RT-Thread RTOS
An open source embedded real-time operating system
OFW platform enumeration

Platform bus enumeration (<tt>platform_ofw.c</tt>)

Walk the unflattened tree and register **struct rt_platform_device** for driver **probe**. Core OFW APIs: OFW nodes and properties.

Source: **components/drivers/core/platform_ofw.c**. Platform driver API: Platform bus.

Probe order

**INIT_PLATFORM_EXPORT(platform_ofw_device_probe)**:

  1. **/clocks** subtree (providers before consumers)
  2. **/** root (depth-first)
  3. **/firmware**
  4. **/chosen/simple-framebuffer** (if present)

Child walk

For each available child of **parent_np**:

Skip when Reason
**np->dev set** Already instantiated
**RT_OFW_F_SYSTEM or RT_OFW_F_READLY** Meta or bound node
No **compatible** and no real name Anonymous container
**compatible in platform_ofw_ids** Action
**simple-bus**, **simple-mfd**, **isa**, **arm,amba-bus** Recurse **platform_ofw_device_probe_once(np)** first
Leaf **alloc_ofw_platform_device** → **rt_platform_device_register**

**ofw_device_rename**: **reg**-based name (lx.%.*s) when decodable, else hierarchical path.

<tt>rt_platform_ofw_request</tt>

rt_err_t rt_platform_ofw_request(struct rt_ofw_node *np);
State Behavior
No **np->dev** Create pdev, register (runs **probe**)
**dev without driver** **rt_bus_reload_driver_device**
Probed **RT_EOK**

Call from consumers after **rt_ofw_parse_phandle_cells** when provider **rt_ofw_data** is NULL.

Other APIs

API Role
**rt_platform_ofw_device_probe_child** Register single child under non-root parent
**rt_platform_ofw_free** Clear **RT_OFW_F_PLATFORM**, **rt_ofw_node_put**, free pdev

Pitfalls

Issue Mitigation
Clock provider late Ensure **/clocks** nodes probe first (built-in order)
No **rt_platform_ofw_request** Provider never probes — phandle parse succeeds but **rt_ofw_data** NULL
Bus not in **platform_ofw_ids** Children still register as leaf platform devices if **compatible** present

See also