[PATCH v8 09/13] gpu: nova-core: add Falcon HAL method load_method()

[Timur Tabi <ttabi@nvidia.com>]

Some GPUs do not support using DMA to transfer code/data from system
memory to Falcon memory, and instead must use programmed I/O (PIO).
Add a function to the Falcon HAL to indicate whether a given GPU's
Falcons support DMA for this purpose.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
---
 drivers/gpu/nova-core/falcon/hal.rs       | 14 ++++++++++++++
 drivers/gpu/nova-core/falcon/hal/ga102.rs |  5 +++++
 drivers/gpu/nova-core/falcon/hal/tu102.rs |  5 +++++
 3 files changed, 24 insertions(+)

diff --git a/drivers/gpu/nova-core/falcon/hal.rs b/drivers/gpu/nova-core/falcon/hal.rs
index c886ba03d1f6..fe6de900e8b0 100644
--- a/drivers/gpu/nova-core/falcon/hal.rs
+++ b/drivers/gpu/nova-core/falcon/hal.rs
@@ -15,6 +15,16 @@
 mod ga102;
 mod tu102;
 
+/// Method used to load data into falcon memory. Some GPU architectures need
+/// PIO and others can use DMA.
+#[expect(unused)]
+pub(crate) enum LoadMethod {
+    /// Programmed I/O
+    Pio,
+    /// Direct Memory Access
+    Dma,
+}
+
 /// Hardware Abstraction Layer for Falcon cores.
 ///
 /// Implements chipset-specific low-level operations. The trait is generic against [`FalconEngine`]
@@ -48,6 +58,10 @@ fn signature_reg_fuse_version(
 
     /// Reset the falcon engine.
     fn reset_eng(&self, bar: &Bar0) -> Result;
+
+    /// returns the method needed to load data into Falcon memory
+    #[expect(unused)]
+    fn load_method(&self) -> LoadMethod;
 }
 
 /// Returns a boxed falcon HAL adequate for `chipset`.
diff --git a/drivers/gpu/nova-core/falcon/hal/ga102.rs b/drivers/gpu/nova-core/falcon/hal/ga102.rs
index 39863813a2bf..8f62df10da0a 100644
--- a/drivers/gpu/nova-core/falcon/hal/ga102.rs
+++ b/drivers/gpu/nova-core/falcon/hal/ga102.rs
@@ -12,6 +12,7 @@
 use crate::{
     driver::Bar0,
     falcon::{
+        hal::LoadMethod,
         Falcon,
         FalconBromParams,
         FalconEngine,
@@ -151,4 +152,8 @@ fn reset_eng(&self, bar: &Bar0) -> Result {
 
         Ok(())
     }
+
+    fn load_method(&self) -> LoadMethod {
+        LoadMethod::Dma
+    }
 }
diff --git a/drivers/gpu/nova-core/falcon/hal/tu102.rs b/drivers/gpu/nova-core/falcon/hal/tu102.rs
index 23fbf6110572..7de6f24cc0a0 100644
--- a/drivers/gpu/nova-core/falcon/hal/tu102.rs
+++ b/drivers/gpu/nova-core/falcon/hal/tu102.rs
@@ -11,6 +11,7 @@
 use crate::{
     driver::Bar0,
     falcon::{
+        hal::LoadMethod,
         Falcon,
         FalconBromParams,
         FalconEngine, //
@@ -69,4 +70,8 @@ fn reset_eng(&self, bar: &Bar0) -> Result {
 
         Ok(())
     }
+
+    fn load_method(&self) -> LoadMethod {
+        LoadMethod::Pio
+    }
 }
-- 
2.52.0