MINI2440_BUTTON.C

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/delay.h>

#include <linux/poll.h>

#include <asm/irq.h>

#include <linux/interrupt.h>

#include <asm/uaccess.h>

#include <asm/arch/regs-gpio.h>

#include <asm/hardware.h>

 

#define DEVICE_NAME     "buttons"   /* 加载模式后，执行”cat /proc/devices”命令看到的设备名称 */

#define BUTTON_MAJOR    232         /* 主设备号 */

 

struct button_irq_desc {

    int irq;

       int pin;

       int pin_setting;

       int number;

    char *name;   

};

 

/* 用来指定按键所用的外部中断引脚及中断触发方式, 名字 */

static struct button_irq_desc button_irqs [] = {

    {IRQ_EINT8, S3C2410_GPG0, S3C2410_GPG0_EINT8, 0, "KEY1"}, /* K1 */

    {IRQ_EINT11, S3C2410_GPG3,  S3C2410_GPG3_EINT11,  1, "KEY2"}, /* K2 */

    {IRQ_EINT13,  S3C2410_GPG5,  S3C2410_GPG5_EINT13,   2, "KEY3"}, /* K3 */

    {IRQ_EINT14,  S3C2410_GPG6,  S3C2410_GPG6_EINT14,   3, "KEY4"}, /* K3 */

    {IRQ_EINT15,  S3C2410_GPG7,  S3C2410_GPG7_EINT15,   4, "KEY5"}, /* K3 */

    {IRQ_EINT19,  S3C2410_GPG11,  S3C2410_GPG11_EINT19,   5, "KEY6"}, /* K4 */

};

 

/* 按键被按下的次数(准确地说，是发生中断的次数) */

static volatile int key_values [] = {0, 0, 0, 0, 0, 0};

 

/* 等待队列:

 * 当没有按键被按下时，如果有进程调用mini2440_buttons_read函数，

 * 它将休眠

 */

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

 

/* 中断事件标志, 中断服务程序将它置1，mini2440_buttons_read将它清0 */

static volatile int ev_press = 0;

 

 

static irqreturn_t buttons_interrupt(int irq, void *dev_id)

{

    struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id;

    int up = s3c2410_gpio_getpin(button_irqs->pin);

 

       if (up)

              key_values[button_irqs->number] = (button_irqs->number + 1) + 0x80;

       else

              key_values[button_irqs->number] = (button_irqs->number + 1);

      

    ev_press = 1;                  /* 表示中断发生了 */

    wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */

   

    return IRQ_RETVAL(IRQ_HANDLED);

}

 

 

/* 应用程序对设备文件/dev/buttons执行open(...)时，

 * 就会调用mini2440_buttons_open函数

 */

static int mini2440_buttons_open(struct inode *inode, struct file *file)

{

    int i;

    int err;

   

    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {

        // 注册中断处理函数

              s3c2410_gpio_cfgpin(button_irqs[i].pin,button_irqs[i].pin_setting);

        err = request_irq(button_irqs[i].irq, buttons_interrupt, NULL,

                          button_irqs[i].name, (void *)&button_irqs[i]);

              set_irq_type(button_irqs[i].irq, IRQT_BOTHEDGE);

        if (err)

            break;

    }

 

    if (err) {

        // 释放已经注册的中断

        i--;

        for (; i >= 0; i--) {

                     disable_irq(button_irqs[i].irq);

            free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);

        }

        return -EBUSY;

    }

   

    return 0;

}

 

 

/* 应用程序对设备文件/dev/buttons执行close(...)时，

 * 就会调用mini2440_buttons_close函数

 */

static int mini2440_buttons_close(struct inode *inode, struct file *file)

{

    int i;

   

    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {

        // 释放已经注册的中断

              disable_irq(button_irqs[i].irq);

        free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);

    }

 

    return 0;

}

 

 

