1 files changed, 42 insertions, 30 deletions

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index c97d6d470b28..8435f8132e38 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -6,7 +6,7 @@
 
 use crate::{
     alloc::flags::*,
-    bindings, device,
+    bindings, container_of, device,
     device_id::RawDeviceId,
     devres::Devres,
     driver,
@@ -89,7 +89,7 @@ impl<T: Driver + 'static> Adapter<T> {
     extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
         // SAFETY: The PCI bus only ever calls the remove callback with a valid pointer to a
         // `struct pci_dev`.
-        let ptr = unsafe { bindings::pci_get_drvdata(pdev) };
+        let ptr = unsafe { bindings::pci_get_drvdata(pdev) }.cast();
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
@@ -118,7 +118,9 @@ macro_rules! module_pci_driver {
 };
 }
 
-/// Abstraction for bindings::pci_device_id.
+/// Abstraction for the PCI device ID structure ([`struct pci_device_id`]).
+///
+/// [`struct pci_device_id`]: https://docs.kernel.org/PCI/pci.html#c.pci_device_id
 #[repr(transparent)]
 #[derive(Clone, Copy)]
 pub struct DeviceId(bindings::pci_device_id);
@@ -173,7 +175,7 @@ unsafe impl RawDeviceId for DeviceId {
     }
 }
 
-/// IdTable type for PCI
+/// `IdTable` type for PCI.
 pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
 
 /// Create a PCI `IdTable` with its alias for modpost.
@@ -224,10 +226,11 @@ macro_rules! pci_device_table {
 /// `Adapter` documentation for an example.
 pub trait Driver: Send {
     /// The type holding information about each device id supported by the driver.
-    ///
-    /// TODO: Use associated_type_defaults once stabilized:
-    ///
-    /// type IdInfo: 'static = ();
+    // TODO: Use `associated_type_defaults` once stabilized:
+    //
+    // ```
+    // type IdInfo: 'static = ();
+    // ```
     type IdInfo: 'static;
 
     /// The table of device ids supported by the driver.
@@ -360,11 +363,13 @@ impl<const SIZE: usize> Deref for Bar<SIZE> {
     }
 }
 
-impl Device {
+impl<Ctx: device::DeviceContext> Device<Ctx> {
     fn as_raw(&self) -> *mut bindings::pci_dev {
         self.0.get()
     }
+}
 
+impl Device {
     /// Returns the PCI vendor ID.
     pub fn vendor_id(&self) -> u16 {
         // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
@@ -388,7 +393,9 @@ impl Device {
         // - by its type invariant `self.as_raw` is always a valid pointer to a `struct pci_dev`.
         Ok(unsafe { bindings::pci_resource_len(self.as_raw(), bar.try_into()?) })
     }
+}
 
+impl Device<device::Bound> {
     /// Mapps an entire PCI-BAR after performing a region-request on it. I/O operation bound checks
     /// can be performed on compile time for offsets (plus the requested type size) < SIZE.
     pub fn iomap_region_sized<const SIZE: usize>(
@@ -422,25 +429,10 @@ impl Device<device::Core> {
     }
 }
 
-impl Deref for Device<device::Core> {
-    type Target = Device;
-
-    fn deref(&self) -> &Self::Target {
-        let ptr: *const Self = self;
-
-        // CAST: `Device<Ctx>` is a transparent wrapper of `Opaque<bindings::pci_dev>`.
-        let ptr = ptr.cast::<Device>();
-
-        // SAFETY: `ptr` was derived from `&self`.
-        unsafe { &*ptr }
-    }
-}
-
-impl From<&Device<device::Core>> for ARef<Device> {
-    fn from(dev: &Device<device::Core>) -> Self {
-        (&**dev).into()
-    }
-}
+// 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 });
+kernel::impl_device_context_into_aref!(Device);
 
 // SAFETY: Instances of `Device` are always reference-counted.
 unsafe impl crate::types::AlwaysRefCounted for Device {
@@ -455,8 +447,8 @@ unsafe impl crate::types::AlwaysRefCounted for Device {
     }
 }
 
-impl AsRef<device::Device> for Device {
-    fn as_ref(&self) -> &device::Device {
+impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {
+    fn as_ref(&self) -> &device::Device<Ctx> {
         // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
         // `struct pci_dev`.
         let dev = unsafe { addr_of_mut!((*self.as_raw()).dev) };
@@ -466,6 +458,26 @@ impl AsRef<device::Device> for Device {
     }
 }
 
+impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &Device<Ctx> {
+    type Error = kernel::error::Error;
+
+    fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {
+        // SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a
+        // `struct device`.
+        if !unsafe { bindings::dev_is_pci(dev.as_raw()) } {
+            return Err(EINVAL);
+        }
+
+        // SAFETY: We've just verified that the bus type of `dev` equals `bindings::pci_bus_type`,
+        // hence `dev` must be embedded in a valid `struct pci_dev` as guaranteed by the
+        // corresponding C code.
+        let pdev = unsafe { container_of!(dev.as_raw(), bindings::pci_dev, dev) };
+
+        // SAFETY: `pdev` is a valid pointer to a `struct pci_dev`.
+        Ok(unsafe { &*pdev.cast() })
+    }
+}
+
 // SAFETY: A `Device` is always reference-counted and can be released from any thread.
 unsafe impl Send for Device {}