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| author | Jean Delvare <khali@linux-fr.org> | 2012-10-05 22:23:54 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@endymion.delvare> | 2012-10-05 22:23:54 +0200 |
| commit | e7ee51405835cac72e7b6e0ff26dba608cf186cc (patch) | |
| tree | cbc011e79a70e32475c3f7f4d91e5a6739eedfd0 /include/linux/i2c-mux-gpio.h | |
| parent | 2614a8594152cad49047ed02255a3d9fbbbea8dd (diff) | |
| download | linux-e7ee51405835cac72e7b6e0ff26dba608cf186cc.tar.gz linux-e7ee51405835cac72e7b6e0ff26dba608cf186cc.tar.xz | |
i2c-mux-gpio: Add support for dynamically allocated GPIO pins
The code instantiating an i2c-mux-gpio platform device doesn't
necessarily know in advance the GPIO pin numbers it wants to use. If
pins are on a GPIO device which gets its base GPIO number assigned
dynamically at run-time, the values can't be hard-coded.
In that case, let the caller tell i2c-mux-gpio the name of the GPIO
chip and the (relative) GPIO pin numbers to use. At probe time, the
i2c-mux-gpio driver will look for the chip and apply the proper offset
to turn relative GPIO pin numbers to absolute GPIO pin numbers.
The same could be (and was so far) done on the caller's end, however
doing it in i2c-mux-gpio has two benefits:
* It avoids duplicating the code on every caller's side (about 30
lines of code.)
* It allows for deferred probing for the muxed part of the I2C bus
only. If finding the GPIO chip is the caller's responsibility, then
deferred probing (if the GPIO chip isn't there yet) will not only
affect the mux and the I2C bus segments behind it, but also the I2C
bus trunk.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
Diffstat (limited to 'include/linux/i2c-mux-gpio.h')
| -rw-r--r-- | include/linux/i2c-mux-gpio.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/i2c-mux-gpio.h b/include/linux/i2c-mux-gpio.h index 4ea1cc7392bd..4406108201fe 100644 --- a/include/linux/i2c-mux-gpio.h +++ b/include/linux/i2c-mux-gpio.h @@ -22,6 +22,8 @@ * position * @n_values: Number of multiplexer positions (busses to instantiate) * @classes: Optional I2C auto-detection classes + * @gpio_chip: Optional GPIO chip name; if set, GPIO pin numbers are given + * relative to the base GPIO number of that chip * @gpios: Array of GPIO numbers used to control MUX * @n_gpios: Number of GPIOs used to control MUX * @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used @@ -32,6 +34,7 @@ struct i2c_mux_gpio_platform_data { const unsigned *values; int n_values; const unsigned *classes; + char *gpio_chip; const unsigned *gpios; int n_gpios; unsigned idle; |