rtc.c

powerpc内核mpc8241linux系统下char驱动程序

		CMOS_WRITE(val, RTC_FREQ_SELECT);
		restore_flags(flags);
		return 0;
	}
#ifdef __alpha__
	case RTC_EPOCH_READ:	/* Read the epoch.	*/
	{
		return put_user (epoch, (unsigned long *)arg);
	}
	case RTC_EPOCH_SET:	/* Set the epoch.	*/
	{
		/* 
		 * There were no RTC clocks before 1900.
		 */
		if (arg < 1900)
			return -EINVAL;

		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		epoch = arg;
		return 0;
	}
#endif
	default:
		return -EINVAL;
	}
	return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
}

/*
 *	We enforce only one user at a time here with the open/close.
 *	Also clear the previous interrupt data on an open, and clean
 *	up things on a close.
 */

static int rtc_open(struct inode *inode, struct file *file)
{
	if(rtc_status & RTC_IS_OPEN)
		return -EBUSY;

	rtc_status |= RTC_IS_OPEN;
	rtc_irq_data = 0;
	return 0;
}

static int rtc_release(struct inode *inode, struct file *file)
{
	/*
	 * Turn off all interrupts once the device is no longer
	 * in use, and clear the data.
	 */

	unsigned char tmp;
	unsigned long flags;

	save_flags(flags);
	cli();
	tmp = CMOS_READ(RTC_CONTROL);
	tmp &=  ~RTC_PIE;
	tmp &=  ~RTC_AIE;
	tmp &=  ~RTC_UIE;
	CMOS_WRITE(tmp, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);
	restore_flags(flags);

	if (rtc_status & RTC_TIMER_ON) {
		rtc_status &= ~RTC_TIMER_ON;
		del_timer(&rtc_irq_timer);
	}

	rtc_irq_data = 0;
	rtc_status &= ~RTC_IS_OPEN;
	return 0;
}

static unsigned int rtc_poll(struct file *file, poll_table *wait)
{
	poll_wait(file, &rtc_wait, wait);
	if (rtc_irq_data != 0)
		return POLLIN | POLLRDNORM;
	return 0;
}

/*
 *	The various file operations we support.
 */

static struct file_operations rtc_fops = {
	rtc_llseek,
	rtc_read,
	NULL,		/* No write */
	NULL,		/* No readdir */
	rtc_poll,
	rtc_ioctl,
	NULL,		/* No mmap */
	rtc_open,
	NULL,		/* flush */
	rtc_release
};

static struct miscdevice rtc_dev=
{
	RTC_MINOR,
	"rtc",
	&rtc_fops
};

__initfunc(int rtc_init(void))
{
	unsigned long flags;
#ifdef __alpha__
	unsigned int year, ctrl;
	unsigned long uip_watchdog;
	char *guess = NULL;
#endif
	printk(KERN_INFO "Real Time Clock Driver v%s\n", RTC_VERSION);
	if(request_irq(RTC_IRQ, rtc_interrupt, SA_INTERRUPT, "rtc", NULL))
	{
		/* Yeah right, seeing as irq 8 doesn't even hit the bus. */
		printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
		return -EIO;
	}
	misc_register(&rtc_dev);
	/* Check region? Naaah! Just snarf it up. */
	request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
#ifdef __alpha__
	rtc_freq = HZ;
	
	/* Each operating system on an Alpha uses its own epoch.
	   Let's try to guess which one we are using now. */
	
	uip_watchdog = jiffies;
	if (rtc_is_updating() != 0)
		while (jiffies - uip_watchdog < 2*HZ/100)
			barrier();
	
	save_flags(flags);
	cli();
	year = CMOS_READ(RTC_YEAR);
	ctrl = CMOS_READ(RTC_CONTROL);
	restore_flags(flags);
	
	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
		BCD_TO_BIN(year);       /* This should never happen... */
	
	if (year > 10 && year < 44) {
		epoch = 1980;
		guess = "ARC console";
	} else if (year < 96) {
		epoch = 1952;
		guess = "Digital UNIX";
	}
	if (guess)
		printk("rtc: %s epoch (%lu) detected\n", guess, epoch);
#endif
	init_timer(&rtc_irq_timer);
	rtc_irq_timer.function = rtc_dropped_irq;
	rtc_wait = NULL;
	save_flags(flags);
	cli();
	/* Initialize periodic freq. to CMOS reset default, which is 1024Hz */
	CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06), RTC_FREQ_SELECT);
	restore_flags(flags);
	rtc_freq = 1024;
	return 0;
}

/*
 * 	At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
 *	(usually during an IDE disk interrupt, with IRQ unmasking off)
 *	Since the interrupt handler doesn't get called, the IRQ status
 *	byte doesn't get read, and the RTC stops generating interrupts.
 *	A timer is set, and will call this function if/when that happens.
 *	To get it out of this stalled state, we just read the status.
 *	At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
 *	(You *really* shouldn't be trying to use a non-realtime system 
 *	for something that requires a steady > 1KHz signal anyways.)
 */

void rtc_dropped_irq(unsigned long data)
{
	unsigned long flags;

	printk(KERN_INFO "rtc: lost some interrupts at %ldHz.\n", rtc_freq);
	mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);

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

/*
 *	Info exported via "/proc/rtc".
 */

int get_rtc_status(char *buf)
{
	char *p;
	struct rtc_time tm;
	unsigned char batt, ctrl;
	unsigned long flags;

	save_flags(flags);
	cli();
	batt = CMOS_READ(RTC_VALID) & RTC_VRT;
	ctrl = CMOS_READ(RTC_CONTROL);
	restore_flags(flags);

	p = buf;

	get_rtc_time(&tm);

