drivers/rtc/rtc-at91sam9.c - kernel/msm-4.9 - Gitiles

 /*
  * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
  *
  * (C) 2007 Michel Benoit
  *
  * Based on rtc-at91rm9200.c by Rick Bronson
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/time.h>
 #include <linux/rtc.h>
 #include <linux/interrupt.h>
 #include <linux/ioctl.h>
 #include <linux/slab.h>

 #include <mach/board.h>
 #include <mach/at91_rtt.h>
 #include <mach/cpu.h>


 /*
  * This driver uses two configurable hardware resources that live in the
  * AT91SAM9 backup power domain (intended to be powered at all times)
  * to implement the Real Time Clock interfaces
  *
  *  - A "Real-time Timer" (RTT) counts up in seconds from a base time.
  *    We can't assign the counter value (CRTV) ... but we can reset it.
  *
  *  - One of the "General Purpose Backup Registers" (GPBRs) holds the
  *    base time, normally an offset from the beginning of the POSIX
  *    epoch (1970-Jan-1 00:00:00 UTC).  Some systems also include the
  *    local timezone's offset.
  *
  * The RTC's value is the RTT counter plus that offset.  The RTC's alarm
  * is likewise a base (ALMV) plus that offset.
  *
  * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
  * choose from, or a "real" RTC module.  All systems have multiple GPBR
  * registers available, likewise usable for more than "RTC" support.
  */

 /*
  * We store ALARM_DISABLED in ALMV to record that no alarm is set.
  * It's also the reset value for that field.
  */
 #define ALARM_DISABLED	((u32)~0)


 struct sam9_rtc {
 	void __iomem		*rtt;
 	struct rtc_device	*rtcdev;
 	u32			imr;
 };

 #define rtt_readl(rtc, field) \
 	__raw_readl((rtc)->rtt + AT91_RTT_ ## field)
 #define rtt_writel(rtc, field, val) \
 	__raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)

 #define gpbr_readl(rtc) \
 	at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
 #define gpbr_writel(rtc, val) \
 	at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))

 /*
  * Read current time and date in RTC
  */
 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	u32 secs, secs2;
 	u32 offset;

 	/* read current time offset */
 	offset = gpbr_readl(rtc);
 	if (offset == 0)
 		return -EILSEQ;

 	/* reread the counter to help sync the two clock domains */
 	secs = rtt_readl(rtc, VR);
 	secs2 = rtt_readl(rtc, VR);
 	if (secs != secs2)
 		secs = rtt_readl(rtc, VR);

 	rtc_time_to_tm(offset + secs, tm);

 	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
 		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 		tm->tm_hour, tm->tm_min, tm->tm_sec);

 	return 0;
 }

 /*
  * Set current time and date in RTC
  */
 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	int err;
 	u32 offset, alarm, mr;
 	unsigned long secs;

 	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
 		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 		tm->tm_hour, tm->tm_min, tm->tm_sec);

 	err = rtc_tm_to_time(tm, &secs);
 	if (err != 0)
 		return err;

 	mr = rtt_readl(rtc, MR);

 	/* disable interrupts */
 	rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));

 	/* read current time offset */
 	offset = gpbr_readl(rtc);

 	/* store the new base time in a battery backup register */
 	secs += 1;
 	gpbr_writel(rtc, secs);

 	/* adjust the alarm time for the new base */
 	alarm = rtt_readl(rtc, AR);
 	if (alarm != ALARM_DISABLED) {
 		if (offset > secs) {
 			/* time jumped backwards, increase time until alarm */
 			alarm += (offset - secs);
 		} else if ((alarm + offset) > secs) {
 			/* time jumped forwards, decrease time until alarm */
 			alarm -= (secs - offset);
 		} else {
 			/* time jumped past the alarm, disable alarm */
 			alarm = ALARM_DISABLED;
 			mr &= ~AT91_RTT_ALMIEN;
 		}
 		rtt_writel(rtc, AR, alarm);
 	}

