1The chosen node 2--------------- 3The chosen node does not represent a real device, but serves as a place 4for passing data like which serial device to used to print the logs etc 5 6 7stdout-path property 8-------------------- 9Device trees may specify the device to be used for boot console output 10with a stdout-path property under /chosen. 11 12Example 13------- 14/ { 15 chosen { 16 stdout-path = "/serial@f00:115200"; 17 }; 18 19 serial@f00 { 20 compatible = "vendor,some-uart"; 21 reg = <0xf00 0x10>; 22 }; 23}; 24 25tick-timer property 26------------------- 27In a system there are multiple timers, specify which timer to be used 28as the tick-timer. Earlier it was hardcoded in the timer driver now 29since device tree has all the timer nodes. Specify which timer to be 30used as tick timer. 31 32Example 33------- 34/ { 35 chosen { 36 tick-timer = "/timer2@f00"; 37 }; 38 39 timer2@f00 { 40 compatible = "vendor,some-timer"; 41 reg = <0xf00 0x10>; 42 }; 43}; 44 45u-boot,spl-boot-order property 46------------------------------ 47 48In a system using an SPL stage and having multiple boot sources 49(e.g. SPI NOR flash, on-board eMMC and a removable SD-card), the boot 50device may be probed by reading the image and verifying an image 51signature. 52 53If the SPL is configured through the device-tree, the boot-order can 54be configured with the spl-boot-order property under the /chosen node. 55Each list element of the property should specify a device to be probed 56in the order they are listed: references (i.e. implicit paths), a full 57path or an alias is expected for each entry. 58 59A special specifier "same-as-spl" can be used at any position in the 60boot-order to direct U-Boot to insert the device the SPL was booted 61from there. Whether this is indeed inserted or silently ignored (if 62it is not supported on any given SoC/board or if the boot-device is 63not available to continue booting from) is implementation-defined. 64Note that if "same-as-spl" expands to an actual node for a given 65board, the corresponding node may appear multiple times in the 66boot-order (as there currently exists no mechanism to suppress 67duplicates from the list). 68 69Example 70------- 71/ { 72 chosen { 73 u-boot,spl-boot-order = "same-as-spl", &sdmmc, "/sdhci@fe330000"; 74 }; 75}; 76 77u-boot,spl-boot-device property 78------------------------------- 79 80This property is a companion-property to the u-boot,spl-boot-order and 81will be injected automatically by the SPL stage to notify a later stage 82of where said later stage was booted from. 83 84You should not define this property yourself in the device-tree, as it 85may be overwritten without warning. 86 87firmware-loader property 88------------------------ 89Multiple file system firmware loader nodes could be defined in device trees for 90multiple storage type and their default partition, then a property 91"firmware-loader" can be used to pass default firmware loader 92node(default storage type) to the firmware loader driver. 93 94Example 95------- 96/ { 97 chosen { 98 firmware-loader = &fs_loader0; 99 }; 100 101 fs_loader0: fs-loader@0 { 102 u-boot,dm-pre-reloc; 103 compatible = "u-boot,fs-loader"; 104 phandlepart = <&mmc 1>; 105 }; 106}; 107