drm/gem: add functions for mmap offset creation

Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 91 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 186d62eb063b..396e60ce8114 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -285,6 +285,94 @@ again:
 }
 EXPORT_SYMBOL(drm_gem_handle_create);
 
+
+/**
+ * drm_gem_free_mmap_offset - release a fake mmap offset for an object
+ * @obj: obj in question
+ *
+ * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
+ */
+void
+drm_gem_free_mmap_offset(struct drm_gem_object *obj)
+{
+        struct drm_device *dev = obj->dev;
+        struct drm_gem_mm *mm = dev->mm_private;
+        struct drm_map_list *list = &obj->map_list;
+
+        drm_ht_remove_item(&mm->offset_hash, &list->hash);
+        drm_mm_put_block(list->file_offset_node);
+        kfree(list->map);
+        list->map = NULL;
+}
+EXPORT_SYMBOL(drm_gem_free_mmap_offset);
+
+/**
+ * drm_gem_create_mmap_offset - create a fake mmap offset for an object
+ * @obj: obj in question
+ *
+ * GEM memory mapping works by handing back to userspace a fake mmap offset
+ * it can use in a subsequent mmap(2) call.  The DRM core code then looks
+ * up the object based on the offset and sets up the various memory mapping
+ * structures.
+ *
+ * This routine allocates and attaches a fake offset for @obj.
+ */
+int
+drm_gem_create_mmap_offset(struct drm_gem_object *obj)
+{
+        struct drm_device *dev = obj->dev;
+        struct drm_gem_mm *mm = dev->mm_private;
+        struct drm_map_list *list;
+        struct drm_local_map *map;
+        int ret = 0;
+
+        /* Set the object up for mmap'ing */
+        list = &obj->map_list;
+        list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
+        if (!list->map)
+                return -ENOMEM;
+
+        map = list->map;
+        map->type = _DRM_GEM;
+        map->size = obj->size;
+        map->handle = obj;
+
+        /* Get a DRM GEM mmap offset allocated... */
+        list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
+                        obj->size / PAGE_SIZE, 0, 0);
+
+        if (!list->file_offset_node) {
+                DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
+                ret = -ENOSPC;
+                goto out_free_list;
+        }
+
+        list->file_offset_node = drm_mm_get_block(list->file_offset_node,
+                        obj->size / PAGE_SIZE, 0);
+        if (!list->file_offset_node) {
+                ret = -ENOMEM;
+                goto out_free_list;
+        }
+
+        list->hash.key = list->file_offset_node->start;
+        ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
+        if (ret) {
+                DRM_ERROR("failed to add to map hash\n");
+                goto out_free_mm;
+        }
+
+        return 0;
+
+out_free_mm:
+        drm_mm_put_block(list->file_offset_node);
+out_free_list:
+        kfree(list->map);
+        list->map = NULL;
+
+        return ret;
+}
+EXPORT_SYMBOL(drm_gem_create_mmap_offset);
+
 /** Returns a reference to the object named by the handle. */
 struct drm_gem_object *
 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 9b7c2bb4bb44..43538b643560 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1624,6 +1624,9 @@ drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
         drm_gem_object_unreference_unlocked(obj);
 }
 
+void drm_gem_free_mmap_offset(struct drm_gem_object *obj);
+int drm_gem_create_mmap_offset(struct drm_gem_object *obj);
+
 struct drm_gem_object *drm_gem_object_lookup(struct drm_device *dev,
                                              struct drm_file *filp,
                                              u32 handle);