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1// SPDX-License-Identifier: GPL-2.0
2
3//! Commonly used sizes.
4//!
5//! C headers: [`include/linux/sizes.h`](srctree/include/linux/sizes.h).
6//!
7//! The top-level `SZ_*` constants are [`usize`]-typed, for use in kernel page
8//! arithmetic and similar CPU-side work.
9//!
10//! The [`SizeConstants`] trait provides the same constants as associated constants
11//! on [`u32`], [`u64`], and [`usize`], for use in device address spaces where
12//! the address width depends on the hardware. Device drivers frequently need
13//! these constants as [`u64`] (or [`u32`]) rather than [`usize`], because
14//! device address spaces are sized independently of the CPU pointer width.
15//!
16//! # Examples
17//!
18//! ```
19//! use kernel::{
20//! page::PAGE_SIZE,
21//! sizes::{
22//! SizeConstants,
23//! SZ_1M, //
24//! }, //
25//! };
26//!
27//! // Module-level constants continue to work without a type qualifier.
28//! let num_pages_in_1m = SZ_1M / PAGE_SIZE;
29//!
30//! // Trait associated constants require a type qualifier.
31//! let heap_size = 14 * u64::SZ_1M;
32//! let small = u32::SZ_4K;
33//! ```
34
35macro_rules! define_sizes {
36 ($($type:ty),* $(,)?) => {
37 define_sizes!(@internal [$($type),*]
38 /// `0x0000_0400`.
39 SZ_1K,
40 /// `0x0000_0800`.
41 SZ_2K,
42 /// `0x0000_1000`.
43 SZ_4K,
44 /// `0x0000_2000`.
45 SZ_8K,
46 /// `0x0000_4000`.
47 SZ_16K,
48 /// `0x0000_8000`.
49 SZ_32K,
50 /// `0x0001_0000`.
51 SZ_64K,
52 /// `0x0002_0000`.
53 SZ_128K,
54 /// `0x0004_0000`.
55 SZ_256K,
56 /// `0x0008_0000`.
57 SZ_512K,
58 /// `0x0010_0000`.
59 SZ_1M,
60 /// `0x0020_0000`.
61 SZ_2M,
62 /// `0x0040_0000`.
63 SZ_4M,
64 /// `0x0080_0000`.
65 SZ_8M,
66 /// `0x0100_0000`.
67 SZ_16M,
68 /// `0x0200_0000`.
69 SZ_32M,
70 /// `0x0400_0000`.
71 SZ_64M,
72 /// `0x0800_0000`.
73 SZ_128M,
74 /// `0x1000_0000`.
75 SZ_256M,
76 /// `0x2000_0000`.
77 SZ_512M,
78 /// `0x4000_0000`.
79 SZ_1G,
80 /// `0x8000_0000`.
81 SZ_2G,
82 );
83 };
84
85 (@internal [$($type:ty),*] $($names_and_metas:tt)*) => {
86 define_sizes!(@consts_and_trait $($names_and_metas)*);
87 define_sizes!(@impls [$($type),*] $($names_and_metas)*);
88 };
89
90 (@consts_and_trait $($(#[$meta:meta])* $name:ident,)*) => {
91 $(
92 $(#[$meta])*
93 pub const $name: usize = bindings::$name as usize;
94 )*
95
96 /// Size constants for device address spaces.
97 ///
98 /// Implemented for [`u32`], [`u64`], and [`usize`] so drivers can
99 /// choose the width that matches their hardware. All `SZ_*` values fit
100 /// in a [`u32`], so all implementations are lossless.
101 ///
102 /// # Examples
103 ///
104 /// ```
105 /// use kernel::sizes::SizeConstants;
106 ///
107 /// let gpu_heap = 14 * u64::SZ_1M;
108 /// let mmio_window = u32::SZ_16M;
109 /// ```
110 pub trait SizeConstants {
111 $(
112 $(#[$meta])*
113 const $name: Self;
114 )*
115 }
116 };
117
118 (@impls [] $($(#[$meta:meta])* $name:ident,)*) => {};
119
120 (@impls [$first:ty $(, $rest:ty)*] $($(#[$meta:meta])* $name:ident,)*) => {
121 impl SizeConstants for $first {
122 $(
123 const $name: Self = {
124 assert!((self::$name as u128) <= (<$first>::MAX as u128));
125 self::$name as $first
126 };
127 )*
128 }
129
130 define_sizes!(@impls [$($rest),*] $($(#[$meta])* $name,)*);
131 };
132}
133
134define_sizes!(u32, u64, usize);