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Message-Id: <20250930144537.3559207-3-joelagnelf@nvidia.com>
Date: Tue, 30 Sep 2025 10:45:30 -0400
From: Joel Fernandes <joelagnelf@...dia.com>
To: linux-kernel@...r.kernel.org,
rust-for-linux@...r.kernel.org,
dri-devel@...ts.freedesktop.org,
dakr@...nel.org,
acourbot@...dia.com
Cc: Alistair Popple <apopple@...dia.com>,
Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
bjorn3_gh@...tonmail.com,
Benno Lossin <lossin@...nel.org>,
Andreas Hindborg <a.hindborg@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>,
David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
John Hubbard <jhubbard@...dia.com>,
Joel Fernandes <joelagnelf@...dia.com>,
Timur Tabi <ttabi@...dia.com>,
joel@...lfernandes.org,
Elle Rhumsaa <elle@...thered-steel.dev>,
Yury Norov <yury.norov@...il.com>,
Daniel Almeida <daniel.almeida@...labora.com>,
Andrea Righi <arighi@...dia.com>,
nouveau@...ts.freedesktop.org
Subject: [PATCH v5 2/9] nova-core: bitfield: Add support for different storage widths
Previously, bitfields were hardcoded to use u32 as the underlying
storage type. Add support for different storage types (u8, u16, u32,
u64) to the bitfield macro.
New syntax is: struct Name: <type ex., u32> { ... }
Reviewed-by: Elle Rhumsaa <elle@...thered-steel.dev>
Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
---
drivers/gpu/nova-core/bitfield.rs | 210 ++++++++++++++-------------
drivers/gpu/nova-core/regs/macros.rs | 16 +-
2 files changed, 119 insertions(+), 107 deletions(-)
diff --git a/drivers/gpu/nova-core/bitfield.rs b/drivers/gpu/nova-core/bitfield.rs
index b1e1c438b8a8..75de1c0fcb3b 100644
--- a/drivers/gpu/nova-core/bitfield.rs
+++ b/drivers/gpu/nova-core/bitfield.rs
@@ -3,96 +3,99 @@
//! Bitfield library for Rust structures
//!
//! Support for defining bitfields in Rust structures. Also used by the [`register!`] macro.
-//!
-//! # Syntax
-//!
-//! ```rust
-//! use nova_core::bitfield;
-//!
-//! #[derive(Debug, Clone, Copy, Default)]
-//! enum Mode {
-//! #[default]
-//! Low = 0,
-//! High = 1,
-//! Auto = 2,
-//! }
-//!
-//! impl TryFrom<u8> for Mode {
-//! type Error = u8;
-//! fn try_from(value: u8) -> Result<Self, Self::Error> {
-//! match value {
-//! 0 => Ok(Mode::Low),
-//! 1 => Ok(Mode::High),
-//! 2 => Ok(Mode::Auto),
-//! _ => Err(value),
-//! }
-//! }
-//! }
-//!
-//! impl From<Mode> for u32 {
-//! fn from(mode: Mode) -> u32 {
-//! mode as u32
-//! }
-//! }
-//!
-//! #[derive(Debug, Clone, Copy, Default)]
-//! enum State {
-//! #[default]
-//! Inactive = 0,
-//! Active = 1,
-//! }
-//!
-//! impl From<bool> for State {
-//! fn from(value: bool) -> Self {
-//! if value { State::Active } else { State::Inactive }
-//! }
-//! }
-//!
-//! impl From<State> for u32 {
-//! fn from(state: State) -> u32 {
-//! state as u32
-//! }
-//! }
-//!
-//! bitfield! {
-//! struct ControlReg {
-//! 3:0 mode as u8 ?=> Mode;
-//! 7:7 state as bool => State;
-//! }
-//! }
-//! ```
-//!
-//! This generates a struct with:
-//! - Field accessors: `mode()`, `state()`, etc.
-//! - Field setters: `set_mode()`, `set_state()`, etc. (supports chaining with builder pattern).
-//! - Debug and Default implementations.
-//!
-//! Fields are defined as follows:
-//!
-//! - `as <type>` simply returns the field value casted to <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 with fields for which not all values are valid.
-//!
+
+/// Defines a struct with accessors to access bits within an inner unsigned integer.
+///
+/// # Syntax
+///
+/// ```rust
+/// use nova_core::bitfield;
+///
+/// #[derive(Debug, Clone, Copy, Default)]
+/// enum Mode {
+/// #[default]
+/// Low = 0,
+/// High = 1,
+/// Auto = 2,
+/// }
+///
+/// impl TryFrom<u8> for Mode {
+/// type Error = u8;
+/// fn try_from(value: u8) -> Result<Self, Self::Error> {
+/// match value {
+/// 0 => Ok(Mode::Low),
+/// 1 => Ok(Mode::High),
+/// 2 => Ok(Mode::Auto),
+/// _ => Err(value),
+/// }
+/// }
+/// }
+///
+/// impl From<Mode> for u32 {
+/// fn from(mode: Mode) -> u32 {
+/// mode as u32
+/// }
+/// }
+///
+/// #[derive(Debug, Clone, Copy, Default)]
+/// enum State {
+/// #[default]
+/// Inactive = 0,
+/// Active = 1,
+/// }
+///
+/// impl From<bool> for State {
+/// fn from(value: bool) -> Self {
+/// if value { State::Active } else { State::Inactive }
+/// }
+/// }
+///
+/// impl From<State> for u32 {
+/// fn from(state: State) -> u32 {
+/// state as u32
+/// }
+/// }
+///
+/// bitfield! {
+/// struct ControlReg(u32) {
+/// 3:0 mode as u8 ?=> Mode;
+/// 7:7 state as bool => State;
+/// }
+/// }
+/// ```
+///
+/// This generates a struct with:
+/// - Field accessors: `mode()`, `state()`, etc.
