[net-next-2.6.git] / drivers / rtc / rtc-bfin.c

/*
 * Blackfin On-Chip Real Time Clock Driver
 *  Supports BF51x/BF52x/BF53[123]/BF53[467]/BF54x
 *
 * Copyright 2004-2009 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.
 */

/* It may seem odd that there is no SWCNT code in here (which would be exposed
 * via the periodic interrupt event, or PIE).  Since the Blackfin RTC peripheral
 * runs in units of seconds (N/HZ) but the Linux framework runs in units of HZ
 * (2^N HZ), there is no point in keeping code that only provides 1 HZ PIEs.
 * The same exact behavior can be accomplished by using the update interrupt
 * event (UIE).  Maybe down the line the RTC peripheral will suck less in which
 * case we can re-introduce PIE support.
 */

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

#include <asm/blackfin.h>

#define dev_dbg_stamp(dev) dev_dbg(dev, "%s:%i: here i am\n", __func__, __LINE__)

struct bfin_rtc {
	struct rtc_device *rtc_dev;
	struct rtc_time rtc_alarm;
	u16 rtc_wrote_regs;
};

/* 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 encoded 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);
}

/**
 *	bfin_rtc_sync_pending - make sure pending writes have complete
 *
 * 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.
 *
 * Other options:
 *  - disable PREN so the sync happens at 32.768kHZ ... but this changes the
 *    inc rate for all RTC registers from 1HZ to 32.768kHZ ...
 *  - use the write complete IRQ
 */
/*
static void bfin_rtc_sync_pending_polled(void)
{
	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 DECLARE_COMPLETION(bfin_write_complete);
static void bfin_rtc_sync_pending(struct device *dev)
{
	dev_dbg_stamp(dev);
	while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)
		wait_for_completion_timeout(&bfin_write_complete, HZ * 5);
	dev_dbg_stamp(dev);
}

/**
 *	bfin_rtc_reset - set RTC to sane/known state
 *
 * Initialize the RTC.  Enable pre-scaler to scale RTC clock
 * to 1Hz and clear interrupt/status registers.
 */
static void bfin_rtc_reset(struct device *dev, u16 rtc_ictl)
{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	dev_dbg_stamp(dev);
	bfin_rtc_sync_pending(dev);
	bfin_write_RTC_PREN(0x1);
	bfin_write_RTC_ICTL(rtc_ictl);
	bfin_write_RTC_ALARM(0);
	bfin_write_RTC_ISTAT(0xFFFF);
	rtc->rtc_wrote_regs = 0;
}

/**
 *	bfin_rtc_interrupt - handle interrupt from RTC
 *
 * Since we handle all RTC events here, we have to make sure the requested
 * interrupt is enabled (in RTC_ICTL) as the event status register (RTC_ISTAT)
 * always gets updated regardless of the interrupt being enabled.  So when one
 * even we care about (e.g. stopwatch) goes off, we don't want to turn around
 * and say that other events have happened as well (e.g. second).  We do not
 * have to worry about pending writes to the RTC_ICTL register as interrupts
 * only fire if they are enabled in the RTC_ICTL register.
 */
static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
{
	struct device *dev = dev_id;
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	unsigned long events = 0;
	bool write_complete = false;
	u16 rtc_istat, rtc_ictl;

	dev_dbg_stamp(dev);

	rtc_istat = bfin_read_RTC_ISTAT();
	rtc_ictl = bfin_read_RTC_ICTL();

	if (rtc_istat & RTC_ISTAT_WRITE_COMPLETE) {
		bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
		write_complete = true;
		complete(&bfin_write_complete);
	}

	if (rtc_ictl & (RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY)) {
		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_ictl & RTC_ISTAT_SEC) {
		if (rtc_istat & RTC_ISTAT_SEC) {
			bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
			events |= RTC_UF | RTC_IRQF;
		}
	}

