gpu: nova-core: add Chipset::name() method

There are a few cases where we need the lowercase name of a given
chipset, notably to resolve firmware files paths for dynamic loading or
to build the module information.

So far, we relied on a static `NAMES` array for the latter, and some
CString hackery for the former.

Replace both with a new `name` const method that returns the lowercase
name of a chipset instance. We can generate it using the `paste!` macro.

Using this method removes the need to create a `CString` when loading
firmware, and lets us remove a couple of utility functions that now have
no user.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250913-nova_firmware-v6-3-9007079548b0@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

Author: Gnurou

drivers/gpu/nova-core/firmware.rs

@@ -30,9 +30,7 @@ pub(crate) struct Firmware {
 
 impl Firmware {
     pub(crate) fn new(dev: &device::Device, chipset: Chipset, ver: &str) -> Result<Firmware> {
-        let mut chip_name = CString::try_from_fmt(fmt!("{chipset}"))?;
-        chip_name.make_ascii_lowercase();
-        let chip_name = &*chip_name;
+        let chip_name = chipset.name();
 
         let request = |name_| {
             CString::try_from_fmt(fmt!("nvidia/{chip_name}/gsp/{name_}-{ver}.bin"))
@@ -180,8 +178,8 @@ impl<const N: usize> ModInfoBuilder<N> {
         let mut this = Self(firmware::ModInfoBuilder::new(module_name));
         let mut i = 0;
 
-        while i < gpu::Chipset::NAMES.len() {
-            this = this.make_entry_chipset(gpu::Chipset::NAMES[i]);
+        while i < gpu::Chipset::ALL.len() {
+            this = this.make_entry_chipset(gpu::Chipset::ALL[i].name());
             i += 1;
         }
 

drivers/gpu/nova-core/gpu.rs

@@ -9,7 +9,6 @@ use crate::firmware::{Firmware, FIRMWARE_VERSION};
 use crate::gfw;
 use crate::gsp::Gsp;
 use crate::regs;
-use crate::util;
 use core::fmt;
 
 macro_rules! define_chipset {
@@ -26,13 +25,23 @@ macro_rules! define_chipset {
                 $( Chipset::$variant, )*
             ];
 
-            pub(crate) const NAMES: [&'static str; Self::ALL.len()] = [
-                $( util::const_bytes_to_str(
-                        util::to_lowercase_bytes::<{ stringify!($variant).len() }>(
-                            stringify!($variant)
-                        ).as_slice()
-                ), )*
-            ];
+            ::kernel::macros::paste!(
+            /// Returns the name of this chipset, in lowercase.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// let chipset = Chipset::GA102;
+            /// assert_eq!(chipset.name(), "ga102");
+            /// ```
+            pub(crate) const fn name(&self) -> &'static str {
+                match *self {
+                $(
+                    Chipset::$variant => stringify!([<$variant:lower>]),
+                )*
+                }
+            }
+            );
         }
 
         // TODO[FPRI]: replace with something like derive(FromPrimitive)

drivers/gpu/nova-core/util.rs

@@ -3,26 +3,6 @@
 use kernel::prelude::*;
 use kernel::time::{Delta, Instant, Monotonic};
 
-pub(crate) const fn to_lowercase_bytes<const N: usize>(s: &str) -> [u8; N] {
-    let src = s.as_bytes();
-    let mut dst = [0; N];
-    let mut i = 0;
-
-    while i < src.len() && i < N {
-        dst[i] = (src[i] as char).to_ascii_lowercase() as u8;
-        i += 1;
-    }
-
-    dst
-}
-
-pub(crate) const fn const_bytes_to_str(bytes: &[u8]) -> &str {
-    match core::str::from_utf8(bytes) {
-        Ok(string) => string,
-        Err(_) => kernel::build_error!("Bytes are not valid UTF-8."),
-    }
-}
-
 /// Wait until `cond` is true or `timeout` elapsed.
 ///
 /// When `cond` evaluates to `Some`, its return value is returned.