These accessors can be used to retrieve a irq::Registration and
irq::ThreadedRegistration from a platform device by
index or name. Alternatively, drivers can retrieve an IrqRequest from a
bound platform device for later use.

These accessors ensure that only valid IRQ lines can ever be registered.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
 rust/kernel/platform.rs | 146 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 145 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index ced43367d900bcb87c0ce1af3981f5e5af129840..ba334bfdaf1db4cb60a33ef275739958bc4c77d5 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -5,8 +5,11 @@
 //! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)
 
 use crate::{
-    acpi, bindings, container_of, device, driver,
+    acpi, bindings, container_of,
+    device::{self, Bound},
+    driver,
     error::{from_result, to_result, Result},
+    irq::{self, IrqRequest},
     of,
     prelude::*,
     types::Opaque,
@@ -226,6 +229,147 @@ fn as_raw(&self) -> *mut bindings::platform_device {
     }
 }
 
+macro_rules! define_irq_accessor_by_index {
+    ($(#[$meta:meta])* $fn_name:ident, $request_fn:ident, $reg_type:ident, $handler_trait:ident) => {
+        $(#[$meta])*
+        pub fn $fn_name<T: irq::$handler_trait + 'static>(
+            &self,
+            flags: irq::flags::Flags,
+            index: u32,
+            name: &'static CStr,
+            handler: T,
+        ) -> Result<impl PinInit<irq::$reg_type<T>, Error> + '_> {
+            let request = self.$request_fn(index)?;
+
+            Ok(irq::$reg_type::<T>::new(
+                request,
+                flags,
+                name,
+                handler,
+            ))
+        }
+    };
+}
+
+macro_rules! define_irq_accessor_by_name {
+    ($(#[$meta:meta])* $fn_name:ident, $request_fn:ident, $reg_type:ident, $handler_trait:ident) => {
+        $(#[$meta])*
+        pub fn $fn_name<T: irq::$handler_trait + 'static>(
+            &self,
+            flags: irq::flags::Flags,
+            irq_name: &CStr,
+            name: &'static CStr,
+            handler: T,
+        ) -> Result<impl PinInit<irq::$reg_type<T>, Error> + '_> {
+            let request = self.$request_fn(irq_name)?;
+
+            Ok(irq::$reg_type::<T>::new(
+                request,
+                flags,
+                name,
+                handler,
+            ))
+        }
+    };
+}
+
+impl Device<Bound> {
+    /// Returns an [`IrqRequest`] for the IRQ at the given index, if any.
+    pub fn irq_by_index(&self, index: u32) -> Result<IrqRequest<'_>> {
+        // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`.
+        let irq = unsafe { bindings::platform_get_irq(self.as_raw(), index) };
+
+        if irq < 0 {
+            return Err(Error::from_errno(irq));
+        }
+
+        // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`.
+        Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) })
+    }
+
+    /// Returns an [`IrqRequest`] for the IRQ at the given index, but does not
+    /// print an error if the IRQ cannot be obtained.
+    pub fn optional_irq_by_index(&self, index: u32) -> Result<IrqRequest<'_>> {
+        // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`.
+        let irq = unsafe { bindings::platform_get_irq_optional(self.as_raw(), index) };
+
+        if irq < 0 {
+            return Err(Error::from_errno(irq));
+        }
+
+        // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`.
+        Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) })
+    }
+
+    /// Returns an [`IrqRequest`] for the IRQ with the given name, if any.
+    pub fn irq_by_name(&self, name: &CStr) -> Result<IrqRequest<'_>> {
+        // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`.
+        let irq = unsafe { bindings::platform_get_irq_byname(self.as_raw(), name.as_char_ptr()) };
+
+        if irq < 0 {
+            return Err(Error::from_errno(irq));
+        }
+
+        // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`.
+        Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) })
+    }
+
+    /// Returns an [`IrqRequest`] for the IRQ with the given name, but does not
+    /// print an error if the IRQ cannot be obtained.
+    pub fn optional_irq_by_name(&self, name: &CStr) -> Result<IrqRequest<'_>> {
+        // SAFETY: `self.as_raw` returns a valid pointer to a `struct platform_device`.
+        let irq = unsafe {
+            bindings::platform_get_irq_byname_optional(self.as_raw(), name.as_char_ptr())
+        };
+
+        if irq < 0 {
+            return Err(Error::from_errno(irq));
+        }
+
+        // SAFETY: `irq` is guaranteed to be a valid IRQ number for `&self`.
+        Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) })
+    }
+
+    define_irq_accessor_by_index!(
+        /// Returns a [`irq::Registration`] for the IRQ at the given index.
+        request_irq_by_index, irq_by_index, Registration, Handler
+    );
+    define_irq_accessor_by_name!(
+        /// Returns a [`irq::Registration`] for the IRQ with the given name.
+        request_irq_by_name, irq_by_name, Registration, Handler
+    );
+    define_irq_accessor_by_index!(
+        /// Does the same as [`Self::request_irq_by_index`], except that it does
+        /// not print an error message if the IRQ cannot be obtained.
+        request_optional_irq_by_index, optional_irq_by_index, Registration, Handler
+    );
+    define_irq_accessor_by_name!(
+        /// Does the same as [`Self::request_irq_by_name`], except that it does
+        /// not print an error message if the IRQ cannot be obtained.
+        request_optional_irq_by_name, optional_irq_by_name, Registration, Handler
+    );
+
+    define_irq_accessor_by_index!(
+        /// Returns a [`irq::ThreadedRegistration`] for the IRQ at the given index.
+        request_threaded_irq_by_index, irq_by_index, ThreadedRegistration, ThreadedHandler
+    );
+    define_irq_accessor_by_name!(
+        /// Returns a [`irq::ThreadedRegistration`] for the IRQ with the given name.
+        request_threaded_irq_by_name, irq_by_name, ThreadedRegistration, ThreadedHandler
+    );
+    define_irq_accessor_by_index!(
+        /// Does the same as [`Self::request_threaded_irq_by_index`], except
+        /// that it does not print an error message if the IRQ cannot be
+        /// obtained.
+        request_optional_threaded_irq_by_index, optional_irq_by_index, ThreadedRegistration, ThreadedHandler
+    );
+    define_irq_accessor_by_name!(
+        /// Does the same as [`Self::request_threaded_irq_by_name`], except that
+        /// it does not print an error message if the IRQ cannot be obtained.
+        request_optional_threaded_irq_by_name, optional_irq_by_name, ThreadedRegistration, ThreadedHandler
+    );
+}
+
 // SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
 // argument.
 kernel::impl_device_context_deref!(unsafe { Device });

-- 
2.50.0