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

	if (write_complete || events)
		return IRQ_HANDLED;
	else
		return IRQ_NONE;
}

static void bfin_rtc_int_set(u16 rtc_int)
{
	bfin_write_RTC_ISTAT(rtc_int);
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() | rtc_int);
}
static void bfin_rtc_int_clear(u16 rtc_int)
{
	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & rtc_int);
}
static void bfin_rtc_int_set_alarm(struct bfin_rtc *rtc)
{
	/* Blackfin has different bits for whether the alarm is
	 * more than 24 hours away.
	 */
	bfin_rtc_int_set(rtc->rtc_alarm.tm_yday == -1 ? RTC_ISTAT_ALARM : RTC_ISTAT_ALARM_DAY);
}
static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	int ret = 0;

	dev_dbg_stamp(dev);

	bfin_rtc_sync_pending(dev);

	switch (cmd) {
	case RTC_UIE_ON:
		dev_dbg_stamp(dev);
		bfin_rtc_int_set(RTC_ISTAT_SEC);
		break;
	case RTC_UIE_OFF:
		dev_dbg_stamp(dev);
		bfin_rtc_int_clear(~RTC_ISTAT_SEC);
		break;

	case RTC_AIE_ON:
		dev_dbg_stamp(dev);
		bfin_rtc_int_set_alarm(rtc);
		break;
	case RTC_AIE_OFF:
		dev_dbg_stamp(dev);
		bfin_rtc_int_clear(~(RTC_ISTAT_ALARM | RTC_ISTAT_ALARM_DAY));
		break;

	default:
		dev_dbg_stamp(dev);
		ret = -ENOIOCTLCMD;
	}

	return ret;
}

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

	dev_dbg_stamp(dev);

	if (rtc->rtc_wrote_regs & 0x1)
		bfin_rtc_sync_pending(dev);

	rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm);

	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;

	dev_dbg_stamp(dev);

	ret = rtc_tm_to_time(tm, &now);
	if (ret == 0) {
		if (rtc->rtc_wrote_regs & 0x1)
			bfin_rtc_sync_pending(dev);
		bfin_write_RTC_STAT(rtc_time_to_bfin(now));
		rtc->rtc_wrote_regs = 0x1;
	}

	return ret;
}

static int bfin_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	dev_dbg_stamp(dev);
	alrm->time = rtc->rtc_alarm;
	bfin_rtc_sync_pending(dev);
	alrm->enabled = !!(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);
	unsigned long rtc_alarm;

	dev_dbg_stamp(dev);

	if (rtc_tm_to_time(&alrm->time, &rtc_alarm))
		return -EINVAL;

	rtc->rtc_alarm = alrm->time;

	bfin_rtc_sync_pending(dev);
	bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm));
	if (alrm->enabled)
		bfin_rtc_int_set_alarm(rtc);

	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();
	dev_dbg_stamp(dev);
	seq_printf(seq,
		"alarm_IRQ\t: %s\n"
		"wkalarm_IRQ\t: %s\n"
		"seconds_IRQ\t: %s\n",
		yesno(ictl & RTC_ISTAT_ALARM),
		yesno(ictl & RTC_ISTAT_ALARM_DAY),
		yesno(ictl & RTC_ISTAT_SEC));
	return 0;
#undef yesno
}

static struct rtc_class_ops bfin_rtc_ops = {
	.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,
};

static int __devinit bfin_rtc_probe(struct platform_device *pdev)
{
	struct bfin_rtc *rtc;
	struct device *dev = &pdev->dev;
	int ret = 0;
	unsigned long timeout = jiffies + HZ;

	dev_dbg_stamp(dev);

	/* Allocate memory for our RTC struct */
	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
	if (unlikely(!rtc))
		return -ENOMEM;
	platform_set_drvdata(pdev, rtc);
	device_init_wakeup(dev, 1);

	/* Register our RTC with the RTC framework */
	rtc->rtc_dev = rtc_device_register(pdev->name, dev, &bfin_rtc_ops,
						THIS_MODULE);
	if (unlikely(IS_ERR(rtc->rtc_dev))) {
		ret = PTR_ERR(rtc->rtc_dev);
		goto err;
	}

