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i2c-mux-gpio: Update documentation 

* Document the possibility to pass relative GPIO pin numbers.
* Document what platform device IDs to use, so that they do not
  collide.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
This commit is contained in:
Jean Delvare 2012-10-05 22:23:54 +02:00 committed by Jean Delvare
parent e7ee514058
commit 600a711cfe
1 changed files with 18 additions and 0 deletions
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18
Documentation/i2c/muxes/i2c-mux-gpio
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@ -63,3 +63,21 @@ static struct platform_device myboard_i2cmux = {
.platform_data = &myboard_i2cmux_data,
},
};
If you don't know the absolute GPIO pin numbers at registration time,
you can instead provide a chip name (.chip_name) and relative GPIO pin
numbers, and the i2c-gpio-mux driver will do the work for you,
including deferred probing if the GPIO chip isn't immediately
available.
Device Registration
-------------------
When registering your i2c-gpio-mux device, you should pass the number
of any GPIO pin it uses as the device ID. This guarantees that every
instance has a different ID.
Alternatively, if you don't need a stable device name, you can simply
pass PLATFORM_DEVID_AUTO as the device ID, and the platform core will
assign a dynamic ID to your device. If you do not know the absolute
GPIO pin numbers at registration time, this is even the only option.