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2c61b8c51d
The doctests of `Firmware` are compile-time only tests, since they
require a proper `Device` and a valid path to a (firmware) blob in order
to do something sane on runtime - we can't satisfy both of those
requirements.
Hence, configure the example as `no_run`.
Unfortunately, the kernel's Rust build system can't consider the
`no_run` attribute yet. Hence, for the meantime, wrap the example code
into a new function and never actually call it.
Fixes: de6582833d ("rust: add firmware abstractions")
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://lore.kernel.org/r/20240708200724.3203-1-dakr@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
105 lines
3.9 KiB
Rust
105 lines
3.9 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Firmware abstraction
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//!
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//! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h")
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use crate::{bindings, device::Device, error::Error, error::Result, str::CStr};
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use core::ptr::NonNull;
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// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`,
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// `firmware_request_platform`, `bindings::request_firmware_direct`
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type FwFunc =
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unsafe extern "C" fn(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32;
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/// Abstraction around a C `struct firmware`.
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///
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/// This is a simple abstraction around the C firmware API. Just like with the C API, firmware can
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/// be requested. Once requested the abstraction provides direct access to the firmware buffer as
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/// `&[u8]`. The firmware is released once [`Firmware`] is dropped.
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///
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/// # Invariants
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///
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/// The pointer is valid, and has ownership over the instance of `struct firmware`.
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///
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/// The `Firmware`'s backing buffer is not modified.
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///
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/// # Examples
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///
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/// ```no_run
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/// # use kernel::{c_str, device::Device, firmware::Firmware};
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///
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/// # fn no_run() -> Result<(), Error> {
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/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
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/// # let dev = unsafe { Device::from_raw(core::ptr::null_mut()) };
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///
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/// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?;
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/// let blob = fw.data();
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///
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/// # Ok(())
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/// # }
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/// ```
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pub struct Firmware(NonNull<bindings::firmware>);
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impl Firmware {
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fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result<Self> {
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let mut fw: *mut bindings::firmware = core::ptr::null_mut();
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let pfw: *mut *mut bindings::firmware = &mut fw;
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// SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer.
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// `name` and `dev` are valid as by their type invariants.
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let ret = unsafe { func(pfw as _, name.as_char_ptr(), dev.as_raw()) };
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if ret != 0 {
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return Err(Error::from_errno(ret));
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}
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// SAFETY: `func` not bailing out with a non-zero error code, guarantees that `fw` is a
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// valid pointer to `bindings::firmware`.
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Ok(Firmware(unsafe { NonNull::new_unchecked(fw) }))
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}
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/// Send a firmware request and wait for it. See also `bindings::request_firmware`.
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pub fn request(name: &CStr, dev: &Device) -> Result<Self> {
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Self::request_internal(name, dev, bindings::request_firmware)
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}
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/// Send a request for an optional firmware module. See also
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/// `bindings::firmware_request_nowarn`.
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pub fn request_nowarn(name: &CStr, dev: &Device) -> Result<Self> {
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Self::request_internal(name, dev, bindings::firmware_request_nowarn)
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}
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fn as_raw(&self) -> *mut bindings::firmware {
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self.0.as_ptr()
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}
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/// Returns the size of the requested firmware in bytes.
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pub fn size(&self) -> usize {
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// SAFETY: `self.as_raw()` is valid by the type invariant.
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unsafe { (*self.as_raw()).size }
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}
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/// Returns the requested firmware as `&[u8]`.
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pub fn data(&self) -> &[u8] {
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// SAFETY: `self.as_raw()` is valid by the type invariant. Additionally,
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// `bindings::firmware` guarantees, if successfully requested, that
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// `bindings::firmware::data` has a size of `bindings::firmware::size` bytes.
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unsafe { core::slice::from_raw_parts((*self.as_raw()).data, self.size()) }
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}
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}
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impl Drop for Firmware {
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fn drop(&mut self) {
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// SAFETY: `self.as_raw()` is valid by the type invariant.
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unsafe { bindings::release_firmware(self.as_raw()) };
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}
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}
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// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, which is safe to be used from
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// any thread.
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unsafe impl Send for Firmware {}
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// SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to
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// be used from any thread.
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unsafe impl Sync for Firmware {}
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