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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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//! Memory-mapped IO.//!//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)
use crate::{ bindings, prelude::*, //};
pub mod mem;pub mod poll;pub mod register;pub mod resource;
pub use crate::register;pub use resource::Resource;
use register::LocatedRegister;
/// Physical address type.////// This is a type alias to either `u32` or `u64` depending on the config option/// `CONFIG_PHYS_ADDR_T_64BIT`, and it can be a u64 even on 32-bit architectures.pub type PhysAddr = bindings::phys_addr_t;
/// Resource Size type.////// This is a type alias to either `u32` or `u64` depending on the config option/// `CONFIG_PHYS_ADDR_T_64BIT`, and it can be a u64 even on 32-bit architectures.pub type ResourceSize = bindings::resource_size_t;
/// Raw representation of an MMIO region.////// By itself, the existence of an instance of this structure does not provide any guarantees that/// the represented MMIO region does exist or is properly mapped.////// Instead, the bus specific MMIO implementation must convert this raw representation into an/// `Mmio` instance providing the actual memory accessors. Only by the conversion into an `Mmio`/// structure any guarantees are given.pub struct MmioRaw<const SIZE: usize = 0> { addr: usize, maxsize: usize,}
impl<const SIZE: usize> MmioRaw<SIZE> { /// Returns a new `MmioRaw` instance on success, an error otherwise. pub fn new(addr: usize, maxsize: usize) -> Result<Self> { if maxsize < SIZE { return Err(EINVAL); }
Ok(Self { addr, maxsize }) }
/// Returns the base address of the MMIO region. #[inline] pub fn addr(&self) -> usize { self.addr }
/// Returns the maximum size of the MMIO region. #[inline] pub fn maxsize(&self) -> usize { self.maxsize }}
/// IO-mapped memory region.////// The creator (usually a subsystem / bus such as PCI) is responsible for creating the/// mapping, performing an additional region request etc.////// # Invariant////// `addr` is the start and `maxsize` the length of valid I/O mapped memory region of size/// `maxsize`.////// # Examples////// ```no_run/// use kernel::{/// bindings,/// ffi::c_void,/// io::{/// Io,/// IoKnownSize,/// Mmio,/// MmioRaw,/// PhysAddr,/// },/// };/// use core::ops::Deref;////// // See also `pci::Bar` for a real example./// struct IoMem<const SIZE: usize>(MmioRaw<SIZE>);////// impl<const SIZE: usize> IoMem<SIZE> {/// /// # Safety/// ////// /// [`paddr`, `paddr` + `SIZE`) must be a valid MMIO region that is mappable into the CPUs/// /// virtual address space./// unsafe fn new(paddr: usize) -> Result<Self>{/// // SAFETY: By the safety requirements of this function [`paddr`, `paddr` + `SIZE`) is/// // valid for `ioremap`./// let addr = unsafe { bindings::ioremap(paddr as PhysAddr, SIZE) };/// if addr.is_null() {/// return Err(ENOMEM);/// }////// Ok(IoMem(MmioRaw::new(addr as usize, SIZE)?))/// }/// }////// impl<const SIZE: usize> Drop for IoMem<SIZE> {/// fn drop(&mut self) {/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`./// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };/// }/// }////// impl<const SIZE: usize> Deref for IoMem<SIZE> {/// type Target = Mmio<SIZE>;////// fn deref(&self) -> &Self::Target {/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`./// unsafe { Mmio::from_raw(&self.0) }/// }/// }//////# fn no_run() -> Result<(), Error> {/// // SAFETY: Invalid usage for example purposes./// let iomem = unsafe { IoMem::<{ core::mem::size_of::<u32>() }>::new(0xBAAAAAAD)? };/// iomem.write32(0x42, 0x0);/// assert!(iomem.try_write32(0x42, 0x0).is_ok());/// assert!(iomem.try_write32(0x42, 0x4).is_err());/// # Ok(())/// # }/// ```#[repr(transparent)]pub struct Mmio<const SIZE: usize = 0>(MmioRaw<SIZE>);
