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

 // SPDX-License-Identifier: GPL-2.0

 /*
  * Copyright 2019 Cadence
  *
  * Authors:
  *  Jan Kotas <jank@cadence.com>
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/io.h>
 #include <linux/rtc.h>
 #include <linux/clk.h>
 #include <linux/bcd.h>
 #include <linux/bitfield.h>
 #include <linux/interrupt.h>
 #include <linux/pm_wakeirq.h>

 /* Registers */
 #define CDNS_RTC_CTLR		0x00
 #define CDNS_RTC_HMR		0x04
 #define CDNS_RTC_TIMR		0x08
 #define CDNS_RTC_CALR		0x0C
 #define CDNS_RTC_TIMAR		0x10
 #define CDNS_RTC_CALAR		0x14
 #define CDNS_RTC_AENR		0x18
 #define CDNS_RTC_EFLR		0x1C
 #define CDNS_RTC_IENR		0x20
 #define CDNS_RTC_IDISR		0x24
 #define CDNS_RTC_IMSKR		0x28
 #define CDNS_RTC_STSR		0x2C
 #define CDNS_RTC_KRTCR		0x30

 /* Control */
 #define CDNS_RTC_CTLR_TIME	BIT(0)
 #define CDNS_RTC_CTLR_CAL	BIT(1)
 #define CDNS_RTC_CTLR_TIME_CAL	(CDNS_RTC_CTLR_TIME | CDNS_RTC_CTLR_CAL)

 /* Status */
 #define CDNS_RTC_STSR_VT	BIT(0)
 #define CDNS_RTC_STSR_VC	BIT(1)
 #define CDNS_RTC_STSR_VTA	BIT(2)
 #define CDNS_RTC_STSR_VCA	BIT(3)
 #define CDNS_RTC_STSR_VT_VC	(CDNS_RTC_STSR_VT | CDNS_RTC_STSR_VC)
 #define CDNS_RTC_STSR_VTA_VCA	(CDNS_RTC_STSR_VTA | CDNS_RTC_STSR_VCA)

 /* Keep RTC */
 #define CDNS_RTC_KRTCR_KRTC	BIT(0)

 /* Alarm, Event, Interrupt */
 #define CDNS_RTC_AEI_HOS	BIT(0)
 #define CDNS_RTC_AEI_SEC	BIT(1)
 #define CDNS_RTC_AEI_MIN	BIT(2)
 #define CDNS_RTC_AEI_HOUR	BIT(3)
 #define CDNS_RTC_AEI_DATE	BIT(4)
 #define CDNS_RTC_AEI_MNTH	BIT(5)
 #define CDNS_RTC_AEI_ALRM	BIT(6)

 /* Time */
 #define CDNS_RTC_TIME_H		GENMASK(7, 0)
 #define CDNS_RTC_TIME_S		GENMASK(14, 8)
 #define CDNS_RTC_TIME_M		GENMASK(22, 16)
 #define CDNS_RTC_TIME_HR	GENMASK(29, 24)
 #define CDNS_RTC_TIME_PM	BIT(30)
 #define CDNS_RTC_TIME_CH	BIT(31)

 /* Calendar */
 #define CDNS_RTC_CAL_DAY	GENMASK(2, 0)
 #define CDNS_RTC_CAL_M		GENMASK(7, 3)
 #define CDNS_RTC_CAL_D		GENMASK(13, 8)
 #define CDNS_RTC_CAL_Y		GENMASK(23, 16)
 #define CDNS_RTC_CAL_C		GENMASK(29, 24)
 #define CDNS_RTC_CAL_CH		BIT(31)

 #define CDNS_RTC_MAX_REGS_TRIES	3

 struct cdns_rtc {
 	struct rtc_device *rtc_dev;
 	struct clk *pclk;
 	struct clk *ref_clk;
 	void __iomem *regs;
 	int irq;
 };

 static void cdns_rtc_set_enabled(struct cdns_rtc *crtc, bool enabled)
 {
 	u32 reg = enabled ? 0x0 : CDNS_RTC_CTLR_TIME_CAL;

 	writel(reg, crtc->regs + CDNS_RTC_CTLR);
 }

 static bool cdns_rtc_get_enabled(struct cdns_rtc *crtc)
 {
 	return !(readl(crtc->regs + CDNS_RTC_CTLR) & CDNS_RTC_CTLR_TIME_CAL);
 }

 static irqreturn_t cdns_rtc_irq_handler(int irq, void *id)
 {
 	struct device *dev = id;
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);