	/* Grab the IRQ and init the hardware */
	ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, 0, pdev->name, dev);
	if (unlikely(ret))
		goto err_reg;
	/* sometimes the bootloader touched things, but the write complete was not
	 * enabled, so let's just do a quick timeout here since the IRQ will not fire ...
	 */
	while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)
		if (time_after(jiffies, timeout))
			break;
	bfin_rtc_reset(dev, RTC_ISTAT_WRITE_COMPLETE);
	bfin_write_RTC_SWCNT(0);

	return 0;

err_reg:
	rtc_device_unregister(rtc->rtc_dev);
err:
	kfree(rtc);
	return ret;
}

static int __devexit bfin_rtc_remove(struct platform_device *pdev)
{
	struct bfin_rtc *rtc = platform_get_drvdata(pdev);
	struct device *dev = &pdev->dev;

	bfin_rtc_reset(dev, 0);
	free_irq(IRQ_RTC, dev);
	rtc_device_unregister(rtc->rtc_dev);
	platform_set_drvdata(pdev, NULL);
	kfree(rtc);

	return 0;
}

#ifdef CONFIG_PM
static int bfin_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
	if (device_may_wakeup(&pdev->dev)) {
		enable_irq_wake(IRQ_RTC);
		bfin_rtc_sync_pending(&pdev->dev);
	} else
		bfin_rtc_int_clear(0);

	return 0;
}

static int bfin_rtc_resume(struct platform_device *pdev)
{
	if (device_may_wakeup(&pdev->dev))
		disable_irq_wake(IRQ_RTC);
	else
		bfin_write_RTC_ISTAT(-1);

	return 0;
}
#else
# define bfin_rtc_suspend NULL
# define bfin_rtc_resume  NULL
#endif

