|
| 1 | +// SPDX-License-Identifier: GPL-2.0 |
| 2 | + |
| 3 | +//! Memory-mapped IO. |
| 4 | +//! |
| 5 | +//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h) |
| 6 | +
|
| 7 | +use crate::error::{code::EINVAL, Result}; |
| 8 | +use crate::{bindings, build_assert}; |
| 9 | + |
| 10 | +/// IO-mapped memory, starting at the base address @addr and spanning @maxlen bytes. |
| 11 | +/// |
| 12 | +/// The creator (usually a subsystem such as PCI) is responsible for creating the |
| 13 | +/// mapping, performing an additional region request etc. |
| 14 | +/// |
| 15 | +/// # Invariant |
| 16 | +/// |
| 17 | +/// `addr` is the start and `maxsize` the length of valid I/O remapped memory region. |
| 18 | +/// |
| 19 | +/// # Examples |
| 20 | +/// |
| 21 | +/// ``` |
| 22 | +/// # use kernel::{bindings, io::Io}; |
| 23 | +/// # use core::ops::Deref; |
| 24 | +/// |
| 25 | +/// // See also [`pci::Bar`] for a real example. |
| 26 | +/// struct IoMem<const SIZE: usize>(Io<SIZE>); |
| 27 | +/// |
| 28 | +/// impl<const SIZE: usize> IoMem<SIZE> { |
| 29 | +/// fn new(paddr: usize) -> Result<Self>{ |
| 30 | +/// |
| 31 | +/// // SAFETY: assert safety for this example |
| 32 | +/// let addr = unsafe { bindings::ioremap(paddr as _, SIZE.try_into().unwrap()) }; |
| 33 | +/// if addr.is_null() { |
| 34 | +/// return Err(ENOMEM); |
| 35 | +/// } |
| 36 | +/// |
| 37 | +/// // SAFETY: `addr` is guaranteed to be the start of a valid I/O mapped memory region of |
| 38 | +/// // size `SIZE`. |
| 39 | +/// let io = unsafe { Io::new(addr as _, SIZE)? }; |
| 40 | +/// |
| 41 | +/// Ok(IoMem(io)) |
| 42 | +/// } |
| 43 | +/// } |
| 44 | +/// |
| 45 | +/// impl<const SIZE: usize> Drop for IoMem<SIZE> { |
| 46 | +/// fn drop(&mut self) { |
| 47 | +/// // SAFETY: Safe as by the invariant of `Io`. |
| 48 | +/// unsafe { bindings::iounmap(self.0.base_addr() as _); }; |
| 49 | +/// } |
| 50 | +/// } |
| 51 | +/// |
| 52 | +/// impl<const SIZE: usize> Deref for IoMem<SIZE> { |
| 53 | +/// type Target = Io<SIZE>; |
| 54 | +/// |
| 55 | +/// fn deref(&self) -> &Self::Target { |
| 56 | +/// &self.0 |
| 57 | +/// } |
| 58 | +/// } |
| 59 | +/// |
| 60 | +/// let iomem = IoMem::<{ core::mem::size_of::<u32>() }>::new(0xBAAAAAAD).unwrap(); |
| 61 | +/// iomem.writel(0x42, 0x0); |
| 62 | +/// assert!(iomem.try_writel(0x42, 0x0).is_ok()); |
| 63 | +/// assert!(iomem.try_writel(0x42, 0x4).is_err()); |
| 64 | +/// ``` |
| 65 | +pub struct Io<const SIZE: usize = 0> { |
| 66 | + addr: usize, |
| 67 | + maxsize: usize, |
| 68 | +} |
| 69 | + |
| 70 | +macro_rules! define_read { |
| 71 | + ($(#[$attr:meta])* $name:ident, $try_name:ident, $type_name:ty) => { |
| 72 | + /// Read IO data from a given offset known at compile time. |
| 73 | + /// |
| 74 | + /// Bound checks are performed on compile time, hence if the offset is not known at compile |
| 75 | + /// time, the build will fail. |
| 76 | + $(#[$attr])* |
| 77 | + #[inline] |
| 78 | + pub fn $name(&self, offset: usize) -> $type_name { |
| 79 | + let addr = self.io_addr_assert::<$type_name>(offset); |
| 80 | + |
| 81 | + unsafe { bindings::$name(addr as _) } |
| 82 | + } |
| 83 | + |
| 84 | + /// Read IO data from a given offset. |
| 85 | + /// |
| 86 | + /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is |
| 87 | + /// out of bounds. |
| 88 | + $(#[$attr])* |
| 89 | + pub fn $try_name(&self, offset: usize) -> Result<$type_name> { |
| 90 | + let addr = self.io_addr::<$type_name>(offset)?; |
| 91 | + |
| 92 | + Ok(unsafe { bindings::$name(addr as _) }) |
| 93 | + } |
| 94 | + }; |
| 95 | +} |
| 96 | + |
| 97 | +macro_rules! define_write { |
| 98 | + ($(#[$attr:meta])* $name:ident, $try_name:ident, $type_name:ty) => { |
| 99 | + /// Write IO data from a given offset known at compile time. |
| 100 | + /// |
| 101 | + /// Bound checks are performed on compile time, hence if the offset is not known at compile |
