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zircon-guest/third_party/linux/refs/heads/master/./rust/kernel/io/register.rs
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// SPDX-License-Identifier: GPL-2.0
//! Macro to define register layout and accessors.
//!
//! The [`register!`](kernel::io::register!) macro provides an intuitive and readable syntax for
//! defining a dedicated type for each register and accessing it using [`Io`](super::Io). Each such
//! type comes with its own field accessors that can return an error if a field's value is invalid.
//!
//! Note: most of the items in this module are public so they can be referenced by the macro, but
//! most are not to be used directly by users. Outside of the `register!` macro itself, the only
//! items you might want to import from this module are [`WithBase`] and [`Array`].
//!
//! # Simple example
//!
//! ```no_run
//! use kernel::io::register;
//!
//! register! {
//! /// Basic information about the chip.
//! pub BOOT_0(u32) @ 0x00000100 {
//! /// Vendor ID.
//! 15:8 vendor_id;
//! /// Major revision of the chip.
//! 7:4 major_revision;
//! /// Minor revision of the chip.
//! 3:0 minor_revision;
//! }
//! }
//! ```
//!
//! This defines a 32-bit `BOOT_0` type which can be read from or written to offset `0x100` of an
//! `Io` region, with the described bitfields. For instance, `minor_revision` consists of the 4
//! least significant bits of the type.
//!
//! Fields are instances of [`Bounded`](kernel::num::Bounded) and can be read by calling their
//! getter method, which is named after them. They also have setter methods prefixed with `with_`
//! for runtime values and `with_const_` for constant values. All setters return the updated
//! register value.
//!
//! Fields can also be transparently converted from/to an arbitrary type by using the `=>` and
//! `?=>` syntaxes.
//!
//! If present, doc comments above register or fields definitions are added to the relevant item
//! they document (the register type itself, or the field's setter and getter methods).
//!
//! Note that multiple registers can be defined in a single `register!` invocation. This can be
//! useful to group related registers together.
//!
//! Here is how the register defined above can be used in code:
//!
//!
//! ```no_run
//! use kernel::{
//! io::{
//! register,
//! Io,
//! IoLoc,
//! },
//! num::Bounded,
//! };
//! # use kernel::io::Mmio;
//! # register! {
//! # pub BOOT_0(u32) @ 0x00000100 {
//! # 15:8 vendor_id;
//! # 7:4 major_revision;
//! # 3:0 minor_revision;
//! # }
//! # }
//! # fn test(io: &Mmio<0x1000>) {
//! # fn obtain_vendor_id() -> u8 { 0xff }
//!
//! // Read from the register's defined offset (0x100).
//! let boot0 = io.read(BOOT_0);
//! pr_info!("chip revision: {}.{}", boot0.major_revision().get(), boot0.minor_revision().get());
//!
//! // Update some fields and write the new value back.
//! let new_boot0 = boot0
//! // Constant values.
//! .with_const_major_revision::<3>()
//! .with_const_minor_revision::<10>()
//! // Runtime value.
//! .with_vendor_id(obtain_vendor_id());
//! io.write_reg(new_boot0);
//!
//! // Or, build a new value from zero and write it:
//! io.write_reg(BOOT_0::zeroed()
//! .with_const_major_revision::<3>()
//! .with_const_minor_revision::<10>()
//! .with_vendor_id(obtain_vendor_id())
//! );
//!
//! // Or, read and update the register in a single step.
//! io.update(BOOT_0, |r| r
//! .with_const_major_revision::<3>()
//! .with_const_minor_revision::<10>()
//! .with_vendor_id(obtain_vendor_id())
//! );
//!
//! // Constant values can also be built using the const setters.
//! const V: BOOT_0 = pin_init::zeroed::<BOOT_0>()
//! .with_const_major_revision::<3>()
//! .with_const_minor_revision::<10>();
//! # }
//! ```
//!
//! For more extensive documentation about how to define registers, see the
//! [`register!`](kernel::io::register!) macro.
use core::marker::PhantomData;
use crate::io::IoLoc;
use kernel::build_assert;
/// Trait implemented by all registers.
pub trait Register: Sized {
/// Backing primitive type of the register.
type Storage: Into<Self> + From<Self>;
/// Start offset of the register.
///
/// The interpretation of this offset depends on the type of the register.
const OFFSET: usize;
}
/// Trait implemented by registers with a fixed offset.
pub trait FixedRegister: Register {}
/// Allows `()` to be used as the `location` parameter of [`Io::write`](super::Io::write) when
/// passing a [`FixedRegister`] value.
impl<T> IoLoc<T> for ()
where
T: FixedRegister,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
T::OFFSET
}
}
/// A [`FixedRegister`] carries its location in its type. Thus `FixedRegister` values can be used
/// as an [`IoLoc`].
impl<T> IoLoc<T> for T
where
T: FixedRegister,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
T::OFFSET
}
}
/// Location of a fixed register.
pub struct FixedRegisterLoc<T: FixedRegister>(PhantomData<T>);
impl<T: FixedRegister> FixedRegisterLoc<T> {
/// Returns the location of `T`.
