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1 #
2 # Device Tree Control
3 #
4
5 config SUPPORT_OF_CONTROL
6 bool
7
8 menu "Device Tree Control"
9 depends on SUPPORT_OF_CONTROL
10
11 config OF_CONTROL
12 bool "Run-time configuration via Device Tree"
13 help
14 This feature provides for run-time configuration of U-Boot
15 via a flattened device tree.
16
17 config OF_BOARD_FIXUP
18 bool "Board-specific manipulation of Device Tree"
19 help
20 In certain circumstances it is necessary to be able to modify
21 U-Boot's device tree (e.g. to delete device from it). This option
22 make the Device Tree writeable and provides a board-specific
23 "board_fix_fdt" callback (called during pre-relocation time), which
24 enables the board initialization to modifiy the Device Tree. The
25 modified copy is subsequently used by U-Boot after relocation.
26
27 config SPL_OF_CONTROL
28 bool "Enable run-time configuration via Device Tree in SPL"
29 depends on SPL && OF_CONTROL
30 help
31 Some boards use device tree in U-Boot but only have 4KB of SRAM
32 which is not enough to support device tree. Enable this option to
33 allow such boards to be supported by U-Boot SPL.
34
35 config OF_LIVE
36 bool "Enable use of a live tree"
37 depends on OF_CONTROL
38 help
39 Normally U-Boot uses a flat device tree which saves space and
40 avoids the need to unpack the tree before use. However a flat
41 tree does not support modifcation from within U-Boot since it
42 can invalidate driver-model device tree offsets. This option
43 enables a live tree which is available after relocation,
44 and can be adjusted as needed.
45
46 choice
47 prompt "Provider of DTB for DT control"
48 depends on OF_CONTROL
49
50 config OF_SEPARATE
51 bool "Separate DTB for DT control"
52 depends on !SANDBOX
53 help
54 If this option is enabled, the device tree will be built and
55 placed as a separate u-boot.dtb file alongside the U-Boot image.
56
57 config OF_EMBED
58 bool "Embedded DTB for DT control"
59 help
60 If this option is enabled, the device tree will be picked up and
61 built into the U-Boot image. This is suitable for local debugging
62 and development only and is not recommended for production devices.
63 Boards in the mainline U-Boot tree should not use it.
64
65 config OF_BOARD
66 bool "Provided by the board at runtime"
67 depends on !SANDBOX
68 help
69 If this option is enabled, the device tree will be provided by
70 the board at runtime if the board supports it, instead of being
71 bundled with the image.
72
73 config OF_HOSTFILE
74 bool "Host filed DTB for DT control"
75 depends on SANDBOX
76 help
77 If this option is enabled, DTB will be read from a file on startup.
78 This is only useful for Sandbox. Use the -d flag to U-Boot to
79 specify the file to read.
80
81 endchoice
82
83 config DEFAULT_DEVICE_TREE
84 string "Default Device Tree for DT control"
85 depends on OF_CONTROL
86 help
87 This option specifies the default Device Tree used for DT control.
88 It can be overridden from the command line:
89 $ make DEVICE_TREE=<device-tree-name>
90
91 config OF_LIST
92 string "List of device tree files to include for DT control"
93 depends on SPL_LOAD_FIT
94 default DEFAULT_DEVICE_TREE
95 help
96 This option specifies a list of device tree files to use for DT
97 control. These will be packaged into a FIT. At run-time, SPL will
98 select the correct DT to use by examining the hardware (e.g.
99 reading a board ID value). This is a list of device tree files
100 (without the directory or .dtb suffix) separated by <space>.
101
102 config OF_SPL_REMOVE_PROPS
103 string "List of device tree properties to drop for SPL"
104 depends on SPL_OF_CONTROL
105 default "interrupt-parent" if SPL_PINCTRL && SPL_CLK
106 default "clocks clock-names interrupt-parent" if SPL_PINCTRL
107 default "pinctrl-0 pinctrl-names interrupt-parent" if SPL_CLK
108 default "pinctrl-0 pinctrl-names clocks clock-names interrupt-parent"
109 help
110 Since SPL normally runs in a reduced memory space, the device tree
111 is cut down to only what is needed to load and start U-Boot. Only
112 nodes marked with the property "u-boot,dm-pre-reloc" will be
113 included. In addition, some properties are not used by U-Boot and
114 can be discarded. This option defines the list of properties to
115 discard.
116
117 config SPL_OF_PLATDATA
118 bool "Generate platform data for use in SPL"
119 depends on SPL_OF_CONTROL
120 help
121 For very constrained SPL environments the overhead of decoding
122 device tree nodes and converting their contents into platform data
123 is too large. This overhead includes libfdt code as well as the
124 device tree contents itself. The latter is fairly compact, but the
125 former can add 3KB or more to a Thumb 2 Image.
126
127 This option enables generation of platform data from the device
128 tree as C code. This code creates devices using U_BOOT_DEVICE()
129 declarations. The benefit is that it allows driver code to access
130 the platform data directly in C structures, avoidin the libfdt
131 overhead.
132
133 This option works by generating C structure declarations for each
134 compatible string, then adding platform data and U_BOOT_DEVICE
135 declarations for each node. See README.platdata for more
136 information.
137
138 endmenu