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301ea68621
Certain boards come in different variations by way of utilizing daughter
boards, for example. These boards might contain additional chips, which
are added to the main board's busses, e.g. I2C.
The device tree support for such boards would either, quite naturally,
employ the overlay mechanism to add such chips to the tree, or would use
one large default device tree, and delete the devices that are actually
not present.
Regardless of approach, even on the U-Boot level, a modification of the
device tree is a prerequisite to have such modular families of boards
supported properly.
Therefore, we add an option to make the U-Boot device tree (the actual
copy later used by the driver model) writeable, and add a callback
method that allows boards to modify the device tree at an early stage,
at which, hopefully, also the application of device tree overlays will
be possible.
Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Stefan Roese <sr@denx.de>
(cherry picked from commit 2a792753d6)
Signed-off-by: Ram Kumar D <quic_ramd@quicinc.com>
Change-Id: I9a5fe4c6d681aaa5c68edd8a2a39d36bf2340fdf
84 lines
2.7 KiB
Text
84 lines
2.7 KiB
Text
#
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# Device Tree Control
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#
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config SUPPORT_OF_CONTROL
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bool
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menu "Device Tree Control"
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depends on SUPPORT_OF_CONTROL
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config OF_CONTROL
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bool "Run-time configuration via Device Tree"
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help
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This feature provides for run-time configuration of U-Boot
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via a flattened device tree.
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config OF_BOARD_FIXUP
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bool "Board-specific manipulation of Device Tree"
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help
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In certain circumstances it is necessary to be able to modify
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U-Boot's device tree (e.g. to delete device from it). This option
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make the Device Tree writeable and provides a board-specific
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"board_fix_fdt" callback (called during pre-relocation time), which
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enables the board initialization to modifiy the Device Tree. The
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modified copy is subsequently used by U-Boot after relocation.
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config SPL_OF_CONTROL
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bool "Enable run-time configuration via Device Tree in SPL"
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depends on SPL && OF_CONTROL
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help
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Some boards use device tree in U-Boot but only have 4KB of SRAM
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which is not enough to support device tree. Enable this option to
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allow such boards to be supported by U-Boot SPL.
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choice
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prompt "Provider of DTB for DT control"
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depends on OF_CONTROL
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config OF_SEPARATE
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bool "Separate DTB for DT control"
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depends on !SANDBOX
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help
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If this option is enabled, the device tree will be built and
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placed as a separate u-boot.dtb file alongside the U-Boot image.
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config OF_EMBED
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bool "Embedded DTB for DT control"
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help
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If this option is enabled, the device tree will be picked up and
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built into the U-Boot image. This is suitable for local debugging
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and development only and is not recommended for production devices.
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Boards in the mainline U-Boot tree should not use it.
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config OF_HOSTFILE
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bool "Host filed DTB for DT control"
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depends on SANDBOX
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help
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If this option is enabled, DTB will be read from a file on startup.
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This is only useful for Sandbox. Use the -d flag to U-Boot to
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specify the file to read.
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endchoice
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config DEFAULT_DEVICE_TREE
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string "Default Device Tree for DT control"
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help
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This option specifies the default Device Tree used for DT control.
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It can be overridden from the command line:
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$ make DEVICE_TREE=<device-tree-name>
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config OF_SPL_REMOVE_PROPS
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string "List of device tree properties to drop for SPL"
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depends on SPL_OF_CONTROL
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default "clocks clock-names interrupt-parent" if SPL_PINCTRL_FULL
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default "pinctrl-0 pinctrl-names clocks clock-names interrupt-parent"
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help
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Since SPL normally runs in a reduced memory space, the device tree
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is cut down to only what is needed to load and start U-Boot. Only
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nodes marked with the property "u-boot,dm-pre-reloc" will be
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included. In addition, some properties are not used by U-Boot and
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can be discarded. This option defines the list of properties to
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discard.
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endmenu
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