#
# (C) Copyright 2000
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# See file CREDITS for list of people who contributed to this
# project.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#

Summary:
========

This directory contains the source code for PPCBoot, a monitor for
Embedded PowerPC boards, which can be installed in a boot ROM and
used to test the hardware or download and run application code.

The development of PPCBoot is closely related to Linux: some parts of
the source code originate in the Linux source tree, we still have
some header files in common, and special provision has been made to
support booting of Linux images.

Some attention has been paid to make this software easily
configurable and extendable. For instance, all monitor commands are
implemented with the same call interface, so that it's very easy to
add new commands. Also, instead of permanently adding rarely used
code (for instance hardware test utilities) to the monitor, you can
load and run it dynamically.


Status:
=======

In general, all boards for which a configuration option exists in the
Makefile have been tested  to  some  extend  and  can  be  sonsidered
"working". In fact, many of them are used in production systems.

In case of problems see the CHANGELOG and CREDITS files to  find  out
who contributed the specific port.

Exception from this rule: the port to the Sandpoint 8240 has not been
completed yet.


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

In case you have questions about, problems with or contributions  for
PPCBoot  you  should  send  a  message to the PPCBoot mailing list at
<ppcboot-users@lists.sourceforge.net>. There is also  an  archive  of
previous  traffic  on  the  mailing  list - please search the archive
before asking FAQ's. Please see
http://lists.sourceforge.net/lists/listinfo/ppcboot-users/


Where we come from:
===================

- start from 8xxrom sources
- clean up code
- make it easier to add custom boards
- eventually make it possible to add other [PowerPC] CPUs
- extend functions, especially:
  * Provide extended interface to Linux boot loader
  * S-Record download
  * network boot
  * PCMCIA / CompactFLash / ATA disk boot


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

- board		Board dependend files
- common	Misc architecture independend functions
- cpu		CPU specificfiles
- doc		Documentation (don't expect too much)
- examples	Example code for standalone applications, etc.
- include	Header Files
- disk		Harddisk interface code
- net		Networking code
- ppc		Files generic to PowerPC architecture
- tools		Tools to build S-Record or PPCBoot images, etc.

- cpu/mpc8xx	Files specific to Motorola MPC8xx  CPUs
- cpu/mpc8240	Files specific to Motorola MPC8240 CPU
- cpu/mpc8260	Files specific to Motorola MPC8260 CPU
- cpu/mpc74xx	Files specific to Motorola MPC74xx CPUs
- cpu/ppc4xx	Files specific to IBM	   4xx	   CPUs

- board/cogent	Files specific to Cogent     boards
		(need further configuration)
		Files specific to CPCIISER4  boards
- board/cu824	Files specific to CU824      boards
- board/eric	Files specific to ERIC	     boards
- board/esd/	Files specific to boards manufactured by ESD
- board/esd/adciop	Files specific to ADCIOP     boards
- board/esd/ar405	Files specific to AR405      boards
- board/esd/canbt	Files specific to CANBT      boards
- board/esd/cpci405	Files specific to CPCI405    boards
- board/esd/cpciiser4	Files specific to CPCIISER4  boards
- board/esd/common	Common files for ESD boards
- board/esteem192e
		Files specific to ESTEEM192E boards
- board/etx094	Files specific to ETX_094    boards
- board/evb64260
		Files specific to EVB64260   boards
- board/fads	Files specific to FADS	     boards
- board/flagadm	Files specific to FLAGADM    boards
- board/genietv Files specific to GENIETV    boards
- board/gth	Files specific to GTH        boards
- board/hermes	Files specific to HERMES     boards
- board/hymod	Files specific to HYMOD	     boards
- board/ip860	Files specific to IP860	     boards
- board/ivms8	Files specific to IVMS8/IVML24 boards
- board/lantec	Files specific to LANTEC     boards
- board/lwmon	Files specific to LWMON      boards
- board/mbx8xx	Files specific to MBX	     boards
- board/pip405	Files specific to PIP405     boards
- board/RPXlite Files specific to RPXlite    boards
- board/rpxsuper
		Files specific to RPXsuper   boards
- board/rsdproto
		Files specific to RSDproto   boards
- board/sandpoint
		Files specific to Sandpoint  boards
- board/siemens Files specific to boards manufactured by Siemens AG
- board/siemens/CCM	Files specific to CCM        boards
- board/siemens/pcu_e	Files specific to PCU_E      boards
- board/sbc8260	Files specific to BC8260     boards

- board/sixnet	Files specific to SIXNET     boards
- board/spd8xx	Files specific to SPD8xxTS   boards
- board/tqm8260	Files specific to TQM8260    boards
- board/tqm8xx	Files specific to TQM8xxL    boards
- board/walnut405
		Files specific to Walnut405  boards


Software Configuration:
=======================

Configuration is usually done using C preprocessor defines; the
rationale behind that is to avoid dead code whenever possible.

There are two classes of configuration variables:

* Configuration _OPTIONS_:
  These are selectable by the user and have names beginning with
  "CONFIG_".

* Configuration _SETTINGS_:
  These depend on the hardware etc. and should not be meddled with if
  you don't know what you're doing; they have names beginning with
  "CFG_".

Later we will add a configuration tool - probably similar to or even
identical to what's used for the Linux kernel. Right now, we have to
do the configuration by hand, which means creating some symbolic
links and editing some configuration files. We use the TQM8xxL boards
as an example here.


Selection of Processor Architecture and Board Type:
---------------------------------------------------

For all supported boards there are ready-to-use default
configurations available; just type "make <board_name>_config".

Example: For a TQM823L module type:

	cd ppcboot
	make TQM823L_config

For the Cogent platform, you need to specify the cpu type as well;
e.g. "make cogent_mpc8xx_config". And also configure the cogent
directory according to the instructions in cogent/README.


Configuration Options:
----------------------

Configuration depends on the combination of board and CPU type; all
such information is kept in a configuration file
"include/config_<board_name>.h".

Example: For a TQM823L module, all configuration settings are in
"include/config_TQM823L.h".


