drivers/rtc/rtc-spear.c - linux/kernel/git/davem/net - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * drivers/rtc/rtc-spear.c
  *
  * Copyright (C) 2010 ST Microelectronics
  * Rajeev Kumar<rajeev-dlh.kumar@st.com>
  */

 #include <linux/bcd.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>

 /* RTC registers */
 #define TIME_REG		0x00
 #define DATE_REG		0x04
 #define ALARM_TIME_REG		0x08
 #define ALARM_DATE_REG		0x0C
 #define CTRL_REG		0x10
 #define STATUS_REG		0x14

 /* TIME_REG & ALARM_TIME_REG */
 #define SECONDS_UNITS		(0xf<<0)	/* seconds units position */
 #define SECONDS_TENS		(0x7<<4)	/* seconds tens position */
 #define MINUTES_UNITS		(0xf<<8)	/* minutes units position */
 #define MINUTES_TENS		(0x7<<12)	/* minutes tens position */
 #define HOURS_UNITS		(0xf<<16)	/* hours units position */
 #define HOURS_TENS		(0x3<<20)	/* hours tens position */

 /* DATE_REG & ALARM_DATE_REG */
 #define DAYS_UNITS		(0xf<<0)	/* days units position */
 #define DAYS_TENS		(0x3<<4)	/* days tens position */
 #define MONTHS_UNITS		(0xf<<8)	/* months units position */
 #define MONTHS_TENS		(0x1<<12)	/* months tens position */
 #define YEARS_UNITS		(0xf<<16)	/* years units position */
 #define YEARS_TENS		(0xf<<20)	/* years tens position */
 #define YEARS_HUNDREDS		(0xf<<24)	/* years hundereds position */
 #define YEARS_MILLENIUMS	(0xf<<28)	/* years millenium position */

 /* MASK SHIFT TIME_REG & ALARM_TIME_REG*/
 #define SECOND_SHIFT		0x00		/* seconds units */
 #define MINUTE_SHIFT		0x08		/* minutes units position */
 #define HOUR_SHIFT		0x10		/* hours units position */
 #define MDAY_SHIFT		0x00		/* Month day shift */
 #define MONTH_SHIFT		0x08		/* Month shift */
 #define YEAR_SHIFT		0x10		/* Year shift */

 #define SECOND_MASK		0x7F
 #define MIN_MASK		0x7F
 #define HOUR_MASK		0x3F
 #define DAY_MASK		0x3F
 #define MONTH_MASK		0x7F
 #define YEAR_MASK		0xFFFF

 /* date reg equal to time reg, for debug only */
 #define TIME_BYP		(1<<9)
 #define INT_ENABLE		(1<<31)		/* interrupt enable */

 /* STATUS_REG */
 #define CLK_UNCONNECTED		(1<<0)
 #define PEND_WR_TIME		(1<<2)
 #define PEND_WR_DATE		(1<<3)
 #define LOST_WR_TIME		(1<<4)
 #define LOST_WR_DATE		(1<<5)
 #define RTC_INT_MASK		(1<<31)
 #define STATUS_BUSY		(PEND_WR_TIME | PEND_WR_DATE)
 #define STATUS_FAIL		(LOST_WR_TIME | LOST_WR_DATE)

 struct spear_rtc_config {
 	struct rtc_device *rtc;
 	struct clk *clk;
 	spinlock_t lock;
 	void __iomem *ioaddr;
 	unsigned int irq_wake;
 };

 static inline void spear_rtc_clear_interrupt(struct spear_rtc_config *config)
 {
 	unsigned int val;
 	unsigned long flags;

 	spin_lock_irqsave(&config->lock, flags);
 	val = readl(config->ioaddr + STATUS_REG);
 	val |= RTC_INT_MASK;
 	writel(val, config->ioaddr + STATUS_REG);
 	spin_unlock_irqrestore(&config->lock, flags);
 }

