drivers/rtc/rtc-bfin.c - kernel/msm-4.9 - Gitiles

 /*
  * Blackfin On-Chip Real Time Clock Driver
  *  Supports BF53[123]/BF53[467]/BF54[2489]
  *
  * Copyright 2004-2007 Analog Devices Inc.
  *
  * Enter bugs at http://blackfin.uclinux.org/
  *
  * Licensed under the GPL-2 or later.
  */

 /* The biggest issue we deal with in this driver is that register writes are
  * synced to the RTC frequency of 1Hz.  So if you write to a register and
  * attempt to write again before the first write has completed, the new write
  * is simply discarded.  This can easily be troublesome if userspace disables
  * one event (say periodic) and then right after enables an event (say alarm).
  * Since all events are maintained in the same interrupt mask register, if
  * we wrote to it to disable the first event and then wrote to it again to
  * enable the second event, that second event would not be enabled as the
  * write would be discarded and things quickly fall apart.
  *
  * To keep this delay from significantly degrading performance (we, in theory,
  * would have to sleep for up to 1 second everytime we wanted to write a
  * register), we only check the write pending status before we start to issue
  * a new write.  We bank on the idea that it doesnt matter when the sync
  * happens so long as we don't attempt another write before it does.  The only
  * time userspace would take this penalty is when they try and do multiple
  * operations right after another ... but in this case, they need to take the
  * sync penalty, so we should be OK.
  *
  * Also note that the RTC_ISTAT register does not suffer this penalty; its
  * writes to clear status registers complete immediately.
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/bcd.h>
 #include <linux/rtc.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/delay.h>

 #include <asm/blackfin.h>

 #define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __FUNCTION__, __LINE__, ## args)
 #define stampit() stamp("here i am")

 struct bfin_rtc {
 	struct rtc_device *rtc_dev;
 	struct rtc_time rtc_alarm;
 	spinlock_t lock;
 };

 /* Bit values for the ISTAT / ICTL registers */
 #define RTC_ISTAT_WRITE_COMPLETE  0x8000
 #define RTC_ISTAT_WRITE_PENDING   0x4000
 #define RTC_ISTAT_ALARM_DAY       0x0040
 #define RTC_ISTAT_24HR            0x0020
 #define RTC_ISTAT_HOUR            0x0010
 #define RTC_ISTAT_MIN             0x0008
 #define RTC_ISTAT_SEC             0x0004
 #define RTC_ISTAT_ALARM           0x0002
 #define RTC_ISTAT_STOPWATCH       0x0001

 /* Shift values for RTC_STAT register */
 #define DAY_BITS_OFF    17
 #define HOUR_BITS_OFF   12
 #define MIN_BITS_OFF    6
 #define SEC_BITS_OFF    0

 /* Some helper functions to convert between the common RTC notion of time
  * and the internal Blackfin notion that is stored in 32bits.
  */
 static inline u32 rtc_time_to_bfin(unsigned long now)
 {
 	u32 sec  = (now % 60);
 	u32 min  = (now % (60 * 60)) / 60;
 	u32 hour = (now % (60 * 60 * 24)) / (60 * 60);
 	u32 days = (now / (60 * 60 * 24));
 	return (sec  << SEC_BITS_OFF) +
 	       (min  << MIN_BITS_OFF) +
 	       (hour << HOUR_BITS_OFF) +
 	       (days << DAY_BITS_OFF);
 }
 static inline unsigned long rtc_bfin_to_time(u32 rtc_bfin)
 {
 	return (((rtc_bfin >> SEC_BITS_OFF)  & 0x003F)) +
 	       (((rtc_bfin >> MIN_BITS_OFF)  & 0x003F) * 60) +
 	       (((rtc_bfin >> HOUR_BITS_OFF) & 0x001F) * 60 * 60) +
 	       (((rtc_bfin >> DAY_BITS_OFF)  & 0x7FFF) * 60 * 60 * 24);
 }
 static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm)
 {
 	rtc_time_to_tm(rtc_bfin_to_time(rtc_bfin), tm);
 }