 	/* Reading the register clears it */
 	if (!(readl(crtc->regs + CDNS_RTC_EFLR) & CDNS_RTC_AEI_ALRM))
 		return IRQ_NONE;

 	rtc_update_irq(crtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
 	return IRQ_HANDLED;
 }

 static u32 cdns_rtc_time2reg(struct rtc_time *tm)
 {
 	return FIELD_PREP(CDNS_RTC_TIME_S,  bin2bcd(tm->tm_sec))
 	     | FIELD_PREP(CDNS_RTC_TIME_M,  bin2bcd(tm->tm_min))
 	     | FIELD_PREP(CDNS_RTC_TIME_HR, bin2bcd(tm->tm_hour));
 }

 static void cdns_rtc_reg2time(u32 reg, struct rtc_time *tm)
 {
 	tm->tm_sec  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_S, reg));
 	tm->tm_min  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_M, reg));
 	tm->tm_hour = bcd2bin(FIELD_GET(CDNS_RTC_TIME_HR, reg));
 }

 static int cdns_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);
 	u32 reg;

 	/* If the RTC is disabled, assume the values are invalid */
 	if (!cdns_rtc_get_enabled(crtc))
 		return -EINVAL;

 	cdns_rtc_set_enabled(crtc, false);

 	reg = readl(crtc->regs + CDNS_RTC_TIMR);
 	cdns_rtc_reg2time(reg, tm);

 	reg = readl(crtc->regs + CDNS_RTC_CALR);
 	tm->tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
 	tm->tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
 	tm->tm_year = bcd2bin(FIELD_GET(CDNS_RTC_CAL_Y, reg))
 		    + bcd2bin(FIELD_GET(CDNS_RTC_CAL_C, reg)) * 100 - 1900;
 	tm->tm_wday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_DAY, reg)) - 1;

 	cdns_rtc_set_enabled(crtc, true);
 	return 0;
 }

 static int cdns_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);
 	u32 timr, calr, stsr;
 	int ret = -EIO;
 	int year = tm->tm_year + 1900;
 	int tries;

 	cdns_rtc_set_enabled(crtc, false);

 	timr = cdns_rtc_time2reg(tm);

 	calr = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(tm->tm_mday))
 	     | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(tm->tm_mon + 1))
 	     | FIELD_PREP(CDNS_RTC_CAL_Y, bin2bcd(year % 100))
 	     | FIELD_PREP(CDNS_RTC_CAL_C, bin2bcd(year / 100))
 	     | FIELD_PREP(CDNS_RTC_CAL_DAY, tm->tm_wday + 1);

 	/* Update registers, check valid flags */
 	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
 		writel(timr, crtc->regs + CDNS_RTC_TIMR);
 		writel(calr, crtc->regs + CDNS_RTC_CALR);
 		stsr = readl(crtc->regs + CDNS_RTC_STSR);

 		if ((stsr & CDNS_RTC_STSR_VT_VC) == CDNS_RTC_STSR_VT_VC) {
 			ret = 0;
 			break;
 		}
 	}

 	cdns_rtc_set_enabled(crtc, true);
 	return ret;
 }

 static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);

 	if (enabled) {
 		writel((CDNS_RTC_AEI_SEC | CDNS_RTC_AEI_MIN | CDNS_RTC_AEI_HOUR
 			| CDNS_RTC_AEI_DATE | CDNS_RTC_AEI_MNTH),
 		       crtc->regs + CDNS_RTC_AENR);
 		writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
 	} else {
 		writel(0, crtc->regs + CDNS_RTC_AENR);
 		writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
 	}

 	return 0;
 }

 static int cdns_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);
 	u32 reg;

