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Jens Rottmann 3914a316c3 AMD SB800: don't switch clock from 14 to 48 MHz for smscsuperio
The power up default for the 14M_25M_48M_OSC switchable clock output ball of
the SB800 chipset is 14 MHz.  sb800/bootblock.c changes this to 48 MHz,
which is the correct value for almost all SIOs.  However, not for
'smscsuperio' (SMSC SCH311x), which needs the original 14 MHz and is not
configurable for other clock speeds.  A wrong SIO clock supply results in
funny RS232 output (wrong bit speed) and non-working PS/2.

We could switch back to 14 MHz in the mainboard's romstage.c, but then the
clock frequency would change twice.  The resulting short 48 MHz burst causes
a handful of rubbish characters on RS232 on every boot until the SIO clock
has stabilized again.

This patch skips the SB800 clock switch if the SIO Kconfig requests 14 MHz.
This does not affect any boards currently in the repository (yet).

Change-Id: Icff41fd88dc41c08f3700ab4f786852f04eff2a4
Signed-off-by: Jens Rottmann <JRottmann@LiPPERTembedded.de>
Reviewed-on: http://review.coreboot.org/2454
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martin.roth@se-eng.com>
2013-03-06 19:07:28 +01:00
3rdparty@dac1a18d18 Update 3rdparty mark to latest repository 2013-02-22 09:22:41 +01:00
documentation sconfig: rename lapic_cluster -> cpu_cluster 2013-02-14 07:07:20 +01:00
payloads libpayload: Turn on thumb interworking in libpayload. 2013-03-04 22:47:49 +01:00
src AMD SB800: don't switch clock from 14 to 48 MHz for smscsuperio 2013-03-06 19:07:28 +01:00
util GPLv2 notice: Unify all files to just use one space in »MA 02110-1301« 2013-03-01 10:16:08 +01:00
.gitignore add a few entries to .gitignore 2013-01-10 22:51:20 +01:00
.gitmodules Add 3rdparty as submodule 2012-05-01 00:08:37 +02:00
.gitreview add .gitreview 2012-11-01 23:13:39 +01:00
COPYING update license template. 2006-08-12 22:03:36 +00:00
Makefile build system: Retire REQUIRES_BLOB 2013-02-19 11:00:41 +01:00
Makefile.inc build system: Retire REQUIRES_BLOB 2013-02-19 11:00:41 +01:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00

README

-------------------------------------------------------------------------------
coreboot README
-------------------------------------------------------------------------------

coreboot is a Free Software project aimed at replacing the proprietary BIOS
(firmware) found in most computers.  coreboot performs a little bit of
hardware initialization and then executes additional boot logic, called a
payload.

With the separation of hardware initialization and later boot logic,
coreboot can scale from specialized applications that run directly
firmware, run operating systems in flash, load custom
bootloaders, or implement firmware standards, like PC BIOS services or
UEFI. This allows for systems to only include the features necessary
in the target application, reducing the amount of code and flash space
required.

coreboot was formerly known as LinuxBIOS.


Payloads
--------

After the basic initialization of the hardware has been performed, any
desired "payload" can be started by coreboot.

See http://www.coreboot.org/Payloads for a list of supported payloads.


Supported Hardware
------------------

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

 * http://www.coreboot.org/Supported_Motherboards
 * http://www.coreboot.org/Supported_Chipsets_and_Devices


Build Requirements
------------------

 * gcc / g++
 * make

Optional:

 * doxygen (for generating/viewing documentation)
 * iasl (for targets with ACPI support)
 * gdb (for better debugging facilities on some targets)
 * ncurses (for 'make menuconfig')
 * flex and bison (for regenerating parsers)


Building coreboot
-----------------

Please consult http://www.coreboot.org/Build_HOWTO for details.


Testing coreboot Without Modifying Your Hardware
------------------------------------------------

If you want to test coreboot without any risks before you really decide
to use it on your hardware, you can use the QEMU system emulator to run
coreboot virtually in QEMU.

Please see http://www.coreboot.org/QEMU for details.


Website and Mailing List
------------------------

Further details on the project, a FAQ, many HOWTOs, news, development
guidelines and more can be found on the coreboot website:

  http://www.coreboot.org

You can contact us directly on the coreboot mailing list:

  http://www.coreboot.org/Mailinglist


Copyright and License
---------------------

The copyright on coreboot is owned by quite a large number of individual
developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL).
Some files are licensed under the "GPL (version 2, or any later version)",
and some files are licensed under the "GPL, version 2". For some parts, which
were derived from other projects, other (GPL-compatible) licenses may apply.
Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.