#

  # (C) Copyright 2000 - 2013

  # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  #

  # SPDX-License-Identifier:	GPL-2.0+

  #
  
  Summary:
  ========

  This directory contains the source code for U-Boot, a boot loader for

  Embedded boards based on PowerPC, ARM, MIPS and several other
  processors, which can be installed in a boot ROM and used to
  initialize and test the hardware or to download and run application
  code.

  
  The development of U-Boot is closely related to Linux: some parts of

  the source code originate in the Linux source tree, we have some
  header files in common, and special provision has been made to

  support booting of Linux images.
  
  Some attention has been paid to make this software easily
  configurable and extendable. For instance, all monitor commands are
  implemented with the same call interface, so that it's very easy to
  add new commands. Also, instead of permanently adding rarely used
  code (for instance hardware test utilities) to the monitor, you can
  load and run it dynamically.
  
  
  Status:
  =======
  
  In general, all boards for which a configuration option exists in the

  Makefile have been tested to some extent and can be considered

  "working". In fact, many of them are used in production systems.

  In case of problems see the CHANGELOG and CREDITS files to find out

  who contributed the specific port. The boards.cfg file lists board

  maintainers.

  Note: There is no CHANGELOG file in the actual U-Boot source tree;
  it can be created dynamically from the Git log using:
  
  	make CHANGELOG

  
  Where to get help:
  ==================

  In case you have questions about, problems with or contributions for
  U-Boot you should send a message to the U-Boot mailing list at

  <u-boot@lists.denx.de>. There is also an archive of previous traffic
  on the mailing list - please search the archive before asking FAQ's.
  Please see http://lists.denx.de/pipermail/u-boot and
  http://dir.gmane.org/gmane.comp.boot-loaders.u-boot

  Where to get source code:
  =========================
  
  The U-Boot source code is maintained in the git repository at
  git://www.denx.de/git/u-boot.git ; you can browse it online at
  http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
  
  The "snapshot" links on this page allow you to download tarballs of

  any version you might be interested in. Official releases are also

  available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
  directory.

  Pre-built (and tested) images are available from

  ftp://ftp.denx.de/pub/u-boot/images/

  Where we come from:
  ===================
  
  - start from 8xxrom sources

  - create PPCBoot project (http://sourceforge.net/projects/ppcboot)

  - clean up code
  - make it easier to add custom boards
  - make it possible to add other [PowerPC] CPUs
  - extend functions, especially:
    * Provide extended interface to Linux boot loader
    * S-Record download
    * network boot

    * PCMCIA / CompactFlash / ATA disk / SCSI ... boot

  - create ARMBoot project (http://sourceforge.net/projects/armboot)

  - add other CPU families (starting with ARM)

  - create U-Boot project (http://sourceforge.net/projects/u-boot)

  - current project page: see http://www.denx.de/wiki/U-Boot

  
  
  Names and Spelling:
  ===================
  
  The "official" name of this project is "Das U-Boot". The spelling
  "U-Boot" shall be used in all written text (documentation, comments
  in source files etc.). Example:
  
  	This is the README file for the U-Boot project.
  
  File names etc. shall be based on the string "u-boot". Examples:
  
  	include/asm-ppc/u-boot.h
  
  	#include <asm/u-boot.h>
  
  Variable names, preprocessor constants etc. shall be either based on
  the string "u_boot" or on "U_BOOT". Example:
  
  	U_BOOT_VERSION		u_boot_logo
  	IH_OS_U_BOOT		u_boot_hush_start

  Versioning:
  ===========

  Starting with the release in October 2008, the names of the releases
  were changed from numerical release numbers without deeper meaning
  into a time stamp based numbering. Regular releases are identified by
  names consisting of the calendar year and month of the release date.
  Additional fields (if present) indicate release candidates or bug fix
  releases in "stable" maintenance trees.
  
  Examples:

  	U-Boot v2009.11	    - Release November 2009

  	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
  	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release

  Directory Hierarchy:
  ====================

  /arch			Architecture specific files

    /arc			Files generic to ARC architecture
      /cpu		CPU specific files
        /arc700		Files specific to ARC 700 CPUs
      /lib		Architecture specific library files

    /arm			Files generic to ARM architecture
      /cpu		CPU specific files
        /arm720t		Files specific to ARM 720 CPUs
        /arm920t		Files specific to ARM 920 CPUs

  	/at91		Files specific to Atmel AT91RM9200 CPU

  	/imx		Files specific to Freescale MC9328 i.MX CPUs
  	/s3c24x0	Files specific to Samsung S3C24X0 CPUs

        /arm926ejs	Files specific to ARM 926 CPUs
        /arm1136		Files specific to ARM 1136 CPUs

        /pxa		Files specific to Intel XScale PXA CPUs

        /sa1100		Files specific to Intel StrongARM SA1100 CPUs
      /lib		Architecture specific library files
    /avr32		Files generic to AVR32 architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files
    /blackfin		Files generic to Analog Devices Blackfin architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files

    /m68k			Files generic to m68k architecture
      /cpu		CPU specific files
        /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
        /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
        /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
        /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
        /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
      /lib		Architecture specific library files
    /microblaze		Files generic to microblaze architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files
    /mips			Files generic to MIPS architecture
      /cpu		CPU specific files

        /mips32		Files specific to MIPS32 CPUs

        /mips64		Files specific to MIPS64 CPUs

      /lib		Architecture specific library files

    /nds32		Files generic to NDS32 architecture
      /cpu		CPU specific files
        /n1213		Files specific to Andes Technology N1213 CPUs
      /lib		Architecture specific library files

    /nios2		Files generic to Altera NIOS2 architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files

    /openrisc		Files generic to OpenRISC architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files

    /powerpc		Files generic to PowerPC architecture

      /cpu		CPU specific files
        /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
        /mpc5xx		Files specific to Freescale MPC5xx CPUs
        /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
        /mpc8xx		Files specific to Freescale MPC8xx CPUs

        /mpc824x		Files specific to Freescale MPC824x CPUs
        /mpc8260		Files specific to Freescale MPC8260 CPUs
        /mpc85xx		Files specific to Freescale MPC85xx CPUs
        /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
      /lib		Architecture specific library files
    /sh			Files generic to SH architecture
      /cpu		CPU specific files
        /sh2		Files specific to sh2 CPUs
        /sh3		Files specific to sh3 CPUs
        /sh4		Files specific to sh4 CPUs
      /lib		Architecture specific library files
    /sparc		Files generic to SPARC architecture
      /cpu		CPU specific files
        /leon2		Files specific to Gaisler LEON2 SPARC CPU
        /leon3		Files specific to Gaisler LEON3 SPARC CPU
      /lib		Architecture specific library files

    /x86			Files generic to x86 architecture
      /cpu		CPU specific files
      /lib		Architecture specific library files

  /api			Machine/arch independent API for external apps
  /board			Board dependent files
  /common			Misc architecture independent functions
  /disk			Code for disk drive partition handling
  /doc			Documentation (don't expect too much)
  /drivers		Commonly used device drivers

  /dts			Contains Makefile for building internal U-Boot fdt.

  /examples		Example code for standalone applications, etc.
  /fs			Filesystem code (cramfs, ext2, jffs2, etc.)
  /include		Header Files
  /lib			Files generic to all architectures
    /libfdt		Library files to support flattened device trees
    /lzma			Library files to support LZMA decompression
    /lzo			Library files to support LZO decompression
  /net			Networking code
  /post			Power On Self Test

  /spl			Secondary Program Loader framework

  /tools			Tools to build S-Record or U-Boot images, etc.

  Software Configuration:
  =======================
  
  Configuration is usually done using C preprocessor defines; the
  rationale behind that is to avoid dead code whenever possible.
  
  There are two classes of configuration variables:
  
  * Configuration _OPTIONS_:
    These are selectable by the user and have names beginning with
    "CONFIG_".
  
  * Configuration _SETTINGS_:
    These depend on the hardware etc. and should not be meddled with if
    you don't know what you're doing; they have names beginning with

    "CONFIG_SYS_".

  
  Later we will add a configuration tool - probably similar to or even
  identical to what's used for the Linux kernel. Right now, we have to
  do the configuration by hand, which means creating some symbolic
  links and editing some configuration files. We use the TQM8xxL boards
  as an example here.
  
  
  Selection of Processor Architecture and Board Type:
  ---------------------------------------------------
  
  For all supported boards there are ready-to-use default

  configurations available; just type "make <board_name>_defconfig".

  
  Example: For a TQM823L module type:
  
  	cd u-boot

  	make TQM823L_defconfig

  For the Cogent platform, you need to specify the CPU type as well;

  e.g. "make cogent_mpc8xx_defconfig". And also configure the cogent

  directory according to the instructions in cogent/README.

  Sandbox Environment:
  --------------------
  
  U-Boot can be built natively to run on a Linux host using the 'sandbox'
  board. This allows feature development which is not board- or architecture-
  specific to be undertaken on a native platform. The sandbox is also used to
  run some of U-Boot's tests.

  See board/sandbox/README.sandbox for more details.

  Configuration Options:
  ----------------------
  
  Configuration depends on the combination of board and CPU type; all
  such information is kept in a configuration file
  "include/configs/<board_name>.h".
  
  Example: For a TQM823L module, all configuration settings are in
  "include/configs/TQM823L.h".

  Many of the options are named exactly as the corresponding Linux
  kernel configuration options. The intention is to make it easier to
  build a config tool - later.

  The following options need to be configured:

  - CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
  
  - Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.

  
  - CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)

  		Define exactly one, e.g. CONFIG_ATSTK1002

  
  - CPU Module Type: (if CONFIG_COGENT is defined)
  		Define exactly one of
  		CONFIG_CMA286_60_OLD
  --- FIXME --- not tested yet:
  		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
  		CONFIG_CMA287_23, CONFIG_CMA287_50
  
  - Motherboard Type: (if CONFIG_COGENT is defined)
  		Define exactly one of
  		CONFIG_CMA101, CONFIG_CMA102
  
  - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
  		Define one or more of
  		CONFIG_CMA302
  
  - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
  		Define one or more of
  		CONFIG_LCD_HEARTBEAT	- update a character position on

  					  the LCD display every second with

  					  a "rotator" |\-/|\-/

  - Marvell Family Member
  		CONFIG_SYS_MVFS		- define it if you want to enable
  					  multiple fs option at one time
  					  for marvell soc family

  - MPC824X Family Member (if CONFIG_MPC824X is defined)

  		Define exactly one of
  		CONFIG_MPC8240, CONFIG_MPC8245

  - 8xx CPU Options: (if using an MPC8xx CPU)

  		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
  					  get_gclk_freq() cannot work

  					  e.g. if there is no 32KHz
  					  reference PIT/RTC clock

  		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
  					  or XTAL/EXTAL)

  - 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):

  		CONFIG_SYS_8xx_CPUCLK_MIN
  		CONFIG_SYS_8xx_CPUCLK_MAX

  		CONFIG_8xx_CPUCLK_DEFAULT

  			See doc/README.MPC866

  		CONFIG_SYS_MEASURE_CPUCLK

  		Define this to measure the actual CPU clock instead
  		of relying on the correctness of the configured
  		values. Mostly useful for board bringup to make sure
  		the PLL is locked at the intended frequency. Note
  		that this requires a (stable) reference clock (32 kHz

  		RTC clock or CONFIG_SYS_8XX_XIN)

  		CONFIG_SYS_DELAYED_ICACHE
  
  		Define this option if you want to enable the
  		ICache only when Code runs from RAM.

