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Vadim Bendebury 9c9c336464 Generalize revision number calculation function
Some platforms use tertiary interpretation of GPIO input state to
increase number of distinct values represented by a limited number of
GPIOs. The three states are

- external pull down (interpreted as 0)
- external pull up (1)
- not connected (2)

This has been required by Nvidia devices so far, but Exynos and
Ipq8086 platforms need this too.

This patch moves the function reading the tertiary state into the
library and exposes the necessary GPIO API functions in a new include
file. The functions are still supposed to be provided by platform
specific modules.

The function interpreting the GPIO states has been modified to allow
to interpret the state either as a true tertiary number or as a set
two bit fields.

Since linker garbage collection is not happening when building x86
targets, a new configuration option is being added to include the new
module only when needed.

BUG=chrome-os-partner:30489
TEST=verified that nyan_big still reports proper revision ID.

Change-Id: Ib55122c359629b58288c1022da83e6c63dc2264d
Original-Change-Id: I243c9f43c82bd4a41de2154bbdbd07df0a241046
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/209673
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit c79ef1c545d073eaad69e6c8c629f9656b8c2f3e)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-on: http://review.coreboot.org/8717
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2015-03-23 17:20:04 +01:00
3rdparty@2bc495fd31 3rdparty: Update submodule to get Tegra 132 binaries 2015-03-07 17:50:58 +01:00
documentation documentation: begin documenting our use of git submodules 2015-02-13 09:33:24 +01:00
payloads libpayload arm64: Allow board to define upper address limit on DMA 2015-03-23 13:11:24 +01:00
src Generalize revision number calculation function 2015-03-23 17:20:04 +01:00
util build: mips: add default compilation options 2015-03-23 15:35:12 +01:00
.gitignore .gitignore: add the doxygen directory. 2014-12-14 23:30:45 +01:00
.gitmodules nvidia/cbootimage: avoid upstream's build system 2014-10-02 10:26:58 +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: Allow running make what-jenkins-does without ccache 2015-02-17 18:48:14 +01:00
Makefile.inc imgtec/danube: Build BIMG boot images 2015-03-21 16:57:22 +01:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00
toolchain.inc console: Allow bootblock console on MIPS 2015-03-23 15:35:06 +01:00

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.