gpu: nvgpu: introduce explicit nvgpu_sgl type

The operations in struct nvgpu_sgt_ops have a scatter-gather list (sgl)
argument which is a void pointer. Change the type signatures to take
struct nvgpu_sgl * which is an opaque marker type that makes it more
difficult to pass around wrong arguments, as anything goes for void *.
Explicit types add also self-documentation to the code.

For some added safety, some explicit type casts are now required in
implementors of the nvgpu_sgt_ops interface when converting between the
general nvgpu_sgl type and implementation-specific types.  This is not
purely a bad thing because the casts explain clearly where type
conversions are happening.

Jira NVGPU-30
Jira NVGPU-52
Jira NVGPU-305

Change-Id: Ic64eed6d2d39ca5786e62b172ddb7133af16817a
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1643555
GVS: Gerrit_Virtual_Submit
Reviewed-by: Vijayakumar Subbu <vsubbu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c b/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
index 206b83e1..7406c4d7 100644
--- a/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
+++ b/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
@@ -499,27 +499,28 @@ int __nvgpu_mem_create_from_phys(struct gk20a *g, struct nvgpu_mem *dest,
 }
 #endif
 
-static void *nvgpu_mem_linux_sgl_next(void *sgl)
+static struct nvgpu_sgl *nvgpu_mem_linux_sgl_next(struct nvgpu_sgl *sgl)
 {
-        return sg_next((struct scatterlist *)sgl);
+        return (struct nvgpu_sgl *)sg_next((struct scatterlist *)sgl);
 }
 
-static u64 nvgpu_mem_linux_sgl_phys(void *sgl)
+static u64 nvgpu_mem_linux_sgl_phys(struct nvgpu_sgl *sgl)
 {
         return (u64)sg_phys((struct scatterlist *)sgl);
 }
 
-static u64 nvgpu_mem_linux_sgl_dma(void *sgl)
+static u64 nvgpu_mem_linux_sgl_dma(struct nvgpu_sgl *sgl)
 {
         return (u64)sg_dma_address((struct scatterlist *)sgl);
 }
 
-static u64 nvgpu_mem_linux_sgl_length(void *sgl)
+static u64 nvgpu_mem_linux_sgl_length(struct nvgpu_sgl *sgl)
 {
         return (u64)((struct scatterlist *)sgl)->length;
 }
 
-static u64 nvgpu_mem_linux_sgl_gpu_addr(struct gk20a *g, void *sgl,
+static u64 nvgpu_mem_linux_sgl_gpu_addr(struct gk20a *g,
+                                        struct nvgpu_sgl *sgl,
                                         struct nvgpu_gmmu_attrs *attrs)
 {
         if (sg_dma_address((struct scatterlist *)sgl) == 0)
@@ -587,7 +588,7 @@ struct nvgpu_sgt *nvgpu_linux_sgt_create(struct gk20a *g, struct sg_table *sgt)
 
         nvgpu_log(g, gpu_dbg_sgl, "Making Linux SGL!");
 
-        nvgpu_sgt->sgl = sgt->sgl;
+        nvgpu_sgt->sgl = (struct nvgpu_sgl *)linux_sgl;
         nvgpu_sgt->ops = &nvgpu_linux_sgt_ops;
 
         return nvgpu_sgt;