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Commit 2a9d832c authored by Leif Lindholm's avatar Leif Lindholm Committed by Grant Likely
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of: Add bindings for chosen node, stdout-path 



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: default avatarLeif Lindholm <leif.lindholm@linaro.org>
[grant.likely: remove reference to uart_parse_options]
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarGrant Likely <grant.likely@linaro.org>
parent 63ebecc0

Documentation/devicetree/bindings/chosen.txt

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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

--------------------



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@f00:115200";

	};



	serial@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 preferred binding is a string in the form:



	<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



Implementation note: Linux will look for the property "linux,stdout-path" or

on PowerPC "stdout" if "stdout-path" is not found.  However, the

"linux,stdout-path" and "stdout" properties are deprecated. New platforms

should only use the "stdout-path" property.