  - 85xx CPU Options:

  		CONFIG_SYS_PPC64
  
  		Specifies that the core is a 64-bit PowerPC implementation (implements
  		the "64" category of the Power ISA). This is necessary for ePAPR
  		compliance, among other possible reasons.

  		CONFIG_SYS_FSL_TBCLK_DIV
  
  		Defines the core time base clock divider ratio compared to the
  		system clock.  On most PQ3 devices this is 8, on newer QorIQ
  		devices it can be 16 or 32.  The ratio varies from SoC to Soc.

  		CONFIG_SYS_FSL_PCIE_COMPAT
  
  		Defines the string to utilize when trying to match PCIe device
  		tree nodes for the given platform.

  		CONFIG_SYS_PPC_E500_DEBUG_TLB
  
  		Enables a temporary TLB entry to be used during boot to work
  		around limitations in e500v1 and e500v2 external debugger
  		support. This reduces the portions of the boot code where
  		breakpoints and single stepping do not work.  The value of this
  		symbol should be set to the TLB1 entry to be used for this
  		purpose.

  		CONFIG_SYS_FSL_ERRATUM_A004510
  
  		Enables a workaround for erratum A004510.  If set,
  		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
  		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
  
  		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
  		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
  
  		Defines one or two SoC revisions (low 8 bits of SVR)
  		for which the A004510 workaround should be applied.
  
  		The rest of SVR is either not relevant to the decision
  		of whether the erratum is present (e.g. p2040 versus
  		p2041) or is implied by the build target, which controls
  		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
  
  		See Freescale App Note 4493 for more information about
  		this erratum.

  		CONFIG_A003399_NOR_WORKAROUND
  		Enables a workaround for IFC erratum A003399. It is only
  		requred during NOR boot.

  		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
  
  		This is the value to write into CCSR offset 0x18600
  		according to the A004510 workaround.

  		CONFIG_SYS_FSL_DSP_DDR_ADDR
  		This value denotes start offset of DDR memory which is
  		connected exclusively to the DSP cores.

  		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
  		This value denotes start offset of M2 memory
  		which is directly connected to the DSP core.

  		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
  		This value denotes start offset of M3 memory which is directly
  		connected to the DSP core.

  		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
  		This value denotes start offset of DSP CCSR space.

  		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
  		Single Source Clock is clocking mode present in some of FSL SoC's.
  		In this mode, a single differential clock is used to supply
  		clocks to the sysclock, ddrclock and usbclock.

  		CONFIG_SYS_CPC_REINIT_F
  		This CONFIG is defined when the CPC is configured as SRAM at the
  		time of U-boot entry and is required to be re-initialized.

  		CONFIG_DEEP_SLEEP
  		Inidcates this SoC supports deep sleep feature. If deep sleep is
  		supported, core will start to execute uboot when wakes up.

  - Generic CPU options:

  		CONFIG_SYS_GENERIC_GLOBAL_DATA
  		Defines global data is initialized in generic board board_init_f().
  		If this macro is defined, global data is created and cleared in
  		generic board board_init_f(). Without this macro, architecture/board
  		should initialize global data before calling board_init_f().

  		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
  
  		Defines the endianess of the CPU. Implementation of those
  		values is arch specific.

  		CONFIG_SYS_FSL_DDR
  		Freescale DDR driver in use. This type of DDR controller is
  		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
  		SoCs.
  
  		CONFIG_SYS_FSL_DDR_ADDR
  		Freescale DDR memory-mapped register base.
  
  		CONFIG_SYS_FSL_DDR_EMU
  		Specify emulator support for DDR. Some DDR features such as
  		deskew training are not available.
  
  		CONFIG_SYS_FSL_DDRC_GEN1
  		Freescale DDR1 controller.
  
  		CONFIG_SYS_FSL_DDRC_GEN2
  		Freescale DDR2 controller.
  
  		CONFIG_SYS_FSL_DDRC_GEN3
  		Freescale DDR3 controller.

  		CONFIG_SYS_FSL_DDRC_GEN4
  		Freescale DDR4 controller.

  		CONFIG_SYS_FSL_DDRC_ARM_GEN3
  		Freescale DDR3 controller for ARM-based SoCs.

  		CONFIG_SYS_FSL_DDR1
  		Board config to use DDR1. It can be enabled for SoCs with
  		Freescale DDR1 or DDR2 controllers, depending on the board
  		implemetation.
  
  		CONFIG_SYS_FSL_DDR2
  		Board config to use DDR2. It can be eanbeld for SoCs with
  		Freescale DDR2 or DDR3 controllers, depending on the board
  		implementation.
  
  		CONFIG_SYS_FSL_DDR3
  		Board config to use DDR3. It can be enabled for SoCs with

  		Freescale DDR3 or DDR3L controllers.
  
  		CONFIG_SYS_FSL_DDR3L
  		Board config to use DDR3L. It can be enabled for SoCs with
  		DDR3L controllers.
  
  		CONFIG_SYS_FSL_DDR4
  		Board config to use DDR4. It can be enabled for SoCs with
  		DDR4 controllers.

  		CONFIG_SYS_FSL_IFC_BE
  		Defines the IFC controller register space as Big Endian
  
  		CONFIG_SYS_FSL_IFC_LE
  		Defines the IFC controller register space as Little Endian

  		CONFIG_SYS_FSL_PBL_PBI
  		It enables addition of RCW (Power on reset configuration) in built image.
  		Please refer doc/README.pblimage for more details
  
  		CONFIG_SYS_FSL_PBL_RCW
  		It adds PBI(pre-boot instructions) commands in u-boot build image.
  		PBI commands can be used to configure SoC before it starts the execution.
  		Please refer doc/README.pblimage for more details

  		CONFIG_SPL_FSL_PBL
  		It adds a target to create boot binary having SPL binary in PBI format
  		concatenated with u-boot binary.

  		CONFIG_SYS_FSL_DDR_BE
  		Defines the DDR controller register space as Big Endian
  
  		CONFIG_SYS_FSL_DDR_LE
  		Defines the DDR controller register space as Little Endian

  		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
  		Physical address from the view of DDR controllers. It is the
  		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
  		it could be different for ARM SoCs.

  		CONFIG_SYS_FSL_DDR_INTLV_256B
  		DDR controller interleaving on 256-byte. This is a special
  		interleaving mode, handled by Dickens for Freescale layerscape
  		SoCs with ARM core.

  		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
  		Number of controllers used as main memory.
  
  		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
  		Number of controllers used for other than main memory.

  		CONFIG_SYS_FSL_SEC_BE
  		Defines the SEC controller register space as Big Endian
  
  		CONFIG_SYS_FSL_SEC_LE
  		Defines the SEC controller register space as Little Endian

  - Intel Monahans options:

  		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO

  
  		Defines the Monahans run mode to oscillator
  		ratio. Valid values are 8, 16, 24, 31. The core
  		frequency is this value multiplied by 13 MHz.

  		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO

  		Defines the Monahans turbo mode to oscillator
  		ratio. Valid values are 1 (default if undefined) and

  		2. The core frequency as calculated above is multiplied

  		by this value.

  - MIPS CPU options:
  		CONFIG_SYS_INIT_SP_OFFSET
  
  		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
  		pointer. This is needed for the temporary stack before
  		relocation.
  
  		CONFIG_SYS_MIPS_CACHE_MODE
  
  		Cache operation mode for the MIPS CPU.
  		See also arch/mips/include/asm/mipsregs.h.
  		Possible values are:
  			CONF_CM_CACHABLE_NO_WA
  			CONF_CM_CACHABLE_WA
  			CONF_CM_UNCACHED
  			CONF_CM_CACHABLE_NONCOHERENT
  			CONF_CM_CACHABLE_CE
  			CONF_CM_CACHABLE_COW
  			CONF_CM_CACHABLE_CUW
  			CONF_CM_CACHABLE_ACCELERATED
  
  		CONFIG_SYS_XWAY_EBU_BOOTCFG
  
  		Special option for Lantiq XWAY SoCs for booting from NOR flash.
  		See also arch/mips/cpu/mips32/start.S.
  
  		CONFIG_XWAY_SWAP_BYTES
  
  		Enable compilation of tools/xway-swap-bytes needed for Lantiq
  		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
  		be swapped if a flash programmer is used.

  - ARM options:
  		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
  
  		Select high exception vectors of the ARM core, e.g., do not
  		clear the V bit of the c1 register of CP15.

  		CONFIG_SYS_THUMB_BUILD
  
  		Use this flag to build U-Boot using the Thumb instruction
  		set for ARM architectures. Thumb instruction set provides
  		better code density. For ARM architectures that support
  		Thumb2 this flag will result in Thumb2 code generated by
  		GCC.

  		CONFIG_ARM_ERRATA_716044

  		CONFIG_ARM_ERRATA_742230
  		CONFIG_ARM_ERRATA_743622
  		CONFIG_ARM_ERRATA_751472

  		CONFIG_ARM_ERRATA_794072

  		CONFIG_ARM_ERRATA_761320

  
  		If set, the workarounds for these ARM errata are applied early
  		during U-Boot startup. Note that these options force the
  		workarounds to be applied; no CPU-type/version detection
  		exists, unlike the similar options in the Linux kernel. Do not
  		set these options unless they apply!

  - Driver Model
  		Driver model is a new framework for devices in U-Boot
  		introduced in early 2014. U-Boot is being progressively
  		moved over to this. It offers a consistent device structure,
  		supports grouping devices into classes and has built-in
  		handling of platform data and device tree.
  
  		To enable transition to driver model in a relatively
  		painful fashion, each subsystem can be independently
  		switched between the legacy/ad-hoc approach and the new
  		driver model using the options below. Also, many uclass
  		interfaces include compatibility features which may be
  		removed once the conversion of that subsystem is complete.
  		As a result, the API provided by the subsystem may in fact
  		not change with driver model.
  