	/*
	 * There is no way to tell if the luser has the RTC set for local
	 * time or for Universal Standard Time (GMT). Probably local though.
	 */
	p += sprintf(p,
		     "rtc_time\t: %02d:%02d:%02d\n"
		     "rtc_date\t: %04d-%02d-%02d\n"
	 	     "rtc_epoch\t: %04lu\n",
		     tm.tm_hour, tm.tm_min, tm.tm_sec,
		     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);

	get_rtc_alm_time(&tm);

	/*
	 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
	 * match any value for that particular field. Values that are
	 * greater than a valid time, but less than 0xc0 shouldn't appear.
	 */
	p += sprintf(p, "alarm\t\t: ");
	if (tm.tm_hour <= 24)
		p += sprintf(p, "%02d:", tm.tm_hour);
	else
		p += sprintf(p, "**:");

	if (tm.tm_min <= 59)
		p += sprintf(p, "%02d:", tm.tm_min);
	else
		p += sprintf(p, "**:");

	if (tm.tm_sec <= 59)
		p += sprintf(p, "%02d\n", tm.tm_sec);
	else
		p += sprintf(p, "**\n");

	p += sprintf(p,
		     "DST_enable\t: %s\n"
		     "BCD\t\t: %s\n"
		     "24hr\t\t: %s\n"
		     "square_wave\t: %s\n"
		     "alarm_IRQ\t: %s\n"
		     "update_IRQ\t: %s\n"
		     "periodic_IRQ\t: %s\n"
		     "periodic_freq\t: %ld\n"
		     "batt_status\t: %s\n",
		     (ctrl & RTC_DST_EN) ? "yes" : "no",
		     (ctrl & RTC_DM_BINARY) ? "no" : "yes",
		     (ctrl & RTC_24H) ? "yes" : "no",
		     (ctrl & RTC_SQWE) ? "yes" : "no",
		     (ctrl & RTC_AIE) ? "yes" : "no",
		     (ctrl & RTC_UIE) ? "yes" : "no",
		     (ctrl & RTC_PIE) ? "yes" : "no",
		     rtc_freq,
		     batt ? "okay" : "dead");

	return  p - buf;
}

/*
 * Returns true if a clock update is in progress
 */
static inline unsigned char rtc_is_updating(void)
{
	unsigned long flags;
	unsigned char uip;

	save_flags(flags);
	cli();
	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
	restore_flags(flags);
	return uip;
}

void get_rtc_time(struct rtc_time *rtc_tm)
{

	unsigned long flags, uip_watchdog = jiffies;
	unsigned char ctrl;

	/*
	 * read RTC once any update in progress is done. The update
	 * can take just over 2ms. We wait 10 to 20ms. There is no need to
	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
	 * If you need to know *exactly* when a second has started, enable
	 * periodic update complete interrupts, (via ioctl) and then 
	 * immediately read /dev/rtc which will block until you get the IRQ.
	 * Once the read clears, read the RTC time (again via ioctl). Easy.
	 */

	if (rtc_is_updating() != 0)
		while (jiffies - uip_watchdog < 2*HZ/100)
			barrier();

	/*
	 * Only the values that we read from the RTC are set. We leave
	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
	 * by the RTC when initially set to a non-zero value.
	 */
	save_flags(flags);
	cli();
	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
	rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
	rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
	rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
	rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
	rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
	ctrl = CMOS_READ(RTC_CONTROL);
	restore_flags(flags);

	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
	{
		BCD_TO_BIN(rtc_tm->tm_sec);
		BCD_TO_BIN(rtc_tm->tm_min);
		BCD_TO_BIN(rtc_tm->tm_hour);
		BCD_TO_BIN(rtc_tm->tm_mday);
		BCD_TO_BIN(rtc_tm->tm_mon);
		BCD_TO_BIN(rtc_tm->tm_year);
	}


	/*
	 * Account for differences between how the RTC uses the values
	 * and how they are defined in a struct rtc_time;
	 */
	if ((rtc_tm->tm_year += (epoch - 1900)) <= 69)
		rtc_tm->tm_year += 100;

	rtc_tm->tm_mon--;
}

void get_rtc_alm_time(struct rtc_time *alm_tm)
{
	unsigned long flags;
	unsigned char ctrl;

	/*
	 * Only the values that we read from the RTC are set. That
	 * means only tm_hour, tm_min, and tm_sec.
	 */
	save_flags(flags);
	cli();
	alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
	alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
	alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
	ctrl = CMOS_READ(RTC_CONTROL);
	restore_flags(flags);

	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
	{
		BCD_TO_BIN(alm_tm->tm_sec);
		BCD_TO_BIN(alm_tm->tm_min);
		BCD_TO_BIN(alm_tm->tm_hour);
	}
}

/*
 * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
 * Rumour has it that if you frob the interrupt enable/disable
 * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
 * ensure you actually start getting interrupts. Probably for
 * compatibility with older/broken chipset RTC implementations.
 * We also clear out any old irq data after an ioctl() that
 * meddles with the interrupt enable/disable bits.
 */

void mask_rtc_irq_bit(unsigned char bit)
{
	unsigned char val;
	unsigned long flags;

	save_flags(flags);
	cli();
	val = CMOS_READ(RTC_CONTROL);
	val &=  ~bit;
	CMOS_WRITE(val, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);
	restore_flags(flags);
	rtc_irq_data = 0;
}

void set_rtc_irq_bit(unsigned char bit)
{
	unsigned char val;
	unsigned long flags;

	save_flags(flags);
	cli();
	val = CMOS_READ(RTC_CONTROL);
	val |= bit;
	CMOS_WRITE(val, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);
	rtc_irq_data = 0;
	restore_flags(flags);
}