/// Checks whether an access of type `U` at the given `offset`/// is valid within this region.#[inline]const fn offset_valid<U>(offset: usize, size: usize) -> bool { let type_size = core::mem::size_of::<U>(); if let Some(end) = offset.checked_add(type_size) { end <= size && offset % type_size == 0 } else { false }}
/// Trait indicating that an I/O backend supports operations of a certain type and providing an/// implementation for these operations.////// Different I/O backends can implement this trait to expose only the operations they support.////// For example, a PCI configuration space may implement `IoCapable<u8>`, `IoCapable<u16>`,/// and `IoCapable<u32>`, but not `IoCapable<u64>`, while an MMIO region on a 64-bit/// system might implement all four.pub trait IoCapable<T> { /// Performs an I/O read of type `T` at `address` and returns the result. /// /// # Safety /// /// The range `[address..address + size_of::<T>()]` must be within the bounds of `Self`. unsafe fn io_read(&self, address: usize) -> T;
/// Performs an I/O write of `value` at `address`. /// /// # Safety /// /// The range `[address..address + size_of::<T>()]` must be within the bounds of `Self`. unsafe fn io_write(&self, value: T, address: usize);}
/// Describes a given I/O location: its offset, width, and type to convert the raw value from and/// into.////// This trait is the key abstraction allowing [`Io::read`], [`Io::write`], and [`Io::update`] (and/// their fallible [`try_read`](Io::try_read), [`try_write`](Io::try_write) and/// [`try_update`](Io::try_update) counterparts) to work uniformly with both raw [`usize`] offsets/// (for primitive types like [`u32`]) and typed ones (like those generated by the [`register!`]/// macro).////// An `IoLoc<T>` carries three pieces of information:////// - The offset to access (returned by [`IoLoc::offset`]),/// - The width of the access (determined by [`IoLoc::IoType`]),/// - The type `T` in which the raw data is returned or provided.////// `T` and `IoLoc::IoType` may differ: for instance, a typed register has `T` = the register type/// with its bitfields, and `IoType` = its backing primitive (e.g. `u32`).pub trait IoLoc<T> { /// Size ([`u8`], [`u16`], etc) of the I/O performed on the returned [`offset`](IoLoc::offset). type IoType: Into<T> + From<T>;
/// Consumes `self` and returns the offset of this location. fn offset(self) -> usize;}
/// Implements [`IoLoc<$ty>`] for [`usize`], allowing [`usize`] to be used as a parameter of/// [`Io::read`] and [`Io::write`].macro_rules! impl_usize_ioloc { ($($ty:ty),*) => { $( impl IoLoc<$ty> for usize { type IoType = $ty;
#[inline(always)] fn offset(self) -> usize { self } } )* }}
// Provide the ability to read any primitive type from a [`usize`].impl_usize_ioloc!(u8, u16, u32, u64);
/// Types implementing this trait (e.g. MMIO BARs or PCI config regions)/// can perform I/O operations on regions of memory.////// This is an abstract representation to be implemented by arbitrary I/O/// backends (e.g. MMIO, PCI config space, etc.).////// The [`Io`] trait provides:/// - Base address and size information/// - Helper methods for offset validation and address calculation/// - Fallible (runtime checked) accessors for different data widths////// Which I/O methods are available depends on which [`IoCapable<T>`] traits/// are implemented for the type.////// # Examples////// For MMIO regions, all widths (u8, u16, u32, and u64 on 64-bit systems) are typically/// supported. For PCI configuration space, u8, u16, and u32 are supported but u64 is not.pub trait Io { /// Returns the base address of this mapping. fn addr(&self) -> usize;
