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);

5 例子代码

#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");

6 测试结果