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  • 			Define this to hold the physical address
    			of the device (I/O space)
    
    
    			Define this if data bus is 32 bits
    
    
    			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.
    
    
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    - USB Support:
    		At the moment only the UHCI host controller is
    
    		supported (PIP405, MIP405, MPC5200); define
    
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    		CONFIG_USB_UHCI to enable it.
    		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
    
    		and define CONFIG_USB_STORAGE to enable the USB
    
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    		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
    
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    				May be defined to allow interrupt polling
    				instead of using asynchronous interrupts
    
    - 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
    
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    		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
    
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    			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
    
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    			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
    
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    				CONFIG_SYS_USB_BRG_CLK 0xBLAH
    
    				Derive USB clock from brgclk
    
    				- CONFIG_SYS_USB_BRG_CLK 0x04
    
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    		If you have a USB-IF assigned VendorID then you may wish to
    
    		define your own vendor specific values either in BoardName.h
    
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    		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"
    
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    			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
    
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    			CONFIG_USBD_PRODUCTID
    			Define this as the unique Product ID
    			for your device
    			- CONFIG_USBD_PRODUCTID 0xFFFF
    
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    		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
    
    
    - 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
    
    
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    - 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.
    
    - 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
    
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    		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.
    
    
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    		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.
    
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    		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
    		-------------+---------------------------------------------
    
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    		(i.e. setenv videomode 317; saveenv; reset;)
    
    
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    		- "videomode=bootargs" all the video parameters are parsed
    
    		from the bootargs. (See drivers/video/videomodes.c)
    
    		Enable Epson SED13806 driver. This driver supports 8bpp
    
    		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
    		or CONFIG_VIDEO_SED13806_16BPP
    
    
    		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.
    
    - Keyboard Support:
    
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    		CONFIG_KEYBOARD
    
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    		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.
    
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    - 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:
    
    
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    		CONFIG_ATMEL_LCD:
    
    			HITACHI TX09D70VM1CCA, 3.5", 240x320.
    
    
    		CONFIG_NEC_NL6448AC33:
    
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    			NEC NL6448AC33-18. Active, color, single scan.
    
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    		CONFIG_NEC_NL6448BC20
    
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    			NEC NL6448BC20-08. 6.5", 640x480.
    			Active, color, single scan.
    
    		CONFIG_NEC_NL6448BC33_54
    
    			NEC NL6448BC33-54. 10.4", 640x480.
    
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    			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.
    
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    - Splash Screen Support: CONFIG_SPLASH_SCREEN
    
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    		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
    
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    		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_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.
    
    
    - Compression support:
    		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).
    
    - 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
    
    
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    - Ethernet address:
    		CONFIG_ETHADDR
    
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    		CONFIG_ETH2ADDR
    		CONFIG_ETH3ADDR
    
    		CONFIG_ETH4ADDR
    		CONFIG_ETH5ADDR
    
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    		Define a default value for Ethernet address to use
    		for the respective Ethernet interface, in case this
    
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    		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
    
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    		determined through e.g. bootp.
    
    - Server IP address:
    		CONFIG_SERVERIP
    
    
    		Defines a default value for the IP address of a TFTP
    
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    		server to contact when using the "tftboot" command.
    
    
    		CONFIG_KEEP_SERVERADDR
    
    		Keeps the server's MAC address, in the env 'serveraddr'
    		for passing to bootargs (like Linux's netconsole option)
    
    
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    - 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
    
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    		driver in use must provide a function: mcast() to join/leave a
    		multicast group.
    
    
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    - 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:
    
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    		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
    
    
    		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_SERVERIP - TFTP server will be the serverip
    		environment variable, not the BOOTP server.
    
    
    		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
    
    
    		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.
    
    
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    		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.
    
    
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    - 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.
    
    - 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_HARD_I2C | CONFIG_SOFT_I2C
    
    
    		These enable I2C serial bus commands. Defining either of
    
    		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
    
    		include the appropriate I2C driver for the selected CPU.
    
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    		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.
    
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    		CONFIG_HARD_I2C selects a hardware I2C controller.
    
    		CONFIG_SOFT_I2C configures u-boot to use a software (aka
    
    		bit-banging) driver instead of CPM or similar hardware
    		support for I2C.
    
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    		There are several other quantities that must also be
    
    		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
    
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    		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.
    
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    		CONFIG_SYS_I2C_INIT_MPC5XXX
    
    		When a board is reset during an i2c bus transfer
    		chips might think that the current transfer is still
    		in progress.  Reset the slave devices by sending start
    		commands until the slave device responds.
    
    
    		That's all that's required for CONFIG_HARD_I2C.
    