The following options need to be configured:

- CPU Type:	Define exactly one of
		CONFIG_MPC823,	CONFIG_MPC850,	CONFIG_MPC855,	CONFIG_MPC860
	or	CONFIG_MPC8240, CONFIG_MPC8260
	or	CONFIG_IOP480
	or	CONFIG_405GP
	or	CONFIG_MPC74xx

- Board Type:	Define exactly one of

		CONFIG_ADCIOP,      CONFIG_FADS,        CONFIG_RPXSUPER,
		CONFIG_ADS,         CONFIG_FPS850L,     CONFIG_SANDPOINT,
		CONFIG_BSEIP,       CONFIG_HERMES,      CONFIG_SBC8260,
		CONFIG_COGENT,      CONFIG_HYMOD,       CONFIG_SM850,
		CONFIG_COGENT,      CONFIG_IP860,       CONFIG_SPD823TS,
		CONFIG_CPCI405,     CONFIG_IVMS8,       CONFIG_SXNI855T,
		CONFIG_CU824,       CONFIG_MBX,         CONFIG_TQM823L,
		CONFIG_ERIC,        CONFIG_PIP405,      CONFIG_TQM8260,
		CONFIG_ETX094,      CONFIG_RDSPROTO,    CONFIG_TQM850L,
		CONFIG_EVB64260,    CONFIG_RPXCLASSIC,  CONFIG_TQM855L,
		CONFIG_EVB64260,    CONFIG_RPXLITE,     CONFIG_TQM860L,
		CONFIG_PCU_E,	    CONFIG_CCM

- CPU Module Type: (if CONFIG_COGENT is defined)
		Define exactly one of
		CONFIG_CMA286_60_OLD
--- FIXME --- not tested yet:
		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
		CONFIG_CMA287_23, CONFIG_CMA287_50

- Motherboard Type: (if CONFIG_COGENT is defined)
		Define exactly one of
		CONFIG_CMA101, CONFIG_CMA102

- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
		Define one or more of
		CONFIG_CMA302

- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
		Define one or more of
		CONFIG_LCD_HEARTBEAT	- update a character position on
					  the lcd display every second with
					  a "rotator" |\-/|\-/

- 8xx CPU Options: (if using an 8xx cpu)
		Define one or more of
		CONFIG_8xx_GCLK_FREQ	- if get_gclk_freq() can not work e.g.
					  no 32KHz reference PIT/RTC clock

- Clock Interface:
		CONFIG_CLOCKS_IN_MHZ

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

                When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
                "clocks_in_mhz=1" is  automatically  included  in  the
                default environment.

- Console Interface:
		Define exactly one of
		CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2 or
		CONFIG_8xx_CONS_NONE

		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
		port routines must be defined elsewhere
		(i.e. serial_init(), serial_getc(), ...)

- Console Baudrate:
		CONFIG_BAUDRATE - in bps
		Select one of the baudrates listed in
		CFG_BAUDRATE_TABLE, see below.

- Interrupt driven serial port input:
		CONFIG_SERIAL_SOFTWARE_FIFO

		PPC405GP only.
                Use an interrupt handler for receiving data on the
                serial port. It also enables using hardware handshake
                (RTS/CTS) and UART's built-in FIFO. Set the number of
                bytes the interrupt driven input buffer should have.

		Set to 0 to disable this feature (this is the default).
		This will also disable hardware handshake.

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

		See doc/README.autoboot for these options that
		work with CONFIG_BOOTDELAY. None are required.
		CONFIG_BOOT_RETRY_TIME
		CONFIG_BOOT_RETRY_MIN
		CONFIG_AUTOBOOT_KEYED
		CONFIG_AUTOBOOT_PROMPT
		CONFIG_AUTOBOOT_DELAY_STR
		CONFIG_AUTOBOOT_STOP_STR
		CONFIG_ZERO_BOOTDELAY_CHECK
		CONFIG_RESET_TO_RETRY

- Autoboot Command:
		CONFIG_BOOTCOMMAND
		Only needed when CONFIG_BOOTDELAY is enabled;
		define a command string that is automatically executed
		when no character is read on the console interface
		withing "Boot Delay" after reset.

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

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

- Pre-Boot Commands:
		CONFIG_PREBOOT

                When this option is #defined, the existence of the
                environment variable "preboot" will be checked
                immediately before starting the CONFIG_BOOTDELAY
                countdown and/or running the auto-boot command resp.
                entering interactive mode.

                This feature is especially useful when "preboot" is
                automatically generated or modified. For an example
                see the LWMON board specific code: here "preboot" is
                modified when the user holds down a certain
                combination of keys on the (special) keyboard when
                booting the systems

- Serial Download Echo Mode:
		CONFIG_LOADS_ECHO
		If defined to 1, all characters received during a
		serial download (using the "loads" command) are
		echoed back. This might be needed by some terminal
		emulations (like "cu"), but may as well just take
		time on others. This setting #define's the initial
		value of the "loads_echo" environment variable.

- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
		CONFIG_KGDB_BAUDRATE
		Select one of the baudrates listed in
		CFG_BAUDRATE_TABLE, see below.

- Monitor Functions:
		CONFIG_COMMANDS
		Most monitor functions can be selected (or
		de-selected) by adjusting the definition of
		CONFIG_COMMANDS; to select individual functions,
		#define CONFIG_COMMANDS by "OR"ing any of the
		following values:

		#define enables commands:
		-------------------------
		CFG_CMD_BDI	  bdinfo
		CFG_CMD_LOADS	  loads
		CFG_CMD_LOADB	  loadb
		CFG_CMD_IMI	  iminfo
		CFG_CMD_CACHE	  icache, dcache
		CFG_CMD_FLASH	  flinfo, erase, protect
		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
				  loop, mtest
		CFG_CMD_NET	  bootp, tftpboot, rarpboot
		CFG_CMD_ENV	  saveenv
		CFG_CMD_KGDB	* kgdb
		CFG_CMD_PCMCIA	* PCMCIA support
		CFG_CMD_IDE	* IDE harddisk support
		CFG_CMD_PCI	* pciinfo
		CFG_CMD_IRQ	* irqinfo
		CFG_CMD_BOOTD	  bootd
		CFG_CMD_CONSOLE	  coninfo
		CFG_CMD_EEPROM	* EEPROM read/write support
		CFG_CMD_ASKENV	* ask for env variable
		CFG_CMD_RUN	  run command in env variable
		CFG_CMD_ECHO	* echo arguments
		CFG_CMD_I2C	* I2C serial bus support
		CFG_CMD_REGINFO * Register dump
		CFG_CMD_IMMAP	* IMMR dump support
		CFG_CMD_DATE	* support for RTC, date/time...
		CFG_CMD_DHCP	  DHCP support
		CFG_CMD_BEDBUG	  Include BedBug Debugger
		CFG_CMD_FDC	  Floppy Disk Support
		CFG_CMD_SCSI	  SCSI Support
		CFG_CMD_BSP	* Board SPecific functions
		-----------------------------------------------
		CFG_CMD_ALL	all

		CFG_CMD_DFL	Default configuration; at the moment
				this is includes all commands, except
				the ones marked with "*" in the list
				above.

