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

[Danilo Krummrich <dakr@kernel.org>]

On Thu, Feb 06, 2025 at 12:49:14PM +0100, Danilo Krummrich wrote:
> 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>.

Sorry, I meant NonNull<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
> > 
> >