 	/* reset the timer, and re-enable interrupts */
 	rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);

 	return 0;
 }

 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &alrm->time;
 	u32 alarm = rtt_readl(rtc, AR);
 	u32 offset;

 	offset = gpbr_readl(rtc);
 	if (offset == 0)
 		return -EILSEQ;

 	memset(alrm, 0, sizeof(*alrm));
 	if (alarm != ALARM_DISABLED && offset != 0) {
 		rtc_time_to_tm(offset + alarm, tm);

 		dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
 			1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 			tm->tm_hour, tm->tm_min, tm->tm_sec);

 		if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
 			alrm->enabled = 1;
 	}

 	return 0;
 }

 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &alrm->time;
 	unsigned long secs;
 	u32 offset;
 	u32 mr;
 	int err;

 	err = rtc_tm_to_time(tm, &secs);
 	if (err != 0)
 		return err;

 	offset = gpbr_readl(rtc);
 	if (offset == 0) {
 		/* time is not set */
 		return -EILSEQ;
 	}
 	mr = rtt_readl(rtc, MR);
 	rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);

 	/* alarm in the past? finish and leave disabled */
 	if (secs <= offset) {
 		rtt_writel(rtc, AR, ALARM_DISABLED);
 		return 0;
 	}

 	/* else set alarm and maybe enable it */
 	rtt_writel(rtc, AR, secs - offset);
 	if (alrm->enabled)
 		rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);

 	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
 		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
 		tm->tm_min, tm->tm_sec);

 	return 0;
 }

 /*
  * Handle commands from user-space
  */
 static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
 			unsigned long arg)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	int ret = 0;
 	u32 mr = rtt_readl(rtc, MR);

 	dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);

 	switch (cmd) {
 	case RTC_AIE_OFF:		/* alarm off */
 		rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
 		break;
 	case RTC_AIE_ON:		/* alarm on */
 		rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
 		break;
 	case RTC_UIE_OFF:		/* update off */
 		rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
 		break;
 	case RTC_UIE_ON:		/* update on */
 		rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
 		break;
 	default:
 		ret = -ENOIOCTLCMD;
 		break;
 	}

 	return ret;
 }

 /*
  * Provide additional RTC information in /proc/driver/rtc
  */
 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
 	u32 mr = mr = rtt_readl(rtc, MR);

 	seq_printf(seq, "update_IRQ\t: %s\n",
 			(mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
 	return 0;
 }

 /*
  * IRQ handler for the RTC
  */
 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
 {
 	struct sam9_rtc *rtc = _rtc;
 	u32 sr, mr;
 	unsigned long events = 0;

 	/* Shared interrupt may be for another device.  Note: reading
 	 * SR clears it, so we must only read it in this irq handler!
 	 */
 	mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 	sr = rtt_readl(rtc, SR) & (mr >> 16);
 	if (!sr)
 		return IRQ_NONE;

 	/* alarm status */
 	if (sr & AT91_RTT_ALMS)
 		events |= (RTC_AF | RTC_IRQF);

 	/* timer update/increment */
 	if (sr & AT91_RTT_RTTINC)
 		events |= (RTC_UF | RTC_IRQF);

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

 	pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
 		events >> 8, events & 0x000000FF);

 	return IRQ_HANDLED;
 }

 static const struct rtc_class_ops at91_rtc_ops = {
 	.ioctl		= at91_rtc_ioctl,
 	.read_time	= at91_rtc_readtime,
 	.set_time	= at91_rtc_settime,
 	.read_alarm	= at91_rtc_readalarm,
 	.set_alarm	= at91_rtc_setalarm,
 	.proc		= at91_rtc_proc,
 };

 /*
  * Initialize and install RTC driver
  */
 static int __init at91_rtc_probe(struct platform_device *pdev)
 {
 	struct resource	*r;
 	struct sam9_rtc	*rtc;
 	int		ret;
 	u32		mr;

 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!r)
 		return -ENODEV;

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

 	/* platform setup code should have handled this; sigh */
 	if (!device_can_wakeup(&pdev->dev))
 		device_init_wakeup(&pdev->dev, 1);

 	platform_set_drvdata(pdev, rtc);
 	rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
 	rtc->rtt += r->start;

 	mr = rtt_readl(rtc, MR);