  		See doc/driver-model/README.txt for more information.
  
  		CONFIG_DM
  
  		Enable driver model. This brings in the core support,
  		including scanning of platform data on start-up. If
  		CONFIG_OF_CONTROL is enabled, the device tree will be
  		scanned also when available.
  
  		CONFIG_CMD_DM
  
  		Enable driver model test commands. These allow you to print
  		out the driver model tree and the uclasses.
  
  		CONFIG_DM_DEMO
  
  		Enable some demo devices and the 'demo' command. These are
  		really only useful for playing around while trying to
  		understand driver model in sandbox.
  
  		CONFIG_SPL_DM
  
  		Enable driver model in SPL. You will need to provide a
  		suitable malloc() implementation. If you are not using the
  		full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
  		consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
  		must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
  		In most cases driver model will only allocate a few uclasses
  		and devices in SPL, so 1KB should be enable. See
  		CONFIG_SYS_MALLOC_F_LEN for more details on how to enable
  		it.
  
  		CONFIG_DM_SERIAL
  
  		Enable driver model for serial. This replaces
  		drivers/serial/serial.c with the serial uclass, which
  		implements serial_putc() etc. The uclass interface is
  		defined in include/serial.h.
  
  		CONFIG_DM_GPIO
  
  		Enable driver model for GPIO access. The standard GPIO
  		interface (gpio_get_value(), etc.) is then implemented by
  		the GPIO uclass. Drivers provide methods to query the
  		particular GPIOs that they provide. The uclass interface
  		is defined in include/asm-generic/gpio.h.
  
  		CONFIG_DM_SPI
  
  		Enable driver model for SPI. The SPI slave interface
  		(spi_setup_slave(), spi_xfer(), etc.) is then implemented by
  		the SPI uclass. Drivers provide methods to access the SPI
  		buses that they control. The uclass interface is defined in
  		include/spi.h. The existing spi_slave structure is attached
  		as 'parent data' to every slave on each bus. Slaves
  		typically use driver-private data instead of extending the
  		spi_slave structure.
  
  		CONFIG_DM_SPI_FLASH
  
  		Enable driver model for SPI flash. This SPI flash interface
  		(spi_flash_probe(), spi_flash_write(), etc.) is then
  		implemented by the SPI flash uclass. There is one standard
  		SPI flash driver which knows how to probe most chips
  		supported by U-Boot. The uclass interface is defined in
  		include/spi_flash.h, but is currently fully compatible
  		with the old interface to avoid confusion and duplication
  		during the transition parent. SPI and SPI flash must be
  		enabled together (it is not possible to use driver model
  		for one and not the other).
  
  		CONFIG_DM_CROS_EC
  
  		Enable driver model for the Chrome OS EC interface. This
  		allows the cros_ec SPI driver to operate with CONFIG_DM_SPI
  		but otherwise makes few changes. Since cros_ec also supports
  		I2C and LPC (which don't support driver model yet), a full
  		conversion is not yet possible.
  
  
  		** Code size options: The following options are enabled by
  		default except in SPL. Enable them explicitly to get these
  		features in SPL.
  
  		CONFIG_DM_WARN
  
  		Enable the dm_warn() function. This can use up quite a bit
  		of space for its strings.
  
  		CONFIG_DM_STDIO
  
  		Enable registering a serial device with the stdio library.
  
  		CONFIG_DM_DEVICE_REMOVE
  
  		Enable removing of devices.

  - Linux Kernel Interface:

  		CONFIG_CLOCKS_IN_MHZ
  
  		U-Boot stores all clock information in Hz
  		internally. For binary compatibility with older Linux
  		kernels (which expect the clocks passed in the
  		bd_info data to be in MHz) the environment variable
  		"clocks_in_mhz" can be defined so that U-Boot
  		converts clock data to MHZ before passing it to the
  		Linux kernel.

  		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of

  		"clocks_in_mhz=1" is automatically included in the

  		default environment.

  		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]

  		When transferring memsize parameter to linux, some versions

  		expect it to be in bytes, others in MB.
  		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.

  		CONFIG_OF_LIBFDT

  
  		New kernel versions are expecting firmware settings to be

  		passed using flattened device trees (based on open firmware
  		concepts).
  
  		CONFIG_OF_LIBFDT
  		 * New libfdt-based support
  		 * Adds the "fdt" command

  		 * The bootm command automatically updates the fdt

  		OF_CPU - The proper name of the cpus node (only required for
  			MPC512X and MPC5xxx based boards).
  		OF_SOC - The proper name of the soc node (only required for
  			MPC512X and MPC5xxx based boards).

  		OF_TBCLK - The timebase frequency.

  		OF_STDOUT_PATH - The path to the console device

  		boards with QUICC Engines require OF_QE to set UCC MAC
  		addresses

  		CONFIG_OF_BOARD_SETUP
  
  		Board code has addition modification that it wants to make
  		to the flat device tree before handing it off to the kernel

  		CONFIG_OF_BOOT_CPU

  		This define fills in the correct boot CPU in the boot

  		param header, the default value is zero if undefined.

  		CONFIG_OF_IDE_FIXUP
  
  		U-Boot can detect if an IDE device is present or not.
  		If not, and this new config option is activated, U-Boot
  		removes the ATA node from the DTS before booting Linux,
  		so the Linux IDE driver does not probe the device and
  		crash. This is needed for buggy hardware (uc101) where
  		no pull down resistor is connected to the signal IDE5V_DD7.

  		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
  
  		This setting is mandatory for all boards that have only one
  		machine type and must be used to specify the machine type
  		number as it appears in the ARM machine registry
  		(see http://www.arm.linux.org.uk/developer/machines/).
  		Only boards that have multiple machine types supported
  		in a single configuration file and the machine type is
  		runtime discoverable, do not have to use this setting.

  - vxWorks boot parameters:
  
  		bootvx constructs a valid bootline using the following
  		environments variables: bootfile, ipaddr, serverip, hostname.
  		It loads the vxWorks image pointed bootfile.
  
  		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
  		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
  		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
  		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
  
  		CONFIG_SYS_VXWORKS_ADD_PARAMS
  
  		Add it at the end of the bootline. E.g "u=username pw=secret"
  
  		Note: If a "bootargs" environment is defined, it will overwride
  		the defaults discussed just above.

  - Cache Configuration:
  		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
  		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
  		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot

  - Cache Configuration for ARM:
  		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
  				      controller
  		CONFIG_SYS_PL310_BASE - Physical base address of PL310
  					controller register space

  - Serial Ports:

  		CONFIG_PL010_SERIAL

  
  		Define this if you want support for Amba PrimeCell PL010 UARTs.

  		CONFIG_PL011_SERIAL

  
  		Define this if you want support for Amba PrimeCell PL011 UARTs.
  
  		CONFIG_PL011_CLOCK
  
  		If you have Amba PrimeCell PL011 UARTs, set this variable to
  		the clock speed of the UARTs.
  
  		CONFIG_PL01x_PORTS
  
  		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
  		define this to a list of base addresses for each (supported)
  		port. See e.g. include/configs/versatile.h

  		CONFIG_PL011_SERIAL_RLCR
  
  		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
  		have separate receive and transmit line control registers.  Set
  		this variable to initialize the extra register.
  
  		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
  
  		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
  		boot loader that has already initialized the UART.  Define this
  		variable to flush the UART at init time.

  		CONFIG_SERIAL_HW_FLOW_CONTROL
  
  		Define this variable to enable hw flow control in serial driver.
  		Current user of this option is drivers/serial/nsl16550.c driver

  - Console Interface:

  		Depending on board, define exactly one serial port
  		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
  		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
  		console by defining CONFIG_8xx_CONS_NONE

  
  		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
  		port routines must be defined elsewhere
  		(i.e. serial_init(), serial_getc(), ...)
  
  		CONFIG_CFB_CONSOLE
  		Enables console device for a color framebuffer. Needs following

  		defines (cf. smiLynxEM, i8042)

  			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
  						(default big endian)
  			VIDEO_HW_RECTFILL	graphic chip supports
  						rectangle fill
  						(cf. smiLynxEM)
  			VIDEO_HW_BITBLT		graphic chip supports
  						bit-blit (cf. smiLynxEM)
  			VIDEO_VISIBLE_COLS	visible pixel columns
  						(cols=pitch)

  			VIDEO_VISIBLE_ROWS	visible pixel rows
  			VIDEO_PIXEL_SIZE	bytes per pixel

  			VIDEO_DATA_FORMAT	graphic data format
  						(0-5, cf. cfb_console.c)

  			VIDEO_FB_ADRS		framebuffer address

  			VIDEO_KBD_INIT_FCT	keyboard int fct
  						(i.e. i8042_kbd_init())
  			VIDEO_TSTC_FCT		test char fct
  						(i.e. i8042_tstc)
  			VIDEO_GETC_FCT		get char fct
  						(i.e. i8042_getc)
  			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
  						(requires blink timer
  						cf. i8042.c)

  			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)

  			CONFIG_CONSOLE_TIME	display time/date info in
  						upper right corner

  						(requires CONFIG_CMD_DATE)

  			CONFIG_VIDEO_LOGO	display Linux logo in
  						upper left corner

  			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
  						linux_logo.h for logo.
  						Requires CONFIG_VIDEO_LOGO

  			CONFIG_CONSOLE_EXTRA_INFO

  						additional board info beside

  						the logo

  		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
  		a limited number of ANSI escape sequences (cursor control,
  		erase functions and limited graphics rendition control).

  		When CONFIG_CFB_CONSOLE is defined, video console is
  		default i/o. Serial console can be forced with
  		environment 'console=serial'.

  		When CONFIG_SILENT_CONSOLE is defined, all console
  		messages (by U-Boot and Linux!) can be silenced with
  		the "silent" environment variable. See
  		doc/README.silent for more information.

  		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
  			is 0x00.
  		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
  			is 0xa0.

  - Console Baudrate:
  		CONFIG_BAUDRATE - in bps
  		Select one of the baudrates listed in

  		CONFIG_SYS_BAUDRATE_TABLE, see below.
  		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale

  - Console Rx buffer length
  		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
  		the maximum receive buffer length for the SMC.

  		This option is actual only for 82xx and 8xx possible.

  		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
  		must be defined, to setup the maximum idle timeout for
  		the SMC.

  - Pre-Console Buffer:

  		Prior to the console being initialised (i.e. serial UART
  		initialised etc) all console output is silently discarded.
  		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
  		buffer any console messages prior to the console being
  		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
  		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
  		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ

  		bytes are output before the console is initialised, the

  		earlier bytes are discarded.
  
