drivers/rtc/rtc-pl031.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * drivers/rtc/rtc-pl031.c
  *
  * Real Time Clock interface for ARM AMBA PrimeCell 031 RTC
  *
  * Author: Deepak Saxena <dsaxena@plexity.net>
  *
  * Copyright 2006 (c) MontaVista Software, Inc.
  *
  * Author: Mian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
  * Copyright 2010 (c) ST-Ericsson AB
  */
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/amba/bus.h>
 #include <linux/io.h>
 #include <linux/bcd.h>
 #include <linux/delay.h>
 #include <linux/pm_wakeirq.h>
 #include <linux/slab.h>

 /*
  * Register definitions
  */
 #define	RTC_DR		0x00	/* Data read register */
 #define	RTC_MR		0x04	/* Match register */
 #define	RTC_LR		0x08	/* Data load register */
 #define	RTC_CR		0x0c	/* Control register */
 #define	RTC_IMSC	0x10	/* Interrupt mask and set register */
 #define	RTC_RIS		0x14	/* Raw interrupt status register */
 #define	RTC_MIS		0x18	/* Masked interrupt status register */
 #define	RTC_ICR		0x1c	/* Interrupt clear register */
 /* ST variants have additional timer functionality */
 #define RTC_TDR		0x20	/* Timer data read register */
 #define RTC_TLR		0x24	/* Timer data load register */
 #define RTC_TCR		0x28	/* Timer control register */
 #define RTC_YDR		0x30	/* Year data read register */
 #define RTC_YMR		0x34	/* Year match register */
 #define RTC_YLR		0x38	/* Year data load register */

 #define RTC_CR_EN	(1 << 0)	/* counter enable bit */
 #define RTC_CR_CWEN	(1 << 26)	/* Clockwatch enable bit */

 #define RTC_TCR_EN	(1 << 1) /* Periodic timer enable bit */

 /* Common bit definitions for Interrupt status and control registers */
 #define RTC_BIT_AI	(1 << 0) /* Alarm interrupt bit */
 #define RTC_BIT_PI	(1 << 1) /* Periodic interrupt bit. ST variants only. */

 /* Common bit definations for ST v2 for reading/writing time */
 #define RTC_SEC_SHIFT 0
 #define RTC_SEC_MASK (0x3F << RTC_SEC_SHIFT) /* Second [0-59] */
 #define RTC_MIN_SHIFT 6
 #define RTC_MIN_MASK (0x3F << RTC_MIN_SHIFT) /* Minute [0-59] */
 #define RTC_HOUR_SHIFT 12
 #define RTC_HOUR_MASK (0x1F << RTC_HOUR_SHIFT) /* Hour [0-23] */
 #define RTC_WDAY_SHIFT 17
 #define RTC_WDAY_MASK (0x7 << RTC_WDAY_SHIFT) /* Day of Week [1-7] 1=Sunday */
 #define RTC_MDAY_SHIFT 20
 #define RTC_MDAY_MASK (0x1F << RTC_MDAY_SHIFT) /* Day of Month [1-31] */
 #define RTC_MON_SHIFT 25
 #define RTC_MON_MASK (0xF << RTC_MON_SHIFT) /* Month [1-12] 1=January */

 #define RTC_TIMER_FREQ 32768

 /**
  * struct pl031_vendor_data - per-vendor variations
  * @ops: the vendor-specific operations used on this silicon version
  * @clockwatch: if this is an ST Microelectronics silicon version with a
  *	clockwatch function
  * @st_weekday: if this is an ST Microelectronics silicon version that need
  *	the weekday fix
  * @irqflags: special IRQ flags per variant
  */
 struct pl031_vendor_data {
 	struct rtc_class_ops ops;
 	bool clockwatch;
 	bool st_weekday;
 	unsigned long irqflags;
 	time64_t range_min;
 	timeu64_t range_max;
 };

 struct pl031_local {
 	struct pl031_vendor_data *vendor;
 	struct rtc_device *rtc;
 	void __iomem *base;
 };

 static int pl031_alarm_irq_enable(struct device *dev,
 	unsigned int enabled)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);
 	unsigned long imsc;

