Linux Device Drivers Development

The descriptor-based GPIO interface – the new and recommended way

With the new descriptor-based GPIO interface, a GPIO is characterized by a coherent struct gpio_desc structure:

struct gpio_desc { 
   struct gpio_chip  *chip; 
   unsigned long flags; 
   const char *label; 
}; 

You should use the following header to be able to use the new interface:

#include <linux/gpio/consumer.h> 

With the descriptor-based interface, prior to allocating and taking the ownership of GPIOs, those GPIOs must have been mapped somewhere. By mapped, I mean they should be assigned to your device, whereas, with the legacy integer-based interface, you just have to fetch a number anywhere and request it as a GPIO. Actually, there are three kinds of mapping in the kernel:

• Platform ...