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+// SPDX-License-Identifier: GPL-2.0
+
+//! Macro to define register layout and accessors.
+//!
+//! A single register typically includes several fields, which are accessed through a combination
+//! of bit-shift and mask operations that introduce a class of potential mistakes, notably because
+//! not all possible field values are necessarily valid.
+//!
+//! The macro in this module allow to define, using an intruitive and readable syntax, a dedicated
+//! type for each register with its own field accessors that can return an error is a field's value
+//! is invalid.
+
+/// Defines a dedicated type for a register with an absolute offset, alongside with getter and
+/// setter methods for its fields and methods to read and write it from an `Io` region.
+///
+/// Example:
+///
+/// ```no_run
+/// register!(BOOT_0 @ 0x00000100, "Basic revision information about the GPU" {
+/// 3:0 minor_revision as u8, "Minor revision of the chip";
+/// 7:4 major_revision as u8, "Major revision of the chip";
+/// 28:20 chipset as u32 ?=> Chipset, "Chipset model";
+/// });
+/// ```
+///
+/// This defines a `BOOT_0` type which can be read or written from offset `0x100` of an `Io`
+/// region. It is composed of 3 fields, for instance `minor_revision` is made of the 4 less
+/// significant bits of the register. Each field can be accessed and modified using accessor
+/// methods:
+///
+/// ```no_run
+/// // Read from the register's defined offset (0x100).
+/// let boot0 = BOOT_0::read(&bar);
+/// pr_info!("chip revision: {}.{}", boot0.major_revision(), boot0.minor_revision());
+///
+/// // `Chipset::try_from` will be called with the value of the field and returns an error if the
+/// // value is invalid.
+/// let chipset = boot0.chipset()?;
+///
+/// // Update some fields and write the value back.
+/// boot0.set_major_revision(3).set_minor_revision(10).write(&bar);
+///
+/// // Or just read and update the register in a single step:
+/// BOOT_0::alter(&bar, |r| r.set_major_revision(3).set_minor_revision(10));
+/// ```
+///
+/// Fields can be defined as follows:
+///
+/// - `as <type>` simply returns the field value casted as the requested integer type, typically
+/// `u32`, `u16`, `u8` or `bool`. Note that `bool` fields must have a range of 1 bit.
+/// - `as <type> => <into_type>` calls `<into_type>`'s `From::<<type>>` implementation and returns
+/// the result.
+/// - `as <type> ?=> <try_into_type>` calls `<try_into_type>`'s `TryFrom::<<type>>` implementation
+/// and returns the result. This is useful on fields for which not all values are value.
+///
+/// The documentation strings are optional. If present, they will be added to the type's
+/// definition, or the field getter and setter methods they are attached to.
+///
+/// Putting a `+` before the address of the register makes it relative to a base: the `read` and
+/// `write` methods take a `base` argument that is added to the specified address before access,
+/// and `try_read` and `try_write` methods are also created, allowing access with offsets unknown
+/// at compile-time:
+///
+/// ```no_run
+/// register!(CPU_CTL @ +0x0000010, "CPU core control" {
+/// 0:0 start as bool, "Start the CPU core";
+/// });
+///
+/// // Flip the `start` switch for the CPU core which base address is at `CPU_BASE`.
+/// let cpuctl = CPU_CTL::read(&bar, CPU_BASE);
+/// pr_info!("CPU CTL: {:#x}", cpuctl);
+/// cpuctl.set_start(true).write(&bar, CPU_BASE);
+/// ```
+macro_rules! register {
+ // Creates a register at a fixed offset of the MMIO space.
+ (
+ $name:ident @ $offset:literal $(, $comment:literal)? {
+ $($fields:tt)*
+ }
+ ) => {
+ register!(@common $name $(, $comment)?);
+ register!(@field_accessors $name { $($fields)* });
+ register!(@io $name @ $offset);
+ };
+
+ // Creates a register at a relative offset from a base address.
+ (
+ $name:ident @ + $offset:literal $(, $comment:literal)? {
+ $($fields:tt)*
+ }
+ ) => {
+ register!(@common $name $(, $comment)?);
+ register!(@field_accessors $name { $($fields)* });
+ register!(@io$name @ + $offset);
+ };
+
+ // Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`, `BitOr`,
+ // and conversion to regular `u32`).