 	/* Clear any pending alarm interrupts. */
 	writel(RTC_BIT_AI, ldata->base + RTC_ICR);

 	imsc = readl(ldata->base + RTC_IMSC);

 	if (enabled == 1)
 		writel(imsc | RTC_BIT_AI, ldata->base + RTC_IMSC);
 	else
 		writel(imsc & ~RTC_BIT_AI, ldata->base + RTC_IMSC);

 	return 0;
 }

 /*
  * Convert Gregorian date to ST v2 RTC format.
  */
 static int pl031_stv2_tm_to_time(struct device *dev,
 				 struct rtc_time *tm, unsigned long *st_time,
 	unsigned long *bcd_year)
 {
 	int year = tm->tm_year + 1900;
 	int wday = tm->tm_wday;

 	/* wday masking is not working in hardware so wday must be valid */
 	if (wday < -1 || wday > 6) {
 		dev_err(dev, "invalid wday value %d\n", tm->tm_wday);
 		return -EINVAL;
 	} else if (wday == -1) {
 		/* wday is not provided, calculate it here */
 		struct rtc_time calc_tm;

 		rtc_time64_to_tm(rtc_tm_to_time64(tm), &calc_tm);
 		wday = calc_tm.tm_wday;
 	}

 	*bcd_year = (bin2bcd(year % 100) | bin2bcd(year / 100) << 8);

 	*st_time = ((tm->tm_mon + 1) << RTC_MON_SHIFT)
 			|	(tm->tm_mday << RTC_MDAY_SHIFT)
 			|	((wday + 1) << RTC_WDAY_SHIFT)
 			|	(tm->tm_hour << RTC_HOUR_SHIFT)
 			|	(tm->tm_min << RTC_MIN_SHIFT)
 			|	(tm->tm_sec << RTC_SEC_SHIFT);

 	return 0;
 }

 /*
  * Convert ST v2 RTC format to Gregorian date.
  */
 static int pl031_stv2_time_to_tm(unsigned long st_time, unsigned long bcd_year,
 	struct rtc_time *tm)
 {
 	tm->tm_year = bcd2bin(bcd_year) + (bcd2bin(bcd_year >> 8) * 100);
 	tm->tm_mon  = ((st_time & RTC_MON_MASK) >> RTC_MON_SHIFT) - 1;
 	tm->tm_mday = ((st_time & RTC_MDAY_MASK) >> RTC_MDAY_SHIFT);
 	tm->tm_wday = ((st_time & RTC_WDAY_MASK) >> RTC_WDAY_SHIFT) - 1;
 	tm->tm_hour = ((st_time & RTC_HOUR_MASK) >> RTC_HOUR_SHIFT);
 	tm->tm_min  = ((st_time & RTC_MIN_MASK) >> RTC_MIN_SHIFT);
 	tm->tm_sec  = ((st_time & RTC_SEC_MASK) >> RTC_SEC_SHIFT);

 	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
 	tm->tm_year -= 1900;

 	return 0;
 }

 static int pl031_stv2_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);

 	pl031_stv2_time_to_tm(readl(ldata->base + RTC_DR),
 			readl(ldata->base + RTC_YDR), tm);

 	return 0;
 }

 static int pl031_stv2_set_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned long time;
 	unsigned long bcd_year;
 	struct pl031_local *ldata = dev_get_drvdata(dev);
 	int ret;

 	ret = pl031_stv2_tm_to_time(dev, tm, &time, &bcd_year);
 	if (ret == 0) {
 		writel(bcd_year, ldata->base + RTC_YLR);
 		writel(time, ldata->base + RTC_LR);
 	}

 	return ret;
 }

 static int pl031_stv2_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);
 	int ret;

 	ret = pl031_stv2_time_to_tm(readl(ldata->base + RTC_MR),
 			readl(ldata->base + RTC_YMR), &alarm->time);

