最简陋的arm定时器1s定时程序

最简陋的arm定时器1s定时程序

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#include //这个头文件里的__REG()宏返回的就是寄存器的虚拟地址，在下面程序里（驱动程序里用的都是虚拟地址，不能用物理地址）
#include
#include
#include

#define KERNEL_DEBUG

#define DEVICE_NAME "mytimer"
#define CB_MAJOR 232

#define TIMER_OUT GPIO_C12    //用一个GPIO口告诉外设定时到
static devfs_handle_t devfs_h;
char timer_out=0;
void initial_timer()
{    int bb;
    //powermanagement MPLL M=0x52,P=2,S=3
    //MPLLCON=0x00052023;//这句在系统启动后似乎不能加上，估计启动后不能重写这个寄存器
    /*   
    bb=MPLLCON;//这里读到的值是5c040,若采用这个值则16和256分频后为48828.125Hz   
    printk("MPLLCO=%x\n",bb);
    */
    //mux=11, 16分频
    TCFG1=0x00000003;
   
    //prescalor=256
    TCFG0=0x000000FF;
   
    TCNTB0=0xBEBC;//48828
    TCMPB0=0xBEBC/2;
   
    bb=TCON;
    TCON=bb|0x2;//set the manual update bit
  
    bb=TCON;
    TCON=bb|0x4;//set the inverter bit
    //start timer0
    bb=(bb&0xD)|0x9;//reset manual update bit,set the start bit and reload bit
    TCON=bb;
}
//以下几个接口都是空壳
static ssize_t timer_read(struct file *file,char *buffer,size_t count,loff_t *ppos)
{    return 0;
}

static ssize_t timer_write(struct file *file, const char *buffer, size_t count)
{
    return 0;
}

static int timer_ioctl(struct inode *inode, struct file *file ,unsigned int cmd, unsigned long arg)
{
    return 0;
}
//发生中断时执行此函数
static void timer_irq(int irq,void *dev_id,struct pt_regs *reg)
{
    int found=0;
    printk("into the ISR\n");
    if(irq==IRQ_TIMER0)
    {    printk("time out irq%d",irq);
        found=1;
    }
    if(!found)
    {
        printk("Bad irq%d",irq);
        return;
    }
    if(timer_out==0)
    {    timer_out=1;
        write_gpio_bit(TIMER_OUT,0);
    }
    else
    {    timer_out=0;
        write_gpio_bit(TIMER_OUT,1);
    }
}

static struct file_operations timer_fops={
    owner: THIS_MODULE,
    write: timer_write,
    //poll:     timer_select,
    read: timer_read,
    ioctl: timer_ioctl,   
};

//整个驱动的初始化入口
static int __init timer_init(void)
{
    int ret;
    ret=register_chrdev(CB_MAJOR,DEVICE_NAME,&timer_fops);
    printk("get to timer!\n");
    set_gpio_ctrl(GPIO_MODE_OUT|GPIO_PULLUP_EN|TIMER_OUT);
    write_gpio_bit(TIMER_OUT,1);
   
    initial_timer();
    printk("after initial_timer()\n");
    if(ret<0)
    {
        printk(DEVICE_NAME" can't register major number\n");
        return ret;
    }
    //关联中断和中断函数
    if(request_irq(IRQ_TIMER0,&timer_irq,SA_INTERRUPT,DEVICE_NAME,&timer_irq))
    {
        printk(DEVICE_NAME "can't request irqs\n");
        return -1;
    }
  //关联设备和fops结构   
 devfs_h=devfs_register(NULL,DEVICE_NAME,DEVFS_FL_DEFAULT,CB_MAJOR,0,S_IFCHR|S_IRUSR|S_IWUSR,&timer_fops,NULL);
    return 0;
}

static void __exit timer_exit(void)
{
    devfs_unregister(devfs_h);
    free_irq(IRQ_TIMER0,timer_irq);
    unregister_chrdev(CB_MAJOR, DEVICE_NAME);
}
module_init(timer_init);
module_exit(timer_exit);

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/sergeycao/archive/2008/09/18/2945133.aspx