xref: /rk3399_rockchip-uboot/README (revision f773bea8e11f4a11c388dcee956b2444203e6b65)
1#
2# (C) Copyright 2000 - 2005
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port.
55
56
57Where to get help:
58==================
59
60In case you have questions about, problems with or contributions for
61U-Boot you should send a message to the U-Boot mailing list at
62<u-boot-users@lists.sourceforge.net>. There is also an archive of
63previous traffic on the mailing list - please search the archive
64before asking FAQ's. Please see
65http://lists.sourceforge.net/lists/listinfo/u-boot-users/
66
67
68Where we come from:
69===================
70
71- start from 8xxrom sources
72- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73- clean up code
74- make it easier to add custom boards
75- make it possible to add other [PowerPC] CPUs
76- extend functions, especially:
77  * Provide extended interface to Linux boot loader
78  * S-Record download
79  * network boot
80  * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
81- create ARMBoot project (http://sourceforge.net/projects/armboot)
82- add other CPU families (starting with ARM)
83- create U-Boot project (http://sourceforge.net/projects/u-boot)
84
85
86Names and Spelling:
87===================
88
89The "official" name of this project is "Das U-Boot". The spelling
90"U-Boot" shall be used in all written text (documentation, comments
91in source files etc.). Example:
92
93	This is the README file for the U-Boot project.
94
95File names etc. shall be based on the string "u-boot". Examples:
96
97	include/asm-ppc/u-boot.h
98
99	#include <asm/u-boot.h>
100
101Variable names, preprocessor constants etc. shall be either based on
102the string "u_boot" or on "U_BOOT". Example:
103
104	U_BOOT_VERSION		u_boot_logo
105	IH_OS_U_BOOT		u_boot_hush_start
106
107
108Versioning:
109===========
110
111U-Boot uses a 3 level version number containing a version, a
112sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
113sub-version "34", and patchlevel "4".
114
115The patchlevel is used to indicate certain stages of development
116between released versions, i. e. officially released versions of
117U-Boot will always have a patchlevel of "0".
118
119
120Directory Hierarchy:
121====================
122
123- board		Board dependent files
124- common	Misc architecture independent functions
125- cpu		CPU specific files
126  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
127  - arm720t	Files specific to ARM 720 CPUs
128  - arm920t	Files specific to ARM 920 CPUs
129    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
130    - imx	Files specific to Freescale MC9328 i.MX CPUs
131    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
132  - arm925t	Files specific to ARM 925 CPUs
133  - arm926ejs	Files specific to ARM 926 CPUs
134  - arm1136	Files specific to ARM 1136 CPUs
135  - at32ap	Files specific to Atmel AVR32 AP CPUs
136  - i386	Files specific to i386 CPUs
137  - ixp		Files specific to Intel XScale IXP CPUs
138  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
139  - mcf5227x	Files specific to Freescale ColdFire MCF5227x CPUs
140  - mcf532x	Files specific to Freescale ColdFire MCF5329 CPUs
141  - mcf5445x	Files specific to Freescale ColdFire MCF5445x CPUs
142  - mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
143  - mips	Files specific to MIPS CPUs
144  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
145  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
146  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
147  - mpc8220	Files specific to Freescale MPC8220 CPUs
148  - mpc824x	Files specific to Freescale MPC824x CPUs
149  - mpc8260	Files specific to Freescale MPC8260 CPUs
150  - mpc85xx	Files specific to Freescale MPC85xx CPUs
151  - nios	Files specific to Altera NIOS CPUs
152  - nios2	Files specific to Altera Nios-II CPUs
153  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
154  - pxa		Files specific to Intel XScale PXA CPUs
155  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
156  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
157- disk		Code for disk drive partition handling
158- doc		Documentation (don't expect too much)
159- drivers	Commonly used device drivers
160- dtt		Digital Thermometer and Thermostat drivers
161- examples	Example code for standalone applications, etc.
162- include	Header Files
163- lib_arm	Files generic to ARM	 architecture
164- lib_avr32	Files generic to AVR32	 architecture
165- lib_generic	Files generic to all	 architectures
166- lib_i386	Files generic to i386	 architecture
167- lib_m68k	Files generic to m68k	 architecture
168- lib_mips	Files generic to MIPS	 architecture
169- lib_nios	Files generic to NIOS	 architecture
170- lib_ppc	Files generic to PowerPC architecture
171- libfdt 	Library files to support flattened device trees
172- net		Networking code
173- post		Power On Self Test
174- rtc		Real Time Clock drivers
175- tools		Tools to build S-Record or U-Boot images, etc.
176
177Software Configuration:
178=======================
179
180Configuration is usually done using C preprocessor defines; the
181rationale behind that is to avoid dead code whenever possible.
182
183There are two classes of configuration variables:
184
185* Configuration _OPTIONS_:
186  These are selectable by the user and have names beginning with
187  "CONFIG_".
188
189* Configuration _SETTINGS_:
190  These depend on the hardware etc. and should not be meddled with if
191  you don't know what you're doing; they have names beginning with
192  "CFG_".
193
194Later we will add a configuration tool - probably similar to or even
195identical to what's used for the Linux kernel. Right now, we have to
196do the configuration by hand, which means creating some symbolic
197links and editing some configuration files. We use the TQM8xxL boards
198as an example here.
199
200
201Selection of Processor Architecture and Board Type:
202---------------------------------------------------
203
204For all supported boards there are ready-to-use default
205configurations available; just type "make <board_name>_config".
206
207Example: For a TQM823L module type:
208
209	cd u-boot
210	make TQM823L_config
211
212For the Cogent platform, you need to specify the cpu type as well;
213e.g. "make cogent_mpc8xx_config". And also configure the cogent
214directory according to the instructions in cogent/README.
215
216
217Configuration Options:
218----------------------
219
220Configuration depends on the combination of board and CPU type; all
221such information is kept in a configuration file
222"include/configs/<board_name>.h".
223
224Example: For a TQM823L module, all configuration settings are in
225"include/configs/TQM823L.h".
226
227
228Many of the options are named exactly as the corresponding Linux
229kernel configuration options. The intention is to make it easier to
230build a config tool - later.
231
232
233The following options need to be configured:
234
235- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
236
237- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
238
239- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
240		Define exactly one, e.g. CONFIG_ATSTK1002
241
242- CPU Module Type: (if CONFIG_COGENT is defined)
243		Define exactly one of
244		CONFIG_CMA286_60_OLD
245--- FIXME --- not tested yet:
246		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
247		CONFIG_CMA287_23, CONFIG_CMA287_50
248
249- Motherboard Type: (if CONFIG_COGENT is defined)
250		Define exactly one of
251		CONFIG_CMA101, CONFIG_CMA102
252
253- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
254		Define one or more of
255		CONFIG_CMA302
256
257- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
258		Define one or more of
259		CONFIG_LCD_HEARTBEAT	- update a character position on
260					  the lcd display every second with
261					  a "rotator" |\-/|\-/
262
263- Board flavour: (if CONFIG_MPC8260ADS is defined)
264		CONFIG_ADSTYPE
265		Possible values are:
266			CFG_8260ADS	- original MPC8260ADS
267			CFG_8266ADS	- MPC8266ADS
268			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
269			CFG_8272ADS	- MPC8272ADS
270
271- MPC824X Family Member (if CONFIG_MPC824X is defined)
272		Define exactly one of
273		CONFIG_MPC8240, CONFIG_MPC8245
274
275- 8xx CPU Options: (if using an MPC8xx cpu)
276		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
277					  get_gclk_freq() cannot work
278					  e.g. if there is no 32KHz
279					  reference PIT/RTC clock
280		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
281					  or XTAL/EXTAL)
282
283- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
284		CFG_8xx_CPUCLK_MIN
285		CFG_8xx_CPUCLK_MAX
286		CONFIG_8xx_CPUCLK_DEFAULT
287			See doc/README.MPC866
288
289		CFG_MEASURE_CPUCLK
290
291		Define this to measure the actual CPU clock instead
292		of relying on the correctness of the configured
293		values. Mostly useful for board bringup to make sure
294		the PLL is locked at the intended frequency. Note
295		that this requires a (stable) reference clock (32 kHz
296		RTC clock or CFG_8XX_XIN)
297
298- Intel Monahans options:
299		CFG_MONAHANS_RUN_MODE_OSC_RATIO
300
301		Defines the Monahans run mode to oscillator
302		ratio. Valid values are 8, 16, 24, 31. The core
303		frequency is this value multiplied by 13 MHz.
304
305		CFG_MONAHANS_TURBO_RUN_MODE_RATIO
306
307		Defines the Monahans turbo mode to oscillator
308		ratio. Valid values are 1 (default if undefined) and
309		2. The core frequency as calculated above is multiplied
310		by this value.
311
312- Linux Kernel Interface:
313		CONFIG_CLOCKS_IN_MHZ
314
315		U-Boot stores all clock information in Hz
316		internally. For binary compatibility with older Linux
317		kernels (which expect the clocks passed in the
318		bd_info data to be in MHz) the environment variable
319		"clocks_in_mhz" can be defined so that U-Boot
320		converts clock data to MHZ before passing it to the
321		Linux kernel.
322		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
323		"clocks_in_mhz=1" is  automatically  included  in  the
324		default environment.
325
326		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
327
328		When transfering memsize parameter to linux, some versions
329		expect it to be in bytes, others in MB.
330		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
331
332		CONFIG_OF_LIBFDT / CONFIG_OF_FLAT_TREE
333
334		New kernel versions are expecting firmware settings to be
335		passed using flattened device trees (based on open firmware
336		concepts).
337
338		CONFIG_OF_LIBFDT
339		 * New libfdt-based support
340		 * Adds the "fdt" command
341		 * The bootm command automatically updates the fdt
342
343		CONFIG_OF_FLAT_TREE
344		 * Deprecated, see CONFIG_OF_LIBFDT
345		 * Original ft_build.c-based support
346		 * Automatically modifies the dft as part of the bootm command
347		 * The environment variable "disable_of", when set,
348		     disables this functionality.
349
350		OF_CPU - The proper name of the cpus node.
351		OF_SOC - The proper name of the soc node.
352		OF_TBCLK - The timebase frequency.
353		OF_STDOUT_PATH - The path to the console device
354
355		boards with QUICC Engines require OF_QE to set UCC mac addresses
356
357		CONFIG_OF_HAS_BD_T
358
359		 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
360		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
361		     will have a copy of the bd_t.  Space should be
362		     pre-allocated in the dts for the bd_t.
363
364		CONFIG_OF_HAS_UBOOT_ENV
365
366		 * CONFIG_OF_LIBFDT - enables the "fdt env" command
367		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
368		     will have a copy of u-boot's environment variables
369
370		CONFIG_OF_BOARD_SETUP
371
372		Board code has addition modification that it wants to make
373		to the flat device tree before handing it off to the kernel
374
375		CONFIG_OF_BOOT_CPU
376
377		This define fills in the correct boot cpu in the boot
378		param header, the default value is zero if undefined.
379
380- Serial Ports:
381		CFG_PL010_SERIAL
382
383		Define this if you want support for Amba PrimeCell PL010 UARTs.
384
385		CFG_PL011_SERIAL
386
387		Define this if you want support for Amba PrimeCell PL011 UARTs.
388
389		CONFIG_PL011_CLOCK
390
391		If you have Amba PrimeCell PL011 UARTs, set this variable to
392		the clock speed of the UARTs.
393
394		CONFIG_PL01x_PORTS
395
396		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
397		define this to a list of base addresses for each (supported)
398		port. See e.g. include/configs/versatile.h
399
400
401- Console Interface:
402		Depending on board, define exactly one serial port
403		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
404		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
405		console by defining CONFIG_8xx_CONS_NONE
406
407		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
408		port routines must be defined elsewhere
409		(i.e. serial_init(), serial_getc(), ...)
410
411		CONFIG_CFB_CONSOLE
412		Enables console device for a color framebuffer. Needs following
413		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
414			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
415						(default big endian)
416			VIDEO_HW_RECTFILL	graphic chip supports
417						rectangle fill
418						(cf. smiLynxEM)
419			VIDEO_HW_BITBLT		graphic chip supports
420						bit-blit (cf. smiLynxEM)
421			VIDEO_VISIBLE_COLS	visible pixel columns
422						(cols=pitch)
423			VIDEO_VISIBLE_ROWS	visible pixel rows
424			VIDEO_PIXEL_SIZE	bytes per pixel
425			VIDEO_DATA_FORMAT	graphic data format
426						(0-5, cf. cfb_console.c)
427			VIDEO_FB_ADRS		framebuffer address
428			VIDEO_KBD_INIT_FCT	keyboard int fct
429						(i.e. i8042_kbd_init())
430			VIDEO_TSTC_FCT		test char fct
431						(i.e. i8042_tstc)
432			VIDEO_GETC_FCT		get char fct
433						(i.e. i8042_getc)
434			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
435						(requires blink timer
436						cf. i8042.c)
437			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
438			CONFIG_CONSOLE_TIME	display time/date info in
439						upper right corner
440						(requires CONFIG_CMD_DATE)
441			CONFIG_VIDEO_LOGO	display Linux logo in
442						upper left corner
443			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
444						linux_logo.h for logo.
445						Requires CONFIG_VIDEO_LOGO
446			CONFIG_CONSOLE_EXTRA_INFO
447						addional board info beside
448						the logo
449
450		When CONFIG_CFB_CONSOLE is defined, video console is
451		default i/o. Serial console can be forced with
452		environment 'console=serial'.
453
454		When CONFIG_SILENT_CONSOLE is defined, all console
455		messages (by U-Boot and Linux!) can be silenced with
456		the "silent" environment variable. See
457		doc/README.silent for more information.
458
459- Console Baudrate:
460		CONFIG_BAUDRATE - in bps
461		Select one of the baudrates listed in
462		CFG_BAUDRATE_TABLE, see below.
463		CFG_BRGCLK_PRESCALE, baudrate prescale
464
465- Interrupt driven serial port input:
466		CONFIG_SERIAL_SOFTWARE_FIFO
467
468		PPC405GP only.
469		Use an interrupt handler for receiving data on the
470		serial port. It also enables using hardware handshake
471		(RTS/CTS) and UART's built-in FIFO. Set the number of
472		bytes the interrupt driven input buffer should have.
473
474		Leave undefined to disable this feature, including
475		disable the buffer and hardware handshake.
476
477- Console UART Number:
478		CONFIG_UART1_CONSOLE
479
480		AMCC PPC4xx only.
481		If defined internal UART1 (and not UART0) is used
482		as default U-Boot console.
483
484- Boot Delay:	CONFIG_BOOTDELAY - in seconds
485		Delay before automatically booting the default image;
486		set to -1 to disable autoboot.
487
488		See doc/README.autoboot for these options that
489		work with CONFIG_BOOTDELAY. None are required.
490		CONFIG_BOOT_RETRY_TIME
491		CONFIG_BOOT_RETRY_MIN
492		CONFIG_AUTOBOOT_KEYED
493		CONFIG_AUTOBOOT_PROMPT
494		CONFIG_AUTOBOOT_DELAY_STR
495		CONFIG_AUTOBOOT_STOP_STR
496		CONFIG_AUTOBOOT_DELAY_STR2
497		CONFIG_AUTOBOOT_STOP_STR2
498		CONFIG_ZERO_BOOTDELAY_CHECK
499		CONFIG_RESET_TO_RETRY
500
501- Autoboot Command:
502		CONFIG_BOOTCOMMAND
503		Only needed when CONFIG_BOOTDELAY is enabled;
504		define a command string that is automatically executed
505		when no character is read on the console interface
506		within "Boot Delay" after reset.
507
508		CONFIG_BOOTARGS
509		This can be used to pass arguments to the bootm
510		command. The value of CONFIG_BOOTARGS goes into the
511		environment value "bootargs".
512
513		CONFIG_RAMBOOT and CONFIG_NFSBOOT
514		The value of these goes into the environment as
515		"ramboot" and "nfsboot" respectively, and can be used
516		as a convenience, when switching between booting from
517		ram and nfs.
518
519- Pre-Boot Commands:
520		CONFIG_PREBOOT
521
522		When this option is #defined, the existence of the
523		environment variable "preboot" will be checked
524		immediately before starting the CONFIG_BOOTDELAY
525		countdown and/or running the auto-boot command resp.
526		entering interactive mode.
