[PATCH v2 00/16] rust: io: support register projections and remove relative registers

[Gary Guo <gary@garyguo.net>]

Currently registers work for all untyped I/O regions, which is not ideal.
It allows registers defined for device A to work for another device B and
there is no safeguarding at all.

Change this by requiring a base type for registers. `register!` can still
define registers on untyped `Region`s, although users would need to do so
explicitly and supply a concrete type.

This change makes it possible to use projection for relative registers;
relative registers can be implemented by defining new types for the I/O
subregions and just define registers for these subregion types like normal
registers.

This actually results in more ergnomic code for users of relative registers
(currently only nova-core), because non-array registers can be written to
with

    #[...]
    struct Subregion(...);

    register! {
        base: MyBase;
        SUBREGION: Subregion @ ...;
    }

    register! {
        base: Subregion;
        REG(u32) @ .. { .. }
    }

    let subregion = io_project!(bar, build: SUBREGION);
    subregion.read(REG)
    subregion.write_reg(reg)

instead of

    struct SubregionType;
    struct Subregion;
    impl RegisterBase<SubregionType> for Subregion {
        const BASE: usize = ...;
    }

    register! {
        REG(u32) @ Subregion + .. { .. }
    }

    bar.read(REG::of::<Subregion>())
    bar.write(WithBase::of::<Subregion>(), reg)

This also allows a lot more code sharing between I/O projection and
`register!` macro.

Signed-off-by: Gary Guo <gary@garyguo.net>
---
Changes in v2:
- Extract type conversion from `register!` to `Io`
- Redesign the API to be centered around regsiter projections.
  * Support register projections in `io_project!`
  * Support adding register definition without defining bitfield
  * Subregions is thus unified with other registers.
- Store projected subregions in `Falcon` for nova.
- Link to v1: https://patch.msgid.link/20260721-typed_register-v1-0-452d72b60262@garyguo.net

---
Gary Guo (16):
      rust: io: add static `cast()` method for views
      rust: io: add `IoRepr` trait
      rust: io: support register projections
      rust: io: register: handle one register at a time
      rust: io: register extract offset computation to helper rules
      rust: io: register: allow explicit base type specification
      gpu: nova-core: specify base type for registers
      drm/tyr: specify base type for registers
      samples: rust: pci: specify base type for registers
      rust: io: register: make register have a typed base
      rust: io: register: support fixed offset register without bitfield
      gpu: nova-core: use projection for PFALCON and PFALCON2 registers
      gpu: nova-core: convert hshub0 from relative register to projection
      rust: io: register: remove relative registers
      rust: io: register: remove `Register` trait and cleanup macro
      rust: io: register: unify handling of register with/without bitfields

 drivers/gpu/drm/tyr/driver.rs                      |   1 +
 drivers/gpu/drm/tyr/regs.rs                        |  43 +-
 drivers/gpu/nova-core/driver.rs                    |   1 +
 drivers/gpu/nova-core/falcon.rs                    | 157 ++---
 drivers/gpu/nova-core/falcon/fsp.rs                |  63 +-
 drivers/gpu/nova-core/falcon/gsp.rs                |  51 +-
 drivers/gpu/nova-core/falcon/hal/ga102.rs          |  62 +-
 drivers/gpu/nova-core/falcon/hal/tu102.rs          |   9 +-
 drivers/gpu/nova-core/falcon/sec2.rs               |  37 +-
 drivers/gpu/nova-core/fb/hal/gb100.rs              |  59 +-
 drivers/gpu/nova-core/fb/regs.rs                   |  29 +-
 drivers/gpu/nova-core/firmware/fwsec/bootloader.rs |  18 +-
 drivers/gpu/nova-core/gsp/hal/tu102.rs             |   7 +-
 drivers/gpu/nova-core/gsp/regs.rs                  |   9 +-
 drivers/gpu/nova-core/regs.rs                      | 114 +--
 drivers/gpu/nova-core/vbios.rs                     |  11 +-
 rust/kernel/bitfield.rs                            |   5 +
 rust/kernel/io.rs                                  | 295 ++++++--
 rust/kernel/io/register.rs                         | 774 ++++++---------------
 samples/rust/rust_driver_pci.rs                    |   4 +
 20 files changed, 828 insertions(+), 921 deletions(-)
---
base-commit: 1701fda2f58e345c050f4309971bdc07cd6146ba
change-id: 20260721-typed_register-176eab3abee7

Best regards,
--  
Gary Guo <gary@garyguo.net>