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 7 use crate::{bindings, device::Device, error::Error, error::Result, ffi, str::CStr}; 8 use 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`. 14 struct FwFunc( 15 unsafe extern "C" fn( 16 *mut *const bindings::firmware, 17 *const ffi::c_char, 18 *mut bindings::device, 19 ) -> i32, 20 ); 21 22 impl FwFunc { request() -> Self23 fn request() -> Self { 24 Self(bindings::request_firmware) 25 } 26 request_nowarn() -> Self27 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 /// ``` 59 pub struct Firmware(NonNull<bindings::firmware>); 60 61 impl Firmware { request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result<Self>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`. request(name: &CStr, dev: &Device) -> Result<Self>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`. request_nowarn(name: &CStr, dev: &Device) -> Result<Self>85 pub fn request_nowarn(name: &CStr, dev: &Device) -> Result<Self> { 86 Self::request_internal(name, dev, FwFunc::request_nowarn()) 87 } 88 as_raw(&self) -> *mut bindings::firmware89 fn as_raw(&self) -> *mut bindings::firmware { 90 self.0.as_ptr() 91 } 92 93 /// Returns the size of the requested firmware in bytes. size(&self) -> usize94 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]`. data(&self) -> &[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 } 107 108 impl Drop for Firmware { drop(&mut self)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. 117 unsafe 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. 121 unsafe impl Sync for Firmware {} 122