/* 应用程序对设备文件/dev/buttons执行read(...)时，

 * 就会调用mini2440_buttons_read函数

 */

static int mini2440_buttons_read(struct file *filp, char __user *buff,

                                         size_t count, loff_t *offp)

{

    unsigned long err;

 

       if (!ev_press) {

              if (filp->f_flags & O_NONBLOCK)

                     return -EAGAIN;

              else

                     /* 如果ev_press等于0，休眠 */

                     wait_event_interruptible(button_waitq, ev_press);

       }

   

    /* 执行到这里时，ev_press等于1，将它清0 */

    ev_press = 0;

 

    /* 将按键状态复制给用户，并清0 */

    err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));

    memset((void *)key_values, 0, sizeof(key_values));

 

    return err ? -EFAULT : min(sizeof(key_values), count);

}

 

/**************************************************

* 当用户程序调用select函数时，本函数被调用

* 如果有按键数据，则select函数会立刻返回

* 如果没有按键数据，本函数使用poll_wait等待

**************************************************/

static unsigned int mini2440_buttons_poll(

        struct file *file,

        struct poll_table_struct *wait)

{

       unsigned int mask = 0;

    poll_wait(file, &button_waitq, wait);

    if (ev_press)

        mask |= POLLIN | POLLRDNORM;

    return mask;

}

 

 

/* 这个结构是字符设备驱动程序的核心

 * 当应用程序操作设备文件时所调用的open、read、write等函数，

 * 最终会调用这个结构中的对应函数

 */

static struct file_operations mini2440_buttons_fops = {

    .owner   =   THIS_MODULE,    /* 这是一个宏，指向编译模块时自动创建的__this_module变量 */

    .open    =   mini2440_buttons_open,

    .release =   mini2440_buttons_close,

    .read    =   mini2440_buttons_read,

       .poll =   mini2440_buttons_poll,

};

 

/*

 * 执行“insmod mini2440_buttons.ko”命令时就会调用这个函数

 */

static int __init mini2440_buttons_init(void)

{

    int ret;

 

    /* 注册字符设备驱动程序

     * 参数为主设备号、设备名字、file_operations结构；

     * 这样，主设备号就和具体的file_operations结构联系起来了，

     * 操作主设备为BUTTON_MAJOR的设备文件时，就会调用mini2440_buttons_fops中的相关成员函数

     * BUTTON_MAJOR可以设为0，表示由内核自动分配主设备号

     */

    ret = register_chrdev(BUTTON_MAJOR, DEVICE_NAME, &mini2440_buttons_fops);

    if (ret < 0) {

      printk(DEVICE_NAME " can't register major number\n");

      return ret;

    }

       devfs_mk_cdev(MKDEV(BUTTON_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, DEVICE_NAME);

   

    printk(DEVICE_NAME " initialized\n");

    return 0;

}

 

/*

 * 执行”rmmod mini2440_buttons.ko”命令时就会调用这个函数

 */

static void __exit mini2440_buttons_exit(void)

{

    /* 卸载驱动程序 */

       devfs_remove(DEVICE_NAME);

    unregister_chrdev(BUTTON_MAJOR, DEVICE_NAME);

}

 

/* 这两行指定驱动程序的初始化函数和卸载函数 */

module_init(mini2440_buttons_init);

module_exit(mini2440_buttons_exit);

 

/* 描述驱动程序的一些信息，不是必须的 */

MODULE_AUTHOR("http://www.arm9.net");             // 驱动程序的作者

MODULE_DESCRIPTION("S3C2410/S3C2440 BUTTON Driver");   // 一些描述信息

MODULE_LICENSE("GPL");                              // 遵循的协议

 

总结一下，程序框架。

按键的驱动主要是多了中断的处理，关于中断主要的处理函数是

 

request_irq(button_irqs[i].irq, buttons_interrupt, NULL,

button_irqs[i].name, (void *)&button_irqs[i]);

第二个参数是主要的中断处理函数。

static irqreturn_t buttons_interrupt(int irq, void *dev_id)

