drivers/rtc/rtc-at91rm9200.c - maze/linux - Git at Google

 /*
  *	Real Time Clock interface for Linux on Atmel AT91RM9200
  *
  *	Copyright (C) 2002 Rick Bronson
  *
  *	Converted to RTC class model by Andrew Victor
  *
  *	Ported to Linux 2.6 by Steven Scholz
  *	Based on s3c2410-rtc.c Simtec Electronics
  *
  *	Based on sa1100-rtc.c by Nils Faerber
  *	Based on rtc.c by Paul Gortmaker
  *
  *	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/bcd.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/ioctl.h>
 #include <linux/completion.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/uaccess.h>

 #include "rtc-at91rm9200.h"

 #define at91_rtc_read(field) \
 	__raw_readl(at91_rtc_regs + field)
 #define at91_rtc_write(field, val) \
 	__raw_writel((val), at91_rtc_regs + field)

 #define AT91_RTC_EPOCH		1900UL	/* just like arch/arm/common/rtctime.c */

 struct at91_rtc_config {
 	bool use_shadow_imr;
 };

 static const struct at91_rtc_config *at91_rtc_config;
 static DECLARE_COMPLETION(at91_rtc_updated);
 static unsigned int at91_alarm_year = AT91_RTC_EPOCH;
 static void __iomem *at91_rtc_regs;
 static int irq;
 static DEFINE_SPINLOCK(at91_rtc_lock);
 static u32 at91_rtc_shadow_imr;

 static void at91_rtc_write_ier(u32 mask)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&at91_rtc_lock, flags);
 	at91_rtc_shadow_imr |= mask;
 	at91_rtc_write(AT91_RTC_IER, mask);
 	spin_unlock_irqrestore(&at91_rtc_lock, flags);
 }

 static void at91_rtc_write_idr(u32 mask)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&at91_rtc_lock, flags);
 	at91_rtc_write(AT91_RTC_IDR, mask);
 	/*
 	 * Register read back (of any RTC-register) needed to make sure
 	 * IDR-register write has reached the peripheral before updating
 	 * shadow mask.
 	 *
 	 * Note that there is still a possibility that the mask is updated
 	 * before interrupts have actually been disabled in hardware. The only
 	 * way to be certain would be to poll the IMR-register, which is is
 	 * the very register we are trying to emulate. The register read back
 	 * is a reasonable heuristic.
 	 */
 	at91_rtc_read(AT91_RTC_SR);
 	at91_rtc_shadow_imr &= ~mask;
 	spin_unlock_irqrestore(&at91_rtc_lock, flags);
 }

 static u32 at91_rtc_read_imr(void)
 {
 	unsigned long flags;
 	u32 mask;

 	if (at91_rtc_config->use_shadow_imr) {
 		spin_lock_irqsave(&at91_rtc_lock, flags);
 		mask = at91_rtc_shadow_imr;
 		spin_unlock_irqrestore(&at91_rtc_lock, flags);
 	} else {
 		mask = at91_rtc_read(AT91_RTC_IMR);
 	}

 	return mask;
 }

 /*
  * Decode time/date into rtc_time structure
  */
 static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
 				struct rtc_time *tm)
 {
 	unsigned int time, date;

 	/* must read twice in case it changes */
 	do {
 		time = at91_rtc_read(timereg);
 		date = at91_rtc_read(calreg);
 	} while ((time != at91_rtc_read(timereg)) ||
 			(date != at91_rtc_read(calreg)));

 	tm->tm_sec  = bcd2bin((time & AT91_RTC_SEC) >> 0);
 	tm->tm_min  = bcd2bin((time & AT91_RTC_MIN) >> 8);
 	tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);

