gpu: nvgpu: API to access fb memory

Add IOCTL API NVGPU_DBG_GPU_IOCTL_ACCESS_FB_MEMORY
to read/write fb/vidmem memory

Interface will accept dmabuf_fd of the buffer in vidmem,
offset into the buffer to access, temporary buffer
to copy data across API, size of read/write and
command indicating either read or write operation

API will first parse all the inputs, and then call
gk20a_vidbuf_access_memory() to complete fb access

gk20a_vidbuf_access_memory() will then just use
gk20a_mem_rd_n() or gk20a_mem_wr_n() depending
on the command issued

Bug 1804714
Jira DNVGPU-192

Change-Id: Iba3c42410abe12c2884d3b603fa33d27782e4c56
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1255556
(cherry picked from commit 2c49a8a79d93fc526adbf6f808484fa9a3fa2498)
Reviewed-on: http://git-master/r/1260471
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
index 5faff04b..dcc16fba 100644
--- a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
@@ -2301,6 +2301,39 @@ int gk20a_vidmem_get_space(struct gk20a *g, u64 *space)
 #endif
 }
 
+int gk20a_vidbuf_access_memory(struct gk20a *g, struct dma_buf *dmabuf,
+                void *buffer, u64 offset, u64 size, u32 cmd)
+{
+#if defined(CONFIG_GK20A_VIDMEM)
+        struct gk20a_vidmem_buf *vidmem_buf;
+        struct mem_desc *mem;
+        int err = 0;
+
+        if (gk20a_dmabuf_aperture(g, dmabuf) != APERTURE_VIDMEM)
+                return -EINVAL;
+
+        vidmem_buf = dmabuf->priv;
+        mem = vidmem_buf->mem;
+
+        switch (cmd) {
+        case NVGPU_DBG_GPU_IOCTL_ACCESS_FB_MEMORY_CMD_READ:
+                gk20a_mem_rd_n(g, mem, offset, buffer, size);
+                break;
+
+        case NVGPU_DBG_GPU_IOCTL_ACCESS_FB_MEMORY_CMD_WRITE:
+                gk20a_mem_wr_n(g, mem, offset, buffer, size);
+                break;
+
+        default:
+                err = -EINVAL;
+        }
+
+        return err;
+#else
+        return -ENOSYS;
+#endif
+}
+
 static u64 gk20a_mm_get_align(struct gk20a *g, struct scatterlist *sgl,
                               enum gk20a_aperture aperture)
 {