According to "KeyStone Architecture Inter-IC Control Bus User Guide", fixed
additive part of frequency divisors (referred as "d" in the code and datasheet)
always equals to 6, independent of module clock prescaler.
module clock frequency
master clock frequency = ----------------------
(ICCL + 6) + (ICCH + 6)
It was not the case with original Davinci IP. Introduce new compatible property
"ti,keystone-i2c", which triggers special handling in the driver.
Without this change Keystone-based systems (having 204.8MHz input clock) choose
prescaler 29 (PSC=28). Using d=5 in this case leads to bus bitrate ~353kHz
instead of requested 400kHz. After correction, assuming d=6 bus rate is ~392kHz.
This gives ~11% transfer rate increase.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Tested-by: Hemanth Guruva Reddy <hemanth.guruva_reddy@nokia.com>
Tested-by: Lukasz Gemborowski <lukasz.gemborowski@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Having a board where the I2C bus locks up occasionally made it clear
that the bus recovery in the i2c-davinci driver will only work on
some boards, because on regular boards, this will only toggle GPIO
lines that aren't muxed to the actual pins.
The I2C controller on SoCs like da850 (and da830), Keystone 2 has the
built-in capability to bit-bang its lines by using the ICPFUNC registers
of the i2c controller.
Implement the suggested procedure by toggling SCL and checking SDA using
the ICPFUNC registers of the I2C controller when present. Allow platforms
to indicate the presence of the ICPFUNC registers with a has_pfunc platform
data flag and add optional DT property "ti,has-pfunc" to indicate
the same in DT.
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Tested-by: Michael Lawnick <michael.lawnick@nokia.com>
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Signed-off-by: Mike Looijmans <milo-software@users.sourceforge.net>
[grygorii.strashko@ti.com: combined patches from Ben Gardiner and
Mike Looijmans and reimplemented ICPFUNC bus recovery using I2C
bus recovery infrastructure]
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Filenames of devictree binding documentation seems to be arbitrary and
for me it is unneeded hazzle to find the corresponding documentation for
a specific driver.
Naming the description the same as the driver is a lot easier and makes
sense to me since the driver defines the binding it understands.
Also, remove a reference in one source to the binding documentation, since path
information easily gets stale.
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>
Cc: Rob Herring <robherring2@gmail.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