527
528		This feature is especially useful when "preboot" is
529		automatically generated or modified. For an example
530		see the LWMON board specific code: here "preboot" is
531		modified when the user holds down a certain
532		combination of keys on the (special) keyboard when
533		booting the systems
534
535- Serial Download Echo Mode:
536		CONFIG_LOADS_ECHO
537		If defined to 1, all characters received during a
538		serial download (using the "loads" command) are
539		echoed back. This might be needed by some terminal
540		emulations (like "cu"), but may as well just take
541		time on others. This setting #define's the initial
542		value of the "loads_echo" environment variable.
543
544- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
545		CONFIG_KGDB_BAUDRATE
546		Select one of the baudrates listed in
547		CFG_BAUDRATE_TABLE, see below.
548
549- Monitor Functions:
550		Monitor commands can be included or excluded
551		from the build by using the #include files
552		"config_cmd_all.h" and #undef'ing unwanted
553		commands, or using "config_cmd_default.h"
554		and augmenting with additional #define's
555		for wanted commands.
556
557		The default command configuration includes all commands
558		except those marked below with a "*".
559
560		CONFIG_CMD_ASKENV	* ask for env variable
561		CONFIG_CMD_AUTOSCRIPT	  Autoscript Support
562		CONFIG_CMD_BDI		  bdinfo
563		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
564		CONFIG_CMD_BMP		* BMP support
565		CONFIG_CMD_BSP		* Board specific commands
566		CONFIG_CMD_BOOTD	  bootd
567		CONFIG_CMD_CACHE	* icache, dcache
568		CONFIG_CMD_CONSOLE	  coninfo
569		CONFIG_CMD_DATE		* support for RTC, date/time...
570		CONFIG_CMD_DHCP		* DHCP support
571		CONFIG_CMD_DIAG		* Diagnostics
572		CONFIG_CMD_DOC		* Disk-On-Chip Support
573		CONFIG_CMD_DTT		* Digital Therm and Thermostat
574		CONFIG_CMD_ECHO		  echo arguments
575		CONFIG_CMD_EEPROM	* EEPROM read/write support
576		CONFIG_CMD_ELF		* bootelf, bootvx
577		CONFIG_CMD_ENV		  saveenv
578		CONFIG_CMD_FDC		* Floppy Disk Support
579		CONFIG_CMD_FAT		* FAT partition support
580		CONFIG_CMD_FDOS		* Dos diskette Support
581		CONFIG_CMD_FLASH	  flinfo, erase, protect
582		CONFIG_CMD_FPGA		  FPGA device initialization support
583		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
584		CONFIG_CMD_I2C		* I2C serial bus support
585		CONFIG_CMD_IDE		* IDE harddisk support
586		CONFIG_CMD_IMI		  iminfo
587		CONFIG_CMD_IMLS		  List all found images
588		CONFIG_CMD_IMMAP	* IMMR dump support
589		CONFIG_CMD_IRQ		* irqinfo
590		CONFIG_CMD_ITEST	  Integer/string test of 2 values
591		CONFIG_CMD_JFFS2	* JFFS2 Support
592		CONFIG_CMD_KGDB		* kgdb
593		CONFIG_CMD_LOADB	  loadb
594		CONFIG_CMD_LOADS	  loads
595		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
596					  loop, loopw, mtest
597		CONFIG_CMD_MISC		  Misc functions like sleep etc
598		CONFIG_CMD_MMC		* MMC memory mapped support
599		CONFIG_CMD_MII		* MII utility commands
600		CONFIG_CMD_NAND		* NAND support
601		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
602		CONFIG_CMD_PCI		* pciinfo
603		CONFIG_CMD_PCMCIA		* PCMCIA support
604		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
605					  host
606		CONFIG_CMD_PORTIO	* Port I/O
607		CONFIG_CMD_REGINFO	* Register dump
608		CONFIG_CMD_RUN		  run command in env variable
609		CONFIG_CMD_SAVES	* save S record dump
610		CONFIG_CMD_SCSI		* SCSI Support
611		CONFIG_CMD_SDRAM	* print SDRAM configuration information
612					  (requires CONFIG_CMD_I2C)
613		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
614					  (4xx only)
615		CONFIG_CMD_SPI		* SPI serial bus support
616		CONFIG_CMD_USB		* USB support
617		CONFIG_CMD_VFD		* VFD support (TRAB)
618		CONFIG_CMD_BSP		* Board SPecific functions
619		CONFIG_CMD_CDP		* Cisco Discover Protocol support
620		CONFIG_CMD_FSL		* Microblaze FSL support
621
622
623		EXAMPLE: If you want all functions except of network
624		support you can write:
625
626		#include "config_cmd_all.h"
627		#undef CONFIG_CMD_NET
628
629	Other Commands:
630		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
631
632	Note:	Don't enable the "icache" and "dcache" commands
633		(configuration option CONFIG_CMD_CACHE) unless you know
634		what you (and your U-Boot users) are doing. Data
635		cache cannot be enabled on systems like the 8xx or
636		8260 (where accesses to the IMMR region must be
637		uncached), and it cannot be disabled on all other
638		systems where we (mis-) use the data cache to hold an
639		initial stack and some data.
640
641
642		XXX - this list needs to get updated!
643
644- Watchdog:
645		CONFIG_WATCHDOG
646		If this variable is defined, it enables watchdog
647		support. There must be support in the platform specific
648		code for a watchdog. For the 8xx and 8260 CPUs, the
649		SIU Watchdog feature is enabled in the SYPCR
650		register.
651
652- U-Boot Version:
653		CONFIG_VERSION_VARIABLE
654		If this variable is defined, an environment variable
655		named "ver" is created by U-Boot showing the U-Boot
656		version as printed by the "version" command.
657		This variable is readonly.
658
659- Real-Time Clock:
660
661		When CONFIG_CMD_DATE is selected, the type of the RTC
662		has to be selected, too. Define exactly one of the
663		following options:
664
665		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
666		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
667		CONFIG_RTC_MC146818	- use MC146818 RTC
668		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
669		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
670		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
671		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
672		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
673
674		Note that if the RTC uses I2C, then the I2C interface
675		must also be configured. See I2C Support, below.
676
677- Timestamp Support:
678
679		When CONFIG_TIMESTAMP is selected, the timestamp
680		(date and time) of an image is printed by image
681		commands like bootm or iminfo. This option is
682		automatically enabled when you select CONFIG_CMD_DATE .
683
684- Partition Support:
685		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
686		and/or CONFIG_ISO_PARTITION
687
688		If IDE or SCSI support	is  enabled  (CONFIG_CMD_IDE or
689		CONFIG_CMD_SCSI) you must configure support for at least
690		one partition type as well.
691
692- IDE Reset method:
693		CONFIG_IDE_RESET_ROUTINE - this is defined in several
694		board configurations files but used nowhere!
695
696		CONFIG_IDE_RESET - is this is defined, IDE Reset will
697		be performed by calling the function
698			ide_set_reset(int reset)
699		which has to be defined in a board specific file
700
701- ATAPI Support:
702		CONFIG_ATAPI
703
704		Set this to enable ATAPI support.
705
706- LBA48 Support
707		CONFIG_LBA48
708
709		Set this to enable support for disks larger than 137GB
710		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
711		Whithout these , LBA48 support uses 32bit variables and will 'only'
712		support disks up to 2.1TB.
713
714		CFG_64BIT_LBA:
715			When enabled, makes the IDE subsystem use 64bit sector addresses.
716			Default is 32bit.
717
718- SCSI Support:
719		At the moment only there is only support for the
720		SYM53C8XX SCSI controller; define
721		CONFIG_SCSI_SYM53C8XX to enable it.
722
723		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
724		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
725		CFG_SCSI_MAX_LUN] can be adjusted to define the
726		maximum numbers of LUNs, SCSI ID's and target
727		devices.
728		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
729
730- NETWORK Support (PCI):
731		CONFIG_E1000
732		Support for Intel 8254x gigabit chips.
733
734		CONFIG_EEPRO100
735		Support for Intel 82557/82559/82559ER chips.
736		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
737		write routine for first time initialisation.
738
739		CONFIG_TULIP
740		Support for Digital 2114x chips.
741		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
742		modem chip initialisation (KS8761/QS6611).
743
744		CONFIG_NATSEMI
745		Support for National dp83815 chips.
746
747		CONFIG_NS8382X
748		Support for National dp8382[01] gigabit chips.
749
750- NETWORK Support (other):
751
752		CONFIG_DRIVER_LAN91C96
753		Support for SMSC's LAN91C96 chips.
754
755			CONFIG_LAN91C96_BASE
756			Define this to hold the physical address
757			of the LAN91C96's I/O space
758
759			CONFIG_LAN91C96_USE_32_BIT
760			Define this to enable 32 bit addressing
761
762		CONFIG_DRIVER_SMC91111
763		Support for SMSC's LAN91C111 chip
764
765			CONFIG_SMC91111_BASE
766			Define this to hold the physical address
767			of the device (I/O space)
768
769			CONFIG_SMC_USE_32_BIT
770			Define this if data bus is 32 bits
771
772			CONFIG_SMC_USE_IOFUNCS
773			Define this to use i/o functions instead of macros
774			(some hardware wont work with macros)
775
776- USB Support:
777		At the moment only the UHCI host controller is
778		supported (PIP405, MIP405, MPC5200); define
779		CONFIG_USB_UHCI to enable it.
780		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
781		and define CONFIG_USB_STORAGE to enable the USB
782		storage devices.
783		Note:
784		Supported are USB Keyboards and USB Floppy drives
785		(TEAC FD-05PUB).
786		MPC5200 USB requires additional defines:
787			CONFIG_USB_CLOCK
788				for 528 MHz Clock: 0x0001bbbb
789			CONFIG_USB_CONFIG
790				for differential drivers: 0x00001000
791				for single ended drivers: 0x00005000
792			CFG_USB_EVENT_POLL
793				May be defined to allow interrupt polling
794				instead of using asynchronous interrupts
795
796- USB Device:
797		Define the below if you wish to use the USB console.
798		Once firmware is rebuilt from a serial console issue the
799		command "setenv stdin usbtty; setenv stdout usbtty" and
800		attach your usb cable. The Unix command "dmesg" should print
801		it has found a new device. The environment variable usbtty
802		can be set to gserial or cdc_acm to enable your device to
803		appear to a USB host as a Linux gserial device or a
804		Common Device Class Abstract Control Model serial device.
805		If you select usbtty = gserial you should be able to enumerate
806		a Linux host by
807		# modprobe usbserial vendor=0xVendorID product=0xProductID
808		else if using cdc_acm, simply setting the environment
809		variable usbtty to be cdc_acm should suffice. The following
810		might be defined in YourBoardName.h
811
812			CONFIG_USB_DEVICE
813			Define this to build a UDC device
814
815			CONFIG_USB_TTY
816			Define this to have a tty type of device available to
817			talk to the UDC device
818
819			CFG_CONSOLE_IS_IN_ENV
820			Define this if you want stdin, stdout &/or stderr to
821			be set to usbtty.
822
823			mpc8xx:
824				CFG_USB_EXTC_CLK 0xBLAH
825				Derive USB clock from external clock "blah"
826				- CFG_USB_EXTC_CLK 0x02
827
828				CFG_USB_BRG_CLK 0xBLAH
829				Derive USB clock from brgclk
830				- CFG_USB_BRG_CLK 0x04
831
832		If you have a USB-IF assigned VendorID then you may wish to
833		define your own vendor specific values either in BoardName.h
834		or directly in usbd_vendor_info.h. If you don't define
835		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
836		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
837		should pretend to be a Linux device to it's target host.
838
839			CONFIG_USBD_MANUFACTURER
840			Define this string as the name of your company for
841			- CONFIG_USBD_MANUFACTURER "my company"
842
843			CONFIG_USBD_PRODUCT_NAME
844			Define this string as the name of your product
845			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
846
847			CONFIG_USBD_VENDORID
848			Define this as your assigned Vendor ID from the USB
849			Implementors Forum. This *must* be a genuine Vendor ID
850			to avoid polluting the USB namespace.
851			- CONFIG_USBD_VENDORID 0xFFFF
852
853			CONFIG_USBD_PRODUCTID
854			Define this as the unique Product ID
855			for your device
856			- CONFIG_USBD_PRODUCTID 0xFFFF
857
858
859- MMC Support:
860		The MMC controller on the Intel PXA is supported. To
861		enable this define CONFIG_MMC. The MMC can be
862		accessed from the boot prompt by mapping the device
863		to physical memory similar to flash. Command line is
864		enabled with CONFIG_CMD_MMC. The MMC driver also works with
865		the FAT fs. This is enabled with CONFIG_CMD_FAT.
866
867- Journaling Flash filesystem support:
868		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
869		CONFIG_JFFS2_NAND_DEV
870		Define these for a default partition on a NAND device
871
872		CFG_JFFS2_FIRST_SECTOR,
873		CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
874		Define these for a default partition on a NOR device
875
876		CFG_JFFS_CUSTOM_PART
877		Define this to create an own partition. You have to provide a
878		function struct part_info* jffs2_part_info(int part_num)
879
880		If you define only one JFFS2 partition you may also want to
881		#define CFG_JFFS_SINGLE_PART	1
882		to disable the command chpart. This is the default when you
883		have not defined a custom partition
884
885- Keyboard Support:
886		CONFIG_ISA_KEYBOARD
887
888		Define this to enable standard (PC-Style) keyboard
889		support
890
891		CONFIG_I8042_KBD
892		Standard PC keyboard driver with US (is default) and
893		GERMAN key layout (switch via environment 'keymap=de') support.
894		Export function i8042_kbd_init, i8042_tstc and i8042_getc
895		for cfb_console. Supports cursor blinking.
896
897- Video support:
898		CONFIG_VIDEO
899
900		Define this to enable video support (for output to
901		video).
902
903		CONFIG_VIDEO_CT69000
904
905		Enable Chips & Technologies 69000 Video chip
906
907		CONFIG_VIDEO_SMI_LYNXEM
908		Enable Silicon Motion SMI 712/710/810 Video chip. The
909		video output is selected via environment 'videoout'
910		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
911		assumed.
912
913		For the CT69000 and SMI_LYNXEM drivers, videomode is
914		selected via environment 'videomode'. Two diferent ways
915		are possible:
916		- "videomode=num"   'num' is a standard LiLo mode numbers.
917		Following standard modes are supported	(* is default):
918
919		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
920		-------------+---------------------------------------------
921		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
922		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
923		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
924		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
925		-------------+---------------------------------------------
926		(i.e. setenv videomode 317; saveenv; reset;)
927
928		- "videomode=bootargs" all the video parameters are parsed
929		from the bootargs. (See drivers/video/videomodes.c)
930
931
932		CONFIG_VIDEO_SED13806
933		Enable Epson SED13806 driver. This driver supports 8bpp
934		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
935		or CONFIG_VIDEO_SED13806_16BPP
936
937- Keyboard Support:
938		CONFIG_KEYBOARD
939
940		Define this to enable a custom keyboard support.
941		This simply calls drv_keyboard_init() which must be
942		defined in your board-specific files.
943		The only board using this so far is RBC823.
944
945- LCD Support:	CONFIG_LCD
946
947		Define this to enable LCD support (for output to LCD
948		display); also select one of the supported displays
949		by defining one of these:
950
951		CONFIG_NEC_NL6448AC33:
952
953			NEC NL6448AC33-18. Active, color, single scan.
954
955		CONFIG_NEC_NL6448BC20
956
957			NEC NL6448BC20-08. 6.5", 640x480.
958			Active, color, single scan.
959
960		CONFIG_NEC_NL6448BC33_54
961
962			NEC NL6448BC33-54. 10.4", 640x480.
963			Active, color, single scan.
964
965		CONFIG_SHARP_16x9
966
967			Sharp 320x240. Active, color, single scan.
968			It isn't 16x9, and I am not sure what it is.
969
970		CONFIG_SHARP_LQ64D341
971
972			Sharp LQ64D341 display, 640x480.
973			Active, color, single scan.
974
975		CONFIG_HLD1045
976
977			HLD1045 display, 640x480.
978			Active, color, single scan.
979
980		CONFIG_OPTREX_BW
981
982			Optrex	 CBL50840-2 NF-FW 99 22 M5
983			or
984			Hitachi	 LMG6912RPFC-00T
985			or
986			Hitachi	 SP14Q002
987
988			320x240. Black & white.
989
990		Normally display is black on white background; define
991		CFG_WHITE_ON_BLACK to get it inverted.
992
993- Splash Screen Support: CONFIG_SPLASH_SCREEN
994
995		If this option is set, the environment is checked for
996		a variable "splashimage". If found, the usual display
997		of logo, copyright and system information on the LCD
998		is suppressed and the BMP image at the address
999		specified in "splashimage" is loaded instead. The
1000		console is redirected to the "nulldev", too. This
1001		allows for a "silent" boot where a splash screen is
1002		loaded very quickly after power-on.
