drivers/rtc/rtc-ab8500.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) ST-Ericsson SA 2010
  *
  * License terms: GNU General Public License (GPL) version 2
  * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
  *
  * RTC clock driver for the RTC part of the AB8500 Power management chip.
  * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
  * Linus Walleij <linus.walleij@stericsson.com>
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
 #include <linux/mfd/abx500.h>
 #include <linux/mfd/abx500/ab8500.h>
 #include <linux/delay.h>
 #include <linux/of.h>

 #define AB8500_RTC_SOFF_STAT_REG	0x00
 #define AB8500_RTC_CC_CONF_REG		0x01
 #define AB8500_RTC_READ_REQ_REG		0x02
 #define AB8500_RTC_WATCH_TSECMID_REG	0x03
 #define AB8500_RTC_WATCH_TSECHI_REG	0x04
 #define AB8500_RTC_WATCH_TMIN_LOW_REG	0x05
 #define AB8500_RTC_WATCH_TMIN_MID_REG	0x06
 #define AB8500_RTC_WATCH_TMIN_HI_REG	0x07
 #define AB8500_RTC_ALRM_MIN_LOW_REG	0x08
 #define AB8500_RTC_ALRM_MIN_MID_REG	0x09
 #define AB8500_RTC_ALRM_MIN_HI_REG	0x0A
 #define AB8500_RTC_STAT_REG		0x0B
 #define AB8500_RTC_BKUP_CHG_REG		0x0C
 #define AB8500_RTC_FORCE_BKUP_REG	0x0D
 #define AB8500_RTC_CALIB_REG		0x0E
 #define AB8500_RTC_SWITCH_STAT_REG	0x0F
 #define AB8540_RTC_ALRM_SEC		0x22
 #define AB8540_RTC_ALRM_MIN_LOW_REG	0x23
 #define AB8540_RTC_ALRM_MIN_MID_REG	0x24
 #define AB8540_RTC_ALRM_MIN_HI_REG	0x25

 /* RtcReadRequest bits */
 #define RTC_READ_REQUEST		0x01
 #define RTC_WRITE_REQUEST		0x02

 /* RtcCtrl bits */
 #define RTC_ALARM_ENA			0x04
 #define RTC_STATUS_DATA			0x01

 #define COUNTS_PER_SEC			(0xF000 / 60)
 #define AB8500_RTC_EPOCH		2000

 static const u8 ab8500_rtc_time_regs[] = {
 	AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
 	AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
 	AB8500_RTC_WATCH_TSECMID_REG
 };

 static const u8 ab8500_rtc_alarm_regs[] = {
 	AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
 	AB8500_RTC_ALRM_MIN_LOW_REG
 };

 static const u8 ab8540_rtc_alarm_regs[] = {
 	AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
 	AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
 };

 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
 static unsigned long get_elapsed_seconds(int year)
 {
 	unsigned long secs;
 	struct rtc_time tm = {
 		.tm_year = year - 1900,
 		.tm_mday = 1,
 	};

 	/*
 	 * This function calculates secs from 1970 and not from
 	 * 1900, even if we supply the offset from year 1900.
 	 */
 	rtc_tm_to_time(&tm, &secs);
 	return secs;
 }

 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned long timeout = jiffies + HZ;
 	int retval, i;
 	unsigned long mins, secs;
 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 	u8 value;

 	/* Request a data read */
 	retval = abx500_set_register_interruptible(dev,
 		AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
 	if (retval < 0)
 		return retval;

 	/* Wait for some cycles after enabling the rtc read in ab8500 */
 	while (time_before(jiffies, timeout)) {
 		retval = abx500_get_register_interruptible(dev,
 			AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
 		if (retval < 0)
 			return retval;

 		if (!(value & RTC_READ_REQUEST))
 			break;

 		usleep_range(1000, 5000);
 	}

 	/* Read the Watchtime registers */
 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 		retval = abx500_get_register_interruptible(dev,
 			AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 		if (retval < 0)
 			return retval;
 		buf[i] = value;
 	}

 	mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];

 	secs =	(buf[3] << 8) | buf[4];
 	secs =	secs / COUNTS_PER_SEC;
 	secs =	secs + (mins * 60);

