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>

4 files changed, 39 insertions, 35 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/gmmu.c b/drivers/gpu/nvgpu/common/mm/gmmu.c
index ffac324c..e1942cbd 100644
--- a/drivers/gpu/nvgpu/common/mm/gmmu.c
+++ b/drivers/gpu/nvgpu/common/mm/gmmu.c
@@ -477,7 +477,7 @@ static int __nvgpu_gmmu_do_update_page_table(struct vm_gk20a *vm,
                                              struct nvgpu_gmmu_attrs *attrs)
 {
         struct gk20a *g = gk20a_from_vm(vm);
-        void *sgl;
+        struct nvgpu_sgl *sgl;
         int err = 0;
 
         if (!sgt) {
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
diff --git a/drivers/gpu/nvgpu/common/mm/page_allocator.c b/drivers/gpu/nvgpu/common/mm/page_allocator.c
index 6dc1edf7..13ccc48b 100644
--- a/drivers/gpu/nvgpu/common/mm/page_allocator.c
+++ b/drivers/gpu/nvgpu/common/mm/page_allocator.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2017, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2016-2018, 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"),
@@ -153,40 +153,41 @@ static void nvgpu_page_release_co(struct nvgpu_allocator *a,
         nvgpu_alloc_release_carveout(&va->source_allocator, co);
 }
 
-static void *nvgpu_page_alloc_sgl_next(void *sgl)
+static struct nvgpu_sgl *nvgpu_page_alloc_sgl_next(struct nvgpu_sgl *sgl)
 {
-        struct nvgpu_mem_sgl *nvgpu_sgl = sgl;
+        struct nvgpu_mem_sgl *sgl_impl = (struct nvgpu_mem_sgl *)sgl;
 
-        return nvgpu_sgl->next;
+        return (struct nvgpu_sgl *)sgl_impl->next;
 }
 
-static u64 nvgpu_page_alloc_sgl_phys(void *sgl)
+static u64 nvgpu_page_alloc_sgl_phys(struct nvgpu_sgl *sgl)
 {
-        struct nvgpu_mem_sgl *nvgpu_sgl = sgl;
+        struct nvgpu_mem_sgl *sgl_impl = (struct nvgpu_mem_sgl *)sgl;
 
-        return nvgpu_sgl->phys;
+        return sgl_impl->phys;
 }
 
-static u64 nvgpu_page_alloc_sgl_dma(void *sgl)
+static u64 nvgpu_page_alloc_sgl_dma(struct nvgpu_sgl *sgl)
 {
-        struct nvgpu_mem_sgl *nvgpu_sgl = sgl;
+        struct nvgpu_mem_sgl *sgl_impl = (struct nvgpu_mem_sgl *)sgl;
 
-        return nvgpu_sgl->dma;
+        return sgl_impl->dma;
 }
 
-static u64 nvgpu_page_alloc_sgl_length(void *sgl)
+static u64 nvgpu_page_alloc_sgl_length(struct nvgpu_sgl *sgl)
 {
-        struct nvgpu_mem_sgl *nvgpu_sgl = sgl;
+        struct nvgpu_mem_sgl *sgl_impl = (struct nvgpu_mem_sgl *)sgl;
 
-        return nvgpu_sgl->length;
+        return sgl_impl->length;
 }
 
-static u64 nvgpu_page_alloc_sgl_gpu_addr(struct gk20a *g, void *sgl,
+static u64 nvgpu_page_alloc_sgl_gpu_addr(struct gk20a *g,
+                                         struct nvgpu_sgl *sgl,
                                          struct nvgpu_gmmu_attrs *attrs)
 {
-        struct nvgpu_mem_sgl *nvgpu_sgl = sgl;
+        struct nvgpu_mem_sgl *sgl_impl = (struct nvgpu_mem_sgl *)sgl;
 
-        return nvgpu_sgl->phys;
+        return sgl_impl->phys;
 }
 
 static void nvgpu_page_alloc_sgt_free(struct gk20a *g, struct nvgpu_sgt *sgt)
@@ -229,7 +230,7 @@ static void __nvgpu_free_pages(struct nvgpu_page_allocator *a,
                                struct nvgpu_page_alloc *alloc,
                                bool free_buddy_alloc)
 {
-        struct nvgpu_mem_sgl *sgl = alloc->sgt.sgl;
+        struct nvgpu_sgl *sgl = alloc->sgt.sgl;
 
         if (free_buddy_alloc) {
                 while (sgl) {
@@ -239,7 +240,8 @@ static void __nvgpu_free_pages(struct nvgpu_page_allocator *a,
                 }
         }
 
