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Commit | Line | Data |
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c8336975 M |
1 | The chosen node |
2 | --------------- | |
3 | The chosen node does not represent a real device, but serves as a place | |
4 | for passing data like which serial device to used to print the logs etc | |
5 | ||
6 | ||
7 | stdout-path property | |
8 | -------------------- | |
9 | Device trees may specify the device to be used for boot console output | |
10 | with a stdout-path property under /chosen. | |
11 | ||
12 | Example | |
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 | ||
25 | tick-timer property | |
26 | ------------------- | |
27 | In a system there are multiple timers, specify which timer to be used | |
28 | as the tick-timer. Earlier it was hardcoded in the timer driver now | |
29 | since device tree has all the timer nodes. Specify which timer to be | |
30 | used as tick timer. | |
31 | ||
32 | Example | |
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 | }; | |
d02d11f8 PT |
44 | |
45 | u-boot,spl-boot-order property | |
46 | ------------------------------ | |
47 | ||
48 | In 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 | |
50 | device may be probed by reading the image and verifying an image | |
51 | signature. | |
52 | ||
53 | If the SPL is configured through the device-tree, the boot-order can | |
54 | be configured with the spl-boot-order property under the /chosen node. | |
55 | Each list element of the property should specify a device to be probed | |
56 | in the order they are listed: references (i.e. implicit paths), a full | |
57 | path or an alias is expected for each entry. | |
58 | ||
80e9f88e PT |
59 | A special specifier "same-as-spl" can be used at any position in the |
60 | boot-order to direct U-Boot to insert the device the SPL was booted | |
61 | from there. Whether this is indeed inserted or silently ignored (if | |
62 | it is not supported on any given SoC/board or if the boot-device is | |
63 | not available to continue booting from) is implementation-defined. | |
64 | Note that if "same-as-spl" expands to an actual node for a given | |
65 | board, the corresponding node may appear multiple times in the | |
66 | boot-order (as there currently exists no mechanism to suppress | |
67 | duplicates from the list). | |
68 | ||
d02d11f8 PT |
69 | Example |
70 | ------- | |
71 | / { | |
72 | chosen { | |
80e9f88e | 73 | u-boot,spl-boot-order = "same-as-spl", &sdmmc, "/sdhci@fe330000"; |
d02d11f8 PT |
74 | }; |
75 | }; |