 	/* unless RTT is counting at 1 Hz, re-initialize it */
 	if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
 		mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
 		gpbr_writel(rtc, 0);
 	}

 	/* disable all interrupts (same as on shutdown path) */
 	mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 	rtt_writel(rtc, MR, mr);

 	rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
 				&at91_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc->rtcdev)) {
 		ret = PTR_ERR(rtc->rtcdev);
 		goto fail;
 	}

 	/* register irq handler after we know what name we'll use */
 	ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
 				IRQF_DISABLED | IRQF_SHARED,
 				dev_name(&rtc->rtcdev->dev), rtc);
 	if (ret) {
 		dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
 		rtc_device_unregister(rtc->rtcdev);
 		goto fail;
 	}

 	/* NOTE:  sam9260 rev A silicon has a ROM bug which resets the
 	 * RTT on at least some reboots.  If you have that chip, you must
 	 * initialize the time from some external source like a GPS, wall
 	 * clock, discrete RTC, etc
 	 */

 	if (gpbr_readl(rtc) == 0)
 		dev_warn(&pdev->dev, "%s: SET TIME!\n",
 				dev_name(&rtc->rtcdev->dev));

 	return 0;

 fail:
 	platform_set_drvdata(pdev, NULL);
 	kfree(rtc);
 	return ret;
 }

 /*
  * Disable and remove the RTC driver
  */
 static int __exit at91_rtc_remove(struct platform_device *pdev)
 {
 	struct sam9_rtc	*rtc = platform_get_drvdata(pdev);
 	u32		mr = rtt_readl(rtc, MR);

 	/* disable all interrupts */
 	rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
 	free_irq(AT91_ID_SYS, rtc);

 	rtc_device_unregister(rtc->rtcdev);

 	platform_set_drvdata(pdev, NULL);
 	kfree(rtc);
 	return 0;
 }

 static void at91_rtc_shutdown(struct platform_device *pdev)
 {
 	struct sam9_rtc	*rtc = platform_get_drvdata(pdev);
 	u32		mr = rtt_readl(rtc, MR);

 	rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 	rtt_writel(rtc, MR, mr & ~rtc->imr);
 }

 #ifdef CONFIG_PM

 /* AT91SAM9 RTC Power management control */

 static int at91_rtc_suspend(struct platform_device *pdev,
 					pm_message_t state)
 {
 	struct sam9_rtc	*rtc = platform_get_drvdata(pdev);
 	u32		mr = rtt_readl(rtc, MR);

 	/*
 	 * This IRQ is shared with DBGU and other hardware which isn't
 	 * necessarily a wakeup event source.
 	 */
 	rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 	if (rtc->imr) {
 		if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
 			enable_irq_wake(AT91_ID_SYS);
 			/* don't let RTTINC cause wakeups */
 			if (mr & AT91_RTT_RTTINCIEN)
 				rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
 		} else
 			rtt_writel(rtc, MR, mr & ~rtc->imr);
 	}

 	return 0;
 }

 static int at91_rtc_resume(struct platform_device *pdev)
 {
 	struct sam9_rtc	*rtc = platform_get_drvdata(pdev);
 	u32		mr;

 	if (rtc->imr) {
 		if (device_may_wakeup(&pdev->dev))
 			disable_irq_wake(AT91_ID_SYS);
 		mr = rtt_readl(rtc, MR);
 		rtt_writel(rtc, MR, mr | rtc->imr);
 	}

 	return 0;
 }
 #else
 #define at91_rtc_suspend	NULL
 #define at91_rtc_resume		NULL
 #endif

 static struct platform_driver at91_rtc_driver = {
 	.driver.name	= "rtc-at91sam9",
 	.driver.owner	= THIS_MODULE,
 	.remove		= __exit_p(at91_rtc_remove),
 	.shutdown	= at91_rtc_shutdown,
 	.suspend	= at91_rtc_suspend,
 	.resume		= at91_rtc_resume,
 };

