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Message-Id: <20250920182232.2095101-3-joelagnelf@nvidia.com>
Date: Sat, 20 Sep 2025 14:22:28 -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>,
nouveau@...ts.freedesktop.org
Subject: [PATCH v4 2/6] 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 | 71 +++++++++++++++++-----------
drivers/gpu/nova-core/regs/macros.rs | 16 +++----
2 files changed, 52 insertions(+), 35 deletions(-)
diff --git a/drivers/gpu/nova-core/bitfield.rs b/drivers/gpu/nova-core/bitfield.rs
index ba6b7caa05d9..687ef234be75 100644
--- a/drivers/gpu/nova-core/bitfield.rs
+++ b/drivers/gpu/nova-core/bitfield.rs
@@ -51,7 +51,7 @@
//! }
//!
//! bitfield! {
-//! struct ControlReg {
+//! struct ControlReg: u32 {
//! 3:0 mode as u8 ?=> Mode;
//! 7 state as bool => State;
//! }
@@ -61,6 +61,8 @@
//! 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
//!
//! The field setters can be used with the builder pattern, example:
@@ -77,21 +79,21 @@
//!
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 $name {
type Output = Self;
@@ -101,20 +103,26 @@ fn bitor(self, rhs: Self) -> Self::Output {
}
}
- impl ::core::convert::From<$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)* });
+ impl ::core::convert::From<$storage> for $name {
+ fn from(val: $storage) -> Self {
+ Self(val)
+ }
+ }
+
+ 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)?
@@ -123,7 +131,7 @@ fn from(val: $name) -> u32 {
)*
}
) => {
- bitfield!(@field_accessors $name {
+ bitfield!(@field_accessors $name $storage {
$(
$hi:$lo $field as $type
$(?=> $try_into_type)?
@@ -138,7 +146,7 @@ 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)?
@@ -154,7 +162,7 @@ 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)?
@@ -188,11 +196,11 @@ 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)?;
);
@@ -200,17 +208,17 @@ 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,
@@ -221,29 +229,38 @@ 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();
);
@@ -254,7 +271,7 @@ 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);
@@ -269,9 +286,9 @@ 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 = (<$storage>::from(value) << SHIFT) & MASK;
self.0 = (self.0 & !MASK) | value;
self
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs
index 945d15a2c529..d34c7f37fb93 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/drivers/gpu/nova-core/regs/macros.rs
@@ -276,25 +276,25 @@ pub(crate) trait RegisterBase<T> {
macro_rules! register {
// Creates a register at a fixed offset of the MMIO space.
($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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