1003
1004- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1005
1006		If this option is set, additionally to standard BMP
1007		images, gzipped BMP images can be displayed via the
1008		splashscreen support or the bmp command.
1009
1010- Compression support:
1011		CONFIG_BZIP2
1012
1013		If this option is set, support for bzip2 compressed
1014		images is included. If not, only uncompressed and gzip
1015		compressed images are supported.
1016
1017		NOTE: the bzip2 algorithm requires a lot of RAM, so
1018		the malloc area (as defined by CFG_MALLOC_LEN) should
1019		be at least 4MB.
1020
1021- MII/PHY support:
1022		CONFIG_PHY_ADDR
1023
1024		The address of PHY on MII bus.
1025
1026		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1027
1028		The clock frequency of the MII bus
1029
1030		CONFIG_PHY_GIGE
1031
1032		If this option is set, support for speed/duplex
1033		detection of Gigabit PHY is included.
1034
1035		CONFIG_PHY_RESET_DELAY
1036
1037		Some PHY like Intel LXT971A need extra delay after
1038		reset before any MII register access is possible.
1039		For such PHY, set this option to the usec delay
1040		required. (minimum 300usec for LXT971A)
1041
1042		CONFIG_PHY_CMD_DELAY (ppc4xx)
1043
1044		Some PHY like Intel LXT971A need extra delay after
1045		command issued before MII status register can be read
1046
1047- Ethernet address:
1048		CONFIG_ETHADDR
1049		CONFIG_ETH2ADDR
1050		CONFIG_ETH3ADDR
1051
1052		Define a default value for ethernet address to use
1053		for the respective ethernet interface, in case this
1054		is not determined automatically.
1055
1056- IP address:
1057		CONFIG_IPADDR
1058
1059		Define a default value for the IP address to use for
1060		the default ethernet interface, in case this is not
1061		determined through e.g. bootp.
1062
1063- Server IP address:
1064		CONFIG_SERVERIP
1065
1066		Defines a default value for theIP address of a TFTP
1067		server to contact when using the "tftboot" command.
1068
1069- Multicast TFTP Mode:
1070		CONFIG_MCAST_TFTP
1071
1072		Defines whether you want to support multicast TFTP as per
1073		rfc-2090; for example to work with atftp.  Lets lots of targets
1074		tftp down the same boot image concurrently.  Note: the ethernet
1075		driver in use must provide a function: mcast() to join/leave a
1076		multicast group.
1077
1078		CONFIG_BOOTP_RANDOM_DELAY
1079- BOOTP Recovery Mode:
1080		CONFIG_BOOTP_RANDOM_DELAY
1081
1082		If you have many targets in a network that try to
1083		boot using BOOTP, you may want to avoid that all
1084		systems send out BOOTP requests at precisely the same
1085		moment (which would happen for instance at recovery
1086		from a power failure, when all systems will try to
1087		boot, thus flooding the BOOTP server. Defining
1088		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1089		inserted before sending out BOOTP requests. The
1090		following delays are inserted then:
1091
1092		1st BOOTP request:	delay 0 ... 1 sec
1093		2nd BOOTP request:	delay 0 ... 2 sec
1094		3rd BOOTP request:	delay 0 ... 4 sec
1095		4th and following
1096		BOOTP requests:		delay 0 ... 8 sec
1097
1098- DHCP Advanced Options:
1099		You can fine tune the DHCP functionality by defining
1100		CONFIG_BOOTP_* symbols:
1101
1102		CONFIG_BOOTP_SUBNETMASK
1103		CONFIG_BOOTP_GATEWAY
1104		CONFIG_BOOTP_HOSTNAME
1105		CONFIG_BOOTP_NISDOMAIN
1106		CONFIG_BOOTP_BOOTPATH
1107		CONFIG_BOOTP_BOOTFILESIZE
1108		CONFIG_BOOTP_DNS
1109		CONFIG_BOOTP_DNS2
1110		CONFIG_BOOTP_SEND_HOSTNAME
1111		CONFIG_BOOTP_NTPSERVER
1112		CONFIG_BOOTP_TIMEOFFSET
1113		CONFIG_BOOTP_VENDOREX
1114
1115		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1116		environment variable, not the BOOTP server.
1117
1118		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1119		serverip from a DHCP server, it is possible that more
1120		than one DNS serverip is offered to the client.
1121		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1122		serverip will be stored in the additional environment
1123		variable "dnsip2". The first DNS serverip is always
1124		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1125		is defined.
1126
1127		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1128		to do a dynamic update of a DNS server. To do this, they
1129		need the hostname of the DHCP requester.
1130		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1131		of the "hostname" environment variable is passed as
1132		option 12 to the DHCP server.
1133
1134 - CDP Options:
1135		CONFIG_CDP_DEVICE_ID
1136
1137		The device id used in CDP trigger frames.
1138
1139		CONFIG_CDP_DEVICE_ID_PREFIX
1140
1141		A two character string which is prefixed to the MAC address
1142		of the device.
1143
1144		CONFIG_CDP_PORT_ID
1145
1146		A printf format string which contains the ascii name of
1147		the port. Normally is set to "eth%d" which sets
1148		eth0 for the first ethernet, eth1 for the second etc.
1149
1150		CONFIG_CDP_CAPABILITIES
1151
1152		A 32bit integer which indicates the device capabilities;
1153		0x00000010 for a normal host which does not forwards.
1154
1155		CONFIG_CDP_VERSION
1156
1157		An ascii string containing the version of the software.
1158
1159		CONFIG_CDP_PLATFORM
1160
1161		An ascii string containing the name of the platform.
1162
1163		CONFIG_CDP_TRIGGER
1164
1165		A 32bit integer sent on the trigger.
1166
1167		CONFIG_CDP_POWER_CONSUMPTION
1168
1169		A 16bit integer containing the power consumption of the
1170		device in .1 of milliwatts.
1171
1172		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1173
1174		A byte containing the id of the VLAN.
1175
1176- Status LED:	CONFIG_STATUS_LED
1177
1178		Several configurations allow to display the current
1179		status using a LED. For instance, the LED will blink
1180		fast while running U-Boot code, stop blinking as
1181		soon as a reply to a BOOTP request was received, and
1182		start blinking slow once the Linux kernel is running
1183		(supported by a status LED driver in the Linux
1184		kernel). Defining CONFIG_STATUS_LED enables this
1185		feature in U-Boot.
1186
1187- CAN Support:	CONFIG_CAN_DRIVER
1188
1189		Defining CONFIG_CAN_DRIVER enables CAN driver support
1190		on those systems that support this (optional)
1191		feature, like the TQM8xxL modules.
1192
1193- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1194
1195		These enable I2C serial bus commands. Defining either of
1196		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1197		include the appropriate I2C driver for the selected cpu.
1198
1199		This will allow you to use i2c commands at the u-boot
1200		command line (as long as you set CONFIG_CMD_I2C in
1201		CONFIG_COMMANDS) and communicate with i2c based realtime
1202		clock chips. See common/cmd_i2c.c for a description of the
1203		command line interface.
1204
1205		CONFIG_I2C_CMD_TREE is a recommended option that places
1206		all I2C commands under a single 'i2c' root command.  The
1207		older 'imm', 'imd', 'iprobe' etc. commands are considered
1208		deprecated and may disappear in the future.
1209
1210		CONFIG_HARD_I2C selects a hardware I2C controller.
1211
1212		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1213		bit-banging) driver instead of CPM or similar hardware
1214		support for I2C.
1215
1216		There are several other quantities that must also be
1217		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1218
1219		In both cases you will need to define CFG_I2C_SPEED
1220		to be the frequency (in Hz) at which you wish your i2c bus
1221		to run and CFG_I2C_SLAVE to be the address of this node (ie
1222		the cpu's i2c node address).
1223
1224		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1225		sets the cpu up as a master node and so its address should
1226		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1227		p.16-473). So, set CFG_I2C_SLAVE to 0.
1228
1229		That's all that's required for CONFIG_HARD_I2C.
1230
1231		If you use the software i2c interface (CONFIG_SOFT_I2C)
1232		then the following macros need to be defined (examples are
1233		from include/configs/lwmon.h):
1234
1235		I2C_INIT
1236
1237		(Optional). Any commands necessary to enable the I2C
1238		controller or configure ports.
1239
1240		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1241
1242		I2C_PORT
1243
1244		(Only for MPC8260 CPU). The I/O port to use (the code
1245		assumes both bits are on the same port). Valid values
1246		are 0..3 for ports A..D.
1247
1248		I2C_ACTIVE
1249
1250		The code necessary to make the I2C data line active
1251		(driven).  If the data line is open collector, this
1252		define can be null.
1253
1254		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1255
1256		I2C_TRISTATE
1257
1258		The code necessary to make the I2C data line tri-stated
1259		(inactive).  If the data line is open collector, this
1260		define can be null.
1261
1262		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1263
1264		I2C_READ
1265
1266		Code that returns TRUE if the I2C data line is high,
1267		FALSE if it is low.
1268
1269		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1270
1271		I2C_SDA(bit)
1272
1273		If <bit> is TRUE, sets the I2C data line high. If it
1274		is FALSE, it clears it (low).
1275
1276		eg: #define I2C_SDA(bit) \
1277			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1278			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1279
1280		I2C_SCL(bit)
1281
1282		If <bit> is TRUE, sets the I2C clock line high. If it
1283		is FALSE, it clears it (low).
1284
1285		eg: #define I2C_SCL(bit) \
1286			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1287			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1288
1289		I2C_DELAY
1290
1291		This delay is invoked four times per clock cycle so this
1292		controls the rate of data transfer.  The data rate thus
1293		is 1 / (I2C_DELAY * 4). Often defined to be something
1294		like:
1295
1296		#define I2C_DELAY  udelay(2)
1297
1298		CFG_I2C_INIT_BOARD
1299
1300		When a board is reset during an i2c bus transfer
1301		chips might think that the current transfer is still
1302		in progress. On some boards it is possible to access
1303		the i2c SCLK line directly, either by using the
1304		processor pin as a GPIO or by having a second pin
1305		connected to the bus. If this option is defined a
1306		custom i2c_init_board() routine in boards/xxx/board.c
1307		is run early in the boot sequence.
1308
1309		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1310
1311		This option enables configuration of bi_iic_fast[] flags
1312		in u-boot bd_info structure based on u-boot environment
1313		variable "i2cfast". (see also i2cfast)
1314
1315		CONFIG_I2C_MULTI_BUS
1316
1317		This option allows the use of multiple I2C buses, each of which
1318		must have a controller.  At any point in time, only one bus is
1319		active.  To switch to a different bus, use the 'i2c dev' command.
1320		Note that bus numbering is zero-based.
1321
1322		CFG_I2C_NOPROBES
1323
1324		This option specifies a list of I2C devices that will be skipped
1325		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1326		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1327		pairs.  Otherwise, specify a 1D array of device addresses
1328
1329		e.g.
1330			#undef	CONFIG_I2C_MULTI_BUS
1331			#define CFG_I2C_NOPROBES	{0x50,0x68}
1332
1333		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1334
1335			#define	CONFIG_I2C_MULTI_BUS
1336			#define CFG_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1337
1338		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1339
1340		CFG_SPD_BUS_NUM
1341
1342		If defined, then this indicates the I2C bus number for DDR SPD.
1343		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1344
1345		CFG_RTC_BUS_NUM
1346
1347		If defined, then this indicates the I2C bus number for the RTC.
1348		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1349
1350		CFG_DTT_BUS_NUM
1351
1352		If defined, then this indicates the I2C bus number for the DTT.
1353		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1354
1355		CONFIG_FSL_I2C
1356
1357		Define this option if you want to use Freescale's I2C driver in
1358		drivers/i2c/fsl_i2c.c.
1359
1360
1361- SPI Support:	CONFIG_SPI
1362
1363		Enables SPI driver (so far only tested with
1364		SPI EEPROM, also an instance works with Crystal A/D and
1365		D/As on the SACSng board)
1366
1367		CONFIG_SPI_X
1368
1369		Enables extended (16-bit) SPI EEPROM addressing.
1370		(symmetrical to CONFIG_I2C_X)
1371
1372		CONFIG_SOFT_SPI
1373
1374		Enables a software (bit-bang) SPI driver rather than
1375		using hardware support. This is a general purpose
1376		driver that only requires three general I/O port pins
1377		(two outputs, one input) to function. If this is
1378		defined, the board configuration must define several
1379		SPI configuration items (port pins to use, etc). For
1380		an example, see include/configs/sacsng.h.
1381
1382		CONFIG_HARD_SPI
1383
1384		Enables a hardware SPI driver for general-purpose reads
1385		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1386		must define a list of chip-select function pointers.
1387		Currently supported on some MPC8xxx processors.  For an
1388		example, see include/configs/mpc8349emds.h.
1389
1390- FPGA Support: CONFIG_FPGA
1391
1392		Enables FPGA subsystem.
1393
1394		CONFIG_FPGA_<vendor>
1395
1396		Enables support for specific chip vendors.
1397		(ALTERA, XILINX)
1398
1399		CONFIG_FPGA_<family>
1400
1401		Enables support for FPGA family.
1402		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1403
1404		CONFIG_FPGA_COUNT
1405
1406		Specify the number of FPGA devices to support.
1407
1408		CFG_FPGA_PROG_FEEDBACK
1409
1410		Enable printing of hash marks during FPGA configuration.
1411
1412		CFG_FPGA_CHECK_BUSY
1413
1414		Enable checks on FPGA configuration interface busy
1415		status by the configuration function. This option
1416		will require a board or device specific function to
1417		be written.
1418
1419		CONFIG_FPGA_DELAY
1420
1421		If defined, a function that provides delays in the FPGA
1422		configuration driver.
1423
1424		CFG_FPGA_CHECK_CTRLC
1425		Allow Control-C to interrupt FPGA configuration
1426
1427		CFG_FPGA_CHECK_ERROR
1428
1429		Check for configuration errors during FPGA bitfile
1430		loading. For example, abort during Virtex II
1431		configuration if the INIT_B line goes low (which
1432		indicated a CRC error).
1433
1434		CFG_FPGA_WAIT_INIT
1435
1436		Maximum time to wait for the INIT_B line to deassert
1437		after PROB_B has been deasserted during a Virtex II
1438		FPGA configuration sequence. The default time is 500
1439		mS.
1440
1441		CFG_FPGA_WAIT_BUSY
1442
1443		Maximum time to wait for BUSY to deassert during
1444		Virtex II FPGA configuration. The default is 5 mS.
1445
1446		CFG_FPGA_WAIT_CONFIG
1447
1448		Time to wait after FPGA configuration. The default is
1449		200 mS.
1450
1451- Configuration Management:
1452		CONFIG_IDENT_STRING
1453
1454		If defined, this string will be added to the U-Boot
1455		version information (U_BOOT_VERSION)
1456
1457- Vendor Parameter Protection:
1458
1459		U-Boot considers the values of the environment
1460		variables "serial#" (Board Serial Number) and
1461		"ethaddr" (Ethernet Address) to be parameters that
1462		are set once by the board vendor / manufacturer, and
1463		protects these variables from casual modification by
1464		the user. Once set, these variables are read-only,
1465		and write or delete attempts are rejected. You can
1466		change this behviour:
1467
1468		If CONFIG_ENV_OVERWRITE is #defined in your config
1469		file, the write protection for vendor parameters is
1470		completely disabled. Anybody can change or delete
1471		these parameters.
1472
1473		Alternatively, if you #define _both_ CONFIG_ETHADDR
1474		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1475		ethernet address is installed in the environment,
1476		which can be changed exactly ONCE by the user. [The
1477		serial# is unaffected by this, i. e. it remains
1478		read-only.]
1479
1480- Protected RAM:
1481		CONFIG_PRAM
1482
1483		Define this variable to enable the reservation of
1484		"protected RAM", i. e. RAM which is not overwritten
1485		by U-Boot. Define CONFIG_PRAM to hold the number of
1486		kB you want to reserve for pRAM. You can overwrite
1487		this default value by defining an environment
1488		variable "pram" to the number of kB you want to
1489		reserve. Note that the board info structure will
1490		still show the full amount of RAM. If pRAM is
1491		reserved, a new environment variable "mem" will
1492		automatically be defined to hold the amount of
1493		remaining RAM in a form that can be passed as boot
1494		argument to Linux, for instance like that:
1495
1496			setenv bootargs ... mem=\${mem}
1497			saveenv
1498
1499		This way you can tell Linux not to use this memory,
1500		either, which results in a memory region that will
1501		not be affected by reboots.
