Out of broad need for these macros in Rust, move them out. Several folks
have shown interest (Nova, Tyr GPU drivers).

bitstruct - defines bitfields in Rust structs similar to C.
register - support for defining hardware registers and accessors.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/falcon.rs               |  2 +-
 drivers/gpu/nova-core/falcon/gsp.rs           |  3 +-
 drivers/gpu/nova-core/falcon/sec2.rs          |  2 +-
 drivers/gpu/nova-core/nova_core.rs            |  3 -
 drivers/gpu/nova-core/regs.rs                 |  5 +-
 .../nova-core => rust/kernel}/bitstruct.rs    | 31 ++++---
 rust/kernel/lib.rs                            |  2 +
 rust/kernel/prelude.rs                        |  2 +
 .../regs/macros.rs => rust/kernel/register.rs | 92 ++++++++++---------
 9 files changed, 74 insertions(+), 68 deletions(-)
 rename {drivers/gpu/nova-core => rust/kernel}/bitstruct.rs (92%)
 rename drivers/gpu/nova-core/regs/macros.rs => rust/kernel/register.rs (90%)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index be91aac6976a..06da6ce24482 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -7,6 +7,7 @@
 use kernel::bindings;
 use kernel::device;
 use kernel::prelude::*;
+use kernel::register::RegisterBase;
 use kernel::sync::aref::ARef;
 use kernel::time::Delta;
 
@@ -14,7 +15,6 @@
 use crate::driver::Bar0;
 use crate::gpu::Chipset;
 use crate::regs;
-use crate::regs::macros::RegisterBase;
 use crate::util;
 
 pub(crate) mod gsp;
diff --git a/drivers/gpu/nova-core/falcon/gsp.rs b/drivers/gpu/nova-core/falcon/gsp.rs
index f17599cb49fa..9287ab148da8 100644
--- a/drivers/gpu/nova-core/falcon/gsp.rs
+++ b/drivers/gpu/nova-core/falcon/gsp.rs
@@ -3,8 +3,9 @@
 use crate::{
     driver::Bar0,
     falcon::{Falcon, FalconEngine, PFalcon2Base, PFalconBase},
-    regs::{self, macros::RegisterBase},
+    regs,
 };
+use kernel::register::RegisterBase;
 
 /// Type specifying the `Gsp` falcon engine. Cannot be instantiated.
 pub(crate) struct Gsp(());
diff --git a/drivers/gpu/nova-core/falcon/sec2.rs b/drivers/gpu/nova-core/falcon/sec2.rs
index 815786c8480d..8f7b63b6c2b2 100644
--- a/drivers/gpu/nova-core/falcon/sec2.rs
+++ b/drivers/gpu/nova-core/falcon/sec2.rs
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 use crate::falcon::{FalconEngine, PFalcon2Base, PFalconBase};
-use crate::regs::macros::RegisterBase;
+use kernel::register::RegisterBase;
 
 /// Type specifying the `Sec2` falcon engine. Cannot be instantiated.
 pub(crate) struct Sec2(());
diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
index b218a2d42573..cb2bbb30cba1 100644
--- a/drivers/gpu/nova-core/nova_core.rs
+++ b/drivers/gpu/nova-core/nova_core.rs
@@ -2,9 +2,6 @@
 
 //! Nova Core GPU Driver
 
-#[macro_use]
-mod bitstruct;
-
 mod dma;
 mod driver;
 mod falcon;
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index 206dab2e1335..6d2f20623259 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -4,9 +4,6 @@
 // but are mapped to types.
 #![allow(non_camel_case_types)]
 
-#[macro_use]
-pub(crate) mod macros;
-
 use crate::falcon::{
     DmaTrfCmdSize, FalconCoreRev, FalconCoreRevSubversion, FalconFbifMemType, FalconFbifTarget,
     FalconModSelAlgo, FalconSecurityModel, PFalcon2Base, PFalconBase, PeregrineCoreSelect,
@@ -331,6 +328,7 @@ pub(crate) fn mem_scrubbing_done(self) -> bool {
 
 pub(crate) mod gm107 {
     // FUSE
+    use kernel::prelude::*;
 
     register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00021c04 {
         0:0     display_disabled as bool;
@@ -339,6 +337,7 @@ pub(crate) mod gm107 {
 
 pub(crate) mod ga100 {
     // FUSE
+    use kernel::prelude::*;
 
     register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00820c04 {
         0:0     display_disabled as bool;
diff --git a/drivers/gpu/nova-core/bitstruct.rs b/rust/kernel/bitstruct.rs
similarity index 92%
rename from drivers/gpu/nova-core/bitstruct.rs
rename to rust/kernel/bitstruct.rs
index 1047c5c17e2d..06e5435df383 100644
--- a/drivers/gpu/nova-core/bitstruct.rs
+++ b/rust/kernel/bitstruct.rs
@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
-//
-// bitstruct.rs — Bitfield library for Rust structures
-//
-// A library that provides support for defining bit fields in Rust
-// structures. Also used from things that need bitfields like register macro.
+
+//! Bitfield library for Rust structures
+//!
+//! A library that provides support for defining bit fields in Rust
+//! structures. Also used from things that need bitfields like register macro.
 ///
 /// # Syntax
 ///
@@ -32,6 +32,7 @@
 ///   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_export]
 macro_rules! bitstruct {
     // Main entry point - defines the bitfield struct with fields
     ($vis:vis struct $name:ident : $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
@@ -125,7 +126,7 @@ impl $name {
     (@check_field_bounds $hi:tt:$lo:tt $field:ident as bool) => {
         #[allow(clippy::eq_op)]
         const _: () = {
-            ::kernel::build_assert!(
+            build_assert!(
                 $hi == $lo,
                 concat!("boolean field `", stringify!($field), "` covers more than one bit")
             );
@@ -136,7 +137,7 @@ impl $name {
     (@check_field_bounds $hi:tt:$lo:tt $field:ident as $type:tt) => {
         #[allow(clippy::eq_op)]
         const _: () = {
-            ::kernel::build_assert!(
+            build_assert!(
                 $hi >= $lo,
                 concat!("field `", stringify!($field), "`'s MSB is smaller than its LSB")
             );
@@ -198,15 +199,15 @@ impl $name {
         @leaf_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident
             { $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?;
     ) => {
-        ::kernel::macros::paste!(
+        $crate::macros::paste!(
         const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi;
         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,
+                1 => $crate::bits::genmask_u8($lo..=$hi) as $storage,
+                2 => $crate::bits::genmask_u16($lo..=$hi) as $storage,
+                4 => $crate::bits::genmask_u32($lo..=$hi) as $storage,
+                8 => $crate::bits::genmask_u64($lo..=$hi) as $storage,
                 _ => <$storage>::MAX
             }
         };
@@ -219,7 +220,7 @@ impl $name {
         )?
         #[inline(always)]
         $vis fn $field(self) -> $res_type {
-            ::kernel::macros::paste!(
+            $crate::macros::paste!(
             const MASK: $storage = $name::[<$field:upper _MASK>];
             const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
             );
@@ -228,7 +229,7 @@ impl $name {
             $process(field)
         }
 
