Linux Device Drivers Development

Allocating and using GPIO

You can use either gpiog_get() or gpiod_get_index() to allocate a GPIO descriptor:

struct gpio_desc *gpiod_get_index(struct device *dev, 
                                 const char *con_id, 
                                 unsigned int idx, 
                                 enum gpiod_flags flags) 
struct gpio_desc *gpiod_get(struct device *dev, 
                            const char *con_id, 
                            enum gpiod_flags flags) 

On error, these functions will return -ENOENT if no GPIO with the given function is assigned, or another error on which you can use the IS_ERR() macro. The first function returns the GPIO descriptor structure that corresponds to the GPIO at a given index, whereas the second function returns the GPIO at index 0 (useful for one-GPIO mapping). dev is the device to which the GPIO descriptor will belong. It is your device. con_id