深入浅出Linux设备驱动中断处理介绍

int request_irq(unsigned int irq,
void (*handler)(int irq, void *dev_id, struct pt_regs *regs),
unsigned long irqflags,
const char * devname,
                        void *dev_id);

static struct fasync_struct *rtc_async_queue;
static int __init rtc_init(void)
{
　misc_register(&rtc_dev);
　create_proc_read_entry("driver/rtc", 0, 0, rtc_read_proc, NULL);
　#if RTC_IRQ
　　if (rtc_has_irq == 0)
　　　goto no_irq2;
　　init_timer(&rtc_irq_timer);
　　rtc_irq_timer.function = rtc_dropped_irq;
　　spin_lock_irq(&rtc_lock);
　　/* Initialize periodic freq. to CMOS reset default, which is 1024Hz */
　　CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) &0xF0) | 0x06), RTC_FREQ_SELECT);
　　spin_unlock_irq(&rtc_lock);
　　rtc_freq = 1024;
　　no_irq2:
　#endif
　printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
　return 0;
}
static void __exit rtc_exit(void)
{
　remove_proc_entry("driver/rtc", NULL);
　misc_deregister(&rtc_dev);
　release_region(RTC_PORT(0), RTC_IO_EXTENT);
　if (rtc_has_irq)
　　free_irq(RTC_IRQ, NULL);
}
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);
                        }