		If you don't define CONFIG_COMMANDS it defaults to
		CFG_CMD_DFL in include/cmd_confdefs.h. A board can
		override the default settings in the respective
		include file.

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

		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)

- Watchdog:
		CONFIG_WATCHDOG
		If this variable is defined, it enables watchdog
		support. There must support in the platform specific
		code for a watchdog. For the 8xx and 8260 CPUs, the
		SIU Watchdog feature is enabled in the SYPCR
		register.

- Real-Time Clock:

                When CFG_CMD_DATE is selected, the type of the RTC
                has to be selected, too. Define exactly one of the
                following options:

		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
		CONFIG_RTC_MC146818	- use MC146818 RTC

- Partition Support:
		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
		and/or CONFIG_ISO_PARTITION

                If IDE or SCSI support  is  enabled  (CFG_CMD_IDE  or
                CFG_CMD_SCSI) you must configure support for at least
                one partition type as well.

- IDE Reset method:
		CONFIG_IDE_RESET_ROUTINE

                Set this to define that instead of a reset Pin, the
                routine ide_set_reset(int idereset) will be used.

- ATAPI Support:
		CONFIG_ATAPI

		Set this to enable ATAPI support.

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

                CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
                CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
                CFG_SCSI_MAX_LUN] can be adjusted to define the
                maximum numbers of LUNs, SCSI ID's and target
                devices.

- Keyboard Support:
		CONFIG_ISA_KEYBOARD

                Define this to enable standard (PC-Style) keyboard
		support

- Video support:
		CONFIG_VIDEO

                Define this to enable  video  support  (for  instance
		output to LCD).

		CONFIG_VIDEO_CT69000

		Enable Chips & Technologies 69000 Video chip

- Ethernet address:
		CONFIG_ETHADDR
		CONFIG_ETH2ADDR
		CONFIG_ETH3ADDR

                Define a default value for ethernet address to use
                for the respective ethernet interface, in case this
                is not determined automatically.

- IP address:
		CONFIG_IPADDR

                Define a default value for the IP address to use for
                the default ethernet interface, in case this is not
                determined through e.g. bootp.

- Server IP address:
		CONFIG_SERVERIP

                Defines a default value for theIP address of a TFTP
                server to contact when using the "tftboot" command.

- BOOTP Recovery Mode:
		CONFIG_BOOTP_RANDOM_DELAY

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

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

- Status LED:	CONFIG_STATUS_LED

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

- CAN Support:	CONFIG_CAN_DRIVER

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

- I2C Support:	CONFIG_I2C

		Enables I2C driver

		CONFIG_I2C_X

		Enables extended (16-bit) I2C addressing.

		CONFIG_SOFT_I2C

                Use software (aka bit-banging) driver instead of CPM
                or similar hardware support for I2C

- SPI Support:	CONFIG_SPI

		Enables SPI driver (so far only tested with
		SPI EEPROM)

		CONFIG_SPI_X

		Enables extended (16-bit) SPI EEPROM addressing.
		(symmetrical to CONFIG_I2C_X)

- Configuration Management:
		CONFIG_IDENT_STRING

                If defined, this string will be added to the PPCBoot
                version information (PPCBOOT_VERSION)

- Vendor Parameter Protection:
                
                PPCBoot considers the values of the environment
                variables "serial#" (Board Serial Number) and
                "ethaddr" (Ethernet Address) to bb parameters that
                are set once by the board vendor / manufacturer, and
                protects these variables from casual modification by
                the user. Once set, these variables are read-only,
                and write or delete attempts are rejected. You can
                change this behviour:

                If CONFIG_ENV_OVERWRITE is #defined in your config
                file, the write protection for vendor parameters is
                completely disabled. Anybody can change or delte
                these parameters.

                Alternatively, if you #define _both_ CONFIG_ETHADDR
                _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
                ethernet address is installed in the environment,
                which can be changed exactly ONCE by the user. [The
                serial# is unaffected by this, i. e. it remains
                read-only.]

- Protected RAM:
		CONFIG_PRAM

                Define this variable to enable the reservation of
                "protected RAM", i. e. RAM which is not overwritten
                by PPCBoot. Define CONFIG_PRAM to hold the number of
                kB you want to reserve for pRAM. You can overwrite
                this default value by defining an environment
                variable "pram" to the number of kB you want to
                reserve. Note that the board info structure will
                still show the full amount of RAM. If pRAM is
                reserved, a new environment variable "mem" will
                automatically be defined to hold the amount of
                remaining RAM in a form that can be passed as boot
                argument to Linux, for instance like that:

			setenv bootargs ... mem=\$(mem)
			saveenv

                This way you can tell Linux not to use this memory,
                either, which results in a memory region that will
                not be affected by reboots.

                *WARNING* If your board configuration uses automatic
                detection of the RAM size, you must make sure that
                this memory test is non-destructive. So far, the
                following board configurations are known to be
                "pRAM-clean":

			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
			HERMES, IP860, RPXlite, LWMON, LANTEC,
			PCU_E, FLAGADM, TQM8260

- Error Recovery:
		CONFIG_PANIC_HANG

                Define this variable to stop the system in case of a
                fatal error, so that you have to reset it manually.
                This is probably NOT a good idea for an embedded
                system where you want to system to reboot
                automatically as fast as possible, but it may be
                useful during development since you can try to debug
                the conditions that lead to the situation.

Configuration Settings:
-----------------------

- CFG_LONGHELP: Defined when you want long help messages included;
		undefine this when you're short of memory.

- CFG_PROMPT:	This is what PPCBoot prints on the console to
		prompt for user input.

