1. /sys/kernel/debug/gpio
可以实时反馈系统中感兴趣的gpio引脚的状态
root@g6s:/sys/kernel/debug# cat gpio gpiochip7: GPIOs 356-359, parent: platform/e6055800.gpio, e6055800.gpio: gpio-359 ( |IPOD.Reset ) out hi gpiochip6: GPIOs 360-391, parent: platform/e6055400.gpio, e6055400.gpio: gpio-364 ( |pdn ) out hi gpio-366 ( |stb ) out hi gpio-367 ( |reverse detect ) in lo IRQ gpio-381 ( |pwdn ) out hi gpio-384 ( |USB20_VBUS0 ) out hi gpio-386 ( |USB20_VBUS1 ) out hi gpio-388 ( |max9281-powerdown ) out hi gpio-389 ( |? ) in hi IRQ gpio-390 ( |max9275-powerdown ) out hi gpiochip5: GPIOs 392-417, parent: platform/e6055000.gpio, e6055000.gpio: gpio-399 ( |GPIO Key Power Low ) in hi IRQ gpio-400 ( |mcu-irq ) in hi IRQ gpio-411 ( |mcu-cs ) out hi gpiochip4: GPIOs 418-435, parent: platform/e6054000.gpio, e6054000.gpio: gpio-434 ( |backlight_main ) out hi gpio-435 ( |backlight_vice ) out hi gpiochip3: GPIOs 436-451, parent: platform/e6053000.gpio, e6053000.gpio: gpio-442 ( |tuner_switch ) out hi gpio-448 ( |cd ) in hi IRQ gpio-450 ( |BT.Reset ) out hi gpiochip2: GPIOs 452-466, parent: platform/e6052000.gpio, e6052000.gpio: gpio-455 ( |clipping ) in hi gpio-458 ( |sv-watchdog ) out lo gpio-462 ( |reset ) out hi gpiochip1: GPIOs 467-495, parent: platform/e6051000.gpio, e6051000.gpio: gpio-476 ( |camera lock ) in hi IRQ gpio-493 ( |cs ) out hi