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, 41 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/linux/nvgpu_mem.h b/drivers/gpu/nvgpu/include/nvgpu/linux/nvgpu_mem.h
index 8b1e646e..9c52811e 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/linux/nvgpu_mem.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/linux/nvgpu_mem.h
@@ -20,10 +20,41 @@
 struct page;
 struct sg_table;
 
+struct gk20a;
+struct nvgpu_mem;
+
 struct nvgpu_mem_priv {
         struct page **pages;
         struct sg_table *sgt;
         unsigned long flags;
 };
 
+/**
+ * __nvgpu_mem_create_from_pages - Create an nvgpu_mem from physical pages.
+ *
+ * @g        - The GPU.
+ * @dest     - nvgpu_mem to initialize.
+ * @pages    - A list of page pointers.
+ * @nr_pages - The number of pages in @pages.
+ *
+ * Create a new nvgpu_mem struct from a pre-existing list of physical pages. The
+ * pages need not be contiguous (the underlying scatter gather list will help
+ * with that). However, note, this API will explicitly make it so that the GMMU
+ * mapping code bypasses SMMU access for the passed pages. This allows one to
+ * make mem_descs that describe MMIO regions or other non-DRAM things.
+ *
+ * This only works for SYSMEM (or other things like SYSMEM - basically just not
+ * VIDMEM). Also, this API is only available for Linux as it heavily depends on
+ * the notion of struct %page.
+ *
+ * The resulting nvgpu_mem should be released with the nvgpu_dma_free() or the
+ * nvgpu_dma_unmap_free() function depending on whether or not the resulting
+ * nvgpu_mem has been mapped. The underlying pages themselves must be cleaned up
+ * by the caller of this API.
+ *
+ * Returns 0 on success, or a relevant error otherwise.
+ */
+int __nvgpu_mem_create_from_pages(struct gk20a *g, struct nvgpu_mem *dest,
+                                  struct page **pages, int nr_pages);
+
 #endif
diff --git a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
index b01fbec5..66d04ab8 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
@@ -68,6 +68,16 @@ struct nvgpu_mem {
          * therefor zeroed (to prevent leaking information in VIDMEM buffers).
          */
 #define NVGPU_MEM_FLAG_USER_MEM                  (1 << 2)
+
+        /*
+         * Internal flag that specifies this struct has not been made with DMA
+         * memory and as a result should not try to use the DMA routines for
+         * freeing the backing memory.
+         *
+         * However, this will not stop the DMA API from freeing other parts of
+         * nvgpu_mem in a system specific way.
+         */
+#define __NVGPU_MEM_FLAG_NO_DMA                  (1 << 3)
         unsigned long                            mem_flags;
 
         /*