- CFG_CBSIZE:	Buffer size for input from the Console

- CFG_PBSIZE:	Buffer size for Console output

- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands

- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
		the application (usually a Linux kernel) when it is
		bootet

- CFG_BAUDRATE_TABLE:
		List of legal baudrate settings for this board.

- CFG_MEMTEST_START, CFG_MEMTEST_END:
		Begin and End addresses of the area used by the
		simple memory test.

- CFG_TFTP_LOADADDR:
		Default load address for network file downloads

- CFG_LOADS_BAUD_CHANGE:
		Enable temporary baudrate change while serial download

- CFG_SDRAM_BASE:
		Physical start address of SDRAM. _Must_ be 0 here.

- CFG_MBIO_BASE:
		Physical start address of Motherboard I/O (if using a
		Cogent motherboard)

- CFG_FLASH_BASE:
		Physical start address of Flash memory.

- CFG_MONITOR_BASE:
		Physical start address of boot monitor code (set by
		make config files to be same as the text base address
		(TEXT_BASE) used when linking) - same as
		CFG_FLASH_BASE when booting from flash.

- CFG_MONITOR_LEN:
		Size of memory reserved for monitor code

- CFG_MALLOC_LEN:
		Size of DRAM reserved for malloc() use.

- CFG_BOOTMAPSZ:
		Maximum size of memory mapped by the startup code of
		the Linux kernel; all data that must be processed by
		the Linux kernel (bd_info, boot arguments, eventually
		initrd image) must be put below this limit.

- CFG_MAX_FLASH_BANKS:
		Max number of Flash memory banks

- CFG_MAX_FLASH_SECT:
		Max number of sectors on a Flash chip

- CFG_FLASH_ERASE_TOUT:
		Timeout for Flash erase operations (in ms)

- CFG_FLASH_WRITE_TOUT:
		Timeout for Flash write operations (in ms)


The following definitions that deal with the placement and management
of environment data (variable area); in general, we support the
following configurations:

- CFG_ENV_IS_IN_FLASH:

	Define this if the environment is in flash memory.

	a) The environment occupies one whole flash sector, which is
	   "embedded" in the text segment with the PPCBoot code. This
	   happens usually with "bottom boot sector" or "top boot
	   sector" type flash chips, which have several smaller
	   sectors at the start or the end. For instance, such a
	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
	   such a case you would place the environment in one of the
	   4 kB sectors - with PPCBoot code before and after it. With
	   "top boot sector" type flash chips, you would put the
	   environment in one of the last sectors, leaving a gap
	   between PPCBoot and the environment.

	- CFG_ENV_OFFSET:

	   Offset of environment data (variable area) to the
	   beginning of flash memory; for instance, with bottom boot
	   type flash chips the second sector can be used: the offset
	   for this sector is given here.

	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.

	- CFG_ENV_ADDR:

	   This is just another way to specify the start address of
	   the flash sector containing the environment (instead of
	   CFG_ENV_OFFSET).

	- CFG_ENV_SECT_SIZE:

	   Size of the sector containing the environment.


	b) Sometimes flash chips have few, equal sized, BIG sectors.
	   In such a case you don't want to spend a whole sector for
	   the environment.

	- CFG_ENV_SIZE:

	   If you use this in combination with CFG_ENV_IS_IN_FLASH
	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
	   of this flash sector for the environment. This saves
	   memory for the RAM copy of the environment.

	   It may also save flash memory if you decide to use this
	   when your environment is "embedded" within PPCBoot code,
	   since then the remainder of the flash sector could be used
	   for PPCBoot code. It should be pointed out that this is
	   STRONGLY DISCOURAGED from a robustness point of view:
	   updating the environment in flash makes it always
	   necessary to erase the WHOLE sector. If something goes
	   wrong before the contents has been restored from a copy in
	   RAM, your target system will be dead.


BE CAREFUL! Any changes to the flash layout, and some changes to the
source code will make it necessary to adapt <board>/ppcboot.lds*
accordingly!


- CFG_ENV_IS_IN_NVRAM:

	Define this if you have some non-volatile memory device
	(NVRAM, battery buffered SRAM) which you want to use for the
	environment.

	- CFG_ENV_ADDR:
	- CFG_ENV_SIZE:

	  These two #defines are used to determin the memory area you
	  want to use for environment. It is assumed that this memory
	  can just be read and written to, without any special
	  provision.

BE CAREFUL! The first access to the environment happens quite early
in PPCboot initalization (when we try to get the setting of for the
console baudrate). You *MUST* have mappend your NVRAM area then, or
PPCBoot will hang.

Please note that even with NVRAM we still use a copy of the
environment in RAM: we could work on NVRAM directly, but we want to
keep settings there always unmodified except somebody uses "saveenv"
to save the current settings.


- CFG_ENV_IS_IN_EEPROM:

	Use this if you have an EEPROM or similar serial access
	device and a driver for it.

	- CFG_ENV_OFFSET:
	- CFG_ENV_SIZE:

	  These two #defines specify the offset and size of the
	  environment area within the total memory of your EEPROM.

- CFG_SPI_INIT_OFFSET

        Defines offset to the initial SPI buffer area in DPRAM. The
        area is used at an early stage (ROM part) if the environment
        is configured to reside in the SPI EEPROM: We need a 520 byte
        scratch DPRAM area. It is used between the two initialization
        calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
        to be a good choice since it makes it far enough from the
        start of the data area as well as from the stack pointer.

Please note that the environment is read-only as long as the monitor
has been relocated to RAM and a RAM copy of the environment has been
created; also, when using EEPROM you will have to use getenv_r()
until then to read environment variables.

The environment is now protected by a CRC32 checksum. Before the
monitor is relocated into RAM, as a result of a bad CRC you will be
working with the compiled-in default environment - *silently*!!!
[This is necessary, because the first environment variable we need is
the "baudrate" setting for the console - if we have a bad CRC, we
don't have any device yet where we could complain.]

Note: once the monitor has been relocated, then it will complain if
the default environment is used; a new CRC is computed as sson as you
use the "setenv" command to modify / delete / add any environment
variable [even when you try to delete a non-existing variable!].

Note2: you must edit your ppcboot.lds file to reflect this
configuration.


