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// SPDX-License-Identifier: GPL-2.0
//! Commonly used sizes.
//!
//! C headers: [`include/linux/sizes.h`](srctree/include/linux/sizes.h).
//!
//! The top-level `SZ_*` constants are [`usize`]-typed, for use in kernel page
//! arithmetic and similar CPU-side work.
//!
//! The [`SizeConstants`] trait provides the same constants as associated constants
//! on [`u32`], [`u64`], and [`usize`], for use in device address spaces where
//! the address width depends on the hardware. Device drivers frequently need
//! these constants as [`u64`] (or [`u32`]) rather than [`usize`], because
//! device address spaces are sized independently of the CPU pointer width.
//!
//! # Examples
//!
//! ```
//! use kernel::{
//! page::PAGE_SIZE,
//! sizes::{
//! SizeConstants,
//! SZ_1M, //
//! }, //
//! };
//!
//! // Module-level constants continue to work without a type qualifier.
//! let num_pages_in_1m = SZ_1M / PAGE_SIZE;
//!
//! // Trait associated constants require a type qualifier.
//! let heap_size = 14 * u64::SZ_1M;
//! let small = u32::SZ_4K;
//! ```
macro_rules! define_sizes {
($($type:ty),* $(,)?) => {
define_sizes!(@internal [$($type),*]
/// `0x0000_0400`.
SZ_1K,
/// `0x0000_0800`.
SZ_2K,
/// `0x0000_1000`.
SZ_4K,
/// `0x0000_2000`.
SZ_8K,
/// `0x0000_4000`.
SZ_16K,
/// `0x0000_8000`.
SZ_32K,
/// `0x0001_0000`.
SZ_64K,
/// `0x0002_0000`.
SZ_128K,
/// `0x0004_0000`.
SZ_256K,
/// `0x0008_0000`.
SZ_512K,
/// `0x0010_0000`.
SZ_1M,
/// `0x0020_0000`.
SZ_2M,
/// `0x0040_0000`.
SZ_4M,
/// `0x0080_0000`.
SZ_8M,
/// `0x0100_0000`.
SZ_16M,
/// `0x0200_0000`.
SZ_32M,
/// `0x0400_0000`.
SZ_64M,
/// `0x0800_0000`.
SZ_128M,
/// `0x1000_0000`.
SZ_256M,
/// `0x2000_0000`.
SZ_512M,
/// `0x4000_0000`.
SZ_1G,
/// `0x8000_0000`.
SZ_2G,
);
};
(@internal [$($type:ty),*] $($names_and_metas:tt)*) => {
define_sizes!(@consts_and_trait $($names_and_metas)*);
define_sizes!(@impls [$($type),*] $($names_and_metas)*);
};
(@consts_and_trait $($(#[$meta:meta])* $name:ident,)*) => {
$(
$(#[$meta])*
pub const $name: usize = bindings::$name as usize;
)*
/// Size constants for device address spaces.
///
/// Implemented for [`u32`], [`u64`], and [`usize`] so drivers can
/// choose the width that matches their hardware. All `SZ_*` values fit
/// in a [`u32`], so all implementations are lossless.
///
/// # Examples
///
/// ```
/// use kernel::sizes::SizeConstants;
///
/// let gpu_heap = 14 * u64::SZ_1M;
/// let mmio_window = u32::SZ_16M;
/// ```
pub trait SizeConstants {
$(
$(#[$meta])*
const $name: Self;
)*
}
};
(@impls [] $($(#[$meta:meta])* $name:ident,)*) => {};
(@impls [$first:ty $(, $rest:ty)*] $($(#[$meta:meta])* $name:ident,)*) => {
impl SizeConstants for $first {
$(
const $name: Self = {
assert!((self::$name as u128) <= (<$first>::MAX as u128));
self::$name as $first
};
)*
}
define_sizes!(@impls [$($rest),*] $($(#[$meta])* $name,)*);
};
}
define_sizes!(u32, u64, usize);