From: Alexandre Courbot Date: Sat, 14 Mar 2026 01:06:17 +0000 (+0900) Subject: rust: io: add `register!` macro X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=20ba6a1dbcb957152f6d858015b3a3311dd6da49;p=thirdparty%2Fkernel%2Flinux.git rust: io: add `register!` macro Add a macro for defining hardware register types with I/O accessors. Each register field is represented as a `Bounded` of the appropriate bit width, ensuring field values are never silently truncated. Fields can optionally be converted to/from custom types, either fallibly or infallibly. The address of registers can be direct, relative, or indexed, supporting most of the patterns in which registers are arranged. Suggested-by: Danilo Krummrich Link: https://lore.kernel.org/all/20250306222336.23482-6-dakr@kernel.org/ Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Alexandre Courbot Link: https://patch.msgid.link/20260314-register-v9-7-86805b2f7e9d@nvidia.com [ * Improve wording and formatting of doc-comments, * Import build_assert!(), * Add missing inline annotations, * Call static_assert!() with absolute path, * Use expect instead of allow. - Danilo ] Signed-off-by: Danilo Krummrich --- diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs index c51a87b9169b..4950cecf30ca 100644 --- a/rust/kernel/io.rs +++ b/rust/kernel/io.rs @@ -11,8 +11,10 @@ use crate::{ pub mod mem; pub mod poll; +pub mod register; pub mod resource; +pub use crate::register; pub use resource::Resource; /// Physical address type. @@ -179,7 +181,8 @@ pub trait IoCapable { /// 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. +/// (for primitive types like [`u32`]) and typed ones (like those generated by the [`register!`] +/// macro). /// /// An `IoLoc` carries three pieces of information: /// diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs new file mode 100644 index 000000000000..dbd458aaa761 --- /dev/null +++ b/rust/kernel/io/register.rs @@ -0,0 +1,1229 @@ +// 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((), new_boot0); +//! +//! // Or, build a new value from zero and write it: +//! io.write((), 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::() +//! .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 + From; + + /// 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 IoLoc 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 IoLoc 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(PhantomData); + +impl FixedRegisterLoc { + /// 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 IoLoc for FixedRegisterLoc +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 { + /// 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>() -> RelativeRegisterLoc + 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(PhantomData, PhantomData); + +impl RelativeRegisterLoc +where + T: Register + WithBase, + B: RegisterBase + ?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 IoLoc for RelativeRegisterLoc +where + T: RelativeRegister, + B: RegisterBase + ?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(usize, PhantomData); + +impl RegisterArrayLoc { + /// 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 { + if idx < T::SIZE { + Some(Self(idx, PhantomData)) + } else { + None + } + } +} + +impl IoLoc for RegisterArrayLoc +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 + 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> + 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 + ?Sized, +>(RelativeRegisterLoc, usize); + +impl RelativeRegisterArrayLoc +where + T: RelativeRegisterArray, + B: RegisterBase + ?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 { + if idx < T::SIZE { + Some(Self(RelativeRegisterLoc::new(), idx)) + } else { + None + } + } +} + +/// Methods exclusive to [`RelativeRegisterLoc`]s created with a [`RelativeRegisterArray`]. +impl RelativeRegisterLoc +where + T: RelativeRegisterArray, + B: RegisterBase + ?Sized, +{ + /// Returns the location of the register at position `idx`, with build-time validation. + #[inline(always)] + pub fn at(self, idx: usize) -> RelativeRegisterArrayLoc { + 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::try_new(idx) + } +} + +impl IoLoc for RelativeRegisterArrayLoc +where + T: RelativeRegisterArray, + B: RegisterBase + ?Sized, +{ + type IoType = T::Storage; + + #[inline(always)] + fn offset(self) -> usize { + self.0.offset() + self.1 * T::STRIDE + } +} + +/// 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); +/// # } +/// +/// ``` +/// +/// 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`. +/// +/// 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 for Cpu0 { +/// const BASE: usize = 0x100; +/// } +/// +/// // ZST describing `CPU1`. +/// struct Cpu1; +/// impl RegisterBase for Cpu1 { +/// const BASE: usize = 0x200; +/// } +/// +/// // This makes `CPU_CTL` accessible from all implementors of `RegisterBase`. +/// 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::()); +/// +/// // Stop `Cpu0`. +/// io.write(WithBase::of::(), 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::(), |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 for Cpu0 { +/// const BASE: usize = 0x100; +/// } +/// +/// // ZST describing `CPU1`. +/// struct Cpu1; +/// impl RegisterBase 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::().at(0)); +/// +/// // Write the retrieved value into scratch register 15 of CPU1. +/// io.write(WithBase::of::().at(15), scratch); +/// +/// // This won't build. +/// // let cpu0_scratch_128 = io.read(CPU_SCRATCH::of::().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::().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::()).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 = $lo..=$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::() + } + + 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 [](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 [](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 [](self) -> Self { + self.[<__with_ $field>]( + ::kernel::num::Bounded::<$storage, { $hi + 1 - $lo }>::new::() + ) + } + + $(#[doc = $doc])* + #[doc = "Sets this field to the given `value`."] + #[inline(always)] + $vis fn []( + self, + value: T, + ) -> Self + where T: Into<::kernel::num::Bounded<$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)] + $vis fn []( + self, + value: T, + ) -> ::kernel::error::Result + where T: ::kernel::num::TryIntoBounded<$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("", &::kernel::prelude::fmt!("{:#x}", self.inner)) + $( + .field(stringify!($field), &self.$field()) + )* + .finish() + } + } + }; +}