1502
1503		*WARNING* If your board configuration uses automatic
1504		detection of the RAM size, you must make sure that
1505		this memory test is non-destructive. So far, the
1506		following board configurations are known to be
1507		"pRAM-clean":
1508
1509			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1510			HERMES, IP860, RPXlite, LWMON, LANTEC,
1511			PCU_E, FLAGADM, TQM8260
1512
1513- Error Recovery:
1514		CONFIG_PANIC_HANG
1515
1516		Define this variable to stop the system in case of a
1517		fatal error, so that you have to reset it manually.
1518		This is probably NOT a good idea for an embedded
1519		system where you want to system to reboot
1520		automatically as fast as possible, but it may be
1521		useful during development since you can try to debug
1522		the conditions that lead to the situation.
1523
1524		CONFIG_NET_RETRY_COUNT
1525
1526		This variable defines the number of retries for
1527		network operations like ARP, RARP, TFTP, or BOOTP
1528		before giving up the operation. If not defined, a
1529		default value of 5 is used.
1530
1531- Command Interpreter:
1532		CONFIG_AUTO_COMPLETE
1533
1534		Enable auto completion of commands using TAB.
1535
1536		Note that this feature has NOT been implemented yet
1537		for the "hush" shell.
1538
1539
1540		CFG_HUSH_PARSER
1541
1542		Define this variable to enable the "hush" shell (from
1543		Busybox) as command line interpreter, thus enabling
1544		powerful command line syntax like
1545		if...then...else...fi conditionals or `&&' and '||'
1546		constructs ("shell scripts").
1547
1548		If undefined, you get the old, much simpler behaviour
1549		with a somewhat smaller memory footprint.
1550
1551
1552		CFG_PROMPT_HUSH_PS2
1553
1554		This defines the secondary prompt string, which is
1555		printed when the command interpreter needs more input
1556		to complete a command. Usually "> ".
1557
1558	Note:
1559
1560		In the current implementation, the local variables
1561		space and global environment variables space are
1562		separated. Local variables are those you define by
1563		simply typing `name=value'. To access a local
1564		variable later on, you have write `$name' or
1565		`${name}'; to execute the contents of a variable
1566		directly type `$name' at the command prompt.
1567
1568		Global environment variables are those you use
1569		setenv/printenv to work with. To run a command stored
1570		in such a variable, you need to use the run command,
1571		and you must not use the '$' sign to access them.
1572
1573		To store commands and special characters in a
1574		variable, please use double quotation marks
1575		surrounding the whole text of the variable, instead
1576		of the backslashes before semicolons and special
1577		symbols.
1578
1579- Commandline Editing and History:
1580		CONFIG_CMDLINE_EDITING
1581
1582		Enable editiong and History functions for interactive
1583		commandline input operations
1584
1585- Default Environment:
1586		CONFIG_EXTRA_ENV_SETTINGS
1587
1588		Define this to contain any number of null terminated
1589		strings (variable = value pairs) that will be part of
1590		the default environment compiled into the boot image.
1591
1592		For example, place something like this in your
1593		board's config file:
1594
1595		#define CONFIG_EXTRA_ENV_SETTINGS \
1596			"myvar1=value1\0" \
1597			"myvar2=value2\0"
1598
1599		Warning: This method is based on knowledge about the
1600		internal format how the environment is stored by the
1601		U-Boot code. This is NOT an official, exported
1602		interface! Although it is unlikely that this format
1603		will change soon, there is no guarantee either.
1604		You better know what you are doing here.
1605
1606		Note: overly (ab)use of the default environment is
1607		discouraged. Make sure to check other ways to preset
1608		the environment like the autoscript function or the
1609		boot command first.
1610
1611- DataFlash Support:
1612		CONFIG_HAS_DATAFLASH
1613
1614		Defining this option enables DataFlash features and
1615		allows to read/write in Dataflash via the standard
1616		commands cp, md...
1617
1618- SystemACE Support:
1619		CONFIG_SYSTEMACE
1620
1621		Adding this option adds support for Xilinx SystemACE
1622		chips attached via some sort of local bus. The address
1623		of the chip must alsh be defined in the
1624		CFG_SYSTEMACE_BASE macro. For example:
1625
1626		#define CONFIG_SYSTEMACE
1627		#define CFG_SYSTEMACE_BASE 0xf0000000
1628
1629		When SystemACE support is added, the "ace" device type
1630		becomes available to the fat commands, i.e. fatls.
1631
1632- TFTP Fixed UDP Port:
1633		CONFIG_TFTP_PORT
1634
1635		If this is defined, the environment variable tftpsrcp
1636		is used to supply the TFTP UDP source port value.
1637		If tftpsrcp isn't defined, the normal pseudo-random port
1638		number generator is used.
1639
1640		Also, the environment variable tftpdstp is used to supply
1641		the TFTP UDP destination port value.  If tftpdstp isn't
1642		defined, the normal port 69 is used.
1643
1644		The purpose for tftpsrcp is to allow a TFTP server to
1645		blindly start the TFTP transfer using the pre-configured
1646		target IP address and UDP port. This has the effect of
1647		"punching through" the (Windows XP) firewall, allowing
1648		the remainder of the TFTP transfer to proceed normally.
1649		A better solution is to properly configure the firewall,
1650		but sometimes that is not allowed.
1651
1652- Show boot progress:
1653		CONFIG_SHOW_BOOT_PROGRESS
1654
1655		Defining this option allows to add some board-
1656		specific code (calling a user-provided function
1657		"show_boot_progress(int)") that enables you to show
1658		the system's boot progress on some display (for
1659		example, some LED's) on your board. At the moment,
1660		the following checkpoints are implemented:
1661
1662Legacy uImage format:
1663
1664  Arg	Where			When
1665    1	common/cmd_bootm.c	before attempting to boot an image
1666   -1	common/cmd_bootm.c	Image header has bad	 magic number
1667    2	common/cmd_bootm.c	Image header has correct magic number
1668   -2	common/cmd_bootm.c	Image header has bad	 checksum
1669    3	common/cmd_bootm.c	Image header has correct checksum
1670   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1671    4	common/cmd_bootm.c	Image data   has correct checksum
1672   -4	common/cmd_bootm.c	Image is for unsupported architecture
1673    5	common/cmd_bootm.c	Architecture check OK
1674   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1675    6	common/cmd_bootm.c	Image Type check OK
1676   -6	common/cmd_bootm.c	gunzip uncompression error
1677   -7	common/cmd_bootm.c	Unimplemented compression type
1678    7	common/cmd_bootm.c	Uncompression OK
1679    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1680   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1681
1682    9	common/image.c		Start initial ramdisk verification
1683  -10	common/image.c		Ramdisk header has bad	   magic number
1684  -11	common/image.c		Ramdisk header has bad	   checksum
1685   10	common/image.c		Ramdisk header is OK
1686  -12	common/image.c		Ramdisk data   has bad	   checksum
1687   11	common/image.c		Ramdisk data   has correct checksum
1688   12	common/image.c		Ramdisk verification complete, start loading
1689  -13	common/image.c		Wrong Image Type (not PPC Linux Ramdisk)
1690   13	common/image.c		Start multifile image verification
1691   14	common/image.c		No initial ramdisk, no multifile, continue.
1692
1693   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1694
1695  -30	lib_ppc/board.c		Fatal error, hang the system
1696  -31	post/post.c		POST test failed, detected by post_output_backlog()
1697  -32	post/post.c		POST test failed, detected by post_run_single()
1698
1699   34	common/cmd_doc.c	before loading a Image from a DOC device
1700  -35	common/cmd_doc.c	Bad usage of "doc" command
1701   35	common/cmd_doc.c	correct usage of "doc" command
1702  -36	common/cmd_doc.c	No boot device
1703   36	common/cmd_doc.c	correct boot device
1704  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1705   37	common/cmd_doc.c	correct chip ID found, device available
1706  -38	common/cmd_doc.c	Read Error on boot device
1707   38	common/cmd_doc.c	reading Image header from DOC device OK
1708  -39	common/cmd_doc.c	Image header has bad magic number
1709   39	common/cmd_doc.c	Image header has correct magic number
1710  -40	common/cmd_doc.c	Error reading Image from DOC device
1711   40	common/cmd_doc.c	Image header has correct magic number
1712   41	common/cmd_ide.c	before loading a Image from a IDE device
1713  -42	common/cmd_ide.c	Bad usage of "ide" command
1714   42	common/cmd_ide.c	correct usage of "ide" command
1715  -43	common/cmd_ide.c	No boot device
1716   43	common/cmd_ide.c	boot device found
1717  -44	common/cmd_ide.c	Device not available
1718   44	common/cmd_ide.c	Device available
1719  -45	common/cmd_ide.c	wrong partition selected
1720   45	common/cmd_ide.c	partition selected
1721  -46	common/cmd_ide.c	Unknown partition table
1722   46	common/cmd_ide.c	valid partition table found
1723  -47	common/cmd_ide.c	Invalid partition type
1724   47	common/cmd_ide.c	correct partition type
1725  -48	common/cmd_ide.c	Error reading Image Header on boot device
1726   48	common/cmd_ide.c	reading Image Header from IDE device OK
1727  -49	common/cmd_ide.c	Image header has bad magic number
1728   49	common/cmd_ide.c	Image header has correct magic number
1729  -50	common/cmd_ide.c	Image header has bad	 checksum
1730   50	common/cmd_ide.c	Image header has correct checksum
1731  -51	common/cmd_ide.c	Error reading Image from IDE device
1732   51	common/cmd_ide.c	reading Image from IDE device OK
1733   52	common/cmd_nand.c	before loading a Image from a NAND device
1734  -53	common/cmd_nand.c	Bad usage of "nand" command
1735   53	common/cmd_nand.c	correct usage of "nand" command
1736  -54	common/cmd_nand.c	No boot device
1737   54	common/cmd_nand.c	boot device found
1738  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1739   55	common/cmd_nand.c	correct chip ID found, device available
1740  -56	common/cmd_nand.c	Error reading Image Header on boot device
1741   56	common/cmd_nand.c	reading Image Header from NAND device OK
1742  -57	common/cmd_nand.c	Image header has bad magic number
1743   57	common/cmd_nand.c	Image header has correct magic number
1744  -58	common/cmd_nand.c	Error reading Image from NAND device
1745   58	common/cmd_nand.c	reading Image from NAND device OK
1746
1747  -60	common/env_common.c	Environment has a bad CRC, using default
1748
1749   64	net/eth.c		starting with Ethernetconfiguration.
1750  -64	net/eth.c		no Ethernet found.
1751   65	net/eth.c		Ethernet found.
1752
1753  -80	common/cmd_net.c	usage wrong
1754   80	common/cmd_net.c	before calling NetLoop()
1755  -81	common/cmd_net.c	some error in NetLoop() occured
1756   81	common/cmd_net.c	NetLoop() back without error
1757  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1758   82	common/cmd_net.c	trying automatic boot
1759   83	common/cmd_net.c	running autoscript
1760  -83	common/cmd_net.c	some error in automatic boot or autoscript
1761   84	common/cmd_net.c	end without errors
1762
1763FIT uImage format:
1764
1765  Arg	Where			When
1766  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1767 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1768  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1769 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
1770  102	common/cmd_bootm.c	Kernel unit name specified
1771 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
1772  103	common/cmd_bootm.c	Found configuration node
1773  104	common/cmd_bootm.c	Got kernel subimage node offset
1774 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
1775  105	common/cmd_bootm.c	Kernel subimage hash verification OK
1776 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
1777  106	common/cmd_bootm.c	Architecture check OK
1778 -106	common/cmd_bootm.c	Kernel subimage has wrong typea
1779  107	common/cmd_bootm.c	Kernel subimge type OK
1780 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
1781  108	common/cmd_bootm.c	Got kernel subimage data/size
1782 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
1783 -109	common/cmd_bootm.c	Can't get kernel subimage type
1784 -110	common/cmd_bootm.c	Can't get kernel subimage comp
1785 -111	common/cmd_bootm.c	Can't get kernel subimage os
1786 -112	common/cmd_bootm.c	Can't get kernel subimage load address
1787 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
1788
1789  120	common/image.c		Start initial ramdisk verification
1790 -120	common/image.c		Ramdisk FIT image has incorrect format
1791  121	common/image.c		Ramdisk FIT image has correct format
1792  122	common/image.c		No Ramdisk subimage unit name, using configuration
1793 -122	common/image.c		Can't get configuration for ramdisk subimage
1794  123	common/image.c		Ramdisk unit name specified
1795 -124	common/image.c		Can't get ramdisk subimage node offset
1796  125	common/image.c		Got ramdisk subimage node offset
1797 -125	common/image.c		Ramdisk subimage hash verification failed
1798  126	common/image.c		Ramdisk subimage hash verification OK
1799 -126	common/image.c		Ramdisk subimage for unsupported architecture
1800  127	common/image.c		Architecture check OK
1801 -127	common/image.c		Can't get ramdisk subimage data/size
1802  128	common/image.c		Got ramdisk subimage data/size
1803  129	common/image.c		Can't get ramdisk load address
1804 -129	common/image.c		Got ramdisk load address
1805
1806 -130	common/cmd_doc.c	Icorrect FIT image format
1807  131	common/cmd_doc.c	FIT image format OK
1808
1809 -140	common/cmd_ide.c	Icorrect FIT image format
1810  141	common/cmd_ide.c	FIT image format OK
1811
1812 -150	common/cmd_nand.c	Icorrect FIT image format
1813  151	common/cmd_nand.c	FIT image format OK
1814
1815
1816Modem Support:
1817--------------
1818
1819[so far only for SMDK2400 and TRAB boards]
1820
1821- Modem support endable:
1822		CONFIG_MODEM_SUPPORT
1823
1824- RTS/CTS Flow control enable:
1825		CONFIG_HWFLOW
1826
1827- Modem debug support:
1828		CONFIG_MODEM_SUPPORT_DEBUG
1829
1830		Enables debugging stuff (char screen[1024], dbg())
1831		for modem support. Useful only with BDI2000.
1832
1833- Interrupt support (PPC):
1834
1835		There are common interrupt_init() and timer_interrupt()
1836		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1837		for cpu specific initialization. interrupt_init_cpu()
1838		should set decrementer_count to appropriate value. If
1839		cpu resets decrementer automatically after interrupt
1840		(ppc4xx) it should set decrementer_count to zero.
1841		timer_interrupt() calls timer_interrupt_cpu() for cpu
1842		specific handling. If board has watchdog / status_led
1843		/ other_activity_monitor it works automatically from
1844		general timer_interrupt().
1845
1846- General:
1847
1848		In the target system modem support is enabled when a
1849		specific key (key combination) is pressed during
1850		power-on. Otherwise U-Boot will boot normally
1851		(autoboot). The key_pressed() fuction is called from
1852		board_init(). Currently key_pressed() is a dummy
1853		function, returning 1 and thus enabling modem
1854		initialization.
1855
1856		If there are no modem init strings in the
1857		environment, U-Boot proceed to autoboot; the
1858		previous output (banner, info printfs) will be
1859		supressed, though.
1860
1861		See also: doc/README.Modem
1862
1863
1864Configuration Settings:
1865-----------------------
1866
1867- CFG_LONGHELP: Defined when you want long help messages included;
1868		undefine this when you're short of memory.
1869
1870- CFG_PROMPT:	This is what U-Boot prints on the console to
1871		prompt for user input.
1872
1873- CFG_CBSIZE:	Buffer size for input from the Console
1874
1875- CFG_PBSIZE:	Buffer size for Console output
1876
1877- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1878
1879- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1880		the application (usually a Linux kernel) when it is
1881		booted
1882
1883- CFG_BAUDRATE_TABLE:
1884		List of legal baudrate settings for this board.
1885
1886- CFG_CONSOLE_INFO_QUIET
1887		Suppress display of console information at boot.
1888
1889- CFG_CONSOLE_IS_IN_ENV
1890		If the board specific function
1891			extern int overwrite_console (void);
1892		returns 1, the stdin, stderr and stdout are switched to the
1893		serial port, else the settings in the environment are used.
1894
1895- CFG_CONSOLE_OVERWRITE_ROUTINE
1896		Enable the call to overwrite_console().
1897
1898- CFG_CONSOLE_ENV_OVERWRITE
1899		Enable overwrite of previous console environment settings.
1900
1901- CFG_MEMTEST_START, CFG_MEMTEST_END:
1902		Begin and End addresses of the area used by the
1903		simple memory test.