 /* Wait for the previous write to a RTC register to complete.
  * Unfortunately, we can't sleep here as that introduces a race condition when
  * turning on interrupt events.  Consider this:
  *  - process sets alarm
  *  - process enables alarm
  *  - process sleeps while waiting for rtc write to sync
  *  - interrupt fires while process is sleeping
  *  - interrupt acks the event by writing to ISTAT
  *  - interrupt sets the WRITE PENDING bit
  *  - interrupt handler finishes
  *  - process wakes up, sees WRITE PENDING bit set, goes to sleep
  *  - interrupt fires while process is sleeping
  * If anyone can point out the obvious solution here, i'm listening :).  This
  * shouldn't be an issue on an SMP or preempt system as this function should
  * only be called with the rtc lock held.
  */
 static void rtc_bfin_sync_pending(void)
 {
 	stampit();
 	while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE)) {
 		if (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING))
 			break;
 	}
 	bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
 }

 static void rtc_bfin_reset(struct bfin_rtc *rtc)
 {
 	/* Initialize the RTC. Enable pre-scaler to scale RTC clock
 	 * to 1Hz and clear interrupt/status registers. */
 	spin_lock_irq(&rtc->lock);
 	rtc_bfin_sync_pending();
 	bfin_write_RTC_PREN(0x1);
 	bfin_write_RTC_ICTL(0);
 	bfin_write_RTC_SWCNT(0);
 	bfin_write_RTC_ALARM(0);
 	bfin_write_RTC_ISTAT(0xFFFF);
 	spin_unlock_irq(&rtc->lock);
 }

 static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = to_platform_device(dev_id);
 	struct bfin_rtc *rtc = platform_get_drvdata(pdev);
 	unsigned long events = 0;
 	u16 rtc_istat;

 	stampit();

 	spin_lock_irq(&rtc->lock);

 	rtc_istat = bfin_read_RTC_ISTAT();

 	if (rtc_istat & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) {
 		bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY);
 		events |= RTC_AF | RTC_IRQF;
 	}

 	if (rtc_istat & RTC_ISTAT_STOPWATCH) {
 		bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
 		events |= RTC_PF | RTC_IRQF;
 		bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
 	}

 	if (rtc_istat & RTC_ISTAT_SEC) {
 		bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
 		events |= RTC_UF | RTC_IRQF;
 	}

 	rtc_update_irq(rtc->rtc_dev, 1, events);

 	spin_unlock_irq(&rtc->lock);

 	return IRQ_HANDLED;
 }

 static int bfin_rtc_open(struct device *dev)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	int ret;

 	stampit();

 	ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_DISABLED, "rtc-bfin", dev);
 	if (unlikely(ret)) {
 		dev_err(dev, "request RTC IRQ failed with %d\n", ret);
 		return ret;
 	}

 	rtc_bfin_reset(rtc);

 	return ret;
 }

 static void bfin_rtc_release(struct device *dev)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	stampit();
 	rtc_bfin_reset(rtc);
 	free_irq(IRQ_RTC, dev);
 }

 static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);

 	stampit();

 	switch (cmd) {
 	case RTC_PIE_ON:
 		stampit();
 		spin_lock_irq(&rtc->lock);
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
 		bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
 		bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_STOPWATCH);
 		spin_unlock_irq(&rtc->lock);
 		return 0;
 	case RTC_PIE_OFF:
 		stampit();
 		spin_lock_irq(&rtc->lock);
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_SWCNT(0);
 		bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_STOPWATCH);
 		spin_unlock_irq(&rtc->lock);
 		return 0;

 	case RTC_UIE_ON:
 		stampit();
 		spin_lock_irq(&rtc->lock);
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
 		bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | RTC_ISTAT_SEC);
 		spin_unlock_irq(&rtc->lock);
 		return 0;
 	case RTC_UIE_OFF:
 		stampit();
 		spin_lock_irq(&rtc->lock);
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_SEC);
 		spin_unlock_irq(&rtc->lock);
 		return 0;

