hrtimer和work工作队列的使用

1.hrtimers - 为高分辨率kernel定时器，可作为超时或周期性定时器使用

1). hrtimer_init初始化定时器工作模式。

 hrtimer_init(&vibe_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 vibe_timer.function = vibrator_timer_func;

 /* 设置定时器的回调函数，定时器到时该函数将被调用 */

 static enum hrtimer_restart vibrator_timer_func(struct hrtimer *timer)

 注：该回调函数为原子操作不能被中断

2). hrtimer_start的第二个参数用于设置超时参数。
  hrtimer_start(&vibe_timer,
  ktime_set(value / 1000, (value % 1000) * 1000000),HRTIMER_MODE_REL);

3). INIT_WORK初始化工作队列。

  INIT_WORK(&vibe_work, vibe_work_func);

  static void vibe_work_func(struct work_struct *work)

4). schedule_work调用工作队列。

  schedule_work(&vibe_work);

/* linux/drivers/ker-driver.c
 * Author: Woodpecker <Pecker.hu@gmail.com>
 *
 * kernel-driver
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive for
 * more details.
 *
 */

#include <linux/module.h>     /* MODULE_LICENSE     */
#include <linux/kernel.h>     /* printk,pr_info     */
#include <linux/errno.h>      /* EINVAL,EAGAIN,etc. */
#include <linux/err.h>            /* IS_ERR             */
#include <linux/fb.h>         /* FB header file     */
#include <linux/init.h>           /* module_init        */
#include <linux/semaphore.h>  /* init_MUTEX APIs    */
#include <linux/mm.h>         /* vm_area_struct     */
#include <linux/dma-mapping.h>  /* DMA APIs             */
#include <linux/delay.h>      /* mdelay,msleep      */
#include <linux/hrtimer.h>
#include <linux/time.h>           /* struct timespec    */

#define KER_PRINT(fmt, ...) printk("<ker-driver>"fmt, ##__VA_ARGS__);
static struct hrtimer vibe_timer;
static struct work_struct vibe_work;

static void vibe_work_func(struct work_struct *work)
{
    KER_PRINT("vibe_work_func:msleep(50)/n");
    msleep(50); /* CPU sleep */
}

static enum hrtimer_restart vibrator_timer_func(struct hrtimer *timer)
{
    struct timespec uptime;

    do_posix_clock_monotonic_gettime(&uptime);
    KER_PRINT("Time:%lu.%02lu/n",
            (unsigned long) uptime.tv_sec,
            (uptime.tv_nsec / (NSEC_PER_SEC / 100)));

    KER_PRINT("vibrator_timer_func/n");
    schedule_work(&vibe_work);
    return HRTIMER_NORESTART;
}

static int __init ker_driver_init(void)
{

    int value = 2000;   /* Time out setting,2 seconds */
    struct timespec uptime;

    KER_PRINT("ker_driver_init/n");
    hrtimer_init(&vibe_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    vibe_timer.function = vibrator_timer_func;
    hrtimer_start(&vibe_timer,
        ktime_set(value / 1000, (value % 1000) * 1000000),HRTIMER_MODE_REL);

      //static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)  第一个参数为秒，第二个为纳秒

    do_posix_clock_monotonic_gettime(&uptime);
    KER_PRINT("Time:%lu.%02lu/n",
            (unsigned long) uptime.tv_sec,
            (uptime.tv_nsec / (NSEC_PER_SEC / 100)));

    INIT_WORK(&vibe_work, vibe_work_func);  /* Intialize the work queue */
    return 0;

}

static void __exit ker_driver_exit(void)
{
    hrtimer_cancel(&vibe_timer);
}

module_init(ker_driver_init);
module_exit(ker_driver_exit);

MODULE_AUTHOR("Woodpecker <Pecker.hu@gmail.com>");
MODULE_DESCRIPTION("Kernel driver");
MODULE_LICENSE("GPL");

驱动的运行结果：