/// Returns the maximum size of this mapping. fn maxsize(&self) -> usize;
/// Returns the absolute I/O address for a given `offset`, /// performing runtime bound checks. #[inline] fn io_addr<U>(&self, offset: usize) -> Result<usize> { if !offset_valid::<U>(offset, self.maxsize()) { return Err(EINVAL); }
// Probably no need to check, since the safety requirements of `Self::new` guarantee that // this can't overflow. self.addr().checked_add(offset).ok_or(EINVAL) }
/// Fallible 8-bit read with runtime bounds check. #[inline(always)] fn try_read8(&self, offset: usize) -> Result<u8> where Self: IoCapable<u8>, { self.try_read(offset) }
/// Fallible 16-bit read with runtime bounds check. #[inline(always)] fn try_read16(&self, offset: usize) -> Result<u16> where Self: IoCapable<u16>, { self.try_read(offset) }
/// Fallible 32-bit read with runtime bounds check. #[inline(always)] fn try_read32(&self, offset: usize) -> Result<u32> where Self: IoCapable<u32>, { self.try_read(offset) }
/// Fallible 64-bit read with runtime bounds check. #[inline(always)] fn try_read64(&self, offset: usize) -> Result<u64> where Self: IoCapable<u64>, { self.try_read(offset) }
/// Fallible 8-bit write with runtime bounds check. #[inline(always)] fn try_write8(&self, value: u8, offset: usize) -> Result where Self: IoCapable<u8>, { self.try_write(offset, value) }
/// Fallible 16-bit write with runtime bounds check. #[inline(always)] fn try_write16(&self, value: u16, offset: usize) -> Result where Self: IoCapable<u16>, { self.try_write(offset, value) }
/// Fallible 32-bit write with runtime bounds check. #[inline(always)] fn try_write32(&self, value: u32, offset: usize) -> Result where Self: IoCapable<u32>, { self.try_write(offset, value) }
/// Fallible 64-bit write with runtime bounds check. #[inline(always)] fn try_write64(&self, value: u64, offset: usize) -> Result where Self: IoCapable<u64>, { self.try_write(offset, value) }
/// Infallible 8-bit read with compile-time bounds check. #[inline(always)] fn read8(&self, offset: usize) -> u8 where Self: IoKnownSize + IoCapable<u8>, { self.read(offset) }
/// Infallible 16-bit read with compile-time bounds check. #[inline(always)] fn read16(&self, offset: usize) -> u16 where Self: IoKnownSize + IoCapable<u16>, { self.read(offset) }
/// Infallible 32-bit read with compile-time bounds check. #[inline(always)] fn read32(&self, offset: usize) -> u32 where Self: IoKnownSize + IoCapable<u32>, { self.read(offset) }
/// Infallible 64-bit read with compile-time bounds check. #[inline(always)] fn read64(&self, offset: usize) -> u64 where Self: IoKnownSize + IoCapable<u64>, { self.read(offset) }
/// Infallible 8-bit write with compile-time bounds check. #[inline(always)] fn write8(&self, value: u8, offset: usize) where Self: IoKnownSize + IoCapable<u8>, { self.write(offset, value) }
/// Infallible 16-bit write with compile-time bounds check. #[inline(always)] fn write16(&self, value: u16, offset: usize) where Self: IoKnownSize + IoCapable<u16>, { self.write(offset, value) }
/// Infallible 32-bit write with compile-time bounds check. #[inline(always)] fn write32(&self, value: u32, offset: usize) where Self: IoKnownSize + IoCapable<u32>, { self.write(offset, value) }