#[inline(always)]
// We do not implement `Default` so we can be const.
#[expect(clippy::new_without_default)]
pub const fn new() -> Self {
Self(PhantomData)
}
}
impl<T> IoLoc<T> for FixedRegisterLoc<T>
where
T: FixedRegister,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
T::OFFSET
}
}
/// Trait providing a base address to be added to the offset of a relative register to obtain
/// its actual offset.
///
/// The `T` generic argument is used to distinguish which base to use, in case a type provides
/// several bases. It is given to the `register!` macro to restrict the use of the register to
/// implementors of this particular variant.
pub trait RegisterBase<T> {
/// Base address to which register offsets are added.
const BASE: usize;
}
/// Trait implemented by all registers that are relative to a base.
pub trait WithBase {
/// Family of bases applicable to this register.
type BaseFamily;
/// Returns the absolute location of this type when using `B` as its base.
#[inline(always)]
fn of<B: RegisterBase<Self::BaseFamily>>() -> RelativeRegisterLoc<Self, B>
where
Self: Register,
{
RelativeRegisterLoc::new()
}
}
/// Trait implemented by relative registers.
pub trait RelativeRegister: Register + WithBase {}
/// Location of a relative register.
///
/// This can either be an immediately accessible regular [`RelativeRegister`], or a
/// [`RelativeRegisterArray`] that needs one additional resolution through
/// [`RelativeRegisterLoc::at`].
pub struct RelativeRegisterLoc<T: WithBase, B: ?Sized>(PhantomData<T>, PhantomData<B>);
impl<T, B> RelativeRegisterLoc<T, B>
where
T: Register + WithBase,
B: RegisterBase<T::BaseFamily> + ?Sized,
{
/// Returns the location of a relative register or register array.
#[inline(always)]
// We do not implement `Default` so we can be const.
#[expect(clippy::new_without_default)]
pub const fn new() -> Self {
Self(PhantomData, PhantomData)
}
// Returns the absolute offset of the relative register using base `B`.
//
// This is implemented as a private const method so it can be reused by the [`IoLoc`]
// implementations of both [`RelativeRegisterLoc`] and [`RelativeRegisterArrayLoc`].
#[inline]
const fn offset(self) -> usize {
B::BASE + T::OFFSET
}
}
impl<T, B> IoLoc<T> for RelativeRegisterLoc<T, B>
where
T: RelativeRegister,
B: RegisterBase<T::BaseFamily> + ?Sized,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
RelativeRegisterLoc::offset(self)
}
}
/// Trait implemented by arrays of registers.
pub trait RegisterArray: Register {
/// Number of elements in the registers array.
const SIZE: usize;
/// Number of bytes between the start of elements in the registers array.
const STRIDE: usize;
}
/// Location of an array register.
pub struct RegisterArrayLoc<T: RegisterArray>(usize, PhantomData<T>);
impl<T: RegisterArray> RegisterArrayLoc<T> {
/// Returns the location of register `T` at position `idx`, with build-time validation.
#[inline(always)]
pub fn new(idx: usize) -> Self {
build_assert!(idx < T::SIZE);
Self(idx, PhantomData)
}
/// Attempts to return the location of register `T` at position `idx`, with runtime validation.
#[inline(always)]
pub fn try_new(idx: usize) -> Option<Self> {
if idx < T::SIZE {
Some(Self(idx, PhantomData))
} else {
None
}
}
}
impl<T> IoLoc<T> for RegisterArrayLoc<T>
where
T: RegisterArray,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
T::OFFSET + self.0 * T::STRIDE
}
}
/// Trait providing location builders for [`RegisterArray`]s.
pub trait Array {
/// Returns the location of the register at position `idx`, with build-time validation.
#[inline(always)]
fn at(idx: usize) -> RegisterArrayLoc<Self>
where
Self: RegisterArray,
{
RegisterArrayLoc::new(idx)
}
/// Returns the location of the register at position `idx`, with runtime validation.
#[inline(always)]
fn try_at(idx: usize) -> Option<RegisterArrayLoc<Self>>
where
Self: RegisterArray,
{
RegisterArrayLoc::try_new(idx)
}
}
/// Trait implemented by arrays of relative registers.
pub trait RelativeRegisterArray: RegisterArray + WithBase {}
/// Location of a relative array register.
pub struct RelativeRegisterArrayLoc<
T: RelativeRegisterArray,
B: RegisterBase<T::BaseFamily> + ?Sized,
>(RelativeRegisterLoc<T, B>, usize);
impl<T, B> RelativeRegisterArrayLoc<T, B>
where
T: RelativeRegisterArray,
B: RegisterBase<T::BaseFamily> + ?Sized,
{
/// Returns the location of register `T` from the base `B` at index `idx`, with build-time
/// validation.
