I am trying to access gpio expander max7321 in our custom board with WP7608. I can see a bug in Sierra wireless kernel code.
The gpio expander is listed as gpiochip812 successfully in /sys/class/gpio path. And i am trying to export that pin:
echo 812 > /sys/class/gpio/export
This command returns error. Because kernel allows to export only processor gpio pins. The function gpio_map_name_to_num in drivers/gpio/gpiolib-sysfs.c blocks gpios expander pins. The gpio_map_name_to_num() is Sierra Wireless code.
Could you please help me to add gpio expander access from Linux user space?.