 	reg = readl(crtc->regs + CDNS_RTC_TIMAR);
 	cdns_rtc_reg2time(reg, &alarm->time);

 	reg = readl(crtc->regs + CDNS_RTC_CALAR);
 	alarm->time.tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
 	alarm->time.tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;

 	return 0;
 }

 static int cdns_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);
 	int ret = -EIO;
 	int tries;
 	u32 timar, calar, stsr;

 	cdns_rtc_alarm_irq_enable(dev, 0);

 	timar = cdns_rtc_time2reg(&alarm->time);
 	calar = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(alarm->time.tm_mday))
 	      | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(alarm->time.tm_mon + 1));

 	/* Update registers, check valid alarm flags */
 	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
 		writel(timar, crtc->regs + CDNS_RTC_TIMAR);
 		writel(calar, crtc->regs + CDNS_RTC_CALAR);
 		stsr = readl(crtc->regs + CDNS_RTC_STSR);

 		if ((stsr & CDNS_RTC_STSR_VTA_VCA) == CDNS_RTC_STSR_VTA_VCA) {
 			ret = 0;
 			break;
 		}
 	}

 	if (!ret)
 		cdns_rtc_alarm_irq_enable(dev, alarm->enabled);
 	return ret;
 }

 static const struct rtc_class_ops cdns_rtc_ops = {
 	.read_time	= cdns_rtc_read_time,
 	.set_time	= cdns_rtc_set_time,
 	.read_alarm	= cdns_rtc_read_alarm,
 	.set_alarm	= cdns_rtc_set_alarm,
 	.alarm_irq_enable = cdns_rtc_alarm_irq_enable,
 };

 static int cdns_rtc_probe(struct platform_device *pdev)
 {
 	struct cdns_rtc *crtc;
 	int ret;
 	unsigned long ref_clk_freq;

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

 	crtc->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(crtc->regs))
 		return PTR_ERR(crtc->regs);

 	crtc->irq = platform_get_irq(pdev, 0);
 	if (crtc->irq < 0)
 		return -EINVAL;

 	crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
 	if (IS_ERR(crtc->pclk)) {
 		ret = PTR_ERR(crtc->pclk);
 		dev_err(&pdev->dev,
 			"Failed to retrieve the peripheral clock, %d\n", ret);
 		return ret;
 	}

 	crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
 	if (IS_ERR(crtc->ref_clk)) {
 		ret = PTR_ERR(crtc->ref_clk);
 		dev_err(&pdev->dev,
 			"Failed to retrieve the reference clock, %d\n", ret);
 		return ret;
 	}

 	crtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(crtc->rtc_dev))
 		return PTR_ERR(crtc->rtc_dev);

 	platform_set_drvdata(pdev, crtc);

 	ret = clk_prepare_enable(crtc->pclk);
 	if (ret) {
 		dev_err(&pdev->dev,
 			"Failed to enable the peripheral clock, %d\n", ret);
 		return ret;
 	}

 	ret = clk_prepare_enable(crtc->ref_clk);
 	if (ret) {
 		dev_err(&pdev->dev,
 			"Failed to enable the reference clock, %d\n", ret);
 		goto err_disable_pclk;
 	}

 	ref_clk_freq = clk_get_rate(crtc->ref_clk);
 	if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
 		dev_err(&pdev->dev,
 			"Invalid reference clock frequency %lu Hz.\n",
 			ref_clk_freq);
 		ret = -EINVAL;
 		goto err_disable_ref_clk;
 	}

 	ret = devm_request_irq(&pdev->dev, crtc->irq,
 			       cdns_rtc_irq_handler, 0,
 			       dev_name(&pdev->dev), &pdev->dev);
 	if (ret) {
 		dev_err(&pdev->dev,
 			"Failed to request interrupt for the device, %d\n",
 			ret);
 		goto err_disable_ref_clk;
 	}

 	/* The RTC supports 01.01.1900 - 31.12.2999 */
 	crtc->rtc_dev->range_min = mktime64(1900,  1,  1,  0,  0,  0);
 	crtc->rtc_dev->range_max = mktime64(2999, 12, 31, 23, 59, 59);

 	crtc->rtc_dev->ops = &cdns_rtc_ops;
 	device_init_wakeup(&pdev->dev, true);