 	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
 	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

 	return ret;
 }

 static int pl031_stv2_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);
 	unsigned long time;
 	unsigned long bcd_year;
 	int ret;

 	ret = pl031_stv2_tm_to_time(dev, &alarm->time,
 				    &time, &bcd_year);
 	if (ret == 0) {
 		writel(bcd_year, ldata->base + RTC_YMR);
 		writel(time, ldata->base + RTC_MR);

 		pl031_alarm_irq_enable(dev, alarm->enabled);
 	}

 	return ret;
 }

 static irqreturn_t pl031_interrupt(int irq, void *dev_id)
 {
 	struct pl031_local *ldata = dev_id;
 	unsigned long rtcmis;
 	unsigned long events = 0;

 	rtcmis = readl(ldata->base + RTC_MIS);
 	if (rtcmis & RTC_BIT_AI) {
 		writel(RTC_BIT_AI, ldata->base + RTC_ICR);
 		events |= (RTC_AF | RTC_IRQF);
 		rtc_update_irq(ldata->rtc, 1, events);

 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static int pl031_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);

 	rtc_time64_to_tm(readl(ldata->base + RTC_DR), tm);

 	return 0;
 }

 static int pl031_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);

 	writel(rtc_tm_to_time64(tm), ldata->base + RTC_LR);

 	return 0;
 }

 static int pl031_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);

 	rtc_time64_to_tm(readl(ldata->base + RTC_MR), &alarm->time);

 	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
 	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

 	return 0;
 }

 static int pl031_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct pl031_local *ldata = dev_get_drvdata(dev);

 	writel(rtc_tm_to_time64(&alarm->time), ldata->base + RTC_MR);
 	pl031_alarm_irq_enable(dev, alarm->enabled);

 	return 0;
 }

 static int pl031_remove(struct amba_device *adev)
 {
 	struct pl031_local *ldata = dev_get_drvdata(&adev->dev);

 	dev_pm_clear_wake_irq(&adev->dev);
 	device_init_wakeup(&adev->dev, false);
 	if (adev->irq[0])
 		free_irq(adev->irq[0], ldata);
 	amba_release_regions(adev);

 	return 0;
 }

 static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 {
 	int ret;
 	struct pl031_local *ldata;
 	struct pl031_vendor_data *vendor = id->data;
 	struct rtc_class_ops *ops;
 	unsigned long time, data;

 	ret = amba_request_regions(adev, NULL);
 	if (ret)
 		goto err_req;

 	ldata = devm_kzalloc(&adev->dev, sizeof(struct pl031_local),
 			     GFP_KERNEL);
 	ops = devm_kmemdup(&adev->dev, &vendor->ops, sizeof(vendor->ops),
 			   GFP_KERNEL);
 	if (!ldata || !ops) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	ldata->vendor = vendor;
 	ldata->base = devm_ioremap(&adev->dev, adev->res.start,
 				   resource_size(&adev->res));
 	if (!ldata->base) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	amba_set_drvdata(adev, ldata);

 	dev_dbg(&adev->dev, "designer ID = 0x%02x\n", amba_manf(adev));
 	dev_dbg(&adev->dev, "revision = 0x%01x\n", amba_rev(adev));

 	data = readl(ldata->base + RTC_CR);
 	/* Enable the clockwatch on ST Variants */
 	if (vendor->clockwatch)
 		data |= RTC_CR_CWEN;
 	else
 		data |= RTC_CR_EN;
 	writel(data, ldata->base + RTC_CR);

