Commit 3e9fddfc authored by Simon Glass's avatar Simon Glass Committed by Heinrich Schuchardt
Browse files

doc: Move devicetree control doc to rST



Move this to rST format, largely unchanged to start with. Add an index
for this topic, as well as an empty intro.

Note this patch does not include updates! Is it just a conversion to the
new format. See the next patch.
Signed-off-by: Simon Glass's avatarSimon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt's avatarHeinrich Schuchart <xypron.glpk@gmx.de>
parent 00e80da9
# SPDX-License-Identifier: GPL-2.0+
#
# Copyright (c) 2011 The Chromium OS Authors.
.. SPDX-License-Identifier: GPL-2.0+
.. sectionauthor:: Copyright 2011 The Chromium OS Authors
Device Tree Control in U-Boot
=============================
......@@ -37,9 +36,7 @@ What is a Flat Device Tree?
---------------------------
An fdt can be specified in source format as a text file. To read about
the fdt syntax, take a look at the specification here:
https://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf
the fdt syntax, take a look at the specification (dtspec_).
You also might find this section of the Linux kernel documentation
useful: (access this in the Linux kernel source code)
......@@ -60,18 +57,18 @@ To use this feature you will need to get the device tree compiler. This is
provided by U-Boot automatically. If you have a system version of dtc
(typically in the 'device-tree-compiler' package), it is currently not used.
If you want to build your own dtc, it is kept here:
If you want to build your own dtc, it is kept here::
git://git.kernel.org/pub/scm/utils/dtc/dtc.git
For example:
For example::
$ git clone git://git.kernel.org/pub/scm/utils/dtc/dtc.git
$ cd dtc
$ make
$ sudo make install
Then run the compiler (your version will vary):
Then run the compiler (your version will vary)::
$ dtc -v
Version: DTC 1.2.0-g2cb4b51f
......@@ -105,14 +102,14 @@ Failing that, you could write one from scratch yourself!
Configuration
-------------
Use:
Use::
#define CONFIG_DEFAULT_DEVICE_TREE "<name>"
#define CONFIG_DEFAULT_DEVICE_TREE "<name>"
to set the filename of the device tree source. Then put your device tree
file into
file into::
board/<vendor>/dts/<name>.dts
board/<vendor>/dts/<name>.dts
This should include your CPU or SOC's device tree file, placed in
arch/<arch>/dts, and then make any adjustments required.
......@@ -123,9 +120,9 @@ and development only and is not recommended for production devices.
If CONFIG_OF_SEPARATE is defined, then it will be built and placed in
a u-boot.dtb file alongside u-boot-nodtb.bin. A common approach is then to
join the two:
join the two::
cat u-boot-nodtb.bin u-boot.dtb >image.bin
cat u-boot-nodtb.bin u-boot.dtb >image.bin
and then flash image.bin onto your board. Note that U-Boot creates
u-boot-dtb.bin which does the above step for you also. Resulting
......@@ -144,9 +141,9 @@ specify the file to read.
You cannot use more than one of these options at the same time.
To use a device tree file that you have compiled yourself, pass
EXT_DTB=<filename> to 'make', as in:
EXT_DTB=<filename> to 'make', as in::
make EXT_DTB=boot/am335x-boneblack-pubkey.dtb
make EXT_DTB=boot/am335x-boneblack-pubkey.dtb
Then U-Boot will copy that file to u-boot.dtb, put it in the .img file
if used, and u-boot-dtb.bin.
......@@ -162,16 +159,21 @@ variable will be set to the address of the newly relocated fdt blob.
It is read-only and cannot be changed. It can optionally be used to
control the boot process of Linux with bootm/bootz commands.
To use this, put something like this in your board header file:
To use this, put something like this in your board header file::
#define CONFIG_EXTRA_ENV_SETTINGS "fdtcontroladdr=10000\0"
#define CONFIG_EXTRA_ENV_SETTINGS "fdtcontroladdr=10000\0"
Build:
After board configuration is done, fdt supported u-boot can be build in two ways:
1) build the default dts which is defined from CONFIG_DEFAULT_DEVICE_TREE
After board configuration is done, fdt supported u-boot can be build in two
ways:
# build the default dts which is defined from CONFIG_DEFAULT_DEVICE_TREE::
$ make
2) build the user specified dts file
# build the user specified dts file::
$ make DEVICE_TREE=<dts-file-name>
......@@ -225,6 +227,4 @@ but can use the fdt to specific the UART clock, peripheral address, etc.
In very broad terms, the CONFIG options in general control *what* driver
files are pulled in, and the fdt controls *how* those files work.
--
Simon Glass <sjg@chromium.org>
1-Sep-11
.. _dtspec: https://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf
.. SPDX-License-Identifier: GPL-2.0+
Devicetree in U-Boot
====================
The following holds information on how U-Boot makes use of devicetree for
build-time and runtime configuration.
.. toctree::
:maxdepth: 2
intro
control
.. SPDX-License-Identifier: GPL-2.0+
Devicetree Introduction
=======================
......@@ -11,6 +11,7 @@ Implementation
ci_testing
commands
devicetree/index
driver-model/index
global_data
logging
......
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