rust/kernel/io.rs - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 //! Memory-mapped IO.
 //!
 //! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)

 use crate::error::{code::EINVAL, Result};
 use crate::{bindings, build_assert, ffi::c_void};

 pub mod mem;
 pub mod resource;

 pub use resource::Resource;

 /// 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 `Io`
 /// instance providing the actual memory accessors. Only by the conversion into an `Io` structure
 /// any guarantees are given.
 pub struct IoRaw<const SIZE: usize = 0> {
     addr: usize,
     maxsize: usize,
 }

 impl<const SIZE: usize> IoRaw<SIZE> {
     /// Returns a new `IoRaw` 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, IoRaw}};
 /// # use core::ops::Deref;
 ///
 /// // See also [`pci::Bar`] for a real example.
 /// struct IoMem<const SIZE: usize>(IoRaw<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 bindings::phys_addr_t, SIZE) };
 ///         if addr.is_null() {
 ///             return Err(ENOMEM);
 ///         }
 ///
 ///         Ok(IoMem(IoRaw::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 = Io<SIZE>;
 ///
 ///    fn deref(&self) -> &Self::Target {
 ///         // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
 ///         unsafe { Io::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 Io<const SIZE: usize = 0>(IoRaw<SIZE>);

 macro_rules! define_read {
     ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident -> $type_name:ty) => {
         /// Read IO data from a given offset known at compile time.
         ///
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
         #[inline]
         pub fn $name(&self, offset: usize) -> $type_name {
             let addr = self.io_addr_assert::<$type_name>(offset);

             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             unsafe { bindings::$c_fn(addr as *const c_void) }
         }

         /// Read IO data from a given offset.
         ///
         /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
         /// out of bounds.
         $(#[$attr])*
         pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
             let addr = self.io_addr::<$type_name>(offset)?;

             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             Ok(unsafe { bindings::$c_fn(addr as *const c_void) })
         }
     };
 }

 macro_rules! define_write {
     ($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident <- $type_name:ty) => {
         /// Write IO data from a given offset known at compile time.
         ///
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
         #[inline]
         pub fn $name(&self, value: $type_name, offset: usize) {
             let addr = self.io_addr_assert::<$type_name>(offset);

             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             unsafe { bindings::$c_fn(value, addr as *mut c_void) }
         }

         /// Write IO data from a given offset.
         ///
         /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
         /// out of bounds.
         $(#[$attr])*
         pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
             let addr = self.io_addr::<$type_name>(offset)?;

             // SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
             unsafe { bindings::$c_fn(value, addr as *mut c_void) }
             Ok(())
         }
     };
 }

 impl<const SIZE: usize> Io<SIZE> {
     /// Converts an `IoRaw` into an `Io` 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: &IoRaw<SIZE>) -> &Self {
         // SAFETY: `Io` is a transparent wrapper around `IoRaw`.
         unsafe { &*core::ptr::from_ref(raw).cast() }
     }

     /// Returns the base address of this mapping.
     #[inline]
     pub fn addr(&self) -> usize {
         self.0.addr()
     }

     /// Returns the maximum size of this mapping.
     #[inline]
     pub fn maxsize(&self) -> usize {
         self.0.maxsize()
     }

     #[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
         }
     }

     #[inline]
     fn io_addr<U>(&self, offset: usize) -> Result<usize> {
         if !Self::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)
     }

     #[inline]
     fn io_addr_assert<U>(&self, offset: usize) -> usize {
         build_assert!(Self::offset_valid::<U>(offset, SIZE));

         self.addr() + offset
     }

     define_read!(read8, try_read8, readb -> u8);
     define_read!(read16, try_read16, readw -> u16);
     define_read!(read32, try_read32, readl -> u32);
     define_read!(
         #[cfg(CONFIG_64BIT)]
         read64,
         try_read64,
         readq -> u64
     );

     define_read!(read8_relaxed, try_read8_relaxed, readb_relaxed -> u8);
     define_read!(read16_relaxed, try_read16_relaxed, readw_relaxed -> u16);
     define_read!(read32_relaxed, try_read32_relaxed, readl_relaxed -> u32);
     define_read!(
         #[cfg(CONFIG_64BIT)]
         read64_relaxed,
         try_read64_relaxed,
         readq_relaxed -> u64
     );

     define_write!(write8, try_write8, writeb <- u8);
     define_write!(write16, try_write16, writew <- u16);
     define_write!(write32, try_write32, writel <- u32);
     define_write!(
         #[cfg(CONFIG_64BIT)]
         write64,
         try_write64,
         writeq <- u64
     );

     define_write!(write8_relaxed, try_write8_relaxed, writeb_relaxed <- u8);
     define_write!(write16_relaxed, try_write16_relaxed, writew_relaxed <- u16);
     define_write!(write32_relaxed, try_write32_relaxed, writel_relaxed <- u32);
     define_write!(
         #[cfg(CONFIG_64BIT)]
         write64_relaxed,
         try_write64_relaxed,
         writeq_relaxed <- u64
     );
 }
	// SPDX-License-Identifier: GPL-2.0

	//! Memory-mapped IO.
	//!
	//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)

	use crate::error::{code::EINVAL, Result};
	use crate::{bindings, build_assert, ffi::c_void};

	pub mod mem;
	pub mod resource;

	pub use resource::Resource;