/// Infallible 64-bit write with compile-time bounds check. #[inline(always)] fn write64(&self, value: u64, offset: usize) where Self: IoKnownSize + IoCapable<u64>, { self.write(offset, value) }
/// Generic fallible read with runtime bounds check. /// /// # Examples /// /// Read a primitive type from an I/O address: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_reads(io: &Mmio) -> Result { /// // 32-bit read from address `0x10`. /// let v: u32 = io.try_read(0x10)?; /// /// // 8-bit read from address `0xfff`. /// let v: u8 = io.try_read(0xfff)?; /// /// Ok(()) /// } /// ``` #[inline(always)] fn try_read<T, L>(&self, location: L) -> Result<T> where L: IoLoc<T>, Self: IoCapable<L::IoType>, { let address = self.io_addr::<L::IoType>(location.offset())?;
// SAFETY: `address` has been validated by `io_addr`. Ok(unsafe { self.io_read(address) }.into()) }
/// Generic fallible write with runtime bounds check. /// /// # Examples /// /// Write a primitive type to an I/O address: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_writes(io: &Mmio) -> Result { /// // 32-bit write of value `1` at address `0x10`. /// io.try_write(0x10, 1u32)?; /// /// // 8-bit write of value `0xff` at address `0xfff`. /// io.try_write(0xfff, 0xffu8)?; /// /// Ok(()) /// } /// ``` #[inline(always)] fn try_write<T, L>(&self, location: L, value: T) -> Result where L: IoLoc<T>, Self: IoCapable<L::IoType>, { let address = self.io_addr::<L::IoType>(location.offset())?; let io_value = value.into();
// SAFETY: `address` has been validated by `io_addr`. unsafe { self.io_write(io_value, address) }
Ok(()) }
/// Generic fallible write of a fully-located register value. /// /// # Examples /// /// Tuples carrying a location and a value can be used with this method: /// /// ```no_run /// use kernel::io::{ /// register, /// Io, /// Mmio, /// }; /// /// register! { /// VERSION(u32) @ 0x100 { /// 15:8 major; /// 7:0 minor; /// } /// } /// /// impl VERSION { /// fn new(major: u8, minor: u8) -> Self { /// VERSION::zeroed().with_major(major).with_minor(minor) /// } /// } /// /// fn do_write_reg(io: &Mmio) -> Result { /// /// io.try_write_reg(VERSION::new(1, 0)) /// } /// ``` #[inline(always)] fn try_write_reg<T, L, V>(&self, value: V) -> Result where L: IoLoc<T>, V: LocatedRegister<Location = L, Value = T>, Self: IoCapable<L::IoType>, { let (location, value) = value.into_io_op();
self.try_write(location, value) }
/// Generic fallible update with runtime bounds check. /// /// Note: this does not perform any synchronization. The caller is responsible for ensuring /// exclusive access if required. /// /// # Examples /// /// Read the u32 value at address `0x10`, increment it, and store the updated value back: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_update(io: &Mmio<0x1000>) -> Result { /// io.try_update(0x10, |v: u32| { /// v + 1 /// }) /// } /// ``` #[inline(always)] fn try_update<T, L, F>(&self, location: L, f: F) -> Result where L: IoLoc<T>, Self: IoCapable<L::IoType>, F: FnOnce(T) -> T, { let address = self.io_addr::<L::IoType>(location.offset())?;
// SAFETY: `address` has been validated by `io_addr`. let value: T = unsafe { self.io_read(address) }.into(); let io_value = f(value).into();
// SAFETY: `address` has been validated by `io_addr`. unsafe { self.io_write(io_value, address) }
Ok(()) }