 	/*
 	 * On ST PL031 variants, the RTC reset value does not provide correct
 	 * weekday for 2000-01-01. Correct the erroneous sunday to saturday.
 	 */
 	if (vendor->st_weekday) {
 		if (readl(ldata->base + RTC_YDR) == 0x2000) {
 			time = readl(ldata->base + RTC_DR);
 			if ((time &
 			     (RTC_MON_MASK | RTC_MDAY_MASK | RTC_WDAY_MASK))
 			    == 0x02120000) {
 				time = time | (0x7 << RTC_WDAY_SHIFT);
 				writel(0x2000, ldata->base + RTC_YLR);
 				writel(time, ldata->base + RTC_LR);
 			}
 		}
 	}

 	if (!adev->irq[0]) {
 		/* When there's no interrupt, no point in exposing the alarm */
 		ops->read_alarm = NULL;
 		ops->set_alarm = NULL;
 		ops->alarm_irq_enable = NULL;
 	}

 	device_init_wakeup(&adev->dev, true);
 	ldata->rtc = devm_rtc_allocate_device(&adev->dev);
 	if (IS_ERR(ldata->rtc))
 		return PTR_ERR(ldata->rtc);

 	ldata->rtc->ops = ops;
 	ldata->rtc->range_min = vendor->range_min;
 	ldata->rtc->range_max = vendor->range_max;

 	ret = rtc_register_device(ldata->rtc);
 	if (ret)
 		goto out;

 	if (adev->irq[0]) {
 		ret = request_irq(adev->irq[0], pl031_interrupt,
 				  vendor->irqflags, "rtc-pl031", ldata);
 		if (ret)
 			goto out;
 		dev_pm_set_wake_irq(&adev->dev, adev->irq[0]);
 	}
 	return 0;

 out:
 	amba_release_regions(adev);
 err_req:

 	return ret;
 }

 /* Operations for the original ARM version */
 static struct pl031_vendor_data arm_pl031 = {
 	.ops = {
 		.read_time = pl031_read_time,
 		.set_time = pl031_set_time,
 		.read_alarm = pl031_read_alarm,
 		.set_alarm = pl031_set_alarm,
 		.alarm_irq_enable = pl031_alarm_irq_enable,
 	},
 	.range_max = U32_MAX,
 };

 /* The First ST derivative */
 static struct pl031_vendor_data stv1_pl031 = {
 	.ops = {
 		.read_time = pl031_read_time,
 		.set_time = pl031_set_time,
 		.read_alarm = pl031_read_alarm,
 		.set_alarm = pl031_set_alarm,
 		.alarm_irq_enable = pl031_alarm_irq_enable,
 	},
 	.clockwatch = true,
 	.st_weekday = true,
 	.range_max = U32_MAX,
 };

 /* And the second ST derivative */
 static struct pl031_vendor_data stv2_pl031 = {
 	.ops = {
 		.read_time = pl031_stv2_read_time,
 		.set_time = pl031_stv2_set_time,
 		.read_alarm = pl031_stv2_read_alarm,
 		.set_alarm = pl031_stv2_set_alarm,
 		.alarm_irq_enable = pl031_alarm_irq_enable,
 	},
 	.clockwatch = true,
 	.st_weekday = true,
 	/*
 	 * This variant shares the IRQ with another block and must not
 	 * suspend that IRQ line.
 	 * TODO check if it shares with IRQF_NO_SUSPEND user, else we can
 	 * remove IRQF_COND_SUSPEND
 	 */
 	.irqflags = IRQF_SHARED | IRQF_COND_SUSPEND,
 	.range_min = RTC_TIMESTAMP_BEGIN_0000,
 	.range_max = RTC_TIMESTAMP_END_9999,
 };

 static const struct amba_id pl031_ids[] = {
 	{
 		.id = 0x00041031,
 		.mask = 0x000fffff,
 		.data = &arm_pl031,
 	},
 	/* ST Micro variants */
 	{
 		.id = 0x00180031,
 		.mask = 0x00ffffff,
 		.data = &stv1_pl031,
 	},
 	{
 		.id = 0x00280031,
 		.mask = 0x00ffffff,
 		.data = &stv2_pl031,
 	},
 	{0, 0},
 };

 MODULE_DEVICE_TABLE(amba, pl031_ids);

 static struct amba_driver pl031_driver = {
 	.drv = {
 		.name = "rtc-pl031",
 	},
 	.id_table = pl031_ids,
 	.probe = pl031_probe,
 	.remove = pl031_remove,
 };

 module_amba_driver(pl031_driver);

