Hi all,
I am currently using SDK 7.00 for am335x custom board, I am trying to read
the value of an input. I am using kernel 3.12 kernel. The only way I have
found is to manually export the gpio and then read the value but i want
read gpio buttons through sys. here i am using pre defined gpio drive
gpio_keys.c. find the device tree bellow...
gpio_keys_s0: gpio_keys_s0 {
pinctrl-single,pins = <
0x2c (PIN_INPUT_PULLUP | MUX_MODE7)
/*key_init GPIO0_27 */
0x20 (PIN_INPUT_PULLUP | MUX_MODE7) /*
Alaram_key GPIO0_22 */
0x28 (PIN_INPUT_PULLUP | MUX_MODE7) /*
Cancel_key GPIO0_26---- 0x28 */
0x24 (PIN_INPUT_PULLUP | MUX_MODE7) /*
Away_key GPIO0_23 */
>;
};
gpio_buttons: gpio_buttons@0 {
compatible = "gpio-keys";
pinctrl-names = "default";
pinctrl-0 = <&gpio_keys_s0>;
#address-cells = <1>;
#size-cells = <0>;
switch@1 {
label = "key_init";
debounce_interval = <50>;
linux,code = <100>;
gpios = <&gpio0 27 GPIO_ACTIVE_HIGH>;
gpio-key,wakeup;
};
switch@2 {
label = "Alaram_key";
linux,code = <0x102>;
gpios = <&gpio0 22 GPIO_ACTIVE_HIGH>;
};
switch@3 {
label = "Cancel_key";
linux,code = <0x103>;
gpios = <&gpio0 26 GPIO_ACTIVE_HIGH>;
gpio-key,wakeup;
};
switch@4 {
label = "Away_key";
linux,code = <0x108>;
gpios = <&gpio0 23 GPIO_ACTIVE_HIGH>;
};
};
I can see the the events occur in /dev/input/event0.
root@am335x-evm:/dev/input# cat event1
▒Dm8▒R
▒Dm8▒R
▒Dm8'S
▒Dm8'S
▒Dm8=
The problem is I need to read the value and not trigger off of an
interrupt. but i want read the value through sys file like leds output
root@am335x-evm:/sys/class/leds/beaglebone:green:usr3#
root@am335x-evm:/sys/class/leds/beaglebone:green:usr3# echo 1 >brightness
root@am335x-evm:/sys/class/leds/beaglebone:green:usr3# cat brightness
1
please help me how to read input gpio data as well as how to export gpio
buttons attributes to sys directory
Thankas & Regards
shankar
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