diff options
| -rw-r--r-- | Makefile | 5 | ||||
| -rw-r--r-- | README | 11 | ||||
| -rw-r--r-- | config.mk | 1 | ||||
| -rw-r--r-- | doc/README.fdt-control | 172 | ||||
| -rw-r--r-- | dts/Makefile | 103 | ||||
| -rw-r--r-- | include/common.h | 1 |
6 files changed, 291 insertions, 2 deletions
@@ -229,6 +229,9 @@ endif ifeq ($(CPU),ixp) LIBS += arch/arm/cpu/ixp/npe/libnpe.o endif +ifeq ($(CONFIG_OF_EMBED),y) +LIBS += dts/libdts.o +endif LIBS += arch/$(ARCH)/lib/lib$(ARCH).o LIBS += fs/cramfs/libcramfs.o fs/fat/libfat.o fs/fdos/libfdos.o fs/jffs2/libjffs2.o \ fs/reiserfs/libreiserfs.o fs/ext2/libext2fs.o fs/yaffs2/libyaffs2.o \ @@ -879,6 +882,7 @@ clobber: clean @rm -f $(obj)u-boot.kwb @rm -f $(obj)u-boot.imx @rm -f $(obj)u-boot.ubl + @rm -f $(obj)u-boot.dtb @rm -f $(obj)tools/{env/crc32.c,inca-swap-bytes} @rm -f $(obj)arch/powerpc/cpu/mpc824x/bedbug_603e.c @rm -fr $(obj)include/asm/proc $(obj)include/asm/arch $(obj)include/asm @@ -886,6 +890,7 @@ clobber: clean @[ ! -d $(obj)nand_spl ] || find $(obj)nand_spl -name "*" -type l -print | xargs rm -f @[ ! -d $(obj)onenand_ipl ] || find $(obj)onenand_ipl -name "*" -type l -print | xargs rm -f @[ ! -d $(obj)mmc_spl ] || find $(obj)mmc_spl -name "*" -type l -print | xargs rm -f + @rm -f $(obj)dts/*.tmp mrproper \ distclean: clobber unconfig @@ -824,8 +824,15 @@ The following options need to be configured: experimental and only available on a few boards. The device tree is available in the global data as gd->fdt_blob. - U-Boot needs to get its device tree from somewhere. This will - be enabled in a future patch. + U-Boot needs to get its device tree from somewhere. At present + the only way is to embed it in the image with CONFIG_OF_EMBED. + + CONFIG_OF_EMBED + If this variable is defined, U-Boot will embed a device tree + binary in its image. This device tree file should be in the + board directory and called <soc>-<board>.dts. The binary file + is then picked up in board_init_f() and made available through + the global data structure as gd->blob. - Watchdog: CONFIG_WATCHDOG @@ -124,6 +124,7 @@ STRIP = $(CROSS_COMPILE)strip OBJCOPY = $(CROSS_COMPILE)objcopy OBJDUMP = $(CROSS_COMPILE)objdump RANLIB = $(CROSS_COMPILE)RANLIB +DTC = dtc ######################################################################### diff --git a/doc/README.fdt-control b/doc/README.fdt-control new file mode 100644 index 0000000..3f8bb5a --- /dev/null +++ b/doc/README.fdt-control @@ -0,0 +1,172 @@ +# +# 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 +# + +Device Tree Control in U-Boot +============================= + +This feature provides for run-time configuration of U-Boot via a flat +device tree (fdt). U-Boot configuration has traditionally been done +using CONFIG options in the board config file. This feature aims to +make it possible for a single U-Boot binary to support multiple boards, +with the exact configuration of each board controlled by a flat device +tree (fdt). This is the approach recently taken by the ARM Linux kernel +and has been used by PowerPC for some time. + +The fdt is a convenient vehicle for implementing run-time configuration +for three reasons. Firstly it is easy to use, being a simple text file. +It is extensible since it consists of nodes and properties in a nice +hierarchical format. + +Finally, there is already excellent infrastructure for the fdt: a +compiler checks the text file and converts it to a compact binary +format, and a library is already available in U-Boot (libfdt) for +handling this format. + +The dts directory contains a Makefile for building the device tree blob +and embedding it in your U-Boot image. This is useful since it allows +U-Boot to configure itself according to what it finds there. If you have +a number of similar boards with different peripherals, you can describe +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. + + +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 + +You also might find this section of the Linux kernel documentation +useful: (access this in the Linux kernel source code) + + Documentation/devicetree/booting-without-of.txt + +There is also a mailing list: + + http://lists.ozlabs.org/listinfo/devicetree-discuss + +In case you are wondering, OF stands for Open Firmware. + + +Tools +----- + +To use this feature you will need to get the device tree compiler here: + + git://jdl.com/software/dtc.git + +For example: + + $ git clone git://jdl.com/software/dtc.git + $ cd dtc + $ make + $ sudo make install + +Then run the compiler (your version will vary): + + $ dtc -v + Version: DTC 1.2.0-g2cb4b51f + $ make tests + $ cd tests + $ ./run_tests.sh + ********** TEST SUMMARY + * Total testcases: 1371 + * PASS: 1371 + * FAIL: 0 + * Bad configuration: 0 + * Strange test result: 0 + +You will also find a useful ftdump utility for decoding a binary file. + + +Where do I get an fdt file for my board? +---------------------------------------- + +You