Patch merged into coreboot/master: 37d7ac8 i2c: Add software_i2c driver for I2C debugging and emulation

the following patch was just integrated into master:
commit 37d7ac8b5ba12d4618b8a91f35d444fe9572beb4
Author: Julius Werner 
Date:   Mon May 5 18:03:46 2014 -0700

i2c: Add software_i2c driver for I2C debugging and emulation

This patch adds I2C emulation in software through raw toggling of the
    SDA/SCL lines. Platforms need to provide bindings to toggle their
    respective I2C busses for this to work (e.g. by pinmuxing them as GPIOs,
    currently only enabled for Tegra).

This is mostly useful as a debugging feature, to drive unusual states on
    a bus and closely monitor the device output without the need of a bus
    analyzer. It provides a few functions to "wedge" an I2C bus by aborting
    a transaction at certain points, which can be used to test if a system
    can correctly recover from an ill-timed reboot. However, it can also
    dynamically replace the existing I2C transfer functions and drive
    some/all I2C transfers on the system, which might be useful if a driver
    for the actual I2C controller hardware is not (yet) available.

Based on original code by Doug Anderson  and
    Hung-ying Tyan  for the ChromeOS embedded
    controller project.

BRANCH=None
    BUG=chrome-os-partner:28323
    TEST=Spread tegra_software_i2c_init()/tegra_software_i2c_disable()
    through the code and see that everything still works.

Original-Change-Id: I9ee7ccbd1efb38206669a35d0c3318af16f8be63
    Original-Signed-off-by: Julius Werner 
    Original-Reviewed-on: https://chromium-review.googlesource.com/198791
    Original-Reviewed-by: Doug Anderson 
    Original-Reviewed-by: Tom Warren 
    Original-Reviewed-by: Stefan Reinauer 
    (cherry picked from commit 8f71503dbbd74c5298e90e2163b67d4efe3e89db)
    Signed-off-by: Marc Jones

Change-Id: Id6c5f75bb5baaabd62b6b1fc26c2c71d9f1ce682
    Reviewed-on: http://review.coreboot.org/7947
    Tested-by: build bot (Jenkins)
    Reviewed-by: David Hendricks

See http://review.coreboot.org/7947 for details.

-gerrit