initr_dm
dm_init_and_scan
dm_init ((1)创建根设备root的udevice,存放在gd->dm_root中 (2)初始化uclass链表gd->uclass_root)
dm_scan_platdata 跳过
dm_extended_scan_fdt
dm_scan_fdt
dm_scan_fdt_node
lists_bind_fdt
device_bind_with_driver_data
device_bind_common