 	/* Add back the initially subtracted number of seconds */
 	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

 	rtc_time_to_tm(secs, tm);
 	return rtc_valid_tm(tm);
 }

 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	int retval, i;
 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 	unsigned long no_secs, no_mins, secs = 0;

 	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 		dev_dbg(dev, "year should be equal to or greater than %d\n",
 				AB8500_RTC_EPOCH);
 		return -EINVAL;
 	}

 	/* Get the number of seconds since 1970 */
 	rtc_tm_to_time(tm, &secs);

 	/*
 	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 	 * we only have a small counter in the RTC.
 	 */
 	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

 	no_mins = secs / 60;

 	no_secs = secs % 60;
 	/* Make the seconds count as per the RTC resolution */
 	no_secs = no_secs * COUNTS_PER_SEC;

 	buf[4] = no_secs & 0xFF;
 	buf[3] = (no_secs >> 8) & 0xFF;

 	buf[2] = no_mins & 0xFF;
 	buf[1] = (no_mins >> 8) & 0xFF;
 	buf[0] = (no_mins >> 16) & 0xFF;

 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 			ab8500_rtc_time_regs[i], buf[i]);
 		if (retval < 0)
 			return retval;
 	}

 	/* Request a data write */
 	return abx500_set_register_interruptible(dev, AB8500_RTC,
 		AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 }

 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	int retval, i;
 	u8 rtc_ctrl, value;
 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 	unsigned long secs, mins;

 	/* Check if the alarm is enabled or not */
 	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 		AB8500_RTC_STAT_REG, &rtc_ctrl);
 	if (retval < 0)
 		return retval;

 	if (rtc_ctrl & RTC_ALARM_ENA)
 		alarm->enabled = 1;
 	else
 		alarm->enabled = 0;

 	alarm->pending = 0;

 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 		retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 			ab8500_rtc_alarm_regs[i], &value);
 		if (retval < 0)
 			return retval;
 		buf[i] = value;
 	}

 	mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 	secs = mins * 60;

 	/* Add back the initially subtracted number of seconds */
 	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

 	rtc_time_to_tm(secs, &alarm->time);

 	return rtc_valid_tm(&alarm->time);
 }

 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 {
 	return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 		AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 		enabled ? RTC_ALARM_ENA : 0);
 }

 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	int retval, i;
 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 	unsigned long mins, secs = 0, cursec = 0;
 	struct rtc_time curtm;

 	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 		dev_dbg(dev, "year should be equal to or greater than %d\n",
 				AB8500_RTC_EPOCH);
 		return -EINVAL;
 	}

 	/* Get the number of seconds since 1970 */
 	rtc_tm_to_time(&alarm->time, &secs);

 	/*
 	 * Check whether alarm is set less than 1min.
 	 * Since our RTC doesn't support alarm resolution less than 1min,
 	 * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 	 */
 	ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 	rtc_tm_to_time(&curtm, &cursec);
 	if ((secs - cursec) < 59) {
 		dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 		return -EINVAL;
 	}

 	/*
 	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 	 * we only have a small counter in the RTC.
 	 */
 	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

 	mins = secs / 60;

 	buf[2] = mins & 0xFF;
 	buf[1] = (mins >> 8) & 0xFF;
 	buf[0] = (mins >> 16) & 0xFF;

 	/* Set the alarm time */
 	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 			ab8500_rtc_alarm_regs[i], buf[i]);
 		if (retval < 0)
 			return retval;
 	}

 	return ab8500_rtc_irq_enable(dev, alarm->enabled);
 }

 static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	int retval, i;
 	unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
 	unsigned long mins, secs = 0;

 	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 		dev_dbg(dev, "year should be equal to or greater than %d\n",
 				AB8500_RTC_EPOCH);
 		return -EINVAL;
 	}

 	/* Get the number of seconds since 1970 */
 	rtc_tm_to_time(&alarm->time, &secs);

 	/*
 	 * Convert it to the number of seconds since 01-01-2000 00:00:00
 	 */
 	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 	mins = secs / 60;

 	buf[3] = secs % 60;
 	buf[2] = mins & 0xFF;
 	buf[1] = (mins >> 8) & 0xFF;
 	buf[0] = (mins >> 16) & 0xFF;