 static inline void spear_rtc_enable_interrupt(struct spear_rtc_config *config)
 {
 	unsigned int val;

 	val = readl(config->ioaddr + CTRL_REG);
 	if (!(val & INT_ENABLE)) {
 		spear_rtc_clear_interrupt(config);
 		val |= INT_ENABLE;
 		writel(val, config->ioaddr + CTRL_REG);
 	}
 }

 static inline void spear_rtc_disable_interrupt(struct spear_rtc_config *config)
 {
 	unsigned int val;

 	val = readl(config->ioaddr + CTRL_REG);
 	if (val & INT_ENABLE) {
 		val &= ~INT_ENABLE;
 		writel(val, config->ioaddr + CTRL_REG);
 	}
 }

 static inline int is_write_complete(struct spear_rtc_config *config)
 {
 	int ret = 0;
 	unsigned long flags;

 	spin_lock_irqsave(&config->lock, flags);
 	if ((readl(config->ioaddr + STATUS_REG)) & STATUS_FAIL)
 		ret = -EIO;
 	spin_unlock_irqrestore(&config->lock, flags);

 	return ret;
 }

 static void rtc_wait_not_busy(struct spear_rtc_config *config)
 {
 	int status, count = 0;
 	unsigned long flags;

 	/* Assuming BUSY may stay active for 80 msec) */
 	for (count = 0; count < 80; count++) {
 		spin_lock_irqsave(&config->lock, flags);
 		status = readl(config->ioaddr + STATUS_REG);
 		spin_unlock_irqrestore(&config->lock, flags);
 		if ((status & STATUS_BUSY) == 0)
 			break;
 		/* check status busy, after each msec */
 		msleep(1);
 	}
 }

 static irqreturn_t spear_rtc_irq(int irq, void *dev_id)
 {
 	struct spear_rtc_config *config = dev_id;
 	unsigned long events = 0;
 	unsigned int irq_data;

 	spin_lock(&config->lock);
 	irq_data = readl(config->ioaddr + STATUS_REG);
 	spin_unlock(&config->lock);

 	if ((irq_data & RTC_INT_MASK)) {
 		spear_rtc_clear_interrupt(config);
 		events = RTC_IRQF | RTC_AF;
 		rtc_update_irq(config->rtc, 1, events);
 		return IRQ_HANDLED;
 	} else
 		return IRQ_NONE;

 }

 static void tm2bcd(struct rtc_time *tm)
 {
 	tm->tm_sec = bin2bcd(tm->tm_sec);
 	tm->tm_min = bin2bcd(tm->tm_min);
 	tm->tm_hour = bin2bcd(tm->tm_hour);
 	tm->tm_mday = bin2bcd(tm->tm_mday);
 	tm->tm_mon = bin2bcd(tm->tm_mon + 1);
 	tm->tm_year = bin2bcd(tm->tm_year);
 }

 static void bcd2tm(struct rtc_time *tm)
 {
 	tm->tm_sec = bcd2bin(tm->tm_sec);
 	tm->tm_min = bcd2bin(tm->tm_min);
 	tm->tm_hour = bcd2bin(tm->tm_hour);
 	tm->tm_mday = bcd2bin(tm->tm_mday);
 	tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
 	/* epoch == 1900 */
 	tm->tm_year = bcd2bin(tm->tm_year);
 }

 /*
  * spear_rtc_read_time - set the time
  * @dev: rtc device in use
  * @tm: holds date and time
  *
  * This function read time and date. On success it will return 0
  * otherwise -ve error is returned.
  */
 static int spear_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct spear_rtc_config *config = dev_get_drvdata(dev);
 	unsigned int time, date;

