# SPDX-License-Identifier: GPL-2.0+

#

# (C) Copyright 2000 - 2013

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

Summary:

========

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

Embedded boards based on PowerPC, ARM, MIPS and several other

processors, which can be installed in a boot ROM and used to

initialize and test the hardware or to download and run application

code.

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

the source code originate in the Linux source tree, we have some

header files in common, and special provision has been made to

support booting of Linux images.

Some attention has been paid to make this software easily

configurable and extendable. For instance, all monitor commands are

implemented with the same call interface, so that it's very easy to

add new commands. Also, instead of permanently adding rarely used

code (for instance hardware test utilities) to the monitor, you can

load and run it dynamically.

Status:

=======

In general, all boards for which a configuration option exists in the

Makefile have been tested to some extent and can be considered

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

In case of problems see the CHANGELOG file to find out who contributed

the specific port. In addition, there are various MAINTAINERS files

scattered throughout the U-Boot source identifying the people or

companies responsible for various boards and subsystems.

Note: As of August, 2010, there is no longer a CHANGELOG file in the

actual U-Boot source tree; however, it can be created dynamically

from the Git log using:

make CHANGELOG

Where to get help:

==================

In case you have questions about, problems with or contributions for

U-Boot, you should send a message to the U-Boot mailing list at

<u-boot@lists.denx.de>. There is also an archive of previous traffic

on the mailing list - please search the archive before asking FAQ's.

Please see https://lists.denx.de/pipermail/u-boot and

https://marc.info/?l=u-boot

Where to get source code:

=========================

The U-Boot source code is maintained in the Git repository at

https://source.denx.de/u-boot/u-boot.git ; you can browse it online at

https://source.denx.de/u-boot/u-boot

The "Tags" links on this page allow you to download tarballs of

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

available from the DENX file server through HTTPS or FTP.

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

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

Where we come from:

===================

- start from 8xxrom sources

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

- clean up code

- make it easier to add custom boards

- make it possible to add other [PowerPC] CPUs

- extend functions, especially:

* Provide extended interface to Linux boot loader

* S-Record download

* network boot

* ATA disk / SCSI ... boot

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

- add other CPU families (starting with ARM)

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

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

Names and Spelling:

===================

The "official" name of this project is "Das U-Boot". The spelling

"U-Boot" shall be used in all written text (documentation, comments

in source files etc.). Example:

This is the README file for the U-Boot project.

File names etc. shall be based on the string "u-boot". Examples:

include/asm-ppc/u-boot.h

#include <asm/u-boot.h>

Variable names, preprocessor constants etc. shall be either based on

the string "u_boot" or on "U_BOOT". Example:

U_BOOT_VERSION u_boot_logo

IH_OS_U_BOOT u_boot_hush_start

Versioning:

===========

Starting with the release in October 2008, the names of the releases

were changed from numerical release numbers without deeper meaning

into a time stamp based numbering. Regular releases are identified by

names consisting of the calendar year and month of the release date.

Additional fields (if present) indicate release candidates or bug fix

releases in "stable" maintenance trees.

Examples:

U-Boot v2009.11 - Release November 2009

U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree

U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release

Directory Hierarchy:

====================

/arch Architecture specific files

/arc Files generic to ARC architecture

/arm Files generic to ARM architecture

/m68k Files generic to m68k architecture

/microblaze Files generic to microblaze architecture

/mips Files generic to MIPS architecture

/nds32 Files generic to NDS32 architecture

/nios2 Files generic to Altera NIOS2 architecture

/powerpc Files generic to PowerPC architecture

/riscv Files generic to RISC-V architecture

/sandbox Files generic to HW-independent "sandbox"

/sh Files generic to SH architecture

/x86 Files generic to x86 architecture

/xtensa Files generic to Xtensa architecture

/api Machine/arch independent API for external apps

/board Board dependent files

/cmd U-Boot commands functions

/common Misc architecture independent functions

/configs Board default configuration files

/disk Code for disk drive partition handling

/doc Documentation (don't expect too much)

/drivers Commonly used device drivers

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

/env Environment files

/examples Example code for standalone applications, etc.

/fs Filesystem code (cramfs, ext2, jffs2, etc.)

