projects/linux·blob v6.17 · refs

265 lines · 8.6 KiB

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
7use crate::error::{code::EINVAL, Result};
8use crate::{bindings, build_assert, ffi::c_void};
9
10pub mod mem;
11pub mod resource;
12
13pub use resource::Resource;
14
15/// Raw representation of an MMIO region.
16///
17/// By itself, the existence of an instance of this structure does not provide any guarantees that
18/// the represented MMIO region does exist or is properly mapped.
19///
20/// Instead, the bus specific MMIO implementation must convert this raw representation into an `Io`
21/// instance providing the actual memory accessors. Only by the conversion into an `Io` structure
22/// any guarantees are given.
23pub struct IoRaw<const SIZE: usize = 0> {
24 addr: usize,
25 maxsize: usize,
26}
27
28impl<const SIZE: usize> IoRaw<SIZE> {
29 /// Returns a new `IoRaw` instance on success, an error otherwise.
30 pub fn new(addr: usize, maxsize: usize) -> Result<Self> {
31 if maxsize < SIZE {
32 return Err(EINVAL);
33 }
34
35 Ok(Self { addr, maxsize })
36 }
37
38 /// Returns the base address of the MMIO region.
39 #[inline]
40 pub fn addr(&self) -> usize {
41 self.addr
42 }
43
44 /// Returns the maximum size of the MMIO region.
45 #[inline]
46 pub fn maxsize(&self) -> usize {
47 self.maxsize
48 }
49}
50
51/// IO-mapped memory region.
52///
53/// The creator (usually a subsystem / bus such as PCI) is responsible for creating the
54/// mapping, performing an additional region request etc.
55///
56/// # Invariant
57///
58/// `addr` is the start and `maxsize` the length of valid I/O mapped memory region of size
59/// `maxsize`.
60///
61/// # Examples
62///
63/// ```no_run
64/// # use kernel::{bindings, ffi::c_void, io::{Io, IoRaw}};
65/// # use core::ops::Deref;
66///
67/// // See also [`pci::Bar`] for a real example.
68/// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
69///
70/// impl<const SIZE: usize> IoMem<SIZE> {
71/// /// # Safety
72/// ///
73/// /// [`paddr`, `paddr` + `SIZE`) must be a valid MMIO region that is mappable into the CPUs
74/// /// virtual address space.
75/// unsafe fn new(paddr: usize) -> Result<Self>{
76/// // SAFETY: By the safety requirements of this function [`paddr`, `paddr` + `SIZE`) is
77/// // valid for `ioremap`.
78/// let addr = unsafe { bindings::ioremap(paddr as bindings::phys_addr_t, SIZE) };
79/// if addr.is_null() {
80/// return Err(ENOMEM);
81/// }
82///
83/// Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
84/// }
85/// }
86///
87/// impl<const SIZE: usize> Drop for IoMem<SIZE> {
88/// fn drop(&mut self) {
89/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`.
90/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };
91/// }
92/// }
93///
94/// impl<const SIZE: usize> Deref for IoMem<SIZE> {
95/// type Target = Io<SIZE>;
96///
97/// fn deref(&self) -> &Self::Target {
98/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
99/// unsafe { Io::from_raw(&self.0) }
100/// }
101/// }
102///
103///# fn no_run() -> Result<(), Error> {
104/// // SAFETY: Invalid usage for example purposes.
105/// let iomem = unsafe { IoMem::<{ core::mem::size_of::<u32>() }>::new(0xBAAAAAAD)? };
106/// iomem.write32(0x42, 0x0);
107/// assert!(iomem.try_write32(0x42, 0x0).is_ok());
108/// assert!(iomem.try_write32(0x42, 0x4).is_err());
109/// # Ok(())
110/// # }
111/// ```
112#[repr(transparent)]
113pub struct Io<const SIZE: usize = 0>(IoRaw<SIZE>);
114
115macro_rules! define_read {
116 ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident -> $type_name:ty) => {
117 /// Read IO data from a given offset known at compile time.
118 ///
119 /// Bound checks are performed on compile time, hence if the offset is not known at compile
120 /// time, the build will fail.
121 $(#[$attr])*
122 #[inline]
123 pub fn $name(&self, offset: usize) -> $type_name {
124 let addr = self.io_addr_assert::<$type_name>(offset);
125
126 // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
127 unsafe { bindings::$c_fn(addr as *const c_void) }
128 }
129
130 /// Read IO data from a given offset.
131 ///
132 /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
133 /// out of bounds.
