Commit | Line | Data |
---|---|---|
2a9d832c LL |
1 | The chosen node |
2 | --------------- | |
3 | ||
4 | The chosen node does not represent a real device, but serves as a place | |
5 | for passing data between firmware and the operating system, like boot | |
6 | arguments. Data in the chosen node does not represent the hardware. | |
7 | ||
8 | ||
9 | stdout-path property | |
10 | -------------------- | |
11 | ||
12 | Device trees may specify the device to be used for boot console output | |
13 | with a stdout-path property under /chosen, as described in ePAPR, e.g. | |
14 | ||
15 | / { | |
16 | chosen { | |
17 | stdout-path = "/serial@f00:115200"; | |
18 | }; | |
19 | ||
20 | serial@f00 { | |
21 | compatible = "vendor,some-uart"; | |
22 | reg = <0xf00 0x10>; | |
23 | }; | |
24 | }; | |
25 | ||
26 | If the character ":" is present in the value, this terminates the path. | |
27 | The meaning of any characters following the ":" is device-specific, and | |
28 | must be specified in the relevant binding documentation. | |
29 | ||
30 | For UART devices, the preferred binding is a string in the form: | |
31 | ||
32 | <baud>{<parity>{<bits>{<flow>}}} | |
33 | ||
34 | where | |
35 | ||
36 | baud - baud rate in decimal | |
37 | parity - 'n' (none), 'o', (odd) or 'e' (even) | |
38 | bits - number of data bits | |
39 | flow - 'r' (rts) | |
40 | ||
41 | For example: 115200n8r | |
42 | ||
43 | Implementation note: Linux will look for the property "linux,stdout-path" or | |
44 | on PowerPC "stdout" if "stdout-path" is not found. However, the | |
45 | "linux,stdout-path" and "stdout" properties are deprecated. New platforms | |
46 | should only use the "stdout-path" property. |