/include Header Files

/lib Library routines generic to all architectures

/Licenses Various license files

/net Networking code

/post Power On Self Test

/scripts Various build scripts and Makefiles

/test Various unit test files

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

Software Configuration:

=======================

Configuration is usually done using C preprocessor defines; the

rationale behind that is to avoid dead code whenever possible.

There are two classes of configuration variables:

* Configuration _OPTIONS_:

These are selectable by the user and have names beginning with

"CONFIG_".

* Configuration _SETTINGS_:

These depend on the hardware etc. and should not be meddled with if

you don't know what you're doing; they have names beginning with

"CONFIG_SYS_".

Previously, all configuration was done by hand, which involved creating

symbolic links and editing configuration files manually. More recently,

U-Boot has added the Kbuild infrastructure used by the Linux kernel,

allowing you to use the "make menuconfig" command to configure your

build.

Selection of Processor Architecture and Board Type:

---------------------------------------------------

For all supported boards there are ready-to-use default

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

Example: For a TQM823L module type:

cd u-boot

make TQM823L_defconfig

Note: If you're looking for the default configuration file for a board

you're sure used to be there but is now missing, check the file

doc/README.scrapyard for a list of no longer supported boards.

Sandbox Environment:

--------------------

U-Boot can be built natively to run on a Linux host using the 'sandbox'

board. This allows feature development which is not board- or architecture-

specific to be undertaken on a native platform. The sandbox is also used to

run some of U-Boot's tests.

See doc/arch/sandbox.rst for more details.

Board Initialisation Flow:

--------------------------

This is the intended start-up flow for boards. This should apply for both

SPL and U-Boot proper (i.e. they both follow the same rules).

Note: "SPL" stands for "Secondary Program Loader," which is explained in

more detail later in this file.

At present, SPL mostly uses a separate code path, but the function names

and roles of each function are the same. Some boards or architectures

may not conform to this. At least most ARM boards which use

CONFIG_SPL_FRAMEWORK conform to this.

Execution typically starts with an architecture-specific (and possibly

CPU-specific) start.S file, such as:

- arch/arm/cpu/armv7/start.S

- arch/powerpc/cpu/mpc83xx/start.S

- arch/mips/cpu/start.S

and so on. From there, three functions are called; the purpose and

limitations of each of these functions are described below.

lowlevel_init():

- purpose: essential init to permit execution to reach board_init_f()

- no global_data or BSS

- there is no stack (ARMv7 may have one but it will soon be removed)

- must not set up SDRAM or use console

- must only do the bare minimum to allow execution to continue to

board_init_f()

- this is almost never needed

- return normally from this function

board_init_f():

- purpose: set up the machine ready for running board_init_r():

i.e. SDRAM and serial UART

- global_data is available

- stack is in SRAM

- BSS is not available, so you cannot use global/static variables,

only stack variables and global_data

Non-SPL-specific notes:

- dram_init() is called to set up DRAM. If already done in SPL this

can do nothing

SPL-specific notes:

- you can override the entire board_init_f() function with your own

version as needed.

- preloader_console_init() can be called here in extremis

- should set up SDRAM, and anything needed to make the UART work

- there is no need to clear BSS, it will be done by crt0.S

- for specific scenarios on certain architectures an early BSS *can*

be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing

of BSS prior to entering board_init_f()) but doing so is discouraged.

Instead it is strongly recommended to architect any code changes

or additions such to not depend on the availability of BSS during

board_init_f() as indicated in other sections of this README to

maintain compatibility and consistency across the entire code base.

- must return normally from this function (don't call board_init_r()

directly)

Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at

this point the stack and global_data are relocated to below

CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of

memory.

board_init_r():

- purpose: main execution, common code

- global_data is available

- SDRAM is available

- BSS is available, all static/global variables can be used

- execution eventually continues to main_loop()

Non-SPL-specific notes:

- U-Boot is relocated to the top of memory and is now running from

there.

SPL-specific notes:

- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and

CONFIG_SPL_STACK_R_ADDR points into SDRAM

- preloader_console_init() can be called here - typically this is

done by selecting CONFIG_SPL_BOARD_INIT and then supplying a

spl_board_init() function containing this call

- loads U-Boot or (in falcon mode) Linux

Configuration Options:

----------------------

Configuration depends on the combination of board and CPU type; all

such information is kept in a configuration file

"include/configs/<board_name>.h".