 	case RTC_AIE_ON: {
 		unsigned long rtc_alarm;
 		u16 which_alarm;
 		int ret = 0;

 		stampit();

 		spin_lock_irq(&rtc->lock);

 		rtc_bfin_sync_pending();
 		if (rtc->rtc_alarm.tm_yday == -1) {
 			struct rtc_time now;
 			rtc_bfin_to_tm(bfin_read_RTC_STAT(), &now);
 			now.tm_sec = rtc->rtc_alarm.tm_sec;
 			now.tm_min = rtc->rtc_alarm.tm_min;
 			now.tm_hour = rtc->rtc_alarm.tm_hour;
 			ret = rtc_tm_to_time(&now, &rtc_alarm);
 			which_alarm = RTC_ISTAT_ALARM;
 		} else {
 			ret = rtc_tm_to_time(&rtc->rtc_alarm, &rtc_alarm);
 			which_alarm = RTC_ISTAT_ALARM_DAY;
 		}
 		if (ret == 0) {
 			bfin_write_RTC_ISTAT(which_alarm);
 			bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm));
 			bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | which_alarm);
 		}

 		spin_unlock_irq(&rtc->lock);

 		return ret;
 	}
 	case RTC_AIE_OFF:
 		stampit();
 		spin_lock_irq(&rtc->lock);
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY));
 		spin_unlock_irq(&rtc->lock);
 		return 0;
 	}

 	return -ENOIOCTLCMD;
 }

 static int bfin_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);

 	stampit();

 	spin_lock_irq(&rtc->lock);
 	rtc_bfin_sync_pending();
 	rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm);
 	spin_unlock_irq(&rtc->lock);

 	return 0;
 }

 static int bfin_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	int ret;
 	unsigned long now;

 	stampit();

 	spin_lock_irq(&rtc->lock);

 	ret = rtc_tm_to_time(tm, &now);
 	if (ret == 0) {
 		rtc_bfin_sync_pending();
 		bfin_write_RTC_STAT(rtc_time_to_bfin(now));
 	}

 	spin_unlock_irq(&rtc->lock);

 	return ret;
 }

 static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	stampit();
 	memcpy(&alrm->time, &rtc->rtc_alarm, sizeof(struct rtc_time));
 	alrm->pending = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY));
 	return 0;
 }

 static int bfin_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	stampit();
 	memcpy(&rtc->rtc_alarm, &alrm->time, sizeof(struct rtc_time));
 	return 0;
 }

 static int bfin_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 #define yesno(x) (x ? "yes" : "no")
 	u16 ictl = bfin_read_RTC_ICTL();
 	stampit();
 	seq_printf(seq, "alarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM));
 	seq_printf(seq, "wkalarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM_DAY));
 	seq_printf(seq, "seconds_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_SEC));
 	seq_printf(seq, "periodic_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_STOPWATCH));
 #ifdef DEBUG
 	seq_printf(seq, "RTC_STAT\t: 0x%08X\n", bfin_read_RTC_STAT());
 	seq_printf(seq, "RTC_ICTL\t: 0x%04X\n", bfin_read_RTC_ICTL());
 	seq_printf(seq, "RTC_ISTAT\t: 0x%04X\n", bfin_read_RTC_ISTAT());
 	seq_printf(seq, "RTC_SWCNT\t: 0x%04X\n", bfin_read_RTC_SWCNT());
 	seq_printf(seq, "RTC_ALARM\t: 0x%08X\n", bfin_read_RTC_ALARM());
 	seq_printf(seq, "RTC_PREN\t: 0x%04X\n", bfin_read_RTC_PREN());
 #endif
 	return 0;
 }

 static int bfin_irq_set_freq(struct device *dev, int freq)
 {
 	struct bfin_rtc *rtc = dev_get_drvdata(dev);
 	stampit();
 	rtc->rtc_dev->irq_freq = freq;
 	return 0;
 }

 static struct rtc_class_ops bfin_rtc_ops = {
 	.open          = bfin_rtc_open,
 	.release       = bfin_rtc_release,
 	.ioctl         = bfin_rtc_ioctl,
 	.read_time     = bfin_rtc_read_time,
 	.set_time      = bfin_rtc_set_time,
 	.read_alarm    = bfin_rtc_read_alarm,
 	.set_alarm     = bfin_rtc_set_alarm,
 	.proc          = bfin_rtc_proc,
 	.irq_set_freq  = bfin_irq_set_freq,
 };

 static int __devinit bfin_rtc_probe(struct platform_device *pdev)
 {
 	struct bfin_rtc *rtc;
 	int ret = 0;

 	stampit();