-        nvgpu_page_alloc_sgl_proper_free(a->owner->g, sgl);
+        nvgpu_page_alloc_sgl_proper_free(a->owner->g,
+                        (struct nvgpu_mem_sgl *)sgl);
         nvgpu_kmem_cache_free(a->alloc_cache, alloc);
 }
 
@@ -389,7 +391,7 @@ static int __do_slab_alloc(struct nvgpu_page_allocator *a,
         alloc->length = slab_page->slab_size;
         alloc->base = slab_page->page_addr + (offs * slab_page->slab_size);
 
-        sgl         = alloc->sgt.sgl;
+        sgl         = (struct nvgpu_mem_sgl *)alloc->sgt.sgl;
         sgl->phys   = alloc->base;
         sgl->dma    = alloc->base;
         sgl->length = alloc->length;
@@ -430,7 +432,7 @@ static struct nvgpu_page_alloc *__nvgpu_alloc_slab(
                 goto fail;
         }
 
-        alloc->sgt.sgl = sgl;
+        alloc->sgt.sgl = (struct nvgpu_sgl *)sgl;
         err = __do_slab_alloc(a, slab, alloc);
         if (err)
                 goto fail;
@@ -582,7 +584,7 @@ static struct nvgpu_page_alloc *__do_nvgpu_alloc_pages(
                 if (prev_sgl)
                         prev_sgl->next = sgl;
                 else
-                        alloc->sgt.sgl = sgl;
+                        alloc->sgt.sgl = (struct nvgpu_sgl *)sgl;
 
                 prev_sgl = sgl;
 
@@ -595,7 +597,7 @@ static struct nvgpu_page_alloc *__do_nvgpu_alloc_pages(
         return alloc;
 
 fail_cleanup:
-        sgl = alloc->sgt.sgl;
+        sgl = (struct nvgpu_mem_sgl *)alloc->sgt.sgl;
         while (sgl) {
                 struct nvgpu_mem_sgl *next = sgl->next;
 
@@ -614,7 +616,7 @@ static struct nvgpu_page_alloc *__nvgpu_alloc_pages(
         struct nvgpu_page_allocator *a, u64 len)
 {
         struct nvgpu_page_alloc *alloc = NULL;
-        struct nvgpu_mem_sgl *sgl;
+        struct nvgpu_sgl *sgl;
         u64 pages;
         int i = 0;
 
@@ -751,7 +753,7 @@ static struct nvgpu_page_alloc *__nvgpu_alloc_pages_fixed(
 
         alloc->nr_chunks = 1;
         alloc->length = length;
-        alloc->sgt.sgl = sgl;
+        alloc->sgt.sgl = (struct nvgpu_sgl *)sgl;
 
         sgl->phys   = alloc->base;
         sgl->dma    = alloc->base;
@@ -776,7 +778,7 @@ static u64 nvgpu_page_alloc_fixed(struct nvgpu_allocator *__a,
 {
         struct nvgpu_page_allocator *a = page_allocator(__a);
         struct nvgpu_page_alloc *alloc = NULL;
-        struct nvgpu_mem_sgl *sgl;
+        struct nvgpu_sgl *sgl;
         u64 aligned_len, pages;
         int i = 0;
 
diff --git a/drivers/gpu/nvgpu/common/mm/vidmem.c b/drivers/gpu/nvgpu/common/mm/vidmem.c
index a55b3a2b..4239bd06 100644
--- a/drivers/gpu/nvgpu/common/mm/vidmem.c
+++ b/drivers/gpu/nvgpu/common/mm/vidmem.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"),
@@ -413,7 +413,7 @@ int nvgpu_vidmem_clear(struct gk20a *g, struct nvgpu_mem *mem)
         struct gk20a_fence *gk20a_fence_out = NULL;
         struct gk20a_fence *gk20a_last_fence = NULL;
         struct nvgpu_page_alloc *alloc = NULL;
-        void *sgl = NULL;
+        struct nvgpu_sgl *sgl = NULL;
         int err = 0;
 
         if (g->mm.vidmem.ce_ctx_id == (u32)~0)