Example: For a TQM823L module, all configuration settings are in

"include/configs/TQM823L.h".

Many of the options are named exactly as the corresponding Linux

kernel configuration options. The intention is to make it easier to

build a config tool - later.

- ARM Platform Bus Type(CCI):

CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which

provides full cache coherency between two clusters of multi-core

CPUs and I/O coherency for devices and I/O masters

CONFIG_SYS_FSL_HAS_CCI400

Defined For SoC that has cache coherent interconnect

CCN-400

CONFIG_SYS_FSL_HAS_CCN504

Defined for SoC that has cache coherent interconnect CCN-504

The following options need to be configured:

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

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

- 85xx CPU Options:

CONFIG_SYS_PPC64

Specifies that the core is a 64-bit PowerPC implementation (implements

the "64" category of the Power ISA). This is necessary for ePAPR

compliance, among other possible reasons.

CONFIG_SYS_FSL_TBCLK_DIV

Defines the core time base clock divider ratio compared to the

system clock. On most PQ3 devices this is 8, on newer QorIQ

devices it can be 16 or 32. The ratio varies from SoC to Soc.

CONFIG_SYS_FSL_PCIE_COMPAT

Defines the string to utilize when trying to match PCIe device

tree nodes for the given platform.

CONFIG_SYS_FSL_ERRATUM_A004510

Enables a workaround for erratum A004510. If set,

then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and

CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.

CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV

CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)

Defines one or two SoC revisions (low 8 bits of SVR)

for which the A004510 workaround should be applied.

The rest of SVR is either not relevant to the decision

of whether the erratum is present (e.g. p2040 versus

p2041) or is implied by the build target, which controls

whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.

See Freescale App Note 4493 for more information about

this erratum.

CONFIG_A003399_NOR_WORKAROUND

Enables a workaround for IFC erratum A003399. It is only

required during NOR boot.

CONFIG_A008044_WORKAROUND

Enables a workaround for T1040/T1042 erratum A008044. It is only

required during NAND boot and valid for Rev 1.0 SoC revision

CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY

This is the value to write into CCSR offset 0x18600

according to the A004510 workaround.

CONFIG_SYS_FSL_DSP_DDR_ADDR

This value denotes start offset of DDR memory which is

connected exclusively to the DSP cores.

CONFIG_SYS_FSL_DSP_M2_RAM_ADDR

This value denotes start offset of M2 memory

which is directly connected to the DSP core.

CONFIG_SYS_FSL_DSP_M3_RAM_ADDR

This value denotes start offset of M3 memory which is directly

connected to the DSP core.

CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT

This value denotes start offset of DSP CCSR space.

CONFIG_SYS_FSL_SINGLE_SOURCE_CLK

Single Source Clock is clocking mode present in some of FSL SoC's.

In this mode, a single differential clock is used to supply

clocks to the sysclock, ddrclock and usbclock.

CONFIG_SYS_CPC_REINIT_F

This CONFIG is defined when the CPC is configured as SRAM at the

time of U-Boot entry and is required to be re-initialized.

CONFIG_DEEP_SLEEP

Indicates this SoC supports deep sleep feature. If deep sleep is

supported, core will start to execute uboot when wakes up.

- Generic CPU options:

CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN

Defines the endianess of the CPU. Implementation of those

values is arch specific.

CONFIG_SYS_FSL_DDR

Freescale DDR driver in use. This type of DDR controller is

found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core

SoCs.

CONFIG_SYS_FSL_DDR_ADDR

Freescale DDR memory-mapped register base.

CONFIG_SYS_FSL_DDR_EMU

Specify emulator support for DDR. Some DDR features such as

deskew training are not available.

CONFIG_SYS_FSL_DDRC_GEN1

Freescale DDR1 controller.

CONFIG_SYS_FSL_DDRC_GEN2

Freescale DDR2 controller.

CONFIG_SYS_FSL_DDRC_GEN3

Freescale DDR3 controller.

CONFIG_SYS_FSL_DDRC_GEN4

Freescale DDR4 controller.

CONFIG_SYS_FSL_DDRC_ARM_GEN3

Freescale DDR3 controller for ARM-based SoCs.

