drm/amdgpu: add basics for SDMA page queue support

Just the common helper and a new ring in the SDMA instance.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c

@@ -34,11 +34,9 @@ struct amdgpu_sdma_instance * amdgpu_get_sdma_instance(struct amdgpu_ring *ring)
 	int i;
 
 	for (i = 0; i < adev->sdma.num_instances; i++)
-		if (&adev->sdma.instance[i].ring == ring)
-			break;
+		if (ring == &adev->sdma.instance[i].ring ||
+		    ring == &adev->sdma.instance[i].page)
+			return &adev->sdma.instance[i];
 
-	if (i < AMDGPU_MAX_SDMA_INSTANCES)
-		return &adev->sdma.instance[i];
-	else
-		return NULL;
+	return NULL;
 }

drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.h

@@ -41,6 +41,7 @@ struct amdgpu_sdma_instance {
 	uint32_t		feature_version;
 
 	struct amdgpu_ring	ring;
+	struct amdgpu_ring	page;
 	bool			burst_nop;
 };