rtc.c

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		goto out_busy;

	rtc_status |= RTC_IS_OPEN;

	rtc_irq_data = 0;
	spin_unlock_irq (&rtc_lock);
	return 0;

out_busy:
	spin_unlock_irq (&rtc_lock);
	return -EBUSY;
}

static int rtc_fasync (int fd, struct file *filp, int on)

{
	return fasync_helper (fd, filp, on, &rtc_async_queue);
}

static int rtc_release(struct inode *inode, struct file *file)
{
#if RTC_IRQ
	unsigned char tmp;

	if (rtc_has_irq == 0)
		goto no_irq;

	/*
	 * Turn off all interrupts once the device is no longer
	 * in use, and clear the data.
	 */

	spin_lock_irq(&rtc_lock);
	tmp = CMOS_READ(RTC_CONTROL);
	tmp &=  ~RTC_PIE;
	tmp &=  ~RTC_AIE;
	tmp &=  ~RTC_UIE;
	CMOS_WRITE(tmp, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);

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

	if (file->f_flags & FASYNC) {
		rtc_fasync (-1, file, 0);
	}
no_irq:
#endif

	spin_lock_irq (&rtc_lock);
	rtc_irq_data = 0;
	spin_unlock_irq (&rtc_lock);

	/* No need for locking -- nobody else can do anything until this rmw is
	 * committed, and no timer is running. */
	rtc_status &= ~RTC_IS_OPEN;
	return 0;
}

#if RTC_IRQ
/* Called without the kernel lock - fine */
static unsigned int rtc_poll(struct file *file, poll_table *wait)
{
	unsigned long l;

	if (rtc_has_irq == 0)
		return 0;

	poll_wait(file, &rtc_wait, wait);

	spin_lock_irq (&rtc_lock);
	l = rtc_irq_data;
	spin_unlock_irq (&rtc_lock);

	if (l != 0)
		return POLLIN | POLLRDNORM;
	return 0;
}
#endif

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

static struct file_operations rtc_fops = {
	owner:		THIS_MODULE,
	llseek:		no_llseek,
	read:		rtc_read,
#if RTC_IRQ
	poll:		rtc_poll,
#endif
	ioctl:		rtc_ioctl,
	open:		rtc_open,
	release:	rtc_release,
	fasync:		rtc_fasync,
};

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

static int __init rtc_init(void)
{
#if defined(__alpha__) || defined(__mips__)
	unsigned int year, ctrl;
	unsigned long uip_watchdog;
	char *guess = NULL;
#endif
#ifdef __sparc__
	struct linux_ebus *ebus;
	struct linux_ebus_device *edev;
#ifdef __sparc_v9__
	struct isa_bridge *isa_br;
	struct isa_device *isa_dev;
#endif
#endif

#ifdef __sparc__
	for_each_ebus(ebus) {
		for_each_ebusdev(edev, ebus) {
			if(strcmp(edev->prom_name, "rtc") == 0) {
				rtc_port = edev->resource[0].start;
				rtc_irq = edev->irqs[0];
				goto found;
			}
		}
	}
#ifdef __sparc_v9__
	for_each_isa(isa_br) {
		for_each_isadev(isa_dev, isa_br) {
			if (strcmp(isa_dev->prom_name, "rtc") == 0) {
				rtc_port = isa_dev->resource.start;
				rtc_irq = isa_dev->irq;
				goto found;
			}
		}
	}
#endif
	printk(KERN_ERR "rtc_init: no PC rtc found\n");
	return -EIO;

found:
	if (rtc_irq == PCI_IRQ_NONE) {
		rtc_has_irq = 0;
		goto no_irq;
	}

	/*
	 * XXX Interrupt pin #7 in Espresso is shared between RTC and
	 * PCI Slot 2 INTA# (and some INTx# in Slot 1). SA_INTERRUPT here
	 * is asking for trouble with add-on boards. Change to SA_SHIRQ.
	 */
	if (request_irq(rtc_irq, rtc_interrupt, SA_INTERRUPT, "rtc", (void *)&rtc_port)) {
		/*
		 * Standard way for sparc to print irq's is to use
		 * __irq_itoa(). I think for EBus it's ok to use %d.
		 */
		printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
		return -EIO;
	}
no_irq:
#else
	if (check_region (RTC_PORT (0), RTC_IO_EXTENT))
	{
		printk(KERN_ERR "rtc: I/O port %d is not free.\n", RTC_PORT (0));
		return -EIO;
	}

#if RTC_IRQ
	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;
	}
#endif

	request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
#endif /* __sparc__ vs. others */

	misc_register(&rtc_dev);
	create_proc_read_entry ("driver/rtc", 0, 0, rtc_read_proc, NULL);

#if defined(__alpha__) || defined(__mips__)
	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();
			cpu_relax();
		}
	
	spin_lock_irq(&rtc_lock);
	year = CMOS_READ(RTC_YEAR);
	ctrl = CMOS_READ(RTC_CONTROL);
	spin_unlock_irq(&rtc_lock);
	