  		'Sane' compilers will generate smaller code if
  		CONFIG_PRE_CON_BUF_SZ is a power of 2

  - Safe printf() functions
  		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
  		the printf() functions. These are defined in
  		include/vsprintf.h and include snprintf(), vsnprintf() and
  		so on. Code size increase is approximately 300-500 bytes.
  		If this option is not given then these functions will
  		silently discard their buffer size argument - this means
  		you are not getting any overflow checking in this case.

  - Boot Delay:	CONFIG_BOOTDELAY - in seconds
  		Delay before automatically booting the default image;
  		set to -1 to disable autoboot.

  		set to -2 to autoboot with no delay and not check for abort
  		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).

  
  		See doc/README.autoboot for these options that
  		work with CONFIG_BOOTDELAY. None are required.
  		CONFIG_BOOT_RETRY_TIME
  		CONFIG_BOOT_RETRY_MIN
  		CONFIG_AUTOBOOT_KEYED
  		CONFIG_AUTOBOOT_PROMPT
  		CONFIG_AUTOBOOT_DELAY_STR
  		CONFIG_AUTOBOOT_STOP_STR
  		CONFIG_AUTOBOOT_DELAY_STR2
  		CONFIG_AUTOBOOT_STOP_STR2
  		CONFIG_ZERO_BOOTDELAY_CHECK
  		CONFIG_RESET_TO_RETRY
  
  - Autoboot Command:
  		CONFIG_BOOTCOMMAND
  		Only needed when CONFIG_BOOTDELAY is enabled;
  		define a command string that is automatically executed
  		when no character is read on the console interface
  		within "Boot Delay" after reset.
  
  		CONFIG_BOOTARGS

  		This can be used to pass arguments to the bootm
  		command. The value of CONFIG_BOOTARGS goes into the
  		environment value "bootargs".

  
  		CONFIG_RAMBOOT and CONFIG_NFSBOOT

  		The value of these goes into the environment as
  		"ramboot" and "nfsboot" respectively, and can be used
  		as a convenience, when switching between booting from

  		RAM and NFS.

  - Bootcount:
  		CONFIG_BOOTCOUNT_LIMIT
  		Implements a mechanism for detecting a repeating reboot
  		cycle, see:
  		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
  
  		CONFIG_BOOTCOUNT_ENV
  		If no softreset save registers are found on the hardware
  		"bootcount" is stored in the environment. To prevent a
  		saveenv on all reboots, the environment variable
  		"upgrade_available" is used. If "upgrade_available" is
  		0, "bootcount" is always 0, if "upgrade_available" is
  		1 "bootcount" is incremented in the environment.
  		So the Userspace Applikation must set the "upgrade_available"
  		and "bootcount" variable to 0, if a boot was successfully.

  - Pre-Boot Commands:
  		CONFIG_PREBOOT
  
  		When this option is #defined, the existence of the
  		environment variable "preboot" will be checked
  		immediately before starting the CONFIG_BOOTDELAY
  		countdown and/or running the auto-boot command resp.
  		entering interactive mode.
  
  		This feature is especially useful when "preboot" is
  		automatically generated or modified. For an example
  		see the LWMON board specific code: here "preboot" is
  		modified when the user holds down a certain
  		combination of keys on the (special) keyboard when
  		booting the systems
  
  - Serial Download Echo Mode:
  		CONFIG_LOADS_ECHO
  		If defined to 1, all characters received during a
  		serial download (using the "loads" command) are
  		echoed back. This might be needed by some terminal
  		emulations (like "cu"), but may as well just take
  		time on others. This setting #define's the initial
  		value of the "loads_echo" environment variable.

  - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)

  		CONFIG_KGDB_BAUDRATE
  		Select one of the baudrates listed in

  		CONFIG_SYS_BAUDRATE_TABLE, see below.

  
  - Monitor Functions:

  		Monitor commands can be included or excluded
  		from the build by using the #include files

  		<config_cmd_all.h> and #undef'ing unwanted
  		commands, or using <config_cmd_default.h>

  		and augmenting with additional #define's
  		for wanted commands.
  
  		The default command configuration includes all commands
  		except those marked below with a "*".

  		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt

  		CONFIG_CMD_ASKENV	* ask for env variable

  		CONFIG_CMD_BDI		  bdinfo
  		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
  		CONFIG_CMD_BMP		* BMP support
  		CONFIG_CMD_BSP		* Board specific commands
  		CONFIG_CMD_BOOTD	  bootd

  		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support

  		CONFIG_CMD_CACHE	* icache, dcache

  		CONFIG_CMD_CLK   	* clock command support

  		CONFIG_CMD_CONSOLE	  coninfo

  		CONFIG_CMD_CRC32	* crc32

  		CONFIG_CMD_DATE		* support for RTC, date/time...
  		CONFIG_CMD_DHCP		* DHCP support
  		CONFIG_CMD_DIAG		* Diagnostics

  		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
  		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
  		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
  		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command

  		CONFIG_CMD_DTT		* Digital Therm and Thermostat
  		CONFIG_CMD_ECHO		  echo arguments

  		CONFIG_CMD_EDITENV	  edit env variable

  		CONFIG_CMD_EEPROM	* EEPROM read/write support
  		CONFIG_CMD_ELF		* bootelf, bootvx

  		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks

  		CONFIG_CMD_ENV_FLAGS	* display details about env flags

  		CONFIG_CMD_ENV_EXISTS	* check existence of env variable

  		CONFIG_CMD_EXPORTENV	* export the environment

  		CONFIG_CMD_EXT2		* ext2 command support
  		CONFIG_CMD_EXT4		* ext4 command support

  		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
  					  that work for multiple fs types

  		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID

  		CONFIG_CMD_SAVEENV	  saveenv

  		CONFIG_CMD_FDC		* Floppy Disk Support

  		CONFIG_CMD_FAT		* FAT command support

  		CONFIG_CMD_FLASH	  flinfo, erase, protect
  		CONFIG_CMD_FPGA		  FPGA device initialization support

  		CONFIG_CMD_FUSE		* Device fuse support

  		CONFIG_CMD_GETTIME	* Get time since boot

  		CONFIG_CMD_GO		* the 'go' command (exec code)

  		CONFIG_CMD_GREPENV	* search environment

  		CONFIG_CMD_HASH		* calculate hash / digest

  		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
  		CONFIG_CMD_I2C		* I2C serial bus support
  		CONFIG_CMD_IDE		* IDE harddisk support
  		CONFIG_CMD_IMI		  iminfo

  		CONFIG_CMD_IMLS		  List all images found in NOR flash

  		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash

  		CONFIG_CMD_IMMAP	* IMMR dump support

  		CONFIG_CMD_IOTRACE	* I/O tracing for debugging

  		CONFIG_CMD_IMPORTENV	* import an environment

  		CONFIG_CMD_INI		* import data from an ini file into the env

  		CONFIG_CMD_IRQ		* irqinfo
  		CONFIG_CMD_ITEST	  Integer/string test of 2 values
  		CONFIG_CMD_JFFS2	* JFFS2 Support
  		CONFIG_CMD_KGDB		* kgdb

  		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)

  		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
  					  (169.254.*.*)

  		CONFIG_CMD_LOADB	  loadb
  		CONFIG_CMD_LOADS	  loads

  		CONFIG_CMD_MD5SUM	* print md5 message digest

  					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)

  		CONFIG_CMD_MEMINFO	* Display detailed memory information

  		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,

  					  loop, loopw

  		CONFIG_CMD_MEMTEST	* mtest

  		CONFIG_CMD_MISC		  Misc functions like sleep etc
  		CONFIG_CMD_MMC		* MMC memory mapped support
  		CONFIG_CMD_MII		* MII utility commands

  		CONFIG_CMD_MTDPARTS	* MTD partition support

  		CONFIG_CMD_NAND		* NAND support
  		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot

  		CONFIG_CMD_NFS		  NFS support

  		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands

  		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command

  		CONFIG_CMD_PCI		* pciinfo
  		CONFIG_CMD_PCMCIA		* PCMCIA support
  		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
  					  host
  		CONFIG_CMD_PORTIO	* Port I/O

  		CONFIG_CMD_READ		* Read raw data from partition

  		CONFIG_CMD_REGINFO	* Register dump
  		CONFIG_CMD_RUN		  run command in env variable

  		CONFIG_CMD_SANDBOX	* sb command to access sandbox features

  		CONFIG_CMD_SAVES	* save S record dump
  		CONFIG_CMD_SCSI		* SCSI Support
  		CONFIG_CMD_SDRAM	* print SDRAM configuration information
  					  (requires CONFIG_CMD_I2C)
  		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
  					  (4xx only)

  		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash

  		CONFIG_CMD_SHA1SUM	* print sha1 memory digest

  					  (requires CONFIG_CMD_MEMORY)

  		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x

  		CONFIG_CMD_SOURCE	  "source" command Support

  		CONFIG_CMD_SPI		* SPI serial bus support

  		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode

  		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)

  		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
  		CONFIG_CMD_TIMER	* access to the system tick timer

  		CONFIG_CMD_USB		* USB support

  		CONFIG_CMD_CDP		* Cisco Discover Protocol support

  		CONFIG_CMD_MFSL		* Microblaze FSL support

  		CONFIG_CMD_XIMG		  Load part of Multi Image

  		CONFIG_CMD_UUID		* Generate random UUID or GUID string

  
  		EXAMPLE: If you want all functions except of network
  		support you can write:

  		#include "config_cmd_all.h"
  		#undef CONFIG_CMD_NET

  	Other Commands:
  		fdt (flattened device tree) command: CONFIG_OF_LIBFDT

  
  	Note:	Don't enable the "icache" and "dcache" commands

  		(configuration option CONFIG_CMD_CACHE) unless you know

  		what you (and your U-Boot users) are doing. Data
  		cache cannot be enabled on systems like the 8xx or
  		8260 (where accesses to the IMMR region must be
  		uncached), and it cannot be disabled on all other
  		systems where we (mis-) use the data cache to hold an
  		initial stack and some data.

  
  
  		XXX - this list needs to get updated!

  - Regular expression support:
  		CONFIG_REGEX

  		If this variable is defined, U-Boot is linked against
  		the SLRE (Super Light Regular Expression) library,
  		which adds regex support to some commands, as for
  		example "env grep" and "setexpr".

  - Device tree:
  		CONFIG_OF_CONTROL
  		If this variable is defined, U-Boot will use a device tree
  		to configure its devices, instead of relying on statically
  		compiled #defines in the board file. This option is
  		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 can
  		be done using one of the two options below:

  
  		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.