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    		If you use the software i2c interface (CONFIG_SOFT_I2C)
    		then the following macros need to be defined (examples are
    		from include/configs/lwmon.h):
    
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    		I2C_INIT
    
    
    		(Optional). Any commands necessary to enable the I2C
    
    		controller or configure ports.
    
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    		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
    
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    		I2C_PORT
    
    
    		(Only for MPC8260 CPU). The I/O port to use (the code
    		assumes both bits are on the same port). Valid values
    		are 0..3 for ports A..D.
    
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    		I2C_ACTIVE
    
    		The code necessary to make the I2C data line active
    		(driven).  If the data line is open collector, this
    		define can be null.
    
    
    		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
    
    
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    		I2C_TRISTATE
    
    		The code necessary to make the I2C data line tri-stated
    		(inactive).  If the data line is open collector, this
    		define can be null.
    
    
    		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
    
    
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    		I2C_READ
    
    		Code that returns TRUE if the I2C data line is high,
    		FALSE if it is low.
    
    
    		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
    
    
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    		I2C_SDA(bit)
    
    		If <bit> is TRUE, sets the I2C data line high. If it
    		is FALSE, it clears it (low).
    
    
    		eg: #define I2C_SDA(bit) \
    
    			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
    
    			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
    
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    		I2C_SCL(bit)
    
    		If <bit> is TRUE, sets the I2C clock line high. If it
    		is FALSE, it clears it (low).
    
    
    		eg: #define I2C_SCL(bit) \
    
    			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
    
    			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
    
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    		I2C_DELAY
    
    		This delay is invoked four times per clock cycle so this
    		controls the rate of data transfer.  The data rate thus
    
    		is 1 / (I2C_DELAY * 4). Often defined to be something
    
    		#define I2C_DELAY  udelay(2)
    
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    		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
    
    		If your arch supports the generic GPIO framework (asm/gpio.h),
    		then you may alternatively define the two GPIOs that are to be
    		used as SCL / SDA.  Any of the previous I2C_xxx macros will
    		have GPIO-based defaults assigned to them as appropriate.
    
    		You should define these to the GPIO value as given directly to
    		the generic GPIO functions.
    
    
    		CONFIG_SYS_I2C_INIT_BOARD
    
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    		When a board is reset during an i2c bus transfer
    		chips might think that the current transfer is still
    		in progress. On some boards it is possible to access
    		the i2c SCLK line directly, either by using the
    		processor pin as a GPIO or by having a second pin
    		connected to the bus. If this option is defined a
    		custom i2c_init_board() routine in boards/xxx/board.c
    		is run early in the boot sequence.
    
    		CONFIG_SYS_I2C_BOARD_LATE_INIT
    
    		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
    		defined a custom i2c_board_late_init() routine in
    		boards/xxx/board.c is run AFTER the operations in i2c_init()
    		is completed. This callpoint can be used to unreset i2c bus
    		using CPU i2c controller register accesses for CPUs whose i2c
    		controller provide such a method. It is called at the end of
    		i2c_init() to allow i2c_init operations to setup the i2c bus
    		controller on the CPU (e.g. setting bus speed & slave address).
    
    
    		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
    
    		This option enables configuration of bi_iic_fast[] flags
    		in u-boot bd_info structure based on u-boot environment
    		variable "i2cfast". (see also i2cfast)
    
    
    		CONFIG_I2C_MULTI_BUS
    
    		This option allows the use of multiple I2C buses, each of which
    		must have a controller.  At any point in time, only one bus is
    		active.  To switch to a different bus, use the 'i2c dev' command.
    		Note that bus numbering is zero-based.
    
    
    		CONFIG_SYS_I2C_NOPROBES
    
    
    		This option specifies a list of I2C devices that will be skipped
    
    		when the 'i2c probe' command is issued.  If CONFIG_I2C_MULTI_BUS
    		is set, specify a list of bus-device pairs.  Otherwise, specify
    		a 1D array of device addresses
    
    
    		e.g.
    			#undef	CONFIG_I2C_MULTI_BUS
    
    			#define CONFIG_SYS_I2C_NOPROBES	{0x50,0x68}
    
    
    		will skip addresses 0x50 and 0x68 on a board with one I2C bus
    
    			#define	CONFIG_I2C_MULTI_BUS
    
    			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
    
    
    		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
    
    
    		CONFIG_SYS_SPD_BUS_NUM
    
    
    		If defined, then this indicates the I2C bus number for DDR SPD.
    		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
    
    
    		CONFIG_SYS_RTC_BUS_NUM
    
    
    		If defined, then this indicates the I2C bus number for the RTC.
    		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
    
    
    		CONFIG_SYS_DTT_BUS_NUM
    
    
    		If defined, then this indicates the I2C bus number for the DTT.
    		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
    
    
    		CONFIG_SYS_I2C_DTT_ADDR:
    
    
    		If defined, specifies the I2C address of the DTT device.
    		If not defined, then U-Boot uses predefined value for
    		specified DTT device.
    