 	/* Set the alarm time */
 	for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
 		retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 			ab8540_rtc_alarm_regs[i], buf[i]);
 		if (retval < 0)
 			return retval;
 	}

 	return ab8500_rtc_irq_enable(dev, alarm->enabled);
 }

 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 {
 	int retval;
 	u8  rtccal = 0;

 	/*
 	 * Check that the calibration value (which is in units of 0.5
 	 * parts-per-million) is in the AB8500's range for RtcCalibration
 	 * register. -128 (0x80) is not permitted because the AB8500 uses
 	 * a sign-bit rather than two's complement, so 0x80 is just another
 	 * representation of zero.
 	 */
 	if ((calibration < -127) || (calibration > 127)) {
 		dev_err(dev, "RtcCalibration value outside permitted range\n");
 		return -EINVAL;
 	}

 	/*
 	 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 	 * so need to convert to this sort of representation before writing
 	 * into RtcCalibration register...
 	 */
 	if (calibration >= 0)
 		rtccal = 0x7F & calibration;
 	else
 		rtccal = ~(calibration - 1) | 0x80;

 	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 			AB8500_RTC_CALIB_REG, rtccal);

 	return retval;
 }

 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 {
 	int retval;
 	u8  rtccal = 0;

 	retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 			AB8500_RTC_CALIB_REG, &rtccal);
 	if (retval >= 0) {
 		/*
 		 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 		 * so need to convert value from RtcCalibration register into
 		 * a two's complement signed value...
 		 */
 		if (rtccal & 0x80)
 			*calibration = 0 - (rtccal & 0x7F);
 		else
 			*calibration = 0x7F & rtccal;
 	}

 	return retval;
 }

 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
 {
 	int retval;
 	int calibration = 0;

 	if (sscanf(buf, " %i ", &calibration) != 1) {
 		dev_err(dev, "Failed to store RTC calibration attribute\n");
 		return -EINVAL;
 	}

 	retval = ab8500_rtc_set_calibration(dev, calibration);

 	return retval ? retval : count;
 }

 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	int  retval = 0;
 	int  calibration = 0;

 	retval = ab8500_rtc_get_calibration(dev, &calibration);
 	if (retval < 0) {
 		dev_err(dev, "Failed to read RTC calibration attribute\n");
 		sprintf(buf, "0\n");
 		return retval;
 	}

 	return sprintf(buf, "%d\n", calibration);
 }

 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 		   ab8500_sysfs_show_rtc_calibration,
 		   ab8500_sysfs_store_rtc_calibration);

 static int ab8500_sysfs_rtc_register(struct device *dev)
 {
 	return device_create_file(dev, &dev_attr_rtc_calibration);
 }

 static void ab8500_sysfs_rtc_unregister(struct device *dev)
 {
 	device_remove_file(dev, &dev_attr_rtc_calibration);
 }

 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 {
 	struct rtc_device *rtc = data;
 	unsigned long events = RTC_IRQF | RTC_AF;

 	dev_dbg(&rtc->dev, "%s\n", __func__);
 	rtc_update_irq(rtc, 1, events);

 	return IRQ_HANDLED;
 }

 static const struct rtc_class_ops ab8500_rtc_ops = {
 	.read_time		= ab8500_rtc_read_time,
 	.set_time		= ab8500_rtc_set_time,
 	.read_alarm		= ab8500_rtc_read_alarm,
 	.set_alarm		= ab8500_rtc_set_alarm,
 	.alarm_irq_enable	= ab8500_rtc_irq_enable,
 };

 static const struct rtc_class_ops ab8540_rtc_ops = {
 	.read_time		= ab8500_rtc_read_time,
 	.set_time		= ab8500_rtc_set_time,
 	.read_alarm		= ab8500_rtc_read_alarm,
 	.set_alarm		= ab8540_rtc_set_alarm,
 	.alarm_irq_enable	= ab8500_rtc_irq_enable,
 };

 static struct platform_device_id ab85xx_rtc_ids[] = {
 	{ "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 	{ "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
 };

 static int ab8500_rtc_probe(struct platform_device *pdev)
 {
 	const struct platform_device_id *platid = platform_get_device_id(pdev);
 	int err;
 	struct rtc_device *rtc;
 	u8 rtc_ctrl;
 	int irq;

 	irq = platform_get_irq_byname(pdev, "ALARM");
 	if (irq < 0)
 		return irq;

