[PATCH 1/6] drm: Add helper to cast DMA-buf to GEM object

[Felix Kuehling]

Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
 drivers/gpu/drm/drm_prime.c | 25 +++++++++++++++++++++++++
 include/drm/drmP.h          |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 25aa455..b1f8445 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -594,6 +594,31 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 
 /**
+ * drm_gem_prime_dmabuf_to_object - try to cast dmabuf to GEM object
+ * @dma_buf: dma-buf object to cast
+ * @driver: driver that is the expected exporter of the dma-buf
+ *
+ * If @dma_buf represents a GEM object, this function return a pointer
+ * to it. Optionally, if @driver is not NULL, it also checks that the
+ * object was exported by @driver. Otherwise it returns NULL.
+ */
+struct drm_gem_object *drm_gem_prime_dmabuf_to_object(struct dma_buf *dma_buf,
+						      struct drm_driver *driver)
+{
+	struct drm_gem_object *obj;
+
+	if (dma_buf->ops != &drm_gem_prime_dmabuf_ops)
+		return NULL;
+
+	obj = dma_buf->priv;
+	if (driver && obj->dev->driver != driver)
+		return NULL;
+
+	return obj;
+}
+EXPORT_SYMBOL(drm_gem_prime_dmabuf_to_object);
+
+/**
  * drm_gem_prime_import - helper library implementation of the import callback
  * @dev: drm_device to import into
  * @dma_buf: dma-buf object to import
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 6105c05..79c2b23 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -767,6 +767,8 @@ extern struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
 extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 		struct drm_file *file_priv, uint32_t handle, uint32_t flags,
 		int *prime_fd);
+extern struct drm_gem_object *drm_gem_prime_dmabuf_to_object(
+		struct dma_buf *dma_buf, struct drm_driver *driver);
 extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 		struct dma_buf *dma_buf);
 extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
-- 
1.9.1