From: Igor Korotin <igor.korotin.linux@gmail.com>
Date: Fri, 20 Jun 2025 15:24:25 +0000 (+0100)
Subject: rust: acpi: add `acpi::DeviceId` abstraction
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a74931eb59cf6b914e1b9471d9abd4429176f6af;p=thirdparty%2Fkernel%2Fstable.git

rust: acpi: add `acpi::DeviceId` abstraction

`acpi::DeviceId` is an abstraction around `struct acpi_device_id`.

Enable drivers to build ACPI device ID tables, to be consumed by the
corresponding bus abstractions, such as platform or I2C.

Signed-off-by: Igor Korotin <igor.korotin.linux@gmail.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20250620152425.285683-1-igor.korotin.linux@gmail.com
[ Always inline DeviceId::new() and use &'static CStr; slightly reword
  commit message. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---

diff --git a/MAINTAINERS b/MAINTAINERS
index ac68531befed..7f8ddeec3b17 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -302,6 +302,7 @@ F:	include/linux/acpi.h
 F:	include/linux/fwnode.h
 F:	include/linux/fw_table.h
 F:	lib/fw_table.c
+F:	rust/kernel/acpi.rs
 F:	tools/power/acpi/
 
 ACPI APEI
diff --git a/rust/kernel/acpi.rs b/rust/kernel/acpi.rs
new file mode 100644
index 000000000000..eaae3bc8e54c
--- /dev/null
+++ b/rust/kernel/acpi.rs
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Advanced Configuration and Power Interface abstractions.
+
+use crate::{bindings, device_id::RawDeviceId, prelude::*};
+
+/// IdTable type for ACPI drivers.
+pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
+
+/// An ACPI device id.
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct DeviceId(bindings::acpi_device_id);
+
+// SAFETY:
+// * `DeviceId` is a `#[repr(transparent)` wrapper of `struct acpi_device_id` and does not add
+//   additional invariants, so it's safe to transmute to `RawType`.
+// * `DRIVER_DATA_OFFSET` is the offset to the `data` field.
+unsafe impl RawDeviceId for DeviceId {
+    type RawType = bindings::acpi_device_id;
+
+    const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::acpi_device_id, driver_data);
+
+    fn index(&self) -> usize {
+        self.0.driver_data as _
+    }
+}
+
+impl DeviceId {
+    const ACPI_ID_LEN: usize = 16;
+
+    /// Create a new device id from an ACPI 'id' string.
+    #[inline(always)]
+    pub const fn new(id: &'static CStr) -> Self {
+        build_assert!(
+            id.len_with_nul() <= Self::ACPI_ID_LEN,
+            "ID exceeds 16 bytes"
+        );
+        let src = id.as_bytes_with_nul();
+        // Replace with `bindings::acpi_device_id::default()` once stabilized for `const`.
+        // SAFETY: FFI type is valid to be zero-initialized.
+        let mut acpi: bindings::acpi_device_id = unsafe { core::mem::zeroed() };
+        let mut i = 0;
+        while i < src.len() {
+            acpi.id[i] = src[i];
+            i += 1;
+        }
+
+        Self(acpi)
+    }
+}
+
+/// Create an ACPI `IdTable` with an "alias" for modpost.
+#[macro_export]
+macro_rules! acpi_device_table {
+    ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
+        const $table_name: $crate::device_id::IdArray<
+            $crate::acpi::DeviceId,
+            $id_info_type,
+            { $table_data.len() },
+        > = $crate::device_id::IdArray::new($table_data);
+
+        $crate::module_device_table!("acpi", $module_table_name, $table_name);
+    };
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 6b4774b2b1c3..5bbf3627212f 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -51,6 +51,7 @@ extern crate self as kernel;
 
 pub use ffi;
 
+pub mod acpi;
 pub mod alloc;
 #[cfg(CONFIG_AUXILIARY_BUS)]
 pub mod auxiliary;