Re: [PATCH V8 06/14] rust: Add bare minimal bindings for clk framework

Danilo Krummrich
2025-02-06T11:49:14Z

On Thu, Feb 06, 2025 at 02:58:27PM +0530, Viresh Kumar wrote:
> 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>
> ---
> MAINTAINERS | 1 +
> rust/bindings/bindings_helper.h | 1 +
> rust/kernel/clk.rs | 48 +++++++++++++++++++++++++++++++++
> rust/kernel/lib.rs | 2 ++
> 4 files changed, 52 insertions(+)
> create mode 100644 rust/kernel/clk.rs
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ff4511914e0a..604717065476 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5780,6 +5780,7 @@ F: include/dt-bindings/clock/
> F: include/linux/clk-pr*
> F: include/linux/clk/
> F: include/linux/of_clk.h
> +F: rust/kernel/clk.rs
> X: drivers/clk/clkdev.c
>
> COMMON INTERNET FILE SYSTEM CLIENT (CIFS and SMB3)
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index 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);

Guess this should be Opaque<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 ccbf7fa087a0..77d3b1f82154 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -40,6 +40,8 @@
> pub mod block;
> #[doc(hidden)]
> pub mod build_assert;
> +#[cfg(CONFIG_COMMON_CLK)]
> +pub mod clk;
> pub mod cpu;
> pub mod cpumask;
> pub mod cred;
> --
> 2.31.1.272.g89b43f80a514
>
>