Allow setting of GPIO pin names.

[loos]

Summary

Add two new gpiobus methods to get and set GPIO pin names.

When a pin name is set, we do a lazy allocation and store the user supplied string.

When a pin name is read, the gpiobus getname method will return the stored value if any, and the default name otherwise.

Make the necessary modifications to libgpio and gpioctl.

When a gpiobus child is added, use its name to identify the gpio pin name.

[rpaulo]

lib/libgpio/gpio.c

122

I'm thinking it might be better to just write this function with a (gpio_handle_t, unsigned int pin, const char *name) instead of passing the gpio config.

sys/dev/gpio/gpiobus.c

691

This can probably be M_WAITOK.

[loos]

Change the parameters of libgpio's function gpio_pin_set_name().

Change the memory allocation of GPIO pin name to M_WAITOK.

[rpaulo]

lib/libgpio/gpio.c

124

Should we bzero this variable?

[loos]

Thanks Rui!

lib/libgpio/gpio.c

124

Yes, it is better to bzero it first. I'll fix it before commit.

[loos]

Closed by commit rS279761 (authored by @loos).