be used by Rust based cpufreq / OPP layers to begin with.
>
> Tested-by: Daniel Almeida <daniel.almeida@...labora.com>
> Reviewed-by: Daniel Almeida <daniel.almeida@...labora.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Every function in this patch could be #[inline]. Otherwise rustc will
generate a bunch of wrapper functions that just forward a call into C.
> MAINTAINERS | 1 +
> rust/kernel/clk.rs | 134 +++++++++++++++++++++++++++++++++++++++++++++
> rust/kernel/lib.rs | 1 +
> 3 files changed, 136 insertions(+)
> create mode 100644 rust/kernel/clk.rs
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 726110d3c988..96e2574f41c0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5779,6 +5779,7 @@ F: include/linux/clk-pr*
> F: include/linux/clk/
> F: include/linux/of_clk.h
> F: rust/helpers/clk.c
> +F: rust/kernel/clk.rs
> X: drivers/clk/clkdev.c
>
> COMMON INTERNET FILE SYSTEM CLIENT (CIFS and SMB3)
> diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
> new file mode 100644
> index 000000000000..1fa5b7298373
> --- /dev/null
> +++ b/rust/kernel/clk.rs
> @@ -0,0 +1,134 @@
> +// 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, to_result, Result},
> + prelude::*,
> +};
> +
> +use core::{ops::Deref, ptr};
> +
> +/// Frequency unit.
> +pub type Hertz = crate::ffi::c_ulong;
> +
> +/// A simple implementation of `struct clk` from the C code.
> +#[repr(transparent)]
> +pub struct Clk(*mut bindings::clk);
This needs an invariants section.
> +
> +impl Clk {
> + /// Gets clock corresponding to a device and a connection id and returns `Clk`.
> + pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
> + let con_id = if let Some(name) = name {
> + name.as_ptr() as *const _
> + } else {
> + ptr::null()
> + };
> +
> + // SAFETY: It is safe to call `clk_get()` for a valid device pointer.
> + 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
> + }
> +
> + /// Clock enable.
> + pub fn enable(&self) -> Result<()> {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + to_result(unsafe { bindings::clk_enable(self.as_raw()) })
> + }
> +
> + /// Clock disable.
> + pub fn disable(&self) {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + unsafe { bindings::clk_disable(self.as_raw()) };
> + }
> +
> + /// Clock prepare.
> + pub fn prepare(&self) -> Result<()> {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + to_result(unsafe { bindings::clk_prepare(self.as_raw()) })
> + }
> +
> + /// Clock unprepare.
> + pub fn unprepare(&self) {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + unsafe { bindings::clk_unprepare(self.as_raw()) };
> + }
> +
> + /// Clock prepare enable.
> + pub fn prepare_enable(&self) -> Result<()> {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + to_result(unsafe { bindings::clk_prepare_enable(self.as_raw()) })
> + }
> +
> + /// Clock disable unprepare.
> + pub fn disable_unprepare(&self) {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + unsafe { bindings::clk_disable_unprepare(self.as_raw()) };
> + }
> +
> + /// Clock get rate.
> + pub fn rate(&self) -> Hertz {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + unsafe { bindings::clk_get_rate(self.as_raw()) }
> + }
> +
> + /// Clock set rate.
> + pub fn set_rate(&self, rate: Hertz) -> Result<()> {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + to_result(unsafe { bindings::clk_set_rate(self.as_raw(), rate) })
> + }
> +}
> +
> +impl Drop for Clk {
> + fn drop(&mut self) {
> + // SAFETY: It is safe to call clk APIs of the C code for a clock pointer earlier returned
> + // by `clk_get()`.
> + unsafe { bindings::clk_put(self.as_raw()) };
> + }
> +}
> +
> +/// A simple implementation of optional `Clk`.
> +pub struct OptionalClk(Clk);
What is this?
> +impl OptionalClk {
> + /// Gets optional clock corresponding to a device and a connection id and returns `Clk`.
> + pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
> + let con_id = if let Some(name) = name {
> + name.as_ptr() as *const _
> + } else {
> + ptr::null()
> + };
> +
> + // SAFETY: It is safe to call `clk_get_optional()` for a valid device pointer.
> + Ok(Self(Clk(from_err_ptr(unsafe {
> + bindings::clk_get_optional(dev.as_raw(), con_id)
> + })?)))
> + }
> +}
> +
> +// Make `OptionalClk` behave like `Clk`.
> +impl Deref for OptionalClk {
> + type Target = Clk;
> +
> + fn deref(&self) -> &Clk {
> + &self.0
> + }
> +}
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index 496ed32b0911..324b86f127a0 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -40,6 +40,7 @@
> pub mod block;
> #[doc(hidden)]
> pub mod build_assert;
> +pub mod clk;
> pub mod cred;
> pub mod device;
> pub mod device_id;
> --
> 2.31.1.272.g89b43f80a514
>
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