#[inline(always)]
pub fn new(idx: usize) -> Self {
build_assert!(idx < T::SIZE);
Self(RelativeRegisterLoc::new(), idx)
}
/// Attempts to return the location of register `T` from the base `B` at index `idx`, with
/// runtime validation.
#[inline(always)]
pub fn try_new(idx: usize) -> Option<Self> {
if idx < T::SIZE {
Some(Self(RelativeRegisterLoc::new(), idx))
} else {
None
}
}
}
/// Methods exclusive to [`RelativeRegisterLoc`]s created with a [`RelativeRegisterArray`].
impl<T, B> RelativeRegisterLoc<T, B>
where
T: RelativeRegisterArray,
B: RegisterBase<T::BaseFamily> + ?Sized,
{
/// Returns the location of the register at position `idx`, with build-time validation.
#[inline(always)]
pub fn at(self, idx: usize) -> RelativeRegisterArrayLoc<T, B> {
RelativeRegisterArrayLoc::new(idx)
}
/// Returns the location of the register at position `idx`, with runtime validation.
#[inline(always)]
pub fn try_at(self, idx: usize) -> Option<RelativeRegisterArrayLoc<T, B>> {
RelativeRegisterArrayLoc::try_new(idx)
}
}
impl<T, B> IoLoc<T> for RelativeRegisterArrayLoc<T, B>
where
T: RelativeRegisterArray,
B: RegisterBase<T::BaseFamily> + ?Sized,
{
type IoType = T::Storage;
#[inline(always)]
fn offset(self) -> usize {
self.0.offset() + self.1 * T::STRIDE
}
}
/// Trait implemented by items that contain both a register value and the absolute I/O location at
/// which to write it.
///
/// Implementors can be used with [`Io::write_reg`](super::Io::write_reg).
pub trait LocatedRegister {
/// Register value to write.
type Value: Register;
/// Full location information at which to write the value.
type Location: IoLoc<Self::Value>;
/// Consumes `self` and returns a `(location, value)` tuple describing a valid I/O write
/// operation.
fn into_io_op(self) -> (Self::Location, Self::Value);
}
impl<T> LocatedRegister for T
where
T: FixedRegister,
{
type Location = FixedRegisterLoc<Self::Value>;
type Value = T;
#[inline(always)]
fn into_io_op(self) -> (FixedRegisterLoc<T>, T) {
(FixedRegisterLoc::new(), self)
}
}
/// Defines a dedicated type for a register, including getter and setter methods for its fields and
/// methods to read and write it from an [`Io`](kernel::io::Io) region.
///
/// This documentation focuses on how to declare registers. See the [module-level
/// documentation](mod@kernel::io::register) for examples of how to access them.
///
/// There are 4 possible kinds of registers: fixed offset registers, relative registers, arrays of
/// registers, and relative arrays of registers.
///
/// ## Fixed offset registers
///
/// These are the simplest kind of registers. Their location is simply an offset inside the I/O
/// region. For instance:
///
/// ```ignore
/// register! {
/// pub FIXED_REG(u16) @ 0x80 {
/// ...
/// }
/// }
/// ```
///
/// This creates a 16-bit register named `FIXED_REG` located at offset `0x80` of an I/O region.
///
/// These registers' location can be built simply by referencing their name:
///
/// ```no_run
/// use kernel::{
/// io::{
/// register,
/// Io,
/// },
/// };
/// # use kernel::io::Mmio;
///
/// register! {
/// FIXED_REG(u32) @ 0x100 {
/// 16:8 high_byte;
/// 7:0 low_byte;
/// }
/// }
///
/// # fn test(io: &Mmio<0x1000>) {
/// let val = io.read(FIXED_REG);
///
/// // Write from an already-existing value.
/// io.write(FIXED_REG, val.with_low_byte(0xff));
///
/// // Create a register value from scratch.
/// let val2 = FIXED_REG::zeroed().with_high_byte(0x80);
///
/// // The location of fixed offset registers is already contained in their type. Thus, the
/// // `location` argument of `Io::write` is technically redundant and can be replaced by `()`.
/// io.write((), val2);
///
/// // Or, the single-argument `Io::write_reg` can be used.
/// io.write_reg(val2);
/// # }
///
/// ```
///
/// It is possible to create an alias of an existing register with new field definitions by using
/// the `=> ALIAS` syntax. This is useful for cases where a register's interpretation depends on
/// the context:
///
/// ```no_run
/// use kernel::io::register;
///
/// register! {
/// /// Scratch register.
/// pub SCRATCH(u32) @ 0x00000200 {
/// 31:0 value;
/// }
///
/// /// Boot status of the firmware.
/// pub SCRATCH_BOOT_STATUS(u32) => SCRATCH {
/// 0:0 completed;
/// }
/// }
/// ```
///
/// In this example, `SCRATCH_BOOT_STATUS` uses the same I/O address as `SCRATCH`, while providing
/// its own `completed` field.