 	/* Always use 24-hour mode and keep the RTC values */
 	writel(0, crtc->regs + CDNS_RTC_HMR);
 	writel(CDNS_RTC_KRTCR_KRTC, crtc->regs + CDNS_RTC_KRTCR);

 	ret = devm_rtc_register_device(crtc->rtc_dev);
 	if (ret)
 		goto err_disable_wakeup;

 	return 0;

 err_disable_wakeup:
 	device_init_wakeup(&pdev->dev, false);

 err_disable_ref_clk:
 	clk_disable_unprepare(crtc->ref_clk);

 err_disable_pclk:
 	clk_disable_unprepare(crtc->pclk);

 	return ret;
 }

 static void cdns_rtc_remove(struct platform_device *pdev)
 {
 	struct cdns_rtc *crtc = platform_get_drvdata(pdev);

 	cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
 	device_init_wakeup(&pdev->dev, 0);

 	clk_disable_unprepare(crtc->pclk);
 	clk_disable_unprepare(crtc->ref_clk);
 }

 #ifdef CONFIG_PM_SLEEP
 static int cdns_rtc_suspend(struct device *dev)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev))
 		enable_irq_wake(crtc->irq);

 	return 0;
 }

 static int cdns_rtc_resume(struct device *dev)
 {
 	struct cdns_rtc *crtc = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev))
 		disable_irq_wake(crtc->irq);

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);

 static const struct of_device_id cdns_rtc_of_match[] = {
 	{ .compatible = "cdns,rtc-r109v3" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);

 static struct platform_driver cdns_rtc_driver = {
 	.driver = {
 		.name = "cdns-rtc",
 		.of_match_table = cdns_rtc_of_match,
 		.pm = &cdns_rtc_pm_ops,
 	},
 	.probe = cdns_rtc_probe,
 	.remove = cdns_rtc_remove,
 };
 module_platform_driver(cdns_rtc_driver);

 MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
 MODULE_DESCRIPTION("Cadence RTC driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:cdns-rtc");
	// SPDX-License-Identifier: GPL-2.0

	/*
	* Copyright 2019 Cadence
	*
	* Authors:
	* Jan Kotas <jank@cadence.com>
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/of.h>
	#include <linux/io.h>
	#include <linux/rtc.h>
	#include <linux/clk.h>
	#include <linux/bcd.h>
	#include <linux/bitfield.h>
	#include <linux/interrupt.h>
	#include <linux/pm_wakeirq.h>

	/* Registers */
	#define CDNS_RTC_CTLR 0x00
	#define CDNS_RTC_HMR 0x04
	#define CDNS_RTC_TIMR 0x08
	#define CDNS_RTC_CALR 0x0C
	#define CDNS_RTC_TIMAR 0x10
	#define CDNS_RTC_CALAR 0x14
	#define CDNS_RTC_AENR 0x18
	#define CDNS_RTC_EFLR 0x1C
	#define CDNS_RTC_IENR 0x20
	#define CDNS_RTC_IDISR 0x24
	#define CDNS_RTC_IMSKR 0x28
	#define CDNS_RTC_STSR 0x2C
	#define CDNS_RTC_KRTCR 0x30

	/* Control */
	#define CDNS_RTC_CTLR_TIME BIT(0)
	#define CDNS_RTC_CTLR_CAL BIT(1)
	#define CDNS_RTC_CTLR_TIME_CAL (CDNS_RTC_CTLR_TIME \| CDNS_RTC_CTLR_CAL)

	/* Status */
	#define CDNS_RTC_STSR_VT BIT(0)
	#define CDNS_RTC_STSR_VC BIT(1)
	#define CDNS_RTC_STSR_VTA BIT(2)
	#define CDNS_RTC_STSR_VCA BIT(3)
	#define CDNS_RTC_STSR_VT_VC (CDNS_RTC_STSR_VT \| CDNS_RTC_STSR_VC)
	#define CDNS_RTC_STSR_VTA_VCA (CDNS_RTC_STSR_VTA \| CDNS_RTC_STSR_VCA)