134 $(#[$attr])*
135 pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
136 let addr = self.io_addr::<$type_name>(offset)?;
137
138 // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
139 Ok(unsafe { bindings::$c_fn(addr as *const c_void) })
140 }
141 };
142}
143
144macro_rules! define_write {
145 ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident <- $type_name:ty) => {
146 /// Write IO data from a given offset known at compile time.
147 ///
148 /// Bound checks are performed on compile time, hence if the offset is not known at compile
149 /// time, the build will fail.
150 $(#[$attr])*
151 #[inline]
152 pub fn $name(&self, value: $type_name, offset: usize) {
153 let addr = self.io_addr_assert::<$type_name>(offset);
154
155 // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
156 unsafe { bindings::$c_fn(value, addr as *mut c_void) }
157 }
158
159 /// Write IO data from a given offset.
160 ///
161 /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
162 /// out of bounds.
163 $(#[$attr])*
164 pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
165 let addr = self.io_addr::<$type_name>(offset)?;
166
167 // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
168 unsafe { bindings::$c_fn(value, addr as *mut c_void) }
169 Ok(())
170 }
171 };
172}
173
174impl<const SIZE: usize> Io<SIZE> {
175 /// Converts an `IoRaw` into an `Io` instance, providing the accessors to the MMIO mapping.
176 ///
177 /// # Safety
178 ///
179 /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size
180 /// `maxsize`.
181 pub unsafe fn from_raw(raw: &IoRaw<SIZE>) -> &Self {
182 // SAFETY: `Io` is a transparent wrapper around `IoRaw`.
183 unsafe { &*core::ptr::from_ref(raw).cast() }
184 }
185
186 /// Returns the base address of this mapping.
187 #[inline]
188 pub fn addr(&self) -> usize {
189 self.0.addr()
190 }
191
192 /// Returns the maximum size of this mapping.
193 #[inline]
194 pub fn maxsize(&self) -> usize {
195 self.0.maxsize()
196 }
197
198 #[inline]
199 const fn offset_valid<U>(offset: usize, size: usize) -> bool {
200 let type_size = core::mem::size_of::<U>();
201 if let Some(end) = offset.checked_add(type_size) {
202 end <= size && offset % type_size == 0
203 } else {
204 false
205 }
206 }
207
208 #[inline]
209 fn io_addr<U>(&self, offset: usize) -> Result<usize> {
210 if !Self::offset_valid::<U>(offset, self.maxsize()) {
211 return Err(EINVAL);
212 }
213
214 // Probably no need to check, since the safety requirements of `Self::new` guarantee that
215 // this can't overflow.
216 self.addr().checked_add(offset).ok_or(EINVAL)
217 }
218
219 #[inline]
220 fn io_addr_assert<U>(&self, offset: usize) -> usize {
221 build_assert!(Self::offset_valid::<U>(offset, SIZE));
222
223 self.addr() + offset
224 }
225
226 define_read!(read8, try_read8, readb -> u8);
227 define_read!(read16, try_read16, readw -> u16);
228 define_read!(read32, try_read32, readl -> u32);
229 define_read!(
230 #[cfg(CONFIG_64BIT)]
231 read64,
232 try_read64,
233 readq -> u64
234 );
235
236 define_read!(read8_relaxed, try_read8_relaxed, readb_relaxed -> u8);
237 define_read!(read16_relaxed, try_read16_relaxed, readw_relaxed -> u16);
238 define_read!(read32_relaxed, try_read32_relaxed, readl_relaxed -> u32);
239 define_read!(
240 #[cfg(CONFIG_64BIT)]
241 read64_relaxed,
242 try_read64_relaxed,
243 readq_relaxed -> u64
244 );
245
246 define_write!(write8, try_write8, writeb <- u8);
247 define_write!(write16, try_write16, writew <- u16);
248 define_write!(write32, try_write32, writel <- u32);
249 define_write!(
250 #[cfg(CONFIG_64BIT)]
251 write64,
252 try_write64,
253 writeq <- u64
254 );
255
256 define_write!(write8_relaxed, try_write8_relaxed, writeb_relaxed <- u8);
257 define_write!(write16_relaxed, try_write16_relaxed, writew_relaxed <- u16);
258 define_write!(write32_relaxed, try_write32_relaxed, writel_relaxed <- u32);
259 define_write!(
260 #[cfg(CONFIG_64BIT)]
261 write64_relaxed,
262 try_write64_relaxed,
263 writeq_relaxed <- u64
264 );
265}