学步园

#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 <linux/irq.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>

#define DEVICE_NAME     "buttons"

struct button_irq_desc {                      //定义按键中断的结构体
    int irq;                                              //中断号
    int pin;                                              //按键引脚
    int pin_setting;                                 // 按键引脚设置（设置为中断）
    int number;                                      //按键编号
    char *name;                                     //按键名称
};

//利用结构体struct button_irq_desc 定义6个按键的信息，把按键的资源进行了组织

#if !defined (CONFIG_QQ2440_BUTTONS)
static struct button_irq_desc button_irqs [] = {
    {IRQ_EINT8 , S3C2410_GPG0 ,  S3C2410_GPG0_EINT8  , 0, "KEY0"},
    {IRQ_EINT11, S3C2410_GPG3 ,  S3C2410_GPG3_EINT11 , 1, "KEY1"},
    {IRQ_EINT13, S3C2410_GPG5 ,  S3C2410_GPG5_EINT13 , 2, "KEY2"},
    {IRQ_EINT14, S3C2410_GPG6 ,  S3C2410_GPG6_EINT14 , 3, "KEY3"},
    {IRQ_EINT15, S3C2410_GPG7 ,  S3C2410_GPG7_EINT15 , 4, "KEY4"},
    {IRQ_EINT19, S3C2410_GPG11,  S3C2410_GPG11_EINT19, 5, "KEY5"},
};
#else /* means QQ */
static struct button_irq_desc button_irqs [] = {
    {IRQ_EINT19, S3C2410_GPG11, S3C2410_GPG11_EINT19, 0, "KEY0"},
    {IRQ_EINT11, S3C2410_GPG3,  S3C2410_GPG3_EINT11,  1, "KEY1"},
    {IRQ_EINT2,  S3C2410_GPF2,  S3C2410_GPF2_EINT2,   2, "KEY2"},
    {IRQ_EINT0,  S3C2410_GPF0,  S3C2410_GPF0_EINT0,   3, "KEY3"},
    {       -1,            -1,                 -1,    4, "KEY4"},
    {       -1,            -1,                 -1,    5, "KEY5"},
};
#endif
static volatile char key_values [] = {'0', '0', '0', '0', '0', '0'};  //按键的状态（按下还是弹起）存储在这里

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);      //定义等待队列

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;   //定义了按键中断结构体指针
    int down;

    // udelay(0);
    down = !s3c2410_gpio_getpin(button_irqs->pin);                                   //读取按键引脚值取反赋给down

    if (down != (key_values[button_irqs->number] & 1)) { // Changed                   //如果引脚值发生改变

 key_values[button_irqs->number] = '0' + down;
 
        ev_press = 1;
        wake_up_interruptible(&button_waitq);
    }
   
    return IRQ_RETVAL(IRQ_HANDLED);
}

static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{
    int i;
    int err = 0;
   
    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {         //逐个扫描按键
 if (button_irqs[i].irq < 0) {                                                              //中断号小于0
  continue;                                                                            //跳出，直接执行下一个循环，扫描下一个按键
 }
        err = request_irq(button_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH,
                          button_irqs[i].name, (void *)&button_irqs[i]);
        if (err)
            break;
    }

    if (err) {
        i--;
        for (; i >= 0; i--) {
     if (button_irqs[i].irq < 0) {
  continue;
     }
     disable_irq(button_irqs[i].irq);
            free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
        }
        return -EBUSY;
    }

    ev_press = 1;
   
    return 0;
}

static int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
    int i;
   
    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {
 if (button_irqs[i].irq < 0) {
     continue;
 }
 free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);
    }

    return 0;
}

static int s3c24xx_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
     wait_event_interruptible(button_waitq, ev_press);
    }
   
    ev_press = 0;

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

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

static unsigned int s3c24xx_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;
}

static struct file_operations dev_fops = {
    .owner   =   THIS_MODULE,
    .open    =   s3c24xx_buttons_open,
    .release =   s3c24xx_buttons_close,
    .read    =   s3c24xx_buttons_read,
    .poll    =   s3c24xx_buttons_poll,
};

static struct miscdevice misc = {
 .minor = MISC_DYNAMIC_MINOR,
 .name = DEVICE_NAME,
 .fops = &dev_fops,
};

static int __init dev_init(void)
{
 int ret;

 ret = misc_register(&misc);

 printk (DEVICE_NAME"/tinitialized/n");

 return ret;
}

static void __exit dev_exit(void)
{
 misc_deregister(&misc);
}

module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");

1 中断处理

http://blog.chinaunix.net/u1/34474/showart_432711.html

       内核维护了一个中断信号线的注册表，类似于 I/O 端口的注册表。模块在使用中断前要先请求一个中断通道(或者 IRQ中断请求)，并在使用后释放它。所用的函数声明在 <linux/interrupt.h> (在此文件中并未真正包含，是通过它include的文件间接包含的，函数在/kernel/irq/Manage.h中)，中断注册和释放的函数接口如下:

request_irq 的返回值： 0 指示成功，或返回一个负的错误码，如 -EBUSY 表示另一个驱动已经占用了你所请求的中断线。

函数的参数如下:

中断处理例程可在驱动初始化时或在设备第一次打开时安装。推荐在设备第一次打开、硬件被告知产生中断前时申请中断，因为可以共享有限的中断资源。这样调用 free_irq 的位置是设备最后一次被关闭、硬件被告知不用再中断处理器之后。但这种方式的缺点是必须为每个设备维护一个打开计数。

http://blog.chinaunix.net/u2/88438/showart_2011915.html