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, ffi, 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(
16 *mut *const bindings::firmware,
17 *const ffi::c_char,
18 *mut bindings::device,
19 ) -> i32,
20);
21
22impl FwFunc {
23 fn request() -> Self {
24 Self(bindings::request_firmware)
25 }
26
27 fn request_nowarn() -> Self {
28 Self(bindings::firmware_request_nowarn)
29 }
30}
31
32/// Abstraction around a C `struct firmware`.
33///
34/// This is a simple abstraction around the C firmware API. Just like with the C API, firmware can
35/// be requested. Once requested the abstraction provides direct access to the firmware buffer as
36/// `&[u8]`. The firmware is released once [`Firmware`] is dropped.
37///
38/// # Invariants
39///
40/// The pointer is valid, and has ownership over the instance of `struct firmware`.
41///
42/// The `Firmware`'s backing buffer is not modified.
43///
44/// # Examples
45///
46/// ```no_run
47/// # use kernel::{c_str, device::Device, firmware::Firmware};
48///
49/// # fn no_run() -> Result<(), Error> {
50/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
51/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
52///
53/// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?;
54/// let blob = fw.data();
55///
56/// # Ok(())
57/// # }
58/// ```
59pub struct Firmware(NonNull<bindings::firmware>);
60
61impl Firmware {
62 fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result<Self> {
63 let mut fw: *mut bindings::firmware = core::ptr::null_mut();
64 let pfw: *mut *mut bindings::firmware = &mut fw;
65
66 // SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer.
67 // `name` and `dev` are valid as by their type invariants.
68 let ret = unsafe { func.0(pfw as _, name.as_char_ptr(), dev.as_raw()) };
69 if ret != 0 {
70 return Err(Error::from_errno(ret));
71 }
72
73 // SAFETY: `func` not bailing out with a non-zero error code, guarantees that `fw` is a
74 // valid pointer to `bindings::firmware`.
75 Ok(Firmware(unsafe { NonNull::new_unchecked(fw) }))
76 }
77
78 /// Send a firmware request and wait for it. See also `bindings::request_firmware`.
79 pub fn request(name: &CStr, dev: &Device) -> Result<Self> {
80 Self::request_internal(name, dev, FwFunc::request())
81 }
82
83 /// Send a request for an optional firmware module. See also
84 /// `bindings::firmware_request_nowarn`.
85 pub fn request_nowarn(name: &CStr, dev: &Device) -> Result<Self> {
86 Self::request_internal(name, dev, FwFunc::request_nowarn())
87 }
88
89 fn as_raw(&self) -> *mut bindings::firmware {
90 self.0.as_ptr()
91 }
92
93 /// Returns the size of the requested firmware in bytes.
94 pub fn size(&self) -> usize {
95 // SAFETY: `self.as_raw()` is valid by the type invariant.
96 unsafe { (*self.as_raw()).size }
97 }
98
99 /// Returns the requested firmware as `&[u8]`.
100 pub fn data(&self) -> &[u8] {
101 // SAFETY: `self.as_raw()` is valid by the type invariant. Additionally,
102 // `bindings::firmware` guarantees, if successfully requested, that
103 // `bindings::firmware::data` has a size of `bindings::firmware::size` bytes.
104 unsafe { core::slice::from_raw_parts((*self.as_raw()).data, self.size()) }
105 }
106}
107
108impl Drop for Firmware {
109 fn drop(&mut self) {
110 // SAFETY: `self.as_raw()` is valid by the type invariant.
111 unsafe { bindings::release_firmware(self.as_raw()) };
112 }
113}
114
115// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, which is safe to be used from
116// any thread.
117unsafe impl Send for Firmware {}
118
119// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to
120// be used from any thread.
121unsafe impl Sync for Firmware {}
122
123/// Create firmware .modinfo entries.
124///
125/// This macro is the counterpart of the C macro `MODULE_FIRMWARE()`, but instead of taking a
126/// simple string literals, which is already covered by the `firmware` field of
127/// [`crate::prelude::module!`], it allows the caller to pass a builder type, based on the
128/// [`ModInfoBuilder`], which can create the firmware modinfo strings in a more flexible way.
129///
130/// Drivers should extend the [`ModInfoBuilder`] with their own driver specific builder type.
131///
132/// The `builder` argument must be a type which implements the following function.
133///
134/// `const fn create(module_name: &'static CStr) -> ModInfoBuilder`
135///
136/// `create` should pass the `module_name` to the [`ModInfoBuilder`] and, with the help of
137/// it construct the corresponding firmware modinfo.
138///
139/// Typically, such contracts would be enforced by a trait, however traits do not (yet) support
140/// const functions.
141///
142/// # Example
143///
144/// ```
145/// # mod module_firmware_test {
146/// # use kernel::firmware;
147/// # use kernel::prelude::*;
148/// #
149/// # struct MyModule;
150/// #
151/// # impl kernel::Module for MyModule {
152/// # fn init(_module: &'static ThisModule) -> Result<Self> {
153/// # Ok(Self)
154/// # }
155/// # }
156/// #
157/// #
158/// struct Builder<const N: usize>;
159///
160/// impl<const N: usize> Builder<N> {
161/// const DIR: &'static str = "vendor/chip/";
162/// const FILES: [&'static str; 3] = [ "foo", "bar", "baz" ];
163///
164/// const fn create(module_name: &'static kernel::str::CStr) -> firmware::ModInfoBuilder<N> {
165/// let mut builder = firmware::ModInfoBuilder::new(module_name);
166///
167/// let mut i = 0;
168/// while i < Self::FILES.len() {
169/// builder = builder.new_entry()
170/// .push(Self::DIR)
171/// .push(Self::FILES[i])
172/// .push(".bin");
173///
174/// i += 1;
175/// }
176///
177/// builder
178/// }
179/// }
180///
181/// module! {
182/// type: MyModule,
183/// name: "module_firmware_test",
184/// author: "Rust for Linux",
185/// description: "module_firmware! test module",
186/// license: "GPL",
187/// }
188///
189/// kernel::module_firmware!(Builder);
190/// # }
191/// ```
192#[macro_export]
193macro_rules! module_firmware {
194 // The argument is the builder type without the const generic, since it's deferred from within
195 // this macro. Hence, we can neither use `expr` nor `ty`.