-        ::kernel::macros::paste!(
+        $crate::macros::paste!(
         $(
         #[doc="Sets the value of this field:"]
         #[doc=$comment]
@@ -267,7 +268,7 @@ fn default() -> Self {
                 #[allow(unused_mut)]
                 let mut value = Self(Default::default());
 
-                ::kernel::macros::paste!(
+                $crate::macros::paste!(
                 $(
                 value.[<set_ $field>](Default::default());
                 )*
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index c859a8984bae..9c492fa10967 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -64,6 +64,7 @@
 #[cfg(CONFIG_AUXILIARY_BUS)]
 pub mod auxiliary;
 pub mod bits;
+pub mod bitstruct;
 #[cfg(CONFIG_BLOCK)]
 pub mod block;
 pub mod bug;
@@ -112,6 +113,7 @@
 pub mod prelude;
 pub mod print;
 pub mod rbtree;
+pub mod register;
 pub mod regulator;
 pub mod revocable;
 pub mod security;
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index 25fe97aafd02..a98c7b7ab6af 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -39,6 +39,8 @@
 
 pub use super::static_assert;
 
+pub use super::{bitstruct, register};
+
 pub use super::error::{code::*, Error, Result};
 
 pub use super::{str::CStr, ThisModule};
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/rust/kernel/register.rs
similarity index 90%
rename from drivers/gpu/nova-core/regs/macros.rs
rename to rust/kernel/register.rs
index 22a53a73b765..1f48c5335e70 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/rust/kernel/register.rs
@@ -16,7 +16,8 @@
 /// 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(crate) trait RegisterBase<T> {
+pub trait RegisterBase<T> {
+    /// The base address for the register.
     const BASE: usize;
 }
 
@@ -281,6 +282,7 @@ pub(crate) trait RegisterBase<T> {
 /// # Ok(())
 /// # }
 /// ```
+#[macro_export]
 macro_rules! register {
     // Creates a register at a fixed offset of the MMIO space.
     ($name:ident @ $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => {
@@ -378,7 +380,7 @@ impl $name {
             /// Read the register from its address in `io`.
             #[inline(always)]
             pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 Self(io.read32($offset))
             }
@@ -386,7 +388,7 @@ pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
             /// Write the value contained in `self` to the register address in `io`.
             #[inline(always)]
             pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 io.write32(self.0, $offset)
             }
@@ -398,7 +400,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
                 io: &T,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io));
@@ -421,13 +423,13 @@ pub(crate) fn read<const SIZE: usize, T, B>(
                 #[allow(unused_variables)]
                 base: &B,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
 
                 let value = io.read32(
-                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
+                    <B as $crate::register::RegisterBase<$base>>::BASE + OFFSET
                 );
 
                 Self(value)
@@ -442,14 +444,14 @@ pub(crate) fn write<const SIZE: usize, T, B>(
                 #[allow(unused_variables)]
                 base: &B,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
 
                 io.write32(
                     self.0,
-                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
+                    <B as $crate::register::RegisterBase<$base>>::BASE + OFFSET
                 );
             }
 
@@ -462,8 +464,8 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
                 base: &B,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, base));
@@ -486,7 +488,7 @@ pub(crate) fn read<const SIZE: usize, T>(
                 io: &T,
                 idx: usize,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 build_assert!(idx < Self::SIZE);
 
@@ -503,7 +505,7 @@ pub(crate) fn write<const SIZE: usize, T>(
                 io: &T,
                 idx: usize
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 build_assert!(idx < Self::SIZE);
 
@@ -520,7 +522,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
                 idx: usize,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, idx));
@@ -535,13 +537,13 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
             pub(crate) fn try_read<const SIZE: usize, T>(
                 io: &T,
                 idx: usize,
-            ) -> ::kernel::error::Result<Self> where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+            ) -> $crate::error::Result<Self> where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 if idx < Self::SIZE {
                     Ok(Self::read(io, idx))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
 
@@ -554,13 +556,13 @@ pub(crate) fn try_write<const SIZE: usize, T>(
                 self,
                 io: &T,
                 idx: usize,
-            ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+            ) -> $crate::error::Result where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
             {
                 if idx < Self::SIZE {
                     Ok(self.write(io, idx))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
 
@@ -574,14 +576,14 @@ pub(crate) fn try_alter<const SIZE: usize, T, F>(
                 io: &T,
                 idx: usize,
                 f: F,
-            ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
+            ) -> $crate::error::Result where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 if idx < Self::SIZE {
                     Ok(Self::alter(io, idx, f))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
         }
@@ -607,12 +609,12 @@ pub(crate) fn read<const SIZE: usize, T, B>(
                 base: &B,
                 idx: usize,
             ) -> Self where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
 
-                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
+                let offset = <B as $crate::register::RegisterBase<$base>>::BASE +
                     Self::OFFSET + (idx * Self::STRIDE);
                 let value = io.read32(offset);
 
@@ -629,12 +631,12 @@ pub(crate) fn write<const SIZE: usize, T, B>(
                 base: &B,
                 idx: usize
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
 
-                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
+                let offset = <B as $crate::register::RegisterBase<$base>>::BASE +
                     Self::OFFSET + (idx * Self::STRIDE);
 
                 io.write32(self.0, offset);
@@ -650,8 +652,8 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
                 idx: usize,
                 f: F,
             ) where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, base, idx));
@@ -668,14 +670,14 @@ pub(crate) fn try_read<const SIZE: usize, T, B>(
                 io: &T,
                 base: &B,
                 idx: usize,
-            ) -> ::kernel::error::Result<Self> where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+            ) -> $crate::error::Result<Self> where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
                     Ok(Self::read(io, base, idx))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
 
@@ -690,14 +692,14 @@ pub(crate) fn try_write<const SIZE: usize, T, B>(
                 io: &T,
                 base: &B,
                 idx: usize,
-            ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+            ) -> $crate::error::Result where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
                     Ok(self.write(io, base, idx))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
 
@@ -713,17 +715,19 @@ pub(crate) fn try_alter<const SIZE: usize, T, B, F>(
                 base: &B,
                 idx: usize,
                 f: F,
-            ) -> ::kernel::error::Result where
-                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+            ) -> $crate::error::Result where
+                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
+                B: $crate::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 if idx < Self::SIZE {
                     Ok(Self::alter(io, base, idx, f))
                 } else {
-                    Err(EINVAL)
+                    Err($crate::error::code::EINVAL)
                 }
             }
         }
     };
 }
+
+pub use register;
-- 
2.34.1

On Thu Sep 4, 2025 at 6:54 AM JST, Joel Fernandes wrote:
> Out of broad need for these macros in Rust, move them out. Several folks
> have shown interest (Nova, Tyr GPU drivers).
>
> bitstruct - defines bitfields in Rust structs similar to C.
> register - support for defining hardware registers and accessors.
>
> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
<snip>

> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index c859a8984bae..9c492fa10967 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -64,6 +64,7 @@
>  #[cfg(CONFIG_AUXILIARY_BUS)]
>  pub mod auxiliary;
>  pub mod bits;
> +pub mod bitstruct;
>  #[cfg(CONFIG_BLOCK)]
>  pub mod block;
>  pub mod bug;
> @@ -112,6 +113,7 @@
>  pub mod prelude;
>  pub mod print;
>  pub mod rbtree;
> +pub mod register;

I remember a discussion with Danilo where he mentioned the register
macro should end up being in `kernel::io::register`.