///
/// ## Relative registers
///
/// Relative registers can be instantiated several times at a relative offset of a group of bases.
/// For instance, imagine the following I/O space:
///
/// ```text
/// +-----------------------------+
/// | ... |
/// | |
/// 0x100--->+------------CPU0-------------+
/// | |
/// 0x110--->+-----------------------------+
/// | CPU_CTL |
/// +-----------------------------+
/// | ... |
/// | |
/// | |
/// 0x200--->+------------CPU1-------------+
/// | |
/// 0x210--->+-----------------------------+
/// | CPU_CTL |
/// +-----------------------------+
/// | ... |
/// +-----------------------------+
/// ```
///
/// `CPU0` and `CPU1` both have a `CPU_CTL` register that starts at offset `0x10` of their I/O
/// space segment. Since both instances of `CPU_CTL` share the same layout, we don't want to define
/// them twice and would prefer a way to select which one to use from a single definition.
///
/// This can be done using the `Base + Offset` syntax when specifying the register's address:
///
/// ```ignore
/// register! {
/// pub RELATIVE_REG(u32) @ Base + 0x80 {
/// ...
/// }
/// }
/// ```
///
/// This creates a register with an offset of `0x80` from a given base.
///
/// `Base` is an arbitrary type (typically a ZST) to be used as a generic parameter of the
/// [`RegisterBase`] trait to provide the base as a constant, i.e. each type providing a base for
/// this register needs to implement `RegisterBase<Base>`.
///
/// The location of relative registers can be built using the [`WithBase::of`] method to specify
/// its base. All relative registers implement [`WithBase`].
///
/// Here is the above layout translated into code:
///
/// ```no_run
/// use kernel::{
/// io::{
/// register,
/// register::{
/// RegisterBase,
/// WithBase,
/// },
/// Io,
/// },
/// };
/// # use kernel::io::Mmio;
///
/// // Type used to identify the base.
/// pub struct CpuCtlBase;
///
/// // ZST describing `CPU0`.
/// struct Cpu0;
/// impl RegisterBase<CpuCtlBase> for Cpu0 {
/// const BASE: usize = 0x100;
/// }
///
/// // ZST describing `CPU1`.
/// struct Cpu1;
/// impl RegisterBase<CpuCtlBase> for Cpu1 {
/// const BASE: usize = 0x200;
/// }
///
/// // This makes `CPU_CTL` accessible from all implementors of `RegisterBase<CpuCtlBase>`.
/// register! {
/// /// CPU core control.
/// pub CPU_CTL(u32) @ CpuCtlBase + 0x10 {
/// 0:0 start;
/// }
/// }
///
/// # fn test(io: Mmio<0x1000>) {
/// // Read the status of `Cpu0`.
/// let cpu0_started = io.read(CPU_CTL::of::<Cpu0>());
///
/// // Stop `Cpu0`.
/// io.write(WithBase::of::<Cpu0>(), CPU_CTL::zeroed());
/// # }
///
/// // Aliases can also be defined for relative register.
/// register! {
/// /// Alias to CPU core control.
/// pub CPU_CTL_ALIAS(u32) => CpuCtlBase + CPU_CTL {
/// /// Start the aliased CPU core.
/// 1:1 alias_start;
/// }
/// }
///
/// # fn test2(io: Mmio<0x1000>) {
/// // Start the aliased `CPU0`, leaving its other fields untouched.
/// io.update(CPU_CTL_ALIAS::of::<Cpu0>(), |r| r.with_alias_start(true));
/// # }
/// ```
///
/// ## Arrays of registers
///
/// Some I/O areas contain consecutive registers that share the same field layout. These areas can
/// be defined as an array of identical registers, allowing them to be accessed by index with
/// compile-time or runtime bound checking:
///
/// ```ignore
/// register! {
/// pub REGISTER_ARRAY(u8)[10, stride = 4] @ 0x100 {
/// ...
/// }
/// }
/// ```
///
/// This defines `REGISTER_ARRAY`, an array of 10 byte registers starting at offset `0x100`. Each
/// register is separated from its neighbor by 4 bytes.
///
/// The `stride` parameter is optional; if unspecified, the registers are placed consecutively from
/// each other.
///
/// A location for a register in a register array is built using the [`Array::at`] trait method.
/// All arrays of registers implement [`Array`].
///
/// ```no_run
/// use kernel::{
/// io::{
/// register,
/// register::Array,
/// Io,
/// },
/// };
/// # use kernel::io::Mmio;
/// # fn get_scratch_idx() -> usize {
/// # 0x15
/// # }
///
/// // Array of 64 consecutive registers with the same layout starting at offset `0x80`.
/// register! {
/// /// Scratch registers.
