drm/ttm: provide a driver-led init path for range mm manager. (v2)

This lets the generic range mm manager be initialised by the driver.

v2: add docs.
rename api to range_man_init for now.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804025632.3868079-15-airlied@gmail.com

drivers/gpu/drm/ttm/ttm_bo_manager.c

@@ -104,7 +104,7 @@ static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
 	}
 }
 
-static int ttm_bo_man_init(struct ttm_mem_type_manager *man,
+static int ttm_bo_man_init_private(struct ttm_mem_type_manager *man,
 				   unsigned long p_size)
 {
 	struct ttm_range_manager *rman;
@@ -119,6 +119,23 @@ static int ttm_bo_man_init(struct ttm_mem_type_manager *man,
 	return 0;
 }
 
+int ttm_range_man_init(struct ttm_bo_device *bdev,
+		       struct ttm_mem_type_manager *man,
+		       unsigned long p_size)
+{
+	int ret;
+
+	man->func = &ttm_bo_manager_func;
+
+	ttm_mem_type_manager_init(bdev, man, p_size);
+	ret = ttm_bo_man_init_private(man, p_size);
+	if (ret)
+		return ret;
+	ttm_mem_type_manager_set_used(man, true);
+	return 0;
+}
+EXPORT_SYMBOL(ttm_range_man_init);
+
 static int ttm_bo_man_takedown(struct ttm_mem_type_manager *man)
 {
 	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
@@ -147,7 +164,7 @@ static void ttm_bo_man_debug(struct ttm_mem_type_manager *man,
 }
 
 const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
-	.init = ttm_bo_man_init,
+	.init = ttm_bo_man_init_private,
 	.takedown = ttm_bo_man_takedown,
 	.get_node = ttm_bo_man_get_node,
 	.put_node = ttm_bo_man_put_node,

include/drm/ttm/ttm_bo_driver.h

@@ -819,6 +819,20 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
  */
 pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
 
+/**
+ * ttm_range_man_init
+ *
+ * @bdev: ttm device
+ * @man: the manager to initialise with the range manager.
+ * @p_size: size of area to be managed in pages.
+ *
+ * Initialise a generic range manager for the selected memory type.
+ * The range manager is installed for this device in the type slot.
+ */
+int ttm_range_man_init(struct ttm_bo_device *bdev,
+		       struct ttm_mem_type_manager *man,
+		       unsigned long p_size);
+
 extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
 
 /**