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, 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(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32, 16 ); 17 18 impl 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 /// ``` 55 pub struct Firmware(NonNull<bindings::firmware>); 56 57 impl 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 } 103 104 impl 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. 113 unsafe 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. 117 unsafe impl Sync for Firmware {} 118