리눅스에서 GPIO-KEY사용방법(AM65XX)

1. device tree에 gpio-key 추가
   • / {
     • gpio-keys {
       • compatible = "gpio-keys";
       • autorepeat;
       • pinctrl-names = "default";
       • pinctrl-0 = <&push_button_pins_default>;
       • sw5 {
         • label = "GPIO Key USER1";
         • linux,code = <BTN_0>; //BTN_0=0x100
         • gpios = <&wkup_gpio0 24 GPIO_ACTIVE_LOW>; //<0x07 0x18 0x01>;
       • };
       • sw6 {
         • label = "GPIO Key USER2";
         • linux,code = <BTN_1>; //BTN_1=0x101
         • gpios = <&wkup_gpio0 27 GPIO_ACTIVE_LOW>; //<0x07 0x1b 0x01>;
       • };
     • };
   • };
   • &wkup_pmx0 {
     • wkup_i2c0_pins_default: wkup-i2c0-pins-default {
       • pinctrl-single,pins = <
         • AM65X_WKUP_IOPAD(0x00e0, PIN_INPUT, 0) /* (AC7) WKUP_I2C0_SCL */
         • AM65X_WKUP_IOPAD(0x00e4, PIN_INPUT, 0) /* (AD6) WKUP_I2C0_SDA */
       • >;
     • };
push_button_pins_default: push-button-pins-default {
       • pinctrl-single,pins = <
         • AM65X_WKUP_IOPAD(0x0030, PIN_INPUT, 7) /* (R5) WKUP_GPIO0_24 */
         • AM65X_WKUP_IOPAD(0x003c, PIN_INPUT, 7) /* (P2) WKUP_GPIO0_27 */
       • >;
     • };
   • };
2. 확인 방법
   • $ cat /proc/bus/input/devices
   • I: Bus=0019 Vendor=0001 Product=0001 Version=0100
   • N: Name=”gpio-keys”
   • P: Phys=gpio-keys/input0
   • S: Sysfs=/devices/platform/gpio-keys/input/input0
   • U: Uniq=
   • H: Handlers=event0
   • B: PROP=0
   • B: EV=100003
   • B: KEY=3 0 0 0 0
   • $cat /sys/class/input/event0/uevent
   • MAJOR=13
   • MINOR=64
   • DEVNAME=input/event0
   • $mknod /dev/gpio-keys c 13 64
   • $hexdump /dev/gpio-keys
   • 0000000 bf9e 67f0 0000 0000 4d50 000b 0000 0000
   • 0000010 0001 0100 0001 0000 bf9e 67f0 0000 0000
   • 0000020 4d50 000b 0000 0000 0000 0000 0000 0000
   • 0000030 bf9e 67f0 0000 0000 33e7 000d 0000 0000
   • 0000040 0001 0100 0000 0000 bf9e 67f0 0000 0000
   • 0000050 33e7 000d 0000 0000 0000 0000 0000 0000