 	/*
 	 * The Calendar Alarm register does not have a field for
 	 * the year - so these will return an invalid value.  When an
 	 * alarm is set, at91_alarm_year will store the current year.
 	 */
 	tm->tm_year  = bcd2bin(date & AT91_RTC_CENT) * 100;	/* century */
 	tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8);	/* year */

 	tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1;	/* day of the week [0-6], Sunday=0 */
 	tm->tm_mon  = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
 	tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);
 }

 /*
  * Read current time and date in RTC
  */
 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
 {
 	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
 	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
 	tm->tm_year = tm->tm_year - 1900;

 	dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
 		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)
 {
 	unsigned long cr;

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

 	/* Stop Time/Calendar from counting */
 	cr = at91_rtc_read(AT91_RTC_CR);
 	at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);

 	at91_rtc_write_ier(AT91_RTC_ACKUPD);
 	wait_for_completion(&at91_rtc_updated);	/* wait for ACKUPD interrupt */
 	at91_rtc_write_idr(AT91_RTC_ACKUPD);

 	at91_rtc_write(AT91_RTC_TIMR,
 			  bin2bcd(tm->tm_sec) << 0
 			| bin2bcd(tm->tm_min) << 8
 			| bin2bcd(tm->tm_hour) << 16);

 	at91_rtc_write(AT91_RTC_CALR,
 			  bin2bcd((tm->tm_year + 1900) / 100)	/* century */
 			| bin2bcd(tm->tm_year % 100) << 8	/* year */
 			| bin2bcd(tm->tm_mon + 1) << 16		/* tm_mon starts at zero */
 			| bin2bcd(tm->tm_wday + 1) << 21	/* day of the week [0-6], Sunday=0 */
 			| bin2bcd(tm->tm_mday) << 24);

 	/* Restart Time/Calendar */
 	cr = at91_rtc_read(AT91_RTC_CR);
 	at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));

 	return 0;
 }

 /*
  * Read alarm time and date in RTC
  */
 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rtc_time *tm = &alrm->time;

 	at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
 	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
 	tm->tm_year = at91_alarm_year - 1900;

 	alrm->enabled = (at91_rtc_read_imr() & AT91_RTC_ALARM)
 			? 1 : 0;

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

 	return 0;
 }

 /*
  * Set alarm time and date in RTC
  */
 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rtc_time tm;

 	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);

 	at91_alarm_year = tm.tm_year;

 	tm.tm_hour = alrm->time.tm_hour;
 	tm.tm_min = alrm->time.tm_min;
 	tm.tm_sec = alrm->time.tm_sec;

 	at91_rtc_write_idr(AT91_RTC_ALARM);
 	at91_rtc_write(AT91_RTC_TIMALR,
 		  bin2bcd(tm.tm_sec) << 0
 		| bin2bcd(tm.tm_min) << 8
 		| bin2bcd(tm.tm_hour) << 16
 		| AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
 	at91_rtc_write(AT91_RTC_CALALR,
 		  bin2bcd(tm.tm_mon + 1) << 16		/* tm_mon starts at zero */
 		| bin2bcd(tm.tm_mday) << 24
 		| AT91_RTC_DATEEN | AT91_RTC_MTHEN);

 	if (alrm->enabled) {
 		at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
 		at91_rtc_write_ier(AT91_RTC_ALARM);
 	}

 	dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
 		at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
 		tm.tm_min, tm.tm_sec);

 	return 0;
 }

 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);

 	if (enabled) {
 		at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
 		at91_rtc_write_ier(AT91_RTC_ALARM);
 	} else
 		at91_rtc_write_idr(AT91_RTC_ALARM);

 	return 0;
 }
 /*
  * Provide additional RTC information in /proc/driver/rtc
  */
 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 	unsigned long imr = at91_rtc_read_imr();

 	seq_printf(seq, "update_IRQ\t: %s\n",
 			(imr & AT91_RTC_ACKUPD) ? "yes" : "no");
 	seq_printf(seq, "periodic_IRQ\t: %s\n",
 			(imr & AT91_RTC_SECEV) ? "yes" : "no");

