// SPDX-License-Identifier: GPL-2.0 //! Firmware abstraction//!//! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h) use crate::{    bindings,    device::Device,    error::Error,    error::Result,    ffi,    str::{CStr, CStrExt as _},};use core::ptr::NonNull; /// # Invariants////// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`,/// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`.struct FwFunc(    unsafe extern "C" fn(        *mut *const bindings::firmware,        *const ffi::c_char,        *mut bindings::device,    ) -> i32,); impl FwFunc {    fn request() -> Self {        Self(bindings::request_firmware)    }     fn request_nowarn() -> Self {        Self(bindings::firmware_request_nowarn)    }} /// Abstraction around a C `struct firmware`.////// This is a simple abstraction around the C firmware API. Just like with the C API, firmware can/// be requested. Once requested the abstraction provides direct access to the firmware buffer as/// `&[u8]`. The firmware is released once [`Firmware`] is dropped.////// # Invariants////// The pointer is valid, and has ownership over the instance of `struct firmware`.////// The `Firmware`'s backing buffer is not modified.////// # Examples////// ```no_run/// # use kernel::{device::Device, firmware::Firmware};////// # fn no_run() -> Result<(), Error> {/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };////// let fw = Firmware::request(c"path/to/firmware.bin", &dev)?;/// let blob = fw.data();////// # Ok(())/// # }/// ```pub struct Firmware(NonNull<bindings::firmware>); impl Firmware {    fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result<Self> {        let mut fw: *mut bindings::firmware = core::ptr::null_mut();        let pfw: *mut *mut bindings::firmware = &mut fw;        let pfw: *mut *const bindings::firmware = pfw.cast();         // SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer.        // `name` and `dev` are valid as by their type invariants.        let ret = unsafe { func.0(pfw, name.as_char_ptr(), dev.as_raw()) };        if ret != 0 {            return Err(Error::from_errno(ret));        }         // SAFETY: `func` not bailing out with a non-zero error code, guarantees that `fw` is a        // valid pointer to `bindings::firmware`.        Ok(Firmware(unsafe { NonNull::new_unchecked(fw) }))    }     /// Send a firmware request and wait for it. See also `bindings::request_firmware`.    pub fn request(name: &CStr, dev: &Device) -> Result<Self> {        Self::request_internal(name, dev, FwFunc::request())    }     /// Send a request for an optional firmware module. See also    /// `bindings::firmware_request_nowarn`.    pub fn request_nowarn(name: &CStr, dev: &Device) -> Result<Self> {        Self::request_internal(name, dev, FwFunc::request_nowarn())    }     fn as_raw(&self) -> *mut bindings::firmware {        self.0.as_ptr()    }     /// Returns the size of the requested firmware in bytes.    pub fn size(&self) -> usize {        // SAFETY: `self.as_raw()` is valid by the type invariant.        unsafe { (*self.as_raw()).size }    }     /// Returns the requested firmware as `&[u8]`.    pub fn data(&self) -> &[u8] {        // SAFETY: `self.as_raw()` is valid by the type invariant. Additionally,        // `bindings::firmware` guarantees, if successfully requested, that        // `bindings::firmware::data` has a size of `bindings::firmware::size` bytes.        unsafe { core::slice::from_raw_parts((*self.as_raw()).data, self.size()) }    }} impl Drop for Firmware {    fn drop(&mut self) {        // SAFETY: `self.as_raw()` is valid by the type invariant.        unsafe { bindings::release_firmware(self.as_raw()) };    }} // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, which is safe to be used from// any thread.unsafe impl Send for Firmware {} // SAFETY: `Firmware` only holds a pointer to a C `struct firmware`, references to which are safe to// be used from any thread.unsafe impl Sync for Firmware {} /// Create firmware .modinfo entries.////// This macro is the counterpart of the C macro `MODULE_FIRMWARE()`, but instead of taking a/// simple string literals, which is already covered by the `firmware` field of/// [`crate::prelude::module!`], it allows the caller to pass a builder type, based on the/// [`ModInfoBuilder`], which can create the firmware modinfo strings in a more flexible way.////// Drivers should extend the [`ModInfoBuilder`] with their own driver specific builder type.////// The `builder` argument must be a type which implements the following function.////// `const fn create(module_name: &'static CStr) -> ModInfoBuilder`////// `create` should pass the `module_name` to the [`ModInfoBuilder`] and, with the help of/// it construct the corresponding firmware modinfo.////// Typically, such contracts would be enforced by a trait, however traits do not (yet) support/// const functions.