118 lines · rust
1// SPDX-License-Identifier: GPL-2.02 3//! Firmware abstraction4//!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/// # Invariants11///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 can31/// be requested. Once requested the abstraction provides direct access to the firmware buffer as32/// `&[u8]`. The firmware is released once [`Firmware`] is dropped.33///34/// # Invariants35///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/// # Examples41///42/// ```no_run43/// # 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>` instance47/// # 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 a70 // 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 also80 /// `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, that99 // `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 from112// 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 to116// be used from any thread.117unsafe impl Sync for Firmware {}118