  		CONFIG_OF_SEPARATE
  		If this variable is defined, U-Boot will build a device tree
  		binary. It will be called u-boot.dtb. Architecture-specific
  		code will locate it at run-time. Generally this works by:
  
  			cat u-boot.bin u-boot.dtb >image.bin
  
  		and in fact, U-Boot does this for you, creating a file called
  		u-boot-dtb.bin which is useful in the common case. You can
  		still use the individual files if you need something more
  		exotic.

  - Watchdog:
  		CONFIG_WATCHDOG
  		If this variable is defined, it enables watchdog

  		support for the SoC. There must be support in the SoC
  		specific code for a watchdog. For the 8xx and 8260
  		CPUs, the SIU Watchdog feature is enabled in the SYPCR
  		register.  When supported for a specific SoC is
  		available, then no further board specific code should
  		be needed to use it.
  
  		CONFIG_HW_WATCHDOG
  		When using a watchdog circuitry external to the used
  		SoC, then define this variable and provide board
  		specific code for the "hw_watchdog_reset" function.

  - U-Boot Version:
  		CONFIG_VERSION_VARIABLE
  		If this variable is defined, an environment variable
  		named "ver" is created by U-Boot showing the U-Boot
  		version as printed by the "version" command.

  		Any change to this variable will be reverted at the
  		next reset.

  - Real-Time Clock:

  		When CONFIG_CMD_DATE is selected, the type of the RTC

  		has to be selected, too. Define exactly one of the
  		following options:
  
  		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
  		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC

  		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC

  		CONFIG_RTC_MC146818	- use MC146818 RTC

  		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC

  		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC

  		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC

  		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC

  		CONFIG_RTC_DS164x	- use Dallas DS164x RTC

  		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC

  		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC

  		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337

  		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
  					  RV3029 RTC.

  		Note that if the RTC uses I2C, then the I2C interface
  		must also be configured. See I2C Support, below.

  - GPIO Support:
  		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO

  		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
  		chip-ngpio pairs that tell the PCA953X driver the number of
  		pins supported by a particular chip.

  		Note that if the GPIO device uses I2C, then the I2C interface
  		must also be configured. See I2C Support, below.

  - I/O tracing:
  		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
  		accesses and can checksum them or write a list of them out
  		to memory. See the 'iotrace' command for details. This is
  		useful for testing device drivers since it can confirm that
  		the driver behaves the same way before and after a code
  		change. Currently this is supported on sandbox and arm. To
  		add support for your architecture, add '#include <iotrace.h>'
  		to the bottom of arch/<arch>/include/asm/io.h and test.
  
  		Example output from the 'iotrace stats' command is below.
  		Note that if the trace buffer is exhausted, the checksum will
  		still continue to operate.
  
  			iotrace is enabled
  			Start:  10000000	(buffer start address)
  			Size:   00010000	(buffer size)
  			Offset: 00000120	(current buffer offset)
  			Output: 10000120	(start + offset)
  			Count:  00000018	(number of trace records)
  			CRC32:  9526fb66	(CRC32 of all trace records)

  - Timestamp Support:

  		When CONFIG_TIMESTAMP is selected, the timestamp
  		(date and time) of an image is printed by image
  		commands like bootm or iminfo. This option is

  		automatically enabled when you select CONFIG_CMD_DATE .

  - Partition Labels (disklabels) Supported:
  		Zero or more of the following:
  		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
  		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
  				       Intel architecture, USB sticks, etc.
  		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
  		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
  				       bootloader.  Note 2TB partition limit; see
  				       disk/part_efi.c
  		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.

  		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
  		CONFIG_CMD_SCSI) you must configure support for at

  		least one non-MTD partition type as well.

  
  - IDE Reset method:

  		CONFIG_IDE_RESET_ROUTINE - this is defined in several
  		board configurations files but used nowhere!

  		CONFIG_IDE_RESET - is this is defined, IDE Reset will
  		be performed by calling the function
  			ide_set_reset(int reset)
  		which has to be defined in a board specific file

  
  - ATAPI Support:
  		CONFIG_ATAPI
  
  		Set this to enable ATAPI support.

  - LBA48 Support
  		CONFIG_LBA48
  
  		Set this to enable support for disks larger than 137GB

  		Also look at CONFIG_SYS_64BIT_LBA.

  		Whithout these , LBA48 support uses 32bit variables and will 'only'
  		support disks up to 2.1TB.

  		CONFIG_SYS_64BIT_LBA:

  			When enabled, makes the IDE subsystem use 64bit sector addresses.
  			Default is 32bit.

  - SCSI Support:
  		At the moment only there is only support for the
  		SYM53C8XX SCSI controller; define
  		CONFIG_SCSI_SYM53C8XX to enable it.

  		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
  		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
  		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the

  		maximum numbers of LUNs, SCSI ID's and target
  		devices.

  		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)

  		The environment variable 'scsidevs' is set to the number of
  		SCSI devices found during the last scan.

  - NETWORK Support (PCI):

  		CONFIG_E1000

  		Support for Intel 8254x/8257x gigabit chips.
  
  		CONFIG_E1000_SPI
  		Utility code for direct access to the SPI bus on Intel 8257x.
  		This does not do anything useful unless you set at least one
  		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
  
  		CONFIG_E1000_SPI_GENERIC
  		Allow generic access to the SPI bus on the Intel 8257x, for
  		example with the "sspi" command.
  
  		CONFIG_CMD_E1000
  		Management command for E1000 devices.  When used on devices
  		with SPI support you can reprogram the EEPROM from U-Boot.

  		CONFIG_E1000_FALLBACK_MAC

  		default MAC for empty EEPROM after production.

  		CONFIG_EEPRO100
  		Support for Intel 82557/82559/82559ER chips.

  		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM

  		write routine for first time initialisation.
  
  		CONFIG_TULIP
  		Support for Digital 2114x chips.
  		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
  		modem chip initialisation (KS8761/QS6611).
  
  		CONFIG_NATSEMI
  		Support for National dp83815 chips.
  
  		CONFIG_NS8382X
  		Support for National dp8382[01] gigabit chips.

  - NETWORK Support (other):

  		CONFIG_DRIVER_AT91EMAC
  		Support for AT91RM9200 EMAC.
  
  			CONFIG_RMII
  			Define this to use reduced MII inteface
  
  			CONFIG_DRIVER_AT91EMAC_QUIET
  			If this defined, the driver is quiet.
  			The driver doen't show link status messages.

  		CONFIG_CALXEDA_XGMAC
  		Support for the Calxeda XGMAC device

  		CONFIG_LAN91C96

  		Support for SMSC's LAN91C96 chips.
  
  			CONFIG_LAN91C96_BASE
  			Define this to hold the physical address
  			of the LAN91C96's I/O space
  
  			CONFIG_LAN91C96_USE_32_BIT
  			Define this to enable 32 bit addressing

  		CONFIG_SMC91111

  		Support for SMSC's LAN91C111 chip
  
  			CONFIG_SMC91111_BASE
  			Define this to hold the physical address
  			of the device (I/O space)
  
  			CONFIG_SMC_USE_32_BIT
  			Define this if data bus is 32 bits
  
  			CONFIG_SMC_USE_IOFUNCS
  			Define this to use i/o functions instead of macros
  			(some hardware wont work with macros)

  		CONFIG_DRIVER_TI_EMAC
  		Support for davinci emac
  
  			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
  			Define this if you have more then 3 PHYs.

  		CONFIG_FTGMAC100
  		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
  
  			CONFIG_FTGMAC100_EGIGA
  			Define this to use GE link update with gigabit PHY.
  			Define this if FTGMAC100 is connected to gigabit PHY.
  			If your system has 10/100 PHY only, it might not occur
  			wrong behavior. Because PHY usually return timeout or
  			useless data when polling gigabit status and gigabit
  			control registers. This behavior won't affect the
  			correctnessof 10/100 link speed update.

  		CONFIG_SMC911X

  		Support for SMSC's LAN911x and LAN921x chips

  			CONFIG_SMC911X_BASE

  			Define this to hold the physical address
  			of the device (I/O space)

  			CONFIG_SMC911X_32_BIT

  			Define this if data bus is 32 bits

  			CONFIG_SMC911X_16_BIT

  			Define this if data bus is 16 bits. If your processor
  			automatically converts one 32 bit word to two 16 bit

  			words you may also try CONFIG_SMC911X_32_BIT.

  		CONFIG_SH_ETHER
  		Support for Renesas on-chip Ethernet controller
  
  			CONFIG_SH_ETHER_USE_PORT
  			Define the number of ports to be used
  
  			CONFIG_SH_ETHER_PHY_ADDR
  			Define the ETH PHY's address

  			CONFIG_SH_ETHER_CACHE_WRITEBACK
  			If this option is set, the driver enables cache flush.

  - PWM Support:
  		CONFIG_PWM_IMX
  		Support for PWM modul on the imx6.

  - TPM Support:

  		CONFIG_TPM
  		Support TPM devices.

  		CONFIG_TPM_TIS_I2C
  		Support for i2c bus TPM devices. Only one device
  		per system is supported at this time.
  
  			CONFIG_TPM_TIS_I2C_BUS_NUMBER
  			Define the the i2c bus number for the TPM device
  
  			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
  			Define the TPM's address on the i2c bus
  
  			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
  			Define the burst count bytes upper limit

  		CONFIG_TPM_ATMEL_TWI
  		Support for Atmel TWI TPM device. Requires I2C support.

  		CONFIG_TPM_TIS_LPC

  		Support for generic parallel port TPM devices. Only one device
  		per system is supported at this time.
  
  			CONFIG_TPM_TIS_BASE_ADDRESS
  			Base address where the generic TPM device is mapped
  			to. Contemporary x86 systems usually map it at
  			0xfed40000.

  		CONFIG_CMD_TPM
  		Add tpm monitor functions.
  		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
  		provides monitor access to authorized functions.
  
  		CONFIG_TPM
  		Define this to enable the TPM support library which provides
  		functional interfaces to some TPM commands.
  		Requires support for a TPM device.
  
  		CONFIG_TPM_AUTH_SESSIONS
  		Define this to enable authorized functions in the TPM library.
  		Requires CONFIG_TPM and CONFIG_SHA1.

  - USB Support:
  		At the moment only the UHCI host controller is

  		supported (PIP405, MIP405, MPC5200); define

  		CONFIG_USB_UHCI to enable it.
  		define CONFIG_USB_KEYBOARD to enable the USB Keyboard

  		and define CONFIG_USB_STORAGE to enable the USB

  		storage devices.
  		Note:
  		Supported are USB Keyboards and USB Floppy drives
  		(TEAC FD-05PUB).