 	/* we don't report wday/yday/isdst ... */
 	rtc_wait_not_busy(config);

 	time = readl(config->ioaddr + TIME_REG);
 	date = readl(config->ioaddr + DATE_REG);
 	tm->tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
 	tm->tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
 	tm->tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
 	tm->tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
 	tm->tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
 	tm->tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

 	bcd2tm(tm);
 	return 0;
 }

 /*
  * spear_rtc_set_time - set the time
  * @dev: rtc device in use
  * @tm: holds date and time
  *
  * This function set time and date. On success it will return 0
  * otherwise -ve error is returned.
  */
 static int spear_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct spear_rtc_config *config = dev_get_drvdata(dev);
 	unsigned int time, date;

 	tm2bcd(tm);

 	rtc_wait_not_busy(config);
 	time = (tm->tm_sec << SECOND_SHIFT) | (tm->tm_min << MINUTE_SHIFT) |
 		(tm->tm_hour << HOUR_SHIFT);
 	date = (tm->tm_mday << MDAY_SHIFT) | (tm->tm_mon << MONTH_SHIFT) |
 		(tm->tm_year << YEAR_SHIFT);
 	writel(time, config->ioaddr + TIME_REG);
 	writel(date, config->ioaddr + DATE_REG);

 	return is_write_complete(config);
 }

 /*
  * spear_rtc_read_alarm - read the alarm time
  * @dev: rtc device in use
  * @alm: holds alarm date and time
  *
  * This function read alarm time and date. On success it will return 0
  * otherwise -ve error is returned.
  */
 static int spear_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
 	struct spear_rtc_config *config = dev_get_drvdata(dev);
 	unsigned int time, date;

 	rtc_wait_not_busy(config);

 	time = readl(config->ioaddr + ALARM_TIME_REG);
 	date = readl(config->ioaddr + ALARM_DATE_REG);
 	alm->time.tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
 	alm->time.tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
 	alm->time.tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
 	alm->time.tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
 	alm->time.tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
 	alm->time.tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

 	bcd2tm(&alm->time);
 	alm->enabled = readl(config->ioaddr + CTRL_REG) & INT_ENABLE;

 	return 0;
 }

 /*
  * spear_rtc_set_alarm - set the alarm time
  * @dev: rtc device in use
  * @alm: holds alarm date and time
  *
  * This function set alarm time and date. On success it will return 0
  * otherwise -ve error is returned.
  */
 static int spear_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
 	struct spear_rtc_config *config = dev_get_drvdata(dev);
 	unsigned int time, date;
 	int err;

 	tm2bcd(&alm->time);

 	rtc_wait_not_busy(config);

 	time = (alm->time.tm_sec << SECOND_SHIFT) | (alm->time.tm_min <<
 			MINUTE_SHIFT) |	(alm->time.tm_hour << HOUR_SHIFT);
 	date = (alm->time.tm_mday << MDAY_SHIFT) | (alm->time.tm_mon <<
 			MONTH_SHIFT) | (alm->time.tm_year << YEAR_SHIFT);

 	writel(time, config->ioaddr + ALARM_TIME_REG);
 	writel(date, config->ioaddr + ALARM_DATE_REG);
 	err = is_write_complete(config);
 	if (err < 0)
 		return err;

 	if (alm->enabled)
 		spear_rtc_enable_interrupt(config);
 	else
 		spear_rtc_disable_interrupt(config);

 	return 0;
 }

 static int spear_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct spear_rtc_config *config = dev_get_drvdata(dev);
 	int ret = 0;

 	spear_rtc_clear_interrupt(config);

 	switch (enabled) {
 	case 0:
 		/* alarm off */
 		spear_rtc_disable_interrupt(config);
 		break;
 	case 1:
 		/* alarm on */
 		spear_rtc_enable_interrupt(config);
 		break;
 	default:
 		ret = -EINVAL;
 		break;
 	}

 	return ret;
 }

 static const struct rtc_class_ops spear_rtc_ops = {
 	.read_time = spear_rtc_read_time,
 	.set_time = spear_rtc_set_time,
 	.read_alarm = spear_rtc_read_alarm,
 	.set_alarm = spear_rtc_set_alarm,
 	.alarm_irq_enable = spear_alarm_irq_enable,
 };

 static int spear_rtc_probe(struct platform_device *pdev)
 {
 	struct spear_rtc_config *config;
 	int status = 0;
 	int irq;

 	config = devm_kzalloc(&pdev->dev, sizeof(*config), GFP_KERNEL);
 	if (!config)
 		return -ENOMEM;

