1 files changed, 118 insertions, 0 deletions
diff --git a/rust/kernel/power.rs b/rust/kernel/power.rs
new file mode 100644
index 000000000000..ef788557b269
--- /dev/null
+++ b/rust/kernel/power.rs
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Power management interfaces.
+//!
+//! C header: [`include/linux/pm.h`](../../../../include/linux/pm.h)
+
+#![allow(dead_code)]
+
+use crate::{bindings, error::from_kernel_result, types::PointerWrapper, Result};
+use core::marker::PhantomData;
+
+/// Corresponds to the kernel's `struct dev_pm_ops`.
+///
+/// It is meant to be implemented by drivers that support power-management operations.
+pub trait Operations {
+    /// The type of the context data stored by the driver on each device.
+    type Data: PointerWrapper + Sync + Send;
+
+    /// Called before the system goes into a sleep state.
+    fn suspend(_data: <Self::Data as PointerWrapper>::Borrowed<'_>) -> Result {
+        Ok(())
+    }
+
+    /// Called after the system comes back from a sleep state.
+    fn resume(_data: <Self::Data as PointerWrapper>::Borrowed<'_>) -> Result {
+        Ok(())
+    }
+
+    /// Called before creating a hibernation image.
+    fn freeze(_data: <Self::Data as PointerWrapper>::Borrowed<'_>) -> Result {
+        Ok(())
+    }
+
+    /// Called after the system is restored from a hibernation image.
+    fn restore(_data: <Self::Data as PointerWrapper>::Borrowed<'_>) -> Result {
+        Ok(())
+    }
+}
+
+macro_rules! pm_callback {
+    ($callback:ident, $method:ident) => {
+        unsafe extern "C" fn $callback<T: Operations>(
+            dev: *mut bindings::device,
+        ) -> core::ffi::c_int {
+            from_kernel_result! {
+                // SAFETY: `dev` is valid as it was passed in by the C portion.
+                let ptr = unsafe { bindings::dev_get_drvdata(dev) };
+                // SAFETY: By the safety requirements of `OpsTable::build`, we know that `ptr` came
+                // from a previous call to `T::Data::into_pointer`.
+                let data = unsafe { T::Data::borrow(ptr) };
+                T::$method(data)?;
+                Ok(0)
+            }
+        }
+    };
+}
+
+pm_callback!(suspend_callback, suspend);
+pm_callback!(resume_callback, resume);
+pm_callback!(freeze_callback, freeze);
+pm_callback!(restore_callback, restore);
+
+pub(crate) struct OpsTable<T: Operations>(PhantomData<*const T>);
+
+impl<T: Operations> OpsTable<T> {
+    const VTABLE: bindings::dev_pm_ops = bindings::dev_pm_ops {
+        prepare: None,
+        complete: None,
+        suspend: Some(suspend_callback::<T>),
+        resume: Some(resume_callback::<T>),
+        freeze: Some(freeze_callback::<T>),
+        thaw: None,
+        poweroff: None,
+        restore: Some(restore_callback::<T>),
+        suspend_late: None,
+        resume_early: None,
+        freeze_late: None,
+        thaw_early: None,
+        poweroff_late: None,
+        restore_early: None,
+        suspend_noirq: None,
+        resume_noirq: None,
+        freeze_noirq: None,
+        thaw_noirq: None,
+        poweroff_noirq: None,
+        restore_noirq: None,
+        runtime_suspend: None,
+        runtime_resume: None,
+        runtime_idle: None,
+    };
+
+    /// Builds an instance of `struct dev_pm_ops`.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `dev_get_drvdata` will result in a value returned by
+    /// [`T::Data::into_pointer`].
+    pub(crate) const unsafe fn build() -> &'static bindings::dev_pm_ops {
+        &Self::VTABLE
+    }
+}
+
+/// Implements the [`Operations`] trait as no-ops.
+///
+/// This is useful when one doesn't want to provide the implementation of any power-manager related
+/// operation.
+pub struct NoOperations<T: PointerWrapper>(PhantomData<T>);
+
+impl<T: PointerWrapper + Send + Sync> Operations for NoOperations<T> {
+    type Data = T;
+}
+
+// SAFETY: `NoOperation` provides no functionality, it is safe to send a reference to it to
+// different threads.
+unsafe impl<T: PointerWrapper> Sync for NoOperations<T> {}
+
+// SAFETY: `NoOperation` provides no functionality, it is safe to send it to different threads.
+unsafe impl<T: PointerWrapper> Send for NoOperations<T> {}