Also wondering whether `bitstruct` should not be in the
appropriately-named `bits` module standing right above it. :)

On Mon, Sep 08, 2025 at 12:52:57PM +0900, Alexandre Courbot wrote:
> On Thu Sep 4, 2025 at 6:54 AM JST, Joel Fernandes wrote:
> > Out of broad need for these macros in Rust, move them out. Several folks
> > have shown interest (Nova, Tyr GPU drivers).
> >
> > bitstruct - defines bitfields in Rust structs similar to C.
> > register - support for defining hardware registers and accessors.
> >
> > Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
> <snip>
> 
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index c859a8984bae..9c492fa10967 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -64,6 +64,7 @@
> >  #[cfg(CONFIG_AUXILIARY_BUS)]
> >  pub mod auxiliary;
> >  pub mod bits;
> > +pub mod bitstruct;
> >  #[cfg(CONFIG_BLOCK)]
> >  pub mod block;
> >  pub mod bug;
> > @@ -112,6 +113,7 @@
> >  pub mod prelude;
> >  pub mod print;
> >  pub mod rbtree;
> > +pub mod register;
> 
> I remember a discussion with Danilo where he mentioned the register
> macro should end up being in `kernel::io::register`.

I talked with Danilo, and I moved it to io for next revision.

> Also wondering whether `bitstruct` should not be in the
> appropriately-named `bits` module standing right above it. :)

I think now that I renamed it to bitfield, I'll move it to bits. That does
make a lot of sense.

thanks,

 - Joel

Hi Joel,

I didn't check the macros, but a couple nits I noticed in this patch
in particular given it moved it to `kernel`...

On Wed, Sep 3, 2025 at 11:54 PM Joel Fernandes <joelagnelf@nvidia.com> wrote:
>
> +//! A library that provides support for defining bit fields in Rust

What about just "Support for defining bit fields in ..." or similar?

> +//! structures. Also used from things that need bitfields like register macro.

The "register macro" part sounds like it should be formatted with
Markdown plus an intra-doc link.

> -            ::kernel::build_assert!(
> +            build_assert!(

Is this path unqualified for some reason? Does it mean the user needs
to have imported the prelude?

> +pub use super::{bitstruct, register};

Please justify in the commit message why we want them in the prelude,
e.g. are they expected to be common? Does it simplify some code? etc.

Thanks!

Cheers,
Miguel

On 9/7/2025 2:14 PM, Miguel Ojeda wrote:
> Hi Joel,
> 
> I didn't check the macros, but a couple nits I noticed in this patch
> in particular given it moved it to `kernel`...
> 
> On Wed, Sep 3, 2025 at 11:54 PM Joel Fernandes <joelagnelf@nvidia.com> wrote:
>>
>> +//! A library that provides support for defining bit fields in Rust
> 
> What about just "Support for defining bit fields in ..." or similar?
> 
>> +//! structures. Also used from things that need bitfields like register macro.

Ok, I changed it to:
"Also used from things that need bitfields like [`register!`] macro." for next
revision.

> 
> The "register macro" part sounds like it should be formatted with
> Markdown plus an intra-doc link.
> 
>> -            ::kernel::build_assert!(
>> +            build_assert!(
> 
> Is this path unqualified for some reason? Does it mean the user needs
> to have imported the prelude?

Yes, for register macro importing prelude is required (I commented more below).

> 
>> +pub use super::{bitstruct, register};
> 
> Please justify in the commit message why we want them in the prelude,
> e.g. are they expected to be common? Does it simplify some code? etc.
> 
The issue I ran into is, without adding it to prelude, the users of register!
macro will have to import both bitfield! and register! macros explictly, even
though they're only using register!. I tried to make it work without adding to
prelude, but couldn't:

  use kernel::{bitfield, register};

Also not adding it to prelude, means register! macro has to invoke bitfield with
$crate prefixed  ($crate::bitfield).

I think the prelude-way is clean, but let me know if there's any other trick I
can try.

I will also add this rationale to the commit message as you suggested.

Thanks!

 - Joel

On Mon, Sep 8, 2025 at 7:06 PM Joel Fernandes <joelagnelf@nvidia.com> wrote:
>
> The issue I ran into is, without adding it to prelude, the users of register!
> macro will have to import both bitfield! and register! macros explictly, even
> though they're only using register!. I tried to make it work without adding to
> prelude, but couldn't:
>
>   use kernel::{bitfield, register};
>
> Also not adding it to prelude, means register! macro has to invoke bitfield with
> $crate prefixed  ($crate::bitfield).

I am not sure I follow -- macros should use qualified paths in general
so that they assume as little as possible from the calling
environment.

It should work without the prelude -- what didn't work?

Thanks!

Cheers,
Miguel

On Mon, Sep 08, 2025 at 08:39:19PM +0200, Miguel Ojeda wrote:
> On Mon, Sep 8, 2025 at 7:06 PM Joel Fernandes <joelagnelf@nvidia.com> wrote:
> >
> > The issue I ran into is, without adding it to prelude, the users of register!
> > macro will have to import both bitfield! and register! macros explictly, even
> > though they're only using register!. I tried to make it work without adding to
> > prelude, but couldn't:
> >
> >   use kernel::{bitfield, register};
> >
> > Also not adding it to prelude, means register! macro has to invoke bitfield with
> > $crate prefixed  ($crate::bitfield).
> 
> I am not sure I follow -- macros should use qualified paths in general
> so that they assume as little as possible from the calling
> environment.

It works! Can you look if the below looks good to you now? No more prelude. Thanks!

