#
# Copyright (c) 2011 The Chromium OS Authors.
#
-# See file CREDITS for list of people who contributed to this
-# project.
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License as
-# published by the Free Software Foundatio; either version 2 of
-# the License, or (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
-# MA 02111-1307 USA
+# SPDX-License-Identifier: GPL-2.0+
#
Device Tree Control in U-Boot
generic source base.
To enable this feature, add CONFIG_OF_CONTROL to your board config file.
+It is currently supported on ARM, x86 and Microblaze - other architectures
+will need to add code to their arch/xxx/lib/board.c file to locate the
+FDT. Alternatively you can enable generic board support on your board
+(with CONFIG_SYS_GENERIC_BOARD) if this is available (as it is for
+PowerPC). For ARM, Tegra and Exynos5 have device trees available for
+common devices.
What is a Flat Device Tree?
* Bad configuration: 0
* Strange test result: 0
-You will also find a useful ftdump utility for decoding a binary file.
+You will also find a useful fdtdump utility for decoding a binary file, as
+well as fdtget/fdtput for reading and writing properties in a binary file.
Where do I get an fdt file for my board?
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. The name of this
-is CONFIG_ARCH_DEVICE_TREE.dts.
+arch/<arch>/dts, and then make any adjustments required.
If CONFIG_OF_EMBED is defined, then it will be picked up and built into
the U-Boot image (including u-boot.bin).
and then flash image.bin onto your board.
-You cannot use both of these options at the same time.
+If CONFIG_OF_HOSTFILE is defined, then it will be read from a file on
+startup. This is only useful for sandbox. Use the -d flag to U-Boot to
+specify the file to read.
+
+You cannot use more than one of these options at the same time.
If you wish to put the fdt at a different address in memory, you can
define the "fdtcontroladdr" environment variable. This is the hex
#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
+ $ make
+2) build the user specified dts file
+ $ make DEVICE_TREE=<dts-file-name>
+
Limitations
-----------