[PATCH v5 12/16] rust: of: add `of::DeviceId` abstraction

Danilo Krummrich
2024-12-10T22:51:15Z

`of::DeviceId` is an abstraction around `struct of_device_id`.

This is used by subsequent patches, in particular the platform bus
abstractions, to create OF device ID tables.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
MAINTAINERS | 1 +
rust/kernel/lib.rs | 1 +
rust/kernel/of.rs | 60 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 62 insertions(+)
create mode 100644 rust/kernel/of.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index 50995e0e4252..7371ab484139 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17502,6 +17502,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
F: Documentation/ABI/testing/sysfs-firmware-ofw
F: drivers/of/
F: include/linux/of*.h
+F: rust/kernel/of.rs
F: scripts/dtc/
F: tools/testing/selftests/dt/
K: of_overlay_notifier_
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 07770add5ee2..7a0e4c82ad0c 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -56,6 +56,7 @@
pub mod miscdevice;
#[cfg(CONFIG_NET)]
pub mod net;
+pub mod of;
pub mod page;
pub mod pid_namespace;
pub mod prelude;
diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
new file mode 100644
index 000000000000..04f2d8ef29cb
--- /dev/null
+++ b/rust/kernel/of.rs
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Device Tree / Open Firmware abstractions.
+
+use crate::{bindings, device_id::RawDeviceId, prelude::*};
+
+/// IdTable type for OF drivers.
+pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
+
+/// An open firmware device id.
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct DeviceId(bindings::of_device_id);
+
+// SAFETY:
+// * `DeviceId` is a `#[repr(transparent)` wrapper of `struct of_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::of_device_id;
+
+ const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::of_device_id, data);
+
+ fn index(&self) -> usize {
+ self.0.data as _
+ }
+}
+
+impl DeviceId {
+ /// Create a new device id from an OF 'compatible' string.
+ pub const fn new(compatible: &'static CStr) -> Self {
+ let src = compatible.as_bytes_with_nul();
+ // Replace with `bindings::of_device_id::default()` once stabilized for `const`.
+ // SAFETY: FFI type is valid to be zero-initialized.
+ let mut of: bindings::of_device_id = unsafe { core::mem::zeroed() };
+
+ // TODO: Use `clone_from_slice` once the corresponding types do match.
+ let mut i = 0;
+ while i < src.len() {
+ of.compatible[i] = src[i] as _;
+ i += 1;
+ }
+
+ Self(of)
+ }
+}
+
+/// Create an OF `IdTable` with an "alias" for modpost.
+#[macro_export]
+macro_rules! of_device_table {
+ ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
+ const $table_name: $crate::device_id::IdArray<
+ $crate::of::DeviceId,
+ $id_info_type,
+ { $table_data.len() },
+ > = $crate::device_id::IdArray::new($table_data);
+
+ $crate::module_device_table!("of", $module_table_name, $table_name);
+ };
+}
--
2.47.0