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

Low Level (hardware related) configuration options:

- CFG_CACHELINE_SIZE:
		Cache Line Size of the CPU.

- CFG_DEFAULT_IMMR:
                Default address of the IMMR after system reset.
                Needed on some 8260 systems (MPC8260ADS and RPXsuper)
                to be able to adjust the position of the IMMR
                register after a reset.

- CFG_IMMR:	Physical address of the Internal Memory Mapped
		Register; DO NOT CHANGE! (11-4)
		[MPC8xx systems only]

- CFG_INIT_RAM_ADDR:

                Start address of memory area tha can be used for
                initial data and stack; please note that this mus be
                writable memory that is working WITHOUT special
                initialization, i. e. you CANNOT use normal RAM which
                will become available only after programming the
                memory controller and running certain initialization
                sequences.

		PPCBoot uses the followinbg memory types:
                - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
		- MPC8240: data cache

- CFG_INIT_DATA_OFFSET:

                Offset of the initial data structure in the memory
                area defined by CFG_INIT_RAM_ADDR. Usually
                CFG_INIT_DATA_OFFSET is chosen such that the initial
                data is located at the end of the available space
                (sometimes written as (CFG_INIT_RAM_END -
                CFG_INIT_DATA_SIZE), and the initial stack is just
                below that area (growing from (CFG_INIT_RAM_ADDR +
                CFG_INIT_DATA_OFFSET) downward.

	Note:
                On the MPC8240 (or other systems that use the data
                cache for initial memory) the address chosen for
                CFG_INIT_RAM_ADDR is basically arbitrary - it must
                point to an otherwise UNUSED address space between
                the top of RAM and the start of the PCI space.

- CFG_SIUMCR:	SIU Module Configuration (11-6)

- CFG_SYPCR:	System Protection Control (11-9)

- CFG_TBSCR:	Time Base Status and Control (11-26)

- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)

- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)

- CFG_SCCR:	System Clock and reset Control Register (15-27)

- CFG_OR_TIMING_SDRAM:
		SDRAM timing

- CFG_MAMR_PTA:
		periodic timer for refresh

- CFG_DER:	Debug Event Register (37-47)

- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
  CFG_BR1_PRELIM:
		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)

- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)

- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
		Machine Mode Register and Memory Periodic Timer
		Prescaler definitions (SDRAM timing)

- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
		enable I2C microcode relocation patch (MPC8xx);
		define relocation offset in DPRAM [DSP2]

- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
		enable SPI microcode relocation patch (MPC8xx);
		define relocation offset in DPRAM [SCC4]


Building the Software:
======================

Building PPCBoot has been tested in native PPC environments (on a
PowerBook G3 running LinuxPPC 2000) and in cross environments
(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
NetBSD 1.5 on x86).

If you are not using a native PPC environment, it is assumed that you
have the GNU cross compiling tools available in your path and named
with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
change it to:

	CROSS_COMPILE = ppc_4xx-


PPCBoot is intended to be  simple  to  build.  After  installing  the
sources	 you must configure PPCBoot for one specific board type. This
is done by typing:

	make NAME_config

where "NAME_config" is the name of one of the existing
configurations; the following names are supported:

    ADCIOP_config         GTH_config            TQM850L_config
    ADS860_config         IP860_config          TQM855L_config
    AR405_config          IVML24_config         TQM860L_config
    CANBT_config          IVMS8_config          WALNUT405_config
    CPCI405_config        LANTEC_config         cogent_common_config
    CPCIISER4_config      MBX_config            cogent_mpc8260_config
    CU824_config          MBX860T_config        cogent_mpc8xx_config
    ESTEEM192E_config     RPXlite_config        hermes_config
    ETX094_config         RPXsuper_config       hymod_config
    FADS823_config        SM850_config          lwmon_config
    FADS850SAR_config     SPD823TS_config       pcu_e_config
    FADS860T_config       SXNI855T_config       rsdproto_config
    FPS850L_config        Sandpoint8240_config  sbc8260_config
    GENIETV_config        TQM823L_config	PIP405_config

Finally, type "make all", and you should  get  some  working  PPCBoot
images ready for downlod to / installation on your system:

- "ppcboot.bin" is a raw binary image
- "ppcboot" is an image in ELF binary format
- "ppcboot.srec" is in Motorola S-Record format


Please be aware that the Makefiles assume you are using GNU make, so
for instance on NetBSD you might need to use "gmake" instead of
native "make".


If the system board that you have is not listed, then you will need
to port PPCBoot to your hardware platform. To do this, follow these
steps:

1.  Add a new configuration option for your board to the toplevel
    "Makefile", using the existing entries as examples.
2.  Create a new directory to hold your board specific code. Add any
    files you need.
3.  If you're porting PPCBoot to a new CPU, then also create a new
    directory to hold your CPU specific code. Add any files you need.
4.  Run "make config_name" with your new name.
5.  Type "make", and you should get a working "ppcboot.srec" file
    to be installed on your target system.
    [Of course, this last step is much harder than it sounds.]



Monitor Commands - Overview:
============================

go	- start application at address 'addr'
run	- run commands in an environment variable
bootm	- boot application image from memory
bootp	- boot image via network using BootP/TFTP protocol
tftpboot- boot image via network using TFTP protocol
	       and env variables ipaddr and serverip
rarpboot- boot image via network using RARP/TFTP protocol
diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
loads	- load S-Record file over serial line
loadb	- load binary file over serial line (kermit mode)
md	- memory display
mm	- memory modify (auto-incrementing)
nm	- memory modify (constant address)
mw	- memory write (fill)
cp	- memory copy
cmp	- memory compare
crc32	- checksum calculation
base	- print or set address offset
printenv- print environment variables
setenv	- set environment variables
saveenv - save environment variables to persistent storage
protect - enable or disable FLASH write protection
erase	- erase FLASH memory
flinfo	- print FLASH memory information
bdinfo	- print Board Info structure
iminfo	- print header information for application image
coninfo - print console devices and informations
ide	- IDE sub-system
loop	- infinite loop on address range
mtest	- simple RAM test
icache	- enable or disable instruction cache
dcache	- enable or disable data cache
reset	- Perform RESET of the CPU
echo	- echo args to console
version - print monitor version
help	- print online help
?	- alias for 'help'


Monitor Commands - Detailed Description:
========================================

TODO.