| 102 | + /// time, the build will fail. |
| 103 | + $(#[$attr])* |
| 104 | + #[inline] |
| 105 | + pub fn $name(&self, value: $type_name, offset: usize) { |
| 106 | + let addr = self.io_addr_assert::<$type_name>(offset); |
| 107 | + |
| 108 | + unsafe { bindings::$name(value, addr as _, ) } |
| 109 | + } |
| 110 | + |
| 111 | + /// Write IO data from a given offset. |
| 112 | + /// |
| 113 | + /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is |
| 114 | + /// out of bounds. |
| 115 | + $(#[$attr])* |
| 116 | + pub fn $try_name(&self, value: $type_name, offset: usize) -> Result { |
| 117 | + let addr = self.io_addr::<$type_name>(offset)?; |
| 118 | + |
| 119 | + unsafe { bindings::$name(value, addr as _) } |
| 120 | + Ok(()) |
| 121 | + } |
| 122 | + }; |
| 123 | +} |
| 124 | + |
| 125 | +impl<const SIZE: usize> Io<SIZE> { |
| 126 | + /// |
| 127 | + /// |
| 128 | + /// # Safety |
| 129 | + /// |
| 130 | + /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size |
| 131 | + /// `maxsize`. |
| 132 | + pub unsafe fn new(addr: usize, maxsize: usize) -> Result<Self> { |
| 133 | + if maxsize < SIZE { |
| 134 | + return Err(EINVAL); |
| 135 | + } |
| 136 | + |
| 137 | + Ok(Self { addr, maxsize }) |
| 138 | + } |
| 139 | + |
| 140 | + /// Returns the base address of this mapping. |
| 141 | + #[inline] |
| 142 | + pub fn base_addr(&self) -> usize { |
| 143 | + self.addr |
| 144 | + } |
| 145 | + |
| 146 | + /// Returns the size of this mapping. |
| 147 | + #[inline] |
| 148 | + pub fn maxsize(&self) -> usize { |
| 149 | + self.maxsize |
| 150 | + } |
| 151 | + |
| 152 | + #[inline] |
| 153 | + const fn offset_valid<U>(offset: usize, size: usize) -> bool { |
| 154 | + let type_size = core::mem::size_of::<U>(); |
| 155 | + if let Some(end) = offset.checked_add(type_size) { |
| 156 | + end <= size && offset % type_size == 0 |
| 157 | + } else { |
| 158 | + false |
| 159 | + } |
| 160 | + } |
| 161 | + |
| 162 | + #[inline] |
| 163 | + fn io_addr<U>(&self, offset: usize) -> Result<usize> { |
| 164 | + if !Self::offset_valid::<U>(offset, self.maxsize()) { |
| 165 | + return Err(EINVAL); |
| 166 | + } |
| 167 | + |
| 168 | + // Probably no need to check, since the safety requirements of `Self::new` guarantee that |
| 169 | + // this can't overflow. |
| 170 | + self.base_addr().checked_add(offset).ok_or(EINVAL) |
| 171 | + } |
| 172 | + |
| 173 | + #[inline] |
| 174 | + fn io_addr_assert<U>(&self, offset: usize) -> usize { |
| 175 | + build_assert!(Self::offset_valid::<U>(offset, SIZE)); |
| 176 | + |
| 177 | + self.base_addr() + offset |
| 178 | + } |
| 179 | + |
| 180 | + define_read!(readb, try_readb, u8); |
| 181 | + define_read!(readw, try_readw, u16); |
| 182 | + define_read!(readl, try_readl, u32); |
| 183 | + define_read!( |
| 184 | + #[cfg(CONFIG_64BIT)] |
| 185 | + readq, |
| 186 | + try_readq, |
| 187 | + u64 |
| 188 | + ); |
| 189 | + |
| 190 | + define_read!(readb_relaxed, try_readb_relaxed, u8); |
| 191 | + define_read!(readw_relaxed, try_readw_relaxed, u16); |
| 192 | + define_read!(readl_relaxed, try_readl_relaxed, u32); |
| 193 | + define_read!( |
| 194 | + #[cfg(CONFIG_64BIT)] |
| 195 | + readq_relaxed, |
| 196 | + try_readq_relaxed, |
| 197 | + u64 |
| 198 | + ); |
| 199 | + |
| 200 | + define_write!(writeb, try_writeb, u8); |
| 201 | + define_write!(writew, try_writew, u16); |
| 202 | + define_write!(writel, try_writel, u32); |
| 203 | + define_write!( |
| 204 | + #[cfg(CONFIG_64BIT)] |
| 205 | + writeq, |
| 206 | + try_writeq, |
| 207 | + u64 |
| 208 | + ); |
| 209 | + |
| 210 | + define_write!(writeb_relaxed, try_writeb_relaxed, u8); |
| 211 | + define_write!(writew_relaxed, try_writew_relaxed, u16); |
| 212 | + define_write!(writel_relaxed, try_writel_relaxed, u32); |
| 213 | + define_write!( |
| 214 | + #[cfg(CONFIG_64BIT)] |
| 215 | + writeq_relaxed, |
| 216 | + try_writeq_relaxed, |
| 217 | + u64 |
| 218 | + ); |
| 219 | +} |
0 commit comments