    
    		CONFIG_FSL_I2C
    
    		Define this option if you want to use Freescale's I2C driver in
    
    		drivers/i2c/fsl_i2c.c.
    
    		CONFIG_I2C_MUX
    
    		Define this option if you have I2C devices reached over 1 .. n
    		I2C Muxes like the pca9544a. This option addes a new I2C
    		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
    		new I2C Bus to the existing I2C Busses. If you select the
    		new Bus with "i2c dev", u-bbot sends first the commandos for
    		the muxes to activate this new "bus".
    
    		CONFIG_I2C_MULTI_BUS must be also defined, to use this
    		feature!
    
    		Example:
    		Adding a new I2C Bus reached over 2 pca9544a muxes
    			The First mux with address 70 and channel 6
    			The Second mux with address 71 and channel 4
    
    		=> i2c bus pca9544a:70:6:pca9544a:71:4
    
    		Use the "i2c bus" command without parameter, to get a list
    		of I2C Busses with muxes:
    
    		=> i2c bus
    		Busses reached over muxes:
    		Bus ID: 2
    		  reached over Mux(es):
    		    pca9544a@70 ch: 4
    		Bus ID: 3
    		  reached over Mux(es):
    		    pca9544a@70 ch: 6
    		    pca9544a@71 ch: 4
    		=>
    
    		If you now switch to the new I2C Bus 3 with "i2c dev 3"
    
    		u-boot first sends the command to the mux@70 to enable
    		channel 6, and then the command to the mux@71 to enable
    
    		the channel 4.
    
    		After that, you can use the "normal" i2c commands as
    
    		usual to communicate with your I2C devices behind
    
    		the 2 muxes.
    
    		This option is actually implemented for the bitbanging
    		algorithm in common/soft_i2c.c and for the Hardware I2C
    		Bus on the MPC8260. But it should be not so difficult
    		to add this option to other architectures.
    
    
    		CONFIG_SOFT_I2C_READ_REPEATED_START
    
    		defining this will force the i2c_read() function in
    		the soft_i2c driver to perform an I2C repeated start
    		between writing the address pointer and reading the
    		data.  If this define is omitted the default behaviour
    		of doing a stop-start sequence will be used.  Most I2C
    		devices can use either method, but some require one or
    		the other.
    
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    - SPI Support:	CONFIG_SPI
    
    		Enables SPI driver (so far only tested with
    		SPI EEPROM, also an instance works with Crystal A/D and
    		D/As on the SACSng board)
    
    
    		CONFIG_SH_SPI
    
    		Enables the driver for SPI controller on SuperH. Currently
    		only SH7757 is supported.
    
    
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    		CONFIG_SPI_X
    
    		Enables extended (16-bit) SPI EEPROM addressing.
    		(symmetrical to CONFIG_I2C_X)
    
    		CONFIG_SOFT_SPI
    
    
    		Enables a software (bit-bang) SPI driver rather than
    		using hardware support. This is a general purpose
    		driver that only requires three general I/O port pins
    		(two outputs, one input) to function. If this is
    		defined, the board configuration must define several
    		SPI configuration items (port pins to use, etc). For
    		an example, see include/configs/sacsng.h.
    
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    		CONFIG_HARD_SPI
    
    		Enables a hardware SPI driver for general-purpose reads
    		and writes.  As with CONFIG_SOFT_SPI, the board configuration
    		must define a list of chip-select function pointers.
    		Currently supported on some MPC8xxx processors.  For an
    		example, see include/configs/mpc8349emds.h.
    
    
    		CONFIG_MXC_SPI
    
    		Enables the driver for the SPI controllers on i.MX and MXC
    		SoCs. Currently only i.MX31 is supported.
    
    
    - FPGA Support: CONFIG_FPGA
    
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    		Enables FPGA subsystem.
    
    		CONFIG_FPGA_<vendor>
    
    		Enables support for specific chip vendors.
    		(ALTERA, XILINX)
    
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    		CONFIG_FPGA_<family>
    
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    		Enables support for FPGA family.
    		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
    
    		CONFIG_FPGA_COUNT
    
    		Specify the number of FPGA devices to support.
    
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    		CONFIG_SYS_FPGA_PROG_FEEDBACK
    
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    		Enable printing of hash marks during FPGA configuration.
    