1904
1905- CFG_ALT_MEMTEST:
1906		Enable an alternate, more extensive memory test.
1907
1908- CFG_MEMTEST_SCRATCH:
1909		Scratch address used by the alternate memory test
1910		You only need to set this if address zero isn't writeable
1911
1912- CFG_TFTP_LOADADDR:
1913		Default load address for network file downloads
1914
1915- CFG_LOADS_BAUD_CHANGE:
1916		Enable temporary baudrate change while serial download
1917
1918- CFG_SDRAM_BASE:
1919		Physical start address of SDRAM. _Must_ be 0 here.
1920
1921- CFG_MBIO_BASE:
1922		Physical start address of Motherboard I/O (if using a
1923		Cogent motherboard)
1924
1925- CFG_FLASH_BASE:
1926		Physical start address of Flash memory.
1927
1928- CFG_MONITOR_BASE:
1929		Physical start address of boot monitor code (set by
1930		make config files to be same as the text base address
1931		(TEXT_BASE) used when linking) - same as
1932		CFG_FLASH_BASE when booting from flash.
1933
1934- CFG_MONITOR_LEN:
1935		Size of memory reserved for monitor code, used to
1936		determine _at_compile_time_ (!) if the environment is
1937		embedded within the U-Boot image, or in a separate
1938		flash sector.
1939
1940- CFG_MALLOC_LEN:
1941		Size of DRAM reserved for malloc() use.
1942
1943- CFG_BOOTM_LEN:
1944		Normally compressed uImages are limited to an
1945		uncompressed size of 8 MBytes. If this is not enough,
1946		you can define CFG_BOOTM_LEN in your board config file
1947		to adjust this setting to your needs.
1948
1949- CFG_BOOTMAPSZ:
1950		Maximum size of memory mapped by the startup code of
1951		the Linux kernel; all data that must be processed by
1952		the Linux kernel (bd_info, boot arguments, eventually
1953		initrd image) must be put below this limit.
1954
1955- CFG_MAX_FLASH_BANKS:
1956		Max number of Flash memory banks
1957
1958- CFG_MAX_FLASH_SECT:
1959		Max number of sectors on a Flash chip
1960
1961- CFG_FLASH_ERASE_TOUT:
1962		Timeout for Flash erase operations (in ms)
1963
1964- CFG_FLASH_WRITE_TOUT:
1965		Timeout for Flash write operations (in ms)
1966
1967- CFG_FLASH_LOCK_TOUT
1968		Timeout for Flash set sector lock bit operation (in ms)
1969
1970- CFG_FLASH_UNLOCK_TOUT
1971		Timeout for Flash clear lock bits operation (in ms)
1972
1973- CFG_FLASH_PROTECTION
1974		If defined, hardware flash sectors protection is used
1975		instead of U-Boot software protection.
1976
1977- CFG_DIRECT_FLASH_TFTP:
1978
1979		Enable TFTP transfers directly to flash memory;
1980		without this option such a download has to be
1981		performed in two steps: (1) download to RAM, and (2)
1982		copy from RAM to flash.
1983
1984		The two-step approach is usually more reliable, since
1985		you can check if the download worked before you erase
1986		the flash, but in some situations (when sytem RAM is
1987		too limited to allow for a tempory copy of the
1988		downloaded image) this option may be very useful.
1989
1990- CFG_FLASH_CFI:
1991		Define if the flash driver uses extra elements in the
1992		common flash structure for storing flash geometry.
1993
1994- CFG_FLASH_CFI_DRIVER
1995		This option also enables the building of the cfi_flash driver
1996		in the drivers directory
1997
1998- CFG_FLASH_QUIET_TEST
1999		If this option is defined, the common CFI flash doesn't
2000		print it's warning upon not recognized FLASH banks. This
2001		is useful, if some of the configured banks are only
2002		optionally available.
2003
2004- CFG_RX_ETH_BUFFER:
2005		Defines the number of ethernet receive buffers. On some
2006		ethernet controllers it is recommended to set this value
2007		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2008		buffers can be full shortly after enabling the interface
2009		on high ethernet traffic.
2010		Defaults to 4 if not defined.
2011
2012The following definitions that deal with the placement and management
2013of environment data (variable area); in general, we support the
2014following configurations:
2015
2016- CFG_ENV_IS_IN_FLASH:
2017
2018	Define this if the environment is in flash memory.
2019
2020	a) The environment occupies one whole flash sector, which is
2021	   "embedded" in the text segment with the U-Boot code. This
2022	   happens usually with "bottom boot sector" or "top boot
2023	   sector" type flash chips, which have several smaller
2024	   sectors at the start or the end. For instance, such a
2025	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2026	   such a case you would place the environment in one of the
2027	   4 kB sectors - with U-Boot code before and after it. With
2028	   "top boot sector" type flash chips, you would put the
2029	   environment in one of the last sectors, leaving a gap
2030	   between U-Boot and the environment.
2031
2032	- CFG_ENV_OFFSET:
2033
2034	   Offset of environment data (variable area) to the
2035	   beginning of flash memory; for instance, with bottom boot
2036	   type flash chips the second sector can be used: the offset
2037	   for this sector is given here.
2038
2039	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
2040
2041	- CFG_ENV_ADDR:
2042
2043	   This is just another way to specify the start address of
2044	   the flash sector containing the environment (instead of
2045	   CFG_ENV_OFFSET).
2046
2047	- CFG_ENV_SECT_SIZE:
2048
2049	   Size of the sector containing the environment.
2050
2051
2052	b) Sometimes flash chips have few, equal sized, BIG sectors.
2053	   In such a case you don't want to spend a whole sector for
2054	   the environment.
2055
2056	- CFG_ENV_SIZE:
2057
2058	   If you use this in combination with CFG_ENV_IS_IN_FLASH
2059	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
2060	   of this flash sector for the environment. This saves
2061	   memory for the RAM copy of the environment.
2062
2063	   It may also save flash memory if you decide to use this
2064	   when your environment is "embedded" within U-Boot code,
2065	   since then the remainder of the flash sector could be used
2066	   for U-Boot code. It should be pointed out that this is
2067	   STRONGLY DISCOURAGED from a robustness point of view:
2068	   updating the environment in flash makes it always
2069	   necessary to erase the WHOLE sector. If something goes
2070	   wrong before the contents has been restored from a copy in
2071	   RAM, your target system will be dead.
2072
2073	- CFG_ENV_ADDR_REDUND
2074	  CFG_ENV_SIZE_REDUND
2075
2076	   These settings describe a second storage area used to hold
2077	   a redundand copy of the environment data, so that there is
2078	   a valid backup copy in case there is a power failure during
2079	   a "saveenv" operation.
2080
2081BE CAREFUL! Any changes to the flash layout, and some changes to the
2082source code will make it necessary to adapt <board>/u-boot.lds*
2083accordingly!
2084
2085
2086- CFG_ENV_IS_IN_NVRAM:
2087
2088	Define this if you have some non-volatile memory device
2089	(NVRAM, battery buffered SRAM) which you want to use for the
2090	environment.
2091
2092	- CFG_ENV_ADDR:
2093	- CFG_ENV_SIZE:
2094
2095	  These two #defines are used to determin the memory area you
2096	  want to use for environment. It is assumed that this memory
2097	  can just be read and written to, without any special
2098	  provision.
2099
2100BE CAREFUL! The first access to the environment happens quite early
2101in U-Boot initalization (when we try to get the setting of for the
2102console baudrate). You *MUST* have mappend your NVRAM area then, or
2103U-Boot will hang.
2104
2105Please note that even with NVRAM we still use a copy of the
2106environment in RAM: we could work on NVRAM directly, but we want to
2107keep settings there always unmodified except somebody uses "saveenv"
2108to save the current settings.
2109
2110
2111- CFG_ENV_IS_IN_EEPROM:
2112
2113	Use this if you have an EEPROM or similar serial access
2114	device and a driver for it.
2115
2116	- CFG_ENV_OFFSET:
2117	- CFG_ENV_SIZE:
2118
2119	  These two #defines specify the offset and size of the
2120	  environment area within the total memory of your EEPROM.
2121
2122	- CFG_I2C_EEPROM_ADDR:
2123	  If defined, specified the chip address of the EEPROM device.
2124	  The default address is zero.
2125
2126	- CFG_EEPROM_PAGE_WRITE_BITS:
2127	  If defined, the number of bits used to address bytes in a
2128	  single page in the EEPROM device.  A 64 byte page, for example
2129	  would require six bits.
2130
2131	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2132	  If defined, the number of milliseconds to delay between
2133	  page writes.	The default is zero milliseconds.
2134
2135	- CFG_I2C_EEPROM_ADDR_LEN:
2136	  The length in bytes of the EEPROM memory array address.  Note
2137	  that this is NOT the chip address length!
2138
2139	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2140	  EEPROM chips that implement "address overflow" are ones
2141	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2142	  address and the extra bits end up in the "chip address" bit
2143	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2144	  byte chips.
2145
2146	  Note that we consider the length of the address field to
2147	  still be one byte because the extra address bits are hidden
2148	  in the chip address.
2149
2150	- CFG_EEPROM_SIZE:
2151	  The size in bytes of the EEPROM device.
2152
2153
2154- CFG_ENV_IS_IN_DATAFLASH:
2155
2156	Define this if you have a DataFlash memory device which you
2157	want to use for the environment.
2158
2159	- CFG_ENV_OFFSET:
2160	- CFG_ENV_ADDR:
2161	- CFG_ENV_SIZE:
2162
2163	  These three #defines specify the offset and size of the
2164	  environment area within the total memory of your DataFlash placed
2165	  at the specified address.
2166
2167- CFG_ENV_IS_IN_NAND:
2168
2169	Define this if you have a NAND device which you want to use
2170	for the environment.
2171
2172	- CFG_ENV_OFFSET:
2173	- CFG_ENV_SIZE:
2174
2175	  These two #defines specify the offset and size of the environment
2176	  area within the first NAND device.
2177
2178	- CFG_ENV_OFFSET_REDUND
2179
2180	  This setting describes a second storage area of CFG_ENV_SIZE
2181	  size used to hold a redundant copy of the environment data,
2182	  so that there is a valid backup copy in case there is a
2183	  power failure during a "saveenv" operation.
2184
2185	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2186	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2187	the NAND devices block size.
2188
2189- CFG_SPI_INIT_OFFSET
2190
2191	Defines offset to the initial SPI buffer area in DPRAM. The
2192	area is used at an early stage (ROM part) if the environment
2193	is configured to reside in the SPI EEPROM: We need a 520 byte
2194	scratch DPRAM area. It is used between the two initialization
2195	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2196	to be a good choice since it makes it far enough from the
2197	start of the data area as well as from the stack pointer.
2198
2199Please note that the environment is read-only until the monitor
2200has been relocated to RAM and a RAM copy of the environment has been
2201created; also, when using EEPROM you will have to use getenv_r()
2202until then to read environment variables.
2203
2204The environment is protected by a CRC32 checksum. Before the monitor
2205is relocated into RAM, as a result of a bad CRC you will be working
2206with the compiled-in default environment - *silently*!!! [This is
2207necessary, because the first environment variable we need is the
2208"baudrate" setting for the console - if we have a bad CRC, we don't
2209have any device yet where we could complain.]
2210
2211Note: once the monitor has been relocated, then it will complain if
2212the default environment is used; a new CRC is computed as soon as you
2213use the "saveenv" command to store a valid environment.
2214
2215- CFG_FAULT_ECHO_LINK_DOWN:
2216		Echo the inverted Ethernet link state to the fault LED.
2217
2218		Note: If this option is active, then CFG_FAULT_MII_ADDR
2219		      also needs to be defined.
2220
2221- CFG_FAULT_MII_ADDR:
2222		MII address of the PHY to check for the Ethernet link state.
2223
2224- CFG_64BIT_VSPRINTF:
2225		Makes vsprintf (and all *printf functions) support printing
2226		of 64bit values by using the L quantifier
2227
2228- CFG_64BIT_STRTOUL:
2229		Adds simple_strtoull that returns a 64bit value
2230
2231Low Level (hardware related) configuration options:
2232---------------------------------------------------
2233
2234- CFG_CACHELINE_SIZE:
2235		Cache Line Size of the CPU.
2236
2237- CFG_DEFAULT_IMMR:
2238		Default address of the IMMR after system reset.
2239
2240		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2241		and RPXsuper) to be able to adjust the position of
2242		the IMMR register after a reset.
2243
2244- Floppy Disk Support:
2245		CFG_FDC_DRIVE_NUMBER
2246
2247		the default drive number (default value 0)
2248
2249		CFG_ISA_IO_STRIDE
2250
2251		defines the spacing between fdc chipset registers
2252		(default value 1)
2253
2254		CFG_ISA_IO_OFFSET
2255
2256		defines the offset of register from address. It
2257		depends on which part of the data bus is connected to
2258		the fdc chipset. (default value 0)
2259
2260		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2261		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2262		default value.
2263
2264		if CFG_FDC_HW_INIT is defined, then the function
2265		fdc_hw_init() is called at the beginning of the FDC
2266		setup. fdc_hw_init() must be provided by the board
2267		source code. It is used to make hardware dependant
2268		initializations.
2269
2270- CFG_IMMR:	Physical address of the Internal Memory.
2271		DO NOT CHANGE unless you know exactly what you're
2272		doing! (11-4) [MPC8xx/82xx systems only]
2273
2274- CFG_INIT_RAM_ADDR:
2275
2276		Start address of memory area that can be used for
2277		initial data and stack; please note that this must be
2278		writable memory that is working WITHOUT special
2279		initialization, i. e. you CANNOT use normal RAM which
2280		will become available only after programming the
2281		memory controller and running certain initialization
2282		sequences.
2283
2284		U-Boot uses the following memory types:
2285		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2286		- MPC824X: data cache
2287		- PPC4xx:  data cache
2288
2289- CFG_GBL_DATA_OFFSET:
2290
2291		Offset of the initial data structure in the memory
2292		area defined by CFG_INIT_RAM_ADDR. Usually
2293		CFG_GBL_DATA_OFFSET is chosen such that the initial
2294		data is located at the end of the available space
2295		(sometimes written as (CFG_INIT_RAM_END -
2296		CFG_INIT_DATA_SIZE), and the initial stack is just
2297		below that area (growing from (CFG_INIT_RAM_ADDR +
2298		CFG_GBL_DATA_OFFSET) downward.
2299
2300	Note:
2301		On the MPC824X (or other systems that use the data
2302		cache for initial memory) the address chosen for
2303		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2304		point to an otherwise UNUSED address space between
2305		the top of RAM and the start of the PCI space.
2306
2307- CFG_SIUMCR:	SIU Module Configuration (11-6)
2308
2309- CFG_SYPCR:	System Protection Control (11-9)
2310
2311- CFG_TBSCR:	Time Base Status and Control (11-26)
2312
2313- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2314
2315- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2316
2317- CFG_SCCR:	System Clock and reset Control Register (15-27)
2318
2319- CFG_OR_TIMING_SDRAM:
2320		SDRAM timing
2321
2322- CFG_MAMR_PTA:
2323		periodic timer for refresh
2324
2325- CFG_DER:	Debug Event Register (37-47)
2326
2327- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2328  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2329  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2330  CFG_BR1_PRELIM:
2331		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2332
2333- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2334  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2335  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2336		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2337
2338- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2339  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2340		Machine Mode Register and Memory Periodic Timer
2341		Prescaler definitions (SDRAM timing)
2342
2343- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2344		enable I2C microcode relocation patch (MPC8xx);
2345		define relocation offset in DPRAM [DSP2]
2346
2347- CFG_SMC_UCODE_PATCH, CFG_SMC_DPMEM_OFFSET [0x1FC0]:
2348		enable SMC microcode relocation patch (MPC8xx);
2349		define relocation offset in DPRAM [SMC1]
2350
2351- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2352		enable SPI microcode relocation patch (MPC8xx);
2353		define relocation offset in DPRAM [SCC4]
2354
2355- CFG_USE_OSCCLK:
2356		Use OSCM clock mode on MBX8xx board. Be careful,
2357		wrong setting might damage your board. Read
2358		doc/README.MBX before setting this variable!
2359
2360- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2361		Offset of the bootmode word in DPRAM used by post
2362		(Power On Self Tests). This definition overrides
2363		#define'd default value in commproc.h resp.
2364		cpm_8260.h.