 /* Chips can have more than one RTT module, and they can be used for more
  * than just RTCs.  So we can't just register as "the" RTT driver.
  *
  * A normal approach in such cases is to create a library to allocate and
  * free the modules.  Here we just use bus_find_device() as like such a
  * library, binding directly ... no runtime "library" footprint is needed.
  */
 static int __init at91_rtc_match(struct device *dev, void *v)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	int ret;

 	/* continue searching if this isn't the RTT we need */
 	if (strcmp("at91_rtt", pdev->name) != 0
 			|| pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
 		goto fail;

 	/* else we found it ... but fail unless we can bind to the RTC driver */
 	if (dev->driver) {
 		dev_dbg(dev, "busy, can't use as RTC!\n");
 		goto fail;
 	}
 	dev->driver = &at91_rtc_driver.driver;
 	if (device_attach(dev) == 0) {
 		dev_dbg(dev, "can't attach RTC!\n");
 		goto fail;
 	}
 	ret = at91_rtc_probe(pdev);
 	if (ret == 0)
 		return true;

 	dev_dbg(dev, "RTC probe err %d!\n", ret);
 fail:
 	return false;
 }

 static int __init at91_rtc_init(void)
 {
 	int status;
 	struct device *rtc;

 	status = platform_driver_register(&at91_rtc_driver);
 	if (status)
 		return status;
 	rtc = bus_find_device(&platform_bus_type, NULL,
 			NULL, at91_rtc_match);
 	if (!rtc)
 		platform_driver_unregister(&at91_rtc_driver);
 	return rtc ? 0 : -ENODEV;
 }
 module_init(at91_rtc_init);

 static void __exit at91_rtc_exit(void)
 {
 	platform_driver_unregister(&at91_rtc_driver);
 }
 module_exit(at91_rtc_exit);


 MODULE_AUTHOR("Michel Benoit");
 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
 MODULE_LICENSE("GPL");
	/*
	* "RTT as Real Time Clock" driver for AT91SAM9 SoC family
	*
	* (C) 2007 Michel Benoit
	*
	* Based on rtc-at91rm9200.c by Rick Bronson
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/platform_device.h>
	#include <linux/time.h>
	#include <linux/rtc.h>
	#include <linux/interrupt.h>
	#include <linux/ioctl.h>
	#include <linux/slab.h>

	#include <mach/board.h>
	#include <mach/at91_rtt.h>
	#include <mach/cpu.h>


	/*
	* This driver uses two configurable hardware resources that live in the
	* AT91SAM9 backup power domain (intended to be powered at all times)
	* to implement the Real Time Clock interfaces
	*
	* - A "Real-time Timer" (RTT) counts up in seconds from a base time.
	* We can't assign the counter value (CRTV) ... but we can reset it.
	*
	* - One of the "General Purpose Backup Registers" (GPBRs) holds the
	* base time, normally an offset from the beginning of the POSIX
	* epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the
	* local timezone's offset.
	*
	* The RTC's value is the RTT counter plus that offset. The RTC's alarm
	* is likewise a base (ALMV) plus that offset.
	*
	* Not all RTTs will be used as RTCs; some systems have multiple RTTs to
	* choose from, or a "real" RTC module. All systems have multiple GPBR
	* registers available, likewise usable for more than "RTC" support.
	*/

	/*
	* We store ALARM_DISABLED in ALMV to record that no alarm is set.
	* It's also the reset value for that field.
	*/
	#define ALARM_DISABLED ((u32)~0)


	struct sam9_rtc {
	void __iomem *rtt;
	struct rtc_device *rtcdev;
	u32 imr;
	};

	#define rtt_readl(rtc, field) \
	__raw_readl((rtc)->rtt + AT91_RTT_ ## field)
	#define rtt_writel(rtc, field, val) \
	__raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)

	#define gpbr_readl(rtc) \
	at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
	#define gpbr_writel(rtc, val) \
	at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))

	/*
	* Read current time and date in RTC
	*/
	static int at91_rtc_readtime(struct device dev, struct rtc_time tm)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	u32 secs, secs2;
	u32 offset;