 	/* alarm irqs */
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
 		return irq;

 	status = devm_request_irq(&pdev->dev, irq, spear_rtc_irq, 0, pdev->name,
 			config);
 	if (status) {
 		dev_err(&pdev->dev, "Alarm interrupt IRQ%d already claimed\n",
 				irq);
 		return status;
 	}

 	config->ioaddr = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(config->ioaddr))
 		return PTR_ERR(config->ioaddr);

 	config->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(config->clk))
 		return PTR_ERR(config->clk);

 	status = clk_prepare_enable(config->clk);
 	if (status < 0)
 		return status;

 	spin_lock_init(&config->lock);
 	platform_set_drvdata(pdev, config);

 	config->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 					&spear_rtc_ops, THIS_MODULE);
 	if (IS_ERR(config->rtc)) {
 		dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
 				PTR_ERR(config->rtc));
 		status = PTR_ERR(config->rtc);
 		goto err_disable_clock;
 	}

 	config->rtc->uie_unsupported = 1;

 	if (!device_can_wakeup(&pdev->dev))
 		device_init_wakeup(&pdev->dev, 1);

 	return 0;

 err_disable_clock:
 	clk_disable_unprepare(config->clk);

 	return status;
 }

 static int spear_rtc_remove(struct platform_device *pdev)
 {
 	struct spear_rtc_config *config = platform_get_drvdata(pdev);

 	spear_rtc_disable_interrupt(config);
 	clk_disable_unprepare(config->clk);
 	device_init_wakeup(&pdev->dev, 0);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int spear_rtc_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct spear_rtc_config *config = platform_get_drvdata(pdev);
 	int irq;

 	irq = platform_get_irq(pdev, 0);
 	if (device_may_wakeup(&pdev->dev)) {
 		if (!enable_irq_wake(irq))
 			config->irq_wake = 1;
 	} else {
 		spear_rtc_disable_interrupt(config);
 		clk_disable(config->clk);
 	}

 	return 0;
 }

 static int spear_rtc_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct spear_rtc_config *config = platform_get_drvdata(pdev);
 	int irq;

 	irq = platform_get_irq(pdev, 0);

 	if (device_may_wakeup(&pdev->dev)) {
 		if (config->irq_wake) {
 			disable_irq_wake(irq);
 			config->irq_wake = 0;
 		}
 	} else {
 		clk_enable(config->clk);
 		spear_rtc_enable_interrupt(config);
 	}

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(spear_rtc_pm_ops, spear_rtc_suspend, spear_rtc_resume);

 static void spear_rtc_shutdown(struct platform_device *pdev)
 {
 	struct spear_rtc_config *config = platform_get_drvdata(pdev);

 	spear_rtc_disable_interrupt(config);
 	clk_disable(config->clk);
 }

 #ifdef CONFIG_OF
 static const struct of_device_id spear_rtc_id_table[] = {
 	{ .compatible = "st,spear600-rtc" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, spear_rtc_id_table);
 #endif

 static struct platform_driver spear_rtc_driver = {
 	.probe = spear_rtc_probe,
 	.remove = spear_rtc_remove,
 	.shutdown = spear_rtc_shutdown,
 	.driver = {
 		.name = "rtc-spear",
 		.pm = &spear_rtc_pm_ops,
 		.of_match_table = of_match_ptr(spear_rtc_id_table),
 	},
 };

 module_platform_driver(spear_rtc_driver);