CONFIG_SYS_FSL_DDR1

Board config to use DDR1. It can be enabled for SoCs with

Freescale DDR1 or DDR2 controllers, depending on the board

implemetation.

CONFIG_SYS_FSL_DDR2

Board config to use DDR2. It can be enabled for SoCs with

Freescale DDR2 or DDR3 controllers, depending on the board

implementation.

CONFIG_SYS_FSL_DDR3

Board config to use DDR3. It can be enabled for SoCs with

Freescale DDR3 or DDR3L controllers.

CONFIG_SYS_FSL_DDR3L

Board config to use DDR3L. It can be enabled for SoCs with

DDR3L controllers.

CONFIG_SYS_FSL_DDR4

Board config to use DDR4. It can be enabled for SoCs with

DDR4 controllers.

CONFIG_SYS_FSL_IFC_BE

Defines the IFC controller register space as Big Endian

CONFIG_SYS_FSL_IFC_LE

Defines the IFC controller register space as Little Endian

CONFIG_SYS_FSL_IFC_CLK_DIV

Defines divider of platform clock(clock input to IFC controller).

CONFIG_SYS_FSL_LBC_CLK_DIV

Defines divider of platform clock(clock input to eLBC controller).

CONFIG_SYS_FSL_PBL_PBI

It enables addition of RCW (Power on reset configuration) in built image.

Please refer doc/README.pblimage for more details

CONFIG_SYS_FSL_PBL_RCW

It adds PBI(pre-boot instructions) commands in u-boot build image.

PBI commands can be used to configure SoC before it starts the execution.

Please refer doc/README.pblimage for more details

CONFIG_SYS_FSL_DDR_BE

Defines the DDR controller register space as Big Endian

CONFIG_SYS_FSL_DDR_LE

Defines the DDR controller register space as Little Endian

CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY

Physical address from the view of DDR controllers. It is the

same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But

it could be different for ARM SoCs.

CONFIG_SYS_FSL_DDR_INTLV_256B

DDR controller interleaving on 256-byte. This is a special

interleaving mode, handled by Dickens for Freescale layerscape

SoCs with ARM core.

CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS

Number of controllers used as main memory.

CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS

Number of controllers used for other than main memory.

CONFIG_SYS_FSL_HAS_DP_DDR

Defines the SoC has DP-DDR used for DPAA.

CONFIG_SYS_FSL_SEC_BE

Defines the SEC controller register space as Big Endian

CONFIG_SYS_FSL_SEC_LE

Defines the SEC controller register space as Little Endian

- MIPS CPU options:

CONFIG_SYS_INIT_SP_OFFSET

Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack

pointer. This is needed for the temporary stack before

relocation.

CONFIG_XWAY_SWAP_BYTES

Enable compilation of tools/xway-swap-bytes needed for Lantiq

XWAY SoCs for booting from NOR flash. The U-Boot image needs to

be swapped if a flash programmer is used.

- ARM options:

CONFIG_SYS_EXCEPTION_VECTORS_HIGH

Select high exception vectors of the ARM core, e.g., do not

clear the V bit of the c1 register of CP15.

COUNTER_FREQUENCY

Generic timer clock source frequency.

COUNTER_FREQUENCY_REAL

Generic timer clock source frequency if the real clock is

different from COUNTER_FREQUENCY, and can only be determined

at run time.

- Tegra SoC options:

CONFIG_TEGRA_SUPPORT_NON_SECURE

Support executing U-Boot in non-secure (NS) mode. Certain

impossible actions will be skipped if the CPU is in NS mode,

such as ARM architectural timer initialization.

- Linux Kernel Interface:

CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]

When transferring memsize parameter to Linux, some versions

expect it to be in bytes, others in MB.

Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.

CONFIG_OF_LIBFDT

New kernel versions are expecting firmware settings to be

passed using flattened device trees (based on open firmware

concepts).

CONFIG_OF_LIBFDT

* New libfdt-based support

* Adds the "fdt" command

* The bootm command automatically updates the fdt

OF_TBCLK - The timebase frequency.

boards with QUICC Engines require OF_QE to set UCC MAC

addresses

CONFIG_OF_BOARD_SETUP

Board code has addition modification that it wants to make

to the flat device tree before handing it off to the kernel

CONFIG_OF_SYSTEM_SETUP

Other code has addition modification that it wants to make

to the flat device tree before handing it off to the kernel.