{

    struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id;

    int up = s3c2410_gpio_getpin(button_irqs->pin);

 

       if (up)

              key_values[button_irqs->number] = (button_irqs->number + 1) + 0x80;

       else

              key_values[button_irqs->number] = (button_irqs->number + 1);

      

    ev_press = 1;                  /* 表示中断发生了 */

    wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */

   

    return IRQ_RETVAL(IRQ_HANDLED);

}

另外还用到了两个重要的结构体：

static struct button_irq_desc button_irqs [] = {

    {IRQ_EINT8, S3C2410_GPG0, S3C2410_GPG0_EINT8, 0, "KEY1"}, /* K1 */

    {IRQ_EINT11, S3C2410_GPG3,  S3C2410_GPG3_EINT11,  1, "KEY2"}, /* K2 */

    {IRQ_EINT13,  S3C2410_GPG5,  S3C2410_GPG5_EINT13,   2, "KEY3"}, /* K3 */

    {IRQ_EINT14,  S3C2410_GPG6,  S3C2410_GPG6_EINT14,   3, "KEY4"}, /* K3 */

    {IRQ_EINT15,  S3C2410_GPG7,  S3C2410_GPG7_EINT15,   4, "KEY5"}, /* K3 */

    {IRQ_EINT19,  S3C2410_GPG11,  S3C2410_GPG11_EINT19,   5, "KEY6"}, /* K4 */

};

struct button_irq_desc {

    int irq;

       int pin;

       int pin_setting;

       int number;

    char *name;   

};

而驱动程序中的最重要的部分，file_operations为

static struct file_operations mini2440_buttons_fops = {

    .owner   =   THIS_MODULE,    /* 这是一个宏，指向编译模块时自动创建的__this_module变量 */

    .open    =   mini2440_buttons_open,

    .release =   mini2440_buttons_close,

    .read    =   mini2440_buttons_read,

       .poll =   mini2440_buttons_poll,

};

程序中其他的任务就是丰满这个机构体，使得应用程序在调用open，close等的时候可以在

驱动中找到对应的项。

这里的request_irq在open函数里调用的。

至于注册的部分跟LEDS那些是一样的，就不多说啦。

再附个应用程序供参考：

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/ioctl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <sys/select.h>

#include <sys/time.h>

#include <errno.h>

 

int main(void)

{

       int i;

       int buttons_fd;

       int key_value[4];

 

       /*打开键盘设备文件*/

       buttons_fd = open("/dev/buttons", 0);

       if (buttons_fd < 0) {

              perror("open device buttons");

              exit(1);

       }

 

       for (;;) {

              fd_set rds;

              int ret;

 

              FD_ZERO(&rds);

              FD_SET(buttons_fd, &rds);

 

              /*使用系统调用select检查是否能够从/dev/buttons设备读取数据*/

              ret = select(buttons_fd + 1, &rds, NULL, NULL, NULL);

             

              /*读取出错则退出程序*/

              if (ret < 0) {

                     perror("select");

                     exit(1);

              }

        

              if (ret == 0) {

                     printf("Timeout.\n");

              }

              /*能够读取到数据*/

              else if (FD_ISSET(buttons_fd, &rds)) {

                     /*开始读取键盘驱动发出的数据，注意key_value和键盘驱动中定义为一致的类型*/

                     int ret = read(buttons_fd, key_value, sizeof key_value);

                     if (ret != sizeof key_value) {

                            if (errno != EAGAIN)

                                   perror("read buttons\n");

                            continue;

                     } else {

                            /*打印键值*/

                            for (i = 0;i < sizeof(key_value)/sizeof(key_value[0]); i++)

                                printf("K%d %s, key value = 0x%02x\n", i+1, (key_value[i] & 0x80) ? "released"     : \

                                                                                        key_value[i] ? "pressed down" : "", \

                                                                                key_value[i]);

                     }

                           

              }

       }

 

       /*关闭设备文件句柄*/

       close(buttons_fd);

       return 0;

}