karo: tx6: prevent DTB from either being out of reach of kernel or overwritten during...

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

diff --git a/doc/README.fdt-control b/doc/README.fdt-control
index 5963f78e96117113f03ea86acb8911b987d078a1..e6d5ed0bb61d664b0c7938c0649262f545d36fad 100644 (file)
--- a/doc/README.fdt-control
+++ b/doc/README.fdt-control
@@ -1,23 +1,7 @@
 #
 # Copyright (c) 2011 The Chromium OS Authors.
 #
 #
 # 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
 #
 
 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.
 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?
 
 
 What is a Flat Device Tree?


@@ -76,11 +66,11 @@ Tools
 
 To use this feature you will need to get the device tree compiler here:
 
 
 To use this feature you will need to get the device tree compiler here:
 

-       git://jdl.com/software/dtc.git
+       git://git.kernel.org/pub/scm/utils/dtc/dtc.git

 
 For example:
 
 
 For example:
 

-       $ git clone git://jdl.com/software/dtc.git
+       $ git clone git://git.kernel.org/pub/scm/utils/dtc/dtc.git

        $ cd dtc
        $ make
        $ sudo make install
        $ cd dtc
        $ make
        $ sudo make install


@@ -99,7 +89,8 @@ Then run the compiler (your version will vary):
        *   Bad configuration:  0
        * Strange test result:  0
 
        *   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?
 
 
 Where do I get an fdt file for my board?


@@ -128,11 +119,11 @@ file into
        board/<vendor>/dts/<name>.dts
 
 This should include your CPU or SOC's device tree file, placed in
        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
 
 If CONFIG_OF_EMBED is defined, then it will be picked up and built into

-the U-Boot image (including u-boot.bin).
+the U-Boot image (including u-boot.bin). This is suitable for debugging
+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.bin. A common approach is then to
 
 If CONFIG_OF_SEPARATE is defined, then it will be built and placed in
 a u-boot.dtb file alongside u-boot.bin. A common approach is then to


@@ -140,7 +131,10 @@ join the two:
 
        cat u-boot.bin u-boot.dtb >image.bin
 
 
        cat u-boot.bin u-boot.dtb >image.bin
 

-and then flash image.bin onto your board.
+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. If you are using
+CONFIG_SPL_FRAMEWORK, then u-boot.img will be built to include the device
+tree binary.

 
 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
 
 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


@@ -148,6 +142,14 @@ specify the file to read.
 
 You cannot use more than one of these options at the same time.
 
 
 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:
+
+       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.
+

 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.
 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.


@@ -169,6 +171,22 @@ After board configuration is done, fdt supported u-boot can be build in two ways
     $ make DEVICE_TREE=<dts-file-name>
 
 
     $ make DEVICE_TREE=<dts-file-name>
 
 

+Configuration Options
+---------------------
+
+A number of run-time configuration options are provided in the /config node
+of the control device tree. You can access these using fdtdec_get_config_int(),
+fdtdec_get_config_bool() and fdtdec_get_config_string().
+
+Available options are:
+
+silent-console
+       If present and non-zero, the console is silenced by default on boot.
+
+no-keyboard
+       Tells U-Boot not to expect an attached keyboard with a VGA console
+
+

 Limitations
 -----------
 
 Limitations
 -----------