OFW core (<tt>base.c</tt>, <tt>ofw.c</tt>)
Node tree, properties, phandles, matching, stubs, and **rt_ofw_parse_object**. Boot: OFW boot and FDT. IO: OFW addressing and MMIO. IRQ: OFW interrupts.
Headers: **drivers/ofw.h**. Sources: **components/drivers/ofw/base.c**, **ofw.c**.
Core types
| Type | Role |
**struct rt_ofw_prop** | Property list entry: **name**, **length**, **value** |
**struct rt_ofw_node** | **full_name**, **phandle**, **props**, tree links, **ref**, **flags**, **rt_data**, optional **dev** |
**struct rt_ofw_cell_args** | Parsed phandle + specifier (**args[]**, max **RT_OFW_MAX_CELL_ARGS**) |
**struct rt_ofw_node_id** | **compatible** / **name** / **type** match table row |
**struct rt_ofw_stub** | Early probe: **ids**, **handler(np, id)** |
Node flags (<tt>RT_OFW_F_*</tt>)
| Flag | Meaning |
**RT_OFW_F_SYSTEM** | Meta node (/, /cpus, /chosen, …) — platform walk skips |
**RT_OFW_F_READLY** | Stub or driver already bound |
**RT_OFW_F_PLATFORM** | **rt_platform_device** created |
**RT_OFW_F_OVERLAY** | From applied DT overlay |
APIs: **rt_ofw_node_set_flag**, **rt_ofw_node_test_flag**, **rt_ofw_node_clear_flag**.
Lifetime
| API | Role |
**rt_ofw_node_get / rt_ofw_node_put** | Reference count on **np** |
**rt_ofw_node_destroy** | Tear down subtree when applicable |
**rt_ofw_data(np)** | Driver private pointer in **np->rt_data** |
Finding nodes
| API | Role |
**rt_ofw_find_node_by_path** | Absolute path (/soc/uart@1000) |
**rt_ofw_find_node_by_compatible** | DFS from **from** (**RT_NULL** = whole tree) |
**rt_ofw_find_node_by_ids / _r** | Match **rt_ofw_node_id** table |
**rt_ofw_find_node_by_phandle** | Resolve numeric phandle |
**rt_ofw_find_node_by_name**, **_by_prop**, **_by_tag**, **_by_type** | Other keys |
**rt_ofw_get_parent**, **rt_ofw_get_next_*** | Walk tree |
**rt_ofw_foreach_* macros** | Prefer macros in **ofw.h** over manual sibling loops |
Availability: **rt_ofw_node_is_available** (**status**), **rt_ofw_machine_is_compatible** (root).
Properties
| API | Role |
**rt_ofw_get_prop** | Find property by name |
**rt_ofw_prop_read_raw** | Blob + length |
**rt_ofw_prop_read_u8/u16/u32/s32/u64/string/bool** | Typed index 0 |
**rt_ofw_prop_read_*_index**, ***_array_index** | Multi-element |
**rt_ofw_prop_count_of_u32** (etc.) | Element count |
**rt_ofw_append_prop** | Runtime append (rare) |
Phandles
| API | Role |
**rt_ofw_parse_phandle** | Single phandle property by index |
**rt_ofw_parse_phandle_cells** | List + **#*-cells** → **rt_ofw_cell_args** |
**rt_ofw_count_phandle_cells** | Entry count in list |
**rt_ofw_parse_object** | Find named object in composite **rt_ofw_data** |
**ofw.c** registers **#clock-cells**, **#reset-cells**, **#power-domain-cells** object layouts when those subsystems are enabled.
Matching and stubs
| API / macro | Role |
**rt_ofw_node_match**, **rt_ofw_prop_match** | Match **compatible** against **rt_ofw_node_id[]** |
**RT_OFW_STUB_EXPORT** | Link stub into **.rt_ofw_data.stub.*** |
**rt_ofw_stub_probe_range** | Run stubs on a node (class ranges via **RT_OFW_STUB_RANGE_EXPORT**) |
Used by early serial, hwcache, and other non-platform bindings.
Aliases and CPU
| API | Role |
**rt_ofw_get_alias_node**, **rt_ofw_get_alias_id** | **/aliases** resolution |
**rt_ofw_get_cpu_node**, **rt_ofw_foreach_cpu_node** | CPU nodes under **/cpus** |
**rt_ofw_get_cpu_id**, **rt_ofw_get_cpu_hwid** | MPIDR / hardware ID |
**rt_ofw_map_id** | Generic ***-map** / ***-map-mask** lookup |
**ofw_alias_scan** runs during unflatten (**base.c**).
Console and debug
| API | Role |
**rt_ofw_console_setup** | Console from **/chosen** |
**rt_ofw_node_dump_dts** | Print subtree as DTS-like text (**RT_USING_CONSOLE**) |
Pitfalls
| Issue | Mitigation |
Leaked **np** | Always **put** after **get** |
| Wrong phandle index | Check **rt_ofw_count_phandle_cells** and ***-names** |
**compatible order** | Most specific first in driver **ids[]** |
**rt_ofw_data before probe** | **rt_platform_ofw_request** on provider |
See also
1.9.1