控制gpio
方式一：通过dtsi
方式二：通过通用gpio子系统
内核查看gpio的状态/sys/kernel/debug/gpio
gpiochip3: GPIOs 884-895, parent: platform/c440000.qcom,spmi:qcom,pm7250b@2:pinctrl@c000, c440000.qcom,spmi:qcom,pm7250b@2:pinctrl@c000:
gpio1 : in low normal vin-0 pull-down 10uA push-pull high atest-1 dtest-0
gpio2 : out high normal vin-0 pull-down 10uA push-pull high atest-1 dtest-0
gpio3 : in low normal vin-0 pull-down 10uA push-pull high atest-1 dtest-0
gpio4 : in low normal vin-0 pull-down 10uA push-pull high atest-1 dtest-0
gpio5 : out low normal vin-1 pull-down 10uA open-drain high atest-1 dtest-0
gpio6 : in low normal vin-0 pull-down 10uA push-pull high atest-1 dtest-3
gpio7 : in low normal vin-0 pull-down 10uA push-pull high atest-1 dtest-0
gpio8 : in low normal vin-0 pull-down 10u