u-boot/doc/device-tree-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 like which serial device to used to print the logs etc
stdout-path property
--------------------
Device trees may specify the device to be used for boot console output
with a stdout-path property under /chosen.
Example
-------
/ {
chosen {
stdout-path = "/serial@f00:115200";
};
serial@f00 {
compatible = "vendor,some-uart";
reg = <0xf00 0x10>;
};
};
tick-timer property
-------------------
In a system there are multiple timers, specify which timer to be used
as the tick-timer. Earlier it was hardcoded in the timer driver now
since device tree has all the timer nodes. Specify which timer to be
used as tick timer.
Example
-------
/ {
chosen {
tick-timer = "/timer2@f00";
};
timer2@f00 {
compatible = "vendor,some-timer";
reg = <0xf00 0x10>;
};
};
u-boot,spl-boot-order property
------------------------------
In a system using an SPL stage and having multiple boot sources
(e.g. SPI NOR flash, on-board eMMC and a removable SD-card), the boot
device may be probed by reading the image and verifying an image
signature.
If the SPL is configured through the device-tree, the boot-order can
be configured with the spl-boot-order property under the /chosen node.
Each list element of the property should specify a device to be probed
in the order they are listed: references (i.e. implicit paths), a full
path or an alias is expected for each entry.
Example
-------
/ {
chosen {
u-boot,spl-boot-order = &sdmmc, "/sdhci@fe330000";
};
};