projects/linux·blob v6.13 · refs

117 lines · 4.1 KiB

1// SPDX-License-Identifier: GPL-2.0
2
3//! Firmware abstraction
4//!
5//! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h)
6
7use crate::{bindings, device::Device, error::Error, error::Result, str::CStr};
8use core::ptr::NonNull;
9
10/// # Invariants
11///
12/// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`,
13/// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`.
14struct FwFunc(
15 unsafe extern "C" fn(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32,
16);
17
18impl FwFunc {
19 fn request() -> Self {
20 Self(bindings::request_firmware)
21 }
22
23 fn request_nowarn() -> Self {
24 Self(bindings::firmware_request_nowarn)
25 }
26}
27
28/// Abstraction around a C `struct firmware`.
29///
30/// This is a simple abstraction around the C firmware API. Just like with the C API, firmware can
31/// be requested. Once requested the abstraction provides direct access to the firmware buffer as
32/// `&[u8]`. The firmware is released once [`Firmware`] is dropped.
33///
34/// # Invariants
35///
36/// The pointer is valid, and has ownership over the instance of `struct firmware`.
37///
38/// The `Firmware`'s backing buffer is not modified.
39///
40/// # Examples
41///
42/// ```no_run
43/// # use kernel::{c_str, device::Device, firmware::Firmware};
44///
45/// # fn no_run() -> Result<(), Error> {
46/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
47/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
48///
49/// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?;
50/// let blob = fw.data();
51///
52/// # Ok(())
53/// # }
54/// ```
55pub struct Firmware(NonNull<bindings::firmware>);
56
57impl Firmware {
58 fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result<Self> {
59 let mut fw: *mut bindings::firmware = core::ptr::null_mut();
60 let pfw: *mut *mut bindings::firmware = &mut fw;
61
62 // SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer.
63 // `name` and `dev` are valid as by their type invariants.
64 let ret = unsafe { func.0(pfw as _, name.as_char_ptr(), dev.as_raw()) };
65 if ret != 0 {
66 return Err(Error::from_errno(ret));
67 }
68
69 // SAFETY: `func` not bailing out with a non-zero error code, guarantees that `fw` is a
70 // valid pointer to `bindings::firmware`.
71 Ok(Firmware(unsafe { NonNull::new_unchecked(fw) }))
72 }
73
74 /// Send a firmware request and wait for it. See also `bindings::request_firmware`.
75 pub fn request(name: &CStr, dev: &Device) -> Result<Self> {
76 Self::request_internal(name, dev, FwFunc::request())
77 }
78
79 /// Send a request for an optional firmware module. See also
80 /// `bindings::firmware_request_nowarn`.
81 pub fn request_nowarn(name: &CStr, dev: &Device) -> Result<Self> {
82 Self::request_internal(name, dev, FwFunc::request_nowarn())
83 }
84
85 fn as_raw(&self) -> *mut bindings::firmware {
86 self.0.as_ptr()
87 }
88
89 /// Returns the size of the requested firmware in bytes.
90 pub fn size(&self) -> usize {
91 // SAFETY: `self.as_raw()` is valid by the type invariant.
92 unsafe { (*self.as_raw()).size }
93 }
94
95 /// Returns the requested firmware as `&[u8]`.
96 pub fn data(&self) -> &[u8] {
97 // SAFETY: `self.as_raw()` is valid by the type invariant. Additionally,
98 // `bindings::firmware` guarantees, if successfully requested, that
99 // `bindings::firmware::data` has a size of `bindings::firmware::size` bytes.
100 unsafe { core::slice::from_raw_parts((*self.as_raw()).data, self.size()) }
101 }
102}
103
104impl Drop for Firmware {
105 fn drop(&mut self) {
106 // SAFETY: `self.as_raw()` is valid by the type invariant.
107 unsafe { bindings::release_firmware(self.as_raw()) };
108 }
109}
110
111// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, which is safe to be used from
112// any thread.
113unsafe impl Send for Firmware {}
114
115// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to
116// be used from any thread.
117unsafe impl Sync for Firmware {}