1 // SPDX-License-Identifier: GPL-2.0
2 
3 //! Device Tree / Open Firmware abstractions.
4 
5 use crate::{bindings, device_id::RawDeviceId, prelude::*};
6 
7 /// IdTable type for OF drivers.
8 pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
9 
10 /// An open firmware device id.
11 #[repr(transparent)]
12 #[derive(Clone, Copy)]
13 pub struct DeviceId(bindings::of_device_id);
14 
15 // SAFETY:
16 // * `DeviceId` is a `#[repr(transparent)` wrapper of `struct of_device_id` and does not add
17 //   additional invariants, so it's safe to transmute to `RawType`.
18 // * `DRIVER_DATA_OFFSET` is the offset to the `data` field.
19 unsafe impl RawDeviceId for DeviceId {
20     type RawType = bindings::of_device_id;
21 
22     const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::of_device_id, data);
23 
index(&self) -> usize24     fn index(&self) -> usize {
25         self.0.data as _
26     }
27 }
28 
29 impl DeviceId {
30     /// Create a new device id from an OF 'compatible' string.
new(compatible: &'static CStr) -> Self31     pub const fn new(compatible: &'static CStr) -> Self {
32         let src = compatible.as_bytes_with_nul();
33         // Replace with `bindings::of_device_id::default()` once stabilized for `const`.
34         // SAFETY: FFI type is valid to be zero-initialized.
35         let mut of: bindings::of_device_id = unsafe { core::mem::zeroed() };
36 
37         // TODO: Use `clone_from_slice` once the corresponding types do match.
38         let mut i = 0;
39         while i < src.len() {
40             of.compatible[i] = src[i] as _;
41             i += 1;
42         }
43 
44         Self(of)
45     }
46 }
47 
48 /// Create an OF `IdTable` with an "alias" for modpost.
49 #[macro_export]
50 macro_rules! of_device_table {
51     ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
52         const $table_name: $crate::device_id::IdArray<
53             $crate::of::DeviceId,
54             $id_info_type,
55             { $table_data.len() },
56         > = $crate::device_id::IdArray::new($table_data);
57 
58         $crate::module_device_table!("of", $module_table_name, $table_name);
59     };
60 }
61