// SPDX-License-Identifier: GPL-2.0

//! The `kernel` crate.
//!
//! This crate contains the kernel APIs that have been ported or wrapped for
//! usage by Rust code in the kernel and is shared by all of them.
//!
//! In other words, all the rest of the Rust code in the kernel (e.g. kernel
//! modules written in Rust) depends on [`core`], [`alloc`] and this crate.
//!
//! If you need a kernel C API that is not ported or wrapped yet here, then
//! do so first instead of bypassing this crate.

#![no_std]
#![feature(allocator_api)]
#![feature(associated_type_defaults)]
#![feature(coerce_unsized)]
#![feature(const_refs_to_cell)]
#![feature(const_trait_impl)]
#![feature(dispatch_from_dyn)]
#![feature(new_uninit)]
#![feature(receiver_trait)]
#![feature(unsize)]
#![feature(const_mut_refs)]

// Ensure conditional compilation based on the kernel configuration works;
// otherwise we may silently break things like initcall handling.
#[cfg(not(CONFIG_RUST))]
compile_error!("Missing kernel configuration for conditional compilation");

// Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
extern crate self as kernel;

#[cfg(not(test))]
#[cfg(not(testlib))]
mod allocator;
pub mod box_ext;
mod build_assert;
pub mod device;
pub mod dma;
pub mod driver;
pub mod error;
pub mod init;
pub mod io_mem;
pub mod ioctl;
pub mod irq;
#[cfg(CONFIG_KUNIT)]
pub mod kunit;
#[doc(hidden)]
pub mod module_param;
pub mod pages;
pub mod prelude;
pub mod print;
pub mod revocable;
mod static_assert;
#[doc(hidden)]
pub mod std_vendor;
pub mod str;
pub mod sync;
pub mod task;
pub mod types;

#[doc(hidden)]
pub use bindings;
pub use macros;
#[cfg(CONFIG_PCI)]
pub mod pci;
pub use uapi;

#[doc(hidden)]
pub use build_error::build_error;

/// Page size defined in terms of the `PAGE_SHIFT` macro from C.
///
/// [`PAGE_SHIFT`]: ../../../include/asm-generic/page.h
pub const PAGE_SIZE: u32 = 1 << bindings::PAGE_SHIFT;

/// Prefix to appear before log messages printed from within the `kernel` crate.
const __LOG_PREFIX: &[u8] = b"rust_kernel\0";

/// The top level entrypoint to implementing a kernel module.
///
/// For any teardown or cleanup operations, your type may implement [`Drop`].
pub trait Module: Sized + Sync {
    /// Called at module initialization time.
    ///
    /// Use this method to perform whatever setup or registration your module
    /// should do.
    ///
    /// Equivalent to the `module_init` macro in the C API.
    fn init(name: &'static str::CStr, module: &'static ThisModule) -> error::Result<Self>;
}

/// Equivalent to `THIS_MODULE` in the C API.
///
/// C header: `include/linux/export.h`
pub struct ThisModule(*mut bindings::module);

// SAFETY: `THIS_MODULE` may be used from all threads within a module.
unsafe impl Sync for ThisModule {}

impl ThisModule {
    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
    ///
    /// # Safety
    ///
    /// The pointer must be equal to the right `THIS_MODULE`.
    pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
        ThisModule(ptr)
    }
}

#[cfg(not(any(testlib, test)))]
#[panic_handler]
fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
    pr_emerg!("{}\n", info);
    // SAFETY: FFI call.
    unsafe { bindings::BUG() };
}

/// Returns maximum number of CPUs that may be online on the system.
pub fn num_possible_cpus() -> u32 {
    // SAFETY: FFI call with no additional requirements.
    unsafe { bindings::num_possible_cpus() }
}