 	return 0;
 }

 /*
  * IRQ handler for the RTC
  */
 static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = dev_id;
 	struct rtc_device *rtc = platform_get_drvdata(pdev);
 	unsigned int rtsr;
 	unsigned long events = 0;

 	rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
 	if (rtsr) {		/* this interrupt is shared!  Is it ours? */
 		if (rtsr & AT91_RTC_ALARM)
 			events |= (RTC_AF | RTC_IRQF);
 		if (rtsr & AT91_RTC_SECEV)
 			events |= (RTC_UF | RTC_IRQF);
 		if (rtsr & AT91_RTC_ACKUPD)
 			complete(&at91_rtc_updated);

 		at91_rtc_write(AT91_RTC_SCCR, rtsr);	/* clear status reg */

 		rtc_update_irq(rtc, 1, events);

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

 		return IRQ_HANDLED;
 	}
 	return IRQ_NONE;		/* not handled */
 }

 static const struct at91_rtc_config at91rm9200_config = {
 };

 static const struct at91_rtc_config at91sam9x5_config = {
 	.use_shadow_imr	= true,
 };

 #ifdef CONFIG_OF
 static const struct of_device_id at91_rtc_dt_ids[] = {
 	{
 		.compatible = "atmel,at91rm9200-rtc",
 		.data = &at91rm9200_config,
 	}, {
 		.compatible = "atmel,at91sam9x5-rtc",
 		.data = &at91sam9x5_config,
 	}, {
 		/* sentinel */
 	}
 };
 MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
 #endif

 static const struct at91_rtc_config *
 at91_rtc_get_config(struct platform_device *pdev)
 {
 	const struct of_device_id *match;

 	if (pdev->dev.of_node) {
 		match = of_match_node(at91_rtc_dt_ids, pdev->dev.of_node);
 		if (!match)
 			return NULL;
 		return (const struct at91_rtc_config *)match->data;
 	}

 	return &at91rm9200_config;
 }

 static const struct rtc_class_ops at91_rtc_ops = {
 	.read_time	= at91_rtc_readtime,
 	.set_time	= at91_rtc_settime,
 	.read_alarm	= at91_rtc_readalarm,
 	.set_alarm	= at91_rtc_setalarm,
 	.proc		= at91_rtc_proc,
 	.alarm_irq_enable = at91_rtc_alarm_irq_enable,
 };

 /*
  * Initialize and install RTC driver
  */
 static int __init at91_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 	struct resource *regs;
 	int ret = 0;

 	at91_rtc_config = at91_rtc_get_config(pdev);
 	if (!at91_rtc_config)
 		return -ENODEV;

 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!regs) {
 		dev_err(&pdev->dev, "no mmio resource defined\n");
 		return -ENXIO;
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(&pdev->dev, "no irq resource defined\n");
 		return -ENXIO;
 	}

 	at91_rtc_regs = devm_ioremap(&pdev->dev, regs->start,
 				     resource_size(regs));
 	if (!at91_rtc_regs) {
 		dev_err(&pdev->dev, "failed to map registers, aborting.\n");
 		return -ENOMEM;
 	}

 	at91_rtc_write(AT91_RTC_CR, 0);
 	at91_rtc_write(AT91_RTC_MR, 0);		/* 24 hour mode */

 	/* Disable all interrupts */
 	at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
 					AT91_RTC_SECEV | AT91_RTC_TIMEV |
 					AT91_RTC_CALEV);

 	ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
 				IRQF_SHARED,
 				"at91_rtc", pdev);
 	if (ret) {
 		dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
 		return ret;
 	}