2365
2366- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2367  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2368  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2369  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2370  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2371  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2372  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2373  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2374		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2375
2376- CONFIG_SPD_EEPROM
2377		Get DDR timing information from an I2C EEPROM.  Common with pluggable
2378		memory modules such as SODIMMs
2379  SPD_EEPROM_ADDRESS
2380		I2C address of the SPD EEPROM
2381
2382- CFG_SPD_BUS_NUM
2383		If SPD EEPROM is on an I2C bus other than the first one, specify here.
2384		Note that the value must resolve to something your driver can deal with.
2385
2386- CFG_83XX_DDR_USES_CS0
2387		Only for 83xx systems. If specified, then DDR should be configured
2388		using CS0 and CS1 instead of CS2 and CS3.
2389
2390- CFG_83XX_DDR_USES_CS0
2391		Only for 83xx systems. If specified, then DDR should be configured
2392		using CS0 and CS1 instead of CS2 and CS3.
2393
2394- CONFIG_ETHER_ON_FEC[12]
2395		Define to enable FEC[12] on a 8xx series processor.
2396
2397- CONFIG_FEC[12]_PHY
2398		Define to the hardcoded PHY address which corresponds
2399		to the given FEC; i. e.
2400			#define CONFIG_FEC1_PHY 4
2401		means that the PHY with address 4 is connected to FEC1
2402
2403		When set to -1, means to probe for first available.
2404
2405- CONFIG_FEC[12]_PHY_NORXERR
2406		The PHY does not have a RXERR line (RMII only).
2407		(so program the FEC to ignore it).
2408
2409- CONFIG_RMII
2410		Enable RMII mode for all FECs.
2411		Note that this is a global option, we can't
2412		have one FEC in standard MII mode and another in RMII mode.
2413
2414- CONFIG_CRC32_VERIFY
2415		Add a verify option to the crc32 command.
2416		The syntax is:
2417
2418		=> crc32 -v <address> <count> <crc32>
2419
2420		Where address/count indicate a memory area
2421		and crc32 is the correct crc32 which the
2422		area should have.
2423
2424- CONFIG_LOOPW
2425		Add the "loopw" memory command. This only takes effect if
2426		the memory commands are activated globally (CONFIG_CMD_MEM).
2427
2428- CONFIG_MX_CYCLIC
2429		Add the "mdc" and "mwc" memory commands. These are cyclic
2430		"md/mw" commands.
2431		Examples:
2432
2433		=> mdc.b 10 4 500
2434		This command will print 4 bytes (10,11,12,13) each 500 ms.
2435
2436		=> mwc.l 100 12345678 10
2437		This command will write 12345678 to address 100 all 10 ms.
2438
2439		This only takes effect if the memory commands are activated
2440		globally (CONFIG_CMD_MEM).
2441
2442- CONFIG_SKIP_LOWLEVEL_INIT
2443- CONFIG_SKIP_RELOCATE_UBOOT
2444
2445		[ARM only] If these variables are defined, then
2446		certain low level initializations (like setting up
2447		the memory controller) are omitted and/or U-Boot does
2448		not relocate itself into RAM.
2449		Normally these variables MUST NOT be defined. The
2450		only exception is when U-Boot is loaded (to RAM) by
2451		some other boot loader or by a debugger which
2452		performs these intializations itself.
2453
2454
2455Building the Software:
2456======================
2457
2458Building U-Boot has been tested in native PPC environments (on a
2459PowerBook G3 running LinuxPPC 2000) and in cross environments
2460(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2461NetBSD 1.5 on x86).
2462
2463If you are not using a native PPC environment, it is assumed that you
2464have the GNU cross compiling tools available in your path and named
2465with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2466you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2467the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2468change it to:
2469
2470	CROSS_COMPILE = ppc_4xx-
2471
2472
2473U-Boot is intended to be  simple  to  build.  After  installing	 the
2474sources	 you must configure U-Boot for one specific board type. This
2475is done by typing:
2476
2477	make NAME_config
2478
2479where "NAME_config" is the name of one of the existing
2480configurations; see the main Makefile for supported names.
2481
2482Note: for some board special configuration names may exist; check if
2483      additional information is available from the board vendor; for
2484      instance, the TQM823L systems are available without (standard)
2485      or with LCD support. You can select such additional "features"
2486      when chosing the configuration, i. e.
2487
2488      make TQM823L_config
2489	- will configure for a plain TQM823L, i. e. no LCD support
2490
2491      make TQM823L_LCD_config
2492	- will configure for a TQM823L with U-Boot console on LCD
2493
2494      etc.
2495
2496
2497Finally, type "make all", and you should get some working U-Boot
2498images ready for download to / installation on your system:
2499
2500- "u-boot.bin" is a raw binary image
2501- "u-boot" is an image in ELF binary format
2502- "u-boot.srec" is in Motorola S-Record format
2503
2504By default the build is performed locally and the objects are saved
2505in the source directory. One of the two methods can be used to change
2506this behavior and build U-Boot to some external directory:
2507
25081. Add O= to the make command line invocations:
2509
2510	make O=/tmp/build distclean
2511	make O=/tmp/build NAME_config
2512	make O=/tmp/build all
2513
25142. Set environment variable BUILD_DIR to point to the desired location:
2515
2516	export BUILD_DIR=/tmp/build
2517	make distclean
2518	make NAME_config
2519	make all
2520
2521Note that the command line "O=" setting overrides the BUILD_DIR environment
2522variable.
2523
2524
2525Please be aware that the Makefiles assume you are using GNU make, so
2526for instance on NetBSD you might need to use "gmake" instead of
2527native "make".
2528
2529
2530If the system board that you have is not listed, then you will need
2531to port U-Boot to your hardware platform. To do this, follow these
2532steps:
2533
25341.  Add a new configuration option for your board to the toplevel
2535    "Makefile" and to the "MAKEALL" script, using the existing
2536    entries as examples. Note that here and at many other places
2537    boards and other names are listed in alphabetical sort order. Please
2538    keep this order.
25392.  Create a new directory to hold your board specific code. Add any
2540    files you need. In your board directory, you will need at least
2541    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
25423.  Create a new configuration file "include/configs/<board>.h" for
2543    your board
25443.  If you're porting U-Boot to a new CPU, then also create a new
2545    directory to hold your CPU specific code. Add any files you need.
25464.  Run "make <board>_config" with your new name.
25475.  Type "make", and you should get a working "u-boot.srec" file
2548    to be installed on your target system.
25496.  Debug and solve any problems that might arise.
2550    [Of course, this last step is much harder than it sounds.]
2551
2552
2553Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2554==============================================================
2555
2556If you have modified U-Boot sources (for instance added a new	board
2557or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2558provide feedback to the other developers. The feedback normally takes
2559the form of a "patch", i. e. a context diff against a certain (latest
2560official or latest in CVS) version of U-Boot sources.
2561
2562But before you submit such a patch, please verify that	your  modifi-
2563cation	did not break existing code. At least make sure that *ALL* of
2564the supported boards compile WITHOUT ANY compiler warnings. To do so,
2565just run the "MAKEALL" script, which will configure and build U-Boot
2566for ALL supported system. Be warned, this will take a while. You  can
2567select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2568environment variable to the script, i. e. to use the cross tools from
2569MontaVista's Hard Hat Linux you can type
2570
2571	CROSS_COMPILE=ppc_8xx- MAKEALL
2572
2573or to build on a native PowerPC system you can type
2574
2575	CROSS_COMPILE=' ' MAKEALL
2576
2577When using the MAKEALL script, the default behaviour is to build U-Boot
2578in the source directory. This location can be changed by setting the
2579BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2580script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2581<source dir>/LOG directory. This default location can be changed by
2582setting the MAKEALL_LOGDIR environment variable. For example:
2583
2584	export BUILD_DIR=/tmp/build
2585	export MAKEALL_LOGDIR=/tmp/log
2586	CROSS_COMPILE=ppc_8xx- MAKEALL
2587
2588With the above settings build objects are saved in the /tmp/build, log
2589files are saved in the /tmp/log and the source tree remains clean during
2590the whole build process.
2591
2592
2593See also "U-Boot Porting Guide" below.
2594
2595
2596Monitor Commands - Overview:
2597============================
2598
2599go	- start application at address 'addr'
2600run	- run commands in an environment variable
2601bootm	- boot application image from memory
2602bootp	- boot image via network using BootP/TFTP protocol
2603tftpboot- boot image via network using TFTP protocol
2604	       and env variables "ipaddr" and "serverip"
2605	       (and eventually "gatewayip")
2606rarpboot- boot image via network using RARP/TFTP protocol
2607diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2608loads	- load S-Record file over serial line
2609loadb	- load binary file over serial line (kermit mode)
2610md	- memory display
2611mm	- memory modify (auto-incrementing)
2612nm	- memory modify (constant address)
2613mw	- memory write (fill)
2614cp	- memory copy
2615cmp	- memory compare
2616crc32	- checksum calculation
2617imd	- i2c memory display
2618imm	- i2c memory modify (auto-incrementing)
2619inm	- i2c memory modify (constant address)
2620imw	- i2c memory write (fill)
2621icrc32	- i2c checksum calculation
2622iprobe	- probe to discover valid I2C chip addresses
2623iloop	- infinite loop on address range
2624isdram	- print SDRAM configuration information
2625sspi	- SPI utility commands
2626base	- print or set address offset
2627printenv- print environment variables
2628setenv	- set environment variables
2629saveenv - save environment variables to persistent storage
2630protect - enable or disable FLASH write protection
2631erase	- erase FLASH memory
2632flinfo	- print FLASH memory information
2633bdinfo	- print Board Info structure
2634iminfo	- print header information for application image
2635coninfo - print console devices and informations
2636ide	- IDE sub-system
2637loop	- infinite loop on address range
2638loopw	- infinite write loop on address range
2639mtest	- simple RAM test
2640icache	- enable or disable instruction cache
2641dcache	- enable or disable data cache
2642reset	- Perform RESET of the CPU
2643echo	- echo args to console
2644version - print monitor version
2645help	- print online help
2646?	- alias for 'help'
2647
2648
2649Monitor Commands - Detailed Description:
2650========================================
2651
2652TODO.
2653
2654For now: just type "help <command>".
2655
2656
2657Environment Variables:
2658======================
2659
2660U-Boot supports user configuration using Environment Variables which
2661can be made persistent by saving to Flash memory.
2662
2663Environment Variables are set using "setenv", printed using
2664"printenv", and saved to Flash using "saveenv". Using "setenv"
2665without a value can be used to delete a variable from the
2666environment. As long as you don't save the environment you are
2667working with an in-memory copy. In case the Flash area containing the
2668environment is erased by accident, a default environment is provided.
2669
2670Some configuration options can be set using Environment Variables:
2671
2672  baudrate	- see CONFIG_BAUDRATE
2673
2674  bootdelay	- see CONFIG_BOOTDELAY
2675
2676  bootcmd	- see CONFIG_BOOTCOMMAND
2677
2678  bootargs	- Boot arguments when booting an RTOS image
2679
2680  bootfile	- Name of the image to load with TFTP
2681
2682  autoload	- if set to "no" (any string beginning with 'n'),
2683		  "bootp" will just load perform a lookup of the
2684		  configuration from the BOOTP server, but not try to
2685		  load any image using TFTP
2686
2687  autostart	- if set to "yes", an image loaded using the "bootp",
2688		  "rarpboot", "tftpboot" or "diskboot" commands will
2689		  be automatically started (by internally calling
2690		  "bootm")
2691
2692		  If set to "no", a standalone image passed to the
2693		  "bootm" command will be copied to the load address
2694		  (and eventually uncompressed), but NOT be started.
2695		  This can be used to load and uncompress arbitrary
2696		  data.
2697
2698  i2cfast	- (PPC405GP|PPC405EP only)
2699		  if set to 'y' configures Linux I2C driver for fast
2700		  mode (400kHZ). This environment variable is used in
2701		  initialization code. So, for changes to be effective
2702		  it must be saved and board must be reset.
2703
2704  initrd_high	- restrict positioning of initrd images:
2705		  If this variable is not set, initrd images will be
2706		  copied to the highest possible address in RAM; this
2707		  is usually what you want since it allows for
2708		  maximum initrd size. If for some reason you want to
2709		  make sure that the initrd image is loaded below the
2710		  CFG_BOOTMAPSZ limit, you can set this environment
2711		  variable to a value of "no" or "off" or "0".
2712		  Alternatively, you can set it to a maximum upper
2713		  address to use (U-Boot will still check that it
2714		  does not overwrite the U-Boot stack and data).
2715
2716		  For instance, when you have a system with 16 MB
2717		  RAM, and want to reserve 4 MB from use by Linux,
2718		  you can do this by adding "mem=12M" to the value of
2719		  the "bootargs" variable. However, now you must make
2720		  sure that the initrd image is placed in the first
2721		  12 MB as well - this can be done with
2722
2723		  setenv initrd_high 00c00000
2724
2725		  If you set initrd_high to 0xFFFFFFFF, this is an
2726		  indication to U-Boot that all addresses are legal
2727		  for the Linux kernel, including addresses in flash
2728		  memory. In this case U-Boot will NOT COPY the
2729		  ramdisk at all. This may be useful to reduce the
2730		  boot time on your system, but requires that this
2731		  feature is supported by your Linux kernel.
2732
2733  ipaddr	- IP address; needed for tftpboot command
2734
2735  loadaddr	- Default load address for commands like "bootp",
2736		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2737
2738  loads_echo	- see CONFIG_LOADS_ECHO
2739
2740  serverip	- TFTP server IP address; needed for tftpboot command
2741
2742  bootretry	- see CONFIG_BOOT_RETRY_TIME
2743
2744  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2745
2746  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2747
2748  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2749		  interface is used first.
2750
2751  ethact	- When CONFIG_NET_MULTI is enabled controls which
2752		  interface is currently active. For example you
2753		  can do the following
2754
2755		  => setenv ethact FEC ETHERNET
2756		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2757		  => setenv ethact SCC ETHERNET
2758		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2759
2760  ethrotate	- When set to "no" U-Boot does not go through all
2761		  available network interfaces.
2762		  It just stays at the currently selected interface.
2763
2764   netretry	- When set to "no" each network operation will
2765		  either succeed or fail without retrying.
2766		  When set to "once" the network operation will
2767		  fail when all the available network interfaces
2768		  are tried once without success.
2769		  Useful on scripts which control the retry operation
2770		  themselves.
2771
2772  npe_ucode	- see CONFIG_IXP4XX_NPE_EXT_UCOD
2773		  if set load address for the npe microcode
2774
2775  tftpsrcport	- If this is set, the value is used for TFTP's
2776		  UDP source port.
2777
2778  tftpdstport	- If this is set, the value is used for TFTP's UDP
2779		  destination port instead of the Well Know Port 69.
2780
2781   vlan		- When set to a value < 4095 the traffic over
2782		  ethernet is encapsulated/received over 802.1q
2783		  VLAN tagged frames.
2784
2785The following environment variables may be used and automatically
2786updated by the network boot commands ("bootp" and "rarpboot"),
2787depending the information provided by your boot server:
2788
2789  bootfile	- see above
2790  dnsip		- IP address of your Domain Name Server
2791  dnsip2	- IP address of your secondary Domain Name Server
2792  gatewayip	- IP address of the Gateway (Router) to use
2793  hostname	- Target hostname
2794  ipaddr	- see above
2795  netmask	- Subnet Mask
2796  rootpath	- Pathname of the root filesystem on the NFS server
2797  serverip	- see above
2798
2799
2800There are two special Environment Variables:
2801
2802  serial#	- contains hardware identification information such
2803		  as type string and/or serial number
2804  ethaddr	- Ethernet address
2805
2806These variables can be set only once (usually during manufacturing of
2807the board). U-Boot refuses to delete or overwrite these variables
2808once they have been set once.
2809
2810
2811Further special Environment Variables:
2812
2813  ver		- Contains the U-Boot version string as printed
2814		  with the "version" command. This variable is
2815		  readonly (see CONFIG_VERSION_VARIABLE).
2816
2817
2818Please note that changes to some configuration parameters may take
2819only effect after the next boot (yes, that's just like Windoze :-).
2820
2821
2822Command Line Parsing:
2823=====================
2824
2825There are two different command line parsers available with U-Boot:
2826the old "simple" one, and the much more powerful "hush" shell:
2827
2828Old, simple command line parser:
2829--------------------------------
2830
2831- supports environment variables (through setenv / saveenv commands)
2832- several commands on one line, separated by ';'
2833- variable substitution using "... ${name} ..." syntax
2834- special characters ('$', ';') can be escaped by prefixing with '\',
2835  for example:
2836	setenv bootcmd bootm \${address}
2837- You can also escape text by enclosing in single apostrophes, for example:
2838	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2839
2840Hush shell:
2841-----------
2842
2843- similar to Bourne shell, with control structures like
2844  if...then...else...fi, for...do...done; while...do...done,
2845  until...do...done, ...