 	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
 	if (unlikely(!rtc))
 		return -ENOMEM;

 	spin_lock_init(&rtc->lock);

 	rtc->rtc_dev = rtc_device_register(pdev->name, &pdev->dev, &bfin_rtc_ops, THIS_MODULE);
 	if (unlikely(IS_ERR(rtc))) {
 		ret = PTR_ERR(rtc->rtc_dev);
 		goto err;
 	}
 	rtc->rtc_dev->irq_freq = 0;
 	rtc->rtc_dev->max_user_freq = (2 << 16); /* stopwatch is an unsigned 16 bit reg */

 	platform_set_drvdata(pdev, rtc);

 	return 0;

 err:
 	kfree(rtc);
 	return ret;
 }

 static int __devexit bfin_rtc_remove(struct platform_device *pdev)
 {
 	struct bfin_rtc *rtc = platform_get_drvdata(pdev);

 	rtc_device_unregister(rtc->rtc_dev);
 	platform_set_drvdata(pdev, NULL);
 	kfree(rtc);

 	return 0;
 }

 static struct platform_driver bfin_rtc_driver = {
 	.driver		= {
 		.name	= "rtc-bfin",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= bfin_rtc_probe,
 	.remove		= __devexit_p(bfin_rtc_remove),
 };

 static int __init bfin_rtc_init(void)
 {
 	stampit();
 	return platform_driver_register(&bfin_rtc_driver);
 }

 static void __exit bfin_rtc_exit(void)
 {
 	platform_driver_unregister(&bfin_rtc_driver);
 }

 module_init(bfin_rtc_init);
 module_exit(bfin_rtc_exit);

 MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver");
 MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
 MODULE_LICENSE("GPL");
	/*
	* Blackfin On-Chip Real Time Clock Driver
	* Supports BF53[123]/BF53[467]/BF54[2489]
	*
	* Copyright 2004-2007 Analog Devices Inc.
	*
	* Enter bugs at http://blackfin.uclinux.org/
	*
	* Licensed under the GPL-2 or later.
	*/

	/* The biggest issue we deal with in this driver is that register writes are
	* synced to the RTC frequency of 1Hz. So if you write to a register and
	* attempt to write again before the first write has completed, the new write
	* is simply discarded. This can easily be troublesome if userspace disables
	* one event (say periodic) and then right after enables an event (say alarm).
	* Since all events are maintained in the same interrupt mask register, if
	* we wrote to it to disable the first event and then wrote to it again to
	* enable the second event, that second event would not be enabled as the
	* write would be discarded and things quickly fall apart.
	*
	* To keep this delay from significantly degrading performance (we, in theory,
	* would have to sleep for up to 1 second everytime we wanted to write a
	* register), we only check the write pending status before we start to issue
	* a new write. We bank on the idea that it doesnt matter when the sync
	* happens so long as we don't attempt another write before it does. The only
	* time userspace would take this penalty is when they try and do multiple
	* operations right after another ... but in this case, they need to take the
	* sync penalty, so we should be OK.
	*
	* Also note that the RTC_ISTAT register does not suffer this penalty; its
	* writes to clear status registers complete immediately.
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/bcd.h>
	#include <linux/rtc.h>
	#include <linux/init.h>
	#include <linux/platform_device.h>
	#include <linux/seq_file.h>
	#include <linux/interrupt.h>
	#include <linux/spinlock.h>
	#include <linux/delay.h>