	/* read current time offset */
	offset = gpbr_readl(rtc);
	if (offset == 0)
	return -EILSEQ;

	/* reread the counter to help sync the two clock domains */
	secs = rtt_readl(rtc, VR);
	secs2 = rtt_readl(rtc, VR);
	if (secs != secs2)
	secs = rtt_readl(rtc, VR);

	rtc_time_to_tm(offset + secs, tm);

	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
	1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
	tm->tm_hour, tm->tm_min, tm->tm_sec);

	return 0;
	}

	/*
	* Set current time and date in RTC
	*/
	static int at91_rtc_settime(struct device dev, struct rtc_time tm)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	int err;
	u32 offset, alarm, mr;
	unsigned long secs;

	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
	1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
	tm->tm_hour, tm->tm_min, tm->tm_sec);

	err = rtc_tm_to_time(tm, &secs);
	if (err != 0)
	return err;

	mr = rtt_readl(rtc, MR);

	/* disable interrupts */
	rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN));

	/* read current time offset */
	offset = gpbr_readl(rtc);

	/* store the new base time in a battery backup register */
	secs += 1;
	gpbr_writel(rtc, secs);

	/* adjust the alarm time for the new base */
	alarm = rtt_readl(rtc, AR);
	if (alarm != ALARM_DISABLED) {
	if (offset > secs) {
	/* time jumped backwards, increase time until alarm */
	alarm += (offset - secs);
	} else if ((alarm + offset) > secs) {
	/* time jumped forwards, decrease time until alarm */
	alarm -= (secs - offset);
	} else {
	/* time jumped past the alarm, disable alarm */
	alarm = ALARM_DISABLED;
	mr &= ~AT91_RTT_ALMIEN;
	}
	rtt_writel(rtc, AR, alarm);
	}

	/* reset the timer, and re-enable interrupts */
	rtt_writel(rtc, MR, mr \| AT91_RTT_RTTRST);

	return 0;
	}

	static int at91_rtc_readalarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time;
	u32 alarm = rtt_readl(rtc, AR);
	u32 offset;

	offset = gpbr_readl(rtc);
	if (offset == 0)
	return -EILSEQ;

	memset(alrm, 0, sizeof(*alrm));
	if (alarm != ALARM_DISABLED && offset != 0) {
	rtc_time_to_tm(offset + alarm, tm);

	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
	1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
	tm->tm_hour, tm->tm_min, tm->tm_sec);

	if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
	alrm->enabled = 1;
	}

	return 0;
	}

	static int at91_rtc_setalarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time;
	unsigned long secs;
	u32 offset;
	u32 mr;
	int err;

	err = rtc_tm_to_time(tm, &secs);
	if (err != 0)
	return err;

	offset = gpbr_readl(rtc);
	if (offset == 0) {
	/* time is not set */
	return -EILSEQ;
	}
	mr = rtt_readl(rtc, MR);
	rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);

	/* alarm in the past? finish and leave disabled */
	if (secs <= offset) {
	rtt_writel(rtc, AR, ALARM_DISABLED);
	return 0;
	}

	/* else set alarm and maybe enable it */
	rtt_writel(rtc, AR, secs - offset);
	if (alrm->enabled)
	rtt_writel(rtc, MR, mr \| AT91_RTT_ALMIEN);

	dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
	tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
	tm->tm_min, tm->tm_sec);

	return 0;
	}

	/*
	* Handle commands from user-space
	*/
	static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	int ret = 0;
	u32 mr = rtt_readl(rtc, MR);

	dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);

	switch (cmd) {
	case RTC_AIE_OFF: /* alarm off */
	rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
	break;
	case RTC_AIE_ON: /* alarm on */
	rtt_writel(rtc, MR, mr \| AT91_RTT_ALMIEN);
	break;
	case RTC_UIE_OFF: /* update off */
	rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
	break;
	case RTC_UIE_ON: /* update on */
	rtt_writel(rtc, MR, mr \| AT91_RTT_RTTINCIEN);
	break;
	default:
	ret = -ENOIOCTLCMD;
	break;
	}

	return ret;
	}

	/*
	* Provide additional RTC information in /proc/driver/rtc
	*/
	static int at91_rtc_proc(struct device dev, struct seq_file seq)
	{
	struct sam9_rtc *rtc = dev_get_drvdata(dev);
	u32 mr = mr = rtt_readl(rtc, MR);

	seq_printf(seq, "update_IRQ\t: %s\n",
	(mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
	return 0;
	}

