Linux_arm驱动之按键模拟脉冲实现定时器的精确计时 （实例）

/*****************************************************************
                       内核驱动部分button_ker.c
*****************************************************************/

/*
 *应用内核定时器简单实现计时的功能
 *但是内核定时器精确度最小就为50ms
 *较4_button_timer完善功能：利用硬件的定时器计时
 *精确度提高
 *应用linux-2.6.32.2内核里arch/arm/plat_s3/timer.c
 *实现对定时器的精确提高问题
 */
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

//*****///
#include
#include
#include
///****///
#include
#include
//#include
//#include
//#include

#include
#define DEVICE_NAME "timer_test"
#define BUTTON_MAJOR 240

#define TIMER_IOCTL_SET_FREQ  1
#define TIMER_IOCTL_STOP      0

static struct semaphore lock;

struct button_irq_desc{
    int irq;
    unsigned long flags;
    int num;
    char *name;
};
//用来指定按键所有的外部中断引脚以及中断出发方式和名字
static struct button_irq_desc button_irqs[] = {
    {IRQ_EINT0,IRQF_TRIGGER_FALLING,1,"KEY1"},
    {IRQ_EINT1,IRQF_TRIGGER_FALLING,2,"KEY2"},
    {IRQ_EINT2,IRQF_TRIGGER_FALLING,3,"KEY3"},
    {IRQ_EINT4,IRQF_TRIGGER_FALLING,4,"KEY4"},
};
static volatile char key_values[4]={'0','0','0','0'};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press =0;

static void timer_open(void);
static void timer_stop(void);
static inline int timer_interrupt_pending(void);
static unsigned long get_timer_offset(void);
///********************************////
static volatile bool value=false;
static volatile unsigned long count = 0;
static volatile unsigned long freq_value = 500;
static volatile unsigned long tcnt_value = 50625;
//定时器中断函数
static irqreturn_t timer_interrupt_function(int irq,void *dev_id)
{
    count++;
    //printk("timer_interrupt occur!\n");
    return IRQ_HANDLED;
}
//时间处理函数
static void timer_second_manage(unsigned long second_value)
{
    static volatile unsigned long ss_value1 = 0;
    static volatile unsigned long ms_value2 = 0;
    static volatile unsigned long us_value3 = 0;

    us_value3 = //(second_value*10000/tcnt_value)*1000/freq_value/10;
                    (second_value*1000/freq_value)*10000/tcnt_value/10;

    ms_value2 = (count%freq_value)*1000/freq_value + us_value3/1000;
    ss_value1 = count/freq_value + ms_value2/1000;

    printk("++++++++++++++++++++++++\n");
    printk("used time:%lu n\n",count);
    printk("the second_value :%lu n\n",second_value);
    printk("used time:%lu.%03lu %03lu s\n",ss_value1,
                                ms_value2%1000,us_value3%1000);
    printk("++++++++++++++++++++++++\n");

}
//外部中断函数
static irqreturn_t button_interrupt(int irq,void *dev_id){
    unsigned long second_value = 0;
    int num= ((struct button_irq_desc *)dev_id)->num;
    switch(num){
        case 2://17
            value=false;
            timer_stop();
            printk("key1 press\n");
            break;
        case 4://48
            if(!value) {
                value=true; count=0;
                timer_open();
            }else {
                timer_stop();
                second_value=get_timer_offset();
                timer_second_manage(second_value);
                value=false;
            }
            printk("key2 press\n");
            break;
        case 3://18
            value=false;
            timer_stop();
            printk("key3 press\n");
            break;
        case 1://16
            value=false;
            timer_stop();
            printk("key4 press\n");
            break;
        default:
            printk("num error,nothing to do!\n");

    }
    //ev_press=1;
    //wake_up_interruptible(&button_waitq);
    return IRQ_HANDLED;
}

