[PATCH v2 3/5] rust: driver: Add ACPI id table support to Adapter trait

[Igor Korotin <igor.korotin.linux@gmail.com>]

Extend the `Adapter` trait to support ACPI device identification.

This mirrors the existing Open Firmware (OF) support (`of_id_table`) and
enables Rust drivers to match and retrieve ACPI-specific device data
when `CONFIG_ACPI` is enabled.

To avoid breaking compilation, a stub implementation of `acpi_id_table()`
is added to the Platform adapter; the full implementation will be provided
in a subsequent patch.
---
 rust/bindings/bindings_helper.h |  1 +
 rust/kernel/driver.rs           | 58 ++++++++++++++++++++++++++++++---
 rust/kernel/platform.rs         |  5 +++
 3 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index e0bcd130b494..d974fc6c141f 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -6,6 +6,7 @@
  * Sorted alphabetically.
  */
 
+#include <linux/acpi.h>
 #include <kunit/test.h>
 #include <linux/blk-mq.h>
 #include <linux/blk_types.h>
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index ec9166cedfa7..d4098596188a 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -6,7 +6,7 @@
 //! register using the [`Registration`] class.
 
 use crate::error::{Error, Result};
-use crate::{device, of, str::CStr, try_pin_init, types::Opaque, ThisModule};
+use crate::{device, of, acpi, str::CStr, try_pin_init, types::Opaque, ThisModule};
 use core::pin::Pin;
 use pin_init::{pin_data, pinned_drop, PinInit};
 
@@ -141,6 +141,38 @@ pub trait Adapter {
     /// The type holding driver private data about each device id supported by the driver.
     type IdInfo: 'static;
 
+    /// The [`acpi::IdTable`] of the corresponding driver
+    fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>>;
+
+    /// Returns the driver's private data from the matching entry in the [`acpi::IdTable`], if any.
+    ///
+    /// If this returns `None`, it means there is no match with an entry in the [`acpi::IdTable`].
+    #[cfg(CONFIG_ACPI)]
+    fn acpi_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+        let table = Self::acpi_id_table()?;
+
+        // SAFETY:
+        // - `table` has static lifetime, hence it's valid for read,
+        // - `dev` is guaranteed to be valid while it's alive, and so is `pdev.as_ref().as_raw()`.
+        let raw_id = unsafe { bindings::acpi_match_device(table.as_ptr(), dev.as_raw()) };
+
+        if raw_id.is_null() {
+            None
+        } else {
+            // SAFETY: `DeviceId` is a `#[repr(transparent)` wrapper of `struct of_device_id` and
+            // does not add additional invariants, so it's safe to transmute.
+            let id = unsafe { &*raw_id.cast::<acpi::DeviceId>() };
+
+            Some(table.info(<acpi::DeviceId as crate::device_id::RawDeviceId>::index(id)))
+        }
+    }
+
+    #[cfg(not(CONFIG_ACPI))]
+    #[allow(missing_docs)]
+    fn acpi_id_info(_dev: &device::Device) -> Option<&'static Self::IdInfo> {
+        None
+    }
+
     /// The [`of::IdTable`] of the corresponding driver.
     fn of_id_table() -> Option<of::IdTable<Self::IdInfo>>;
 
@@ -178,9 +210,27 @@ fn of_id_info(_dev: &device::Device) -> Option<&'static Self::IdInfo> {
     /// If this returns `None`, it means that there is no match in any of the ID tables directly
     /// associated with a [`device::Device`].
     fn id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
-        let id = Self::of_id_info(dev);
-        if id.is_some() {
-            return id;
+        // SAFETY: `id_info` is called from `Adapter::probe_callback` with a valid `dev` argument.
+        let fwnode = unsafe{ (*dev.as_raw()).fwnode};
+
+        // SAFETY: `bindings::is_acpi_device_node` checks `fwnode` before accessing `fwnode->ops`,
+        // and only compares it with the address of `acpi_device_fwnode_ops`.
+        if unsafe { bindings::is_acpi_device_node(fwnode) } {
+            let id = Self::acpi_id_info(dev);
+
+            if id.is_some() {
+                return id;
+            }
+        }
+
+        // SAFETY: `bindings::is_of_node` checks `fwnode` before accessing `fwnode->ops`,
+        // and only compares it with the address of `of_fwnode_ops`.
+        if unsafe { bindings::is_of_node(fwnode) } {
+            let id = Self::of_id_info(dev);
+
+            if id.is_some() {
+                return id;
+            }
         }
 
         None
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index fd4a494f30e8..3cc9fe6ccfcf 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -5,6 +5,7 @@
 //! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)
 
 use crate::{
+    acpi,
     bindings, device, driver,
     error::{to_result, Result},
     of,
@@ -95,6 +96,10 @@ impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
     fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
         T::OF_ID_TABLE
     }
+
+    fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> {
+        None
+    }
 }
 
 /// Declares a kernel module that exposes a single platform driver.
-- 
2.43.0