2846- supports environment ("global") variables (through setenv / saveenv
2847  commands) and local shell variables (through standard shell syntax
2848  "name=value"); only environment variables can be used with "run"
2849  command
2850
2851General rules:
2852--------------
2853
2854(1) If a command line (or an environment variable executed by a "run"
2855    command) contains several commands separated by semicolon, and
2856    one of these commands fails, then the remaining commands will be
2857    executed anyway.
2858
2859(2) If you execute several variables with one call to run (i. e.
2860    calling run with a list af variables as arguments), any failing
2861    command will cause "run" to terminate, i. e. the remaining
2862    variables are not executed.
2863
2864Note for Redundant Ethernet Interfaces:
2865=======================================
2866
2867Some boards come with redundant ethernet interfaces; U-Boot supports
2868such configurations and is capable of automatic selection of a
2869"working" interface when needed. MAC assignment works as follows:
2870
2871Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2872MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2873"eth1addr" (=>eth1), "eth2addr", ...
2874
2875If the network interface stores some valid MAC address (for instance
2876in SROM), this is used as default address if there is NO correspon-
2877ding setting in the environment; if the corresponding environment
2878variable is set, this overrides the settings in the card; that means:
2879
2880o If the SROM has a valid MAC address, and there is no address in the
2881  environment, the SROM's address is used.
2882
2883o If there is no valid address in the SROM, and a definition in the
2884  environment exists, then the value from the environment variable is
2885  used.
2886
2887o If both the SROM and the environment contain a MAC address, and
2888  both addresses are the same, this MAC address is used.
2889
2890o If both the SROM and the environment contain a MAC address, and the
2891  addresses differ, the value from the environment is used and a
2892  warning is printed.
2893
2894o If neither SROM nor the environment contain a MAC address, an error
2895  is raised.
2896
2897
2898Image Formats:
2899==============
2900
2901The "boot" commands of this monitor operate on "image" files which
2902can be basicly anything, preceeded by a special header; see the
2903definitions in include/image.h for details; basicly, the header
2904defines the following image properties:
2905
2906* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2907  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2908  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2909  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2910* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2911  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2912  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2913* Compression Type (uncompressed, gzip, bzip2)
2914* Load Address
2915* Entry Point
2916* Image Name
2917* Image Timestamp
2918
2919The header is marked by a special Magic Number, and both the header
2920and the data portions of the image are secured against corruption by
2921CRC32 checksums.
2922
2923
2924Linux Support:
2925==============
2926
2927Although U-Boot should support any OS or standalone application
2928easily, the main focus has always been on Linux during the design of
2929U-Boot.
2930
2931U-Boot includes many features that so far have been part of some
2932special "boot loader" code within the Linux kernel. Also, any
2933"initrd" images to be used are no longer part of one big Linux image;
2934instead, kernel and "initrd" are separate images. This implementation
2935serves several purposes:
2936
2937- the same features can be used for other OS or standalone
2938  applications (for instance: using compressed images to reduce the
2939  Flash memory footprint)
2940
2941- it becomes much easier to port new Linux kernel versions because
2942  lots of low-level, hardware dependent stuff are done by U-Boot
2943
2944- the same Linux kernel image can now be used with different "initrd"
2945  images; of course this also means that different kernel images can
2946  be run with the same "initrd". This makes testing easier (you don't
2947  have to build a new "zImage.initrd" Linux image when you just
2948  change a file in your "initrd"). Also, a field-upgrade of the
2949  software is easier now.
2950
2951
2952Linux HOWTO:
2953============
2954
2955Porting Linux to U-Boot based systems:
2956---------------------------------------
2957
2958U-Boot cannot save you from doing all the necessary modifications to
2959configure the Linux device drivers for use with your target hardware
2960(no, we don't intend to provide a full virtual machine interface to
2961Linux :-).
2962
2963But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2964
2965Just make sure your machine specific header file (for instance
2966include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2967Information structure as we define in include/u-boot.h, and make
2968sure that your definition of IMAP_ADDR uses the same value as your
2969U-Boot configuration in CFG_IMMR.
2970
2971
2972Configuring the Linux kernel:
2973-----------------------------
2974
2975No specific requirements for U-Boot. Make sure you have some root
2976device (initial ramdisk, NFS) for your target system.
2977
2978
2979Building a Linux Image:
2980-----------------------
2981
2982With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2983not used. If you use recent kernel source, a new build target
2984"uImage" will exist which automatically builds an image usable by
2985U-Boot. Most older kernels also have support for a "pImage" target,
2986which was introduced for our predecessor project PPCBoot and uses a
2987100% compatible format.
2988
2989Example:
2990
2991	make TQM850L_config
2992	make oldconfig
2993	make dep
2994	make uImage
2995
2996The "uImage" build target uses a special tool (in 'tools/mkimage') to
2997encapsulate a compressed Linux kernel image with header	 information,
2998CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2999
3000* build a standard "vmlinux" kernel image (in ELF binary format):
3001
3002* convert the kernel into a raw binary image:
3003
3004	${CROSS_COMPILE}-objcopy -O binary \
3005				 -R .note -R .comment \
3006				 -S vmlinux linux.bin
3007
3008* compress the binary image:
3009
3010	gzip -9 linux.bin
3011
3012* package compressed binary image for U-Boot:
3013
3014	mkimage -A ppc -O linux -T kernel -C gzip \
3015		-a 0 -e 0 -n "Linux Kernel Image" \
3016		-d linux.bin.gz uImage
3017
3018
3019The "mkimage" tool can also be used to create ramdisk images for use
3020with U-Boot, either separated from the Linux kernel image, or
3021combined into one file. "mkimage" encapsulates the images with a 64
3022byte header containing information about target architecture,
3023operating system, image type, compression method, entry points, time
3024stamp, CRC32 checksums, etc.
3025
3026"mkimage" can be called in two ways: to verify existing images and
3027print the header information, or to build new images.
3028
3029In the first form (with "-l" option) mkimage lists the information
3030contained in the header of an existing U-Boot image; this includes
3031checksum verification:
3032
3033	tools/mkimage -l image
3034	  -l ==> list image header information
3035
3036The second form (with "-d" option) is used to build a U-Boot image
3037from a "data file" which is used as image payload:
3038
3039	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3040		      -n name -d data_file image
3041	  -A ==> set architecture to 'arch'
3042	  -O ==> set operating system to 'os'
3043	  -T ==> set image type to 'type'
3044	  -C ==> set compression type 'comp'
3045	  -a ==> set load address to 'addr' (hex)
3046	  -e ==> set entry point to 'ep' (hex)
3047	  -n ==> set image name to 'name'
3048	  -d ==> use image data from 'datafile'
3049
3050Right now, all Linux kernels for PowerPC systems use the same load
3051address (0x00000000), but the entry point address depends on the
3052kernel version:
3053
3054- 2.2.x kernels have the entry point at 0x0000000C,
3055- 2.3.x and later kernels have the entry point at 0x00000000.
3056
3057So a typical call to build a U-Boot image would read:
3058
3059	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3060	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3061	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3062	> examples/uImage.TQM850L
3063	Image Name:   2.4.4 kernel for TQM850L
3064	Created:      Wed Jul 19 02:34:59 2000
3065	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3066	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3067	Load Address: 0x00000000
3068	Entry Point:  0x00000000
3069
3070To verify the contents of the image (or check for corruption):
3071
3072	-> tools/mkimage -l examples/uImage.TQM850L
3073	Image Name:   2.4.4 kernel for TQM850L
3074	Created:      Wed Jul 19 02:34:59 2000
3075	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3076	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3077	Load Address: 0x00000000
3078	Entry Point:  0x00000000
3079
3080NOTE: for embedded systems where boot time is critical you can trade
3081speed for memory and install an UNCOMPRESSED image instead: this
3082needs more space in Flash, but boots much faster since it does not
3083need to be uncompressed:
3084
3085	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3086	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3087	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3088	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3089	> examples/uImage.TQM850L-uncompressed
3090	Image Name:   2.4.4 kernel for TQM850L
3091	Created:      Wed Jul 19 02:34:59 2000
3092	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3093	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3094	Load Address: 0x00000000
3095	Entry Point:  0x00000000
3096
3097
3098Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3099when your kernel is intended to use an initial ramdisk:
3100
3101	-> tools/mkimage -n 'Simple Ramdisk Image' \
3102	> -A ppc -O linux -T ramdisk -C gzip \
3103	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3104	Image Name:   Simple Ramdisk Image
3105	Created:      Wed Jan 12 14:01:50 2000
3106	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3107	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3108	Load Address: 0x00000000
3109	Entry Point:  0x00000000
3110
3111
3112Installing a Linux Image:
3113-------------------------
3114
3115To downloading a U-Boot image over the serial (console) interface,
3116you must convert the image to S-Record format:
3117
3118	objcopy -I binary -O srec examples/image examples/image.srec
3119
3120The 'objcopy' does not understand the information in the U-Boot
3121image header, so the resulting S-Record file will be relative to
3122address 0x00000000. To load it to a given address, you need to
3123specify the target address as 'offset' parameter with the 'loads'
3124command.
3125
3126Example: install the image to address 0x40100000 (which on the
3127TQM8xxL is in the first Flash bank):
3128
3129	=> erase 40100000 401FFFFF
3130
3131	.......... done
3132	Erased 8 sectors
3133
3134	=> loads 40100000
3135	## Ready for S-Record download ...
3136	~>examples/image.srec
3137	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3138	...
3139	15989 15990 15991 15992
3140	[file transfer complete]
3141	[connected]
3142	## Start Addr = 0x00000000
3143
3144
3145You can check the success of the download using the 'iminfo' command;
3146this includes a checksum verification so you  can  be  sure  no	 data
3147corruption happened:
3148
3149	=> imi 40100000
3150
3151	## Checking Image at 40100000 ...
3152	   Image Name:	 2.2.13 for initrd on TQM850L
3153	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3154	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3155	   Load Address: 00000000
3156	   Entry Point:	 0000000c
3157	   Verifying Checksum ... OK
3158
3159
3160Boot Linux:
3161-----------
3162
3163The "bootm" command is used to boot an application that is stored in
3164memory (RAM or Flash). In case of a Linux kernel image, the contents
3165of the "bootargs" environment variable is passed to the kernel as
3166parameters. You can check and modify this variable using the
3167"printenv" and "setenv" commands:
3168
3169
3170	=> printenv bootargs
3171	bootargs=root=/dev/ram
3172
3173	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3174
3175	=> printenv bootargs
3176	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3177
3178	=> bootm 40020000
3179	## Booting Linux kernel at 40020000 ...
3180	   Image Name:	 2.2.13 for NFS on TQM850L
3181	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3182	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3183	   Load Address: 00000000
3184	   Entry Point:	 0000000c
3185	   Verifying Checksum ... OK
3186	   Uncompressing Kernel Image ... OK
3187	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
3188	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3189	time_init: decrementer frequency = 187500000/60
3190	Calibrating delay loop... 49.77 BogoMIPS
3191	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3192	...
3193
3194If you want to boot a Linux kernel with initial ram disk, you pass
3195the memory addresses of both the kernel and the initrd image (PPBCOOT
3196format!) to the "bootm" command:
3197
3198	=> imi 40100000 40200000
3199
3200	## Checking Image at 40100000 ...
3201	   Image Name:	 2.2.13 for initrd on TQM850L
3202	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3203	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3204	   Load Address: 00000000
3205	   Entry Point:	 0000000c
3206	   Verifying Checksum ... OK
3207
3208	## Checking Image at 40200000 ...
3209	   Image Name:	 Simple Ramdisk Image
3210	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3211	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3212	   Load Address: 00000000
3213	   Entry Point:	 00000000
3214	   Verifying Checksum ... OK
3215
3216	=> bootm 40100000 40200000
3217	## Booting Linux kernel at 40100000 ...
3218	   Image Name:	 2.2.13 for initrd on TQM850L
3219	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3220	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3221	   Load Address: 00000000
3222	   Entry Point:	 0000000c
3223	   Verifying Checksum ... OK
3224	   Uncompressing Kernel Image ... OK
3225	## Loading RAMDisk Image at 40200000 ...
3226	   Image Name:	 Simple Ramdisk Image
3227	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3228	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3229	   Load Address: 00000000
3230	   Entry Point:	 00000000
3231	   Verifying Checksum ... OK
3232	   Loading Ramdisk ... OK
3233	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
3234	Boot arguments: root=/dev/ram
3235	time_init: decrementer frequency = 187500000/60
3236	Calibrating delay loop... 49.77 BogoMIPS
3237	...
3238	RAMDISK: Compressed image found at block 0
3239	VFS: Mounted root (ext2 filesystem).
3240
3241	bash#
3242
3243Boot Linux and pass a flat device tree:
3244-----------
3245
3246First, U-Boot must be compiled with the appropriate defines. See the section
3247titled "Linux Kernel Interface" above for a more in depth explanation. The
3248following is an example of how to start a kernel and pass an updated
3249flat device tree:
3250
3251=> print oftaddr
3252oftaddr=0x300000
3253=> print oft
3254oft=oftrees/mpc8540ads.dtb
3255=> tftp $oftaddr $oft
3256Speed: 1000, full duplex
3257Using TSEC0 device
3258TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3259Filename 'oftrees/mpc8540ads.dtb'.
3260Load address: 0x300000
3261Loading: #
3262done
3263Bytes transferred = 4106 (100a hex)
3264=> tftp $loadaddr $bootfile
3265Speed: 1000, full duplex
3266Using TSEC0 device
3267TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3268Filename 'uImage'.
3269Load address: 0x200000
3270Loading:############
3271done
3272Bytes transferred = 1029407 (fb51f hex)
3273=> print loadaddr
3274loadaddr=200000
3275=> print oftaddr
3276oftaddr=0x300000
3277=> bootm $loadaddr - $oftaddr
3278## Booting image at 00200000 ...
3279   Image Name:	 Linux-2.6.17-dirty
3280   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3281   Data Size:	 1029343 Bytes = 1005.2 kB
3282   Load Address: 00000000
3283   Entry Point:	 00000000
3284   Verifying Checksum ... OK
3285   Uncompressing Kernel Image ... OK
3286Booting using flat device tree at 0x300000
3287Using MPC85xx ADS machine description
3288Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3289[snip]
3290
3291
3292More About U-Boot Image Types:
3293------------------------------
3294
3295U-Boot supports the following image types:
3296
3297   "Standalone Programs" are directly runnable in the environment
3298	provided by U-Boot; it is expected that (if they behave
3299	well) you can continue to work in U-Boot after return from
3300	the Standalone Program.
3301   "OS Kernel Images" are usually images of some Embedded OS which
3302	will take over control completely. Usually these programs
3303	will install their own set of exception handlers, device
3304	drivers, set up the MMU, etc. - this means, that you cannot
3305	expect to re-enter U-Boot except by resetting the CPU.
3306   "RAMDisk Images" are more or less just data blocks, and their
3307	parameters (address, size) are passed to an OS kernel that is
3308	being started.
3309   "Multi-File Images" contain several images, typically an OS
3310	(Linux) kernel image and one or more data images like
3311	RAMDisks. This construct is useful for instance when you want
3312	to boot over the network using BOOTP etc., where the boot
3313	server provides just a single image file, but you want to get
3314	for instance an OS kernel and a RAMDisk image.
3315
3316	"Multi-File Images" start with a list of image sizes, each
3317	image size (in bytes) specified by an "uint32_t" in network
3318	byte order. This list is terminated by an "(uint32_t)0".
3319	Immediately after the terminating 0 follow the images, one by
3320	one, all aligned on "uint32_t" boundaries (size rounded up to
3321	a multiple of 4 bytes).
3322
3323   "Firmware Images" are binary images containing firmware (like
3324	U-Boot or FPGA images) which usually will be programmed to
3325	flash memory.
3326
3327   "Script files" are command sequences that will be executed by
3328	U-Boot's command interpreter; this feature is especially
3329	useful when you configure U-Boot to use a real shell (hush)
3330	as command interpreter.
3331
3332
3333Standalone HOWTO:
3334=================
3335
3336One of the features of U-Boot is that you can dynamically load and
3337run "standalone" applications, which can use some resources of
3338U-Boot like console I/O functions or interrupt services.
3339
3340Two simple examples are included with the sources:
3341
3342"Hello World" Demo:
3343-------------------
3344
3345'examples/hello_world.c' contains a small "Hello World" Demo
3346application; it is automatically compiled when you build U-Boot.