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

static int __init bfin_rtc_init(void)
{
	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");
MODULE_ALIAS("platform:rtc-bfin");
Commit	Line	Data
	1	/*
	2	* Blackfin On-Chip Real Time Clock Driver
	3	* Supports BF51x/BF52x/BF53[123]/BF53[467]/BF54x
	4	*
	5	* Copyright 2004-2009 Analog Devices Inc.
	6	*
	7	* Enter bugs at http://blackfin.uclinux.org/
	8	*
	9	* Licensed under the GPL-2 or later.
	10	*/
	11
	12	/* The biggest issue we deal with in this driver is that register writes are
	13	* synced to the RTC frequency of 1Hz. So if you write to a register and
	14	* attempt to write again before the first write has completed, the new write
	15	* is simply discarded. This can easily be troublesome if userspace disables
	16	* one event (say periodic) and then right after enables an event (say alarm).
	17	* Since all events are maintained in the same interrupt mask register, if
	18	* we wrote to it to disable the first event and then wrote to it again to
	19	* enable the second event, that second event would not be enabled as the
	20	* write would be discarded and things quickly fall apart.
	21	*
	22	* To keep this delay from significantly degrading performance (we, in theory,
	23	* would have to sleep for up to 1 second everytime we wanted to write a
	24	* register), we only check the write pending status before we start to issue
	25	* a new write. We bank on the idea that it doesnt matter when the sync
	26	* happens so long as we don't attempt another write before it does. The only
	27	* time userspace would take this penalty is when they try and do multiple
	28	* operations right after another ... but in this case, they need to take the
	29	* sync penalty, so we should be OK.
	30	*
	31	* Also note that the RTC_ISTAT register does not suffer this penalty; its
	32	* writes to clear status registers complete immediately.
	33	*/
	34
	35	/* It may seem odd that there is no SWCNT code in here (which would be exposed
	36	* via the periodic interrupt event, or PIE). Since the Blackfin RTC peripheral
	37	* runs in units of seconds (N/HZ) but the Linux framework runs in units of HZ
	38	* (2^N HZ), there is no point in keeping code that only provides 1 HZ PIEs.
	39	* The same exact behavior can be accomplished by using the update interrupt
	40	* event (UIE). Maybe down the line the RTC peripheral will suck less in which
	41	* case we can re-introduce PIE support.
	42	*/
	43
	44	#include <linux/bcd.h>
	45	#include <linux/completion.h>
	46	#include <linux/delay.h>
	47	#include <linux/init.h>
	48	#include <linux/interrupt.h>
	49	#include <linux/kernel.h>
	50	#include <linux/module.h>
	51	#include <linux/platform_device.h>
	52	#include <linux/rtc.h>
	53	#include <linux/seq_file.h>
	54	#include <linux/slab.h>
	55
	56	#include <asm/blackfin.h>
	57
	58	#define dev_dbg_stamp(dev) dev_dbg(dev, "%s:%i: here i am\n", __func__, __LINE__)
	59
	60	struct bfin_rtc {
	61	struct rtc_device *rtc_dev;
	62	struct rtc_time rtc_alarm;
	63	u16 rtc_wrote_regs;
	64	};
	65
	66	/* Bit values for the ISTAT / ICTL registers */
	67	#define RTC_ISTAT_WRITE_COMPLETE 0x8000
	68	#define RTC_ISTAT_WRITE_PENDING 0x4000
	69	#define RTC_ISTAT_ALARM_DAY 0x0040
	70	#define RTC_ISTAT_24HR 0x0020
	71	#define RTC_ISTAT_HOUR 0x0010
	72	#define RTC_ISTAT_MIN 0x0008
	73	#define RTC_ISTAT_SEC 0x0004
	74	#define RTC_ISTAT_ALARM 0x0002
	75	#define RTC_ISTAT_STOPWATCH 0x0001
	76
	77	/* Shift values for RTC_STAT register */
	78	#define DAY_BITS_OFF 17
	79	#define HOUR_BITS_OFF 12
	80	#define MIN_BITS_OFF 6
	81	#define SEC_BITS_OFF 0
	82
	83	/* Some helper functions to convert between the common RTC notion of time
	84	* and the internal Blackfin notion that is encoded in 32bits.
	85	*/
	86	static inline u32 rtc_time_to_bfin(unsigned long now)
	87	{
	88	u32 sec = (now % 60);
	89	u32 min = (now % (60 * 60)) / 60;