+ (@common $name:ident $(, $comment:literal)?) => {
+ $(
+ #[doc=$comment]
+ )?
+ #[repr(transparent)]
+ #[derive(Clone, Copy, Default)]
+ pub(crate) struct $name(u32);
+
+ // TODO: display the raw hex value, then the value of all the fields. This requires
+ // matching the fields, which will complexify the syntax considerably...
+ impl ::core::fmt::Debug for $name {
+ fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+ f.debug_tuple(stringify!($name))
+ .field(&format_args!("0x{0:x}", &self.0))
+ .finish()
+ }
+ }
+
+ impl core::ops::BitOr for $name {
+ type Output = Self;
+
+ fn bitor(self, rhs: Self) -> Self::Output {
+ Self(self.0 | rhs.0)
+ }
+ }
+
+ impl ::core::convert::From<$name> for u32 {
+ fn from(reg: $name) -> u32 {
+ reg.0
+ }
+ }
+ };
+
+ // Defines all the field getter/methods methods for `$name`.
+ (
+ @field_accessors $name:ident {
+ $($hi:tt:$lo:tt $field:ident as $type:tt
+ $(?=> $try_into_type:ty)?
+ $(=> $into_type:ty)?
+ $(, $comment:literal)?
+ ;
+ )*
+ }
+ ) => {
+ $(
+ register!(@check_field_bounds $hi:$lo $field as $type);
+ )*
+
+ #[allow(dead_code)]
+ impl $name {
+ $(
+ register!(@field_accessor $name $hi:$lo $field as $type
+ $(?=> $try_into_type)?
+ $(=> $into_type)?
+ $(, $comment)?
+ ;
+ );
+ )*
+ }
+ };
+
+ // Boolean fields must have `$hi == $lo`.
+ (@check_field_bounds $hi:tt:$lo:tt $field:ident as bool) => {
+ #[allow(clippy::eq_op)]
+ const _: () = {
+ kernel::build_assert!(
+ $hi == $lo,
+ concat!("boolean field `", stringify!($field), "` covers more than one bit")
+ );
+ };
+ };
+
+ // Non-boolean fields must have `$hi >= $lo`.
+ (@check_field_bounds $hi:tt:$lo:tt $field:ident as $type:tt) => {
+ #[allow(clippy::eq_op)]
+ const _: () = {
+ kernel::build_assert!(
+ $hi >= $lo,
+ concat!("field `", stringify!($field), "`'s MSB is smaller than its LSB")
+ );
+ };
+ };
+
+ // Catches fields defined as `bool` and convert them into a boolean value.
+ (
+ @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool => $into_type:ty
+ $(, $comment:literal)?;
+ ) => {
+ register!(
+ @leaf_accessor $name $hi:$lo $field as bool
+ { |f| <$into_type>::from(if f != 0 { true } else { false }) }
+ $into_type => $into_type $(, $comment)?;
+ );
+ };
+
+ // Shortcut for fields defined as `bool` without the `=>` syntax.
+ (
+ @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?;
+ ) => {
+ register!(@field_accessor $name $hi:$lo $field as bool => bool $(, $comment)?;);
+ };
+
+ // Catches the `?=>` syntax for non-boolean fields.
+ (
+ @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt ?=> $try_into_type:ty
+ $(, $comment:literal)?;
+ ) => {
+ register!(@leaf_accessor $name $hi:$lo $field as $type
+ { |f| <$try_into_type>::try_from(f as $type) } $try_into_type =>
+ ::core::result::Result<
+ $try_into_type,
+ <$try_into_type as ::core::convert::TryFrom<$type>>::Error
+ >
+ $(, $comment)?;);
+ };
+
+ // Catches the `=>` syntax for non-boolean fields.
+ (
+ @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty
+ $(, $comment:literal)?;
+ ) => {
+ register!(@leaf_accessor $name $hi:$lo $field as $type
+ { |f| <$into_type>::from(f as $type) } $into_type => $into_type $(, $comment)?;);
+ };
+
+ // Shortcut for fields defined as non-`bool` without the `=>` or `?=>` syntax.