 	/* For RTC supply test */
 	err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 		AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 	if (err < 0)
 		return err;

 	/* Wait for reset by the PorRtc */
 	usleep_range(1000, 5000);

 	err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 		AB8500_RTC_STAT_REG, &rtc_ctrl);
 	if (err < 0)
 		return err;

 	/* Check if the RTC Supply fails */
 	if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 		dev_err(&pdev->dev, "RTC supply failure\n");
 		return -ENODEV;
 	}

 	device_init_wakeup(&pdev->dev, true);

 	rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
 				(struct rtc_class_ops *)platid->driver_data,
 				THIS_MODULE);
 	if (IS_ERR(rtc)) {
 		dev_err(&pdev->dev, "Registration failed\n");
 		err = PTR_ERR(rtc);
 		return err;
 	}

 	err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 			rtc_alarm_handler, IRQF_NO_SUSPEND | IRQF_ONESHOT,
 			"ab8500-rtc", rtc);
 	if (err < 0)
 		return err;

 	platform_set_drvdata(pdev, rtc);

 	err = ab8500_sysfs_rtc_register(&pdev->dev);
 	if (err) {
 		dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 		return err;
 	}

 	return 0;
 }

 static int ab8500_rtc_remove(struct platform_device *pdev)
 {
 	ab8500_sysfs_rtc_unregister(&pdev->dev);

 	return 0;
 }

 static struct platform_driver ab8500_rtc_driver = {
 	.driver = {
 		.name = "ab8500-rtc",
 	},
 	.probe	= ab8500_rtc_probe,
 	.remove = ab8500_rtc_remove,
 	.id_table = ab85xx_rtc_ids,
 };

 module_platform_driver(ab8500_rtc_driver);

 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 MODULE_DESCRIPTION("AB8500 RTC Driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Copyright (C) ST-Ericsson SA 2010
	*
	* License terms: GNU General Public License (GPL) version 2
	* Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
	*
	* RTC clock driver for the RTC part of the AB8500 Power management chip.
	* Based on RTC clock driver for the AB3100 Analog Baseband Chip by
	* Linus Walleij <linus.walleij@stericsson.com>
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/platform_device.h>
	#include <linux/rtc.h>
	#include <linux/mfd/abx500.h>
	#include <linux/mfd/abx500/ab8500.h>
	#include <linux/delay.h>
	#include <linux/of.h>

	#define AB8500_RTC_SOFF_STAT_REG 0x00
	#define AB8500_RTC_CC_CONF_REG 0x01
	#define AB8500_RTC_READ_REQ_REG 0x02
	#define AB8500_RTC_WATCH_TSECMID_REG 0x03
	#define AB8500_RTC_WATCH_TSECHI_REG 0x04
	#define AB8500_RTC_WATCH_TMIN_LOW_REG 0x05
	#define AB8500_RTC_WATCH_TMIN_MID_REG 0x06
	#define AB8500_RTC_WATCH_TMIN_HI_REG 0x07
	#define AB8500_RTC_ALRM_MIN_LOW_REG 0x08
	#define AB8500_RTC_ALRM_MIN_MID_REG 0x09
	#define AB8500_RTC_ALRM_MIN_HI_REG 0x0A
	#define AB8500_RTC_STAT_REG 0x0B
	#define AB8500_RTC_BKUP_CHG_REG 0x0C
	#define AB8500_RTC_FORCE_BKUP_REG 0x0D
	#define AB8500_RTC_CALIB_REG 0x0E
	#define AB8500_RTC_SWITCH_STAT_REG 0x0F
	#define AB8540_RTC_ALRM_SEC 0x22
	#define AB8540_RTC_ALRM_MIN_LOW_REG 0x23
	#define AB8540_RTC_ALRM_MIN_MID_REG 0x24
	#define AB8540_RTC_ALRM_MIN_HI_REG 0x25

	/* RtcReadRequest bits */
	#define RTC_READ_REQUEST 0x01
	#define RTC_WRITE_REQUEST 0x02

