[PATCH v4 2/3] rust: clk: add devres-managed clks

[Daniel Almeida]

The clk API allows fine-grained control, but some drivers might be
more interested in a "set and forget" API.

Expand the current API to support this. The clock will automatically be
disabled, unprepared and freed when the device is unbound from the bus
without further intervention by the driver.

Signed-off-by: Daniel Almeida <daniel.almeida at collabora.com>
---
 rust/kernel/clk.rs | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
index a62e4c7e252e..692ee88ca772 100644
--- a/rust/kernel/clk.rs
+++ b/rust/kernel/clk.rs
@@ -95,6 +95,49 @@ impl Sealed for super::Prepared {}
         impl Sealed for super::Enabled {}
     }
 
+    /// Obtains and enables a [`devres`]-managed [`Clk`] for a bound device.
+    ///
+    /// [`devres`]: crate::devres::Devres
+    pub fn devm_enable(dev: &Device<Bound>, name: Option<&CStr>) -> Result {
+        let name = name.map_or(ptr::null(), |n| n.as_char_ptr());
+
+        // SAFETY: It is safe to call [`devm_clk_get_enabled`] with a valid
+        // device pointer.
+        from_err_ptr(unsafe { bindings::devm_clk_get_enabled(dev.as_raw(), name) })?;
+        Ok(())
+    }
+
+    /// Obtains and enables a [`devres`]-managed [`Clk`] for a bound device.
+    ///
+    /// This does not print any error messages if the clock is not found.
+    ///
+    /// [`devres`]: crate::devres::Devres
+    pub fn devm_enable_optional(dev: &Device<Bound>, name: Option<&CStr>) -> Result {
+        let name = name.map_or(ptr::null(), |n| n.as_char_ptr());
+
+        // SAFETY: It is safe to call [`devm_clk_get_optional_enabled`] with a
+        // valid device pointer.
+        from_err_ptr(unsafe { bindings::devm_clk_get_optional_enabled(dev.as_raw(), name) })?;
+        Ok(())
+    }
+
+    /// Same as [`devm_enable_optional`], but also sets the rate.
+    pub fn devm_enable_optional_with_rate(
+        dev: &Device<Bound>,
+        name: Option<&CStr>,
+        rate: Hertz,
+    ) -> Result {
+        let name = name.map_or(ptr::null(), |n| n.as_char_ptr());
+
+        // SAFETY: It is safe to call
+        // [`devm_clk_get_optional_enabled_with_rate`] with a valid device
+        // pointer.
+        from_err_ptr(unsafe {
+            bindings::devm_clk_get_optional_enabled_with_rate(dev.as_raw(), name, rate.as_hz())
+        })?;
+        Ok(())
+    }
+
     /// A trait representing the different states that a [`Clk`] can be in.
     pub trait ClkState: private::Sealed {
         /// Whether the clock should be disabled when dropped.

-- 
2.54.0