---8<----

From: Joel Fernandes <joelagnelf@nvidia.com>
Subject: [PATCH] rust: Move register and bitfield macros out of Nova

Out of broad need for these macros in Rust, move them out. Several folks
have shown interest (Nova, Tyr GPU drivers).

bitfield moved into bits modules - defines bitfields in Rust structs similar to C.
register moved into io module - defines hardware registers and accessors.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/falcon.rs               |  2 +-
 drivers/gpu/nova-core/falcon/gsp.rs           |  3 +-
 drivers/gpu/nova-core/falcon/sec2.rs          |  2 +-
 drivers/gpu/nova-core/nova_core.rs            |  3 --
 drivers/gpu/nova-core/regs.rs                 |  6 +--
 rust/kernel/bits.rs                           |  2 +
 .../kernel/bits}/bitfield.rs                  | 27 ++++++-----
 rust/kernel/io.rs                             |  1 +
 .../macros.rs => rust/kernel/io/register.rs   | 48 ++++++++++---------
 9 files changed, 50 insertions(+), 44 deletions(-)
 rename {drivers/gpu/nova-core => rust/kernel/bits}/bitfield.rs (90%)
 rename drivers/gpu/nova-core/regs/macros.rs => rust/kernel/io/register.rs (93%)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index 938f25b556a8..c69bc2adb33c 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -7,6 +7,7 @@
 use kernel::device;
 use kernel::dma::DmaAddress;
 use kernel::prelude::*;
+use kernel::io::register::RegisterBase;
 use kernel::sync::aref::ARef;
 use kernel::time::Delta;
 
@@ -14,7 +15,6 @@
 use crate::driver::Bar0;
 use crate::gpu::Chipset;
 use crate::regs;
-use crate::regs::macros::RegisterBase;
 use crate::util;
 
 pub(crate) mod gsp;
diff --git a/drivers/gpu/nova-core/falcon/gsp.rs b/drivers/gpu/nova-core/falcon/gsp.rs
index c9ab375fd8a1..f315344b4256 100644
--- a/drivers/gpu/nova-core/falcon/gsp.rs
+++ b/drivers/gpu/nova-core/falcon/gsp.rs
@@ -1,12 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
 
 use kernel::prelude::*;
+use kernel::io::register::RegisterBase;
 use kernel::time::Delta;
 
 use crate::{
     driver::Bar0,
     falcon::{Falcon, FalconEngine, PFalcon2Base, PFalconBase},
-    regs::{self, macros::RegisterBase},
+    regs,
     util::wait_on,
 };
 
diff --git a/drivers/gpu/nova-core/falcon/sec2.rs b/drivers/gpu/nova-core/falcon/sec2.rs
index 815786c8480d..81717868a8a8 100644
--- a/drivers/gpu/nova-core/falcon/sec2.rs
+++ b/drivers/gpu/nova-core/falcon/sec2.rs
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 use crate::falcon::{FalconEngine, PFalcon2Base, PFalconBase};
-use crate::regs::macros::RegisterBase;
+use kernel::io::register::RegisterBase;
 
 /// Type specifying the `Sec2` falcon engine. Cannot be instantiated.
 pub(crate) struct Sec2(());
diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
index eaba6ad22f7a..4dbc7e5daae3 100644
--- a/drivers/gpu/nova-core/nova_core.rs
+++ b/drivers/gpu/nova-core/nova_core.rs
@@ -2,9 +2,6 @@
 
 //! Nova Core GPU Driver
 
-#[macro_use]
-mod bitfield;
-
 mod dma;
 mod driver;
 mod falcon;
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index c214f8056d6e..07533eb6f64e 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -4,15 +4,13 @@
 // but are mapped to types.
 #![allow(non_camel_case_types)]
 
-#[macro_use]
-pub(crate) mod macros;
-
 use crate::falcon::{
     DmaTrfCmdSize, FalconCoreRev, FalconCoreRevSubversion, FalconFbifMemType, FalconFbifTarget,
     FalconModSelAlgo, FalconSecurityModel, PFalcon2Base, PFalconBase, PeregrineCoreSelect,
 };
 use crate::gpu::{Architecture, Chipset};
 use kernel::prelude::*;
+use kernel::register;
 
 // PMC
 
@@ -352,6 +350,7 @@ pub(crate) fn mem_scrubbing_done(self) -> bool {
 
 pub(crate) mod gm107 {
     // FUSE
+    use kernel::register;
 
     register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00021c04 {
         0:0     display_disabled as bool;
@@ -360,6 +359,7 @@ pub(crate) mod gm107 {
 
 pub(crate) mod ga100 {
     // FUSE
+    use kernel::register;
 
     register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00820c04 {
         0:0     display_disabled as bool;
diff --git a/rust/kernel/bits.rs b/rust/kernel/bits.rs
index 553d50265883..590a77d99ad7 100644
--- a/rust/kernel/bits.rs
+++ b/rust/kernel/bits.rs
@@ -201,3 +201,5 @@ pub const fn [<genmask_ $ty>](range: RangeInclusive<u32>) -> $ty {
     /// assert_eq!(genmask_u8(0..=7), u8::MAX);
     /// ```
 );
+
+pub mod bitfield;
diff --git a/drivers/gpu/nova-core/bitfield.rs b/rust/kernel/bits/bitfield.rs
similarity index 90%
rename from drivers/gpu/nova-core/bitfield.rs
rename to rust/kernel/bits/bitfield.rs
index 2ca5f3725246..b49bfc1abcd5 100644
--- a/drivers/gpu/nova-core/bitfield.rs
+++ b/rust/kernel/bits/bitfield.rs
@@ -33,10 +33,13 @@
 //! - `as <type> ?=> <try_into_type>` calls `<try_into_type>`'s `TryFrom::<<type>>` implementation
 //!   and returns the result. This is useful with fields for which not all values are valid.
 //!
+
+/// bitfield macro definition
+#[macro_export]
 macro_rules! bitfield {
     // Main entry point - defines the bitfield struct with fields
     ($vis:vis struct $name:ident : $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
-        bitfield!(@core $name $vis $storage $(, $comment)? { $($fields)* });
+        ::kernel::bitfield!(@core $name $vis $storage $(, $comment)? { $($fields)* });
     };
 
     // All rules below are helpers.
@@ -71,7 +74,7 @@ fn from(val: $storage) -> Self {
             }
         }
 
-        bitfield!(@fields_dispatcher $name $vis $storage { $($fields)* });
+        ::kernel::bitfield!(@fields_dispatcher $name $vis $storage { $($fields)* });
     };
 
     // Captures the fields and passes them to all the implementers that require field information.
@@ -87,7 +90,7 @@ fn from(val: $storage) -> Self {
         )*
     }
     ) => {
-        bitfield!(@field_accessors $name $vis $storage {
+        ::kernel::bitfield!(@field_accessors $name $vis $storage {
             $(
                 $hi:$lo $field as $type
                 $(?=> $try_into_type)?
@@ -96,8 +99,8 @@ fn from(val: $storage) -> Self {
             ;
             )*
         });
-        bitfield!(@debug $name $storage { $($field;)* });
-        bitfield!(@default $name $storage { $($field;)* });
+        ::kernel::bitfield!(@debug $name $storage { $($field;)* });
+        ::kernel::bitfield!(@default $name $storage { $($field;)* });
     };
 