////// # Examples////// ```/// # mod module_firmware_test {/// # use kernel::firmware;/// # use kernel::prelude::*;/// #/// # struct MyModule;/// #/// # impl kernel::Module for MyModule {/// #     fn init(_module: &'static ThisModule) -> Result<Self> {/// #         Ok(Self)/// #     }/// # }/// #/// #/// struct Builder<const N: usize>;////// impl<const N: usize> Builder<N> {///     const DIR: &'static str = "vendor/chip/";///     const FILES: [&'static str; 3] = [ "foo", "bar", "baz" ];//////     const fn create(module_name: &'static kernel::str::CStr) -> firmware::ModInfoBuilder<N> {///         let mut builder = firmware::ModInfoBuilder::new(module_name);//////         let mut i = 0;///         while i < Self::FILES.len() {///             builder = builder.new_entry()///                 .push(Self::DIR)///                 .push(Self::FILES[i])///                 .push(".bin");//////                 i += 1;///         }//////         builder///      }/// }////// module! {///    type: MyModule,///    name: "module_firmware_test",///    authors: ["Rust for Linux"],///    description: "module_firmware! test module",///    license: "GPL",/// }////// kernel::module_firmware!(Builder);/// # }/// ```#[macro_export]macro_rules! module_firmware {    // The argument is the builder type without the const generic, since it's deferred from within    // this macro. Hence, we can neither use `expr` nor `ty`.    ($($builder:tt)*) => {        const _: () = {            const __MODULE_FIRMWARE_PREFIX: &'static $crate::str::CStr = if cfg!(MODULE) {                c""            } else {                <LocalModule as $crate::ModuleMetadata>::NAME            };             #[link_section = ".modinfo"]            #[used(compiler)]            static __MODULE_FIRMWARE: [u8; $($builder)*::create(__MODULE_FIRMWARE_PREFIX)                .build_length()] = $($builder)*::create(__MODULE_FIRMWARE_PREFIX).build();        };    };} /// Builder for firmware module info.////// [`ModInfoBuilder`] is a helper component to flexibly compose firmware paths strings for the/// .modinfo section in const context.////// Therefore the [`ModInfoBuilder`] provides the methods [`ModInfoBuilder::new_entry`] and/// [`ModInfoBuilder::push`], where the latter is used to push path components and the former to/// mark the beginning of a new path string.////// [`ModInfoBuilder`] is meant to be used in combination with [`kernel::module_firmware!`].////// The const generic `N` as well as the `module_name` parameter of [`ModInfoBuilder::new`] is an/// internal implementation detail and supplied through the above macro.pub struct ModInfoBuilder<const N: usize> {    buf: [u8; N],    n: usize,    module_name: &'static CStr,} impl<const N: usize> ModInfoBuilder<N> {    /// Create an empty builder instance.    pub const fn new(module_name: &'static CStr) -> Self {        Self {            buf: [0; N],            n: 0,            module_name,        }    }     const fn push_internal(mut self, bytes: &[u8]) -> Self {        let mut j = 0;         if N == 0 {            self.n += bytes.len();            return self;        }         while j < bytes.len() {            if self.n < N {                self.buf[self.n] = bytes[j];            }            self.n += 1;            j += 1;        }        self    }     /// Push an additional path component.    ///    /// Append path components to the [`ModInfoBuilder`] instance. Paths need to be separated    /// with [`ModInfoBuilder::new_entry`].    ///    /// # Examples    ///    /// ```    /// use kernel::firmware::ModInfoBuilder;    ///    /// # const DIR: &str = "vendor/chip/";    /// # const fn no_run<const N: usize>(builder: ModInfoBuilder<N>) {    /// let builder = builder.new_entry()    ///     .push(DIR)    ///     .push("foo.bin")    ///     .new_entry()    ///     .push(DIR)    ///     .push("bar.bin");    /// # }    /// ```    pub const fn push(self, s: &str) -> Self {        // Check whether there has been an initial call to `next_entry()`.        if N != 0 && self.n == 0 {            crate::build_error!("Must call next_entry() before push().");        }         self.push_internal(s.as_bytes())    }     const fn push_module_name(self) -> Self {        let mut this = self;        let module_name = this.module_name;         if !this.module_name.is_empty() {            this = this.push_internal(module_name.to_bytes_with_nul());             if N != 0 {                // Re-use the space taken by the NULL terminator and swap it with the '.' separator.                this.buf[this.n - 1] = b'.';            }        }         this    }     /// Prepare the [`ModInfoBuilder`] for the next entry.    ///    /// This method acts as a separator between module firmware path entries.    ///    /// Must be called before constructing a new entry with subsequent calls to    /// [`ModInfoBuilder::push`].    ///    /// See [`ModInfoBuilder::push`] for an example.    pub const fn new_entry(self) -> Self {        self.push_internal(b"\0")            .push_module_name()            .push_internal(b"firmware=")    }     /// Build the byte array.    pub const fn build(self) -> [u8; N] {        // Add the final NULL terminator.        let this = self.push_internal(b"\0");         if this.n == N {            this.buf        } else {            crate::build_error!("Length mismatch.");        }    }} impl ModInfoBuilder<0> {    /// Return the length of the byte array to build.    pub const fn build_length(self) -> usize {        // Compensate for the NULL terminator added by `build`.        self.n + 1    }}