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 <dianders@chromium.org> and
Hung-ying Tyan <tyanh@chromium.org> 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 <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/198791
Original-Reviewed-by: Doug Anderson <dianders@chromium.org>
Original-Reviewed-by: Tom Warren <twarren@nvidia.com>
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 8f71503dbbd74c5298e90e2163b67d4efe3e89db)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Change-Id: Id6c5f75bb5baaabd62b6b1fc26c2c71d9f1ce682
Reviewed-on: http://review.coreboot.org/7947
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
The new API is in use in depthcharge and is based around the "i2c_transfer"
function instead of i2c_read and i2c_write. The new function takes an array of
i2c_seg structures which represent each portion of the transfer after a start
bit and before the stop bit. If there's more than one segment, they're
seperated by repeated starts.
Some wrapper functions have also been added which make certain common
operations easy. These include reading or writing a byte from a register or
reading or writing a blob of raw data. The i2c device drivers generally use
these wrappers but can call the i2c_transfer function directly if the need
something different.
The tegra i2c driver was very similar to the one in depthcharge and was simple
to convert. The Exynos 5250 and 5420 drivers were ported from depthcharge and
replace the ones in coreboot. The Exynos 5420 driver was ported from the high
speed portion of the one in coreboot and was straightforward to port back. The
low speed portion and the Exynos 5250 drivers had been transplanted from U-Boot
and were replaced with the depthcharge implementation.
BUG=None
TEST=Built and booted on nyan with and without EFS. Built and booted on, pit
and daisy.
BRANCH=None
Original-Change-Id: I1e98c3fa2560be25444ab3d0394bb214b9d56e93
Original-Signed-off-by: Gabe Black <gabeblack@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/193561
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Original-Reviewed-by: Jimmy Zhang <jimmzhang@nvidia.com>
Original-Tested-by: Jimmy Zhang <jimmzhang@nvidia.com>
Original-Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Original-Commit-Queue: Gabe Black <gabeblack@chromium.org>
Original-Tested-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 00c423fb2c06c69d580ee3ec0a3892ebf164a5fe)
This cherry-pick required additional changes to the following:
src/cpu/allwinner/a10/twi.c
src/drivers/xpowers/axp209/axp209.c
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Change-Id: I691959c66308eeeec219b1bec463b8b365a246d7
Reviewed-on: http://review.coreboot.org/7751
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Data is intended to be a byte array, so it should be described by a type which
has a fixed size equal to an 8 bit byte. Also, the data passed to write
shouldn't be modified and can be const.
Change-Id: I6466303d962998f6c37c2d4006a39c2d79a235c1
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/3721
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
The existing header was imported along with the Exynos code and left
mostly unchanged. This is the first patch in a series intended to
replace the imported u-boot I2C API with a much simpler and cleaner
interface:
- We only need to expose i2c_read() and i2c_write() in our public API.
Everything else is board/chip-dependent and should remain hidden
away.
- i2c_read and i2c_write functions will take bus number as an arg
and we'll eliminate i2c_get_bus and i2c_set_bus. Those are prone to
error and end up cluttering the code since the user needs to save
the old bus number, set the new one, do the read/write, and restore
the old value (3 added steps to do a simple transaction).
- Stop setting default values for board-specific things like SPD
and RTC bus numbers (as if we always have an SPD or RTC on I2C).
- Death to all the trivial inline wrappers. And in case there was any
doubt, we really don't care about the MPC8xx. Though if we did then
we would not pollute the public API with its idiosyncrasies.
Change-Id: I4410a3c82ed5a6b2e80e3d8c0163464a9ca7c3b0
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/3043
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
This just imports a header. We may wish to modify the i2c interface
and/or unify it with the smbus interface we currently have.
Change-Id: I314f3aef62be936456c6c3e164a3db2c473b8792
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2079
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Julius Werner