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    		CONFIG_SYS_FPGA_CHECK_BUSY
    
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    		Enable checks on FPGA configuration interface busy
    		status by the configuration function. This option
    		will require a board or device specific function to
    		be written.
    
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    		CONFIG_FPGA_DELAY
    
    		If defined, a function that provides delays in the FPGA
    		configuration driver.
    
    
    		CONFIG_SYS_FPGA_CHECK_CTRLC
    
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    		Allow Control-C to interrupt FPGA configuration
    
    
    		CONFIG_SYS_FPGA_CHECK_ERROR
    
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    		Check for configuration errors during FPGA bitfile
    		loading. For example, abort during Virtex II
    		configuration if the INIT_B line goes low (which
    		indicated a CRC error).
    
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    		CONFIG_SYS_FPGA_WAIT_INIT
    
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    		Maximum time to wait for the INIT_B line to deassert
    		after PROB_B has been deasserted during a Virtex II
    		FPGA configuration sequence. The default time is 500
    
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    		CONFIG_SYS_FPGA_WAIT_BUSY
    
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    		Maximum time to wait for BUSY to deassert during
    
    		Virtex II FPGA configuration. The default is 5 ms.
    
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    		CONFIG_SYS_FPGA_WAIT_CONFIG
    
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    		Time to wait after FPGA configuration. The default is
    
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    - Configuration Management:
    		CONFIG_IDENT_STRING
    
    
    		If defined, this string will be added to the U-Boot
    		version information (U_BOOT_VERSION)
    
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    - Vendor Parameter Protection:
    
    
    		U-Boot considers the values of the environment
    		variables "serial#" (Board Serial Number) and
    
    		"ethaddr" (Ethernet Address) to be parameters that
    
    		are set once by the board vendor / manufacturer, and
    		protects these variables from casual modification by
    		the user. Once set, these variables are read-only,
    		and write or delete attempts are rejected. You can
    
    		change this behaviour:
    
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    		If CONFIG_ENV_OVERWRITE is #defined in your config
    		file, the write protection for vendor parameters is
    
    		completely disabled. Anybody can change or delete
    
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    		these parameters.
    
    		Alternatively, if you #define _both_ CONFIG_ETHADDR
    		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
    
    		Ethernet address is installed in the environment,
    
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    		which can be changed exactly ONCE by the user. [The
    		serial# is unaffected by this, i. e. it remains
    		read-only.]
    
    - Protected RAM:
    		CONFIG_PRAM
    
    		Define this variable to enable the reservation of
    		"protected RAM", i. e. RAM which is not overwritten
    		by U-Boot. Define CONFIG_PRAM to hold the number of
    		kB you want to reserve for pRAM. You can overwrite
    		this default value by defining an environment
    		variable "pram" to the number of kB you want to
    		reserve. Note that the board info structure will
    		still show the full amount of RAM. If pRAM is
    		reserved, a new environment variable "mem" will
    		automatically be defined to hold the amount of
    		remaining RAM in a form that can be passed as boot
    		argument to Linux, for instance like that:
    
    
    			setenv bootargs ... mem=\${mem}
    
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    			saveenv
    
    		This way you can tell Linux not to use this memory,
    		either, which results in a memory region that will
    		not be affected by reboots.
    
    		*WARNING* If your board configuration uses automatic
    		detection of the RAM size, you must make sure that
    		this memory test is non-destructive. So far, the
    		following board configurations are known to be
    		"pRAM-clean":
    
    			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
    			HERMES, IP860, RPXlite, LWMON, LANTEC,
    
    			FLAGADM, TQM8260
    
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    - Error Recovery:
    		CONFIG_PANIC_HANG
    
    		Define this variable to stop the system in case of a
    		fatal error, so that you have to reset it manually.
    		This is probably NOT a good idea for an embedded
    
    		system where you want the system to reboot
    
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    		automatically as fast as possible, but it may be
    		useful during development since you can try to debug
    		the conditions that lead to the situation.
    
    		CONFIG_NET_RETRY_COUNT
    
    
    		This variable defines the number of retries for
    		network operations like ARP, RARP, TFTP, or BOOTP
    		before giving up the operation. If not defined, a
    		default value of 5 is used.
    
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    		CONFIG_ARP_TIMEOUT
    
    		Timeout waiting for an ARP reply in milliseconds.
    
    
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    - Command Interpreter:
    
    
    		Enable auto completion of commands using TAB.
    
    
    		Note that this feature has NOT been implemented yet
    		for the "hush" shell.
    
    		CONFIG_SYS_HUSH_PARSER
    
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    		Define this variable to enable the "hush" shell (from
    		Busybox) as command line interpreter, thus enabling
    		powerful command line syntax like
    		if...then...else...fi conditionals or `&&' and '||'