	/* RtcCtrl bits */
	#define RTC_ALARM_ENA 0x04
	#define RTC_STATUS_DATA 0x01

	#define COUNTS_PER_SEC (0xF000 / 60)
	#define AB8500_RTC_EPOCH 2000

	static const u8 ab8500_rtc_time_regs[] = {
	AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
	AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
	AB8500_RTC_WATCH_TSECMID_REG
	};

	static const u8 ab8500_rtc_alarm_regs[] = {
	AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
	AB8500_RTC_ALRM_MIN_LOW_REG
	};

	static const u8 ab8540_rtc_alarm_regs[] = {
	AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
	AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
	};

	/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
	static unsigned long get_elapsed_seconds(int year)
	{
	unsigned long secs;
	struct rtc_time tm = {
	.tm_year = year - 1900,
	.tm_mday = 1,
	};

	/*
	* This function calculates secs from 1970 and not from
	* 1900, even if we supply the offset from year 1900.
	*/
	rtc_tm_to_time(&tm, &secs);
	return secs;
	}

	static int ab8500_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	unsigned long timeout = jiffies + HZ;
	int retval, i;
	unsigned long mins, secs;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
	u8 value;

	/* Request a data read */
	retval = abx500_set_register_interruptible(dev,
	AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
	if (retval < 0)
	return retval;

	/* Wait for some cycles after enabling the rtc read in ab8500 */
	while (time_before(jiffies, timeout)) {
	retval = abx500_get_register_interruptible(dev,
	AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
	if (retval < 0)
	return retval;

	if (!(value & RTC_READ_REQUEST))
	break;

	usleep_range(1000, 5000);
	}

	/* Read the Watchtime registers */
	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
	retval = abx500_get_register_interruptible(dev,
	AB8500_RTC, ab8500_rtc_time_regs[i], &value);
	if (retval < 0)
	return retval;
	buf[i] = value;
	}

	mins = (buf[0] << 16) \| (buf[1] << 8) \| buf[2];

	secs = (buf[3] << 8) \| buf[4];
	secs = secs / COUNTS_PER_SEC;
	secs = secs + (mins * 60);

	/* Add back the initially subtracted number of seconds */
	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

	rtc_time_to_tm(secs, tm);
	return rtc_valid_tm(tm);
	}

	static int ab8500_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
	unsigned long no_secs, no_mins, secs = 0;

	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
	dev_dbg(dev, "year should be equal to or greater than %d\n",
	AB8500_RTC_EPOCH);
	return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(tm, &secs);

	/*
	* Convert it to the number of seconds since 01-01-2000 00:00:00, since
	* we only have a small counter in the RTC.
	*/
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

	no_mins = secs / 60;

	no_secs = secs % 60;
	/* Make the seconds count as per the RTC resolution */
	no_secs = no_secs * COUNTS_PER_SEC;

	buf[4] = no_secs & 0xFF;
	buf[3] = (no_secs >> 8) & 0xFF;

	buf[2] = no_mins & 0xFF;
	buf[1] = (no_mins >> 8) & 0xFF;
	buf[0] = (no_mins >> 16) & 0xFF;

	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
	ab8500_rtc_time_regs[i], buf[i]);
	if (retval < 0)
	return retval;
	}

	/* Request a data write */
	return abx500_set_register_interruptible(dev, AB8500_RTC,
	AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
	}

	static int ab8500_rtc_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	int retval, i;
	u8 rtc_ctrl, value;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
	unsigned long secs, mins;

	/* Check if the alarm is enabled or not */
	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
	AB8500_RTC_STAT_REG, &rtc_ctrl);
	if (retval < 0)
	return retval;

	if (rtc_ctrl & RTC_ALARM_ENA)
	alarm->enabled = 1;
	else
	alarm->enabled = 0;

	alarm->pending = 0;

	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
	ab8500_rtc_alarm_regs[i], &value);
	if (retval < 0)
	return retval;
	buf[i] = value;
	}

	mins = (buf[0] << 16) \| (buf[1] << 8) \| (buf[2]);
	secs = mins * 60;