 MODULE_ALIAS("platform:rtc-spear");
 MODULE_AUTHOR("Rajeev Kumar <rajeev-dlh.kumar@st.com>");
 MODULE_DESCRIPTION("ST SPEAr Realtime Clock Driver (RTC)");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* drivers/rtc/rtc-spear.c
	*
	* Copyright (C) 2010 ST Microelectronics
	* Rajeev Kumar<rajeev-dlh.kumar@st.com>
	*/

	#include <linux/bcd.h>
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/irq.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/rtc.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>

	/* RTC registers */
	#define TIME_REG 0x00
	#define DATE_REG 0x04
	#define ALARM_TIME_REG 0x08
	#define ALARM_DATE_REG 0x0C
	#define CTRL_REG 0x10
	#define STATUS_REG 0x14

	/* TIME_REG & ALARM_TIME_REG */
	#define SECONDS_UNITS (0xf<<0) /* seconds units position */
	#define SECONDS_TENS (0x7<<4) /* seconds tens position */
	#define MINUTES_UNITS (0xf<<8) /* minutes units position */
	#define MINUTES_TENS (0x7<<12) /* minutes tens position */
	#define HOURS_UNITS (0xf<<16) /* hours units position */
	#define HOURS_TENS (0x3<<20) /* hours tens position */

	/* DATE_REG & ALARM_DATE_REG */
	#define DAYS_UNITS (0xf<<0) /* days units position */
	#define DAYS_TENS (0x3<<4) /* days tens position */
	#define MONTHS_UNITS (0xf<<8) /* months units position */
	#define MONTHS_TENS (0x1<<12) /* months tens position */
	#define YEARS_UNITS (0xf<<16) /* years units position */
	#define YEARS_TENS (0xf<<20) /* years tens position */
	#define YEARS_HUNDREDS (0xf<<24) /* years hundereds position */
	#define YEARS_MILLENIUMS (0xf<<28) /* years millenium position */

	/* MASK SHIFT TIME_REG & ALARM_TIME_REG*/
	#define SECOND_SHIFT 0x00 /* seconds units */
	#define MINUTE_SHIFT 0x08 /* minutes units position */
	#define HOUR_SHIFT 0x10 /* hours units position */
	#define MDAY_SHIFT 0x00 /* Month day shift */
	#define MONTH_SHIFT 0x08 /* Month shift */
	#define YEAR_SHIFT 0x10 /* Year shift */

	#define SECOND_MASK 0x7F
	#define MIN_MASK 0x7F
	#define HOUR_MASK 0x3F
	#define DAY_MASK 0x3F
	#define MONTH_MASK 0x7F
	#define YEAR_MASK 0xFFFF

	/* date reg equal to time reg, for debug only */
	#define TIME_BYP (1<<9)
	#define INT_ENABLE (1<<31) /* interrupt enable */

	/* STATUS_REG */
	#define CLK_UNCONNECTED (1<<0)
	#define PEND_WR_TIME (1<<2)
	#define PEND_WR_DATE (1<<3)
	#define LOST_WR_TIME (1<<4)
	#define LOST_WR_DATE (1<<5)
	#define RTC_INT_MASK (1<<31)
	#define STATUS_BUSY (PEND_WR_TIME \| PEND_WR_DATE)
	#define STATUS_FAIL (LOST_WR_TIME \| LOST_WR_DATE)

	struct spear_rtc_config {
	struct rtc_device *rtc;
	struct clk *clk;
	spinlock_t lock;
	void __iomem *ioaddr;
	unsigned int irq_wake;
	};

	static inline void spear_rtc_clear_interrupt(struct spear_rtc_config *config)
	{
	unsigned int val;
	unsigned long flags;

	spin_lock_irqsave(&config->lock, flags);
	val = readl(config->ioaddr + STATUS_REG);
	val \|= RTC_INT_MASK;
	writel(val, config->ioaddr + STATUS_REG);
	spin_unlock_irqrestore(&config->lock, flags);
	}

