static void rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
　/*
　* Can be an alarm interrupt, update complete interrupt,
　* or a periodic interrupt. We store the status in the
　* low byte and the number of interrupts received since
　* the last read in the remainder of rtc_irq_data.
　*/

　spin_lock(&rtc_lock);
　rtc_irq_data += 0x100;
　rtc_irq_data &= ~0xff;
　rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) &0xF0);

　if (rtc_status &RTC_TIMER_ON)
　　mod_timer(&rtc_irq_timer, jiffies + HZ / rtc_freq + 2 * HZ / 100);

　spin_unlock(&rtc_lock);

　/* Now do the rest of the actions */
　wake_up_interruptible(&rtc_wait);

　kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
}

static int rtc_fasync (int fd, struct file *filp, int on)
{
　return fasync_helper (fd, filp, on, &rtc_async_queue);
}

static void rtc_dropped_irq(unsigned long data)
{
　unsigned long freq;

　spin_lock_irq(&rtc_lock);

　/* Just in case someone disabled the timer from behind our back... */
　if (rtc_status &RTC_TIMER_ON)
　　mod_timer(&rtc_irq_timer, jiffies + HZ / rtc_freq + 2 * HZ / 100);

　rtc_irq_data += ((rtc_freq / HZ) << 8);
　rtc_irq_data &= ~0xff;
　rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) &0xF0); /* restart */

　freq = rtc_freq;

　spin_unlock_irq(&rtc_lock);
　printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n", freq);

　/* Now we have new data */
　wake_up_interruptible(&rtc_wait);

　kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
}