nuc972-中断按键

添加按键中断

当前设备的gpio都是通过qgpio驱动控制的，只能使用轮询的方式检测，比较耗费CPU。此文档指导优化按键，使用中断的方式进行检测

注册设备

1. 进入内核中芯片对应的目录： 02.linux内核3.10.x/arch/arm/mach-nuc970

2. 修改dve.c,注册按键，按键为 NUC970_PI0~NUC970_PI11 共12个，添加如下：

   static struct gpio_keys_button n30_buttons[] = {
       {
           .gpio		= NUC970_PI0,
           .code		= KEY_A,
           .desc		= "KEY_A",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI1,
           .code		= KEY_B,
           .desc		= "KEY_B",
           .active_low	= 1,
       },
           {
           .gpio		= NUC970_PI2,
           .code		= KEY_L,
           .desc		= "KEY_L",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI3,
           .code		= KEY_C,
           .desc		= "KEY_C",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI4,
           .code		= KEY_D,
           .desc		= "KEY_D",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI5,
           .code		= KEY_E,
           .desc		= "KEY_E",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI6,
           .code		= KEY_F,
           .desc		= "KEY_F",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI7,
           .code		= KEY_G,
           .desc		= "KEY_G",
           .active_low	= 1,
       },
       {
           .gpio		= NUC970_PI8,
           .code		= KEY_H,
           .desc		= "KEY_H",
           .active_low	= 1,
       },
           {
           .gpio		= NUC970_PI9,
           .code		= KEY_I,
           .desc		= "KEY_I",
           .active_low	= 1,
       },
           {
           .gpio		= NUC970_PI10,
           .code		= KEY_J,
           .desc		= "KEY_J",
           .active_low	= 1,
       },
           {
           .gpio		= NUC970_PI11,
           .code		= KEY_K,
           .desc		= "KEY_K",
           .active_low	= 1,
       },
   };
   
   static struct gpio_keys_platform_data n30_button_data = {
       .buttons	= n30_buttons,
       .nbuttons	= ARRAY_SIZE(n30_buttons),
   };
   
   static struct platform_device n30_button_device = {
       .name		= "gpio-keys",
       .id		= -1,
       .dev		= {
           .platform_data	= &n30_button_data,
       }
   };

3. 初始化设备，在nuc970_public_dev[]数组中添加我们的按键设备：

   static struct platform_device *nuc970_public_dev[] __initdata = {
       &nuc970_serial_device0,
   
       //我们注册的设备
       &n30_button_device,
       
       // 后面的设备省略
   };

4. 添加头文件：

   #include <linux/gpio_keys.h>

打开驱动

使用make menuconfig命令配置内核，打开GPIO Buttons配置项：

Device Drivers  --->
    Input device support  --->
        [*]   Keyboards  --->
            <*>   GPIO Buttons

重编内核

使用make uImage编译内核

Image Name:   Linux-3.10.101
Created:      Fri Mar 24 16:07:17 2023
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    2881112 Bytes = 2813.59 kB = 2.75 MB
Load Address: 00008000
Entry Point:  00008000
  Image arch/arm/boot/uImage is ready
cp arch/arm/boot/uImage   ../image/970uimage

编译成功后得到970uimage

中断使用

NUC970_PI0~NUC970_PI11 12个按键的中断通过 /dev/input/event1 来获取，示例代码如下：

#include <stdio.h>
#include <fcntl.h>
#include <linux/input.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char* argv[])
{
        char devname[] = "/dev/input/event1";
        char devname_buf[64];
        int device;
        struct input_event ev;
        int read_size;
  
        device = open(devname, O_RDONLY);

        while(1)
        {
            read_size = read(device,&ev, sizeof(ev));
            if (read_size == sizeof(ev)) {
                printf("Key: %d State: %d\n",ev.code,ev.value);
            }
            else{
                printf("read error\n");
            }
        }
        close(device);
        
        return 0;
}