最简陋的arm定时器1s定时程序

#include <linux/version.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <asm/system.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/delay.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <asm/arch/hardware.h>//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 <asm/delay.h>
#include <asm/arch/irqs.h>
#include <asm/arch/S3C2410.h>

#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);

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最简陋的arm定时器1s定时程序

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