	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
		BCD_TO_BIN(year);       /* This should never happen... */
	
	if (year < 20) {
		epoch = 2000;
		guess = "SRM (post-2000)";
	} else if (year >= 20 && year < 48) {
		epoch = 1980;
		guess = "ARC console";
	} else if (year >= 48 && year < 72) {
		epoch = 1952;
		guess = "Digital UNIX";
#if defined(__mips__)
	} else if (year >= 72 && year < 74) {
		epoch = 2000;
		guess = "Digital DECstation";
#else
	} else if (year >= 70) {
		epoch = 1900;
		guess = "Standard PC (1900)";
#endif
	}
	if (guess)
		printk(KERN_INFO "rtc: %s epoch (%lu) detected\n", guess, epoch);
#endif
#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);

#ifdef __sparc__
	if (rtc_has_irq)
		free_irq (rtc_irq, &rtc_port);
#else
	release_region (RTC_PORT (0), RTC_IO_EXTENT);
#if RTC_IRQ
	if (rtc_has_irq)
		free_irq (RTC_IRQ, NULL);
#endif
#endif /* __sparc__ */
}

module_init(rtc_init);
module_exit(rtc_exit);
EXPORT_NO_SYMBOLS;

#if RTC_IRQ
/*
 * 	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.)
 */

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);
}
#endif

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

static int rtc_proc_output (char *buf)
{
#define YN(bit) ((ctrl & bit) ? "yes" : "no")
#define NY(bit) ((ctrl & bit) ? "no" : "yes")
	char *p;
	struct rtc_time tm;
	unsigned char batt, ctrl;
	unsigned long freq;

	spin_lock_irq(&rtc_lock);
	batt = CMOS_READ(RTC_VALID) & RTC_VRT;
	ctrl = CMOS_READ(RTC_CONTROL);
	freq = rtc_freq;
	spin_unlock_irq(&rtc_lock);

	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",
		     YN(RTC_DST_EN),
		     NY(RTC_DM_BINARY),
		     YN(RTC_24H),
		     YN(RTC_SQWE),
		     YN(RTC_AIE),
		     YN(RTC_UIE),
		     YN(RTC_PIE),
		     freq,
		     batt ? "okay" : "dead");

	return  p - buf;
#undef YN
#undef NY
}

static int rtc_read_proc(char *page, char **start, off_t off,
                         int count, int *eof, void *data)
{
        int len = rtc_proc_output (page);
        if (len <= off+count) *eof = 1;
        *start = page + off;
        len -= off;
        if (len>count) len = count;
        if (len<0) len = 0;
        return len;
}

/*
 * Returns true if a clock update is in progress
 */
/* FIXME shouldn't this be above rtc_init to make it fully inlined? */
static inline unsigned char rtc_is_updating(void)
{
	unsigned char uip;

	spin_lock_irq(&rtc_lock);
	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
	spin_unlock_irq(&rtc_lock);
	return uip;
}

static void get_rtc_time(struct rtc_time *rtc_tm)
{
	unsigned long uip_watchdog = jiffies;
	unsigned char ctrl;
#ifdef CONFIG_DECSTATION
	unsigned int real_year;
#endif

	/*
	 * 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();
			cpu_relax();
		}

	/*
	 * 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.
	 */
	spin_lock_irq(&rtc_lock);
	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);
#ifdef CONFIG_DECSTATION
	real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
	ctrl = CMOS_READ(RTC_CONTROL);
	spin_unlock_irq(&rtc_lock);

	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);
	}

#ifdef CONFIG_DECSTATION
	rtc_tm->tm_year += real_year - 72;
#endif

	/*
	 * 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--;
}

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

	/*
	 * Only the values that we read from the RTC are set. That
	 * means only tm_hour, tm_min, and tm_sec.
	 */
	spin_lock_irq(&rtc_lock);
	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);
	spin_unlock_irq(&rtc_lock);

	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);
	}
}

#if RTC_IRQ
/*
 * 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.
 */

static void mask_rtc_irq_bit(unsigned char bit)
{
	unsigned char val;

	spin_lock_irq(&rtc_lock);
	val = CMOS_READ(RTC_CONTROL);
	val &=  ~bit;
	CMOS_WRITE(val, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);

	rtc_irq_data = 0;
	spin_unlock_irq(&rtc_lock);
}

static void set_rtc_irq_bit(unsigned char bit)
{
	unsigned char val;

	spin_lock_irq(&rtc_lock);
	val = CMOS_READ(RTC_CONTROL);
	val |= bit;
	CMOS_WRITE(val, RTC_CONTROL);
	CMOS_READ(RTC_INTR_FLAGS);

	rtc_irq_data = 0;
	spin_unlock_irq(&rtc_lock);
}
#endif

MODULE_AUTHOR("Paul Gortmaker");
MODULE_LICENSE("GPL");