[PATCH v2 07/21] gpu: nova-core: fix layout of NV_PMC_BOOT_0

Alexandre Courbot
2025-05-01T12:59:16Z

The layout of NV_PMC_BOOT_0 has two small issues:

- The "chipset" field, while useful to identify a chip, is actually an
aggregate of two distinct fields named "architecture" and
"implementation".
- The "architecture" field is split, with its MSB being at a different
location than the rest of its bits.

Redefine the register layout to match its actual definition as provided
by OpenRM and expose the fully-constructed "architecture" field through
our own "Architecture" type. The "chipset" pseudo-field is also useful
to have, so keep providing it.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
drivers/gpu/nova-core/gpu.rs | 19 ++++++++++++++++---
drivers/gpu/nova-core/regs.rs | 26 ++++++++++++++++++++++++--
2 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index f95f095baa68c9f7ffe3b1e615548aac5c2a0c6c..64c38425098c19360a7c938f2b86a55ca3c48880 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -101,9 +101,22 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// Enum representation of the GPU generation.
#[derive(fmt::Debug)]
pub(crate) enum Architecture {
- Turing,
- Ampere,
- Ada,
+ Turing = 0x16,
+ Ampere = 0x17,
+ Ada = 0x19,
+}
+
+impl TryFrom<u8> for Architecture {
+ type Error = Error;
+
+ fn try_from(value: u8) -> core::result::Result<Self, Self::Error> {
+ match value {
+ 0x16 => Ok(Self::Turing),
+ 0x17 => Ok(Self::Ampere),
+ 0x19 => Ok(Self::Ada),
+ _ => Err(ENODEV),
+ }
+ }
}

pub(crate) struct Revision {
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index 498fefb52f33bf01518f19d32287962f1fdc3224..bfb9555b203ff880c0fc373bb22e5ce6048015d4 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -4,15 +4,37 @@
// but are mapped to types.
#![allow(non_camel_case_types)]

+use kernel::error::Error;
+
#[macro_use]
mod macros;

-use crate::gpu::Chipset;
+use crate::gpu::{Architecture, Chipset};

/* PMC */

register!(NV_PMC_BOOT_0 @ 0x00000000, "Basic revision information about the GPU" {
3:0 minor_revision as u8, "Minor revision of the chip";
7:4 major_revision as u8, "Major revision of the chip";
- 28:20 chipset as u32 ?=> Chipset, "Chipset model";
+ 8:8 architecture_1 as u8, "MSB of the architecture";
+ 23:20 implementation as u8, "Implementation version of the architecture";
+ 28:24 architecture_0 as u8, "Lower bits of the architecture";
});
+
+impl NV_PMC_BOOT_0 {
+ /// Combines `architecture_0` and `architecture_1` to obtain the architecture of the chip.
+ pub(crate) fn architecture(self) -> Result<Architecture, Error> {
+ Architecture::try_from(
+ self.architecture_0() | (self.architecture_1() << Self::ARCHITECTURE_0.len()),
+ )
+ }
+
+ /// Combines `architecture` and `implementation` to obtain a code unique to the chipset.
+ pub(crate) fn chipset(self) -> Result<Chipset, Error> {
+ self.architecture()
+ .map(|arch| {
+ ((arch as u32) << Self::IMPLEMENTATION.len()) | self.implementation() as u32
+ })
+ .and_then(Chipset::try_from)
+ }
+}

--
2.49.0