	90	u32 hour = (now % (60 * 60 * 24)) / (60 * 60);
	91	u32 days = (now / (60 * 60 * 24));
	92	return (sec << SEC_BITS_OFF) +
	93	(min << MIN_BITS_OFF) +
	94	(hour << HOUR_BITS_OFF) +
	95	(days << DAY_BITS_OFF);
	96	}
	97	static inline unsigned long rtc_bfin_to_time(u32 rtc_bfin)
	98	{
	99	return (((rtc_bfin >> SEC_BITS_OFF) & 0x003F)) +
	100	(((rtc_bfin >> MIN_BITS_OFF) & 0x003F) * 60) +
	101	(((rtc_bfin >> HOUR_BITS_OFF) & 0x001F) * 60 * 60) +
	102	(((rtc_bfin >> DAY_BITS_OFF) & 0x7FFF) * 60 * 60 * 24);
	103	}
	104	static inline void rtc_bfin_to_tm(u32 rtc_bfin, struct rtc_time *tm)
	105	{
	106	rtc_time_to_tm(rtc_bfin_to_time(rtc_bfin), tm);
	107	}
	108
	109	/**
	110	* bfin_rtc_sync_pending - make sure pending writes have complete
	111	*
	112	* Wait for the previous write to a RTC register to complete.
	113	* Unfortunately, we can't sleep here as that introduces a race condition when
	114	* turning on interrupt events. Consider this:
	115	* - process sets alarm
	116	* - process enables alarm
	117	* - process sleeps while waiting for rtc write to sync
	118	* - interrupt fires while process is sleeping
	119	* - interrupt acks the event by writing to ISTAT
	120	* - interrupt sets the WRITE PENDING bit
	121	* - interrupt handler finishes
	122	* - process wakes up, sees WRITE PENDING bit set, goes to sleep
	123	* - interrupt fires while process is sleeping
	124	* If anyone can point out the obvious solution here, i'm listening :). This
	125	* shouldn't be an issue on an SMP or preempt system as this function should
	126	* only be called with the rtc lock held.
	127	*
	128	* Other options:
	129	* - disable PREN so the sync happens at 32.768kHZ ... but this changes the
	130	* inc rate for all RTC registers from 1HZ to 32.768kHZ ...
	131	* - use the write complete IRQ
	132	*/
	133	/*
	134	static void bfin_rtc_sync_pending_polled(void)
	135	{
	136	while (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_COMPLETE))
	137	if (!(bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING))
	138	break;
	139	bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
	140	}
	141	*/
	142	static DECLARE_COMPLETION(bfin_write_complete);
	143	static void bfin_rtc_sync_pending(struct device *dev)
	144	{
	145	dev_dbg_stamp(dev);
	146	while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)
	147	wait_for_completion_timeout(&bfin_write_complete, HZ * 5);
	148	dev_dbg_stamp(dev);
	149	}
	150
	151	/**
	152	* bfin_rtc_reset - set RTC to sane/known state
	153	*
	154	* Initialize the RTC. Enable pre-scaler to scale RTC clock
	155	* to 1Hz and clear interrupt/status registers.
	156	*/
	157	static void bfin_rtc_reset(struct device *dev, u16 rtc_ictl)
	158	{
	159	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	160	dev_dbg_stamp(dev);
	161	bfin_rtc_sync_pending(dev);
	162	bfin_write_RTC_PREN(0x1);
	163	bfin_write_RTC_ICTL(rtc_ictl);
	164	bfin_write_RTC_ALARM(0);
	165	bfin_write_RTC_ISTAT(0xFFFF);
	166	rtc->rtc_wrote_regs = 0;
	167	}
	168
	169	/**
	170	* bfin_rtc_interrupt - handle interrupt from RTC
	171	*
	172	* Since we handle all RTC events here, we have to make sure the requested
	173	* interrupt is enabled (in RTC_ICTL) as the event status register (RTC_ISTAT)
	174	* always gets updated regardless of the interrupt being enabled. So when one
	175	* even we care about (e.g. stopwatch) goes off, we don't want to turn around
	176	* and say that other events have happened as well (e.g. second). We do not
	177	* have to worry about pending writes to the RTC_ICTL register as interrupts
	178	* only fire if they are enabled in the RTC_ICTL register.
	179	*/
	180	static irqreturn_t bfin_rtc_interrupt(int irq, void *dev_id)
	181	{
	182	struct device *dev = dev_id;
	183	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	184	unsigned long events = 0;
	185	bool write_complete = false;
	186	u16 rtc_istat, rtc_ictl;
	187
	188	dev_dbg_stamp(dev);