/// Generic infallible read with compile-time bounds check. /// /// # Examples /// /// Read a primitive type from an I/O address: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_reads(io: &Mmio<0x1000>) { /// // 32-bit read from address `0x10`. /// let v: u32 = io.read(0x10); /// /// // 8-bit read from the top of the I/O space. /// let v: u8 = io.read(0xfff); /// } /// ``` #[inline(always)] fn read<T, L>(&self, location: L) -> T where L: IoLoc<T>, Self: IoKnownSize + IoCapable<L::IoType>, { let address = self.io_addr_assert::<L::IoType>(location.offset());
// SAFETY: `address` has been validated by `io_addr_assert`. unsafe { self.io_read(address) }.into() }
/// Generic infallible write with compile-time bounds check. /// /// # Examples /// /// Write a primitive type to an I/O address: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_writes(io: &Mmio<0x1000>) { /// // 32-bit write of value `1` at address `0x10`. /// io.write(0x10, 1u32); /// /// // 8-bit write of value `0xff` at the top of the I/O space. /// io.write(0xfff, 0xffu8); /// } /// ``` #[inline(always)] fn write<T, L>(&self, location: L, value: T) where L: IoLoc<T>, Self: IoKnownSize + IoCapable<L::IoType>, { let address = self.io_addr_assert::<L::IoType>(location.offset()); let io_value = value.into();
// SAFETY: `address` has been validated by `io_addr_assert`. unsafe { self.io_write(io_value, address) } }
/// Generic infallible write of a fully-located register value. /// /// # Examples /// /// Tuples carrying a location and a value can be used with this method: /// /// ```no_run /// use kernel::io::{ /// register, /// Io, /// Mmio, /// }; /// /// register! { /// VERSION(u32) @ 0x100 { /// 15:8 major; /// 7:0 minor; /// } /// } /// /// impl VERSION { /// fn new(major: u8, minor: u8) -> Self { /// VERSION::zeroed().with_major(major).with_minor(minor) /// } /// } /// /// fn do_write_reg(io: &Mmio<0x1000>) { /// io.write_reg(VERSION::new(1, 0)); /// } /// ``` #[inline(always)] fn write_reg<T, L, V>(&self, value: V) where L: IoLoc<T>, V: LocatedRegister<Location = L, Value = T>, Self: IoKnownSize + IoCapable<L::IoType>, { let (location, value) = value.into_io_op();
self.write(location, value) }
/// Generic infallible update with compile-time bounds check. /// /// Note: this does not perform any synchronization. The caller is responsible for ensuring /// exclusive access if required. /// /// # Examples /// /// Read the u32 value at address `0x10`, increment it, and store the updated value back: /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// }; /// /// fn do_update(io: &Mmio<0x1000>) { /// io.update(0x10, |v: u32| { /// v + 1 /// }) /// } /// ``` #[inline(always)] fn update<T, L, F>(&self, location: L, f: F) where L: IoLoc<T>, Self: IoKnownSize + IoCapable<L::IoType> + Sized, F: FnOnce(T) -> T, { let address = self.io_addr_assert::<L::IoType>(location.offset());
// SAFETY: `address` has been validated by `io_addr_assert`. let value: T = unsafe { self.io_read(address) }.into(); let io_value = f(value).into();
// SAFETY: `address` has been validated by `io_addr_assert`. unsafe { self.io_write(io_value, address) } }}
/// Trait for types with a known size at compile time.////// This trait is implemented by I/O backends that have a compile-time known size,/// enabling the use of infallible I/O accessors with compile-time bounds checking.////// Types implementing this trait can use the infallible methods in [`Io`] trait/// (e.g., `read8`, `write32`), which require `Self: IoKnownSize` bound.pub trait IoKnownSize: Io { /// Minimum usable size of this region. const MIN_SIZE: usize;
/// Returns the absolute I/O address for a given `offset`, /// performing compile-time bound checks. // Always inline to optimize out error path of `build_assert`. #[inline(always)] fn io_addr_assert<U>(&self, offset: usize) -> usize { build_assert!(offset_valid::<U>(offset, Self::MIN_SIZE));