For now: just type "help <command>".


Environment Variables:
======================

PPCBoot supports user configuration using Environment Variables which
can be made persistent by saving to Flash memory.

Environment Variables are set using "setenv", printed using
"printenv", and saved to Flash using "saveenv". Using "setenv"
without a value can be used to delete a variable from the
environment. As long as you don't save the environment you are
working with an in-memory copy. In case the Flash area containing the
environment is erased by accident, a default environment is provided.

Some configuration options can be set using Environment Variables:

  baudrate	- see CONFIG_BAUDRATE

  bootdelay	- see CONFIG_BOOTDELAY

  bootcmd	- see CONFIG_BOOTCOMMAND

  bootargs	- Boot arguments when booting an RTOS image

  bootfile	- Name of the image to load with TFTP

  autoload	- if set to "no" (any string beginning with 'n'),
		  "bootp" will just load perform a lookup of the
		  configuration from the BOOTP server, but not try to
		  load any image using TFTP

  autostart	- if set to "yes", an image loaded using the "bootp",
		  "rarpboot", "tftpboot" or "diskboot" commands will
		  be automatically started (by internally calling
		  "bootm")

  initrd_high	- restrict positioning of initrd images:
		  If this variable is not set, initrd images will be
		  copied to the highest possible address in RAM; this
		  is usually what you want since it allows for
		  maximum initrd size. If for some reason you want to
		  make sure that the initrd image is loaded below the
		  CFG_BOOTMAPSZ limit, you can set this environment
		  variable to a value of "no" or "off" or "0".
		  Alternatively, you can set it to a maximum upper
		  address to use (PPCBoot will still check that it
		  does not overwrite the PCBoot stack and data).

		  For instance, when you have a system with 16 MB
		  RAM, and want to reseve 4 MB from use by Linux,
		  you can do this by adding "mem=12M" to the value of
		  the "bootargs" variable. However, now you must make
		  sure, that the initrd image is placed in the first
		  12 MB as well - this can be done with

		  setenv initrd_high 00c00000

  ipaddr	- IP address; needed for tftpboot command

  loadaddr	- Default load address for commands like "bootp",
		  "rarpboot", "tftpboot" or "diskboot"

  loads_echo	- see CONFIG_LOADS_ECHO

  serverip	- TFTP server IP address; needed for tftpboot command

  bootretry	- see CONFIG_BOOT_RETRY_TIME

  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR

  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR


The following environment variables may be used and automatically
updated by the network boot commands ("bootp" and "rarpboot"),
depending the information provided by your boot server:

  bootfile	- see above
  dnsip		- IP address of your Domain Name Server
  gatewayip	- IP address of the Gateway (Router) to use
  hostname	- Target hostname
  ipaddr	- see above
  netmask	- Subnet Mask
  rootpath	- Pathname of the root filesystem on the NFS server
  serverip	- see above


There are two special Environment Variables:

  serial#	- contains hardware identification information such
		  as type string and/or serial number
  ethaddr	- Ethernet address

These variables can be set only once (usually during manufacturing of
the board). PPCBoot refuses to delete or overwrite these variables
once they have been set once.


Please note that changes to some configuration parameters may take
only effect after the next boot (yes, that's just like Windoze :-).



Image Formats:
==============

The "boot" commands of this monitor operate on "image" files which
can be basicly anything, preceeded by a special header; see the
definitions in include/image.h for details; basicly, the header
defines the following image properties:

* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
  LynxOS, pSOS, QNX; Currently supported: Linux).
* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
  IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
  Currently supported: PowerPC).
* Compression Type (Provisions for uncompressed, gzip, bzip2;
  Currently supported: uncompressed, gzip).
* Load Address
* Entry Point
* Image Name
* Image Timestamp

The header is marked by a special Magic Number, and both the header
and the data portions of the image are secured against corruption by
CRC32 checksums.


Linux Support:
==============

Although PPCBoot should support any OS or standalone application
easily, Linux has always been in the focus during the design of
PPCBoot.

PPCBoot includes many features that so far have been part of some
special "boot loader" code within the Linux kernel. Also, any
"initrd" images to be used are no longer part of one big Linux image;
instead, kernel and "initrd" are separate images. This implementation
serves serveral purposes:

- the same features can be used for other OS or standalone
  applications (for instance: using compressed images to reduce the
  Flash memory footprint)

- it becomes much easier to port new Linux kernel versions because
  lots of low-level, hardware dependend stuff are done by PPCBoot

- the same Linux kernel image can now be used with different "initrd"
  images; of course this also means that different kernel images can
  be run with the same "initrd". This makes testing easier (you don't
  have to build a new "zImage.initrd" Linux image when you just
  change a file in your "initrd"). Also, a field-upgrade of the
  software is easier now.


Linux HOWTO:
============

Porting Linux to PPCBoot based systems:
---------------------------------------

PPCBoot cannot save you from doing all the necessary modifications to
configure the Linux device drivers for use with your target hardware
(no, we don't intend to provide a full virtual machine interface to
Linux :-).

But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).

Just make sure your machine specific header file (for instance
include/asm-ppc/tqm8xx.h) includes the same definition of the Board
Information structure as we define in include/ppcboot.h, and make
sure that your definition of IMAP_ADDR uses the same value as your
PPCBoot configuration in CFG_IMMR.


Configuring the Linux kernel:
-----------------------------

No specific requirements for PPCBoot. Make sure you have some root
device (initial ramdisk, NFS) for your target system.


Building a Linux Image:
-----------------------

No specific requirements for PPCBoot. There is no need to add a
"ramdisk.image.gz" file when building the kernel, even when you
intend to run it with initial ramdisk.

Example:

	make TQM850L_config
	make oldconfig
	make dep
	make zImage

However, we don't use the 'zImage' (= 'arch/ppc/mbxboot/zvmlinux') we
build this way. The 'zImage' includes the old boot loader code which
we don't ned any more. Instead, we use the raw (compressed) Linux
kernel image in 'arch/ppc/coffboot/vmlinux.gz'.

