[RFC PATCH 2/3] rust/platform: Add support for runtime PM

[Beata Michalska <beata.michalska@arm.com>]

Wire the per-driver dev_pm_ops pointer into platform_driver
registration so Rust drivers can expose PM callbacks to the PM core.
Also add a TryFrom implementation from Device<CoreInternal>
to platform::Device so generated PM callbacks can recover
a platform device from the generic device pointer received
from the PM core.

Signed-off-by: Beata Michalska <beata.michalska@arm.com>
---
 rust/kernel/platform.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 8917d4ee499f..d100adc2ef76 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -72,6 +72,11 @@ unsafe fn register(
             None => core::ptr::null(),
         };
 
+        let pm_ops = match T::PM_OPS {
+            Some(ops) => ops,
+            None => core::ptr::null(),
+        };
+
         // SAFETY: It's safe to set the fields of `struct platform_driver` on initialization.
         unsafe {
             (*pdrv.get()).driver.name = name.as_char_ptr();
@@ -79,6 +84,7 @@ unsafe fn register(
             (*pdrv.get()).remove = Some(Self::remove_callback);
             (*pdrv.get()).driver.of_match_table = of_table;
             (*pdrv.get()).driver.acpi_match_table = acpi_table;
+            (*pdrv.get()).driver.pm = pm_ops;
         }
 
         // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
@@ -218,6 +224,9 @@ pub trait Driver: Send {
     /// The table of ACPI device ids supported by the driver.
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;
 
+    /// Runtime PM callbacks
+    const PM_OPS: Option<&'static bindings::dev_pm_ops> = None;
+
     /// Platform driver probe.
     ///
     /// Called when a new platform device is added or discovered.
@@ -555,6 +564,15 @@ fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {
     }
 }
 
+impl TryFrom<&device::Device<device::CoreInternal>> for &Device {
+    type Error = kernel::error::Error;
+
+    fn try_from(dev: &device::Device<device::CoreInternal>) -> Result<Self, Self::Error> {
+        let pdev_ci: &Device<device::CoreInternal> = TryFrom::try_from(dev)?;
+        Ok(pdev_ci)
+    }
+}
+
 // SAFETY: A `Device` is always reference-counted and can be released from any thread.
 unsafe impl Send for Device {}
 
-- 
2.43.0