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70 lines
1.8 KiB
ReStructuredText
70 lines
1.8 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0+
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fdt command
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===========
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Synopis
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-------
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::
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fdt addr [-cq] [addr [len]]
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Description
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-----------
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The fdt command provides access to flat device tree blobs in memory. It has
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many subcommands, some of which are not documented here.
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Flags:
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-c
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Select the control FDT (otherwise the working FDT is used).
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-q
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Don't display errors
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The control FDT is the one used by U-Boot itself to control various features,
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including driver model. This should only be changed if you really know what you
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are doing, since once U-Boot starts it maintains pointers into the FDT from the
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various driver model data structures.
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The working FDT is the one passed to the Operating System when booting. This
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can be freely modified, so far as U-Boot is concerned, since it does not affect
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U-Boot's operation.
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fdt addr
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~~~~~~~~
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With no arguments, this shows the address of the current working or control
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FDT.
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If the `addr` argument is provided, then this sets the address of the working or
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control FDT to the provided address.
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If the `len` argument is provided, then the device tree is expanded to that
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size. This can be used to make space for more nodes and properties. It is
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assumed that there is enough space in memory for this expansion.
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Example
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-------
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Get the control address and copy that FDT to free memory::
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=> fdt addr -c
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Control fdt: 0aff9fd0
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=> cp.b 0aff9fd0 10000 10000
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=> md 10000 4
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00010000: edfe0dd0 5b3d0000 78000000 7c270000 ......=[...x..'|
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The second word shows the size of the FDT. Now set the working FDT to that
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address and expand it to 0xf000 in size::
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=> fdt addr 10000 f000
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=> md 10000 4
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00010000: edfe0dd0 00f00000 78000000 7c270000 ...........x..'|
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Return value
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------------
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The return value $? indicates whether the command succeeded.
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