This causes ft_system_setup() to be called before booting

the kernel.

CONFIG_OF_IDE_FIXUP

U-Boot can detect if an IDE device is present or not.

If not, and this new config option is activated, U-Boot

removes the ATA node from the DTS before booting Linux,

so the Linux IDE driver does not probe the device and

crash. This is needed for buggy hardware (uc101) where

no pull down resistor is connected to the signal IDE5V_DD7.

CONFIG_MACH_TYPE [relevant for ARM only][mandatory]

This setting is mandatory for all boards that have only one

machine type and must be used to specify the machine type

number as it appears in the ARM machine registry

(see https://www.arm.linux.org.uk/developer/machines/).

Only boards that have multiple machine types supported

in a single configuration file and the machine type is

runtime discoverable, do not have to use this setting.

- vxWorks boot parameters:

bootvx constructs a valid bootline using the following

environments variables: bootdev, bootfile, ipaddr, netmask,

serverip, gatewayip, hostname, othbootargs.

It loads the vxWorks image pointed bootfile.

Note: If a "bootargs" environment is defined, it will override

the defaults discussed just above.

- Cache Configuration:

CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot

- Cache Configuration for ARM:

CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache

controller

CONFIG_SYS_PL310_BASE - Physical base address of PL310

controller register space

- Serial Ports:

CONFIG_PL010_SERIAL

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

CONFIG_PL011_SERIAL

Define this if you want support for Amba PrimeCell PL011 UARTs.

CONFIG_PL011_CLOCK

If you have Amba PrimeCell PL011 UARTs, set this variable to

the clock speed of the UARTs.

CONFIG_PL01x_PORTS

If you have Amba PrimeCell PL010 or PL011 UARTs on your board,

define this to a list of base addresses for each (supported)

port. See e.g. include/configs/versatile.h

CONFIG_SERIAL_HW_FLOW_CONTROL

Define this variable to enable hw flow control in serial driver.

Current user of this option is drivers/serial/nsl16550.c driver

- Autoboot Command:

CONFIG_BOOTCOMMAND

Only needed when CONFIG_BOOTDELAY is enabled;

define a command string that is automatically executed

when no character is read on the console interface

within "Boot Delay" after reset.

CONFIG_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.

- Serial Download Echo Mode:

CONFIG_LOADS_ECHO

If defined to 1, all characters received during a

serial download (using the "loads" command) are

echoed back. This might be needed by some terminal

emulations (like "cu"), but may as well just take

time on others. This setting #define's the initial

value of the "loads_echo" environment variable.

- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)

CONFIG_KGDB_BAUDRATE

Select one of the baudrates listed in

CONFIG_SYS_BAUDRATE_TABLE, see below.

- Removal of commands

If no commands are needed to boot, you can disable

CONFIG_CMDLINE to remove them. In this case, the command line

will not be available, and when U-Boot wants to execute the

boot command (on start-up) it will call board_run_command()

instead. This can reduce image size significantly for very

simple boot procedures.

- Regular expression support:

CONFIG_REGEX

If this variable is defined, U-Boot is linked against

the SLRE (Super Light Regular Expression) library,

which adds regex support to some commands, as for

example "env grep" and "setexpr".

- Device tree:

CONFIG_OF_CONTROL

If this variable is defined, U-Boot will use a device tree

to configure its devices, instead of relying on statically

compiled #defines in the board file. This option is

experimental and only available on a few boards. The device

tree is available in the global data as gd->fdt_blob.

U-Boot needs to get its device tree from somewhere. This can

be done using one of the three options below:

CONFIG_OF_EMBED

If this variable is defined, U-Boot will embed a device tree

binary in its image. This device tree file should be in the

board directory and called <soc>-<board>.dts. The binary file

is then picked up in board_init_f() and made available through

the global data structure as gd->fdt_blob.