 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 MODULE_DESCRIPTION("ARM AMBA PL031 RTC Driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* drivers/rtc/rtc-pl031.c
	*
	* Real Time Clock interface for ARM AMBA PrimeCell 031 RTC
	*
	* Author: Deepak Saxena <dsaxena@plexity.net>
	*
	* Copyright 2006 (c) MontaVista Software, Inc.
	*
	* Author: Mian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
	* Copyright 2010 (c) ST-Ericsson AB
	*/
	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/amba/bus.h>
	#include <linux/io.h>
	#include <linux/bcd.h>
	#include <linux/delay.h>
	#include <linux/pm_wakeirq.h>
	#include <linux/slab.h>

	/*
	* Register definitions
	*/
	#define RTC_DR 0x00 /* Data read register */
	#define RTC_MR 0x04 /* Match register */
	#define RTC_LR 0x08 /* Data load register */
	#define RTC_CR 0x0c /* Control register */
	#define RTC_IMSC 0x10 /* Interrupt mask and set register */
	#define RTC_RIS 0x14 /* Raw interrupt status register */
	#define RTC_MIS 0x18 /* Masked interrupt status register */
	#define RTC_ICR 0x1c /* Interrupt clear register */
	/* ST variants have additional timer functionality */
	#define RTC_TDR 0x20 /* Timer data read register */
	#define RTC_TLR 0x24 /* Timer data load register */
	#define RTC_TCR 0x28 /* Timer control register */
	#define RTC_YDR 0x30 /* Year data read register */
	#define RTC_YMR 0x34 /* Year match register */
	#define RTC_YLR 0x38 /* Year data load register */

	#define RTC_CR_EN (1 << 0) /* counter enable bit */
	#define RTC_CR_CWEN (1 << 26) /* Clockwatch enable bit */

	#define RTC_TCR_EN (1 << 1) /* Periodic timer enable bit */

	/* Common bit definitions for Interrupt status and control registers */
	#define RTC_BIT_AI (1 << 0) /* Alarm interrupt bit */
	#define RTC_BIT_PI (1 << 1) /* Periodic interrupt bit. ST variants only. */

	/* Common bit definations for ST v2 for reading/writing time */
	#define RTC_SEC_SHIFT 0
	#define RTC_SEC_MASK (0x3F << RTC_SEC_SHIFT) /* Second [0-59] */
	#define RTC_MIN_SHIFT 6
	#define RTC_MIN_MASK (0x3F << RTC_MIN_SHIFT) /* Minute [0-59] */
	#define RTC_HOUR_SHIFT 12
	#define RTC_HOUR_MASK (0x1F << RTC_HOUR_SHIFT) /* Hour [0-23] */
	#define RTC_WDAY_SHIFT 17
	#define RTC_WDAY_MASK (0x7 << RTC_WDAY_SHIFT) /* Day of Week [1-7] 1=Sunday */
	#define RTC_MDAY_SHIFT 20
	#define RTC_MDAY_MASK (0x1F << RTC_MDAY_SHIFT) /* Day of Month [1-31] */
	#define RTC_MON_SHIFT 25
	#define RTC_MON_MASK (0xF << RTC_MON_SHIFT) /* Month [1-12] 1=January */

	#define RTC_TIMER_FREQ 32768

	/**
	* struct pl031_vendor_data - per-vendor variations
	* @ops: the vendor-specific operations used on this silicon version
	* @clockwatch: if this is an ST Microelectronics silicon version with a
	* clockwatch function
	* @st_weekday: if this is an ST Microelectronics silicon version that need
	* the weekday fix
	* @irqflags: special IRQ flags per variant
	*/
	struct pl031_vendor_data {
	struct rtc_class_ops ops;
	bool clockwatch;
	bool st_weekday;
	unsigned long irqflags;
	time64_t range_min;
	timeu64_t range_max;
	};

	struct pl031_local {
	struct pl031_vendor_data *vendor;
	struct rtc_device *rtc;
	void __iomem *base;
	};

	static int pl031_alarm_irq_enable(struct device *dev,
	unsigned int enabled)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);
	unsigned long imsc;