+/// - Field setters: `set_mode()`, `set_state()`, etc. (supports chaining with builder pattern).
+/// Note that the compiler will error out if the size of the setter's arg exceeds the
+/// struct's storage size.
+/// - Debug and Default implementations.
+///
+/// Fields are defined as follows:
+///
+/// - `as <type>` simply returns the field value casted to <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 with fields for which not all values are valid.
macro_rules! bitfield {
// Main entry point - defines the bitfield struct with fields
- (struct $name:ident $(, $comment:literal)? { $($fields:tt)* }) => {
- bitfield!(@core $name $(, $comment)? { $($fields)* });
+ (struct $name:ident($storage:ty) $(, $comment:literal)? { $($fields:tt)* }) => {
+ bitfield!(@core $name $storage $(, $comment)? { $($fields)* });
};
// All rules below are helpers.
// Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`,
// `Default`, `BitOr`, and conversion to the value type) and field accessor methods.
- (@core $name:ident $(, $comment:literal)? { $($fields:tt)* }) => {
+ (@core $name:ident $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
$(
#[doc=$comment]
)?
#[repr(transparent)]
#[derive(Clone, Copy)]
- pub(crate) struct $name(u32);
+ pub(crate) struct $name($storage);
impl ::core::ops::BitOr for $name {
type Output = Self;
@@ -102,20 +105,20 @@ fn bitor(self, rhs: Self) -> Self::Output {
}
}
- impl ::core::convert::From<$name> for u32 {
- fn from(val: $name) -> u32 {
+ impl ::core::convert::From<$name> for $storage {
+ fn from(val: $name) -> $storage {
val.0
}
}
- bitfield!(@fields_dispatcher $name { $($fields)* });
+ bitfield!(@fields_dispatcher $name $storage { $($fields)* });
};
// Captures the fields and passes them to all the implementers that require field information.
//
// Used to simplify the matching rules for implementers, so they don't need to match the entire
// complex fields rule even though they only make use of part of it.
- (@fields_dispatcher $name:ident {
+ (@fields_dispatcher $name:ident $storage:ty {
$($hi:tt:$lo:tt $field:ident as $type:tt
$(?=> $try_into_type:ty)?
$(=> $into_type:ty)?
@@ -124,7 +127,7 @@ fn from(val: $name) -> u32 {
)*
}
) => {
- bitfield!(@field_accessors $name {
+ bitfield!(@field_accessors $name $storage {
$(
$hi:$lo $field as $type
$(?=> $try_into_type)?
@@ -139,7 +142,7 @@ fn from(val: $name) -> u32 {
// Defines all the field getter/setter methods for `$name`.
(
- @field_accessors $name:ident {
+ @field_accessors $name:ident $storage:ty {
$($hi:tt:$lo:tt $field:ident as $type:tt
$(?=> $try_into_type:ty)?
$(=> $into_type:ty)?
@@ -155,7 +158,7 @@ fn from(val: $name) -> u32 {
#[allow(dead_code)]
impl $name {
$(
- bitfield!(@field_accessor $name $hi:$lo $field as $type
+ bitfield!(@field_accessor $name $storage, $hi:$lo $field as $type
$(?=> $try_into_type)?
$(=> $into_type)?
$(, $comment)?
@@ -189,11 +192,11 @@ impl $name {
// 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
+ @field_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident as bool => $into_type:ty
$(, $comment:literal)?;
) => {
bitfield!(
- @leaf_accessor $name $hi:$lo $field
+ @leaf_accessor $name $storage, $hi:$lo $field
{ |f| <$into_type>::from(if f != 0 { true } else { false }) }
$into_type => $into_type $(, $comment)?;
);
@@ -201,17 +204,17 @@ impl $name {
// Shortcut for fields defined as `bool` without the `=>` syntax.
(
- @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?;
+ @field_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?;
) => {
- bitfield!(@field_accessor $name $hi:$lo $field as bool => bool $(, $comment)?;);
+ bitfield!(@field_accessor $name $storage, $hi:$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
+ @field_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt ?=> $try_into_type:ty
$(, $comment:literal)?;
) => {
- bitfield!(@leaf_accessor $name $hi:$lo $field
+ bitfield!(@leaf_accessor $name $storage, $hi:$lo $field
{ |f| <$try_into_type>::try_from(f as $type) } $try_into_type =>
::core::result::Result<
$try_into_type,
@@ -222,29 +225,38 @@ impl $name {
// Catches the `=>` syntax for non-boolean fields.