	/* Add back the initially subtracted number of seconds */
	secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

	rtc_time_to_tm(secs, &alarm->time);

	return rtc_valid_tm(&alarm->time);
	}

	static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
	{
	return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
	AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
	enabled ? RTC_ALARM_ENA : 0);
	}

	static int ab8500_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
	unsigned long mins, secs = 0, cursec = 0;
	struct rtc_time curtm;

	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
	dev_dbg(dev, "year should be equal to or greater than %d\n",
	AB8500_RTC_EPOCH);
	return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(&alarm->time, &secs);

	/*
	* Check whether alarm is set less than 1min.
	* Since our RTC doesn't support alarm resolution less than 1min,
	* return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
	*/
	ab8500_rtc_read_time(dev, &curtm); /* Read current time */
	rtc_tm_to_time(&curtm, &cursec);
	if ((secs - cursec) < 59) {
	dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
	return -EINVAL;
	}

	/*
	* Convert it to the number of seconds since 01-01-2000 00:00:00, since
	* we only have a small counter in the RTC.
	*/
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

	mins = secs / 60;

	buf[2] = mins & 0xFF;
	buf[1] = (mins >> 8) & 0xFF;
	buf[0] = (mins >> 16) & 0xFF;

	/* Set the alarm time */
	for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
	ab8500_rtc_alarm_regs[i], buf[i]);
	if (retval < 0)
	return retval;
	}

	return ab8500_rtc_irq_enable(dev, alarm->enabled);
	}

	static int ab8540_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	int retval, i;
	unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
	unsigned long mins, secs = 0;

	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
	dev_dbg(dev, "year should be equal to or greater than %d\n",
	AB8500_RTC_EPOCH);
	return -EINVAL;
	}

	/* Get the number of seconds since 1970 */
	rtc_tm_to_time(&alarm->time, &secs);

	/*
	* Convert it to the number of seconds since 01-01-2000 00:00:00
	*/
	secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
	mins = secs / 60;

	buf[3] = secs % 60;
	buf[2] = mins & 0xFF;
	buf[1] = (mins >> 8) & 0xFF;
	buf[0] = (mins >> 16) & 0xFF;

	/* Set the alarm time */
	for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
	ab8540_rtc_alarm_regs[i], buf[i]);
	if (retval < 0)
	return retval;
	}

	return ab8500_rtc_irq_enable(dev, alarm->enabled);
	}

	static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
	{
	int retval;
	u8 rtccal = 0;

	/*
	* Check that the calibration value (which is in units of 0.5
	* parts-per-million) is in the AB8500's range for RtcCalibration
	* register. -128 (0x80) is not permitted because the AB8500 uses
	* a sign-bit rather than two's complement, so 0x80 is just another
	* representation of zero.
	*/
	if ((calibration < -127) \|\| (calibration > 127)) {
	dev_err(dev, "RtcCalibration value outside permitted range\n");
	return -EINVAL;
	}

	/*
	* The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
	* so need to convert to this sort of representation before writing
	* into RtcCalibration register...
	*/
	if (calibration >= 0)
	rtccal = 0x7F & calibration;
	else
	rtccal = ~(calibration - 1) \| 0x80;

	retval = abx500_set_register_interruptible(dev, AB8500_RTC,
	AB8500_RTC_CALIB_REG, rtccal);

	return retval;
	}

	static int ab8500_rtc_get_calibration(struct device dev, int calibration)
	{
	int retval;
	u8 rtccal = 0;

	retval = abx500_get_register_interruptible(dev, AB8500_RTC,
	AB8500_RTC_CALIB_REG, &rtccal);
	if (retval >= 0) {
	/*
	* The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
	* so need to convert value from RtcCalibration register into
	* a two's complement signed value...
	*/
	if (rtccal & 0x80)
	*calibration = 0 - (rtccal & 0x7F);
	else
	*calibration = 0x7F & rtccal;
	}

	return retval;
	}

	static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	int retval;
	int calibration = 0;

	if (sscanf(buf, " %i ", &calibration) != 1) {
	dev_err(dev, "Failed to store RTC calibration attribute\n");
	return -EINVAL;
	}

	retval = ab8500_rtc_set_calibration(dev, calibration);

	return retval ? retval : count;
	}

	static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
	struct device_attribute attr, char buf)
	{
	int retval = 0;
	int calibration = 0;