There is a special tool (in 'tools/mkimage') to encapsulate this
image with header information, CRC32 checksum etc. for use with
PPCBoot:

In the first form (with "-l" option) mkimage  lists  the  information
contained  in  the header of an existing PPCBoot image; this includes
checksum verification:

	tools/mkimage -l image
	  -l ==> list image header information

The second form (with "-d" option) is used to build a PPCBoot image
from a "data file" which is used as image payload:

	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
		      -n name -d data_file image
	  -A ==> set architecture to 'arch'
	  -O ==> set operating system to 'os'
	  -T ==> set image type to 'type'
	  -C ==> set compression type 'comp'
	  -a ==> set load address to 'addr' (hex)
	  -e ==> set entry point to 'ep' (hex)
	  -n ==> set image name to 'name'
	  -d ==> use image data from 'datafile'

Right now, all Linux kernels use the same load address	(0x00000000),
but the entry point address depends on the kernel version:

- 2.2.x kernels have the entry point at 0x0000000C,
- 2.3.x and 2.4.x kernels have the entry point at 0x00000000.

So a typical call to build a PPCBoot image would read:

	-> tools/mkimage -n '2.2.13 for initrd on TQM850L' \
	> -A ppc -O linux -T kernel -C gzip -a 00000000 -e 0000000C \
	> -d /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux.gz \
	> examples/image-2.2.13-initrd
	Image Name:   2.2.13 for initrd on TQM850L
	Created:      Wed Jul 19 02:34:59 2000
	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
	Load Address: 0x00000000
	Entry Point:  0x0000000c

To verify the contents of the image (or check for corruption):

	-> tools/mkimage -l examples/image-2.2.13-initrd
	Image Name:   2.2.13 for initrd on TQM850L
	Created:      Wed Jul 19 02:34:59 2000
	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
	Load Address: 0x00000000
	Entry Point:  0x0000000c

NOTE: for embedded systems where boot time is critical you can trade
speed for memory and install an UNCOMPRESSED image instead: this
needs more space in Flash, but boots much faster since it does not
need to be uncompressed:

	-> gunzip /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux.gz
	-> tools/mkimage -n '2.2.13 for initrd on TQM850L' \
	> -A ppc -O linux -T kernel -C none -a 00000000 -e 0000000C \
	> -d /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux \
	> examples/image-2.2.13-initrd-uncompressed
	Image Name:   2.2.13 for initrd on TQM850L
	Created:      Wed Jul 19 02:34:59 2000
	Image Type:   PowerPC Linux Kernel Image (uncompressed)
	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
	Load Address: 0x00000000
	Entry Point:  0x0000000c


Similar you can build PPCBoot images from a 'ramdisk.image.gz' file
when your kernel is intended to use an initial ramdisk:

	-> tools/mkimage -n 'Simple Ramdisk Image' \
	> -A ppc -O linux -T ramdisk -C gzip \
	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
	Image Name:   Simple Ramdisk Image
	Created:      Wed Jan 12 14:01:50 2000
	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
	Load Address: 0x00000000
	Entry Point:  0x00000000


Installing a Linux Image:
-------------------------

To downloading a PPCBoot image over the serial (console) interface,
you must convert the image to S-Record format:

	objcopy -I binary -O srec examples/image examples/image.srec

The 'objcopy' does not understand the information in the PPCBoot
image header, so the resulting S-Record file will be relative to
address 0x00000000. To load it to a given address, you need to
specify the target address as 'offset' parameter with the 'loads'
command.

Example: install the image to address 0x40100000 (which on the
TQM8xxL is in the first Flash bank):

	=> erase 40100000 401FFFFF

	.......... done
	Erased 8 sectors

	=> loads 40100000
	## Ready for S-Record download ...
	~>examples/image.srec
	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
	...
	15989 15990 15991 15992
	[file transfer complete]
	[connected]
	## Start Addr = 0x00000000


You can check the success of the download using the 'iminfo' command;
this includes a checksum verification so you  can  be  sure  no	 data
corruption happened:

	=> imi 40100000

	## Checking Image at 40100000 ...
	   Image Name:	 2.2.13 for initrd on TQM850L
	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
	   Data Size:	 335725 Bytes = 327 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 0000000c
	   Verifying Checksum ... OK



Boot Linux:
-----------

The "bootm" command is used to boot an application that is stored in
memory (RAM or Flash). In case of a Linux kernel image, the contents
of the "bootargs" environment variable is passed to the kernel as
parameters. You can check and modify this variable using the
"printenv" and "setenv" commands:


	=> printenv bootargs
	bootargs=root=/dev/ram

	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2

	=> printenv bootargs
	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2

	=> bootm 40020000
	## Booting Linux kernel at 40020000 ...
	   Image Name:	 2.2.13 for NFS on TQM850L
	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
	   Data Size:	 381681 Bytes = 372 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 0000000c
	   Verifying Checksum ... OK
	   Uncompressing Kernel Image ... OK
	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
	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
	time_init: decrementer frequency = 187500000/60
	Calibrating delay loop... 49.77 BogoMIPS
	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
	...

If you want to boot a Linux kernel with initial ram disk, you pass
the memory addreses of both the kernel and the initrd image (PPBCOOT
format!) to the "bootm" command:

	=> imi 40100000 40200000

	## Checking Image at 40100000 ...
	   Image Name:	 2.2.13 for initrd on TQM850L
	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
	   Data Size:	 335725 Bytes = 327 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 0000000c
	   Verifying Checksum ... OK

	## Checking Image at 40200000 ...
	   Image Name:	 Simple Ramdisk Image
	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
	   Data Size:	 566530 Bytes = 553 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 00000000
	   Verifying Checksum ... OK

	=> bootm 40100000 40200000
	## Booting Linux kernel at 40100000 ...
	   Image Name:	 2.2.13 for initrd on TQM850L
	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
	   Data Size:	 335725 Bytes = 327 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 0000000c
	   Verifying Checksum ... OK
	   Uncompressing Kernel Image ... OK
	## Loading RAMDisk Image at 40200000 ...
	   Image Name:	 Simple Ramdisk Image
	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
	   Data Size:	 566530 Bytes = 553 kB = 0 MB
	   Load Address: 00000000
	   Entry Point:	 00000000
	   Verifying Checksum ... OK
	   Loading Ramdisk ... OK
	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
	Boot arguments: root=/dev/ram
	time_init: decrementer frequency = 187500000/60
	Calibrating delay loop... 49.77 BogoMIPS
	...
	RAMDISK: Compressed image found at block 0
	VFS: Mounted root (ext2 filesystem).

	bash#


Standalone HOWTO:
=================

One of the features of PPCBoot is that you can dynamically load and
run "standalone" applications, which can use some resources of
PPCBoot like console I/O functions or interrupt services.