+ (
+ @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt
+ $(, $comment:literal)?;
+ ) => {
+ register!(@field_accessor $name $hi:$lo $field as $type => $type $(, $comment)?;);
+ };
+
+ // Generates the accessor methods for a single field.
+ (
+ @leaf_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:ty
+ { $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?;
+ ) => {
+ kernel::macros::paste!(
+ const [<$field:upper>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi;
+ const [<$field:upper _MASK>]: u32 = ((((1 << $hi) - 1) << 1) + 1) - ((1 << $lo) - 1);
+ const [<$field:upper _SHIFT>]: u32 = Self::[<$field:upper _MASK>].trailing_zeros();
+ );
+
+ $(
+ #[doc="Returns the value of this field:"]
+ #[doc=$comment]
+ )?
+ #[inline]
+ pub(crate) fn $field(self) -> $res_type {
+ kernel::macros::paste!(
+ const MASK: u32 = $name::[<$field:upper _MASK>];
+ const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
+ );
+ let field = ((self.0 & MASK) >> SHIFT);
+
+ $process(field)
+ }
+
+ kernel::macros::paste!(
+ $(
+ #[doc="Sets the value of this field:"]
+ #[doc=$comment]
+ )?
+ #[inline]
+ pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self {
+ const MASK: u32 = $name::[<$field:upper _MASK>];
+ const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
+ let value = ((value as u32) << SHIFT) & MASK;
+ self.0 = (self.0 & !MASK) | value;
+
+ self
+ }
+ );
+ };
+
+ // Creates the IO accessors for a fixed offset register.
+ (@io $name:ident @ $offset:literal) => {
+ #[allow(dead_code)]
+ impl $name {
+ #[inline]
+ pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ Self(io.read32($offset))
+ }
+
+ #[inline]
+ pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ io.write32(self.0, $offset)
+ }
+
+ #[inline]
+ pub(crate) fn alter<const SIZE: usize, T, F>(
+ io: &T,
+ f: F,
+ ) where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ F: ::core::ops::FnOnce(Self) -> Self,
+ {
+ let reg = f(Self::read(io));
+ reg.write(io);
+ }
+ }
+ };
+
+ // Create the IO accessors for a relative offset register.
+ (@io $name:ident @ + $offset:literal) => {
+ #[allow(dead_code)]
+ impl $name {
+ #[inline]
+ pub(crate) fn read<const SIZE: usize, T>(
+ io: &T,
+ base: usize,
+ ) -> Self where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ Self(io.read32(base + $offset))
+ }
+
+ #[inline]
+ pub(crate) fn write<const SIZE: usize, T>(
+ self,
+ io: &T,
+ base: usize,
+ ) where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ io.write32(self.0, base + $offset)
+ }
+
+ #[inline]
+ pub(crate) fn alter<const SIZE: usize, T, F>(
+ io: &T,
+ base: usize,
+ f: F,
+ ) where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ F: ::core::ops::FnOnce(Self) -> Self,
+ {
+ let reg = f(Self::read(io, base));
+ reg.write(io, base);
+ }
+
+ #[inline]
+ pub(crate) fn try_read<const SIZE: usize, T>(
+ io: &T,
+ base: usize,
+ ) -> ::kernel::error::Result<Self> where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ io.try_read32(base + $offset).map(Self)
+ }
+
+ #[inline]
+ pub(crate) fn try_write<const SIZE: usize, T>(
+ self,
+ io: &T,
+ base: usize,
+ ) -> ::kernel::error::Result<()> where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ {
+ io.try_write32(self.0, base + $offset)
+ }
+
+ #[inline]
+ pub(crate) fn try_alter<const SIZE: usize, T, F>(
+ io: &T,
+ base: usize,
+ f: F,
+ ) -> ::kernel::error::Result<()> where
+ T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+ F: ::core::ops::FnOnce(Self) -> Self,
+ {
+ let reg = f(Self::try_read(io, base)?);
+ reg.try_write(io, base)
+ }
+ }
+ };
+}
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