Re: [RFC PATCH v1 2/4] rust: add device wakeup support

["Danilo Krummrich" <dakr@kernel.org>]

(Cc: Greg, Rafael)

On Sun Jan 4, 2026 at 7:06 AM CET, Ke Sun wrote:
> diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
> index c79be2e2bfe38..c064111a24531 100644
> --- a/rust/kernel/device.rs
> +++ b/rust/kernel/device.rs
> @@ -325,6 +325,41 @@ pub fn drvdata<T: 'static>(&self) -> Result<Pin<&T>> {
>          // - We've just checked that the type of the driver's private data is in fact `T`.
>          Ok(unsafe { self.drvdata_unchecked() })
>      }
> +
> +    /// Initialize device wakeup capability.
> +    ///
> +    /// Marks the device as wakeup-capable and enables wakeup. The wakeup capability is
> +    /// automatically disabled when the device is removed (resource-managed).

Let's use "when the device is unbound". While "remove" is a common term for this
as well, I prefer "unbind" since it is less ambiguous in this context.

> +    ///
> +    /// Returns `Ok(())` on success, or an error code on failure.
> +    pub fn init_wakeup(&self) -> Result {

Please call this devm_init_wakeup().

> +        // SAFETY: `self.as_raw()` is a valid pointer to a `struct device`.
> +        // The function is exported from bindings_helper module via pub use.
> +        let ret = unsafe { bindings::devm_device_init_wakeup(self.as_raw()) };
> +        if ret != 0 {
> +            return Err(Error::from_errno(ret));
> +        }
> +        Ok(())

Please use to_result() instead.

> +    }
> +
> +    /// Set a device interrupt as a wake IRQ.
> +    ///
> +    /// Attaches the interrupt `irq` as a wake IRQ for this device. The wake IRQ is
> +    /// automatically configured for wake-up from suspend. Must be called after
> +    /// [`Device::init_wakeup`].
> +    ///
> +    /// Returns `Ok(())` on success, or an error code on failure.
> +    pub fn set_wake_irq(&self, irq: i32) -> Result {

The irq argument should be a new type holding the irq number and a
&'a Device<Bound>, i.e. IrqRequest [1].

Technically, this can also be implemented on IrqRequest directly, this way no
additional check for comparing the device pointers is needed; but the method is
fallible anyways, and it is a bit odd to have this method on IrqRequest, so I'd
abstain from this.

> +        if irq < 0 {
> +            return Err(crate::error::code::EINVAL);

You do not need the full qualified name, just EINVAL should work, but with the
above you don't need any manual irq number validation anyways.

> +        }
> +        // SAFETY: `self.as_raw()` is a valid pointer to a `struct device`.
> +        let ret = unsafe { bindings::dev_pm_set_wake_irq(self.as_raw(), irq) };
> +        if ret != 0 {
> +            return Err(Error::from_errno(ret));
> +        }
> +        Ok(())

Please use to_result() instead.

> +    }
>  }

[1] https://rust.docs.kernel.org/kernel/irq/struct.IrqRequest.html