(
- @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty
+ @field_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty
$(, $comment:literal)?;
) => {
- bitfield!(@leaf_accessor $name $hi:$lo $field
+ bitfield!(@leaf_accessor $name $storage, $hi:$lo $field
{ |f| <$into_type>::from(f as $type) } $into_type => $into_type $(, $comment)?;);
};
// Shortcut for non-boolean fields defined without the `=>` or `?=>` syntax.
(
- @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt
+ @field_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt
$(, $comment:literal)?;
) => {
- bitfield!(@field_accessor $name $hi:$lo $field as $type => $type $(, $comment)?;);
+ bitfield!(@field_accessor $name $storage, $hi:$lo $field as $type => $type $(, $comment)?;);
};
// Generates the accessor methods for a single field.
(
- @leaf_accessor $name:ident $hi:tt:$lo:tt $field:ident
+ @leaf_accessor $name:ident $storage:ty, $hi:tt:$lo:tt $field:ident
{ $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?;
) => {
::kernel::macros::paste!(
const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi;
- const [<$field:upper _MASK>]: u32 = ((((1 << $hi) - 1) << 1) + 1) - ((1 << $lo) - 1);
+ const [<$field:upper _MASK>]: $storage = {
+ // Generate mask for shifting
+ match ::core::mem::size_of::<$storage>() {
+ 1 => ::kernel::bits::genmask_u8($lo..=$hi) as $storage,
+ 2 => ::kernel::bits::genmask_u16($lo..=$hi) as $storage,
+ 4 => ::kernel::bits::genmask_u32($lo..=$hi) as $storage,
+ 8 => ::kernel::bits::genmask_u64($lo..=$hi) as $storage,
+ _ => ::kernel::build_error!("Unsupported storage type size")
+ }
+ };
const [<$field:upper _SHIFT>]: u32 = Self::[<$field:upper _MASK>].trailing_zeros();
);
@@ -255,7 +267,7 @@ impl $name {
#[inline(always)]
pub(crate) fn $field(self) -> $res_type {
::kernel::macros::paste!(
- const MASK: u32 = $name::[<$field:upper _MASK>];
+ const MASK: $storage = $name::[<$field:upper _MASK>];
const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
);
let field = ((self.0 & MASK) >> SHIFT);
@@ -270,9 +282,9 @@ pub(crate) fn $field(self) -> $res_type {
)?
#[inline(always)]
pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self {
- const MASK: u32 = $name::[<$field:upper _MASK>];
+ const MASK: $storage = $name::[<$field:upper _MASK>];
const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
- let value = (u32::from(value) << SHIFT) & MASK;
+ let value = (<$storage>::from(value) << SHIFT) & MASK;
self.0 = (self.0 & !MASK) | value;
self
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs
index 945d15a2c529..ffd7d5cb73bb 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/drivers/gpu/nova-core/regs/macros.rs
@@ -276,25 +276,25 @@ pub(crate) trait RegisterBase<T> {
macro_rules! register {
// Creates a register at a fixed offset of the MMIO space.
($name:ident @ $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => {
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_fixed $name @ $offset);
};
// Creates an alias register of fixed offset register `alias` with its own fields.
($name:ident => $alias:ident $(, $comment:literal)? { $($fields:tt)* } ) => {
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_fixed $name @ $alias::OFFSET);
};
// Creates a register at a relative offset from a base address provider.
($name:ident @ $base:ty [ $offset:literal ] $(, $comment:literal)? { $($fields:tt)* } ) => {
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_relative $name @ $base [ $offset ]);
};
// Creates an alias register of relative offset register `alias` with its own fields.
($name:ident => $base:ty [ $alias:ident ] $(, $comment:literal)? { $($fields:tt)* }) => {
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_relative $name @ $base [ $alias::OFFSET ]);
};
@@ -305,7 +305,7 @@ macro_rules! register {
}
) => {
static_assert!(::core::mem::size_of::<u32>() <= $stride);
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_array $name @ $offset [ $size ; $stride ]);
};
@@ -326,7 +326,7 @@ macro_rules! register {
$(, $comment:literal)? { $($fields:tt)* }
) => {
static_assert!(::core::mem::size_of::<u32>() <= $stride);
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_relative_array $name @ $base [ $offset [ $size ; $stride ] ]);
};
@@ -348,7 +348,7 @@ macro_rules! register {
}
) => {
static_assert!($idx < $alias::SIZE);
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_relative $name @ $base [ $alias::OFFSET + $idx * $alias::STRIDE ] );
};
@@ -357,7 +357,7 @@ macro_rules! register {
// to avoid it being interpreted in place of the relative register array alias rule.
($name:ident => $alias:ident [ $idx:expr ] $(, $comment:literal)? { $($fields:tt)* }) => {
static_assert!($idx < $alias::SIZE);
- bitfield!(struct $name $(, $comment)? { $($fields)* } );
+ bitfield!(struct $name(u32) $(, $comment)? { $($fields)* } );
register!(@io_fixed $name @ $alias::OFFSET + $idx * $alias::STRIDE );
};
--
2.34.1
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