sunxi_pinctrl_desc_find_function_by_pin
desc = sunxi_pinctrl_desc_find_function_by_pin(pctl, pinnum, "irq");
func = sunxi_pinctrl_desc_find_function_by_pin(pctl,
desc = sunxi_pinctrl_desc_find_function_by_pin(pctl, pin, "irq");
desc = sunxi_pinctrl_desc_find_function_by_pin(pctl, offset, func);