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Documentation: nova: remove register abstraction task
The `register!` macro has been implemented and all nova-core code
converted to use it. Remove the corresponding task in todo.rst.
Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260325-b4-nova-register-v4-10-bdf172f0f6ca@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
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Documentation/gpu/nova/core/todo.rst
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Documentation/gpu/nova/core/todo.rst
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| Link: https://lore.kernel.org/all/cover.1750689857.git.y.j3ms.n@gmail.com/ [1]
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| Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Implement.20.60FromPrimitive.60.20trait.20.2B.20derive.20macro.20for.20nova-core/with/541971854 [2]
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Generic register abstraction [REGA]
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-----------------------------------
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Work out how register constants and structures can be automatically generated
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through generalized macros.
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Example:
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.. code-block:: rust
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register!(BOOT0, 0x0, u32, pci::Bar<SIZE>, Fields [
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MINOR_REVISION(3:0, RO),
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MAJOR_REVISION(7:4, RO),
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REVISION(7:0, RO), // Virtual register combining major and minor rev.
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])
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This could expand to something like:
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.. code-block:: rust
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const BOOT0_OFFSET: usize = 0x00000000;
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const BOOT0_MINOR_REVISION_SHIFT: u8 = 0;
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const BOOT0_MINOR_REVISION_MASK: u32 = 0x0000000f;
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const BOOT0_MAJOR_REVISION_SHIFT: u8 = 4;
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const BOOT0_MAJOR_REVISION_MASK: u32 = 0x000000f0;
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const BOOT0_REVISION_SHIFT: u8 = BOOT0_MINOR_REVISION_SHIFT;
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const BOOT0_REVISION_MASK: u32 = BOOT0_MINOR_REVISION_MASK | BOOT0_MAJOR_REVISION_MASK;
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struct Boot0(u32);
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impl Boot0 {
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#[inline]
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fn read(bar: &RevocableGuard<'_, pci::Bar<SIZE>>) -> Self {
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Self(bar.readl(BOOT0_OFFSET))
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}
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#[inline]
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fn minor_revision(&self) -> u32 {
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(self.0 & BOOT0_MINOR_REVISION_MASK) >> BOOT0_MINOR_REVISION_SHIFT
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}
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#[inline]
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fn major_revision(&self) -> u32 {
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(self.0 & BOOT0_MAJOR_REVISION_MASK) >> BOOT0_MAJOR_REVISION_SHIFT
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}
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#[inline]
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fn revision(&self) -> u32 {
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(self.0 & BOOT0_REVISION_MASK) >> BOOT0_REVISION_SHIFT
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}
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}
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Usage:
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.. code-block:: rust
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let bar = bar.try_access().ok_or(ENXIO)?;
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let boot0 = Boot0::read(&bar);
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pr_info!("Revision: {}\n", boot0.revision());
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A work-in-progress implementation currently resides in
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`drivers/gpu/nova-core/regs/macros.rs` and is used in nova-core. It would be
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nice to improve it (possibly using proc macros) and move it to the `kernel`
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crate so it can be used by other components as well.
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Features desired before this happens:
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* Make I/O optional I/O (for field values that are not registers),
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* Support other sizes than `u32`,
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* Allow visibility control for registers and individual fields,
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* Use Rust slice syntax to express fields ranges.
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| Complexity: Advanced
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| Contact: Alexandre Courbot
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Numerical operations [NUMM]
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---------------------------
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