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Gabe Black f296c94522 tegra: spi: Read the command1 register to ensure the write to it completes.
To ensure that the command1 write which sets the "go" bit completes before
other reads to the device. Otherwise, there's a race condition where those
register values might still have their values from the last transfer. With
different SPI clock frequencies, that could lead to spi_delay being told there
were negative bytes still to send. Its expected delay would wrap to a negative
value, that was passed to udelay, and the system would sit there for 4 seconds
not doing anything.

BUG=None
TEST=Built and booted on nyan. Set the SPI bus frequency to a value which was
causing the 4+ second delay and verified that it no longer happened.
BRANCH=None

Original-Change-Id: I8b4090efc69f34d0413e3f63c59c1825dd151cec
Original-Signed-off-by: Gabe Black <gabeblack@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/193347
Original-Reviewed-by: Gabe Black <gabeblack@chromium.org>
Original-Commit-Queue: Gabe Black <gabeblack@chromium.org>
Original-Tested-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit d7ea9febdf2c5942f81607ee6ded786c9a8954bb)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I095bfc745eda37b8e666475ceb41684152f3709a
Reviewed-on: http://review.coreboot.org/7737
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2014-12-15 19:58:02 +01:00
3rdparty@9f68e20e5e 3rdparty: Update to latest commit in blobs repository 2014-12-01 08:50:32 +01:00
documentation mkelfimage: remove 2014-10-08 14:27:24 +02:00
payloads ARM: API to Map Physical Address to Wipe Memory above 4GB 2014-12-09 18:39:34 +01:00
src tegra: spi: Read the command1 register to ensure the write to it completes. 2014-12-15 19:58:02 +01:00
util buildgcc: Fix msys2 crossgcc build fail 2014-12-15 16:49:42 +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
COPYING
Makefile Makefile: Tone down some clang warnings, some are unproductive 2014-12-12 13:29:47 +01:00
Makefile.inc build system: fix alignment function 2014-12-03 15:50:28 +01:00
README
toolchain.inc Add UCB RISCV support for architecture, soc, and emulation mainboard.. 2014-12-01 19:06:43 +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.