 	/* cpu init code should really have flagged this device as
 	 * being wake-capable; if it didn't, do that here.
 	 */
 	if (!device_can_wakeup(&pdev->dev))
 		device_init_wakeup(&pdev->dev, 1);

 	rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 				&at91_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 	platform_set_drvdata(pdev, rtc);

 	dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
 	return 0;
 }

 /*
  * Disable and remove the RTC driver
  */
 static int __exit at91_rtc_remove(struct platform_device *pdev)
 {
 	/* Disable all interrupts */
 	at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
 					AT91_RTC_SECEV | AT91_RTC_TIMEV |
 					AT91_RTC_CALEV);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP

 /* AT91RM9200 RTC Power management control */

 static u32 at91_rtc_imr;

 static int at91_rtc_suspend(struct device *dev)
 {
 	/* this IRQ is shared with DBGU and other hardware which isn't
 	 * necessarily doing PM like we are...
 	 */
 	at91_rtc_imr = at91_rtc_read_imr()
 			& (AT91_RTC_ALARM|AT91_RTC_SECEV);
 	if (at91_rtc_imr) {
 		if (device_may_wakeup(dev))
 			enable_irq_wake(irq);
 		else
 			at91_rtc_write_idr(at91_rtc_imr);
 	}
 	return 0;
 }

 static int at91_rtc_resume(struct device *dev)
 {
 	if (at91_rtc_imr) {
 		if (device_may_wakeup(dev))
 			disable_irq_wake(irq);
 		else
 			at91_rtc_write_ier(at91_rtc_imr);
 	}
 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);

 static struct platform_driver at91_rtc_driver = {
 	.remove		= __exit_p(at91_rtc_remove),
 	.driver		= {
 		.name	= "at91_rtc",
 		.owner	= THIS_MODULE,
 		.pm	= &at91_rtc_pm_ops,
 		.of_match_table = of_match_ptr(at91_rtc_dt_ids),
 	},
 };

 module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);

 MODULE_AUTHOR("Rick Bronson");
 MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:at91_rtc");
	/*
	* Real Time Clock interface for Linux on Atmel AT91RM9200
	*
	* Copyright (C) 2002 Rick Bronson
	*
	* Converted to RTC class model by Andrew Victor
	*
	* Ported to Linux 2.6 by Steven Scholz
	* Based on s3c2410-rtc.c Simtec Electronics
	*
	* Based on sa1100-rtc.c by Nils Faerber
	* Based on rtc.c by Paul Gortmaker
	*
	* 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/bcd.h>
	#include <linux/interrupt.h>
	#include <linux/spinlock.h>
	#include <linux/ioctl.h>
	#include <linux/completion.h>
	#include <linux/io.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/uaccess.h>

	#include "rtc-at91rm9200.h"

	#define at91_rtc_read(field) \
	__raw_readl(at91_rtc_regs + field)
	#define at91_rtc_write(field, val) \
	__raw_writel((val), at91_rtc_regs + field)

	#define AT91_RTC_EPOCH 1900UL /* just like arch/arm/common/rtctime.c */

	struct at91_rtc_config {
	bool use_shadow_imr;
	};

	static const struct at91_rtc_config *at91_rtc_config;
	static DECLARE_COMPLETION(at91_rtc_updated);
	static unsigned int at91_alarm_year = AT91_RTC_EPOCH;
	static void __iomem *at91_rtc_regs;
	static int irq;
	static DEFINE_SPINLOCK(at91_rtc_lock);
	static u32 at91_rtc_shadow_imr;

	static void at91_rtc_write_ier(u32 mask)
	{
	unsigned long flags;

	spin_lock_irqsave(&at91_rtc_lock, flags);
	at91_rtc_shadow_imr \|= mask;
	at91_rtc_write(AT91_RTC_IER, mask);
	spin_unlock_irqrestore(&at91_rtc_lock, flags);
	}

	static void at91_rtc_write_idr(u32 mask)
	{
	unsigned long flags;