Two simple examples are included with the sources:

"Hello World" Demo:
-------------------

'examples/hello_world.c' contains a small "Hello World" Demo
application; it is automatically compiled when you build PPCBoot.
It's configured to run at address 0x00040004, so you can play with it
like that:

	=> loads
	## Ready for S-Record download ...
	~>examples/hello_world.srec
	1 2 3 4 5 6 7 8 9 10 11 ...
	[file transfer complete]
	[connected]
	## Start Addr = 0x00040004

	=> go 40004 Hello World! This is a test.
	## Starting application at 0x00040004 ...
	Hello World
	argc = 7
	argv[0] = "40004"
	argv[1] = "Hello"
	argv[2] = "World!"
	argv[3] = "This"
	argv[4] = "is"
	argv[5] = "a"
	argv[6] = "test."
	argv[7] = "<NULL>"
	Hit any key to exit ...

	## Application terminated, rc = 0x0

Another example, which demonstrates how to register a CPM interrupt
handler with the PPCBoot code, can be found in 'examples/timer.c'.
Here, a CPM timer is set up to generate an interrupt every second.
The interrupt service routine is trivial, just printing a '.'
character, but this is just a demo program. The application can be
controlled by the following keys:

	? - print current values og the CPM Timer registers
	b - enable interrupts and start timer
	e - stop timer and disable interrupts
	q - quit application

	=> loads
	## Ready for S-Record download ...
	~>examples/timer.srec
	1 2 3 4 5 6 7 8 9 10 11 ...
	[file transfer complete]
	[connected]
	## Start Addr = 0x00040004

	=> go 40004
	## Starting application at 0x00040004 ...
	TIMERS=0xfff00980
	Using timer 1
	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0

Hit 'b':
	[q, b, e, ?] Set interval 1000000 us
	Enabling timer
Hit '?':
	[q, b, e, ?] ........
	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
Hit '?':
	[q, b, e, ?] .
	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
Hit '?':
	[q, b, e, ?] .
	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
Hit '?':
	[q, b, e, ?] .
	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
Hit 'e':
	[q, b, e, ?] ...Stopping timer
Hit 'q':
	[q, b, e, ?] ## Application terminated, rc = 0x0


NetBSD Notes:
=============

Starting at version 0.9.2, PPCBoot supports NetBSD both as host
(build PPCBoot) and target system (boots NetBSD/mpc8xx).

Building requires a cross environment; it is known to work on
NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
need gmake since the Makefiles are not compatible with BSD make).
Note that the cross-powerpc package does not install include files;
attempting to build PPCBoot will fail because <machine/ansi.h> is
missing.  This file has to be installed and patched manually:

	# cd /usr/pkg/cross/powerpc-netbsd/include
	# mkdir powerpc
	# ln -s powerpc machine
	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST

Native builds *don't* work due to incompatibilities between native
and PPCBoot include files.

Booting assumes that (the first part of) the image booted is a
stage-2 loader which in turn loads and then invokes the kernel
proper. Loader sources will eventually appear in the NetBSD source
tree (probably in sys/arc/mpc8xx/stand/ppcboot_stage2/); in the
meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
details.


Implementation Internals:
=========================

The following is not intended to be a complete description of every
implementation detail. However, it should help to understand the
inner workings of PPCBoot and make it easier to port it to custom
hardware.


Memory Management:
------------------

PPCBoot runs in system state and uses physical addresses, i.e. the
MMU is not used either for address mapping nor for memory protection.

The available memory is mapped to fixed addresses usuing the memory
controller. In this process, a contiguous block is formed for each
memory type (Flash, SDRAM, SRAM), even when it consists out of
several physical memory banks.

PPCBoot is installed in the first 128 kB of the first Flash bank (on
TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
booting and sizing and initializing DRAM, the code relocates itself
to the upper end of DRAM. Immediately below the PPCBoot code some
memory is reserved for use by malloc() [see CFG_MALLOC_LEN
configuration setting]. Below that, a structure with global Board
Info data is placed, followed by the stack (growing downward).

Additionally, some exception handler code is copied to the low 8 kB
of DRAM (0x00000000 ... 0x00001FFF).

So a typical memory configuration with 16 MB of DRAM could look like
this:

	0x0000 0000	Exception Vector code
	      :
	0x0000 1FFF
	0x0000 2000	Free for Application Use
	      :
	      :

	      :
	      :
	0x00FB FF20	Monitor Stack (Growing downward)
	0x00FB FFAC	Board Info Data
	0x00FC 0000	Malloc Arena
	      :
	0x00FD FFFF
	0x00FE 0000	RAM Copy of Monitor Code
	0x00FF FFFF	[End of RAM]


System Initialization:
----------------------

In the reset configuration, PPCBoot starts at address 0x00000100.
Because of the reset configuration for CS0# this is a mirror of the
onboard Flash memory. To be able to re-map memory PPCBoot then jumps
to it's link address. To be able to implement the initialization code
in C, a (small!) initial stack is set up in the internal Dual Ported
RAM of the MPC8xx. After that, PPCBoot initialises the CPU core, the
caches and the SIU.

Next, all (potentially) available memory banks are mapped using a
prelimonary mapping, which puts them on 512 MB boundaries (multiples
of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash on
0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
programmed for SDRAM access. Using the temporary configuration, a
simple memory test is run that determines the size of the SDRAM
banks.

When there is more than one SDRAM bank, and the banks are of
different size, the larger is mapped first. For equal size, the first
bank (CS2#) is mapped first. The first mapping is always for address
0x00000000, with any additional banks following immediately to create
contiguous memory starting from 0.

Then, the monitor installs itself at the upper end of the SDRAM area
and allocates memory for use by malloc() and for the global Board
Info data; also, the exception vector code is copied to the low RAM
pages, and the final stack is set up.

Only after this relocation you have a "normal" C environment; until
that you are restricted in several ways, mostly because you are
running from ROM, and because the code will have to be relocated to a
new address in RAM.
