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: [email protected]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：
[[email protected]am335x mnt]#cd [[email protected]-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 [[email protected]-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\n");
}
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\n", 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\n", 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\n", 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\n", 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\n", 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：
[[email protected] ]#cd mnt/ [[email protected]-am335x mnt]#ls LED_zixitong gpio_keys.ko leds-gpio.ko zyr-hello.ko gpio_buttons_leds led_test zleds-gpio.ko [[email protected]-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>;
时间： 2024-11-03 03:32:48