	spin_lock_irqsave(&at91_rtc_lock, flags);
	at91_rtc_write(AT91_RTC_IDR, mask);
	/*
	* Register read back (of any RTC-register) needed to make sure
	* IDR-register write has reached the peripheral before updating
	* shadow mask.
	*
	* Note that there is still a possibility that the mask is updated
	* before interrupts have actually been disabled in hardware. The only
	* way to be certain would be to poll the IMR-register, which is is
	* the very register we are trying to emulate. The register read back
	* is a reasonable heuristic.
	*/
	at91_rtc_read(AT91_RTC_SR);
	at91_rtc_shadow_imr &= ~mask;
	spin_unlock_irqrestore(&at91_rtc_lock, flags);
	}

	static u32 at91_rtc_read_imr(void)
	{
	unsigned long flags;
	u32 mask;

	if (at91_rtc_config->use_shadow_imr) {
	spin_lock_irqsave(&at91_rtc_lock, flags);
	mask = at91_rtc_shadow_imr;
	spin_unlock_irqrestore(&at91_rtc_lock, flags);
	} else {
	mask = at91_rtc_read(AT91_RTC_IMR);
	}

	return mask;
	}

	/*
	* Decode time/date into rtc_time structure
	*/
	static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
	struct rtc_time *tm)
	{
	unsigned int time, date;

	/* must read twice in case it changes */
	do {
	time = at91_rtc_read(timereg);
	date = at91_rtc_read(calreg);
	} while ((time != at91_rtc_read(timereg)) \|\|
	(date != at91_rtc_read(calreg)));

	tm->tm_sec = bcd2bin((time & AT91_RTC_SEC) >> 0);
	tm->tm_min = bcd2bin((time & AT91_RTC_MIN) >> 8);
	tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);

	/*
	* The Calendar Alarm register does not have a field for
	* the year - so these will return an invalid value. When an
	* alarm is set, at91_alarm_year will store the current year.
	*/
	tm->tm_year = bcd2bin(date & AT91_RTC_CENT) * 100; /* century */
	tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8); /* year */

	tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1; /* day of the week [0-6], Sunday=0 */
	tm->tm_mon = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
	tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);
	}

	/*
	* Read current time and date in RTC
	*/
	static int at91_rtc_readtime(struct device dev, struct rtc_time tm)
	{
	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
	tm->tm_year = tm->tm_year - 1900;

	dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
	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)
	{
	unsigned long cr;

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

	/* Stop Time/Calendar from counting */
	cr = at91_rtc_read(AT91_RTC_CR);
	at91_rtc_write(AT91_RTC_CR, cr \| AT91_RTC_UPDCAL \| AT91_RTC_UPDTIM);

	at91_rtc_write_ier(AT91_RTC_ACKUPD);
	wait_for_completion(&at91_rtc_updated); /* wait for ACKUPD interrupt */
	at91_rtc_write_idr(AT91_RTC_ACKUPD);

	at91_rtc_write(AT91_RTC_TIMR,
	bin2bcd(tm->tm_sec) << 0
	\| bin2bcd(tm->tm_min) << 8
	\| bin2bcd(tm->tm_hour) << 16);

	at91_rtc_write(AT91_RTC_CALR,
	bin2bcd((tm->tm_year + 1900) / 100) /* century */
	\| bin2bcd(tm->tm_year % 100) << 8 /* year */
	\| bin2bcd(tm->tm_mon + 1) << 16 /* tm_mon starts at zero */
	\| bin2bcd(tm->tm_wday + 1) << 21 /* day of the week [0-6], Sunday=0 */
	\| bin2bcd(tm->tm_mday) << 24);

	/* Restart Time/Calendar */
	cr = at91_rtc_read(AT91_RTC_CR);
	at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL \| AT91_RTC_UPDTIM));

	return 0;
	}

	/*
	* Read alarm time and date in RTC
	*/
	static int at91_rtc_readalarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rtc_time *tm = &alrm->time;

	at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
	tm->tm_year = at91_alarm_year - 1900;

	alrm->enabled = (at91_rtc_read_imr() & AT91_RTC_ALARM)
	? 1 : 0;