	/* Clear any pending alarm interrupts. */
	writel(RTC_BIT_AI, ldata->base + RTC_ICR);

	imsc = readl(ldata->base + RTC_IMSC);

	if (enabled == 1)
	writel(imsc \| RTC_BIT_AI, ldata->base + RTC_IMSC);
	else
	writel(imsc & ~RTC_BIT_AI, ldata->base + RTC_IMSC);

	return 0;
	}

	/*
	* Convert Gregorian date to ST v2 RTC format.
	*/
	static int pl031_stv2_tm_to_time(struct device *dev,
	struct rtc_time tm, unsigned long st_time,
	unsigned long *bcd_year)
	{
	int year = tm->tm_year + 1900;
	int wday = tm->tm_wday;

	/* wday masking is not working in hardware so wday must be valid */
	if (wday < -1 \|\| wday > 6) {
	dev_err(dev, "invalid wday value %d\n", tm->tm_wday);
	return -EINVAL;
	} else if (wday == -1) {
	/* wday is not provided, calculate it here */
	struct rtc_time calc_tm;

	rtc_time64_to_tm(rtc_tm_to_time64(tm), &calc_tm);
	wday = calc_tm.tm_wday;
	}

	*bcd_year = (bin2bcd(year % 100) \| bin2bcd(year / 100) << 8);

	*st_time = ((tm->tm_mon + 1) << RTC_MON_SHIFT)
	\| (tm->tm_mday << RTC_MDAY_SHIFT)
	\| ((wday + 1) << RTC_WDAY_SHIFT)
	\| (tm->tm_hour << RTC_HOUR_SHIFT)
	\| (tm->tm_min << RTC_MIN_SHIFT)
	\| (tm->tm_sec << RTC_SEC_SHIFT);

	return 0;
	}

	/*
	* Convert ST v2 RTC format to Gregorian date.
	*/
	static int pl031_stv2_time_to_tm(unsigned long st_time, unsigned long bcd_year,
	struct rtc_time *tm)
	{
	tm->tm_year = bcd2bin(bcd_year) + (bcd2bin(bcd_year >> 8) * 100);
	tm->tm_mon = ((st_time & RTC_MON_MASK) >> RTC_MON_SHIFT) - 1;
	tm->tm_mday = ((st_time & RTC_MDAY_MASK) >> RTC_MDAY_SHIFT);
	tm->tm_wday = ((st_time & RTC_WDAY_MASK) >> RTC_WDAY_SHIFT) - 1;
	tm->tm_hour = ((st_time & RTC_HOUR_MASK) >> RTC_HOUR_SHIFT);
	tm->tm_min = ((st_time & RTC_MIN_MASK) >> RTC_MIN_SHIFT);
	tm->tm_sec = ((st_time & RTC_SEC_MASK) >> RTC_SEC_SHIFT);

	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
	tm->tm_year -= 1900;

	return 0;
	}

	static int pl031_stv2_read_time(struct device dev, struct rtc_time tm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);

	pl031_stv2_time_to_tm(readl(ldata->base + RTC_DR),
	readl(ldata->base + RTC_YDR), tm);

	return 0;
	}

	static int pl031_stv2_set_time(struct device dev, struct rtc_time tm)
	{
	unsigned long time;
	unsigned long bcd_year;
	struct pl031_local *ldata = dev_get_drvdata(dev);
	int ret;

	ret = pl031_stv2_tm_to_time(dev, tm, &time, &bcd_year);
	if (ret == 0) {
	writel(bcd_year, ldata->base + RTC_YLR);
	writel(time, ldata->base + RTC_LR);
	}

	return ret;
	}

	static int pl031_stv2_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);
	int ret;

	ret = pl031_stv2_time_to_tm(readl(ldata->base + RTC_MR),
	readl(ldata->base + RTC_YMR), &alarm->time);