/// pub SCRATCH(u32)[64] @ 0x00000080 {
/// 31:0 value;
/// }
/// }
///
/// # fn test(io: &Mmio<0x1000>)
/// # -> Result<(), Error>{
/// // Read scratch register 0, i.e. I/O address `0x80`.
/// let scratch_0 = io.read(SCRATCH::at(0)).value();
///
/// // Write scratch register 15, i.e. I/O address `0x80 + (15 * 4)`.
/// io.write(Array::at(15), SCRATCH::from(0xffeeaabb));
///
/// // This is out of bounds and won't build.
/// // let scratch_128 = io.read(SCRATCH::at(128)).value();
///
/// // Runtime-obtained array index.
/// let idx = get_scratch_idx();
/// // Access on a runtime index returns an error if it is out-of-bounds.
/// let some_scratch = io.read(SCRATCH::try_at(idx).ok_or(EINVAL)?).value();
///
/// // Alias to a specific register in an array.
/// // Here `SCRATCH[8]` is used to convey the firmware exit code.
/// register! {
/// /// Firmware exit status code.
/// pub FIRMWARE_STATUS(u32) => SCRATCH[8] {
/// 7:0 status;
/// }
/// }
///
/// let status = io.read(FIRMWARE_STATUS).status();
///
/// // Non-contiguous register arrays can be defined by adding a stride parameter.
/// // Here, each of the 16 registers of the array is separated by 8 bytes, meaning that the
/// // registers of the two declarations below are interleaved.
/// register! {
/// /// Scratch registers bank 0.
/// pub SCRATCH_INTERLEAVED_0(u32)[16, stride = 8] @ 0x000000c0 {
/// 31:0 value;
/// }
///
/// /// Scratch registers bank 1.
/// pub SCRATCH_INTERLEAVED_1(u32)[16, stride = 8] @ 0x000000c4 {
/// 31:0 value;
/// }
/// }
/// # Ok(())
/// # }
/// ```
///
/// ## Relative arrays of registers
///
/// Combining the two features described in the sections above, arrays of registers accessible from
/// a base can also be defined:
///
/// ```ignore
/// register! {
/// pub RELATIVE_REGISTER_ARRAY(u8)[10, stride = 4] @ Base + 0x100 {
/// ...
/// }
/// }
/// ```
///
/// Like relative registers, they implement the [`WithBase`] trait. However the return value of
/// [`WithBase::of`] cannot be used directly as a location and must be further specified using the
/// [`at`](RelativeRegisterLoc::at) method.
///
/// ```no_run
/// use kernel::{
/// io::{
/// register,
/// register::{
/// RegisterBase,
/// WithBase,
/// },
/// Io,
/// },
/// };
/// # use kernel::io::Mmio;
/// # fn get_scratch_idx() -> usize {
/// # 0x15
/// # }
///
/// // Type used as parameter of `RegisterBase` to specify the base.
/// pub struct CpuCtlBase;
///
/// // ZST describing `CPU0`.
/// struct Cpu0;
/// impl RegisterBase<CpuCtlBase> for Cpu0 {
/// const BASE: usize = 0x100;
/// }
///
/// // ZST describing `CPU1`.
/// struct Cpu1;
/// impl RegisterBase<CpuCtlBase> for Cpu1 {
/// const BASE: usize = 0x200;
/// }
///
/// // 64 per-cpu scratch registers, arranged as a contiguous array.
/// register! {
/// /// Per-CPU scratch registers.
/// pub CPU_SCRATCH(u32)[64] @ CpuCtlBase + 0x00000080 {
/// 31:0 value;
/// }
/// }
///
/// # fn test(io: &Mmio<0x1000>) -> Result<(), Error> {
/// // Read scratch register 0 of CPU0.
/// let scratch = io.read(CPU_SCRATCH::of::<Cpu0>().at(0));
///
/// // Write the retrieved value into scratch register 15 of CPU1.
/// io.write(WithBase::of::<Cpu1>().at(15), scratch);
///
/// // This won't build.
/// // let cpu0_scratch_128 = io.read(CPU_SCRATCH::of::<Cpu0>().at(128)).value();
///
/// // Runtime-obtained array index.
/// let scratch_idx = get_scratch_idx();
/// // Access on a runtime index returns an error if it is out-of-bounds.
/// let cpu0_scratch = io.read(
/// CPU_SCRATCH::of::<Cpu0>().try_at(scratch_idx).ok_or(EINVAL)?
/// ).value();
/// # Ok(())
/// # }
///
/// // Alias to `SCRATCH[8]` used to convey the firmware exit code.
/// register! {
/// /// Per-CPU firmware exit status code.
/// pub CPU_FIRMWARE_STATUS(u32) => CpuCtlBase + CPU_SCRATCH[8] {
/// 7:0 status;
/// }
/// }
///
/// // Non-contiguous relative register arrays can be defined by adding a stride parameter.
/// // Here, each of the 16 registers of the array is separated by 8 bytes, meaning that the
/// // registers of the two declarations below are interleaved.
