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, 5 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/pramin_gk20a.h b/drivers/gpu/nvgpu/gk20a/pramin_gk20a.h
index e25bda0c..a0a28088 100644
--- a/drivers/gpu/nvgpu/gk20a/pramin_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/pramin_gk20a.h
@@ -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"),
@@ -28,7 +28,9 @@ struct nvgpu_mem;
 struct nvgpu_mem_sgl;
 
 u32 gk20a_pramin_enter(struct gk20a *g, struct nvgpu_mem *mem,
-                       struct nvgpu_sgt *sgt, void *sgl, u32 w);
+                       struct nvgpu_sgt *sgt,
+                       struct nvgpu_sgl *sgl,
+                       u32 w);
 void gk20a_pramin_exit(struct gk20a *g, struct nvgpu_mem *mem,
-                       void *sgl);
+                       struct nvgpu_sgl *sgl);
 #endif