  		MPC5200 USB requires additional defines:
  			CONFIG_USB_CLOCK
  				for 528 MHz Clock: 0x0001bbbb

  			CONFIG_PSC3_USB
  				for USB on PSC3

  			CONFIG_USB_CONFIG
  				for differential drivers: 0x00001000
  				for single ended drivers: 0x00005000

  				for differential drivers on PSC3: 0x00000100
  				for single ended drivers on PSC3: 0x00004100

  			CONFIG_SYS_USB_EVENT_POLL

  				May be defined to allow interrupt polling
  				instead of using asynchronous interrupts

  		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
  		txfilltuning field in the EHCI controller on reset.

  		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
  		HW module registers.

  - USB Device:
  		Define the below if you wish to use the USB console.
  		Once firmware is rebuilt from a serial console issue the
  		command "setenv stdin usbtty; setenv stdout usbtty" and

  		attach your USB cable. The Unix command "dmesg" should print

  		it has found a new device. The environment variable usbtty
  		can be set to gserial or cdc_acm to enable your device to

  		appear to a USB host as a Linux gserial device or a

  		Common Device Class Abstract Control Model serial device.
  		If you select usbtty = gserial you should be able to enumerate
  		a Linux host by
  		# modprobe usbserial vendor=0xVendorID product=0xProductID
  		else if using cdc_acm, simply setting the environment
  		variable usbtty to be cdc_acm should suffice. The following
  		might be defined in YourBoardName.h

  			CONFIG_USB_DEVICE
  			Define this to build a UDC device
  
  			CONFIG_USB_TTY
  			Define this to have a tty type of device available to
  			talk to the UDC device

  			CONFIG_USBD_HS
  			Define this to enable the high speed support for usb
  			device and usbtty. If this feature is enabled, a routine
  			int is_usbd_high_speed(void)
  			also needs to be defined by the driver to dynamically poll
  			whether the enumeration has succeded at high speed or full
  			speed.

  			CONFIG_SYS_CONSOLE_IS_IN_ENV

  			Define this if you want stdin, stdout &/or stderr to
  			be set to usbtty.
  
  			mpc8xx:

  				CONFIG_SYS_USB_EXTC_CLK 0xBLAH

  				Derive USB clock from external clock "blah"

  				- CONFIG_SYS_USB_EXTC_CLK 0x02

  				CONFIG_SYS_USB_BRG_CLK 0xBLAH

  				Derive USB clock from brgclk

  				- CONFIG_SYS_USB_BRG_CLK 0x04

  		If you have a USB-IF assigned VendorID then you may wish to

  		define your own vendor specific values either in BoardName.h

  		or directly in usbd_vendor_info.h. If you don't define

  		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
  		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
  		should pretend to be a Linux device to it's target host.
  
  			CONFIG_USBD_MANUFACTURER
  			Define this string as the name of your company for
  			- CONFIG_USBD_MANUFACTURER "my company"

  			CONFIG_USBD_PRODUCT_NAME
  			Define this string as the name of your product
  			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
  
  			CONFIG_USBD_VENDORID
  			Define this as your assigned Vendor ID from the USB
  			Implementors Forum. This *must* be a genuine Vendor ID
  			to avoid polluting the USB namespace.
  			- CONFIG_USBD_VENDORID 0xFFFF

  			CONFIG_USBD_PRODUCTID
  			Define this as the unique Product ID
  			for your device
  			- CONFIG_USBD_PRODUCTID 0xFFFF

  - ULPI Layer Support:
  		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
  		the generic ULPI layer. The generic layer accesses the ULPI PHY
  		via the platform viewport, so you need both the genric layer and
  		the viewport enabled. Currently only Chipidea/ARC based
  		viewport is supported.
  		To enable the ULPI layer support, define CONFIG_USB_ULPI and
  		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.

  		If your ULPI phy needs a different reference clock than the
  		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
  		the appropriate value in Hz.

  - MMC Support:

  		The MMC controller on the Intel PXA is supported. To
  		enable this define CONFIG_MMC. The MMC can be
  		accessed from the boot prompt by mapping the device

  		to physical memory similar to flash. Command line is

  		enabled with CONFIG_CMD_MMC. The MMC driver also works with
  		the FAT fs. This is enabled with CONFIG_CMD_FAT.

  		CONFIG_SH_MMCIF
  		Support for Renesas on-chip MMCIF controller
  
  			CONFIG_SH_MMCIF_ADDR
  			Define the base address of MMCIF registers
  
  			CONFIG_SH_MMCIF_CLK
  			Define the clock frequency for MMCIF

  		CONFIG_GENERIC_MMC
  		Enable the generic MMC driver
  
  		CONFIG_SUPPORT_EMMC_BOOT
  		Enable some additional features of the eMMC boot partitions.
  
  		CONFIG_SUPPORT_EMMC_RPMB
  		Enable the commands for reading, writing and programming the
  		key for the Replay Protection Memory Block partition in eMMC.

  - USB Device Firmware Update (DFU) class support:
  		CONFIG_DFU_FUNCTION
  		This enables the USB portion of the DFU USB class
  
  		CONFIG_CMD_DFU
  		This enables the command "dfu" which is used to have
  		U-Boot create a DFU class device via USB.  This command
  		requires that the "dfu_alt_info" environment variable be
  		set and define the alt settings to expose to the host.
  
  		CONFIG_DFU_MMC
  		This enables support for exposing (e)MMC devices via DFU.

  		CONFIG_DFU_NAND
  		This enables support for exposing NAND devices via DFU.

  		CONFIG_DFU_RAM
  		This enables support for exposing RAM via DFU.
  		Note: DFU spec refer to non-volatile memory usage, but
  		allow usages beyond the scope of spec - here RAM usage,
  		one that would help mostly the developer.

  		CONFIG_SYS_DFU_DATA_BUF_SIZE
  		Dfu transfer uses a buffer before writing data to the
  		raw storage device. Make the size (in bytes) of this buffer
  		configurable. The size of this buffer is also configurable
  		through the "dfu_bufsiz" environment variable.

  		CONFIG_SYS_DFU_MAX_FILE_SIZE
  		When updating files rather than the raw storage device,
  		we use a static buffer to copy the file into and then write
  		the buffer once we've been given the whole file.  Define
  		this to the maximum filesize (in bytes) for the buffer.
  		Default is 4 MiB if undefined.

  		DFU_DEFAULT_POLL_TIMEOUT
  		Poll timeout [ms], is the timeout a device can send to the
  		host. The host must wait for this timeout before sending
  		a subsequent DFU_GET_STATUS request to the device.
  
  		DFU_MANIFEST_POLL_TIMEOUT
  		Poll timeout [ms], which the device sends to the host when
  		entering dfuMANIFEST state. Host waits this timeout, before
  		sending again an USB request to the device.

  - USB Device Android Fastboot support:
  		CONFIG_CMD_FASTBOOT
  		This enables the command "fastboot" which enables the Android
  		fastboot mode for the platform's USB device. Fastboot is a USB
  		protocol for downloading images, flashing and device control
  		used on Android devices.
  		See doc/README.android-fastboot for more information.
  
  		CONFIG_ANDROID_BOOT_IMAGE
  		This enables support for booting images which use the Android
  		image format header.
  
  		CONFIG_USB_FASTBOOT_BUF_ADDR
  		The fastboot protocol requires a large memory buffer for
  		downloads. Define this to the starting RAM address to use for
  		downloaded images.
  
  		CONFIG_USB_FASTBOOT_BUF_SIZE
  		The fastboot protocol requires a large memory buffer for
  		downloads. This buffer should be as large as possible for a
  		platform. Define this to the size available RAM for fastboot.

  
  		CONFIG_FASTBOOT_FLASH
  		The fastboot protocol includes a "flash" command for writing
  		the downloaded image to a non-volatile storage device. Define
  		this to enable the "fastboot flash" command.
  
  		CONFIG_FASTBOOT_FLASH_MMC_DEV
  		The fastboot "flash" command requires additional information
  		regarding the non-volatile storage device. Define this to
  		the eMMC device that fastboot should use to store the image.

  - Journaling Flash filesystem support:
  		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
  		CONFIG_JFFS2_NAND_DEV
  		Define these for a default partition on a NAND device

  		CONFIG_SYS_JFFS2_FIRST_SECTOR,
  		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS

  		Define these for a default partition on a NOR device

  		CONFIG_SYS_JFFS_CUSTOM_PART

  		Define this to create an own partition. You have to provide a
  		function struct part_info* jffs2_part_info(int part_num)
  
  		If you define only one JFFS2 partition you may also want to

  		#define CONFIG_SYS_JFFS_SINGLE_PART	1

  		to disable the command chpart. This is the default when you
  		have not defined a custom partition

  - FAT(File Allocation Table) filesystem write function support:
  		CONFIG_FAT_WRITE

  
  		Define this to enable support for saving memory data as a
  		file in FAT formatted partition.
  
  		This will also enable the command "fatwrite" enabling the
  		user to write files to FAT.

  CBFS (Coreboot Filesystem) support
  		CONFIG_CMD_CBFS
  
  		Define this to enable support for reading from a Coreboot
  		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
  		and cbfsload.

  - FAT(File Allocation Table) filesystem cluster size:
  		CONFIG_FS_FAT_MAX_CLUSTSIZE
  
  		Define the max cluster size for fat operations else
  		a default value of 65536 will be defined.

  - Keyboard Support:
  		CONFIG_ISA_KEYBOARD
  
  		Define this to enable standard (PC-Style) keyboard
  		support
  
  		CONFIG_I8042_KBD
  		Standard PC keyboard driver with US (is default) and
  		GERMAN key layout (switch via environment 'keymap=de') support.
  		Export function i8042_kbd_init, i8042_tstc and i8042_getc
  		for cfb_console. Supports cursor blinking.

  		CONFIG_CROS_EC_KEYB
  		Enables a Chrome OS keyboard using the CROS_EC interface.
  		This uses CROS_EC to communicate with a second microcontroller
  		which provides key scans on request.

  - Video support:
  		CONFIG_VIDEO
  
  		Define this to enable video support (for output to
  		video).
  
  		CONFIG_VIDEO_CT69000
  
  		Enable Chips & Technologies 69000 Video chip
  
  		CONFIG_VIDEO_SMI_LYNXEM

  		Enable Silicon Motion SMI 712/710/810 Video chip. The

  		video output is selected via environment 'videoout'
  		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
  		assumed.

  		For the CT69000 and SMI_LYNXEM drivers, videomode is

  		selected via environment 'videomode'. Two different ways

  		are possible:
  		- "videomode=num"   'num' is a standard LiLo mode numbers.