//频率设置函数
//freq: pclk/50/16/65536~pclk/50/16
//if  : pclk=50mhz freq is 1Hz~62500Hz
//human ear : 20Hz~20000Hz
//
static void timer_set_freq(unsigned long freq)
{
    unsigned long tcon;
    unsigned long tcnt;
    unsigned long tcfg0;
    unsigned long tcfg1;

    struct clk *clk_p;
    unsigned long pclk;

    tcon  = __raw_readl(S3C2410_TCON);
    tcfg0 = __raw_readl(S3C2410_TCFG0);
    tcfg1 = __raw_readl(S3C2410_TCFG1);

    tcfg0 &= ~(255<<0);
    //tcfg0 |= (50-1);
    tcfg0 |= 0;

    tcfg1 &= ~(15<<0);
    tcfg1 |= (0<<0);

    __raw_writel(tcfg0,S3C2410_TCFG0);
    __raw_writel(tcfg1,S3C2410_TCFG1);

    clk_p = clk_get(NULL,"pclk");
    pclk  = clk_get_rate(clk_p);
    printk("the pclk is : %ld\n",pclk);
    //tcnt  = (pclk/50/16)/freq;
    tcnt  = (pclk/2)/freq;
    tcnt_value = tcnt;
    printk("the tcnt is %ld\n",tcnt);
     __raw_writel(tcnt,S3C2410_TCNTB(0));
     __raw_writel(0,S3C2410_TCMPB(0));

    //tcon &= ~0x1f;
    tcon &= ~0x1e;
    tcon |=0xb;

     __raw_writel(tcon,S3C2410_TCON);
    tcon &= ~2;
    __raw_writel(tcon,S3C2410_TCON);

}
static void timer_open(void)
{
    unsigned long tcon = 0;
    //printk("***1>tcnto is :%u\n",__raw_readl(S3C2410_TCNTO(0)));
    tcon = __raw_readl(S3C2410_TCON);
    tcon |= 1;
    __raw_writel(tcon,S3C2410_TCON);
    //printk("***2>tcnto is :%u\n",__raw_readl(S3C2410_TCNTO(0)));

}
static void timer_stop(void)
{
    unsigned long tcon;
    tcon = __raw_readl(S3C2410_TCON);
    tcon &= ~1;
    __raw_writel(tcon,S3C2410_TCON);

}
#define SRCPND_TIMER0 (1<<(IRQ_TIMER0 - IRQ_TIMER0))
//中断识别函数 查看在按键产生中断时，定时器是否也在中断中
static inline int timer_interrupt_pending(void)
{
    return __raw_readl(S3C2410_SRCPND) & SRCPND_TIMER0;
}
//计算中断寄存器中TCNTO0中的偏移量
static unsigned long get_timer_offset (void)
{
    unsigned long tdone;
    unsigned long tval;

    tdone = (tcnt_value -__raw_readl(S3C2410_TCNTO(0)));
    if(timer_interrupt_pending()) {
        tval = __raw_readl(S3C2410_TCNTO(0));
        tdone = tcnt_value - tval;
        if(!tval)
            tdone += tcnt_value;
    }
    return tdone;

}
static struct irqaction timer_irq = {
    .name    = "S3C2410 Timer Tick",
    .flags   = IRQF_DISABLED |IRQF_TIMER|IRQF_IRQPOLL,
    .handler = timer_interrupt_function,
    .dev_id  = NULL
};

static int button_open(struct inode *inode,struct file *file)
{

    int i,err;
    if(down_trylock(&lock)){
        printk("down_trylock failed!\n");
        return -EBUSY;
    }
    if(setup_irq(IRQ_TIMER0,&timer_irq)){
        printk("setup_irq failed!\n");
        return -EBUSY;
    }

    for(i=0;i<sizeof(button_irqs)/sizeof(button_irqs[0]);i++) {
        err=request_irq(button_irqs[i].irq,button_interrupt,button_irqs[i].flags,
                button_irqs[i].name,(void*)&(button_irqs[i]));
        if(err)
            break;
    }
    if(err) {
        for(--i;i>=0;i--)
            free_irq(button_irqs[i].irq,(void *)&button_irqs[i].num);
        printk("request_irq error!\n");
        return -1;
    }

    disable_irq(IRQ_EINT0);
    disable_irq(IRQ_EINT1);
    disable_irq(IRQ_EINT2);
    disable_irq(IRQ_EINT4);

