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 u8, *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 {} 118 119 /// Builder for firmware module info. 120 /// 121 /// [`ModInfoBuilder`] is a helper component to flexibly compose firmware paths strings for the 122 /// .modinfo section in const context. 123 /// 124 /// Therefore the [`ModInfoBuilder`] provides the methods [`ModInfoBuilder::new_entry`] and 125 /// [`ModInfoBuilder::push`], where the latter is used to push path components and the former to 126 /// mark the beginning of a new path string. 127 /// 128 /// [`ModInfoBuilder`] is meant to be used in combination with `kernel::module_firmware!`. 129 /// 130 /// The const generic `N` as well as the `module_name` parameter of [`ModInfoBuilder::new`] is an 131 /// internal implementation detail and supplied through the above macro. 132 pub struct ModInfoBuilder<const N: usize> { 133 buf: [u8; N], 134 n: usize, 135 module_name: &'static CStr, 136 } 137 138 impl<const N: usize> ModInfoBuilder<N> { 139 /// Create an empty builder instance. 140 pub const fn new(module_name: &'static CStr) -> Self { 141 Self { 142 buf: [0; N], 143 n: 0, 144 module_name, 145 } 146 } 147 148 const fn push_internal(mut self, bytes: &[u8]) -> Self { 149 let mut j = 0; 150 151 if N == 0 { 152 self.n += bytes.len(); 153 return self; 154 } 155 156 while j < bytes.len() { 157 if self.n < N { 158 self.buf[self.n] = bytes[j]; 159 } 160 self.n += 1; 161 j += 1; 162 } 163 self 164 } 165 166 /// Push an additional path component. 167 /// 168 /// Append path components to the [`ModInfoBuilder`] instance. Paths need to be separated 169 /// with [`ModInfoBuilder::new_entry`]. 170 /// 171 /// # Example 172 /// 173 /// ``` 174 /// use kernel::firmware::ModInfoBuilder; 175 /// 176 /// # const DIR: &str = "vendor/chip/"; 177 /// # const fn no_run<const N: usize>(builder: ModInfoBuilder<N>) { 178 /// let builder = builder.new_entry() 179 /// .push(DIR) 180 /// .push("foo.bin") 181 /// .new_entry() 182 /// .push(DIR) 183 /// .push("bar.bin"); 184 /// # } 185 /// ``` 186 pub const fn push(self, s: &str) -> Self { 187 // Check whether there has been an initial call to `next_entry()`. 188 if N != 0 && self.n == 0 { 189 crate::build_error!("Must call next_entry() before push()."); 190 } 191 192 self.push_internal(s.as_bytes()) 193 } 194 195 const fn push_module_name(self) -> Self { 196 let mut this = self; 197 let module_name = this.module_name; 198 199 if !this.module_name.is_empty() { 200 this = this.push_internal(module_name.as_bytes_with_nul()); 201 202 if N != 0 { 203 // Re-use the space taken by the NULL terminator and swap it with the '.' separator. 204 this.buf[this.n - 1] = b'.'; 205 } 206 } 207 208 this 209 } 210 211 /// Prepare the [`ModInfoBuilder`] for the next entry. 212 /// 213 /// This method acts as a separator between module firmware path entries. 214 /// 215 /// Must be called before constructing a new entry with subsequent calls to 216 /// [`ModInfoBuilder::push`]. 217 /// 218 /// See [`ModInfoBuilder::push`] for an example. 219 pub const fn new_entry(self) -> Self { 220 self.push_internal(b"\0") 221 .push_module_name() 222 .push_internal(b"firmware=") 223 } 224 225 /// Build the byte array. 226 pub const fn build(self) -> [u8; N] { 227 // Add the final NULL terminator. 228 let this = self.push_internal(b"\0"); 229 230 if this.n == N { 231 this.buf 232 } else { 233 crate::build_error!("Length mismatch."); 234 } 235 } 236 } 237 238 impl ModInfoBuilder<0> { 239 /// Return the length of the byte array to build. 240 pub const fn build_length(self) -> usize { 241 // Compensate for the NULL terminator added by `build`. 242 self.n + 1 243 } 244 } 245