may find that the Linux kernel has a suitable file. Look in the +kernel source in arch/<arch>/boot/dts. + +If not you might find other boards with suitable files that you can +modify to your needs. Look in the board directories for files with a +.dts extension. + +Failing that, you could write one from scratch yourself! + + +Configuration +------------- + +Use: + +#define CONFIG_DEFAULT_DEVICE_TREE "<name>" + +to set the filename of the device tree source. Then put your device tree +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. + +If CONFIG_OF_EMBED is defined, then it will be picked up and built into +the U-Boot image (including u-boot.bin). + +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 +join the two: + + cat u-boot.bin u-boot.dtb >image.bin + +and then flash image.bin onto your board. + +You cannot use both of these options at the same time. + + +Limitations +----------- + +U-Boot is designed to build with a single architecture type and CPU +type. So for example it is not possible to build a single ARM binary +which runs on your AT91 and OMAP boards, relying on an fdt to configure +the various features. This is because you must select one of +the CPU families within arch/arm/cpu/arm926ejs (omap or at91) at build +time. Similarly you cannot build for multiple cpu types or +architectures. + +That said the complexity reduction by using fdt to support variants of +boards which use the same SOC / CPU can be substantial. + +It is important to understand that the fdt only selects options +available in the platform / drivers. It cannot add new drivers (yet). So +you must still have the CONFIG option to enable the driver. For example, +you need to define CONFIG_SYS_NS16550 to bring in the NS16550 driver, +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 diff --git a/dts/Makefile b/dts/Makefile new file mode 100644 index 0000000..5792afd --- /dev/null +++ b/dts/Makefile @@ -0,0 +1,103 @@ +# +# 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 +# + +# This Makefile builds the internal U-Boot fdt if CONFIG_OF_CONTROL is +# enabled. See doc/README.fdt-control for more details. + +include $(TOPDIR)/config.mk + +LIB = $(obj)libdts.o + +$(if $(CONFIG_DEFAULT_DEVICE_TREE),,\ +$(error Please define CONFIG_DEFAULT_DEVICE_TREE in your board header file)) +DEVICE_TREE = $(subst ",,$(CONFIG_DEFAULT_DEVICE_TREE)) + +$(if $(CONFIG_ARCH_DEVICE_TREE),,\ +$(error Your architecture does not have device tree support enabled. \ +Please define CONFIG_ARCH_DEVICE_TREE)) + +# We preprocess the device tree file provide a useful define +DTS_CPPFLAGS := -DARCH_CPU_DTS=\"../arch/$(ARCH)/dts/$(CONFIG_ARCH_DEVICE_TREE).dtsi\" + +all: $(obj).depend $(LIB) + +# Use a constant name for this so we can access it from C code. +# objcopy doesn't seem to allow us to set the symbol name independently of +# the filename. +DT_BIN := $(obj)dt.dtb + +$(DT_BIN): $(TOPDIR)/board/$(VENDOR)/dts/$(DEVICE_TREE).dts + cat $< | $(CPP) -P $(DTS_CPPFLAGS) - >$@.tmp + $(DTC) -R 4 -p 0x1000 -O dtb -o ${DT_BIN} $@.tmp + rm $@.tmp + +process_lds = \ + $(1) | sed -r -n 's/^OUTPUT_$(2)[ ("]*([^")]*).*/\1/p' + +# Run the compiler and get the link script from the linker +GET_LDS = $(CC) $(CFLAGS) $(LDFLAGS) -Wl,--verbose 2>&1 + +$(obj)dt.o: $(DT_BIN) + # We want the output format and arch. + # We also hope to win a prize for ugliest Makefile / shell interaction + # We look in the LDSCRIPT first. + # Then try the linker which should give us the answer. + # Then check it worked. + oformat=`$(call process_lds,cat $(LDSCRIPT),FORMAT)` ;\ + oarch=`$(call process_lds,cat $(LDSCRIPT),ARCH)` ;\ + \ + [ -z $${oformat} ] && \ + oformat=`$(call process_lds,$(GET_LDS),FORMAT)` ;\ + [ -z $${oarch} ] && \ + oarch=`$(call process_lds,$(GET_LDS),ARCH)` ;\ + \ + [ -z $${oformat} ] && \ + echo "Cannot read OUTPUT_FORMAT from lds file $(LDSCRIPT)" && \ + exit 1 || true ;\ + [ -z $${oarch} ] && \ + echo "Cannot read OUTPUT_ARCH from lds file $(LDSCRIPT)" && \ + exit 1 || true ;\ + \ + cd $(dir ${DT_BIN}) && \ + $(OBJCOPY) -I binary -O $${oformat} -B $${oarch} \ + $(notdir ${DT_BIN}) $@ + rm $(DT_BIN) + +OBJS-$(CONFIG_OF_EMBED) := dt.o + +COBJS := $(OBJS-y) + +OBJS := $(addprefix $(obj),$(COBJS)) + +binary: $(DT_BIN) + +$(LIB): $(OBJS) $(DTB) + $(call cmd_link_o_target, $(OBJS)) + +######################################################################### + +# defines $(obj).depend target +include $(SRCTREE)/rules.mk + +sinclude $(obj).depend + +######################################################################### diff --git a/include/common.h b/include/common.h index 825ab72..fb41d7a 100644 --- a/include/common.h +++ b/include/common.h @@ -276,6 +276,7 @@ int checkdram (void); int last_stage_init(void); extern ulong monitor_flash_len; int mac_read_from_eeprom(void); +extern u8 _binary_dt_dtb_start[]; /* embedded device tree blob */ /* common/flash.c */ void flash_perror (int); |