	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

	return ret;
	}

	static int pl031_stv2_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);
	unsigned long time;
	unsigned long bcd_year;
	int ret;

	ret = pl031_stv2_tm_to_time(dev, &alarm->time,
	&time, &bcd_year);
	if (ret == 0) {
	writel(bcd_year, ldata->base + RTC_YMR);
	writel(time, ldata->base + RTC_MR);

	pl031_alarm_irq_enable(dev, alarm->enabled);
	}

	return ret;
	}

	static irqreturn_t pl031_interrupt(int irq, void *dev_id)
	{
	struct pl031_local *ldata = dev_id;
	unsigned long rtcmis;
	unsigned long events = 0;

	rtcmis = readl(ldata->base + RTC_MIS);
	if (rtcmis & RTC_BIT_AI) {
	writel(RTC_BIT_AI, ldata->base + RTC_ICR);
	events \|= (RTC_AF \| RTC_IRQF);
	rtc_update_irq(ldata->rtc, 1, events);

	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static int pl031_read_time(struct device dev, struct rtc_time tm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);

	rtc_time64_to_tm(readl(ldata->base + RTC_DR), tm);

	return 0;
	}

	static int pl031_set_time(struct device dev, struct rtc_time tm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);

	writel(rtc_tm_to_time64(tm), ldata->base + RTC_LR);

	return 0;
	}

	static int pl031_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);

	rtc_time64_to_tm(readl(ldata->base + RTC_MR), &alarm->time);

	alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
	alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

	return 0;
	}

	static int pl031_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct pl031_local *ldata = dev_get_drvdata(dev);

	writel(rtc_tm_to_time64(&alarm->time), ldata->base + RTC_MR);
	pl031_alarm_irq_enable(dev, alarm->enabled);

	return 0;
	}

	static int pl031_remove(struct amba_device *adev)
	{
	struct pl031_local *ldata = dev_get_drvdata(&adev->dev);

	dev_pm_clear_wake_irq(&adev->dev);
	device_init_wakeup(&adev->dev, false);
	if (adev->irq[0])
	free_irq(adev->irq[0], ldata);
	amba_release_regions(adev);

	return 0;
	}

	static int pl031_probe(struct amba_device adev, const struct amba_id id)
	{
	int ret;
	struct pl031_local *ldata;
	struct pl031_vendor_data *vendor = id->data;
	struct rtc_class_ops *ops;
	unsigned long time, data;

	ret = amba_request_regions(adev, NULL);
	if (ret)
	goto err_req;

	ldata = devm_kzalloc(&adev->dev, sizeof(struct pl031_local),
	GFP_KERNEL);
	ops = devm_kmemdup(&adev->dev, &vendor->ops, sizeof(vendor->ops),
	GFP_KERNEL);
	if (!ldata \|\| !ops) {
	ret = -ENOMEM;
	goto out;
	}

	ldata->vendor = vendor;
	ldata->base = devm_ioremap(&adev->dev, adev->res.start,
	resource_size(&adev->res));
	if (!ldata->base) {
	ret = -ENOMEM;
	goto out;
	}

	amba_set_drvdata(adev, ldata);

	dev_dbg(&adev->dev, "designer ID = 0x%02x\n", amba_manf(adev));
	dev_dbg(&adev->dev, "revision = 0x%01x\n", amba_rev(adev));

	data = readl(ldata->base + RTC_CR);
	/* Enable the clockwatch on ST Variants */
	if (vendor->clockwatch)
	data \|= RTC_CR_CWEN;
	else
	data \|= RTC_CR_EN;
	writel(data, ldata->base + RTC_CR);

