[PATCH v3 1/3] devicetree: of: Add bindings for chosen node, stdout-path
From: Frank Rowand <hidden>
Date: 2014-12-03 02:24:57
Also in:
linux-devicetree, lkml
On 11/27/2014 9:56 AM, Leif Lindholm wrote:
quoted hunk ↗ jump to hunk
Add a global binding for the chosen node. Include a description of the stdout-path, and an explicit statement on its extra options in the context of a UART console. Opening description stolen from www.devicetree.org, and part of the remaining text provided by Mark Rutland. Signed-off-by: Leif Lindholm <redacted> --- Documentation/devicetree/bindings/chosen.txt | 42 ++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 Documentation/devicetree/bindings/chosen.txtdiff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt new file mode 100644 index 0000000..9cd74e9 --- /dev/null +++ b/Documentation/devicetree/bindings/chosen.txt@@ -0,0 +1,42 @@ +The chosen node +--------------- + +The chosen node does not represent a real device, but serves as a place +for passing data between firmware and the operating system, like boot +arguments. Data in the chosen node does not represent the hardware. + + +stdout-path property
The code in patch 3/3 adds the extra options feature to the properties: stdout-path linux,stdout-path stdout [if (IS_ENABLED(CONFIG_PPC) ... ]
+--------------------
+
+Device trees may specify the device to be used for boot console output
+with a stdout-path property under /chosen, as described in ePAPR, e.g.
+
+/ {
+ chosen {
+ stdout-path = "/serial at f00:115200";
+ };
+
+ serial at f00 {
+ compatible = "vendor,some-uart";
+ reg = <0xf00 0x10>;
+ };
+};
+
+If the character ":" is present in the value, this terminates the path.
+The meaning of any characters following the ":" is device-specific, and
+must be specified in the relevant binding documentation.
+
+For UART devices, the format supported by uart_parse_options() is the
+expected one. In this case, the format of the string is:
+
+ <baud>{<parity>{<bits>{<flow>}}}
+
+where
+
+ baud - baud rate in decimal
+ parity - 'n' (none), 'o', (odd) or 'e' (even)
+ bits - number of data bits
+ flow - 'r' (rts)
+
+For example: 115200n8r