     // Defines all the field getter/setter methods for `$name`.
@@ -112,7 +115,7 @@ fn from(val: $storage) -> Self {
         }
     ) => {
         $(
-            bitfield!(@check_field_bounds $hi:$lo $field as $type);
+            ::kernel::bitfield!(@check_field_bounds $hi:$lo $field as $type);
         )*
 
         #[allow(dead_code)]
@@ -124,7 +127,7 @@ impl $name {
             }
 
             $(
-            bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as $type
+            ::kernel::bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as $type
                 $(?=> $try_into_type)?
                 $(=> $into_type)?
                 $(, $comment)?
@@ -161,7 +164,7 @@ impl $name {
         @field_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident as bool => $into_type:ty
             $(, $comment:literal)?;
     ) => {
-        bitfield!(
+        ::kernel::bitfield!(
             @leaf_accessor $name $vis $storage, $hi:$lo $field
             { |f| <$into_type>::from(if f != 0 { true } else { false }) }
             $into_type => $into_type $(, $comment)?;
@@ -172,7 +175,7 @@ impl $name {
     (
         @field_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?;
     ) => {
-        bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as bool => bool $(, $comment)?;);
+        ::kernel::bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as bool => bool $(, $comment)?;);
     };
 
     // Catches the `?=>` syntax for non-boolean fields.
@@ -180,7 +183,7 @@ impl $name {
         @field_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt ?=> $try_into_type:ty
             $(, $comment:literal)?;
     ) => {
-        bitfield!(@leaf_accessor $name $vis $storage, $hi:$lo $field
+        ::kernel::bitfield!(@leaf_accessor $name $vis $storage, $hi:$lo $field
             { |f| <$try_into_type>::try_from(f as $type) } $try_into_type =>
             ::core::result::Result<
                 $try_into_type,
@@ -194,7 +197,7 @@ impl $name {
         @field_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty
             $(, $comment:literal)?;
     ) => {
-        bitfield!(@leaf_accessor $name $vis $storage, $hi:$lo $field
+        ::kernel::bitfield!(@leaf_accessor $name $vis $storage, $hi:$lo $field
             { |f| <$into_type>::from(f as $type) } $into_type => $into_type $(, $comment)?;);
     };
 
@@ -203,7 +206,7 @@ impl $name {
         @field_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident as $type:tt
             $(, $comment:literal)?;
     ) => {
-        bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as $type => $type $(, $comment)?;);
+        ::kernel::bitfield!(@field_accessor $name $vis $storage, $hi:$lo $field as $type => $type $(, $comment)?;);
     };
 
     // Generates the accessor methods for a single field.
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index 03b467722b86..a79b603604b1 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -8,6 +8,7 @@
 use crate::{bindings, build_assert, ffi::c_void};
 
 pub mod mem;
+pub mod register;
 pub mod resource;
 
 pub use resource::Resource;
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/rust/kernel/io/register.rs
similarity index 93%
rename from drivers/gpu/nova-core/regs/macros.rs
rename to rust/kernel/io/register.rs
index fab407c50668..a212b12de0f1 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/rust/kernel/io/register.rs
@@ -16,7 +16,8 @@
 /// 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(crate) trait RegisterBase<T> {
+pub trait RegisterBase<T> {
+    /// The base address for the register.
     const BASE: usize;
 }
 
@@ -55,7 +56,7 @@ pub(crate) trait RegisterBase<T> {
 /// ```
 ///
 ///
-/// Please look at the [`bitfield`] macro for the complete syntax of fields definitions.
+/// Please look at the [`bitfield`][crate::bits::bitfield::bitfield] macro for the complete syntax of fields definitions.
 ///
 /// 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.
@@ -275,28 +276,29 @@ pub(crate) trait RegisterBase<T> {
 /// # Ok(())
 /// # }
 /// ```
+#[macro_export]
 macro_rules! register {
     // Creates a register at a fixed offset of the MMIO space.
     ($name:ident @ $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => {
-        bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) 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!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) 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!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) 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!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
         register!(@io_relative $name @ $base [ $alias::OFFSET ]);
     };
 
@@ -307,7 +309,7 @@ macro_rules! register {
         }
     ) => {
         static_assert!(::core::mem::size_of::<u32>() <= $stride);
-        bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
         register!(@io_array $name @ $offset [ $size ; $stride ]);
     };
 
@@ -328,7 +330,7 @@ macro_rules! register {
             $(, $comment:literal)? { $($fields:tt)* }
     ) => {
         static_assert!(::core::mem::size_of::<u32>() <= $stride);
-        bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
         register!(@io_relative_array $name @ $base [ $offset [ $size ; $stride ] ]);
     };
 
@@ -350,7 +352,7 @@ macro_rules! register {
         }
     ) => {
         static_assert!($idx < $alias::SIZE);
-        bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
         register!(@io_relative $name @ $base [ $alias::OFFSET + $idx * $alias::STRIDE ] );
     };
 
@@ -359,7 +361,7 @@ 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!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
+        ::kernel::bitfield!(pub(crate) struct $name: u32 $(, $comment)? { $($fields)* } );
         register!(@io_fixed $name @ $alias::OFFSET + $idx * $alias::STRIDE );
     };
 
@@ -416,12 +418,12 @@ pub(crate) fn read<const SIZE: usize, T, B>(
                 base: &B,
             ) -> Self where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
 
                 let value = io.read32(
-                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
+                    <B as ::kernel::io::register::RegisterBase<$base>>::BASE + OFFSET
                 );
 
                 Self(value)
@@ -437,13 +439,13 @@ pub(crate) fn write<const SIZE: usize, T, B>(
                 base: &B,
             ) where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 const OFFSET: usize = $name::OFFSET;
 
                 io.write32(
                     self.0,
-                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
+                    <B as ::kernel::io::register::RegisterBase<$base>>::BASE + OFFSET
                 );
             }
 
@@ -457,7 +459,7 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
                 f: F,
             ) where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, base));
@@ -602,11 +604,11 @@ pub(crate) fn read<const SIZE: usize, T, B>(
                 idx: usize,
             ) -> Self where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
 
-                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
+                let offset = <B as ::kernel::io::register::RegisterBase<$base>>::BASE +
                     Self::OFFSET + (idx * Self::STRIDE);
                 let value = io.read32(offset);
 
@@ -624,11 +626,11 @@ pub(crate) fn write<const SIZE: usize, T, B>(
                 idx: usize
             ) where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 build_assert!(idx < Self::SIZE);
 
