gpu: nvgpu: Add common vaddr translate function

Add a function to do address translation for IOMMU capable GPUs.
When an iGPU is behind and IOMMU it can pick whether to use that
IOMMU for translation by adding a bit to physical addresses. This
function takes care of that.

However, this required an abstracted nvgpu_iommuable() API to
check whether a GPU is behind an IOMMU. This patch adds that API
for Linux.

JIRA NVGPU-68

Change-Id: I489d14475167c019c294407372395df78c8b5feb
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1542965
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Sourab Gupta <sourabg@nvidia.com>
Reviewed-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-by: Vijayakumar Subbu <vsubbu@nvidia.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/dma.h b/drivers/gpu/nvgpu/include/nvgpu/dma.h
index 50681f8d..c0397b58 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/dma.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/dma.h
@@ -51,6 +51,20 @@ struct nvgpu_mem;
 #define NVGPU_DMA_READ_ONLY             (1 << 2)
 
 /**
+ * nvgpu_iommuable - Check if GPU is behind IOMMU
+ *
+ * @g - The GPU.
+ *
+ * Returns true if the passed GPU is behind an IOMMU; false otherwise. If the
+ * GPU is iommuable then the DMA address in nvgpu_mem_sgl is valid.
+ *
+ * Note that even if a GPU is behind an IOMMU that does not necessarily mean the
+ * GPU _must_ use DMA addresses. GPUs may still use physical addresses if it
+ * makes sense.
+ */
+bool nvgpu_iommuable(struct gk20a *g);
+
+/**
  * nvgpu_dma_alloc - Allocate DMA memory
  *
  * @g    - The GPU.