/// register! {
/// /// Scratch registers bank 0.
/// pub CPU_SCRATCH_INTERLEAVED_0(u32)[16, stride = 8] @ CpuCtlBase + 0x00000d00 {
/// 31:0 value;
/// }
///
/// /// Scratch registers bank 1.
/// pub CPU_SCRATCH_INTERLEAVED_1(u32)[16, stride = 8] @ CpuCtlBase + 0x00000d04 {
/// 31:0 value;
/// }
/// }
///
/// # fn test2(io: &Mmio<0x1000>) -> Result<(), Error> {
/// let cpu0_status = io.read(CPU_FIRMWARE_STATUS::of::<Cpu0>()).status();
/// # Ok(())
/// # }
/// ```
#[macro_export]
macro_rules! register {
// Entry point for the macro, allowing multiple registers to be defined in one call.
// It matches all possible register declaration patterns to dispatch them to corresponding
// `@reg` rule that defines a single register.
(
$(
$(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
$([ $size:expr $(, stride = $stride:expr)? ])?
$(@ $($base:ident +)? $offset:literal)?
$(=> $alias:ident $(+ $alias_offset:ident)? $([$alias_idx:expr])? )?
{ $($fields:tt)* }
)*
) => {
$(
$crate::register!(
@reg $(#[$attr])* $vis $name ($storage) $([$size $(, stride = $stride)?])?
$(@ $($base +)? $offset)?
$(=> $alias $(+ $alias_offset)? $([$alias_idx])? )?
{ $($fields)* }
);
)*
};
// All the rules below are private helpers.
// Creates a register at a fixed offset of the MMIO space.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) @ $offset:literal
{ $($fields:tt)* }
) => {
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(@io_base $name($storage) @ $offset);
$crate::register!(@io_fixed $(#[$attr])* $vis $name($storage));
};
// Creates an alias register of fixed offset register `alias` with its own fields.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) => $alias:ident
{ $($fields:tt)* }
) => {
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(
@io_base $name($storage) @
<$alias as $crate::io::register::Register>::OFFSET
);
$crate::register!(@io_fixed $(#[$attr])* $vis $name($storage));
};
// Creates a register at a relative offset from a base address provider.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) @ $base:ident + $offset:literal
{ $($fields:tt)* }
) => {
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(@io_base $name($storage) @ $offset);
$crate::register!(@io_relative $vis $name($storage) @ $base);
};
// Creates an alias register of relative offset register `alias` with its own fields.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) => $base:ident + $alias:ident
{ $($fields:tt)* }
) => {
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(
@io_base $name($storage) @ <$alias as $crate::io::register::Register>::OFFSET
);
$crate::register!(@io_relative $vis $name($storage) @ $base);
};
// Creates an array of registers at a fixed offset of the MMIO space.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
[ $size:expr, stride = $stride:expr ] @ $offset:literal { $($fields:tt)* }
) => {
::kernel::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(@io_base $name($storage) @ $offset);
$crate::register!(@io_array $vis $name($storage) [ $size, stride = $stride ]);
};
// Shortcut for contiguous array of registers (stride == size of element).
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) [ $size:expr ] @ $offset:literal
{ $($fields:tt)* }
) => {
$crate::register!(
$(#[$attr])* $vis $name($storage) [ $size, stride = ::core::mem::size_of::<$storage>() ]
@ $offset { $($fields)* }
);
};
// Creates an alias of register `idx` of array of registers `alias` with its own fields.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) => $alias:ident [ $idx:expr ]
{ $($fields:tt)* }
) => {
::kernel::static_assert!($idx < <$alias as $crate::io::register::RegisterArray>::SIZE);
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(
@io_base $name($storage) @
<$alias as $crate::io::register::Register>::OFFSET
+ $idx * <$alias as $crate::io::register::RegisterArray>::STRIDE
);
$crate::register!(@io_fixed $(#[$attr])* $vis $name($storage));
};
// Creates an array of registers at a relative offset from a base address provider.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
[ $size:expr, stride = $stride:expr ]
@ $base:ident + $offset:literal { $($fields:tt)* }
) => {
::kernel::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(@io_base $name($storage) @ $offset);
$crate::register!(
@io_relative_array $vis $name($storage) [ $size, stride = $stride ] @ $base + $offset
);
};
// Shortcut for contiguous array of relative registers (stride == size of element).
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) [ $size:expr ]
@ $base:ident + $offset:literal { $($fields:tt)* }
) => {
$crate::register!(
$(#[$attr])* $vis $name($storage) [ $size, stride = ::core::mem::size_of::<$storage>() ]
@ $base + $offset { $($fields)* }
);
};
// Creates an alias of register `idx` of relative array of registers `alias` with its own
// fields.