	#include <asm/blackfin.h>

	#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __FUNCTION__, __LINE__, ## args)
	#define stampit() stamp("here i am")

	struct bfin_rtc {
	struct rtc_device *rtc_dev;
	struct rtc_time rtc_alarm;
	spinlock_t lock;
	};

	/* Bit values for the ISTAT / ICTL registers */
	#define RTC_ISTAT_WRITE_COMPLETE 0x8000
	#define RTC_ISTAT_WRITE_PENDING 0x4000
	#define RTC_ISTAT_ALARM_DAY 0x0040
	#define RTC_ISTAT_24HR 0x0020
	#define RTC_ISTAT_HOUR 0x0010
	#define RTC_ISTAT_MIN 0x0008
	#define RTC_ISTAT_SEC 0x0004
	#define RTC_ISTAT_ALARM 0x0002
	#define RTC_ISTAT_STOPWATCH 0x0001

	/* Shift values for RTC_STAT register */
	#define DAY_BITS_OFF 17
	#define HOUR_BITS_OFF 12
	#define MIN_BITS_OFF 6
	#define SEC_BITS_OFF 0

	/* Some helper functions to convert between the common RTC notion of time
	* and the internal Blackfin notion that is stored in 32bits.
	*/
	static inline u32 rtc_time_to_bfin(unsigned long now)
	{
	u32 sec = (now % 60);
	u32 min = (now % (60 * 60)) / 60;
	u32 hour = (now % (60 * 60 * 24)) / (60 * 60);
	u32 days = (now / (60 * 60 * 24));
	return (sec << SEC_BITS_OFF) +
	(min << MIN_BITS_OFF) +
	(hour << HOUR_BITS_OFF) +
	(days << DAY_BITS_OFF);
	}
	static inline unsigned long rtc_bfin_to_time(u32 rtc_bfin)
	{
	return (((rtc_bfin >> SEC_BITS_OFF) & 0x003F)) +
	(((rtc_bfin >> MIN_BITS_OFF) & 0x003F) * 60) +
	(((rtc_bfin >> HOUR_BITS_OFF) & 0x001F) * 60 * 60) +
	(((rtc_bfin >> DAY_BITS_OFF) & 0x7FFF) * 60 * 60 * 24);
	}
	static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm)
	{
	rtc_time_to_tm(rtc_bfin_to_time(rtc_bfin), tm);
	}

	/* Wait for the previous write to a RTC register to complete.
	* Unfortunately, we can't sleep here as that introduces a race condition when
	* turning on interrupt events. Consider this:
	* - process sets alarm
	* - process enables alarm
	* - process sleeps while waiting for rtc write to sync
	* - interrupt fires while process is sleeping
	* - interrupt acks the event by writing to ISTAT
	* - interrupt sets the WRITE PENDING bit
	* - interrupt handler finishes
	* - process wakes up, sees WRITE PENDING bit set, goes to sleep
	* - interrupt fires while process is sleeping
	* If anyone can point out the obvious solution here, i'm listening :). This
	* shouldn't be an issue on an SMP or preempt system as this function should
	* only be called with the rtc lock held.
	*/
	static void rtc_bfin_sync_pending(void)
	{
	stampit();
	while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE)) {
	if (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING))
	break;
	}
	bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
	}

	static void rtc_bfin_reset(struct bfin_rtc *rtc)
	{
	/* Initialize the RTC. Enable pre-scaler to scale RTC clock
	* to 1Hz and clear interrupt/status registers. */
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_PREN(0x1);
	bfin_write_RTC_ICTL(0);
	bfin_write_RTC_SWCNT(0);
	bfin_write_RTC_ALARM(0);
	bfin_write_RTC_ISTAT(0xFFFF);
	spin_unlock_irq(&rtc->lock);
	}

	static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
	{
	struct platform_device *pdev = to_platform_device(dev_id);
	struct bfin_rtc *rtc = platform_get_drvdata(pdev);
	unsigned long events = 0;
	u16 rtc_istat;

	stampit();

	spin_lock_irq(&rtc->lock);

	rtc_istat = bfin_read_RTC_ISTAT();