	retval = ab8500_rtc_get_calibration(dev, &calibration);
	if (retval < 0) {
	dev_err(dev, "Failed to read RTC calibration attribute\n");
	sprintf(buf, "0\n");
	return retval;
	}

	return sprintf(buf, "%d\n", calibration);
	}

	static DEVICE_ATTR(rtc_calibration, S_IRUGO \| S_IWUSR,
	ab8500_sysfs_show_rtc_calibration,
	ab8500_sysfs_store_rtc_calibration);

	static int ab8500_sysfs_rtc_register(struct device *dev)
	{
	return device_create_file(dev, &dev_attr_rtc_calibration);
	}

	static void ab8500_sysfs_rtc_unregister(struct device *dev)
	{
	device_remove_file(dev, &dev_attr_rtc_calibration);
	}

	static irqreturn_t rtc_alarm_handler(int irq, void *data)
	{
	struct rtc_device *rtc = data;
	unsigned long events = RTC_IRQF \| RTC_AF;

	dev_dbg(&rtc->dev, "%s\n", __func__);
	rtc_update_irq(rtc, 1, events);

	return IRQ_HANDLED;
	}

	static const struct rtc_class_ops ab8500_rtc_ops = {
	.read_time = ab8500_rtc_read_time,
	.set_time = ab8500_rtc_set_time,
	.read_alarm = ab8500_rtc_read_alarm,
	.set_alarm = ab8500_rtc_set_alarm,
	.alarm_irq_enable = ab8500_rtc_irq_enable,
	};

	static const struct rtc_class_ops ab8540_rtc_ops = {
	.read_time = ab8500_rtc_read_time,
	.set_time = ab8500_rtc_set_time,
	.read_alarm = ab8500_rtc_read_alarm,
	.set_alarm = ab8540_rtc_set_alarm,
	.alarm_irq_enable = ab8500_rtc_irq_enable,
	};

	static struct platform_device_id ab85xx_rtc_ids[] = {
	{ "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
	{ "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
	};

	static int ab8500_rtc_probe(struct platform_device *pdev)
	{
	const struct platform_device_id *platid = platform_get_device_id(pdev);
	int err;
	struct rtc_device *rtc;
	u8 rtc_ctrl;
	int irq;

	irq = platform_get_irq_byname(pdev, "ALARM");
	if (irq < 0)
	return irq;

	/* For RTC supply test */
	err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
	AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
	if (err < 0)
	return err;

	/* Wait for reset by the PorRtc */
	usleep_range(1000, 5000);

	err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
	AB8500_RTC_STAT_REG, &rtc_ctrl);
	if (err < 0)
	return err;

	/* Check if the RTC Supply fails */
	if (!(rtc_ctrl & RTC_STATUS_DATA)) {
	dev_err(&pdev->dev, "RTC supply failure\n");
	return -ENODEV;
	}

	device_init_wakeup(&pdev->dev, true);

	rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
	(struct rtc_class_ops *)platid->driver_data,
	THIS_MODULE);
	if (IS_ERR(rtc)) {
	dev_err(&pdev->dev, "Registration failed\n");
	err = PTR_ERR(rtc);
	return err;
	}

	err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
	rtc_alarm_handler, IRQF_NO_SUSPEND \| IRQF_ONESHOT,
	"ab8500-rtc", rtc);
	if (err < 0)
	return err;

	platform_set_drvdata(pdev, rtc);

	err = ab8500_sysfs_rtc_register(&pdev->dev);
	if (err) {
	dev_err(&pdev->dev, "sysfs RTC failed to register\n");
	return err;
	}

	return 0;
	}

	static int ab8500_rtc_remove(struct platform_device *pdev)
	{
	ab8500_sysfs_rtc_unregister(&pdev->dev);

	return 0;
	}

	static struct platform_driver ab8500_rtc_driver = {
	.driver = {
	.name = "ab8500-rtc",
	},
	.probe = ab8500_rtc_probe,
	.remove = ab8500_rtc_remove,
	.id_table = ab85xx_rtc_ids,
	};

	module_platform_driver(ab8500_rtc_driver);

	MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
	MODULE_DESCRIPTION("AB8500 RTC Driver");
	MODULE_LICENSE("GPL v2");