    set_irq_type(IRQ_EINT0,IRQ_TYPE_LEVEL_LOW);//key4
    set_irq_type(IRQ_EINT1,IRQ_TYPE_EDGE_RISING);//key1
    set_irq_type(IRQ_EINT2,IRQ_TYPE_EDGE_FALLING);//key3
    //set_irq_type(IRQ_EINT4,IRQ_TYPE_EDGE_BOTH);//key2
    set_irq_type(IRQ_EINT4,IRQ_TYPE_EDGE_FALLING);//key2

    enable_irq(IRQ_EINT0);
    enable_irq(IRQ_EINT1);
    enable_irq(IRQ_EINT2);
    enable_irq(IRQ_EINT4);

    return 0;
}

static int button_close(struct inode *inode,struct file *file)
{
    int i;
    for(i=0;i<sizeof(button_irqs)/sizeof(button_irqs[0]);i++) {
        free_irq(button_irqs[i].irq,(void *)&button_irqs[i]);
    }
    remove_irq(IRQ_TIMER0,&timer_irq);
    up(&lock);
    return 0;
}

static int button_read(struct file *filp,char __user *buff,
                        size_t count,loff_t *offp)
{
    unsigned long err;
    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 int timer_ioctl(struct inode *inode,struct file *file,
                        unsigned int cmd,unsigned long arg)
{
    switch (cmd) {
        case TIMER_IOCTL_SET_FREQ:
            printk("timer_ioctl_set_freq\n");
            if(arg==0)
                return -EINVAL;
            timer_set_freq(arg);
            freq_value = arg;
            break;
        case TIMER_IOCTL_STOP:
            printk("timer_ioctl_stop\n");
            timer_stop();
            break;
    }
    return 0;
}

static struct file_operations button_fops = {
    .owner      = THIS_MODULE,
    .open       = button_open,
    .read       = button_read,
    .release    = button_close,
    .ioctl      = timer_ioctl,
};
static struct miscdevice misc = {
    .minor = MISC_DYNAMIC_MINOR,
    .name  = DEVICE_NAME,
    .fops  = &button_fops,
};
//初始化函数
static int __init button_init(void)
{
    init_MUTEX(&lock);

    /*
    if(register_chrdev(BUTTON_MAJOR,DEVICE_NAME,&button_fops)<0) {
        printk(DEVICE_NAME"can't register major number!\n");
        return -1;
    }
    printk(DEVICE_NAME"register sucess!\n");
    */
    if(misc_register(&misc)<0) {
        printk(DEVICE_NAME"can't register major number!\n");
        return -1;
    }
    printk(DEVICE_NAME"register sucess!\n");

    return 0;
}
static void __exit button_exit(void)
{
    timer_stop();
    //unregister_chrdev(BUTTON_MAJOR,DEVICE_NAME);
    misc_deregister(&misc);
}

module_init(button_init);
module_exit(button_exit);

MODULE_LICENSE("GPL");

/**********************************************************************
                     应用程序部分button_app.c
**********************************************************************/

#include
#include
#include
#include
#define msleep(x) usleep(x*1000);
#define TIMER_IOCTL_SET_FREQ 1
#define TIMER_IOCTL_STOP     0
int main(int argc,char **argv)
{
    int fd;
    int ioarg=500;
    int press_cnt[4]={0};
    if((fd=open("/dev/timer_test",0))<0){
        printf("Can't open /dev/timer_test~!");
        return -1;
    }
    printf("sleep begin...\n");
    ioctl(fd,TIMER_IOCTL_SET_FREQ,ioarg);
    //msleep(70000);
    while(1)
        usleep(11111);
    ioctl(fd,TIMER_IOCTL_STOP);
    printf("sleep end...\n");
    close(fd);
    return 0;

}

/***************************************************************
                        makefile部分
****************************************************************/
ifneq ($(KERNELRELEASE),)
obj-m := button_ker.o
else
KDIR :=/home/kernel/linux-2.6.32.2
all:
    make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-

    arm-linux-gcc button_app.c -o button_app
clean:
    rm -f *.ko *.o *.mod.o *.mod.c *.symvers modul*
endif

写的不错，收藏。
http://blog.csdn.net/chuchuanchuan/article/details/7011041