-                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
+                let offset = <B as ::kernel::io::register::RegisterBase<$base>>::BASE +
                     Self::OFFSET + (idx * Self::STRIDE);
 
                 io.write32(self.0, offset);
@@ -645,7 +647,7 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
                 f: F,
             ) where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 let reg = f(Self::read(io, base, idx));
@@ -664,7 +666,7 @@ pub(crate) fn try_read<const SIZE: usize, T, B>(
                 idx: usize,
             ) -> ::kernel::error::Result<Self> where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
                     Ok(Self::read(io, base, idx))
@@ -686,7 +688,7 @@ pub(crate) fn try_write<const SIZE: usize, T, B>(
                 idx: usize,
             ) -> ::kernel::error::Result where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
             {
                 if idx < Self::SIZE {
                     Ok(self.write(io, base, idx))
@@ -709,7 +711,7 @@ pub(crate) fn try_alter<const SIZE: usize, T, B, F>(
                 f: F,
             ) -> ::kernel::error::Result where
                 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
-                B: crate::regs::macros::RegisterBase<$base>,
+                B: ::kernel::io::register::RegisterBase<$base>,
                 F: ::core::ops::FnOnce(Self) -> Self,
             {
                 if idx < Self::SIZE {
-- 
2.34.1

On 9/8/2025 2:39 PM, Miguel Ojeda wrote:
> On Mon, Sep 8, 2025 at 7:06 PM Joel Fernandes <joelagnelf@nvidia.com> wrote:
>>
>> The issue I ran into is, without adding it to prelude, the users of register!
>> macro will have to import both bitfield! and register! macros explictly, even
>> though they're only using register!. I tried to make it work without adding to
>> prelude, but couldn't:
>>
>>   use kernel::{bitfield, register};
>>
>> Also not adding it to prelude, means register! macro has to invoke bitfield with
>> $crate prefixed  ($crate::bitfield).
> 
> I am not sure I follow -- macros should use qualified paths in general
> so that they assume as little as possible from the calling
> environment.
> 
> It should work without the prelude -- what didn't work?

Ah, I guess my intent was to not use the qualified path. But that's better than
the users having to import prelude. Ok, thanks! - I will try this out.