	/* Keep RTC */
	#define CDNS_RTC_KRTCR_KRTC BIT(0)

	/* Alarm, Event, Interrupt */
	#define CDNS_RTC_AEI_HOS BIT(0)
	#define CDNS_RTC_AEI_SEC BIT(1)
	#define CDNS_RTC_AEI_MIN BIT(2)
	#define CDNS_RTC_AEI_HOUR BIT(3)
	#define CDNS_RTC_AEI_DATE BIT(4)
	#define CDNS_RTC_AEI_MNTH BIT(5)
	#define CDNS_RTC_AEI_ALRM BIT(6)

	/* Time */
	#define CDNS_RTC_TIME_H GENMASK(7, 0)
	#define CDNS_RTC_TIME_S GENMASK(14, 8)
	#define CDNS_RTC_TIME_M GENMASK(22, 16)
	#define CDNS_RTC_TIME_HR GENMASK(29, 24)
	#define CDNS_RTC_TIME_PM BIT(30)
	#define CDNS_RTC_TIME_CH BIT(31)

	/* Calendar */
	#define CDNS_RTC_CAL_DAY GENMASK(2, 0)
	#define CDNS_RTC_CAL_M GENMASK(7, 3)
	#define CDNS_RTC_CAL_D GENMASK(13, 8)
	#define CDNS_RTC_CAL_Y GENMASK(23, 16)
	#define CDNS_RTC_CAL_C GENMASK(29, 24)
	#define CDNS_RTC_CAL_CH BIT(31)

	#define CDNS_RTC_MAX_REGS_TRIES 3

	struct cdns_rtc {
	struct rtc_device *rtc_dev;
	struct clk *pclk;
	struct clk *ref_clk;
	void __iomem *regs;
	int irq;
	};

	static void cdns_rtc_set_enabled(struct cdns_rtc *crtc, bool enabled)
	{
	u32 reg = enabled ? 0x0 : CDNS_RTC_CTLR_TIME_CAL;

	writel(reg, crtc->regs + CDNS_RTC_CTLR);
	}

	static bool cdns_rtc_get_enabled(struct cdns_rtc *crtc)
	{
	return !(readl(crtc->regs + CDNS_RTC_CTLR) & CDNS_RTC_CTLR_TIME_CAL);
	}

	static irqreturn_t cdns_rtc_irq_handler(int irq, void *id)
	{
	struct device *dev = id;
	struct cdns_rtc *crtc = dev_get_drvdata(dev);

	/* Reading the register clears it */
	if (!(readl(crtc->regs + CDNS_RTC_EFLR) & CDNS_RTC_AEI_ALRM))
	return IRQ_NONE;

	rtc_update_irq(crtc->rtc_dev, 1, RTC_IRQF \| RTC_AF);
	return IRQ_HANDLED;
	}

	static u32 cdns_rtc_time2reg(struct rtc_time *tm)
	{
	return FIELD_PREP(CDNS_RTC_TIME_S, bin2bcd(tm->tm_sec))
	\| FIELD_PREP(CDNS_RTC_TIME_M, bin2bcd(tm->tm_min))
	\| FIELD_PREP(CDNS_RTC_TIME_HR, bin2bcd(tm->tm_hour));
	}

	static void cdns_rtc_reg2time(u32 reg, struct rtc_time *tm)
	{
	tm->tm_sec = bcd2bin(FIELD_GET(CDNS_RTC_TIME_S, reg));
	tm->tm_min = bcd2bin(FIELD_GET(CDNS_RTC_TIME_M, reg));
	tm->tm_hour = bcd2bin(FIELD_GET(CDNS_RTC_TIME_HR, reg));
	}

	static int cdns_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);
	u32 reg;