	if (rtc_istat & (RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY)) {
	bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY);
	events \|= RTC_AF \| RTC_IRQF;
	}

	if (rtc_istat & RTC_ISTAT_STOPWATCH) {
	bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
	events \|= RTC_PF \| RTC_IRQF;
	bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
	}

	if (rtc_istat & RTC_ISTAT_SEC) {
	bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
	events \|= RTC_UF \| RTC_IRQF;
	}

	rtc_update_irq(rtc->rtc_dev, 1, events);

	spin_unlock_irq(&rtc->lock);

	return IRQ_HANDLED;
	}

	static int bfin_rtc_open(struct device *dev)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	int ret;

	stampit();

	ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, IRQF_DISABLED, "rtc-bfin", dev);
	if (unlikely(ret)) {
	dev_err(dev, "request RTC IRQ failed with %d\n", ret);
	return ret;
	}

	rtc_bfin_reset(rtc);

	return ret;
	}

	static void bfin_rtc_release(struct device *dev)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	stampit();
	rtc_bfin_reset(rtc);
	free_irq(IRQ_RTC, dev);
	}

	static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);

	stampit();

	switch (cmd) {
	case RTC_PIE_ON:
	stampit();
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_ISTAT(RTC_ISTAT_STOPWATCH);
	bfin_write_RTC_SWCNT(rtc->rtc_dev->irq_freq);
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() \| RTC_ISTAT_STOPWATCH);
	spin_unlock_irq(&rtc->lock);
	return 0;
	case RTC_PIE_OFF:
	stampit();
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_SWCNT(0);
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_STOPWATCH);
	spin_unlock_irq(&rtc->lock);
	return 0;

	case RTC_UIE_ON:
	stampit();
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() \| RTC_ISTAT_SEC);
	spin_unlock_irq(&rtc->lock);
	return 0;
	case RTC_UIE_OFF:
	stampit();
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~RTC_ISTAT_SEC);
	spin_unlock_irq(&rtc->lock);
	return 0;

	case RTC_AIE_ON: {
	unsigned long rtc_alarm;
	u16 which_alarm;
	int ret = 0;

	stampit();

	spin_lock_irq(&rtc->lock);

	rtc_bfin_sync_pending();
	if (rtc->rtc_alarm.tm_yday == -1) {
	struct rtc_time now;
	rtc_bfin_to_tm(bfin_read_RTC_STAT(), &now);
	now.tm_sec = rtc->rtc_alarm.tm_sec;
	now.tm_min = rtc->rtc_alarm.tm_min;
	now.tm_hour = rtc->rtc_alarm.tm_hour;
	ret = rtc_tm_to_time(&now, &rtc_alarm);
	which_alarm = RTC_ISTAT_ALARM;
	} else {
	ret = rtc_tm_to_time(&rtc->rtc_alarm, &rtc_alarm);
	which_alarm = RTC_ISTAT_ALARM_DAY;
	}
	if (ret == 0) {
	bfin_write_RTC_ISTAT(which_alarm);
	bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm));
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() \| which_alarm);
	}

	spin_unlock_irq(&rtc->lock);

	return ret;
	}
	case RTC_AIE_OFF:
	stampit();
	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & ~(RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY));
	spin_unlock_irq(&rtc->lock);
	return 0;
	}

	return -ENOIOCTLCMD;
	}

	static int bfin_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);

	stampit();

	spin_lock_irq(&rtc->lock);
	rtc_bfin_sync_pending();
	rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm);
	spin_unlock_irq(&rtc->lock);

	return 0;
	}

	static int bfin_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	int ret;
	unsigned long now;

	stampit();

	spin_lock_irq(&rtc->lock);

	ret = rtc_tm_to_time(tm, &now);
	if (ret == 0) {
	rtc_bfin_sync_pending();
	bfin_write_RTC_STAT(rtc_time_to_bfin(now));
	}

	spin_unlock_irq(&rtc->lock);

	return ret;
	}

	static int bfin_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	stampit();
	memcpy(&alrm->time, &rtc->rtc_alarm, sizeof(struct rtc_time));
	alrm->pending = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY));
	return 0;
	}

