Re: [PATCH v6] i2c-gpio: add devicetree support
From: Thomas Chou
Date: Thu Feb 24 2011 - 21:05:14 EST
On 02/25/2011 12:22 AM, Grant Likely wrote:
+- compatible : should be "i2c-gpio".
+- gpios : should specify GPIOs used for SDA and SCL lines, in that order.
+- sda-is-open-drain : present if SDA gpio is open-drain.
+- scl-is-open-drain : present if SCL gpio is open-drain.
+- scl-is-output-only : present if the output driver for SCL cannot be
+ turned off. this will prevent clock stretching from working.
+- speed-hz : SCL frequency.
One nitpick; I just looked, and other i2c controllers are already
using 'clock-frequency' instead of 'speed-hz' for the speed of the
bus. I'd like to see this patch use the same terminology.
I studied 'clock-frequency' usage of existing i2c drivers before working
on this patch.
i2c-ibm_iic.c, i2c-mpc.c, i2c-ocores.c : use as bus clock frequency
input to the core.
i2c-cpm.c : use as i2c SCL output frequency.
Most other non-i2c drivers use clock-frequency as bus clock frequency
I think the SCL freq usage in i2c-cpm.c is confusing. So I would suggest
we borrow 'speed-hz' from spi subsystem, which means the clock freq
output on the peripheral bus.
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