self.addr() + offset }}
/// Implements [`IoCapable`] on `$mmio` for `$ty` using `$read_fn` and `$write_fn`.macro_rules! impl_mmio_io_capable { ($mmio:ident, $(#[$attr:meta])* $ty:ty, $read_fn:ident, $write_fn:ident) => { $(#[$attr])* impl<const SIZE: usize> IoCapable<$ty> for $mmio<SIZE> { unsafe fn io_read(&self, address: usize) -> $ty { // SAFETY: By the trait invariant `address` is a valid address for MMIO operations. unsafe { bindings::$read_fn(address as *const c_void) } }
unsafe fn io_write(&self, value: $ty, address: usize) { // SAFETY: By the trait invariant `address` is a valid address for MMIO operations. unsafe { bindings::$write_fn(value, address as *mut c_void) } } } };}
// MMIO regions support 8, 16, and 32-bit accesses.impl_mmio_io_capable!(Mmio, u8, readb, writeb);impl_mmio_io_capable!(Mmio, u16, readw, writew);impl_mmio_io_capable!(Mmio, u32, readl, writel);// MMIO regions on 64-bit systems also support 64-bit accesses.impl_mmio_io_capable!( Mmio, #[cfg(CONFIG_64BIT)] u64, readq, writeq);
impl<const SIZE: usize> Io for Mmio<SIZE> { /// Returns the base address of this mapping. #[inline] fn addr(&self) -> usize { self.0.addr() }
/// Returns the maximum size of this mapping. #[inline] fn maxsize(&self) -> usize { self.0.maxsize() }}
impl<const SIZE: usize> IoKnownSize for Mmio<SIZE> { const MIN_SIZE: usize = SIZE;}
impl<const SIZE: usize> Mmio<SIZE> { /// Converts an `MmioRaw` into an `Mmio` instance, providing the accessors to the MMIO mapping. /// /// # Safety /// /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size /// `maxsize`. pub unsafe fn from_raw(raw: &MmioRaw<SIZE>) -> &Self { // SAFETY: `Mmio` is a transparent wrapper around `MmioRaw`. unsafe { &*core::ptr::from_ref(raw).cast() } }}
/// [`Mmio`] wrapper using relaxed accessors.////// This type provides an implementation of [`Io`] that uses relaxed I/O MMIO operands instead of/// the regular ones.////// See [`Mmio::relaxed`] for a usage example.#[repr(transparent)]pub struct RelaxedMmio<const SIZE: usize = 0>(Mmio<SIZE>);
impl<const SIZE: usize> Io for RelaxedMmio<SIZE> { #[inline] fn addr(&self) -> usize { self.0.addr() }
#[inline] fn maxsize(&self) -> usize { self.0.maxsize() }}
impl<const SIZE: usize> IoKnownSize for RelaxedMmio<SIZE> { const MIN_SIZE: usize = SIZE;}
impl<const SIZE: usize> Mmio<SIZE> { /// Returns a [`RelaxedMmio`] reference that performs relaxed I/O operations. /// /// Relaxed accessors do not provide ordering guarantees with respect to DMA or memory accesses /// and can be used when such ordering is not required. /// /// # Examples /// /// ```no_run /// use kernel::io::{ /// Io, /// Mmio, /// RelaxedMmio, /// }; /// /// fn do_io(io: &Mmio<0x100>) { /// // The access is performed using `readl_relaxed` instead of `readl`. /// let v = io.relaxed().read32(0x10); /// } /// /// ``` pub fn relaxed(&self) -> &RelaxedMmio<SIZE> { // SAFETY: `RelaxedMmio` is `#[repr(transparent)]` over `Mmio`, so `Mmio<SIZE>` and // `RelaxedMmio<SIZE>` have identical layout. unsafe { core::mem::transmute(self) } }}
// MMIO regions support 8, 16, and 32-bit accesses.impl_mmio_io_capable!(RelaxedMmio, u8, readb_relaxed, writeb_relaxed);impl_mmio_io_capable!(RelaxedMmio, u16, readw_relaxed, writew_relaxed);impl_mmio_io_capable!(RelaxedMmio, u32, readl_relaxed, writel_relaxed);// MMIO regions on 64-bit systems also support 64-bit accesses.impl_mmio_io_capable!( RelaxedMmio, #[cfg(CONFIG_64BIT)] u64, readq_relaxed, writeq_relaxed);