目录

整编内核

修改Makefile文件

编译内核

生成.ko文件

应用层调用

---

这里使用整个编译内核的方式编译.ko文件。

整编内核

编写一个hrtimer_demo.c的驱动程序源码如下：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>
#include <linux/uaccess.h>

#define DEVICE_NAME "hrtimer"

static struct hrtimer hr_timer;
static ktime_t kt;
static int timer_count = 0;
static int trigger_count = 10;  // 默认触发次数

static enum hrtimer_restart timer_callback(struct hrtimer *timer)
{
    timer_count++;
    printk(KERN_INFO "Timer callback, count: %d\n", timer_count);
    
    if (timer_count >= trigger_count) {
        printk(KERN_INFO "Timer triggered %d times, stopping\n", trigger_count);
        return HRTIMER_NORESTART;
    }
    
    hrtimer_forward_now(timer, kt);
    return HRTIMER_RESTART;
}

static int hrtimer_read(struct file *file, char *buf, size_t count, loff_t *ppos)
{
    char tmp[32];
    int len;
    
    len = snprintf(tmp, sizeof(tmp), "Timer count: %d\n", timer_count);
    if (count >= len) {
        if (copy_to_user(buf, tmp, len) != 0) {
            return -EFAULT;
        }
        return len;
    }
    
    return -EINVAL;
}

static int hrtimer_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    switch (cmd) {
        case 0:  // 停止定时器
            hrtimer_cancel(&hr_timer);
            printk(KERN_INFO "Hrtimer stopped\n");
            break;
        case 1:  // 重启定时器
            hrtimer_start(&hr_timer, kt, HRTIMER_MODE_REL);
            printk(KERN_INFO "Hrtimer restarted\n");
            break;
        case 2:  // 设置触发次数
            if (arg <= 0) {
                return -EINVAL;
            }
            trigger_count = arg;
            printk(KERN_INFO "Trigger count set to %d\n", trigger_count);
            break;
        case 3:  // 设置触发周期
            if (arg <= 0) {
                return -EINVAL;
            }
            kt = ktime_set(arg, 0);
            printk(KERN_INFO "Trigger period set to %ld seconds\n", arg);
            break;
        default:
            return -EINVAL;
    }
    
    return 0;
}

static struct file_operations hrtimer_fops = {
    .read = hrtimer_read,
    .unlocked_ioctl = hrtimer_ioctl,
};

static struct miscdevice hrtimer_miscdev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &hrtimer_fops,
};

static int __init hrtimer_demo_init(void)
{
    int ret;
    
    printk(KERN_INFO "Hrtimer module loaded\n");
    
    // 初始化定时器
    hrtimer_init(&hr_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    
    // 设置定时器的超时时间为1秒
    kt = ktime_set(1, 0);
    
    // 设置定时器的回调函数
    hr_timer.function = timer_callback;
    
    // 启动定时器
    hrtimer_start(&hr_timer, kt, HRTIMER_MODE_REL);
    
    // 注册设备
    ret = misc_register(&hrtimer_miscdev);
    if (ret < 0) {
        printk(KERN_ERR "Failed to register misc device\n");
        return ret;
    }
    
    return 0;
}

static void __exit hrtimer_demo_exit(void)
{
    // 注销设备
    misc_deregister(&hrtimer_miscdev);
    
    // 停止定时器
    hrtimer_cancel(&hr_timer);
    
    printk(KERN_INFO "Hrtimer module unloaded\n");
}

module_init(hrtimer_demo_init);
module_exit(hrtimer_demo_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("Hrtimer Example");

将hrtimer_demo.c程序拷贝到linux-3.10/drivers/char/目录下

 

修改Makefile文件

修改linux-3.10/drivers/char/目录下Makefile文件，在Makefile中增加如下代码： 

obj-m += hrtimer_demo.o

编译内核

lu@Computer:~/workplace/A40i/lichee$ ./build.sh -m kernel

生成.ko文件

 

应用层调用

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>

#define DEVICE_PATH "/dev/hrtimer"

int stop_timer(int fd)
{
    if (ioctl(fd, 0) < 0) {
        perror("Failed to stop timer");
        return -1;
    }

    printf("Timer stopped\n");

    return 0;
}

int restart_timer(int fd)
{
    if (ioctl(fd, 1) < 0) {
        perror("Failed to restart timer");
        return -1;
    }

    printf("Timer restarted\n");

    return 0;
}

int set_trigger_count(int fd, int count)
{
    if (ioctl(fd, 2, count) < 0) {
        perror("Failed to set trigger count");
        return -1;
    }

    printf("Trigger count set to %d\n", count);

    return 0;
}

int set_trigger_period(int fd, int period)
{
    if (ioctl(fd, 3, period) < 0) {
        perror("Failed to set trigger period");
        return -1;
    }

    printf("Trigger period set to %d ms\n", period);

    return 0;
}

int main()
{
    int fd;
    char buf[256];

    // 打开设备文件
    fd = open(DEVICE_PATH, O_RDWR);
    if (fd < 0) {
        perror("Failed to open device");
        return -1;
    }

    // 读取设备文件
    if (read(fd, buf, sizeof(buf)) < 0) {
        perror("Failed to read device");
        close(fd);
        return -1;
    }

    printf("Read from device: %s\n", buf);

    // 停止定时器
    if (stop_timer(fd) < 0) {
        close(fd);
        return -1;
    }

    // 设置触发次数为5
    if (set_trigger_count(fd, 5) < 0) {
        close(fd);
        return -1;
    }

    // 设置触发周期为2毫秒
    if (set_trigger_period(fd, 2) < 0) {
        close(fd);
        return -1;
    }

    // 重启定时器
    if (restart_timer(fd) < 0) {
        close(fd);
        return -1;
    }

    // 关闭设备文件
    close(fd);

    return 0;
}