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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,bootcount-device property
- --------------------------------
- In a DM-based system, the bootcount may be stored in a device known to
- the DM framework (e.g. in a battery-backed SRAM area within a RTC
- device) managed by a device conforming to UCLASS_BOOTCOUNT. If
- multiple such devices are present in a system concurrently, then the
- u-boot,bootcount-device property can select the preferred target.
- Example
- -------
- / {
- chosen {
- u-boot,bootcount-device = &bootcount-rv3029;
- };
- bootcount-rv3029: bootcount@0 {
- compatible = "u-boot,bootcount-rtc";
- rtc = &rv3029;
- offset = <0x38>;
- };
- i2c2 {
- rv3029: rtc@56 {
- compatible = "mc,rv3029";
- reg = <0x56>;
- };
- };
- };
- 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.
- A special specifier "same-as-spl" can be used at any position in the
- boot-order to direct U-Boot to insert the device the SPL was booted
- from there. Whether this is indeed inserted or silently ignored (if
- it is not supported on any given SoC/board or if the boot-device is
- not available to continue booting from) is implementation-defined.
- Note that if "same-as-spl" expands to an actual node for a given
- board, the corresponding node may appear multiple times in the
- boot-order (as there currently exists no mechanism to suppress
- duplicates from the list).
- Example
- -------
- / {
- chosen {
- u-boot,spl-boot-order = "same-as-spl", &sdmmc, "/sdhci@fe330000";
- };
- };
- u-boot,spl-boot-device property
- -------------------------------
- This property is a companion-property to the u-boot,spl-boot-order and
- will be injected automatically by the SPL stage to notify a later stage
- of where said later stage was booted from.
- You should not define this property yourself in the device-tree, as it
- may be overwritten without warning.
- firmware-loader property
- ------------------------
- Multiple file system firmware loader nodes could be defined in device trees for
- multiple storage type and their default partition, then a property
- "firmware-loader" can be used to pass default firmware loader
- node(default storage type) to the firmware loader driver.
- Example
- -------
- / {
- chosen {
- firmware-loader = &fs_loader0;
- };
- fs_loader0: fs-loader@0 {
- u-boot,dm-pre-reloc;
- compatible = "u-boot,fs-loader";
- phandlepart = <&mmc 1>;
- };
- };
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