CONFIG_OF_SEPARATE

If this variable is defined, U-Boot will build a device tree

binary. It will be called u-boot.dtb. Architecture-specific

code will locate it at run-time. Generally this works by:

cat u-boot.bin u-boot.dtb >image.bin

and in fact, U-Boot does this for you, creating a file called

u-boot-dtb.bin which is useful in the common case. You can

still use the individual files if you need something more

exotic.

CONFIG_OF_BOARD

If this variable is defined, U-Boot will use the device tree

provided by the board at runtime instead of embedding one with

the image. Only boards defining board_fdt_blob_setup() support

this option (see include/fdtdec.h file).

- Watchdog:

CONFIG_WATCHDOG

If this variable is defined, it enables watchdog

support for the SoC. There must be support in the SoC

specific code for a watchdog. For the 8xx

CPUs, the SIU Watchdog feature is enabled in the SYPCR

register. When supported for a specific SoC is

available, then no further board specific code should

be needed to use it.

CONFIG_HW_WATCHDOG

When using a watchdog circuitry external to the used

SoC, then define this variable and provide board

specific code for the "hw_watchdog_reset" function.

- Real-Time Clock:

When CONFIG_CMD_DATE is selected, the type of the RTC

has to be selected, too. Define exactly one of the

following options:

CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC

CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC

CONFIG_RTC_MC146818 - use MC146818 RTC

CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC

CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC

CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC

CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC

CONFIG_RTC_DS164x - use Dallas DS164x RTC

CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC

CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC

CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337

CONFIG_SYS_RV3029_TCR - enable trickle charger on

RV3029 RTC.

Note that if the RTC uses I2C, then the I2C interface

must also be configured. See I2C Support, below.

- GPIO Support:

CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO

The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of

chip-ngpio pairs that tell the PCA953X driver the number of

pins supported by a particular chip.

Note that if the GPIO device uses I2C, then the I2C interface

must also be configured. See I2C Support, below.

- I/O tracing:

When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O

accesses and can checksum them or write a list of them out

to memory. See the 'iotrace' command for details. This is

useful for testing device drivers since it can confirm that

the driver behaves the same way before and after a code

change. Currently this is supported on sandbox and arm. To

add support for your architecture, add '#include <iotrace.h>'

to the bottom of arch/<arch>/include/asm/io.h and test.

Example output from the 'iotrace stats' command is below.

Note that if the trace buffer is exhausted, the checksum will

still continue to operate.

iotrace is enabled

Start: 10000000 (buffer start address)

Size: 00010000 (buffer size)

Offset: 00000120 (current buffer offset)

Output: 10000120 (start + offset)

Count: 00000018 (number of trace records)

CRC32: 9526fb66 (CRC32 of all trace records)

- Timestamp Support:

When CONFIG_TIMESTAMP is selected, the timestamp

(date and time) of an image is printed by image

commands like bootm or iminfo. This option is

automatically enabled when you select CONFIG_CMD_DATE .

- Partition Labels (disklabels) Supported:

Zero or more of the following:

CONFIG_MAC_PARTITION Apple's MacOS partition table.

CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.

CONFIG_EFI_PARTITION GPT partition table, common when EFI is the

bootloader. Note 2TB partition limit; see

disk/part_efi.c

CONFIG_SCSI) you must configure support for at

least one non-MTD partition type as well.

- IDE Reset method:

CONFIG_IDE_RESET_ROUTINE - this is defined in several

board configurations files but used nowhere!

CONFIG_IDE_RESET - is this is defined, IDE Reset will

be performed by calling the function

ide_set_reset(int reset)

which has to be defined in a board specific file

- ATAPI Support:

CONFIG_ATAPI

Set this to enable ATAPI support.

- LBA48 Support

CONFIG_LBA48

Set this to enable support for disks larger than 137GB

Also look at CONFIG_SYS_64BIT_LBA.

Whithout these , LBA48 support uses 32bit variables and will 'only'

support disks up to 2.1TB.

CONFIG_SYS_64BIT_LBA:

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

Default is 32bit.

- SCSI Support:

CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and

CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *

CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the

maximum numbers of LUNs, SCSI ID's and target

devices.

The environment variable 'scsidevs' is set to the number of

SCSI devices found during the last scan.

- NETWORK Support (PCI):

CONFIG_E1000

Support for Intel 8254x/8257x gigabit chips.

