gpu: nova-core: gsp: move Cmdq's DMA handle to a struct member

The command-queue structure has a `dma_handle` method that returns the
DMA handle to the memory segment shared with the GSP. This works, but is
not ideal for the following reasons:

- That method is effectively only ever called once, and is technically
  an accessor method since the handle doesn't change over time,
- It feels a bit out-of-place with the other methods of `Cmdq` which
  only deal with the sending or receiving of messages,
- The method has `pub(crate)` visibility, allowing other driver code to
  access this highly-sensitive handle.

Address all these issues by turning `dma_handle` into a struct member
with `pub(super)` visibility. This keeps the method space focused, and
also ensures the member is not visible outside of the modules that need
it.

Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260319-b4-cmdq-dma-handle-v1-1-57840b4a4f90@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

drivers/gpu/nova-core/gsp/cmdq.rs

@@ -30,6 +30,8 @@ use continuation::{
     SplitState, //
 };
 
+use pin_init::pin_init_scope;
+
 use crate::{
     driver::Bar0,
     gsp::{
@@ -452,6 +454,8 @@ pub(crate) struct Cmdq {
     /// Inner mutex-protected state.
     #[pin]
     inner: Mutex<CmdqInner>,
+    /// DMA handle of the command queue's shared memory region.
+    pub(super) dma_handle: DmaAddress,
 }
 
 impl Cmdq {
@@ -476,12 +480,17 @@ impl Cmdq {
 
     /// Creates a new command queue for `dev`.
     pub(crate) fn new(dev: &device::Device<device::Bound>) -> impl PinInit<Self, Error> + '_ {
-        try_pin_init!(Self {
-            inner <- new_mutex!(CmdqInner {
-                dev: dev.into(),
-                gsp_mem: DmaGspMem::new(dev)?,
-                seq: 0,
-            }),
+        pin_init_scope(move || {
+            let gsp_mem = DmaGspMem::new(dev)?;
+
+            Ok(try_pin_init!(Self {
+                dma_handle: gsp_mem.0.dma_handle(),
+                inner <- new_mutex!(CmdqInner {
+                    dev: dev.into(),
+                    gsp_mem,
+                    seq: 0,
+                }),
+            }))
         })
     }
 
@@ -567,11 +576,6 @@ impl Cmdq {
     {
         self.inner.lock().receive_msg(timeout)
     }
-
-    /// Returns the DMA handle of the command queue's shared memory region.
-    pub(crate) fn dma_handle(&self) -> DmaAddress {
-        self.inner.lock().gsp_mem.0.dma_handle()
-    }
 }
 
 /// Inner mutex protected state of [`Cmdq`].

drivers/gpu/nova-core/gsp/fw.rs

@@ -912,7 +912,7 @@ impl MessageQueueInitArguments {
     #[allow(non_snake_case)]
     fn new(cmdq: &Cmdq) -> impl Init<Self> + '_ {
         init!(MessageQueueInitArguments {
-            sharedMemPhysAddr: cmdq.dma_handle(),
+            sharedMemPhysAddr: cmdq.dma_handle,
             pageTableEntryCount: num::usize_into_u32::<{ Cmdq::NUM_PTES }>(),
             cmdQueueOffset: num::usize_as_u64(Cmdq::CMDQ_OFFSET),
             statQueueOffset: num::usize_as_u64(Cmdq::STATQ_OFFSET),