3347It's configured to run at address 0x00040004, so you can play with it
3348like that:
3349
3350	=> loads
3351	## Ready for S-Record download ...
3352	~>examples/hello_world.srec
3353	1 2 3 4 5 6 7 8 9 10 11 ...
3354	[file transfer complete]
3355	[connected]
3356	## Start Addr = 0x00040004
3357
3358	=> go 40004 Hello World! This is a test.
3359	## Starting application at 0x00040004 ...
3360	Hello World
3361	argc = 7
3362	argv[0] = "40004"
3363	argv[1] = "Hello"
3364	argv[2] = "World!"
3365	argv[3] = "This"
3366	argv[4] = "is"
3367	argv[5] = "a"
3368	argv[6] = "test."
3369	argv[7] = "<NULL>"
3370	Hit any key to exit ...
3371
3372	## Application terminated, rc = 0x0
3373
3374Another example, which demonstrates how to register a CPM interrupt
3375handler with the U-Boot code, can be found in 'examples/timer.c'.
3376Here, a CPM timer is set up to generate an interrupt every second.
3377The interrupt service routine is trivial, just printing a '.'
3378character, but this is just a demo program. The application can be
3379controlled by the following keys:
3380
3381	? - print current values og the CPM Timer registers
3382	b - enable interrupts and start timer
3383	e - stop timer and disable interrupts
3384	q - quit application
3385
3386	=> loads
3387	## Ready for S-Record download ...
3388	~>examples/timer.srec
3389	1 2 3 4 5 6 7 8 9 10 11 ...
3390	[file transfer complete]
3391	[connected]
3392	## Start Addr = 0x00040004
3393
3394	=> go 40004
3395	## Starting application at 0x00040004 ...
3396	TIMERS=0xfff00980
3397	Using timer 1
3398	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3399
3400Hit 'b':
3401	[q, b, e, ?] Set interval 1000000 us
3402	Enabling timer
3403Hit '?':
3404	[q, b, e, ?] ........
3405	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3406Hit '?':
3407	[q, b, e, ?] .
3408	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3409Hit '?':
3410	[q, b, e, ?] .
3411	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3412Hit '?':
3413	[q, b, e, ?] .
3414	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3415Hit 'e':
3416	[q, b, e, ?] ...Stopping timer
3417Hit 'q':
3418	[q, b, e, ?] ## Application terminated, rc = 0x0
3419
3420
3421Minicom warning:
3422================
3423
3424Over time, many people have reported problems when trying to use the
3425"minicom" terminal emulation program for serial download. I (wd)
3426consider minicom to be broken, and recommend not to use it. Under
3427Unix, I recommend to use C-Kermit for general purpose use (and
3428especially for kermit binary protocol download ("loadb" command), and
3429use "cu" for S-Record download ("loads" command).
3430
3431Nevertheless, if you absolutely want to use it try adding this
3432configuration to your "File transfer protocols" section:
3433
3434	   Name	   Program			Name U/D FullScr IO-Red. Multi
3435	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3436	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3437
3438
3439NetBSD Notes:
3440=============
3441
3442Starting at version 0.9.2, U-Boot supports NetBSD both as host
3443(build U-Boot) and target system (boots NetBSD/mpc8xx).
3444
3445Building requires a cross environment; it is known to work on
3446NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3447need gmake since the Makefiles are not compatible with BSD make).
3448Note that the cross-powerpc package does not install include files;
3449attempting to build U-Boot will fail because <machine/ansi.h> is
3450missing.  This file has to be installed and patched manually:
3451
3452	# cd /usr/pkg/cross/powerpc-netbsd/include
3453	# mkdir powerpc
3454	# ln -s powerpc machine
3455	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3456	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3457
3458Native builds *don't* work due to incompatibilities between native
3459and U-Boot include files.
3460
3461Booting assumes that (the first part of) the image booted is a
3462stage-2 loader which in turn loads and then invokes the kernel
3463proper. Loader sources will eventually appear in the NetBSD source
3464tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3465meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3466
3467
3468Implementation Internals:
3469=========================
3470
3471The following is not intended to be a complete description of every
3472implementation detail. However, it should help to understand the
3473inner workings of U-Boot and make it easier to port it to custom
3474hardware.
3475
3476
3477Initial Stack, Global Data:
3478---------------------------
3479
3480The implementation of U-Boot is complicated by the fact that U-Boot
3481starts running out of ROM (flash memory), usually without access to
3482system RAM (because the memory controller is not initialized yet).
3483This means that we don't have writable Data or BSS segments, and BSS
3484is not initialized as zero. To be able to get a C environment working
3485at all, we have to allocate at least a minimal stack. Implementation
3486options for this are defined and restricted by the CPU used: Some CPU
3487models provide on-chip memory (like the IMMR area on MPC8xx and
3488MPC826x processors), on others (parts of) the data cache can be
3489locked as (mis-) used as memory, etc.
3490
3491	Chris Hallinan posted a good summary of	 these	issues	to  the
3492	u-boot-users mailing list:
3493
3494	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3495	From: "Chris Hallinan" <clh@net1plus.com>
3496	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3497	...
3498
3499	Correct me if I'm wrong, folks, but the way I understand it
3500	is this: Using DCACHE as initial RAM for Stack, etc, does not
3501	require any physical RAM backing up the cache. The cleverness
3502	is that the cache is being used as a temporary supply of
3503	necessary storage before the SDRAM controller is setup. It's
3504	beyond the scope of this list to expain the details, but you
3505	can see how this works by studying the cache architecture and
3506	operation in the architecture and processor-specific manuals.
3507
3508	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3509	is another option for the system designer to use as an
3510	initial stack/ram area prior to SDRAM being available. Either
3511	option should work for you. Using CS 4 should be fine if your
3512	board designers haven't used it for something that would
3513	cause you grief during the initial boot! It is frequently not
3514	used.
3515
3516	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3517	with your processor/board/system design. The default value
3518	you will find in any recent u-boot distribution in
3519	walnut.h should work for you. I'd set it to a value larger
3520	than your SDRAM module. If you have a 64MB SDRAM module, set
3521	it above 400_0000. Just make sure your board has no resources
3522	that are supposed to respond to that address! That code in
3523	start.S has been around a while and should work as is when
3524	you get the config right.
3525
3526	-Chris Hallinan
3527	DS4.COM, Inc.
3528
3529It is essential to remember this, since it has some impact on the C
3530code for the initialization procedures:
3531
3532* Initialized global data (data segment) is read-only. Do not attempt
3533  to write it.
3534
3535* Do not use any unitialized global data (or implicitely initialized
3536  as zero data - BSS segment) at all - this is undefined, initiali-
3537  zation is performed later (when relocating to RAM).
3538
3539* Stack space is very limited. Avoid big data buffers or things like
3540  that.
3541
3542Having only the stack as writable memory limits means we cannot use
3543normal global data to share information beween the code. But it
3544turned out that the implementation of U-Boot can be greatly
3545simplified by making a global data structure (gd_t) available to all
3546functions. We could pass a pointer to this data as argument to _all_
3547functions, but this would bloat the code. Instead we use a feature of
3548the GCC compiler (Global Register Variables) to share the data: we
3549place a pointer (gd) to the global data into a register which we
3550reserve for this purpose.
3551
3552When choosing a register for such a purpose we are restricted by the
3553relevant  (E)ABI  specifications for the current architecture, and by
3554GCC's implementation.
3555
3556For PowerPC, the following registers have specific use:
3557	R1:	stack pointer
3558	R2:	reserved for system use
3559	R3-R4:	parameter passing and return values
3560	R5-R10: parameter passing
3561	R13:	small data area pointer
3562	R30:	GOT pointer
3563	R31:	frame pointer
3564
3565	(U-Boot also uses R14 as internal GOT pointer.)
3566
3567    ==> U-Boot will use R2 to hold a pointer to the global data
3568
3569    Note: on PPC, we could use a static initializer (since the
3570    address of the global data structure is known at compile time),
3571    but it turned out that reserving a register results in somewhat
3572    smaller code - although the code savings are not that big (on
3573    average for all boards 752 bytes for the whole U-Boot image,
3574    624 text + 127 data).
3575
3576On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3577	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3578
3579    ==> U-Boot will use P5 to hold a pointer to the global data
3580
3581On ARM, the following registers are used:
3582
3583	R0:	function argument word/integer result
3584	R1-R3:	function argument word
3585	R9:	GOT pointer
3586	R10:	stack limit (used only if stack checking if enabled)
3587	R11:	argument (frame) pointer
3588	R12:	temporary workspace
3589	R13:	stack pointer
3590	R14:	link register
3591	R15:	program counter
3592
3593    ==> U-Boot will use R8 to hold a pointer to the global data
3594
3595NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3596or current versions of GCC may "optimize" the code too much.
3597
3598Memory Management:
3599------------------
3600
3601U-Boot runs in system state and uses physical addresses, i.e. the
3602MMU is not used either for address mapping nor for memory protection.
3603
3604The available memory is mapped to fixed addresses using the memory
3605controller. In this process, a contiguous block is formed for each
3606memory type (Flash, SDRAM, SRAM), even when it consists of several
3607physical memory banks.
3608
3609U-Boot is installed in the first 128 kB of the first Flash bank (on
3610TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3611booting and sizing and initializing DRAM, the code relocates itself
3612to the upper end of DRAM. Immediately below the U-Boot code some
3613memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3614configuration setting]. Below that, a structure with global Board
3615Info data is placed, followed by the stack (growing downward).
3616
3617Additionally, some exception handler code is copied to the low 8 kB
3618of DRAM (0x00000000 ... 0x00001FFF).
3619
3620So a typical memory configuration with 16 MB of DRAM could look like
3621this:
3622
3623	0x0000 0000	Exception Vector code
3624	      :
3625	0x0000 1FFF
3626	0x0000 2000	Free for Application Use
3627	      :
3628	      :
3629
3630	      :
3631	      :
3632	0x00FB FF20	Monitor Stack (Growing downward)
3633	0x00FB FFAC	Board Info Data and permanent copy of global data
3634	0x00FC 0000	Malloc Arena
3635	      :
3636	0x00FD FFFF
3637	0x00FE 0000	RAM Copy of Monitor Code
3638	...		eventually: LCD or video framebuffer
3639	...		eventually: pRAM (Protected RAM - unchanged by reset)
3640	0x00FF FFFF	[End of RAM]
3641
3642
3643System Initialization:
3644----------------------
3645
3646In the reset configuration, U-Boot starts at the reset entry point
3647(on most PowerPC systens at address 0x00000100). Because of the reset
3648configuration for CS0# this is a mirror of the onboard Flash memory.
3649To be able to re-map memory U-Boot then jumps to its link address.
3650To be able to implement the initialization code in C, a (small!)
3651initial stack is set up in the internal Dual Ported RAM (in case CPUs
3652which provide such a feature like MPC8xx or MPC8260), or in a locked
3653part of the data cache. After that, U-Boot initializes the CPU core,
3654the caches and the SIU.
3655
3656Next, all (potentially) available memory banks are mapped using a
3657preliminary mapping. For example, we put them on 512 MB boundaries
3658(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3659on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3660programmed for SDRAM access. Using the temporary configuration, a
3661simple memory test is run that determines the size of the SDRAM
3662banks.
3663
3664When there is more than one SDRAM bank, and the banks are of
3665different size, the largest is mapped first. For equal size, the first
3666bank (CS2#) is mapped first. The first mapping is always for address
36670x00000000, with any additional banks following immediately to create
3668contiguous memory starting from 0.
3669
3670Then, the monitor installs itself at the upper end of the SDRAM area
3671and allocates memory for use by malloc() and for the global Board
3672Info data; also, the exception vector code is copied to the low RAM
3673pages, and the final stack is set up.
3674
3675Only after this relocation will you have a "normal" C environment;
3676until that you are restricted in several ways, mostly because you are
3677running from ROM, and because the code will have to be relocated to a
3678new address in RAM.
3679
3680
3681U-Boot Porting Guide:
3682----------------------
3683
3684[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3685list, October 2002]
3686
3687
3688int main (int argc, char *argv[])
3689{
3690	sighandler_t no_more_time;
3691
3692	signal (SIGALRM, no_more_time);
3693	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3694
3695	if (available_money > available_manpower) {
3696		pay consultant to port U-Boot;
3697		return 0;
3698	}
3699
3700	Download latest U-Boot source;
3701
3702	Subscribe to u-boot-users mailing list;
3703
3704	if (clueless) {
3705		email ("Hi, I am new to U-Boot, how do I get started?");
3706	}
3707
3708	while (learning) {
3709		Read the README file in the top level directory;
3710		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3711		Read the source, Luke;
3712	}
3713
3714	if (available_money > toLocalCurrency ($2500)) {
3715		Buy a BDI2000;
3716	} else {
3717		Add a lot of aggravation and time;
3718	}
3719
3720	Create your own board support subdirectory;
3721
3722	Create your own board config file;
3723
3724	while (!running) {
3725		do {
3726			Add / modify source code;
3727		} until (compiles);
3728		Debug;
3729		if (clueless)
3730			email ("Hi, I am having problems...");
3731	}
3732	Send patch file to Wolfgang;
3733
3734	return 0;
3735}
3736
3737void no_more_time (int sig)
3738{
3739      hire_a_guru();
3740}
3741
3742
3743Coding Standards:
3744-----------------
3745
3746All contributions to U-Boot should conform to the Linux kernel
3747coding style; see the file "Documentation/CodingStyle" and the script
3748"scripts/Lindent" in your Linux kernel source directory.  In sources
3749originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3750spaces before parameters to function calls) is actually used.
3751
3752Source files originating from a different project (for example the
3753MTD subsystem) are generally exempt from these guidelines and are not
3754reformated to ease subsequent migration to newer versions of those
3755sources.
3756
3757Please note that U-Boot is implemented in C (and to some small parts in
3758Assembler); no C++ is used, so please do not use C++ style comments (//)
3759in your code.
3760
3761Please also stick to the following formatting rules:
3762- remove any trailing white space
3763- use TAB characters for indentation, not spaces
3764- make sure NOT to use DOS '\r\n' line feeds
3765- do not add more than 2 empty lines to source files
3766- do not add trailing empty lines to source files
3767
3768Submissions which do not conform to the standards may be returned
3769with a request to reformat the changes.
3770
3771
3772Submitting Patches:
3773-------------------
3774
3775Since the number of patches for U-Boot is growing, we need to
3776establish some rules. Submissions which do not conform to these rules
3777may be rejected, even when they contain important and valuable stuff.
3778
3779Patches shall be sent to the u-boot-users mailing list.
3780
3781When you send a patch, please include the following information with
3782it:
3783
3784* For bug fixes: a description of the bug and how your patch fixes
3785  this bug. Please try to include a way of demonstrating that the
3786  patch actually fixes something.
3787
3788* For new features: a description of the feature and your
3789  implementation.
3790
3791* A CHANGELOG entry as plaintext (separate from the patch)
3792
3793* For major contributions, your entry to the CREDITS file
3794
3795* When you add support for a new board, don't forget to add this
3796  board to the MAKEALL script, too.
3797
3798* If your patch adds new configuration options, don't forget to
3799  document these in the README file.
3800
3801* The patch itself. If you are accessing the CVS repository use "cvs
3802  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3803  version of diff does not support these options, then get the latest
3804  version of GNU diff.
3805
3806  The current directory when running this command shall be the top
3807  level directory of the U-Boot source tree, or it's parent directory
3808  (i. e. please make sure that your patch includes sufficient
3809  directory information for the affected files).
3810
3811  We accept patches as plain text, MIME attachments or as uuencoded
3812  gzipped text.
3813
3814* If one logical set of modifications affects or creates several
3815  files, all these changes shall be submitted in a SINGLE patch file.
3816
3817* Changesets that contain different, unrelated modifications shall be
3818  submitted as SEPARATE patches, one patch per changeset.
3819
3820
3821Notes:
3822
3823* Before sending the patch, run the MAKEALL script on your patched
3824  source tree and make sure that no errors or warnings are reported
3825  for any of the boards.
3826
3827* Keep your modifications to the necessary minimum: A patch
3828  containing several unrelated changes or arbitrary reformats will be
3829  returned with a request to re-formatting / split it.
3830
3831* If you modify existing code, make sure that your new code does not
3832  add to the memory footprint of the code ;-) Small is beautiful!
3833  When adding new features, these should compile conditionally only
3834  (using #ifdef), and the resulting code with the new feature
3835  disabled must not need more memory than the old code without your
3836  modification.
3837
3838* Remember that there is a size limit of 40 kB per message on the
3839  u-boot-users mailing list. Compression may help.
3840