[RFC 2/3] drm: nova: Add GETPARAM parameter to read the GPU chipset

[Alistair Popple <apopple@nvidia.com>]

One of the first things a user needs to know about a GPU is its chipset,
so add an ioctl to return that.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 drivers/gpu/drm/nova/file.rs     |  5 +++++
 drivers/gpu/nova-core/auxdata.rs | 10 +++++++++-
 drivers/gpu/nova-core/driver.rs  |  2 +-
 drivers/gpu/nova-core/gpu.rs     | 10 +++++-----
 include/uapi/drm/nova_drm.h      |  7 +++++++
 5 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/nova/file.rs b/drivers/gpu/drm/nova/file.rs
index 298c02bacb4b..8147dfb366d8 100644
--- a/drivers/gpu/drm/nova/file.rs
+++ b/drivers/gpu/drm/nova/file.rs
@@ -16,6 +16,9 @@
     uapi,
 };
 
+use kernel::types::ForLt;
+use nova_core::auxdata::AuxData;
+
 pub(crate) struct File;
 
 impl drm::file::DriverFile for File {
@@ -36,9 +39,11 @@ pub(crate) fn get_param(
     ) -> Result<u32> {
         let adev: &auxiliary::Device<Bound> = dev.as_ref();
         let pdev: &pci::Device<Bound> = adev.parent().try_into()?;
+        let data = adev.registration_data::<ForLt!(AuxData<'_>)>()?;
 
         let value = match getparam.param as u32 {
             uapi::NOVA_GETPARAM_VRAM_BAR_SIZE => pdev.resource_len(1)?,
+            uapi::NOVA_GETPARAM_GPU_CHIPSET => data.chipset() as u64,
             _ => return Err(EINVAL),
         };
 
diff --git a/drivers/gpu/nova-core/auxdata.rs b/drivers/gpu/nova-core/auxdata.rs
index 266b5ce4ee89..cd8a3511293b 100644
--- a/drivers/gpu/nova-core/auxdata.rs
+++ b/drivers/gpu/nova-core/auxdata.rs
@@ -3,10 +3,18 @@
 //! Nova-core auxbus data. Contains all the methods used by the auxbus drivers
 //! to interact with nova-core.
 
+use crate::gpu::Chipset;
 use crate::gpu::Gpu;
 
 /// Auxiliary bus registration data. Used by the auxbus drivers to call methods on
 /// the GPU.
 pub struct AuxData<'bound> {
-    pub(crate) _gpu: &'bound Gpu<'bound>,
+    pub(crate) gpu: &'bound Gpu<'bound>,
+}
+
+impl AuxData<'_> {
+    /// Returns the chipset of this GPU.
+    pub fn chipset(&self) -> Chipset {
+        self.gpu.spec.chipset
+    }
 }
diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index ad232ca11833..193e87ac624e 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -112,7 +112,7 @@ fn probe<'bound>(
                             // (`try_pin_init!()` initializes fields in declaration order), lives at
                             // a pinned stable address, and is dropped after `_reg` (struct field
                             // drop order).
-                            _gpu: &*core::ptr::from_ref(&this.as_ref().gpu),
+                            gpu: &*core::ptr::from_ref(&this.as_ref().gpu),
                         },
                     )?
                 },
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 43c3f4f8df71..d4a71a1be6f1 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -38,7 +38,7 @@ macro_rules! define_chipset {
     {
         /// Enum representation of the GPU chipset.
         #[derive(fmt::Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
-        pub(crate) enum Chipset {
+        pub enum Chipset {
             $($variant = $value),*,
         }
 
@@ -114,7 +114,7 @@ fn try_from(value: u32) -> Result<Self, Self::Error> {
 });
 
 impl Chipset {
-    pub(crate) const fn arch(self) -> Architecture {
+    pub const fn arch(self) -> Architecture {
         match self {
             Self::TU102 | Self::TU104 | Self::TU106 | Self::TU117 | Self::TU116 => {
                 Architecture::Turing
@@ -172,7 +172,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 bounded_enum! {
     /// Enum representation of the GPU generation.
     #[derive(fmt::Debug, Copy, Clone)]
-    pub(crate) enum Architecture with TryFrom<Bounded<u32, 6>> {
+    pub enum Architecture with TryFrom<Bounded<u32, 6>> {
         Turing = 0x16,
         Ampere = 0x17,
         Hopper = 0x18,
@@ -206,7 +206,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 /// Structure holding a basic description of the GPU: `Chipset` and `Revision`.
 #[derive(Clone, Copy)]
 pub(crate) struct Spec {
-    chipset: Chipset,
+    pub(crate) chipset: Chipset,
     revision: Revision,
 }
 
@@ -286,7 +286,7 @@ struct GspResources<'gpu> {
 /// Structure holding the resources required to operate the GPU.
 #[pin_data]
 pub(crate) struct Gpu<'gpu> {
-    spec: Spec,
+    pub(crate) spec: Spec,
     /// Static GPU information as provided by the GSP.
     gsp_static_info: GetGspStaticInfoReply,
     /// GSP and its resources.
diff --git a/include/uapi/drm/nova_drm.h b/include/uapi/drm/nova_drm.h
index 3ca90ed9d2bb..63440f5dca9b 100644
--- a/include/uapi/drm/nova_drm.h
+++ b/include/uapi/drm/nova_drm.h
@@ -25,6 +25,13 @@ extern "C" {
  */
 #define NOVA_GETPARAM_VRAM_BAR_SIZE	0x1
 
+/*
+ * NOVA_GETPARAM_GPU_CHIPSET
+ *
+ * Query the GPU chipset architecture/implementation.
+ */
+#define NOVA_GETPARAM_GPU_CHIPSET	0x2
+
 /**
  * struct drm_nova_getparam - query GPU and driver metadata
  */
-- 
2.54.0