	/// 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 `Io`
	/// instance providing the actual memory accessors. Only by the conversion into an `Io` structure
	/// any guarantees are given.
	pub struct IoRaw<const SIZE: usize = 0> {
	addr: usize,
	maxsize: usize,
	}

	impl<const SIZE: usize> IoRaw<SIZE> {
	/// Returns a new `IoRaw` 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, IoRaw}};
	/// # use core::ops::Deref;
	///
	/// // See also [`pci::Bar`] for a real example.
	/// struct IoMem<const SIZE: usize>(IoRaw<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 bindings::phys_addr_t, SIZE) };
	/// if addr.is_null() {
	/// return Err(ENOMEM);
	/// }
	///
	/// Ok(IoMem(IoRaw::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 = Io<SIZE>;
	///
	/// fn deref(&self) -> &Self::Target {
	/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
	/// unsafe { Io::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 Io<const SIZE: usize = 0>(IoRaw<SIZE>);

	macro_rules! define_read {
	($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident -> $type_name:ty) => {
	/// Read IO data from a given offset known at compile time.
	///
	/// Bound checks are performed on compile time, hence if the offset is not known at compile
	/// time, the build will fail.
	$(#[$attr])*
	#[inline]
	pub fn $name(&self, offset: usize) -> $type_name {
	let addr = self.io_addr_assert::<$type_name>(offset);

	// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
	unsafe { bindings::$c_fn(addr as *const c_void) }
	}

	/// Read IO data from a given offset.
	///
	/// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
	/// out of bounds.
	$(#[$attr])*
	pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
	let addr = self.io_addr::<$type_name>(offset)?;

	// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
	Ok(unsafe { bindings::$c_fn(addr as *const c_void) })
	}
	};
	}

	macro_rules! define_write {
	($(#[$attr:meta])* $name:ident, $try_name:ident, $c_fn:ident <- $type_name:ty) => {
	/// Write IO data from a given offset known at compile time.
	///
	/// Bound checks are performed on compile time, hence if the offset is not known at compile
	/// time, the build will fail.
	$(#[$attr])*
	#[inline]
	pub fn $name(&self, value: $type_name, offset: usize) {
	let addr = self.io_addr_assert::<$type_name>(offset);

	// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
	unsafe { bindings::$c_fn(value, addr as *mut c_void) }
	}

	/// Write IO data from a given offset.
	///
	/// Bound checks are performed on runtime, it fails if the offset (plus the type size) is
	/// out of bounds.
	$(#[$attr])*
	pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
	let addr = self.io_addr::<$type_name>(offset)?;

	// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
	unsafe { bindings::$c_fn(value, addr as *mut c_void) }
	Ok(())
	}
	};
	}

	impl<const SIZE: usize> Io<SIZE> {
	/// Converts an `IoRaw` into an `Io` 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: &IoRaw<SIZE>) -> &Self {
	// SAFETY: `Io` is a transparent wrapper around `IoRaw`.
	unsafe { &*core::ptr::from_ref(raw).cast() }
	}

	/// Returns the base address of this mapping.
	#[inline]
	pub fn addr(&self) -> usize {
	self.0.addr()
	}

	/// Returns the maximum size of this mapping.
	#[inline]
	pub fn maxsize(&self) -> usize {
	self.0.maxsize()
	}

	#[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
	}
	}

	#[inline]
	fn io_addr<U>(&self, offset: usize) -> Result<usize> {
	if !Self::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)
	}

	#[inline]
	fn io_addr_assert<U>(&self, offset: usize) -> usize {
	build_assert!(Self::offset_valid::<U>(offset, SIZE));

	self.addr() + offset
	}

	define_read!(read8, try_read8, readb -> u8);
	define_read!(read16, try_read16, readw -> u16);
	define_read!(read32, try_read32, readl -> u32);
	define_read!(
	#[cfg(CONFIG_64BIT)]
	read64,
	try_read64,
	readq -> u64
	);

	define_read!(read8_relaxed, try_read8_relaxed, readb_relaxed -> u8);
	define_read!(read16_relaxed, try_read16_relaxed, readw_relaxed -> u16);
	define_read!(read32_relaxed, try_read32_relaxed, readl_relaxed -> u32);
	define_read!(
	#[cfg(CONFIG_64BIT)]
	read64_relaxed,
	try_read64_relaxed,
	readq_relaxed -> u64
	);

	define_write!(write8, try_write8, writeb <- u8);
	define_write!(write16, try_write16, writew <- u16);
	define_write!(write32, try_write32, writel <- u32);
	define_write!(
	#[cfg(CONFIG_64BIT)]
	write64,
	try_write64,
	writeq <- u64
	);

	define_write!(write8_relaxed, try_write8_relaxed, writeb_relaxed <- u8);
	define_write!(write16_relaxed, try_write16_relaxed, writew_relaxed <- u16);
	define_write!(write32_relaxed, try_write32_relaxed, writel_relaxed <- u32);
	define_write!(
	#[cfg(CONFIG_64BIT)]
	write64_relaxed,
	try_write64_relaxed,
	writeq_relaxed <- u64
	);
	}