	static int bfin_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	stampit();
	memcpy(&rtc->rtc_alarm, &alrm->time, sizeof(struct rtc_time));
	return 0;
	}

	static int bfin_rtc_proc(struct device dev, struct seq_file seq)
	{
	#define yesno(x) (x ? "yes" : "no")
	u16 ictl = bfin_read_RTC_ICTL();
	stampit();
	seq_printf(seq, "alarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM));
	seq_printf(seq, "wkalarm_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_ALARM_DAY));
	seq_printf(seq, "seconds_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_SEC));
	seq_printf(seq, "periodic_IRQ\t: %s\n", yesno(ictl & RTC_ISTAT_STOPWATCH));
	#ifdef DEBUG
	seq_printf(seq, "RTC_STAT\t: 0x%08X\n", bfin_read_RTC_STAT());
	seq_printf(seq, "RTC_ICTL\t: 0x%04X\n", bfin_read_RTC_ICTL());
	seq_printf(seq, "RTC_ISTAT\t: 0x%04X\n", bfin_read_RTC_ISTAT());
	seq_printf(seq, "RTC_SWCNT\t: 0x%04X\n", bfin_read_RTC_SWCNT());
	seq_printf(seq, "RTC_ALARM\t: 0x%08X\n", bfin_read_RTC_ALARM());
	seq_printf(seq, "RTC_PREN\t: 0x%04X\n", bfin_read_RTC_PREN());
	#endif
	return 0;
	}

	static int bfin_irq_set_freq(struct device *dev, int freq)
	{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	stampit();
	rtc->rtc_dev->irq_freq = freq;
	return 0;
	}

	static struct rtc_class_ops bfin_rtc_ops = {
	.open = bfin_rtc_open,
	.release = bfin_rtc_release,
	.ioctl = bfin_rtc_ioctl,
	.read_time = bfin_rtc_read_time,
	.set_time = bfin_rtc_set_time,
	.read_alarm = bfin_rtc_read_alarm,
	.set_alarm = bfin_rtc_set_alarm,
	.proc = bfin_rtc_proc,
	.irq_set_freq = bfin_irq_set_freq,
	};

	static int __devinit bfin_rtc_probe(struct platform_device *pdev)
	{
	struct bfin_rtc *rtc;
	int ret = 0;

	stampit();

	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
	if (unlikely(!rtc))
	return -ENOMEM;

	spin_lock_init(&rtc->lock);

	rtc->rtc_dev = rtc_device_register(pdev->name, &pdev->dev, &bfin_rtc_ops, THIS_MODULE);
	if (unlikely(IS_ERR(rtc))) {
	ret = PTR_ERR(rtc->rtc_dev);
	goto err;
	}
	rtc->rtc_dev->irq_freq = 0;
	rtc->rtc_dev->max_user_freq = (2 << 16); /* stopwatch is an unsigned 16 bit reg */

	platform_set_drvdata(pdev, rtc);

	return 0;

	err:
	kfree(rtc);
	return ret;
	}

	static int __devexit bfin_rtc_remove(struct platform_device *pdev)
	{
	struct bfin_rtc *rtc = platform_get_drvdata(pdev);

	rtc_device_unregister(rtc->rtc_dev);
	platform_set_drvdata(pdev, NULL);
	kfree(rtc);

	return 0;
	}

	static struct platform_driver bfin_rtc_driver = {
	.driver = {
	.name = "rtc-bfin",
	.owner = THIS_MODULE,
	},
	.probe = bfin_rtc_probe,
	.remove = __devexit_p(bfin_rtc_remove),
	};

	static int __init bfin_rtc_init(void)
	{
	stampit();
	return platform_driver_register(&bfin_rtc_driver);
	}

	static void __exit bfin_rtc_exit(void)
	{
	platform_driver_unregister(&bfin_rtc_driver);
	}

	module_init(bfin_rtc_init);
	module_exit(bfin_rtc_exit);

	MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver");
	MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
	MODULE_LICENSE("GPL");