(
@reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
=> $base:ident + $alias:ident [ $idx:expr ] { $($fields:tt)* }
) => {
::kernel::static_assert!($idx < <$alias as $crate::io::register::RegisterArray>::SIZE);
$crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
$crate::register!(
@io_base $name($storage) @
<$alias as $crate::io::register::Register>::OFFSET +
$idx * <$alias as $crate::io::register::RegisterArray>::STRIDE
);
$crate::register!(@io_relative $vis $name($storage) @ $base);
};
// Generates the bitfield for the register.
//
// `#[allow(non_camel_case_types)]` is added since register names typically use
// `SCREAMING_CASE`.
(
@bitfield $(#[$attr:meta])* $vis:vis struct $name:ident($storage:ty) { $($fields:tt)* }
) => {
$crate::register!(@bitfield_core
#[allow(non_camel_case_types)]
$(#[$attr])* $vis $name $storage
);
$crate::register!(@bitfield_fields $vis $name $storage { $($fields)* });
};
// Implementations shared by all registers types.
(@io_base $name:ident($storage:ty) @ $offset:expr) => {
impl $crate::io::register::Register for $name {
type Storage = $storage;
const OFFSET: usize = $offset;
}
};
// Implementations of fixed registers.
(@io_fixed $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)) => {
impl $crate::io::register::FixedRegister for $name {}
$(#[$attr])*
$vis const $name: $crate::io::register::FixedRegisterLoc<$name> =
$crate::io::register::FixedRegisterLoc::<$name>::new();
};
// Implementations of relative registers.
(@io_relative $vis:vis $name:ident ($storage:ty) @ $base:ident) => {
impl $crate::io::register::WithBase for $name {
type BaseFamily = $base;
}
impl $crate::io::register::RelativeRegister for $name {}
};
// Implementations of register arrays.
(@io_array $vis:vis $name:ident ($storage:ty) [ $size:expr, stride = $stride:expr ]) => {
impl $crate::io::register::Array for $name {}
impl $crate::io::register::RegisterArray for $name {
const SIZE: usize = $size;
const STRIDE: usize = $stride;
}
};
// Implementations of relative array registers.
(
@io_relative_array $vis:vis $name:ident ($storage:ty) [ $size:expr, stride = $stride:expr ]
@ $base:ident + $offset:literal
) => {
impl $crate::io::register::WithBase for $name {
type BaseFamily = $base;
}
impl $crate::io::register::RegisterArray for $name {
const SIZE: usize = $size;
const STRIDE: usize = $stride;
}
impl $crate::io::register::RelativeRegisterArray for $name {}
};
// Defines the wrapper `$name` type and its conversions from/to the storage type.
(@bitfield_core $(#[$attr:meta])* $vis:vis $name:ident $storage:ty) => {
$(#[$attr])*
#[repr(transparent)]
#[derive(Clone, Copy, PartialEq, Eq)]
$vis struct $name {
inner: $storage,
}
#[allow(dead_code)]
impl $name {
/// Creates a bitfield from a raw value.
#[inline(always)]
$vis const fn from_raw(value: $storage) -> Self {
Self{ inner: value }
}
/// Turns this bitfield into its raw value.
///
/// This is similar to the [`From`] implementation, but is shorter to invoke in
/// most cases.
#[inline(always)]
$vis const fn into_raw(self) -> $storage {
self.inner
}
}
// SAFETY: `$storage` is `Zeroable` and `$name` is transparent.
unsafe impl ::pin_init::Zeroable for $name {}
impl ::core::convert::From<$name> for $storage {
#[inline(always)]
fn from(val: $name) -> $storage {
val.into_raw()
}
}
impl ::core::convert::From<$storage> for $name {
#[inline(always)]
fn from(val: $storage) -> $name {
Self::from_raw(val)
}
}
};
// Definitions requiring knowledge of individual fields: private and public field accessors,
// and `Debug` implementation.
(@bitfield_fields $vis:vis $name:ident $storage:ty {
$($(#[doc = $doc:expr])* $hi:literal:$lo:literal $field:ident
$(?=> $try_into_type:ty)?
$(=> $into_type:ty)?
;
)*
}
) => {
#[allow(dead_code)]
impl $name {
$(
$crate::register!(@private_field_accessors $vis $name $storage : $hi:$lo $field);
$crate::register!(
@public_field_accessors $(#[doc = $doc])* $vis $name $storage : $hi:$lo $field
$(?=> $try_into_type)?
$(=> $into_type)?
);
)*
}
$crate::register!(@debug $name { $($field;)* });
};
// Private field accessors working with the exact `Bounded` type for the field.
