drm: add mmap function to prime helpers

This adds to call low-level mmap() from prime helpers.

Signed-off-by: Joonyoung Shim <[e-mail]>
Acked-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/drm_prime.c

···
 static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
 		struct vm_area_struct *vma)
 {
-	return -EINVAL;
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	if (!dev->driver->gem_prime_mmap)
+		return -ENOSYS;
+
+	return dev->driver->gem_prime_mmap(obj, vma);
 }
 
 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {

include/drm/drmP.h

···
 				struct sg_table *sgt);
 	void *(*gem_prime_vmap)(struct drm_gem_object *obj);
 	void (*gem_prime_vunmap)(struct drm_gem_object *obj, void *vaddr);
+	int (*gem_prime_mmap)(struct drm_gem_object *obj,
+				struct vm_area_struct *vma);
 
 	/* vga arb irq handler */
 	void (*vgaarb_irq)(struct drm_device *dev, bool state);