linux-kernel - Re: [PATCH V3 2/2] rust: Add initial clk abstractions

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Message-ID: <20250303113259.ybl3i6jfc5bwvk6r@vireshk-i7>
Date: Mon, 3 Mar 2025 17:02:59 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Alice Ryhl <aliceryhl@...gle.com>
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 03-03-25, 11:04, Alice Ryhl wrote:
> > +/// A simple implementation of optional `Clk`.
> > +pub struct OptionalClk(Clk);
> 
> What is this?

This came up during review of the previous version [1]. A resource (clk in this
case) can be optional for a driver to work and such drivers call
clk_get_optional(). Similar APIs are present in other frameworks as well.

I was not sure if this should be implemented as a separate method in struct Clk
itself or like 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)
> > +        })?)))
> > +    }
> > +}

-- 
viresh

[1] https://lore.kernel.org/all/20250221215931.GA134397-robh@kernel.org/