	189
	190	rtc_istat = bfin_read_RTC_ISTAT();
	191	rtc_ictl = bfin_read_RTC_ICTL();
	192
	193	if (rtc_istat & RTC_ISTAT_WRITE_COMPLETE) {
	194	bfin_write_RTC_ISTAT(RTC_ISTAT_WRITE_COMPLETE);
	195	write_complete = true;
	196	complete(&bfin_write_complete);
	197	}
	198
	199	if (rtc_ictl & (RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY)) {
	200	if (rtc_istat & (RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY)) {
	201	bfin_write_RTC_ISTAT(RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY);
	202	events \|= RTC_AF \| RTC_IRQF;
	203	}
	204	}
	205
	206	if (rtc_ictl & RTC_ISTAT_SEC) {
	207	if (rtc_istat & RTC_ISTAT_SEC) {
	208	bfin_write_RTC_ISTAT(RTC_ISTAT_SEC);
	209	events \|= RTC_UF \| RTC_IRQF;
	210	}
	211	}
	212
	213	if (events)
	214	rtc_update_irq(rtc->rtc_dev, 1, events);
	215
	216	if (write_complete \|\| events)
	217	return IRQ_HANDLED;
	218	else
	219	return IRQ_NONE;
	220	}
	221
	222	static void bfin_rtc_int_set(u16 rtc_int)
	223	{
	224	bfin_write_RTC_ISTAT(rtc_int);
	225	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() \| rtc_int);
	226	}
	227	static void bfin_rtc_int_clear(u16 rtc_int)
	228	{
	229	bfin_write_RTC_ICTL(bfin_read_RTC_ICTL() & rtc_int);
	230	}
	231	static void bfin_rtc_int_set_alarm(struct bfin_rtc *rtc)
	232	{
	233	/* Blackfin has different bits for whether the alarm is
	234	* more than 24 hours away.
	235	*/
	236	bfin_rtc_int_set(rtc->rtc_alarm.tm_yday == -1 ? RTC_ISTAT_ALARM : RTC_ISTAT_ALARM_DAY);
	237	}
	238	static int bfin_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
	239	{
	240	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	241	int ret = 0;
	242
	243	dev_dbg_stamp(dev);
	244
	245	bfin_rtc_sync_pending(dev);
	246
	247	switch (cmd) {
	248	case RTC_UIE_ON:
	249	dev_dbg_stamp(dev);
	250	bfin_rtc_int_set(RTC_ISTAT_SEC);
	251	break;
	252	case RTC_UIE_OFF:
	253	dev_dbg_stamp(dev);
	254	bfin_rtc_int_clear(~RTC_ISTAT_SEC);
	255	break;
	256
	257	case RTC_AIE_ON:
	258	dev_dbg_stamp(dev);
	259	bfin_rtc_int_set_alarm(rtc);
	260	break;
	261	case RTC_AIE_OFF:
	262	dev_dbg_stamp(dev);
	263	bfin_rtc_int_clear(~(RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY));
	264	break;
	265
	266	default:
	267	dev_dbg_stamp(dev);
	268	ret = -ENOIOCTLCMD;
	269	}
	270
	271	return ret;
	272	}
	273
	274	static int bfin_rtc_read_time(struct device dev, struct rtc_time tm)
	275	{
	276	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	277
	278	dev_dbg_stamp(dev);
	279
	280	if (rtc->rtc_wrote_regs & 0x1)
	281	bfin_rtc_sync_pending(dev);
	282
	283	rtc_bfin_to_tm(bfin_read_RTC_STAT(), tm);
	284
	285	return 0;
	286	}
	287
	288	static int bfin_rtc_set_time(struct device dev, struct rtc_time tm)
	289	{
	290	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	291	int ret;
	292	unsigned long now;
	293
	294	dev_dbg_stamp(dev);
	295
	296	ret = rtc_tm_to_time(tm, &now);
	297	if (ret == 0) {
	298	if (rtc->rtc_wrote_regs & 0x1)
	299	bfin_rtc_sync_pending(dev);
	300	bfin_write_RTC_STAT(rtc_time_to_bfin(now));
	301	rtc->rtc_wrote_regs = 0x1;
	302	}
	303
	304	return ret;
	305	}
	306
	307	static int bfin_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	308	{
	309	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	310	dev_dbg_stamp(dev);
	311	alrm->time = rtc->rtc_alarm;
	312	bfin_rtc_sync_pending(dev);
	313	alrm->enabled = !!(bfin_read_RTC_ICTL() & (RTC_ISTAT_ALARM \| RTC_ISTAT_ALARM_DAY));
	314	return 0;
	315	}
	316
	317	static int bfin_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	318	{
	319	struct bfin_rtc *rtc = dev_get_drvdata(dev);
	320	unsigned long rtc_alarm;
	321
	322	dev_dbg_stamp(dev);
	323
	324	if (rtc_tm_to_time(&alrm->time, &rtc_alarm))
	325	return -EINVAL;
	326
	327	rtc->rtc_alarm = alrm->time;
	328
	329	bfin_rtc_sync_pending(dev);
	330	bfin_write_RTC_ALARM(rtc_time_to_bfin(rtc_alarm));
	331	if (alrm->enabled)
	332	bfin_rtc_int_set_alarm(rtc);