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

	return 0;
	}

	/*
	* Set alarm time and date in RTC
	*/
	static int at91_rtc_setalarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rtc_time tm;

	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);

	at91_alarm_year = tm.tm_year;

	tm.tm_hour = alrm->time.tm_hour;
	tm.tm_min = alrm->time.tm_min;
	tm.tm_sec = alrm->time.tm_sec;

	at91_rtc_write_idr(AT91_RTC_ALARM);
	at91_rtc_write(AT91_RTC_TIMALR,
	bin2bcd(tm.tm_sec) << 0
	\| bin2bcd(tm.tm_min) << 8
	\| bin2bcd(tm.tm_hour) << 16
	\| AT91_RTC_HOUREN \| AT91_RTC_MINEN \| AT91_RTC_SECEN);
	at91_rtc_write(AT91_RTC_CALALR,
	bin2bcd(tm.tm_mon + 1) << 16 /* tm_mon starts at zero */
	\| bin2bcd(tm.tm_mday) << 24
	\| AT91_RTC_DATEEN \| AT91_RTC_MTHEN);

	if (alrm->enabled) {
	at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
	at91_rtc_write_ier(AT91_RTC_ALARM);
	}

	dev_dbg(dev, "%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
	at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
	tm.tm_min, tm.tm_sec);

	return 0;
	}

	static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);

	if (enabled) {
	at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
	at91_rtc_write_ier(AT91_RTC_ALARM);
	} else
	at91_rtc_write_idr(AT91_RTC_ALARM);

	return 0;
	}
	/*
	* Provide additional RTC information in /proc/driver/rtc
	*/
	static int at91_rtc_proc(struct device dev, struct seq_file seq)
	{
	unsigned long imr = at91_rtc_read_imr();

	seq_printf(seq, "update_IRQ\t: %s\n",
	(imr & AT91_RTC_ACKUPD) ? "yes" : "no");
	seq_printf(seq, "periodic_IRQ\t: %s\n",
	(imr & AT91_RTC_SECEV) ? "yes" : "no");

	return 0;
	}

	/*
	* IRQ handler for the RTC
	*/
	static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
	{
	struct platform_device *pdev = dev_id;
	struct rtc_device *rtc = platform_get_drvdata(pdev);
	unsigned int rtsr;
	unsigned long events = 0;

	rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
	if (rtsr) { /* this interrupt is shared! Is it ours? */
	if (rtsr & AT91_RTC_ALARM)
	events \|= (RTC_AF \| RTC_IRQF);
	if (rtsr & AT91_RTC_SECEV)
	events \|= (RTC_UF \| RTC_IRQF);
	if (rtsr & AT91_RTC_ACKUPD)
	complete(&at91_rtc_updated);

	at91_rtc_write(AT91_RTC_SCCR, rtsr); /* clear status reg */

	rtc_update_irq(rtc, 1, events);

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

	return IRQ_HANDLED;
	}
	return IRQ_NONE; /* not handled */
	}

	static const struct at91_rtc_config at91rm9200_config = {
	};

	static const struct at91_rtc_config at91sam9x5_config = {
	.use_shadow_imr = true,
	};

	#ifdef CONFIG_OF
	static const struct of_device_id at91_rtc_dt_ids[] = {
	{
	.compatible = "atmel,at91rm9200-rtc",
	.data = &at91rm9200_config,
	}, {
	.compatible = "atmel,at91sam9x5-rtc",
	.data = &at91sam9x5_config,
	}, {
	/* sentinel */
	}
	};
	MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
	#endif

	static const struct at91_rtc_config *
	at91_rtc_get_config(struct platform_device *pdev)
	{
	const struct of_device_id *match;

	if (pdev->dev.of_node) {
	match = of_match_node(at91_rtc_dt_ids, pdev->dev.of_node);
	if (!match)
	return NULL;
	return (const struct at91_rtc_config *)match->data;
	}

	return &at91rm9200_config;
	}

	static const struct rtc_class_ops at91_rtc_ops = {
	.read_time = at91_rtc_readtime,
	.set_time = at91_rtc_settime,
	.read_alarm = at91_rtc_readalarm,
	.set_alarm = at91_rtc_setalarm,
	.proc = at91_rtc_proc,
	.alarm_irq_enable = at91_rtc_alarm_irq_enable,
	};

