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>

3 files changed, 11 insertions, 8 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.h b/drivers/gpu/nvgpu/gk20a/gk20a.h
index ac3364b0..5de2b439 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.h
@@ -823,9 +823,10 @@ struct gpu_ops {
                                 size_t size);
         struct {
                 u32 (*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 (*exit)(struct gk20a *g, struct nvgpu_mem *mem,
-                        void *sgl);
+                        struct nvgpu_sgl *sgl);
                 u32 (*data032_r)(u32 i);
         } pramin;
         struct {
diff --git a/drivers/gpu/nvgpu/gk20a/pramin_gk20a.c b/drivers/gpu/nvgpu/gk20a/pramin_gk20a.c
index 05d0473e..bb8831e0 100644
--- a/drivers/gpu/nvgpu/gk20a/pramin_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/pramin_gk20a.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"),
@@ -32,7 +32,7 @@
 
 /* WARNING: returns pramin_window_lock taken, complement with pramin_exit() */
 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)
 {
         u64 bufbase = nvgpu_sgt_get_phys(sgt, sgl);
         u64 addr = bufbase + w * sizeof(u32);
@@ -64,7 +64,7 @@ u32 gk20a_pramin_enter(struct gk20a *g, struct nvgpu_mem *mem,
 }
 
 void gk20a_pramin_exit(struct gk20a *g, struct nvgpu_mem *mem,
-                       void *sgl)
+                       struct nvgpu_sgl *sgl)
 {
         gk20a_dbg(gpu_dbg_mem, "end for %p,%p", mem, sgl);
 
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