X-Git-Url: https://git.kernelconcepts.de/?p=karo-tx-uboot.git;a=blobdiff_plain;f=doc%2FREADME.fdt-control;h=e6d5ed0bb61d664b0c7938c0649262f545d36fad;hp=5963f78e96117113f03ea86acb8911b987d078a1;hb=c41681294fbba1c9438651b819b4db28c3ba8085;hpb=cac423a730d3506154744485af1bbc1cd3a1e6a8 diff --git a/doc/README.fdt-control b/doc/README.fdt-control index 5963f78e96..e6d5ed0bb6 100644 --- 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? @@ -76,11 +66,11 @@ Tools 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: - $ 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 @@ -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? @@ -128,11 +119,11 @@ file into board//dts/.dts This should include your CPU or SOC's device tree file, placed in -arch//dts, and then make any adjustments required. The name of this -is CONFIG_ARCH_DEVICE_TREE.dts. +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). +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 @@ -140,7 +131,10 @@ join the two: 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 @@ -148,6 +142,14 @@ 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= 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. @@ -169,6 +171,22 @@ After board configuration is done, fdt supported u-boot can be build in two ways $ make DEVICE_TREE= +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 -----------