[PATCH v5 0/3] rust: add `bitfield!` macro

[Alexandre Courbot <acourbot@nvidia.com>]

This is the continuation of the `bitfield!` macro which started
alongside the `register!` one before being temporarily integrated into
it [1].

This series extracts `bitfield!` from `register!`, adds unit tests for
the new macro, and replaces the `register!` macro rules with the
extracted version.

I have removed the `nova-core` patches, because the Blackwell support
that has been added this cycle (and thus not visible from `rust-next`)
introduces more uses of the Nova-local `bitfield!` macro that this
series intended to remove. If these new uses are not updated, then
`nova-core` won't build, thus to avoid conflicts and/or build breakages
I think it is preferable to merge them during the next cycle.

This version is based on `rust-next`, with [2] applied.

A tree with this branch and its dependencies is available at [3].

[1] https://lore.kernel.org/all/20260120-register-v1-0-723a1743b557@nvidia.com/
[2] https://lore.kernel.org/all/20260417031531.315281-1-ynorov@nvidia.com/
[3] https://github.com/Gnurou/linux/tree/b4/bitfield

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
Changes in v5:
- Squash the fixup patches into the one extracting the `bitfield!` macro.
- Remove the `nova-core` patches to avoid a conflict/build breakage on
  -rc1.
- Improve the unit tests per Yury's feedback:
  - Use a consistent test axis where each test focuses on a single thing.
  - Rename members to generic name including range for readability.
  - Add test exercising `try_with`.
  - Add test checking that unallocated bits are left untouched.
- Link to v4: https://patch.msgid.link/20260527-bitfield-v4-0-e8821d4efbde@nvidia.com

Changes in v4:
- Inline private bitfield accessor methods.
- Fully qualify types in `bitfield!` macro.
- Rename `RUST_KERNEL_BITFIELD_KUNIT_TEST` to `RUST_BITFIELD_KUNIT_TEST`.
- Link to v3: https://patch.msgid.link/20260501-bitfield-v3-0-aa1076c3337d@nvidia.com

Changes in v3:
- Split patch 1 into the addition of the `bitfield!` macro and its use
  in the `io` module.
- Mention reserved field names in `bitfield!`'s doccomment.
- Properly order fields in the KUnit test.
- Add a Kconfig option for building the KUnit tests.
- Document behavior on non-covered bits.
- Document support for signed fields and storage types (TL;DR: not
  supported).
- Move `nova-core`'s `bitfield` module deletion into its own patch.
- Link to v2: https://patch.msgid.link/20260409-bitfield-v2-0-23ac400071cb@nvidia.com

---
Alexandre Courbot (2):
      rust: extract `bitfield!` macro from `register!`
      rust: io: use the `bitfield!` macro in `register!`

Joel Fernandes (1):
      rust: bitfield: Add KUnit tests for bitfield

 MAINTAINERS                |   7 +
 rust/kernel/Kconfig.test   |  10 +
 rust/kernel/bitfield.rs    | 862 +++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/io/register.rs | 246 +------------
 rust/kernel/lib.rs         |   1 +
 5 files changed, 882 insertions(+), 244 deletions(-)
---
base-commit: 72d33b8bfeacbfdccf2cda4650e8e002def036f8
change-id: 20260408-bitfield-6e18254f4fdc
prerequisite-message-id: 20260417031531.315281-1-ynorov@nvidia.com
prerequisite-patch-id: 403e34bb92b42d3f31ed972e11896d18902585e3
prerequisite-patch-id: 42ae775aa6762a9e28ff31c5f69a0b65a7b40dcc
prerequisite-patch-id: 19b3e535962348f7627ede57ea829b34abda08c7

Best regards,
--  
Alexandre Courbot <acourbot@nvidia.com>