	/* If the RTC is disabled, assume the values are invalid */
	if (!cdns_rtc_get_enabled(crtc))
	return -EINVAL;

	cdns_rtc_set_enabled(crtc, false);

	reg = readl(crtc->regs + CDNS_RTC_TIMR);
	cdns_rtc_reg2time(reg, tm);

	reg = readl(crtc->regs + CDNS_RTC_CALR);
	tm->tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
	tm->tm_mon = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
	tm->tm_year = bcd2bin(FIELD_GET(CDNS_RTC_CAL_Y, reg))
	+ bcd2bin(FIELD_GET(CDNS_RTC_CAL_C, reg)) * 100 - 1900;
	tm->tm_wday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_DAY, reg)) - 1;

	cdns_rtc_set_enabled(crtc, true);
	return 0;
	}

	static int cdns_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);
	u32 timr, calr, stsr;
	int ret = -EIO;
	int year = tm->tm_year + 1900;
	int tries;

	cdns_rtc_set_enabled(crtc, false);

	timr = cdns_rtc_time2reg(tm);

	calr = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(tm->tm_mday))
	\| FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(tm->tm_mon + 1))
	\| FIELD_PREP(CDNS_RTC_CAL_Y, bin2bcd(year % 100))
	\| FIELD_PREP(CDNS_RTC_CAL_C, bin2bcd(year / 100))
	\| FIELD_PREP(CDNS_RTC_CAL_DAY, tm->tm_wday + 1);

	/* Update registers, check valid flags */
	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
	writel(timr, crtc->regs + CDNS_RTC_TIMR);
	writel(calr, crtc->regs + CDNS_RTC_CALR);
	stsr = readl(crtc->regs + CDNS_RTC_STSR);

	if ((stsr & CDNS_RTC_STSR_VT_VC) == CDNS_RTC_STSR_VT_VC) {
	ret = 0;
	break;
	}
	}

	cdns_rtc_set_enabled(crtc, true);
	return ret;
	}

	static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);

	if (enabled) {
	writel((CDNS_RTC_AEI_SEC \| CDNS_RTC_AEI_MIN \| CDNS_RTC_AEI_HOUR
	\| CDNS_RTC_AEI_DATE \| CDNS_RTC_AEI_MNTH),
	crtc->regs + CDNS_RTC_AENR);
	writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
	} else {
	writel(0, crtc->regs + CDNS_RTC_AENR);
	writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
	}

	return 0;
	}

	static int cdns_rtc_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);
	u32 reg;

	reg = readl(crtc->regs + CDNS_RTC_TIMAR);
	cdns_rtc_reg2time(reg, &alarm->time);

	reg = readl(crtc->regs + CDNS_RTC_CALAR);
	alarm->time.tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
	alarm->time.tm_mon = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;

	return 0;
	}

	static int cdns_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);
	int ret = -EIO;
	int tries;
	u32 timar, calar, stsr;

	cdns_rtc_alarm_irq_enable(dev, 0);

	timar = cdns_rtc_time2reg(&alarm->time);
	calar = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(alarm->time.tm_mday))
	\| FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(alarm->time.tm_mon + 1));

	/* Update registers, check valid alarm flags */
	for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
	writel(timar, crtc->regs + CDNS_RTC_TIMAR);
	writel(calar, crtc->regs + CDNS_RTC_CALAR);
	stsr = readl(crtc->regs + CDNS_RTC_STSR);

	if ((stsr & CDNS_RTC_STSR_VTA_VCA) == CDNS_RTC_STSR_VTA_VCA) {
	ret = 0;
	break;
	}
	}

	if (!ret)
	cdns_rtc_alarm_irq_enable(dev, alarm->enabled);
	return ret;
	}

	static const struct rtc_class_ops cdns_rtc_ops = {
	.read_time = cdns_rtc_read_time,
	.set_time = cdns_rtc_set_time,
	.read_alarm = cdns_rtc_read_alarm,
	.set_alarm = cdns_rtc_set_alarm,
	.alarm_irq_enable = cdns_rtc_alarm_irq_enable,
	};

	static int cdns_rtc_probe(struct platform_device *pdev)
	{
	struct cdns_rtc *crtc;
	int ret;
	unsigned long ref_clk_freq;

