Merge branch 'u-boot-imx/master' into 'u-boot-arm/master'

[karo-tx-uboot.git] / doc / README.fdt-control

diff --git a/doc/README.fdt-control b/doc/README.fdt-control
index 3f8bb5a670175088c0147e7d6d57cefc36c1a32d..86bae6816d8a34714da246bfcfae7561d8e25055 100644 (file)
--- a/doc/README.fdt-control
+++ b/doc/README.fdt-control
@@ -1,23 +1,7 @@
 #
 # 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
@@ -49,6 +33,12 @@ the features of each board in the device tree file, and have a single
 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?
@@ -99,7 +89,8 @@ Then run the compiler (your version will vary):
        *   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?
@@ -128,8 +119,7 @@ file into
        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).
@@ -142,7 +132,31 @@ join the two:
 
 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
+address of the fdt binary blob, and will override either of the options.
+Be aware that this environment variable is checked prior to relocation,
+when only the compiled-in environment is available. Therefore it is not
+possible to define this variable in the saved SPI/NAND flash
+environment, for example (it will be ignored).
+
+To use this, put something like this in your board header file:
+
+#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