 - Joel

> 
> Thanks!
> 
> Cheers,
> Miguel

On Wed, Sep 03, 2025 at 05:54:28PM -0400, Joel Fernandes wrote:
> Out of broad need for these macros in Rust, move them out. Several folks
> have shown interest (Nova, Tyr GPU drivers).
> 
> bitstruct - defines bitfields in Rust structs similar to C.
> register - support for defining hardware registers and accessors.
> 
> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
> ---
>  drivers/gpu/nova-core/falcon.rs               |  2 +-
>  drivers/gpu/nova-core/falcon/gsp.rs           |  3 +-
>  drivers/gpu/nova-core/falcon/sec2.rs          |  2 +-
>  drivers/gpu/nova-core/nova_core.rs            |  3 -
>  drivers/gpu/nova-core/regs.rs                 |  5 +-
>  .../nova-core => rust/kernel}/bitstruct.rs    | 31 ++++---
>  rust/kernel/lib.rs                            |  2 +
>  rust/kernel/prelude.rs                        |  2 +
>  .../regs/macros.rs => rust/kernel/register.rs | 92 ++++++++++---------
>  9 files changed, 74 insertions(+), 68 deletions(-)
>  rename {drivers/gpu/nova-core => rust/kernel}/bitstruct.rs (92%)
>  rename drivers/gpu/nova-core/regs/macros.rs => rust/kernel/register.rs (90%)
> 
> diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
> index be91aac6976a..06da6ce24482 100644
> --- a/drivers/gpu/nova-core/falcon.rs
> +++ b/drivers/gpu/nova-core/falcon.rs
> @@ -7,6 +7,7 @@
>  use kernel::bindings;
>  use kernel::device;
>  use kernel::prelude::*;
> +use kernel::register::RegisterBase;
>  use kernel::sync::aref::ARef;
>  use kernel::time::Delta;
>  
> @@ -14,7 +15,6 @@
>  use crate::driver::Bar0;
>  use crate::gpu::Chipset;
>  use crate::regs;
> -use crate::regs::macros::RegisterBase;
>  use crate::util;
>  
>  pub(crate) mod gsp;
> diff --git a/drivers/gpu/nova-core/falcon/gsp.rs b/drivers/gpu/nova-core/falcon/gsp.rs
> index f17599cb49fa..9287ab148da8 100644
> --- a/drivers/gpu/nova-core/falcon/gsp.rs
> +++ b/drivers/gpu/nova-core/falcon/gsp.rs
> @@ -3,8 +3,9 @@
>  use crate::{
>      driver::Bar0,
>      falcon::{Falcon, FalconEngine, PFalcon2Base, PFalconBase},
> -    regs::{self, macros::RegisterBase},
> +    regs,
>  };
> +use kernel::register::RegisterBase;
>  
>  /// Type specifying the `Gsp` falcon engine. Cannot be instantiated.
>  pub(crate) struct Gsp(());
> diff --git a/drivers/gpu/nova-core/falcon/sec2.rs b/drivers/gpu/nova-core/falcon/sec2.rs
> index 815786c8480d..8f7b63b6c2b2 100644
> --- a/drivers/gpu/nova-core/falcon/sec2.rs
> +++ b/drivers/gpu/nova-core/falcon/sec2.rs
> @@ -1,7 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
>  use crate::falcon::{FalconEngine, PFalcon2Base, PFalconBase};
> -use crate::regs::macros::RegisterBase;
> +use kernel::register::RegisterBase;
>  
>  /// Type specifying the `Sec2` falcon engine. Cannot be instantiated.
>  pub(crate) struct Sec2(());
> diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
> index b218a2d42573..cb2bbb30cba1 100644
> --- a/drivers/gpu/nova-core/nova_core.rs
> +++ b/drivers/gpu/nova-core/nova_core.rs
> @@ -2,9 +2,6 @@
>  
>  //! Nova Core GPU Driver
>  
> -#[macro_use]
> -mod bitstruct;
> -
>  mod dma;
>  mod driver;
>  mod falcon;
> diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
> index 206dab2e1335..6d2f20623259 100644
> --- a/drivers/gpu/nova-core/regs.rs
> +++ b/drivers/gpu/nova-core/regs.rs
> @@ -4,9 +4,6 @@
>  // but are mapped to types.
>  #![allow(non_camel_case_types)]
>  
> -#[macro_use]
> -pub(crate) mod macros;
> -
>  use crate::falcon::{
>      DmaTrfCmdSize, FalconCoreRev, FalconCoreRevSubversion, FalconFbifMemType, FalconFbifTarget,
>      FalconModSelAlgo, FalconSecurityModel, PFalcon2Base, PFalconBase, PeregrineCoreSelect,
> @@ -331,6 +328,7 @@ pub(crate) fn mem_scrubbing_done(self) -> bool {
>  
>  pub(crate) mod gm107 {
>      // FUSE
> +    use kernel::prelude::*;
>  
>      register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00021c04 {
>          0:0     display_disabled as bool;
> @@ -339,6 +337,7 @@ pub(crate) mod gm107 {
>  
>  pub(crate) mod ga100 {
>      // FUSE
> +    use kernel::prelude::*;
>  
>      register!(NV_FUSE_STATUS_OPT_DISPLAY @ 0x00820c04 {
>          0:0     display_disabled as bool;
> diff --git a/drivers/gpu/nova-core/bitstruct.rs b/rust/kernel/bitstruct.rs
> similarity index 92%
> rename from drivers/gpu/nova-core/bitstruct.rs
> rename to rust/kernel/bitstruct.rs
> index 1047c5c17e2d..06e5435df383 100644
> --- a/drivers/gpu/nova-core/bitstruct.rs
> +++ b/rust/kernel/bitstruct.rs
> @@ -1,9 +1,9 @@
>  // SPDX-License-Identifier: GPL-2.0
> -//
> -// bitstruct.rs — Bitfield library for Rust structures
> -//
> -// A library that provides support for defining bit fields in Rust
> -// structures. Also used from things that need bitfields like register macro.
> +
> +//! Bitfield library for Rust structures
> +//!
> +//! A library that provides support for defining bit fields in Rust
> +//! structures. Also used from things that need bitfields like register macro.
>  ///
>  /// # Syntax
>  ///
> @@ -32,6 +32,7 @@
>  ///   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_export]
>  macro_rules! bitstruct {
>      // Main entry point - defines the bitfield struct with fields
>      ($vis:vis struct $name:ident : $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
> @@ -125,7 +126,7 @@ impl $name {
>      (@check_field_bounds $hi:tt:$lo:tt $field:ident as bool) => {
>          #[allow(clippy::eq_op)]
>          const _: () = {
> -            ::kernel::build_assert!(
> +            build_assert!(
>                  $hi == $lo,
>                  concat!("boolean field `", stringify!($field), "` covers more than one bit")
>              );
> @@ -136,7 +137,7 @@ impl $name {
>      (@check_field_bounds $hi:tt:$lo:tt $field:ident as $type:tt) => {
>          #[allow(clippy::eq_op)]
>          const _: () = {
> -            ::kernel::build_assert!(
> +            build_assert!(
>                  $hi >= $lo,
>                  concat!("field `", stringify!($field), "`'s MSB is smaller than its LSB")
>              );
> @@ -198,15 +199,15 @@ impl $name {
>          @leaf_accessor $name:ident $vis:vis $storage:ty, $hi:tt:$lo:tt $field:ident
>              { $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?;
>      ) => {
> -        ::kernel::macros::paste!(
> +        $crate::macros::paste!(
>          const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi;
>          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,
> +                1 => $crate::bits::genmask_u8($lo..=$hi) as $storage,
> +                2 => $crate::bits::genmask_u16($lo..=$hi) as $storage,
> +                4 => $crate::bits::genmask_u32($lo..=$hi) as $storage,
> +                8 => $crate::bits::genmask_u64($lo..=$hi) as $storage,
>                  _ => <$storage>::MAX
>              }
>          };
> @@ -219,7 +220,7 @@ impl $name {
>          )?
>          #[inline(always)]
>          $vis fn $field(self) -> $res_type {
> -            ::kernel::macros::paste!(
> +            $crate::macros::paste!(
>              const MASK: $storage = $name::[<$field:upper _MASK>];
>              const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
>              );
> @@ -228,7 +229,7 @@ impl $name {
>              $process(field)
>          }
>  
> -        ::kernel::macros::paste!(
> +        $crate::macros::paste!(
>          $(
>          #[doc="Sets the value of this field:"]
>          #[doc=$comment]
> @@ -267,7 +268,7 @@ fn default() -> Self {
>                  #[allow(unused_mut)]
>                  let mut value = Self(Default::default());
>  
> -                ::kernel::macros::paste!(
> +                $crate::macros::paste!(
>                  $(
>                  value.[<set_ $field>](Default::default());
>                  )*
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index c859a8984bae..9c492fa10967 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -64,6 +64,7 @@
>  #[cfg(CONFIG_AUXILIARY_BUS)]
>  pub mod auxiliary;
>  pub mod bits;
> +pub mod bitstruct;
>  #[cfg(CONFIG_BLOCK)]
>  pub mod block;
>  pub mod bug;
> @@ -112,6 +113,7 @@
>  pub mod prelude;
>  pub mod print;
>  pub mod rbtree;
> +pub mod register;
>  pub mod regulator;
>  pub mod revocable;
>  pub mod security;
> diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
> index 25fe97aafd02..a98c7b7ab6af 100644
> --- a/rust/kernel/prelude.rs
> +++ b/rust/kernel/prelude.rs
> @@ -39,6 +39,8 @@
>  
>  pub use super::static_assert;
>  
> +pub use super::{bitstruct, register};
> +
>  pub use super::error::{code::*, Error, Result};
>  
>  pub use super::{str::CStr, ThisModule};
> diff --git a/drivers/gpu/nova-core/regs/macros.rs b/rust/kernel/register.rs
> similarity index 90%
> rename from drivers/gpu/nova-core/regs/macros.rs
> rename to rust/kernel/register.rs
> index 22a53a73b765..1f48c5335e70 100644
> --- a/drivers/gpu/nova-core/regs/macros.rs
> +++ b/rust/kernel/register.rs
> @@ -16,7 +16,8 @@
>  /// The `T` generic argument is used to distinguish which base to use, in case a type provides
>  /// several bases. It is given to the `register!` macro to restrict the use of the register to