	static inline void spear_rtc_enable_interrupt(struct spear_rtc_config *config)
	{
	unsigned int val;

	val = readl(config->ioaddr + CTRL_REG);
	if (!(val & INT_ENABLE)) {
	spear_rtc_clear_interrupt(config);
	val \|= INT_ENABLE;
	writel(val, config->ioaddr + CTRL_REG);
	}
	}

	static inline void spear_rtc_disable_interrupt(struct spear_rtc_config *config)
	{
	unsigned int val;

	val = readl(config->ioaddr + CTRL_REG);
	if (val & INT_ENABLE) {
	val &= ~INT_ENABLE;
	writel(val, config->ioaddr + CTRL_REG);
	}
	}

	static inline int is_write_complete(struct spear_rtc_config *config)
	{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&config->lock, flags);
	if ((readl(config->ioaddr + STATUS_REG)) & STATUS_FAIL)
	ret = -EIO;
	spin_unlock_irqrestore(&config->lock, flags);

	return ret;
	}

	static void rtc_wait_not_busy(struct spear_rtc_config *config)
	{
	int status, count = 0;
	unsigned long flags;

	/* Assuming BUSY may stay active for 80 msec) */
	for (count = 0; count < 80; count++) {
	spin_lock_irqsave(&config->lock, flags);
	status = readl(config->ioaddr + STATUS_REG);
	spin_unlock_irqrestore(&config->lock, flags);
	if ((status & STATUS_BUSY) == 0)
	break;
	/* check status busy, after each msec */
	msleep(1);
	}
	}

	static irqreturn_t spear_rtc_irq(int irq, void *dev_id)
	{
	struct spear_rtc_config *config = dev_id;
	unsigned long events = 0;
	unsigned int irq_data;

	spin_lock(&config->lock);
	irq_data = readl(config->ioaddr + STATUS_REG);
	spin_unlock(&config->lock);

	if ((irq_data & RTC_INT_MASK)) {
	spear_rtc_clear_interrupt(config);
	events = RTC_IRQF \| RTC_AF;
	rtc_update_irq(config->rtc, 1, events);
	return IRQ_HANDLED;
	} else
	return IRQ_NONE;

	}

	static void tm2bcd(struct rtc_time *tm)
	{
	tm->tm_sec = bin2bcd(tm->tm_sec);
	tm->tm_min = bin2bcd(tm->tm_min);
	tm->tm_hour = bin2bcd(tm->tm_hour);
	tm->tm_mday = bin2bcd(tm->tm_mday);
	tm->tm_mon = bin2bcd(tm->tm_mon + 1);
	tm->tm_year = bin2bcd(tm->tm_year);
	}

	static void bcd2tm(struct rtc_time *tm)
	{
	tm->tm_sec = bcd2bin(tm->tm_sec);
	tm->tm_min = bcd2bin(tm->tm_min);
	tm->tm_hour = bcd2bin(tm->tm_hour);
	tm->tm_mday = bcd2bin(tm->tm_mday);
	tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
	/* epoch == 1900 */
	tm->tm_year = bcd2bin(tm->tm_year);
	}

	/*
	* spear_rtc_read_time - set the time
	* @dev: rtc device in use
	* @tm: holds date and time
	*
	* This function read time and date. On success it will return 0
	* otherwise -ve error is returned.
	*/
	static int spear_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct spear_rtc_config *config = dev_get_drvdata(dev);
	unsigned int time, date;

