Re: pca953x GPIO

[Joan Pau Beltran <joanpau.beltran-i5CWTa81U/w@public.gmane.org>]

Hi everyone,

This mail is to let everybody notice that since kernel version 3.1, the 
pca953x module handles properly the chip WITHOUT the need of platform 
specific data. This means that, from user space, you can manage the pins 
through the /sys/class/gpio interface (provided by kernel's gpiolib 
framework) without building a new kernel with the platform code. You 
just need to read / write to the correct files. E.g.

# Register the chip on the proper bus.
# A new directory should whose name ends with a chip number N:
#   /sys/class/gpio/gpiochip240
echo pca9555 0x20 > /sys/bus/i2c/devices/i2c-0/new_device

# Request the wanted pin number M on the chip number N (chip number + 
pin number).
# A new directory should appear:
#   /sys/class/gpio/gpioN+M
echo 240 > /sys/class/gpio/export
echo 241 > /sys/class/gpio/export

# Get the pin state:
cat /sys/class/gpio/gpio240/value

# Set pin direction:
echo 'out' > /sys/class/gpio/gpio241/direction

# Set pin state:
echo '1' > /sys/class/gpio/gpio241/value

Regards,

-- 
Joan Pau Beltran
Grup de Sistemes, Robòtica i Visió - DMI
Universitat de les Illes Balears
Ctra. Valldemossa, km 7.5 07122 Palma
Campus Universitari, edifici Anselm Turmeda
Telf (+34) 971 17 28 13
Fax (+34) 971 17 30 03