在配置CONFIG_OF_GPIO下作用：

int of_gpiochip_add(struct gpio_chip *chip) {  int status;

 if ((!chip->of_node) && (chip->parent))   chip->of_node = chip->parent->of_node;

 if (!chip->of_node)   return 0;

 if (!chip->of_xlate) {   chip->of_gpio_n_cells = 2;   chip->of_xlate = of_gpio_simple_xlate;  }

 if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)   return -EINVAL;

 status = of_gpiochip_add_pin_range(chip);  if (status)   return status;

 /* If the chip defines names itself, these take precedence */  if (!chip->names)   of_gpiochip_set_names(chip);

 of_node_get(chip->of_node);

 return of_gpiochip_scan_gpios(chip); }

void of_gpiochip_remove(struct gpio_chip *chip) {  gpiochip_remove_pin_ranges(chip);  of_node_put(chip->of_node); }