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, ffi::c_void}; 9 10 pub mod mem; 11 pub mod resource; 12 13 pub 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. 23 pub struct IoRaw<const SIZE: usize = 0> { 24 addr: usize, 25 maxsize: usize, 26 } 27 28 impl<const SIZE: usize> IoRaw<SIZE> { 29 /// Returns a new `IoRaw` instance on success, an error otherwise. new(addr: usize, maxsize: usize) -> Result<Self>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] addr(&self) -> usize40 pub fn addr(&self) -> usize { 41 self.addr 42 } 43 44 /// Returns the maximum size of the MMIO region. 45 #[inline] maxsize(&self) -> usize46 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)] 113 pub struct Io<const SIZE: usize = 0>(IoRaw<SIZE>); 114 115 macro_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 } 143 144 macro_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 } 173 174 impl<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`. from_raw(raw: &IoRaw<SIZE>) -> &Self181 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] addr(&self) -> usize188 pub fn addr(&self) -> usize { 189 self.0.addr() 190 } 191 192 /// Returns the maximum size of this mapping. 193 #[inline] maxsize(&self) -> usize194 pub fn maxsize(&self) -> usize { 195 self.0.maxsize() 196 } 197 198 #[inline] offset_valid<U>(offset: usize, size: usize) -> bool199 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] io_addr<U>(&self, offset: usize) -> Result<usize>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] io_addr_assert<U>(&self, offset: usize) -> usize220 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 } 266