  		Following standard modes are supported	(* is default):

  
  		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
  		-------------+---------------------------------------------
  		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
  		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
  		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
  		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
  		-------------+---------------------------------------------

  		(i.e. setenv videomode 317; saveenv; reset;)

  		- "videomode=bootargs" all the video parameters are parsed

  		from the bootargs. (See drivers/video/videomodes.c)

  		CONFIG_VIDEO_SED13806

  		Enable Epson SED13806 driver. This driver supports 8bpp

  		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
  		or CONFIG_VIDEO_SED13806_16BPP

  		CONFIG_FSL_DIU_FB

  		Enable the Freescale DIU video driver.	Reference boards for

  		SOCs that have a DIU should define this macro to enable DIU
  		support, and should also define these other macros:
  
  			CONFIG_SYS_DIU_ADDR
  			CONFIG_VIDEO
  			CONFIG_CMD_BMP
  			CONFIG_CFB_CONSOLE
  			CONFIG_VIDEO_SW_CURSOR
  			CONFIG_VGA_AS_SINGLE_DEVICE
  			CONFIG_VIDEO_LOGO
  			CONFIG_VIDEO_BMP_LOGO

  		The DIU driver will look for the 'video-mode' environment
  		variable, and if defined, enable the DIU as a console during
  		boot.  See the documentation file README.video for a
  		description of this variable.

  		CONFIG_VIDEO_VGA
  
  		Enable the VGA video / BIOS for x86. The alternative if you
  		are using coreboot is to use the coreboot frame buffer
  		driver.

  - Keyboard Support:

  		CONFIG_KEYBOARD

  		Define this to enable a custom keyboard support.
  		This simply calls drv_keyboard_init() which must be
  		defined in your board-specific files.
  		The only board using this so far is RBC823.

  - LCD Support:	CONFIG_LCD
  
  		Define this to enable LCD support (for output to LCD
  		display); also select one of the supported displays
  		by defining one of these:

  		CONFIG_ATMEL_LCD:
  
  			HITACHI TX09D70VM1CCA, 3.5", 240x320.

  		CONFIG_NEC_NL6448AC33:

  			NEC NL6448AC33-18. Active, color, single scan.

  		CONFIG_NEC_NL6448BC20

  			NEC NL6448BC20-08. 6.5", 640x480.
  			Active, color, single scan.
  
  		CONFIG_NEC_NL6448BC33_54
  
  			NEC NL6448BC33-54. 10.4", 640x480.

  			Active, color, single scan.
  
  		CONFIG_SHARP_16x9
  
  			Sharp 320x240. Active, color, single scan.
  			It isn't 16x9, and I am not sure what it is.
  
  		CONFIG_SHARP_LQ64D341
  
  			Sharp LQ64D341 display, 640x480.
  			Active, color, single scan.
  
  		CONFIG_HLD1045
  
  			HLD1045 display, 640x480.
  			Active, color, single scan.
  
  		CONFIG_OPTREX_BW
  
  			Optrex	 CBL50840-2 NF-FW 99 22 M5
  			or
  			Hitachi	 LMG6912RPFC-00T
  			or
  			Hitachi	 SP14Q002
  
  			320x240. Black & white.
  
  		Normally display is black on white background; define

  		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.

  		CONFIG_LCD_ALIGNMENT
  
  		Normally the LCD is page-aligned (tyically 4KB). If this is
  		defined then the LCD will be aligned to this value instead.
  		For ARM it is sometimes useful to use MMU_SECTION_SIZE
  		here, since it is cheaper to change data cache settings on
  		a per-section basis.

  		CONFIG_CONSOLE_SCROLL_LINES
  
  		When the console need to be scrolled, this is the number of
  		lines to scroll by. It defaults to 1. Increasing this makes
  		the console jump but can help speed up operation when scrolling
  		is slow.

  		CONFIG_LCD_BMP_RLE8
  
  		Support drawing of RLE8-compressed bitmaps on the LCD.

  		CONFIG_I2C_EDID
  
  		Enables an 'i2c edid' command which can read EDID
  		information over I2C from an attached LCD display.

  - Splash Screen Support: CONFIG_SPLASH_SCREEN

  		If this option is set, the environment is checked for
  		a variable "splashimage". If found, the usual display
  		of logo, copyright and system information on the LCD

  		is suppressed and the BMP image at the address

  		specified in "splashimage" is loaded instead. The
  		console is redirected to the "nulldev", too. This
  		allows for a "silent" boot where a splash screen is
  		loaded very quickly after power-on.

  		CONFIG_SPLASHIMAGE_GUARD
  
  		If this option is set, then U-Boot will prevent the environment
  		variable "splashimage" from being set to a problematic address

  		(see README.displaying-bmps).

  		This option is useful for targets where, due to alignment
  		restrictions, an improperly aligned BMP image will cause a data
  		abort. If you think you will not have problems with unaligned
  		accesses (for example because your toolchain prevents them)
  		there is no need to set this option.

  		CONFIG_SPLASH_SCREEN_ALIGN
  
  		If this option is set the splash image can be freely positioned
  		on the screen. Environment variable "splashpos" specifies the
  		position as "x,y". If a positive number is given it is used as
  		number of pixel from left/top. If a negative number is given it
  		is used as number of pixel from right/bottom. You can also
  		specify 'm' for centering the image.
  
  		Example:
  		setenv splashpos m,m
  			=> image at center of screen
  
  		setenv splashpos 30,20
  			=> image at x = 30 and y = 20
  
  		setenv splashpos -10,m
  			=> vertically centered image
  			   at x = dspWidth - bmpWidth - 9

  - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
  
  		If this option is set, additionally to standard BMP
  		images, gzipped BMP images can be displayed via the
  		splashscreen support or the bmp command.

  - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
  
  		If this option is set, 8-bit RLE compressed BMP images
  		can be displayed via the splashscreen support or the
  		bmp command.

  - Do compresssing for memory range:
  		CONFIG_CMD_ZIP
  
  		If this option is set, it would use zlib deflate method
  		to compress the specified memory at its best effort.

  - Compression support:

  		CONFIG_GZIP
  
  		Enabled by default to support gzip compressed images.

  		CONFIG_BZIP2
  
  		If this option is set, support for bzip2 compressed
  		images is included. If not, only uncompressed and gzip
  		compressed images are supported.

  		NOTE: the bzip2 algorithm requires a lot of RAM, so

  		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should

  		be at least 4MB.

  		CONFIG_LZMA
  
  		If this option is set, support for lzma compressed
  		images is included.
  
  		Note: The LZMA algorithm adds between 2 and 4KB of code and it
  		requires an amount of dynamic memory that is given by the
  		formula:
  
  			(1846 + 768 << (lc + lp)) * sizeof(uint16)
  
  		Where lc and lp stand for, respectively, Literal context bits
  		and Literal pos bits.
  
  		This value is upper-bounded by 14MB in the worst case. Anyway,
  		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
  		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
  		a very small buffer.
  
  		Use the lzmainfo tool to determinate the lc and lp values and
  		then calculate the amount of needed dynamic memory (ensuring

  		the appropriate CONFIG_SYS_MALLOC_LEN value).

  		CONFIG_LZO
  
  		If this option is set, support for LZO compressed images
  		is included.

  - MII/PHY support:
  		CONFIG_PHY_ADDR
  
  		The address of PHY on MII bus.
  
  		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
  
  		The clock frequency of the MII bus
  
  		CONFIG_PHY_GIGE
  
  		If this option is set, support for speed/duplex

  		detection of gigabit PHY is included.

  
  		CONFIG_PHY_RESET_DELAY
  
  		Some PHY like Intel LXT971A need extra delay after
  		reset before any MII register access is possible.
  		For such PHY, set this option to the usec delay
  		required. (minimum 300usec for LXT971A)
  
  		CONFIG_PHY_CMD_DELAY (ppc4xx)
  
  		Some PHY like Intel LXT971A need extra delay after
  		command issued before MII status register can be read

  - Ethernet address:
  		CONFIG_ETHADDR

  		CONFIG_ETH1ADDR

  		CONFIG_ETH2ADDR
  		CONFIG_ETH3ADDR

  		CONFIG_ETH4ADDR
  		CONFIG_ETH5ADDR

  		Define a default value for Ethernet address to use
  		for the respective Ethernet interface, in case this

  		is not determined automatically.
  
  - IP address:
  		CONFIG_IPADDR
  
  		Define a default value for the IP address to use for

  		the default Ethernet interface, in case this is not

  		determined through e.g. bootp.

  		(Environment variable "ipaddr")

  
  - Server IP address:
  		CONFIG_SERVERIP

  		Defines a default value for the IP address of a TFTP

  		server to contact when using the "tftboot" command.

  		(Environment variable "serverip")

  		CONFIG_KEEP_SERVERADDR
  
  		Keeps the server's MAC address, in the env 'serveraddr'
  		for passing to bootargs (like Linux's netconsole option)

  - Gateway IP address:
  		CONFIG_GATEWAYIP
  
  		Defines a default value for the IP address of the
  		default router where packets to other networks are
  		sent to.
  		(Environment variable "gatewayip")
  
  - Subnet mask:
  		CONFIG_NETMASK
  
  		Defines a default value for the subnet mask (or
  		routing prefix) which is used to determine if an IP
  		address belongs to the local subnet or needs to be
  		forwarded through a router.
  		(Environment variable "netmask")

  - Multicast TFTP Mode:
  		CONFIG_MCAST_TFTP
  
  		Defines whether you want to support multicast TFTP as per
  		rfc-2090; for example to work with atftp.  Lets lots of targets

  		tftp down the same boot image concurrently.  Note: the Ethernet

  		driver in use must provide a function: mcast() to join/leave a
  		multicast group.

  - BOOTP Recovery Mode:
  		CONFIG_BOOTP_RANDOM_DELAY
  
  		If you have many targets in a network that try to
  		boot using BOOTP, you may want to avoid that all
  		systems send out BOOTP requests at precisely the same
  		moment (which would happen for instance at recovery
  		from a power failure, when all systems will try to
  		boot, thus flooding the BOOTP server. Defining
  		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
  		inserted before sending out BOOTP requests. The

  		following delays are inserted then:

  
  		1st BOOTP request:	delay 0 ... 1 sec
  		2nd BOOTP request:	delay 0 ... 2 sec
  		3rd BOOTP request:	delay 0 ... 4 sec
  		4th and following
  		BOOTP requests:		delay 0 ... 8 sec

  		CONFIG_BOOTP_ID_CACHE_SIZE
  
  		BOOTP packets are uniquely identified using a 32-bit ID. The
  		server will copy the ID from client requests to responses and
  		U-Boot will use this to determine if it is the destination of
  		an incoming response. Some servers will check that addresses
  		aren't in use before handing them out (usually using an ARP
  		ping) and therefore take up to a few hundred milliseconds to
  		respond. Network congestion may also influence the time it
  		takes for a response to make it back to the client. If that
  		time is too long, U-Boot will retransmit requests. In order
  		to allow earlier responses to still be accepted after these
  		retransmissions, U-Boot's BOOTP client keeps a small cache of
  		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
  		cache. The default is to keep IDs for up to four outstanding
  		requests. Increasing this will allow U-Boot to accept offers
  		from a BOOTP client in networks with unusually high latency.

