ARM Linux 驱动Input子系统之按键驱动测试

上一篇已经谈过，在现内核的中引入设备树之后对于内核驱动的编写，主要集中在硬件接口的配置上了即xxxx.dts文件的编写。

在自己的开发板上移植按键驱动：

1、根据开发板的原理图

确定按键的硬件接口为：GPIO2_2、GPIO2_3、GPIO2_5、GPIO0_30。

修改dts文件使其与原理图的按键接口一致。

gpio_buttons: gpio_buttons@0 {
        compatible = "gpio-keys";
        #address-cells = <1>;
        #size-cells = <0>;

        switch@1 {
            label = "button0";
            linux,code = <0x100>;
            gpios = <&gpio2 3 GPIO_ACTIVE_HIGH>;
        };

        switch@2 {
            label = "button1";
            linux,code = <0x101>;
            gpios = <&gpio2 2 GPIO_ACTIVE_HIGH>;
        };

        switch@3 {
            label = "button2";
            linux,code = <0x102>;
            gpios = <&gpio0 30 GPIO_ACTIVE_HIGH>;
            gpio-key,wakeup;
        };

        switch@4 {
            label = "button3";
            linux,code = <0x103>;
            gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>;
        };
    };

gpio_keys_s0: gpio_keys_s0 {
        pinctrl-single,pins = <
            0x94 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_oen_ren.gpio2_3 */
            0x90 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_advn_ale.gpio2_2 */
            0x70 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_wait0.gpio0_30 */
            0x9c (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ben0_cle.gpio2_5 */
        >;
    };

保存编译生成zyr-am335x-evmsk.dtb

在内核中确保xxx/linux3.14.65/drivers/input/keyboard/gpio_key.c被编译进去（可以通过各层的Makefile与Kconfig还有menuconfig来实现）

编译好的内核和dtb文件下载到开发板中查看按键的事件类型：

[root@zyr-am335x mnt]#cd
[root@zyr-am335x ]#cat /proc/bus/input/devices
I: Bus=0019 Vendor=0001 Product=0001 Version=0100
N: Name="gpio_buttons.7"
P: Phys=gpio-keys/input0
S: Sysfs=/devices/gpio_buttons.7/input/input0
U: Uniq=
H: Handlers=event0
B: PROP=0
B: EV=3
B: KEY=f 0 0 0 0 0 0 0 0

[root@zyr-am335x ]#

可以看到按键的事件或者是用户接口吧为event0.。知道了用户的按键接口就可以编写测试程序了。

测试程序目的：实现一个按键对应一个LED灯，按键按一次LED灯的状态变化一次（前提是led子系统对应的LED驱动已经加载入内核中）：

#include <stdio.h>
#include <linux/input.h>
#include <fcntl.h>
#include <sys/time.h>
#include <unistd.h>

void keyboard_test()
{
    int count_sw1 = 0;
    int count_sw2 = 0;
    int count_sw3 = 0;
    int count_sw4 = 0;
    int fd=open("/dev/input/event0",O_RDWR);
    if( fd <= 0 )
    {
        printf("Can not open keyboard input file
");
    }
    
    struct input_event *event;
    char buf[128] = {0};
    fd_set rfds;
    FD_ZERO(&rfds);
    FD_SET(fd, &rfds);
    
    while(1)
    {
        int ret = select(fd + 1,&rfds, NULL,NULL,NULL);
        if(ret < 0)
            continue;
        if( FD_ISSET(fd, &rfds) )
        {
            int readn = read(fd, buf, sizeof(struct input_event));
            if (readn <= 0)
            {
                printf("uart read error %d
", readn);
                continue;
            }
            
            struct input_event *my_event=(struct input_event*)buf;
            if(my_event->type == EV_KEY)
            {
                switch( my_event->code )
                {
                    case 256:
                        printf("This is a button:%d %d
", my_event->code,my_event->value);
                        count_sw1++;
                        if(count_sw1==1)
                        {
                            system("echo 1 > /sys/class/leds/zyrD1:green:usr0/brightness");
                        }
                        else if(count_sw1==4)
                        {
                            system("echo 0 > /sys/class/leds/zyrD1:green:usr0/brightness");
                            count_sw1=0;
                        }
                        break;
                    case 257:
                        printf("This is a button:%d %d
", my_event->code,my_event->value);
                        count_sw2++;
                        if(count_sw2==1)
                        {
                            system("echo 1 > /sys/class/leds/zyrD2:green:usr1/brightness");
                        }
                        else if(count_sw2==4)
                        {
                            system("echo 0 > /sys/class/leds/zyrD2:green:usr1/brightness");
                            count_sw2=0;
                        }
                        break;
                    case 258:
                        printf("This is a button:%d %d
", my_event->code,my_event->value);
                        count_sw3++;
                        if(count_sw3==1)
                        {
                            system("echo 1 > /sys/class/leds/zyrD3:green:heartbeat/brightness");
                        }
                        else if(count_sw3==4)
                        {
                            system("echo 0 > /sys/class/leds/zyrD3:green:heartbeat/brightness");
                            count_sw3=0;
                        }
                        break;
                    case 259:
                        printf("This is a button:%d %d
", my_event->code,my_event->value);
                        count_sw4++;
                        if(count_sw4==1)
                        {
                            system("echo 1 > /sys/class/leds/zyrD4:green:mmc0/brightness");
                        }
                        else if(count_sw4==4)
                        {
                            system("echo 0 > /sys/class/leds/zyrD4:green:mmc0/brightness");
                            count_sw4=0;
                        }
                        break;
                    default:
                        break;
                    
                }
            }
    
        }
        
    }
}

int main()
{
    keyboard_test();
    return 0;
}

将生成的可执行文件copy到nfs的共享目录下运行：

[root@zyr-am335x ]#cd mnt/
[root@zyr-am335x mnt]#ls
LED_zixitong       gpio_keys.ko       leds-gpio.ko       zyr-hello.ko
gpio_buttons_leds  led_test           zleds-gpio.ko
[root@zyr-am335x mnt]#./gpio_buttons_leds
This is a button:257 1
This is a button:257 0
This is a button:258 1
This is a button:258 0
This is a button:259 1
This is a button:259 0
This is a button:256 1
This is a button:256 0
This is a button:256 1
This is a button:256 0
This is a button:257 1
This is a button:257 0
This is a button:258 1
This is a button:258 0
This is a button:259 1
This is a button:259 0
其中的256,257,258,259分别对应dts文件中的linux,code = <0x101>;linux,code = <0x102>;linux,code = <0x103>;linux,code = <0x104>;