	/*
	* IRQ handler for the RTC
	*/
	static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
	{
	struct sam9_rtc *rtc = _rtc;
	u32 sr, mr;
	unsigned long events = 0;

	/* Shared interrupt may be for another device. Note: reading
	* SR clears it, so we must only read it in this irq handler!
	*/
	mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN);
	sr = rtt_readl(rtc, SR) & (mr >> 16);
	if (!sr)
	return IRQ_NONE;

	/* alarm status */
	if (sr & AT91_RTT_ALMS)
	events \|= (RTC_AF \| RTC_IRQF);

	/* timer update/increment */
	if (sr & AT91_RTT_RTTINC)
	events \|= (RTC_UF \| RTC_IRQF);

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

	pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
	events >> 8, events & 0x000000FF);

	return IRQ_HANDLED;
	}

	static const struct rtc_class_ops at91_rtc_ops = {
	.ioctl = at91_rtc_ioctl,
	.read_time = at91_rtc_readtime,
	.set_time = at91_rtc_settime,
	.read_alarm = at91_rtc_readalarm,
	.set_alarm = at91_rtc_setalarm,
	.proc = at91_rtc_proc,
	};

	/*
	* Initialize and install RTC driver
	*/
	static int __init at91_rtc_probe(struct platform_device *pdev)
	{
	struct resource *r;
	struct sam9_rtc *rtc;
	int ret;
	u32 mr;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!r)
	return -ENODEV;

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

	/* platform setup code should have handled this; sigh */
	if (!device_can_wakeup(&pdev->dev))
	device_init_wakeup(&pdev->dev, 1);

	platform_set_drvdata(pdev, rtc);
	rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
	rtc->rtt += r->start;

	mr = rtt_readl(rtc, MR);

	/* unless RTT is counting at 1 Hz, re-initialize it */
	if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
	mr = AT91_RTT_RTTRST \| (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
	gpbr_writel(rtc, 0);
	}

	/* disable all interrupts (same as on shutdown path) */
	mr &= ~(AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN);
	rtt_writel(rtc, MR, mr);

	rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
	&at91_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc->rtcdev)) {
	ret = PTR_ERR(rtc->rtcdev);
	goto fail;
	}

	/* register irq handler after we know what name we'll use */
	ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
	IRQF_DISABLED \| IRQF_SHARED,
	dev_name(&rtc->rtcdev->dev), rtc);
	if (ret) {
	dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
	rtc_device_unregister(rtc->rtcdev);
	goto fail;
	}

	/* NOTE: sam9260 rev A silicon has a ROM bug which resets the
	* RTT on at least some reboots. If you have that chip, you must
	* initialize the time from some external source like a GPS, wall
	* clock, discrete RTC, etc
	*/

	if (gpbr_readl(rtc) == 0)
	dev_warn(&pdev->dev, "%s: SET TIME!\n",
	dev_name(&rtc->rtcdev->dev));

	return 0;

	fail:
	platform_set_drvdata(pdev, NULL);
	kfree(rtc);
	return ret;
	}

	/*
	* Disable and remove the RTC driver
	*/
	static int __exit at91_rtc_remove(struct platform_device *pdev)
	{
	struct sam9_rtc *rtc = platform_get_drvdata(pdev);
	u32 mr = rtt_readl(rtc, MR);