  - DHCP Advanced Options:

  		You can fine tune the DHCP functionality by defining
  		CONFIG_BOOTP_* symbols:
  
  		CONFIG_BOOTP_SUBNETMASK
  		CONFIG_BOOTP_GATEWAY
  		CONFIG_BOOTP_HOSTNAME
  		CONFIG_BOOTP_NISDOMAIN
  		CONFIG_BOOTP_BOOTPATH
  		CONFIG_BOOTP_BOOTFILESIZE
  		CONFIG_BOOTP_DNS
  		CONFIG_BOOTP_DNS2
  		CONFIG_BOOTP_SEND_HOSTNAME
  		CONFIG_BOOTP_NTPSERVER
  		CONFIG_BOOTP_TIMEOFFSET
  		CONFIG_BOOTP_VENDOREX

  		CONFIG_BOOTP_MAY_FAIL

  		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
  		environment variable, not the BOOTP server.

  		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
  		after the configured retry count, the call will fail
  		instead of starting over.  This can be used to fail over
  		to Link-local IP address configuration if the DHCP server
  		is not available.

  		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
  		serverip from a DHCP server, it is possible that more
  		than one DNS serverip is offered to the client.
  		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
  		serverip will be stored in the additional environment
  		variable "dnsip2". The first DNS serverip is always
  		stored in the variable "dnsip", when CONFIG_BOOTP_DNS

  		is defined.

  
  		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
  		to do a dynamic update of a DNS server. To do this, they
  		need the hostname of the DHCP requester.

  		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content

  		of the "hostname" environment variable is passed as
  		option 12 to the DHCP server.

  		CONFIG_BOOTP_DHCP_REQUEST_DELAY
  
  		A 32bit value in microseconds for a delay between
  		receiving a "DHCP Offer" and sending the "DHCP Request".
  		This fixes a problem with certain DHCP servers that don't
  		respond 100% of the time to a "DHCP request". E.g. On an
  		AT91RM9200 processor running at 180MHz, this delay needed
  		to be *at least* 15,000 usec before a Windows Server 2003
  		DHCP server would reply 100% of the time. I recommend at
  		least 50,000 usec to be safe. The alternative is to hope
  		that one of the retries will be successful but note that
  		the DHCP timeout and retry process takes a longer than
  		this delay.

   - Link-local IP address negotiation:
  		Negotiate with other link-local clients on the local network
  		for an address that doesn't require explicit configuration.
  		This is especially useful if a DHCP server cannot be guaranteed
  		to exist in all environments that the device must operate.
  
  		See doc/README.link-local for more information.

   - CDP Options:

  		CONFIG_CDP_DEVICE_ID

  
  		The device id used in CDP trigger frames.
  
  		CONFIG_CDP_DEVICE_ID_PREFIX
  
  		A two character string which is prefixed to the MAC address
  		of the device.
  
  		CONFIG_CDP_PORT_ID
  
  		A printf format string which contains the ascii name of
  		the port. Normally is set to "eth%d" which sets

  		eth0 for the first Ethernet, eth1 for the second etc.

  
  		CONFIG_CDP_CAPABILITIES
  
  		A 32bit integer which indicates the device capabilities;
  		0x00000010 for a normal host which does not forwards.
  
  		CONFIG_CDP_VERSION
  
  		An ascii string containing the version of the software.
  
  		CONFIG_CDP_PLATFORM
  
  		An ascii string containing the name of the platform.
  
  		CONFIG_CDP_TRIGGER
  
  		A 32bit integer sent on the trigger.
  
  		CONFIG_CDP_POWER_CONSUMPTION
  
  		A 16bit integer containing the power consumption of the
  		device in .1 of milliwatts.
  
  		CONFIG_CDP_APPLIANCE_VLAN_TYPE
  
  		A byte containing the id of the VLAN.

  - Status LED:	CONFIG_STATUS_LED
  
  		Several configurations allow to display the current
  		status using a LED. For instance, the LED will blink
  		fast while running U-Boot code, stop blinking as
  		soon as a reply to a BOOTP request was received, and
  		start blinking slow once the Linux kernel is running
  		(supported by a status LED driver in the Linux
  		kernel). Defining CONFIG_STATUS_LED enables this
  		feature in U-Boot.

  		Additional options:
  
  		CONFIG_GPIO_LED
  		The status LED can be connected to a GPIO pin.
  		In such cases, the gpio_led driver can be used as a
  		status LED backend implementation. Define CONFIG_GPIO_LED
  		to include the gpio_led driver in the U-Boot binary.

  		CONFIG_GPIO_LED_INVERTED_TABLE
  		Some GPIO connected LEDs may have inverted polarity in which
  		case the GPIO high value corresponds to LED off state and
  		GPIO low value corresponds to LED on state.
  		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
  		with a list of GPIO LEDs that have inverted polarity.

  - CAN Support:	CONFIG_CAN_DRIVER
  
  		Defining CONFIG_CAN_DRIVER enables CAN driver support
  		on those systems that support this (optional)
  		feature, like the TQM8xxL modules.

  - I2C Support:	CONFIG_SYS_I2C
  
  		This enable the NEW i2c subsystem, and will allow you to use
  		i2c commands at the u-boot command line (as long as you set
  		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
  		based realtime clock chips or other i2c devices. See
  		common/cmd_i2c.c for a description of the command line
  		interface.
  
  		ported i2c driver to the new framework:

  		- drivers/i2c/soft_i2c.c:
  		  - activate first bus with CONFIG_SYS_I2C_SOFT define
  		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
  		    for defining speed and slave address
  		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
  		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
  		    for defining speed and slave address
  		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
  		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
  		    for defining speed and slave address
  		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
  		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
  		    for defining speed and slave address

  		- drivers/i2c/fsl_i2c.c:
  		  - activate i2c driver with CONFIG_SYS_I2C_FSL
  		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
  		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
  		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
  		    bus.

  		  - If your board supports a second fsl i2c bus, define

  		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
  		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
  		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
  		    second bus.

  		- drivers/i2c/tegra_i2c.c:

  		  - activate this driver with CONFIG_SYS_I2C_TEGRA
  		  - This driver adds 4 i2c buses with a fix speed from
  		    100000 and the slave addr 0!

  		- drivers/i2c/ppc4xx_i2c.c
  		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
  		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
  		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1

  		- drivers/i2c/i2c_mxc.c
  		  - activate this driver with CONFIG_SYS_I2C_MXC
  		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
  		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
  		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
  		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
  		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
  		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
  		If thoses defines are not set, default value is 100000
  		for speed, and 0 for slave.

  		- drivers/i2c/rcar_i2c.c:
  		  - activate this driver with CONFIG_SYS_I2C_RCAR
  		  - This driver adds 4 i2c buses
  
  		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
  		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
  		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
  		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
  		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
  		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
  		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
  		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
  		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses

  		- drivers/i2c/sh_i2c.c:
  		  - activate this driver with CONFIG_SYS_I2C_SH
  		  - This driver adds from 2 to 5 i2c buses
  
  		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
  		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
  		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
  		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
  		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
  		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
  		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
  		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
  		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
  		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
  		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
  		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
  		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses

  		- drivers/i2c/omap24xx_i2c.c
  		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
  		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
  		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
  		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
  		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
  		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
  		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
  		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
  		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
  		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
  		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4

  		- drivers/i2c/zynq_i2c.c
  		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
  		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
  		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr

  		- drivers/i2c/s3c24x0_i2c.c:
  		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
  		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
  		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
  		    with a fix speed from 100000 and the slave addr 0!

  		- drivers/i2c/ihs_i2c.c
  		  - activate this driver with CONFIG_SYS_I2C_IHS
  		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
  		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
  		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
  		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
  		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
  		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
  		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
  		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
  		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
  		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
  		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
  		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3

  		additional defines:
  
  		CONFIG_SYS_NUM_I2C_BUSES
  		Hold the number of i2c busses you want to use. If you
  		don't use/have i2c muxes on your i2c bus, this
  		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
  		omit this define.
  
  		CONFIG_SYS_I2C_DIRECT_BUS
  		define this, if you don't use i2c muxes on your hardware.
  		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
  		omit this define.
  
  		CONFIG_SYS_I2C_MAX_HOPS
  		define how many muxes are maximal consecutively connected
  		on one i2c bus. If you not use i2c muxes, omit this
  		define.
  
  		CONFIG_SYS_I2C_BUSES
  		hold a list of busses you want to use, only used if
  		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
  		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
  		CONFIG_SYS_NUM_I2C_BUSES = 9:
  
  		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
  					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
  					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
  					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
  					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
  					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
  					{1, {I2C_NULL_HOP}}, \
  					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
  					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
  					}
  
  		which defines
  			bus 0 on adapter 0 without a mux

  			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
  			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
  			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
  			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
  			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5

  			bus 6 on adapter 1 without a mux

  			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
  			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2

  
  		If you do not have i2c muxes on your board, omit this define.

  - Legacy I2C Support:	CONFIG_HARD_I2C

  
  		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
  		provides the following compelling advantages:
  
  		- more than one i2c adapter is usable
  		- approved multibus support
  		- better i2c mux support
  
  		** Please consider updating your I2C driver now. **

  		These enable legacy I2C serial bus commands. Defining
  		CONFIG_HARD_I2C will include the appropriate I2C driver
  		for the selected CPU.

  		This will allow you to use i2c commands at the u-boot

  		command line (as long as you set CONFIG_CMD_I2C in

  		CONFIG_COMMANDS) and communicate with i2c based realtime
  		clock chips. See common/cmd_i2c.c for a description of the

  		command line interface.

  		CONFIG_HARD_I2C selects a hardware I2C controller.

  		There are several other quantities that must also be

  		defined when you define CONFIG_HARD_I2C.

  		In both cases you will need to define CONFIG_SYS_I2C_SPEED

  		to be the frequency (in Hz) at which you wish your i2c bus

  		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie

  		the CPU's i2c node address).

  		Now, the u-boot i2c code for the mpc8xx

  		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node

  		and so its address should therefore be cleared to 0 (See,
  		eg, MPC823e User's Manual p.16-473). So, set
  		CONFIG_SYS_I2C_SLAVE to 0.