gpu: nvgpu: Add __nvgpu_mem_create_from_pages()

Add a function to create a nvgpu_mem from a list of arbitrary pages.
This API is useful for pages not necessarily allocated by the Linux
page allocator. It is useful for making nvgpu_mems that represent
carveouts or other things like that.

JIRA NVGPU-12
JIRA NVGPU-30

Change-Id: Ibcb6432f077a6b0ecf9d183248e47a1f9ecb3ddd
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1464080
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>

2 files changed, 46 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/dma.c b/drivers/gpu/nvgpu/common/linux/dma.c
index abcf36f1..eb2d0ac4 100644
--- a/drivers/gpu/nvgpu/common/linux/dma.c
+++ b/drivers/gpu/nvgpu/common/linux/dma.c
@@ -335,6 +335,7 @@ static void nvgpu_dma_free_sys(struct gk20a *g, struct nvgpu_mem *mem)
         struct device *d = dev_from_gk20a(g);
 
         if (!(mem->mem_flags & NVGPU_MEM_FLAG_SHADOW_COPY) &&
+            !(mem->mem_flags & __NVGPU_MEM_FLAG_NO_DMA) &&
             (mem->cpu_va || mem->priv.pages)) {
                 if (mem->priv.flags) {
                         DEFINE_DMA_ATTRS(dma_attrs);
@@ -358,6 +359,13 @@ static void nvgpu_dma_free_sys(struct gk20a *g, struct nvgpu_mem *mem)
                 mem->priv.pages = NULL;
         }
 
+        /*
+         * When this flag is set we expect that pages is still populated but not
+         * by the DMA API.
+         */
+        if (mem->mem_flags & __NVGPU_MEM_FLAG_NO_DMA)
+                nvgpu_kfree(g, mem->priv.pages);
+
         if (mem->priv.sgt)
                 nvgpu_free_sgtable(g, &mem->priv.sgt);
 
diff --git a/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c b/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
index b46dbb6b..58488067 100644
--- a/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
+++ b/drivers/gpu/nvgpu/common/linux/nvgpu_mem.c
@@ -297,3 +297,41 @@ int nvgpu_mem_create_from_mem(struct gk20a *g,
 
         return ret;
 }
+
+int __nvgpu_mem_create_from_pages(struct gk20a *g, struct nvgpu_mem *dest,
+                                  struct page **pages, int nr_pages)
+{
+        struct sg_table *sgt;
+        struct page **our_pages =
+                nvgpu_kmalloc(g, sizeof(struct page *) * nr_pages);
+
+        if (!our_pages)
+                return -ENOMEM;
+
+        memcpy(our_pages, pages, sizeof(struct page *) * nr_pages);
+
+        if (nvgpu_get_sgtable_from_pages(g, &sgt, pages, 0,
+                                         nr_pages * PAGE_SIZE)) {
+                nvgpu_kfree(g, our_pages);
+                return -ENOMEM;
+        }
+
+        /*
+         * If we are making an SGT from physical pages we can be reasonably
+         * certain that this should bypass the SMMU - thus we set the DMA (aka
+         * IOVA) address to 0. This tells the GMMU mapping code to not make a
+         * mapping directed to the SMMU.
+         */
+        sg_dma_address(sgt->sgl) = 0;
+
+        dest->mem_flags  = __NVGPU_MEM_FLAG_NO_DMA;
+        dest->aperture   = APERTURE_SYSMEM;
+        dest->skip_wmb   = 0;
+        dest->size       = PAGE_SIZE * nr_pages;
+
+        dest->priv.flags = 0;
+        dest->priv.pages = our_pages;
+        dest->priv.sgt   = sgt;
+
+        return 0;
+}