[PATCH v2 1/2] drm/shmem-helper: Add .gem_create_object helper that sets map_cached flag

[Thomas Zimmermann]

The helper drm_gem_shmem_create_object_cached() allocates an GEM SHMEM
object and sets the map_cached flag. Useful for drivers that want cached
mappings.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 27 ++++++++++++++++++++++++++
 include/drm/drm_gem_shmem_helper.h     |  4 ++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index df31e5782eed1..ab28b7ff864cb 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -433,6 +433,33 @@ bool drm_gem_shmem_purge(struct drm_gem_object *obj)
 }
 EXPORT_SYMBOL(drm_gem_shmem_purge);
 
+/**
+ * drm_gem_shmem_create_object_cached - Create a shmem buffer object with
+ *                                      cached mappings
+ * @dev: DRM device
+ * @size: Size of the object to allocate
+ *
+ * By default, shmem buffer objects use writecombine mappings. This
+ * function implements struct drm_driver.gem_create_object for shmem
+ * buffer objects with cached mappings.
+ *
+ * Returns:
+ * A struct drm_gem_shmem_object * on success or NULL negative on failure.
+ */
+struct drm_gem_object *
+drm_gem_shmem_create_object_cached(struct drm_device *dev, size_t size)
+{
+       struct drm_gem_shmem_object *shmem;
+
+       shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
+       if (!shmem)
+               return NULL;
+       shmem->map_cached = true;
+
+       return &shmem->base;
+}
+EXPORT_SYMBOL(drm_gem_shmem_create_object_cached);
+
 /**
  * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
  * @file: DRM file structure to create the dumb buffer for
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 294b2931c4cc0..5381f0c8cf6f6 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -132,6 +132,10 @@ struct drm_gem_shmem_object *
 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 				 struct drm_device *dev, size_t size,
 				 uint32_t *handle);
+
+struct drm_gem_object *
+drm_gem_shmem_create_object_cached(struct drm_device *dev, size_t size);
+
 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
 			      struct drm_mode_create_dumb *args);
 
-- 
2.26.2