(
@private_field_accessors $vis:vis $name:ident $storage:ty : $hi:tt:$lo:tt $field:ident
) => {
::kernel::macros::paste!(
$vis const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi;
$vis const [<$field:upper _MASK>]: $storage =
((((1 << $hi) - 1) << 1) + 1) - ((1 << $lo) - 1);
$vis const [<$field:upper _SHIFT>]: u32 = $lo;
);
::kernel::macros::paste!(
fn [<__ $field>](self) ->
::kernel::num::Bounded<$storage, { $hi + 1 - $lo }> {
// Left shift to align the field's MSB with the storage MSB.
const ALIGN_TOP: u32 = $storage::BITS - ($hi + 1);
// Right shift to move the top-aligned field to bit 0 of the storage.
const ALIGN_BOTTOM: u32 = ALIGN_TOP + $lo;
// Extract the field using two shifts. `Bounded::shr` produces the correctly-sized
// output type.
let val = ::kernel::num::Bounded::<$storage, { $storage::BITS }>::from(
self.inner << ALIGN_TOP
);
val.shr::<ALIGN_BOTTOM, { $hi + 1 - $lo } >()
}
const fn [<__with_ $field>](
mut self,
value: ::kernel::num::Bounded<$storage, { $hi + 1 - $lo }>,
) -> Self
{
const MASK: $storage = <$name>::[<$field:upper _MASK>];
const SHIFT: u32 = <$name>::[<$field:upper _SHIFT>];
let value = value.get() << SHIFT;
self.inner = (self.inner & !MASK) | value;
self
}
);
};
// Public accessors for fields infallibly (`=>`) converted to a type.
(
@public_field_accessors $(#[doc = $doc:expr])* $vis:vis $name:ident $storage:ty :
$hi:literal:$lo:literal $field:ident => $into_type:ty
) => {
::kernel::macros::paste!(
$(#[doc = $doc])*
#[doc = "Returns the value of this field."]
#[inline(always)]
$vis fn $field(self) -> $into_type
{
self.[<__ $field>]().into()
}
$(#[doc = $doc])*
#[doc = "Sets this field to the given `value`."]
#[inline(always)]
$vis fn [<with_ $field>](self, value: $into_type) -> Self
{
self.[<__with_ $field>](value.into())
}
);
};
// Public accessors for fields fallibly (`?=>`) converted to a type.
(
@public_field_accessors $(#[doc = $doc:expr])* $vis:vis $name:ident $storage:ty :
$hi:tt:$lo:tt $field:ident ?=> $try_into_type:ty
) => {
::kernel::macros::paste!(
$(#[doc = $doc])*
#[doc = "Returns the value of this field."]
#[inline(always)]
$vis fn $field(self) ->
Result<
$try_into_type,
<$try_into_type as ::core::convert::TryFrom<
::kernel::num::Bounded<$storage, { $hi + 1 - $lo }>
>>::Error
>
{
self.[<__ $field>]().try_into()
}
$(#[doc = $doc])*
#[doc = "Sets this field to the given `value`."]
#[inline(always)]
$vis fn [<with_ $field>](self, value: $try_into_type) -> Self
{
self.[<__with_ $field>](value.into())
}
);
};
// Public accessors for fields not converted to a type.
(
@public_field_accessors $(#[doc = $doc:expr])* $vis:vis $name:ident $storage:ty :
$hi:tt:$lo:tt $field:ident
) => {
::kernel::macros::paste!(
$(#[doc = $doc])*
#[doc = "Returns the value of this field."]
#[inline(always)]
$vis fn $field(self) ->
::kernel::num::Bounded<$storage, { $hi + 1 - $lo }>
{
self.[<__ $field>]()
}
$(#[doc = $doc])*
#[doc = "Sets this field to the compile-time constant `VALUE`."]
#[inline(always)]
$vis const fn [<with_const_ $field>]<const VALUE: $storage>(self) -> Self {
self.[<__with_ $field>](
::kernel::num::Bounded::<$storage, { $hi + 1 - $lo }>::new::<VALUE>()
)
}
$(#[doc = $doc])*
#[doc = "Sets this field to the given `value`."]
#[inline(always)]
$vis fn [<with_ $field>]<T>(
self,
value: T,
) -> Self
where T: Into<::kernel::num::Bounded<$storage, { $hi + 1 - $lo }>>,
{
self.[<__with_ $field>](value.into())
}
$(#[doc = $doc])*
#[doc = "Tries to set this field to `value`, returning an error if it is out of range."]
#[inline(always)]
$vis fn [<try_with_ $field>]<T>(
self,
value: T,
) -> ::kernel::error::Result<Self>
where T: ::kernel::num::TryIntoBounded<$storage, { $hi + 1 - $lo }>,
{
Ok(
self.[<__with_ $field>](
value.try_into_bounded().ok_or(::kernel::error::code::EOVERFLOW)?
)
)
}
);
};
// `Debug` implementation.
(@debug $name:ident { $($field:ident;)* }) => {
impl ::kernel::fmt::Debug for $name {
fn fmt(&self, f: &mut ::kernel::fmt::Formatter<'_>) -> ::kernel::fmt::Result {
f.debug_struct(stringify!($name))
.field("<raw>", &::kernel::prelude::fmt!("{:#x}", self.inner))
$(
.field(stringify!($field), &self.$field())
)*
.finish()
}
}
};
}