196 ($($builder:tt)*) => {
197 const _: () = {
198 const __MODULE_FIRMWARE_PREFIX: &'static $crate::str::CStr = if cfg!(MODULE) {
199 $crate::c_str!("")
200 } else {
201 <LocalModule as $crate::ModuleMetadata>::NAME
202 };
203
204 #[link_section = ".modinfo"]
205 #[used]
206 static __MODULE_FIRMWARE: [u8; $($builder)*::create(__MODULE_FIRMWARE_PREFIX)
207 .build_length()] = $($builder)*::create(__MODULE_FIRMWARE_PREFIX).build();
208 };
209 };
210}
211
212/// Builder for firmware module info.
213///
214/// [`ModInfoBuilder`] is a helper component to flexibly compose firmware paths strings for the
215/// .modinfo section in const context.
216///
217/// Therefore the [`ModInfoBuilder`] provides the methods [`ModInfoBuilder::new_entry`] and
218/// [`ModInfoBuilder::push`], where the latter is used to push path components and the former to
219/// mark the beginning of a new path string.
220///
221/// [`ModInfoBuilder`] is meant to be used in combination with [`kernel::module_firmware!`].
222///
223/// The const generic `N` as well as the `module_name` parameter of [`ModInfoBuilder::new`] is an
224/// internal implementation detail and supplied through the above macro.
225pub struct ModInfoBuilder<const N: usize> {
226 buf: [u8; N],
227 n: usize,
228 module_name: &'static CStr,
229}
230
231impl<const N: usize> ModInfoBuilder<N> {
232 /// Create an empty builder instance.
233 pub const fn new(module_name: &'static CStr) -> Self {
234 Self {
235 buf: [0; N],
236 n: 0,
237 module_name,
238 }
239 }
240
241 const fn push_internal(mut self, bytes: &[u8]) -> Self {
242 let mut j = 0;
243
244 if N == 0 {
245 self.n += bytes.len();
246 return self;
247 }
248
249 while j < bytes.len() {
250 if self.n < N {
251 self.buf[self.n] = bytes[j];
252 }
253 self.n += 1;
254 j += 1;
255 }
256 self
257 }
258
259 /// Push an additional path component.
260 ///
261 /// Append path components to the [`ModInfoBuilder`] instance. Paths need to be separated
262 /// with [`ModInfoBuilder::new_entry`].
263 ///
264 /// # Example
265 ///
266 /// ```
267 /// use kernel::firmware::ModInfoBuilder;
268 ///
269 /// # const DIR: &str = "vendor/chip/";
270 /// # const fn no_run<const N: usize>(builder: ModInfoBuilder<N>) {
271 /// let builder = builder.new_entry()
272 /// .push(DIR)
273 /// .push("foo.bin")
274 /// .new_entry()
275 /// .push(DIR)
276 /// .push("bar.bin");
277 /// # }
278 /// ```
279 pub const fn push(self, s: &str) -> Self {
280 // Check whether there has been an initial call to `next_entry()`.
281 if N != 0 && self.n == 0 {
282 crate::build_error!("Must call next_entry() before push().");
283 }
284
285 self.push_internal(s.as_bytes())
286 }
287
288 const fn push_module_name(self) -> Self {
289 let mut this = self;
290 let module_name = this.module_name;
291
292 if !this.module_name.is_empty() {
293 this = this.push_internal(module_name.as_bytes_with_nul());
294
295 if N != 0 {
296 // Re-use the space taken by the NULL terminator and swap it with the '.' separator.
297 this.buf[this.n - 1] = b'.';
298 }
299 }
300
301 this
302 }
303
304 /// Prepare the [`ModInfoBuilder`] for the next entry.
305 ///
306 /// This method acts as a separator between module firmware path entries.
307 ///
308 /// Must be called before constructing a new entry with subsequent calls to
309 /// [`ModInfoBuilder::push`].
310 ///
311 /// See [`ModInfoBuilder::push`] for an example.
312 pub const fn new_entry(self) -> Self {
313 self.push_internal(b"\0")
314 .push_module_name()
315 .push_internal(b"firmware=")
316 }
317
318 /// Build the byte array.
319 pub const fn build(self) -> [u8; N] {
320 // Add the final NULL terminator.
321 let this = self.push_internal(b"\0");
322
323 if this.n == N {
324 this.buf
325 } else {
326 crate::build_error!("Length mismatch.");
327 }
328 }
329}
330
331impl ModInfoBuilder<0> {
332 /// Return the length of the byte array to build.
333 pub const fn build_length(self) -> usize {
334 // Compensate for the NULL terminator added by `build`.
335 self.n + 1
336 }
337}
338

source code of linux/rust/kernel/firmware.rs

Morty Proxy This is a proxified and sanitized view of the page, visit original site.