	333
	334	return 0;
	335	}
	336
	337	static int bfin_rtc_proc(struct device dev, struct seq_file seq)
	338	{
	339	#define yesno(x) ((x) ? "yes" : "no")
	340	u16 ictl = bfin_read_RTC_ICTL();
	341	dev_dbg_stamp(dev);
	342	seq_printf(seq,
	343	"alarm_IRQ\t: %s\n"
	344	"wkalarm_IRQ\t: %s\n"
	345	"seconds_IRQ\t: %s\n",
	346	yesno(ictl & RTC_ISTAT_ALARM),
	347	yesno(ictl & RTC_ISTAT_ALARM_DAY),
	348	yesno(ictl & RTC_ISTAT_SEC));
	349	return 0;
	350	#undef yesno
	351	}
	352
	353	static struct rtc_class_ops bfin_rtc_ops = {
	354	.ioctl = bfin_rtc_ioctl,
	355	.read_time = bfin_rtc_read_time,
	356	.set_time = bfin_rtc_set_time,
	357	.read_alarm = bfin_rtc_read_alarm,
	358	.set_alarm = bfin_rtc_set_alarm,
	359	.proc = bfin_rtc_proc,
	360	};
	361
	362	static int __devinit bfin_rtc_probe(struct platform_device *pdev)
	363	{
	364	struct bfin_rtc *rtc;
	365	struct device *dev = &pdev->dev;
	366	int ret = 0;
	367	unsigned long timeout = jiffies + HZ;
	368
	369	dev_dbg_stamp(dev);
	370
	371	/* Allocate memory for our RTC struct */
	372	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
	373	if (unlikely(!rtc))
	374	return -ENOMEM;
	375	platform_set_drvdata(pdev, rtc);
	376	device_init_wakeup(dev, 1);
	377
	378	/* Register our RTC with the RTC framework */
	379	rtc->rtc_dev = rtc_device_register(pdev->name, dev, &bfin_rtc_ops,
	380	THIS_MODULE);
	381	if (unlikely(IS_ERR(rtc->rtc_dev))) {
	382	ret = PTR_ERR(rtc->rtc_dev);
	383	goto err;
	384	}
	385
	386	/* Grab the IRQ and init the hardware */
	387	ret = request_irq(IRQ_RTC, bfin_rtc_interrupt, 0, pdev->name, dev);
	388	if (unlikely(ret))
	389	goto err_reg;
	390	/* sometimes the bootloader touched things, but the write complete was not
	391	* enabled, so let's just do a quick timeout here since the IRQ will not fire ...
	392	*/
	393	while (bfin_read_RTC_ISTAT() & RTC_ISTAT_WRITE_PENDING)
	394	if (time_after(jiffies, timeout))
	395	break;
	396	bfin_rtc_reset(dev, RTC_ISTAT_WRITE_COMPLETE);
	397	bfin_write_RTC_SWCNT(0);
	398
	399	return 0;
	400
	401	err_reg:
	402	rtc_device_unregister(rtc->rtc_dev);
	403	err:
	404	kfree(rtc);
	405	return ret;
	406	}
	407
	408	static int __devexit bfin_rtc_remove(struct platform_device *pdev)
	409	{
	410	struct bfin_rtc *rtc = platform_get_drvdata(pdev);
	411	struct device *dev = &pdev->dev;
	412
	413	bfin_rtc_reset(dev, 0);
	414	free_irq(IRQ_RTC, dev);
	415	rtc_device_unregister(rtc->rtc_dev);
	416	platform_set_drvdata(pdev, NULL);
	417	kfree(rtc);
	418
	419	return 0;
	420	}
	421
	422	#ifdef CONFIG_PM
	423	static int bfin_rtc_suspend(struct platform_device *pdev, pm_message_t state)
	424	{
	425	if (device_may_wakeup(&pdev->dev)) {
	426	enable_irq_wake(IRQ_RTC);
	427	bfin_rtc_sync_pending(&pdev->dev);
	428	} else
	429	bfin_rtc_int_clear(0);
	430
	431	return 0;
	432	}
	433
	434	static int bfin_rtc_resume(struct platform_device *pdev)
	435	{
	436	if (device_may_wakeup(&pdev->dev))
	437	disable_irq_wake(IRQ_RTC);
	438	else
	439	bfin_write_RTC_ISTAT(-1);
	440
	441	return 0;
	442	}
	443	#else
	444	# define bfin_rtc_suspend NULL
	445	# define bfin_rtc_resume NULL
	446	#endif
	447
	448	static struct platform_driver bfin_rtc_driver = {
	449	.driver = {
	450	.name = "rtc-bfin",
	451	.owner = THIS_MODULE,
	452	},
	453	.probe = bfin_rtc_probe,
	454	.remove = __devexit_p(bfin_rtc_remove),
	455	.suspend = bfin_rtc_suspend,
	456	.resume = bfin_rtc_resume,
	457	};
	458
	459	static int __init bfin_rtc_init(void)
	460	{
	461	return platform_driver_register(&bfin_rtc_driver);
	462	}
	463
	464	static void __exit bfin_rtc_exit(void)
	465	{
	466	platform_driver_unregister(&bfin_rtc_driver);
	467	}
	468
	469	module_init(bfin_rtc_init);
	470	module_exit(bfin_rtc_exit);
	471
	472	MODULE_DESCRIPTION("Blackfin On-Chip Real Time Clock Driver");
	473	MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
	474	MODULE_LICENSE("GPL");
	475	MODULE_ALIAS("platform:rtc-bfin");