CONFIG_E1000_SPI

Utility code for direct access to the SPI bus on Intel 8257x.

This does not do anything useful unless you set at least one

of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.

CONFIG_E1000_SPI_GENERIC

Allow generic access to the SPI bus on the Intel 8257x, for

example with the "sspi" command.

CONFIG_NATSEMI

Support for National dp83815 chips.

CONFIG_NS8382X

Support for National dp8382[01] gigabit chips.

- NETWORK Support (other):

CONFIG_DRIVER_AT91EMAC

Support for AT91RM9200 EMAC.

CONFIG_RMII

Define this to use reduced MII inteface

CONFIG_DRIVER_AT91EMAC_QUIET

If this defined, the driver is quiet.

The driver doen't show link status messages.

CONFIG_CALXEDA_XGMAC

Support for the Calxeda XGMAC device

CONFIG_LAN91C96

Support for SMSC's LAN91C96 chips.

CONFIG_LAN91C96_USE_32_BIT

Define this to enable 32 bit addressing

CONFIG_SMC91111

Support for SMSC's LAN91C111 chip

CONFIG_SMC91111_BASE

Define this to hold the physical address

of the device (I/O space)

CONFIG_SMC_USE_32_BIT

Define this if data bus is 32 bits

CONFIG_SMC_USE_IOFUNCS

Define this to use i/o functions instead of macros

(some hardware wont work with macros)

CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT

Define this if you have more then 3 PHYs.

CONFIG_FTGMAC100

Support for Faraday's FTGMAC100 Gigabit SoC Ethernet

CONFIG_FTGMAC100_EGIGA

Define this to use GE link update with gigabit PHY.

Define this if FTGMAC100 is connected to gigabit PHY.

If your system has 10/100 PHY only, it might not occur

wrong behavior. Because PHY usually return timeout or

useless data when polling gigabit status and gigabit

control registers. This behavior won't affect the

correctnessof 10/100 link speed update.

CONFIG_SH_ETHER

Support for Renesas on-chip Ethernet controller

CONFIG_SH_ETHER_USE_PORT

Define the number of ports to be used

CONFIG_SH_ETHER_PHY_ADDR

Define the ETH PHY's address

CONFIG_SH_ETHER_CACHE_WRITEBACK

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

- TPM Support:

CONFIG_TPM

Support TPM devices.

CONFIG_TPM_TIS_INFINEON

Support for Infineon i2c bus TPM devices. Only one device

per system is supported at this time.

CONFIG_TPM_TIS_I2C_BURST_LIMITATION

Define the burst count bytes upper limit

CONFIG_TPM_ST33ZP24

Support for STMicroelectronics TPM devices. Requires DM_TPM support.

CONFIG_TPM_ST33ZP24_I2C

Support for STMicroelectronics ST33ZP24 I2C devices.

Requires TPM_ST33ZP24 and I2C.

CONFIG_TPM_ST33ZP24_SPI

Support for STMicroelectronics ST33ZP24 SPI devices.

Requires TPM_ST33ZP24 and SPI.

CONFIG_TPM_ATMEL_TWI

Support for Atmel TWI TPM device. Requires I2C support.

CONFIG_TPM_TIS_LPC

Support for generic parallel port TPM devices. Only one device

per system is supported at this time.

CONFIG_TPM_TIS_BASE_ADDRESS

Base address where the generic TPM device is mapped

to. Contemporary x86 systems usually map it at

0xfed40000.

CONFIG_TPM

Define this to enable the TPM support library which provides

functional interfaces to some TPM commands.

Requires support for a TPM device.

CONFIG_TPM_AUTH_SESSIONS

Define this to enable authorized functions in the TPM library.

Requires CONFIG_TPM and CONFIG_SHA1.

- USB Support:

At the moment only the UHCI host controller is

supported (PIP405, MIP405); define

CONFIG_USB_UHCI to enable it.

define CONFIG_USB_KEYBOARD to enable the USB Keyboard

and define CONFIG_USB_STORAGE to enable the USB

storage devices.

Note:

Supported are USB Keyboards and USB Floppy drives

(TEAC FD-05PUB).

CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the

txfilltuning field in the EHCI controller on reset.

CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2

HW module registers.

- USB Device:

Define the below if you wish to use the USB console.