>  /// implementors of this particular variant.
> -pub(crate) trait RegisterBase<T> {
> +pub trait RegisterBase<T> {
> +    /// The base address for the register.
>      const BASE: usize;
>  }
>  
> @@ -281,6 +282,7 @@ pub(crate) trait RegisterBase<T> {
>  /// # Ok(())
>  /// # }
>  /// ```
> +#[macro_export]
>  macro_rules! register {
>      // Creates a register at a fixed offset of the MMIO space.
>      ($name:ident @ $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => {
> @@ -378,7 +380,7 @@ impl $name {
>              /// Read the register from its address in `io`.
>              #[inline(always)]
>              pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  Self(io.read32($offset))
>              }
> @@ -386,7 +388,7 @@ pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where
>              /// Write the value contained in `self` to the register address in `io`.
>              #[inline(always)]
>              pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  io.write32(self.0, $offset)
>              }
> @@ -398,7 +400,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
>                  io: &T,
>                  f: F,
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  let reg = f(Self::read(io));
> @@ -421,13 +423,13 @@ pub(crate) fn read<const SIZE: usize, T, B>(
>                  #[allow(unused_variables)]
>                  base: &B,
>              ) -> Self where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  const OFFSET: usize = $name::OFFSET;
>  
>                  let value = io.read32(
> -                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
> +                    <B as $crate::register::RegisterBase<$base>>::BASE + OFFSET
>                  );
>  
>                  Self(value)
> @@ -442,14 +444,14 @@ pub(crate) fn write<const SIZE: usize, T, B>(
>                  #[allow(unused_variables)]
>                  base: &B,
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  const OFFSET: usize = $name::OFFSET;
>  
>                  io.write32(
>                      self.0,
> -                    <B as crate::regs::macros::RegisterBase<$base>>::BASE + OFFSET
> +                    <B as $crate::register::RegisterBase<$base>>::BASE + OFFSET
>                  );
>              }
>  
> @@ -462,8 +464,8 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
>                  base: &B,
>                  f: F,
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  let reg = f(Self::read(io, base));
> @@ -486,7 +488,7 @@ pub(crate) fn read<const SIZE: usize, T>(
>                  io: &T,
>                  idx: usize,
>              ) -> Self where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  build_assert!(idx < Self::SIZE);
>  
> @@ -503,7 +505,7 @@ pub(crate) fn write<const SIZE: usize, T>(
>                  io: &T,
>                  idx: usize
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  build_assert!(idx < Self::SIZE);
>  
> @@ -520,7 +522,7 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
>                  idx: usize,
>                  f: F,
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  let reg = f(Self::read(io, idx));
> @@ -535,13 +537,13 @@ pub(crate) fn alter<const SIZE: usize, T, F>(
>              pub(crate) fn try_read<const SIZE: usize, T>(
>                  io: &T,
>                  idx: usize,
> -            ) -> ::kernel::error::Result<Self> where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +            ) -> $crate::error::Result<Self> where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  if idx < Self::SIZE {
>                      Ok(Self::read(io, idx))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>  
> @@ -554,13 +556,13 @@ pub(crate) fn try_write<const SIZE: usize, T>(
>                  self,
>                  io: &T,
>                  idx: usize,
> -            ) -> ::kernel::error::Result where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +            ) -> $crate::error::Result where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>              {
>                  if idx < Self::SIZE {
>                      Ok(self.write(io, idx))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>  
> @@ -574,14 +576,14 @@ pub(crate) fn try_alter<const SIZE: usize, T, F>(
>                  io: &T,
>                  idx: usize,
>                  f: F,
> -            ) -> ::kernel::error::Result where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> +            ) -> $crate::error::Result where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  if idx < Self::SIZE {
>                      Ok(Self::alter(io, idx, f))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>          }
> @@ -607,12 +609,12 @@ pub(crate) fn read<const SIZE: usize, T, B>(
>                  base: &B,
>                  idx: usize,
>              ) -> Self where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  build_assert!(idx < Self::SIZE);
>  
> -                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
> +                let offset = <B as $crate::register::RegisterBase<$base>>::BASE +
>                      Self::OFFSET + (idx * Self::STRIDE);
>                  let value = io.read32(offset);
>  
> @@ -629,12 +631,12 @@ pub(crate) fn write<const SIZE: usize, T, B>(
>                  base: &B,
>                  idx: usize
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  build_assert!(idx < Self::SIZE);
>  
> -                let offset = <B as crate::regs::macros::RegisterBase<$base>>::BASE +
> +                let offset = <B as $crate::register::RegisterBase<$base>>::BASE +
>                      Self::OFFSET + (idx * Self::STRIDE);
>  
>                  io.write32(self.0, offset);
> @@ -650,8 +652,8 @@ pub(crate) fn alter<const SIZE: usize, T, B, F>(
>                  idx: usize,
>                  f: F,
>              ) where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  let reg = f(Self::read(io, base, idx));
> @@ -668,14 +670,14 @@ pub(crate) fn try_read<const SIZE: usize, T, B>(
>                  io: &T,
>                  base: &B,
>                  idx: usize,
> -            ) -> ::kernel::error::Result<Self> where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +            ) -> $crate::error::Result<Self> where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  if idx < Self::SIZE {
>                      Ok(Self::read(io, base, idx))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>  
> @@ -690,14 +692,14 @@ pub(crate) fn try_write<const SIZE: usize, T, B>(
>                  io: &T,
>                  base: &B,
>                  idx: usize,
> -            ) -> ::kernel::error::Result where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +            ) -> $crate::error::Result where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>              {
>                  if idx < Self::SIZE {
>                      Ok(self.write(io, base, idx))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>  
> @@ -713,17 +715,19 @@ pub(crate) fn try_alter<const SIZE: usize, T, B, F>(
>                  base: &B,
>                  idx: usize,
>                  f: F,
> -            ) -> ::kernel::error::Result where
> -                T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>,
> -                B: crate::regs::macros::RegisterBase<$base>,
> +            ) -> $crate::error::Result where
> +                T: ::core::ops::Deref<Target = $crate::io::Io<SIZE>>,
> +                B: $crate::register::RegisterBase<$base>,
>                  F: ::core::ops::FnOnce(Self) -> Self,
>              {
>                  if idx < Self::SIZE {
>                      Ok(Self::alter(io, base, idx, f))
>                  } else {
> -                    Err(EINVAL)
> +                    Err($crate::error::code::EINVAL)
>                  }
>              }
>          }
>      };
>  }
> +
> +pub use register;
> -- 
> 2.34.1
> 
> 

Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>

> On 3 Sep 2025, at 18:54, Joel Fernandes <joelagnelf@nvidia.com> wrote:
> 
> Out of broad need for these macros in Rust, move them out. Several folks
> have shown interest (Nova, Tyr GPU drivers).
> 
> bitstruct - defines bitfields in Rust structs similar to C.
> register - support for defining hardware registers and accessors.
> 
> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>

Thanks a lot Joel, I will pick this up on Tyr and let you know how it went.

Expect a Tested-by tag in the coming days.

— Daniel

On 9/3/2025 5:56 PM, Daniel Almeida wrote:
> 
> 
>> On 3 Sep 2025, at 18:54, Joel Fernandes <joelagnelf@nvidia.com> wrote:
>>
>> Out of broad need for these macros in Rust, move them out. Several folks
>> have shown interest (Nova, Tyr GPU drivers).
>>
>> bitstruct - defines bitfields in Rust structs similar to C.
>> register - support for defining hardware registers and accessors.
>>
>> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
> 
> Thanks a lot Joel, I will pick this up on Tyr and let you know how it went.
> 
> Expect a Tested-by tag in the coming days.
> 
Looking forward to it, thanks!

 - Joel