	/*
	* On ST PL031 variants, the RTC reset value does not provide correct
	* weekday for 2000-01-01. Correct the erroneous sunday to saturday.
	*/
	if (vendor->st_weekday) {
	if (readl(ldata->base + RTC_YDR) == 0x2000) {
	time = readl(ldata->base + RTC_DR);
	if ((time &
	(RTC_MON_MASK \| RTC_MDAY_MASK \| RTC_WDAY_MASK))
	== 0x02120000) {
	time = time \| (0x7 << RTC_WDAY_SHIFT);
	writel(0x2000, ldata->base + RTC_YLR);
	writel(time, ldata->base + RTC_LR);
	}
	}
	}

	if (!adev->irq[0]) {
	/* When there's no interrupt, no point in exposing the alarm */
	ops->read_alarm = NULL;
	ops->set_alarm = NULL;
	ops->alarm_irq_enable = NULL;
	}

	device_init_wakeup(&adev->dev, true);
	ldata->rtc = devm_rtc_allocate_device(&adev->dev);
	if (IS_ERR(ldata->rtc))
	return PTR_ERR(ldata->rtc);

	ldata->rtc->ops = ops;
	ldata->rtc->range_min = vendor->range_min;
	ldata->rtc->range_max = vendor->range_max;

	ret = rtc_register_device(ldata->rtc);
	if (ret)
	goto out;

	if (adev->irq[0]) {
	ret = request_irq(adev->irq[0], pl031_interrupt,
	vendor->irqflags, "rtc-pl031", ldata);
	if (ret)
	goto out;
	dev_pm_set_wake_irq(&adev->dev, adev->irq[0]);
	}
	return 0;

	out:
	amba_release_regions(adev);
	err_req:

	return ret;
	}

	/* Operations for the original ARM version */
	static struct pl031_vendor_data arm_pl031 = {
	.ops = {
	.read_time = pl031_read_time,
	.set_time = pl031_set_time,
	.read_alarm = pl031_read_alarm,
	.set_alarm = pl031_set_alarm,
	.alarm_irq_enable = pl031_alarm_irq_enable,
	},
	.range_max = U32_MAX,
	};

	/* The First ST derivative */
	static struct pl031_vendor_data stv1_pl031 = {
	.ops = {
	.read_time = pl031_read_time,
	.set_time = pl031_set_time,
	.read_alarm = pl031_read_alarm,
	.set_alarm = pl031_set_alarm,
	.alarm_irq_enable = pl031_alarm_irq_enable,
	},
	.clockwatch = true,
	.st_weekday = true,
	.range_max = U32_MAX,
	};

	/* And the second ST derivative */
	static struct pl031_vendor_data stv2_pl031 = {
	.ops = {
	.read_time = pl031_stv2_read_time,
	.set_time = pl031_stv2_set_time,
	.read_alarm = pl031_stv2_read_alarm,
	.set_alarm = pl031_stv2_set_alarm,
	.alarm_irq_enable = pl031_alarm_irq_enable,
	},
	.clockwatch = true,
	.st_weekday = true,
	/*
	* This variant shares the IRQ with another block and must not
	* suspend that IRQ line.
	* TODO check if it shares with IRQF_NO_SUSPEND user, else we can
	* remove IRQF_COND_SUSPEND
	*/
	.irqflags = IRQF_SHARED \| IRQF_COND_SUSPEND,
	.range_min = RTC_TIMESTAMP_BEGIN_0000,
	.range_max = RTC_TIMESTAMP_END_9999,
	};

	static const struct amba_id pl031_ids[] = {
	{
	.id = 0x00041031,
	.mask = 0x000fffff,
	.data = &arm_pl031,
	},
	/* ST Micro variants */
	{
	.id = 0x00180031,
	.mask = 0x00ffffff,
	.data = &stv1_pl031,
	},
	{
	.id = 0x00280031,
	.mask = 0x00ffffff,
	.data = &stv2_pl031,
	},
	{0, 0},
	};

	MODULE_DEVICE_TABLE(amba, pl031_ids);

	static struct amba_driver pl031_driver = {
	.drv = {
	.name = "rtc-pl031",
	},
	.id_table = pl031_ids,
	.probe = pl031_probe,
	.remove = pl031_remove,
	};

	module_amba_driver(pl031_driver);

	MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
	MODULE_DESCRIPTION("ARM AMBA PL031 RTC Driver");
	MODULE_LICENSE("GPL");