	/* we don't report wday/yday/isdst ... */
	rtc_wait_not_busy(config);

	time = readl(config->ioaddr + TIME_REG);
	date = readl(config->ioaddr + DATE_REG);
	tm->tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
	tm->tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
	tm->tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
	tm->tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
	tm->tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
	tm->tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

	bcd2tm(tm);
	return 0;
	}

	/*
	* spear_rtc_set_time - set the time
	* @dev: rtc device in use
	* @tm: holds date and time
	*
	* This function set time and date. On success it will return 0
	* otherwise -ve error is returned.
	*/
	static int spear_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct spear_rtc_config *config = dev_get_drvdata(dev);
	unsigned int time, date;

	tm2bcd(tm);

	rtc_wait_not_busy(config);
	time = (tm->tm_sec << SECOND_SHIFT) \| (tm->tm_min << MINUTE_SHIFT) \|
	(tm->tm_hour << HOUR_SHIFT);
	date = (tm->tm_mday << MDAY_SHIFT) \| (tm->tm_mon << MONTH_SHIFT) \|
	(tm->tm_year << YEAR_SHIFT);
	writel(time, config->ioaddr + TIME_REG);
	writel(date, config->ioaddr + DATE_REG);

	return is_write_complete(config);
	}

	/*
	* spear_rtc_read_alarm - read the alarm time
	* @dev: rtc device in use
	* @alm: holds alarm date and time
	*
	* This function read alarm time and date. On success it will return 0
	* otherwise -ve error is returned.
	*/
	static int spear_rtc_read_alarm(struct device dev, struct rtc_wkalrm alm)
	{
	struct spear_rtc_config *config = dev_get_drvdata(dev);
	unsigned int time, date;

	rtc_wait_not_busy(config);

	time = readl(config->ioaddr + ALARM_TIME_REG);
	date = readl(config->ioaddr + ALARM_DATE_REG);
	alm->time.tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
	alm->time.tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
	alm->time.tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
	alm->time.tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
	alm->time.tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
	alm->time.tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

	bcd2tm(&alm->time);
	alm->enabled = readl(config->ioaddr + CTRL_REG) & INT_ENABLE;

	return 0;
	}

	/*
	* spear_rtc_set_alarm - set the alarm time
	* @dev: rtc device in use
	* @alm: holds alarm date and time
	*
	* This function set alarm time and date. On success it will return 0
	* otherwise -ve error is returned.
	*/
	static int spear_rtc_set_alarm(struct device dev, struct rtc_wkalrm alm)
	{
	struct spear_rtc_config *config = dev_get_drvdata(dev);
	unsigned int time, date;
	int err;

	tm2bcd(&alm->time);

	rtc_wait_not_busy(config);

	time = (alm->time.tm_sec << SECOND_SHIFT) \| (alm->time.tm_min <<
	MINUTE_SHIFT) \| (alm->time.tm_hour << HOUR_SHIFT);
	date = (alm->time.tm_mday << MDAY_SHIFT) \| (alm->time.tm_mon <<
	MONTH_SHIFT) \| (alm->time.tm_year << YEAR_SHIFT);

	writel(time, config->ioaddr + ALARM_TIME_REG);
	writel(date, config->ioaddr + ALARM_DATE_REG);
	err = is_write_complete(config);
	if (err < 0)
	return err;

	if (alm->enabled)
	spear_rtc_enable_interrupt(config);
	else
	spear_rtc_disable_interrupt(config);

	return 0;
	}

	static int spear_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct spear_rtc_config *config = dev_get_drvdata(dev);
	int ret = 0;

	spear_rtc_clear_interrupt(config);

	switch (enabled) {
	case 0:
	/* alarm off */
	spear_rtc_disable_interrupt(config);
	break;
	case 1:
	/* alarm on */
	spear_rtc_enable_interrupt(config);
	break;
	default:
	ret = -EINVAL;
	break;
	}

	return ret;
	}

	static const struct rtc_class_ops spear_rtc_ops = {
	.read_time = spear_rtc_read_time,
	.set_time = spear_rtc_set_time,
	.read_alarm = spear_rtc_read_alarm,
	.set_alarm = spear_rtc_set_alarm,
	.alarm_irq_enable = spear_alarm_irq_enable,
	};

	static int spear_rtc_probe(struct platform_device *pdev)
	{
	struct spear_rtc_config *config;
	int status = 0;
	int irq;

	config = devm_kzalloc(&pdev->dev, sizeof(*config), GFP_KERNEL);
	if (!config)
	return -ENOMEM;

