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, 9 insertions, 7 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c b/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
index 73b6b2a7..f7c51f42 100644
--- a/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
+++ b/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2017-2018, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -28,27 +28,29 @@
 
 #include "gk20a/gk20a.h"
 
-void *nvgpu_sgt_get_next(struct nvgpu_sgt *sgt, void *sgl)
+struct nvgpu_sgl *nvgpu_sgt_get_next(struct nvgpu_sgt *sgt,
+                                     struct nvgpu_sgl *sgl)
 {
         return sgt->ops->sgl_next(sgl);
 }
 
-u64 nvgpu_sgt_get_phys(struct nvgpu_sgt *sgt, void *sgl)
+u64 nvgpu_sgt_get_phys(struct nvgpu_sgt *sgt, struct nvgpu_sgl *sgl)
 {
         return sgt->ops->sgl_phys(sgl);
 }
 
-u64 nvgpu_sgt_get_dma(struct nvgpu_sgt *sgt, void *sgl)
+u64 nvgpu_sgt_get_dma(struct nvgpu_sgt *sgt, struct nvgpu_sgl *sgl)
 {
         return sgt->ops->sgl_dma(sgl);
 }
 
-u64 nvgpu_sgt_get_length(struct nvgpu_sgt *sgt, void *sgl)
+u64 nvgpu_sgt_get_length(struct nvgpu_sgt *sgt, struct nvgpu_sgl *sgl)
 {
         return sgt->ops->sgl_length(sgl);
 }
 
-u64 nvgpu_sgt_get_gpu_addr(struct gk20a *g, struct nvgpu_sgt *sgt, void *sgl,
+u64 nvgpu_sgt_get_gpu_addr(struct gk20a *g, struct nvgpu_sgt *sgt,
+                           struct nvgpu_sgl *sgl,
                            struct nvgpu_gmmu_attrs *attrs)
 {
         return sgt->ops->sgl_gpu_addr(g, sgl, attrs);
@@ -88,7 +90,7 @@ u64 nvgpu_mem_iommu_translate(struct gk20a *g, u64 phys)
 u64 nvgpu_sgt_alignment(struct gk20a *g, struct nvgpu_sgt *sgt)
 {
         u64 align = 0, chunk_align = 0;
-        void *sgl;
+        struct nvgpu_sgl *sgl;
 
         /*
          * If this SGT is iommuable and we want to use the IOMMU address then