中断方式按键驱动中引入poll机制

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <plat/gpio-fns.h>
#include <mach/gpio-nrs.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/gpio.h>
#include <linux/poll.h>

#define BUTTON_NUMS    4
#define IRQT_BOTHEDGE IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING

static int major;
static int event_trig = 0;

static unsigned char key_status;

static volatile unsigned long *gpfcon = NULL;
static volatile unsigned long *gpgcon = NULL;
static volatile unsigned long *gpfdat = NULL;
static volatile unsigned long *gpgdat = NULL;

static struct class *button_drv_class;
static struct class_device    *button_drv_class_dev;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

struct button_desc
{
    int pin;
    int irq_type;
    unsigned long flags;
    char *name;
    int key_val;
};

static struct button_desc btn_desc[BUTTON_NUMS] = {
    {S3C2410_GPF(0),  IRQ_EINT0,  IRQT_BOTHEDGE, "S2", 1},
    {S3C2410_GPF(2),  IRQ_EINT2,  IRQT_BOTHEDGE, "S3", 2},
    {S3C2410_GPG(3),  IRQ_EINT11, IRQT_BOTHEDGE, "S4", 3},
    {S3C2410_GPG(11), IRQ_EINT19, IRQT_BOTHEDGE, "S5", 4},
};

static int button_drv_open(struct inode *inode, struct file *file);
static ssize_t button_drv_read(struct file *file, char __user *buf, size_t count, loff_t *ppos);
static ssize_t button_drv_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos);
static int button_drv_close(struct inode *inode, struct file *file);
static unsigned button_drv_poll(struct file *file, poll_table *wait);

struct file_operations button_drv_fileop = {
    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open   =   button_drv_open,
    .read   =   button_drv_read,
    .write  =   button_drv_write,
    .release =  button_drv_close,
    .poll = button_drv_poll,
};

static irqreturn_t button_irq_handle(int irq, void *dev_id)
{    
    struct button_desc *pdesc = NULL;
    unsigned char pin_val;
    
    pdesc = (struct button_desc *)dev_id;
    
    pin_val = gpio_get_value(pdesc->pin);    

    if(pin_val == 1)
    {
        key_status = pdesc->key_val | 0x80;
    }
    else
    {
        key_status = pdesc->key_val;
    }
    
    event_trig = 1;
    wake_up_interruptible(&button_waitq); 
    
    return IRQ_RETVAL(IRQ_HANDLED);
}

static int button_drv_open(struct inode *inode, struct file *file)
{
    int i;
    
    *gpfcon &= ~((0x3<<(0*2)) | (0x3<<(2*2)));
    *gpgcon &= ~((0x3<<(3*2)) | (0x3<<(11*2)));
    
    /* 注册中断处理函数 */
    for(i = 0; i < BUTTON_NUMS; i++)
        request_irq(btn_desc[i].irq_type, button_irq_handle, btn_desc[i].flags, btn_desc[i].name, &btn_desc[i]);
    
    return 0;
}

static ssize_t button_drv_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
    if(count != 1)
        return EINVAL;
    
    wait_event_interruptible(button_waitq, event_trig);
    
    if(copy_to_user(buf, &key_status, count))
        return EFAULT;
    
    event_trig = 0;
    return 0;
}

static ssize_t button_drv_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
    printk("button_drv_write\n");
    
    return 0;
}

static int button_drv_close(struct inode *inode, struct file *file)
{
    int i;
    
    for(i = 0; i < BUTTON_NUMS; i++)
        free_irq(btn_desc[i].irq_type, &btn_desc[i]);
    
    return 0;
}

static unsigned button_drv_poll(struct file *file, poll_table *wait)
{
    unsigned int mask = 0;
    poll_wait(file, &button_waitq, wait); // 不会立即休眠

    if (event_trig)
        mask |= POLLIN | POLLRDNORM;

    return mask;
}
        
static int button_drv_init(void)
{
    major = register_chrdev(0, "button_light", &button_drv_fileop);
    
    button_drv_class = class_create(THIS_MODULE, "button_drv");
    //button_drv_class_dev = class_device_create(button_drv_class, NULL, MKDEV(major, 0), NULL, "button"); /* /dev/button */
    button_drv_class_dev = device_create(button_drv_class, NULL, MKDEV(major, 0), NULL, "button"); /* /dev/button */
    
    gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
    gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
    gpfdat = gpfcon + 1;
    gpgdat = gpgcon + 1;
    
    return 0;
}

static void button_drv_exit(void)
{
    unregister_chrdev(major, "button_drv");
    
    //class_device_unregister(button_drv_class_dev);
    device_unregister(button_drv_class_dev);
    class_destroy(button_drv_class);
    
    iounmap(gpfcon);
    iounmap(gpgcon);
}

module_init(button_drv_init);
module_exit(button_drv_exit);

MODULE_LICENSE("GPL");

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <poll.h>


int main(int argc, char **argv)
{
    int fd, ret;
    unsigned char key_buf;
    struct pollfd fds;
    
    fd = open("/dev/button", O_RDWR);
    if(fd == -1)
    {
        printf("can‘t open...\n");
        exit(EXIT_FAILURE);
    }
    
    fds.fd = fd;
    fds.events = POLLIN;
    
    while(1)
    {
        ret = poll(&fds, 1, 3000);
        if(ret > 0)
        {
            ret = read(fd, &key_buf, 1);
            if(ret < 0)
            {
                printf("read err...\n");
                continue;
            }
            /* 判断有按键按下，打印按键信息 */
            printf("key_val=0x%x\n", key_buf);
        }
        else if(ret == 0)
        {
            printf("time out...\n");
        }
        else if(ret == -1)
        {
            printf("error...\n");
        }
        
    }

    exit(EXIT_SUCCESS);
}