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

	crtc->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(crtc->regs))
	return PTR_ERR(crtc->regs);

	crtc->irq = platform_get_irq(pdev, 0);
	if (crtc->irq < 0)
	return -EINVAL;

	crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
	if (IS_ERR(crtc->pclk)) {
	ret = PTR_ERR(crtc->pclk);
	dev_err(&pdev->dev,
	"Failed to retrieve the peripheral clock, %d\n", ret);
	return ret;
	}

	crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
	if (IS_ERR(crtc->ref_clk)) {
	ret = PTR_ERR(crtc->ref_clk);
	dev_err(&pdev->dev,
	"Failed to retrieve the reference clock, %d\n", ret);
	return ret;
	}

	crtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(crtc->rtc_dev))
	return PTR_ERR(crtc->rtc_dev);

	platform_set_drvdata(pdev, crtc);

	ret = clk_prepare_enable(crtc->pclk);
	if (ret) {
	dev_err(&pdev->dev,
	"Failed to enable the peripheral clock, %d\n", ret);
	return ret;
	}

	ret = clk_prepare_enable(crtc->ref_clk);
	if (ret) {
	dev_err(&pdev->dev,
	"Failed to enable the reference clock, %d\n", ret);
	goto err_disable_pclk;
	}

	ref_clk_freq = clk_get_rate(crtc->ref_clk);
	if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
	dev_err(&pdev->dev,
	"Invalid reference clock frequency %lu Hz.\n",
	ref_clk_freq);
	ret = -EINVAL;
	goto err_disable_ref_clk;
	}

	ret = devm_request_irq(&pdev->dev, crtc->irq,
	cdns_rtc_irq_handler, 0,
	dev_name(&pdev->dev), &pdev->dev);
	if (ret) {
	dev_err(&pdev->dev,
	"Failed to request interrupt for the device, %d\n",
	ret);
	goto err_disable_ref_clk;
	}

	/* The RTC supports 01.01.1900 - 31.12.2999 */
	crtc->rtc_dev->range_min = mktime64(1900, 1, 1, 0, 0, 0);
	crtc->rtc_dev->range_max = mktime64(2999, 12, 31, 23, 59, 59);

	crtc->rtc_dev->ops = &cdns_rtc_ops;
	device_init_wakeup(&pdev->dev, true);

	/* Always use 24-hour mode and keep the RTC values */
	writel(0, crtc->regs + CDNS_RTC_HMR);
	writel(CDNS_RTC_KRTCR_KRTC, crtc->regs + CDNS_RTC_KRTCR);

	ret = devm_rtc_register_device(crtc->rtc_dev);
	if (ret)
	goto err_disable_wakeup;

	return 0;

	err_disable_wakeup:
	device_init_wakeup(&pdev->dev, false);

	err_disable_ref_clk:
	clk_disable_unprepare(crtc->ref_clk);

	err_disable_pclk:
	clk_disable_unprepare(crtc->pclk);

	return ret;
	}

	static void cdns_rtc_remove(struct platform_device *pdev)
	{
	struct cdns_rtc *crtc = platform_get_drvdata(pdev);

	cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
	device_init_wakeup(&pdev->dev, 0);

	clk_disable_unprepare(crtc->pclk);
	clk_disable_unprepare(crtc->ref_clk);
	}

	#ifdef CONFIG_PM_SLEEP
	static int cdns_rtc_suspend(struct device *dev)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
	enable_irq_wake(crtc->irq);

	return 0;
	}

	static int cdns_rtc_resume(struct device *dev)
	{
	struct cdns_rtc *crtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
	disable_irq_wake(crtc->irq);

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);

	static const struct of_device_id cdns_rtc_of_match[] = {
	{ .compatible = "cdns,rtc-r109v3" },
	{ },
	};
	MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);

	static struct platform_driver cdns_rtc_driver = {
	.driver = {
	.name = "cdns-rtc",
	.of_match_table = cdns_rtc_of_match,
	.pm = &cdns_rtc_pm_ops,
	},
	.probe = cdns_rtc_probe,
	.remove = cdns_rtc_remove,
	};
	module_platform_driver(cdns_rtc_driver);

	MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
	MODULE_DESCRIPTION("Cadence RTC driver");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:cdns-rtc");