1 files changed, 63 insertions, 0 deletions
diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
new file mode 100644
index 000000000000..cdcd83244337
--- /dev/null
+++ b/rust/kernel/of.rs
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Devicetree and Open Firmware abstractions.
+//!
+//! C header: [`include/linux/of_*.h`](../../../../include/linux/of_*.h)
+
+use crate::{bindings, driver, str::BStr};
+
+/// An open firmware device id.
+#[derive(Clone, Copy)]
+pub enum DeviceId {
+    /// An open firmware device id where only a compatible string is specified.
+    Compatible(&'static BStr),
+}
+
+/// Defines a const open firmware device id table that also carries per-entry data/context/info.
+///
+/// The name of the const is `OF_DEVICE_ID_TABLE`, which is what buses are expected to name their
+/// open firmware tables.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::define_of_id_table;
+/// use kernel::of;
+///
+/// define_of_id_table! {u32, [
+///     (of::DeviceId::Compatible(b"test-device1,test-device2"), Some(0xff)),
+///     (of::DeviceId::Compatible(b"test-device3"), None),
+/// ]};
+/// ```
+#[macro_export]
+macro_rules! define_of_id_table {
+    ($data_type:ty, $($t:tt)*) => {
+        $crate::define_id_table!(OF_DEVICE_ID_TABLE, $crate::of::DeviceId, $data_type, $($t)*);
+    };
+}
+
+// SAFETY: `ZERO` is all zeroed-out and `to_rawid` stores `offset` in `of_device_id::data`.
+unsafe impl const driver::RawDeviceId for DeviceId {
+    type RawType = bindings::of_device_id;
+    const ZERO: Self::RawType = bindings::of_device_id {
+        name: [0; 32],
+        type_: [0; 32],
+        compatible: [0; 128],
+        data: core::ptr::null(),
+    };
+
+    fn to_rawid(&self, offset: isize) -> Self::RawType {
+        let DeviceId::Compatible(compatible) = self;
+        let mut id = Self::ZERO;
+        let mut i = 0;
+        while i < compatible.len() {
+            // If `compatible` does not fit in `id.compatible`, an "index out of bounds" build time
+            // error will be triggered.
+            id.compatible[i] = compatible[i] as _;
+            i += 1;
+        }
+        id.compatible[i] = b'\0' as _;
+        id.data = offset as _;
+        id
+    }
+}