	/* disable all interrupts */
	rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN));
	free_irq(AT91_ID_SYS, rtc);

	rtc_device_unregister(rtc->rtcdev);

	platform_set_drvdata(pdev, NULL);
	kfree(rtc);
	return 0;
	}

	static void at91_rtc_shutdown(struct platform_device *pdev)
	{
	struct sam9_rtc *rtc = platform_get_drvdata(pdev);
	u32 mr = rtt_readl(rtc, MR);

	rtc->imr = mr & (AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN);
	rtt_writel(rtc, MR, mr & ~rtc->imr);
	}

	#ifdef CONFIG_PM

	/* AT91SAM9 RTC Power management control */

	static int at91_rtc_suspend(struct platform_device *pdev,
	pm_message_t state)
	{
	struct sam9_rtc *rtc = platform_get_drvdata(pdev);
	u32 mr = rtt_readl(rtc, MR);

	/*
	* This IRQ is shared with DBGU and other hardware which isn't
	* necessarily a wakeup event source.
	*/
	rtc->imr = mr & (AT91_RTT_ALMIEN \| AT91_RTT_RTTINCIEN);
	if (rtc->imr) {
	if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
	enable_irq_wake(AT91_ID_SYS);
	/* don't let RTTINC cause wakeups */
	if (mr & AT91_RTT_RTTINCIEN)
	rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
	} else
	rtt_writel(rtc, MR, mr & ~rtc->imr);
	}

	return 0;
	}

	static int at91_rtc_resume(struct platform_device *pdev)
	{
	struct sam9_rtc *rtc = platform_get_drvdata(pdev);
	u32 mr;

	if (rtc->imr) {
	if (device_may_wakeup(&pdev->dev))
	disable_irq_wake(AT91_ID_SYS);
	mr = rtt_readl(rtc, MR);
	rtt_writel(rtc, MR, mr \| rtc->imr);
	}

	return 0;
	}
	#else
	#define at91_rtc_suspend NULL
	#define at91_rtc_resume NULL
	#endif

	static struct platform_driver at91_rtc_driver = {
	.driver.name = "rtc-at91sam9",
	.driver.owner = THIS_MODULE,
	.remove = __exit_p(at91_rtc_remove),
	.shutdown = at91_rtc_shutdown,
	.suspend = at91_rtc_suspend,
	.resume = at91_rtc_resume,
	};

	/* Chips can have more than one RTT module, and they can be used for more
	* than just RTCs. So we can't just register as "the" RTT driver.
	*
	* A normal approach in such cases is to create a library to allocate and
	* free the modules. Here we just use bus_find_device() as like such a
	* library, binding directly ... no runtime "library" footprint is needed.
	*/
	static int __init at91_rtc_match(struct device dev, void v)
	{
	struct platform_device *pdev = to_platform_device(dev);
	int ret;

	/* continue searching if this isn't the RTT we need */
	if (strcmp("at91_rtt", pdev->name) != 0
	\|\| pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
	goto fail;

	/* else we found it ... but fail unless we can bind to the RTC driver */
	if (dev->driver) {
	dev_dbg(dev, "busy, can't use as RTC!\n");
	goto fail;
	}
	dev->driver = &at91_rtc_driver.driver;
	if (device_attach(dev) == 0) {
	dev_dbg(dev, "can't attach RTC!\n");
	goto fail;
	}
	ret = at91_rtc_probe(pdev);
	if (ret == 0)
	return true;

	dev_dbg(dev, "RTC probe err %d!\n", ret);
	fail:
	return false;
	}

	static int __init at91_rtc_init(void)
	{
	int status;
	struct device *rtc;

	status = platform_driver_register(&at91_rtc_driver);
	if (status)
	return status;
	rtc = bus_find_device(&platform_bus_type, NULL,
	NULL, at91_rtc_match);
	if (!rtc)
	platform_driver_unregister(&at91_rtc_driver);
	return rtc ? 0 : -ENODEV;
	}
	module_init(at91_rtc_init);

	static void __exit at91_rtc_exit(void)
	{
	platform_driver_unregister(&at91_rtc_driver);
	}
	module_exit(at91_rtc_exit);


	MODULE_AUTHOR("Michel Benoit");
	MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
	MODULE_LICENSE("GPL");