[PATCH v4 5/7] drm: nova: Add usable VRAM size to GPU info ioctl

[Alistair Popple <apopple@nvidia.com>]

Add a parameter to the GPU info ioctl to return the total usable
framebuffer size. The usable framebuffer excludes GSP carveouts and
other protected regions so may differ in size from BAR size and total
physical VRAM.

Signed-off-by: Alistair Popple <apopple@nvidia.com>

---

Changes since v3:

 - Partially new for v4 - previously this used GETPARAM
---
 drivers/gpu/drm/nova/file.rs          | 1 +
 drivers/gpu/nova-core/api.rs          | 5 +++++
 drivers/gpu/nova-core/gpu.rs          | 6 ++----
 drivers/gpu/nova-core/gsp/commands.rs | 8 ++++++++
 include/uapi/drm/nova_drm.h           | 6 ++++++
 5 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nova/file.rs b/drivers/gpu/drm/nova/file.rs
index 97688edd07af..cbe45d022ac6 100644
--- a/drivers/gpu/drm/nova/file.rs
+++ b/drivers/gpu/drm/nova/file.rs
@@ -92,6 +92,7 @@ pub(crate) fn gpu_info(
 
         gpu_info.size = size_of::<uapi::drm_nova_gpu_info>() as u64;
         gpu_info.chipid = reg_data.api.chipset() as u32;
+        gpu_info.vram_size = reg_data.api.vram_size();
 
         Ok(0)
     }
diff --git a/drivers/gpu/nova-core/api.rs b/drivers/gpu/nova-core/api.rs
index 09da0b4e9103..f025df90dc5d 100644
--- a/drivers/gpu/nova-core/api.rs
+++ b/drivers/gpu/nova-core/api.rs
@@ -33,4 +33,9 @@ pub fn of(adev: &auxiliary::Device<Bound>) -> Result<Pin<&NovaCoreApi<'_>>> {
     pub fn chipset(&self) -> Chipset {
         self.gpu.spec.chipset
     }
+
+    /// Returns the total usable VRAM size of this GPU in bytes.
+    pub fn vram_size(&self) -> u64 {
+        self.gpu.gsp_static_info.vram_size()
+    }
 }
diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 34a496ec3b38..7a2037105d29 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -283,7 +283,7 @@ struct GspResources<'gpu> {
 pub(crate) struct Gpu<'gpu> {
     pub(crate) spec: Spec,
     /// Static GPU information as provided by the GSP.
-    gsp_static_info: GetGspStaticInfoReply,
+    pub(crate) gsp_static_info: GetGspStaticInfoReply,
     /// GSP and its resources.
     #[pin]
     gsp_resources: GspResources<'gpu>,
@@ -400,9 +400,7 @@ pub(crate) fn new(
                     dev_dbg!(
                         dev,
                         "Total usable VRAM: {} MiB\n",
-                        info.usable_fb_regions.iter().fold(0u64, |res, region| res
-                            .saturating_add(region.end - region.start))
-                            / u64::SZ_1M
+                        info.vram_size() / u64::SZ_1M
                     );
                 }
 
diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index 08380de39048..49ff3f5edcec 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -252,6 +252,14 @@ pub(crate) fn gpu_name(&self) -> core::result::Result<&str, GpuNameError> {
             .to_str()
             .map_err(GpuNameError::InvalidUtf8)
     }
+
+    /// Returns the total usable VRAM size in bytes, i.e. the summed lengths of all usable FB
+    /// regions.
+    pub(crate) fn vram_size(&self) -> u64 {
+        self.usable_fb_regions.iter().fold(0, |size, region| {
+            size.saturating_add(region.end - region.start)
+        })
+    }
 }
 
 pub(crate) use fw::commands::PowerStateLevel;
diff --git a/include/uapi/drm/nova_drm.h b/include/uapi/drm/nova_drm.h
index 2604e4d2698b..e315556dac26 100644
--- a/include/uapi/drm/nova_drm.h
+++ b/include/uapi/drm/nova_drm.h
@@ -140,6 +140,12 @@ struct drm_nova_gpu_info {
 	 * @pad: 32 bit padding, must be 0.
 	 */
 	__u32 pad;
+
+	/**
+	 * @vram_size: Amount of usable FB, excluding GSP carveouts and protected
+	 * regions.
+	 */
+	__u64 vram_size;
 };
 
 #define DRM_NOVA_GETPARAM		0x00
-- 
2.54.0