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, 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(*mut *const bindings::firmware, *const u8, *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 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/// ```
 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 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
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 from
112// 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 to
116// be used from any thread.
117unsafe impl Sync for Firmware {}