	/*
	* Initialize and install RTC driver
	*/
	static int __init at91_rtc_probe(struct platform_device *pdev)
	{
	struct rtc_device *rtc;
	struct resource *regs;
	int ret = 0;

	at91_rtc_config = at91_rtc_get_config(pdev);
	if (!at91_rtc_config)
	return -ENODEV;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs) {
	dev_err(&pdev->dev, "no mmio resource defined\n");
	return -ENXIO;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(&pdev->dev, "no irq resource defined\n");
	return -ENXIO;
	}

	at91_rtc_regs = devm_ioremap(&pdev->dev, regs->start,
	resource_size(regs));
	if (!at91_rtc_regs) {
	dev_err(&pdev->dev, "failed to map registers, aborting.\n");
	return -ENOMEM;
	}

	at91_rtc_write(AT91_RTC_CR, 0);
	at91_rtc_write(AT91_RTC_MR, 0); /* 24 hour mode */

	/* Disable all interrupts */
	at91_rtc_write_idr(AT91_RTC_ACKUPD \| AT91_RTC_ALARM \|
	AT91_RTC_SECEV \| AT91_RTC_TIMEV \|
	AT91_RTC_CALEV);

	ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
	IRQF_SHARED,
	"at91_rtc", pdev);
	if (ret) {
	dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
	return ret;
	}

	/* cpu init code should really have flagged this device as
	* being wake-capable; if it didn't, do that here.
	*/
	if (!device_can_wakeup(&pdev->dev))
	device_init_wakeup(&pdev->dev, 1);

	rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
	&at91_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);
	platform_set_drvdata(pdev, rtc);

	dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
	return 0;
	}

	/*
	* Disable and remove the RTC driver
	*/
	static int __exit at91_rtc_remove(struct platform_device *pdev)
	{
	/* Disable all interrupts */
	at91_rtc_write_idr(AT91_RTC_ACKUPD \| AT91_RTC_ALARM \|
	AT91_RTC_SECEV \| AT91_RTC_TIMEV \|
	AT91_RTC_CALEV);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP

	/* AT91RM9200 RTC Power management control */

	static u32 at91_rtc_imr;

	static int at91_rtc_suspend(struct device *dev)
	{
	/* this IRQ is shared with DBGU and other hardware which isn't
	* necessarily doing PM like we are...
	*/
	at91_rtc_imr = at91_rtc_read_imr()
	& (AT91_RTC_ALARM\|AT91_RTC_SECEV);
	if (at91_rtc_imr) {
	if (device_may_wakeup(dev))
	enable_irq_wake(irq);
	else
	at91_rtc_write_idr(at91_rtc_imr);
	}
	return 0;
	}

	static int at91_rtc_resume(struct device *dev)
	{
	if (at91_rtc_imr) {
	if (device_may_wakeup(dev))
	disable_irq_wake(irq);
	else
	at91_rtc_write_ier(at91_rtc_imr);
	}
	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);

	static struct platform_driver at91_rtc_driver = {
	.remove = __exit_p(at91_rtc_remove),
	.driver = {
	.name = "at91_rtc",
	.owner = THIS_MODULE,
	.pm = &at91_rtc_pm_ops,
	.of_match_table = of_match_ptr(at91_rtc_dt_ids),
	},
	};

	module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);

	MODULE_AUTHOR("Rick Bronson");
	MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:at91_rtc");