	/* alarm irqs */
	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
	return irq;

	status = devm_request_irq(&pdev->dev, irq, spear_rtc_irq, 0, pdev->name,
	config);
	if (status) {
	dev_err(&pdev->dev, "Alarm interrupt IRQ%d already claimed\n",
	irq);
	return status;
	}

	config->ioaddr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(config->ioaddr))
	return PTR_ERR(config->ioaddr);

	config->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(config->clk))
	return PTR_ERR(config->clk);

	status = clk_prepare_enable(config->clk);
	if (status < 0)
	return status;

	spin_lock_init(&config->lock);
	platform_set_drvdata(pdev, config);

	config->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
	&spear_rtc_ops, THIS_MODULE);
	if (IS_ERR(config->rtc)) {
	dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
	PTR_ERR(config->rtc));
	status = PTR_ERR(config->rtc);
	goto err_disable_clock;
	}

	config->rtc->uie_unsupported = 1;

	if (!device_can_wakeup(&pdev->dev))
	device_init_wakeup(&pdev->dev, 1);

	return 0;

	err_disable_clock:
	clk_disable_unprepare(config->clk);

	return status;
	}

	static int spear_rtc_remove(struct platform_device *pdev)
	{
	struct spear_rtc_config *config = platform_get_drvdata(pdev);

	spear_rtc_disable_interrupt(config);
	clk_disable_unprepare(config->clk);
	device_init_wakeup(&pdev->dev, 0);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int spear_rtc_suspend(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct spear_rtc_config *config = platform_get_drvdata(pdev);
	int irq;

	irq = platform_get_irq(pdev, 0);
	if (device_may_wakeup(&pdev->dev)) {
	if (!enable_irq_wake(irq))
	config->irq_wake = 1;
	} else {
	spear_rtc_disable_interrupt(config);
	clk_disable(config->clk);
	}

	return 0;
	}

	static int spear_rtc_resume(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct spear_rtc_config *config = platform_get_drvdata(pdev);
	int irq;

	irq = platform_get_irq(pdev, 0);

	if (device_may_wakeup(&pdev->dev)) {
	if (config->irq_wake) {
	disable_irq_wake(irq);
	config->irq_wake = 0;
	}
	} else {
	clk_enable(config->clk);
	spear_rtc_enable_interrupt(config);
	}

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(spear_rtc_pm_ops, spear_rtc_suspend, spear_rtc_resume);

	static void spear_rtc_shutdown(struct platform_device *pdev)
	{
	struct spear_rtc_config *config = platform_get_drvdata(pdev);

	spear_rtc_disable_interrupt(config);
	clk_disable(config->clk);
	}

	#ifdef CONFIG_OF
	static const struct of_device_id spear_rtc_id_table[] = {
	{ .compatible = "st,spear600-rtc" },
	{}
	};
	MODULE_DEVICE_TABLE(of, spear_rtc_id_table);
	#endif

	static struct platform_driver spear_rtc_driver = {
	.probe = spear_rtc_probe,
	.remove = spear_rtc_remove,
	.shutdown = spear_rtc_shutdown,
	.driver = {
	.name = "rtc-spear",
	.pm = &spear_rtc_pm_ops,
	.of_match_table = of_match_ptr(spear_rtc_id_table),
	},
	};

	module_platform_driver(spear_rtc_driver);

	MODULE_ALIAS("platform:rtc-spear");
	MODULE_AUTHOR("Rajeev Kumar <rajeev-dlh.kumar@st.com>");
	MODULE_DESCRIPTION("ST SPEAr Realtime Clock Driver (RTC)");
	MODULE_LICENSE("GPL");