drivers/rtc/rtc-rzn1.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Renesas RZ/N1 Real Time Clock interface for Linux
  *
  * Copyright:
  * - 2014 Renesas Electronics Europe Limited
  * - 2022 Schneider Electric
  *
  * Authors:
  * - Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>
  * - Miquel Raynal <miquel.raynal@bootlin.com>
  */

 #include <linux/bcd.h>
 #include <linux/init.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/rtc.h>

 #define RZN1_RTC_CTL0 0x00
 #define   RZN1_RTC_CTL0_SLSB_SUBU 0
 #define   RZN1_RTC_CTL0_SLSB_SCMP BIT(4)
 #define   RZN1_RTC_CTL0_AMPM BIT(5)
 #define   RZN1_RTC_CTL0_CE BIT(7)

 #define RZN1_RTC_CTL1 0x04
 #define   RZN1_RTC_CTL1_ALME BIT(4)

 #define RZN1_RTC_CTL2 0x08
 #define   RZN1_RTC_CTL2_WAIT BIT(0)
 #define   RZN1_RTC_CTL2_WST BIT(1)
 #define   RZN1_RTC_CTL2_WUST BIT(5)
 #define   RZN1_RTC_CTL2_STOPPED (RZN1_RTC_CTL2_WAIT | RZN1_RTC_CTL2_WST)

 #define RZN1_RTC_SEC 0x14
 #define RZN1_RTC_MIN 0x18
 #define RZN1_RTC_HOUR 0x1c
 #define RZN1_RTC_WEEK 0x20
 #define RZN1_RTC_DAY 0x24
 #define RZN1_RTC_MONTH 0x28
 #define RZN1_RTC_YEAR 0x2c

 #define RZN1_RTC_SUBU 0x38
 #define   RZN1_RTC_SUBU_DEV BIT(7)
 #define   RZN1_RTC_SUBU_DECR BIT(6)

 #define RZN1_RTC_ALM 0x40
 #define RZN1_RTC_ALH 0x44
 #define RZN1_RTC_ALW 0x48

 #define RZN1_RTC_SECC 0x4c
 #define RZN1_RTC_MINC 0x50
 #define RZN1_RTC_HOURC 0x54
 #define RZN1_RTC_WEEKC 0x58
 #define RZN1_RTC_DAYC 0x5c
 #define RZN1_RTC_MONTHC 0x60
 #define RZN1_RTC_YEARC 0x64

 struct rzn1_rtc {
 	struct rtc_device *rtcdev;
 	void __iomem *base;
 };

 static void rzn1_rtc_get_time_snapshot(struct rzn1_rtc *rtc, struct rtc_time *tm)
 {
 	tm->tm_sec = readl(rtc->base + RZN1_RTC_SECC);
 	tm->tm_min = readl(rtc->base + RZN1_RTC_MINC);
 	tm->tm_hour = readl(rtc->base + RZN1_RTC_HOURC);
 	tm->tm_wday = readl(rtc->base + RZN1_RTC_WEEKC);
 	tm->tm_mday = readl(rtc->base + RZN1_RTC_DAYC);
 	tm->tm_mon = readl(rtc->base + RZN1_RTC_MONTHC);
 	tm->tm_year = readl(rtc->base + RZN1_RTC_YEARC);
 }

 static unsigned int rzn1_rtc_tm_to_wday(struct rtc_time *tm)
 {
 	time64_t time;
 	unsigned int days;
 	u32 secs;

 	time = rtc_tm_to_time64(tm);
 	days = div_s64_rem(time, 86400, &secs);

 	/* day of the week, 1970-01-01 was a Thursday */
 	return (days + 4) % 7;
 }

 static int rzn1_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	u32 val, secs;

 	/*
 	 * The RTC was not started or is stopped and thus does not carry the
 	 * proper time/date.
 	 */
 	val = readl(rtc->base + RZN1_RTC_CTL2);
 	if (val & RZN1_RTC_CTL2_STOPPED)
 		return -EINVAL;

 	rzn1_rtc_get_time_snapshot(rtc, tm);
 	secs = readl(rtc->base + RZN1_RTC_SECC);
 	if (tm->tm_sec != secs)
 		rzn1_rtc_get_time_snapshot(rtc, tm);

 	tm->tm_sec = bcd2bin(tm->tm_sec);
 	tm->tm_min = bcd2bin(tm->tm_min);
 	tm->tm_hour = bcd2bin(tm->tm_hour);
 	tm->tm_wday = bcd2bin(tm->tm_wday);
 	tm->tm_mday = bcd2bin(tm->tm_mday);
 	tm->tm_mon = bcd2bin(tm->tm_mon);
 	tm->tm_year = bcd2bin(tm->tm_year);

 	return 0;
 }

 static int rzn1_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	u32 val;
 	int ret;

 	tm->tm_sec = bin2bcd(tm->tm_sec);
 	tm->tm_min = bin2bcd(tm->tm_min);
 	tm->tm_hour = bin2bcd(tm->tm_hour);
 	tm->tm_wday = bin2bcd(rzn1_rtc_tm_to_wday(tm));
 	tm->tm_mday = bin2bcd(tm->tm_mday);
 	tm->tm_mon = bin2bcd(tm->tm_mon);
 	tm->tm_year = bin2bcd(tm->tm_year);

 	val = readl(rtc->base + RZN1_RTC_CTL2);
 	if (!(val & RZN1_RTC_CTL2_STOPPED)) {
 		/* Hold the counter if it was counting up */
 		writel(RZN1_RTC_CTL2_WAIT, rtc->base + RZN1_RTC_CTL2);

 		/* Wait for the counter to stop: two 32k clock cycles */
 		usleep_range(61, 100);
 		ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, val,
 					 val & RZN1_RTC_CTL2_WST, 0, 100);
 		if (ret)
 			return ret;
 	}

 	writel(tm->tm_sec, rtc->base + RZN1_RTC_SEC);
 	writel(tm->tm_min, rtc->base + RZN1_RTC_MIN);
 	writel(tm->tm_hour, rtc->base + RZN1_RTC_HOUR);
 	writel(tm->tm_wday, rtc->base + RZN1_RTC_WEEK);
 	writel(tm->tm_mday, rtc->base + RZN1_RTC_DAY);
 	writel(tm->tm_mon, rtc->base + RZN1_RTC_MONTH);
 	writel(tm->tm_year, rtc->base + RZN1_RTC_YEAR);
 	writel(0, rtc->base + RZN1_RTC_CTL2);

 	return 0;
 }

 static irqreturn_t rzn1_rtc_alarm_irq(int irq, void *dev_id)
 {
 	struct rzn1_rtc *rtc = dev_id;

 	rtc_update_irq(rtc->rtcdev, 1, RTC_AF | RTC_IRQF);

 	return IRQ_HANDLED;
 }

 static int rzn1_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	u32 ctl1 = readl(rtc->base + RZN1_RTC_CTL1);

 	if (enable)
 		ctl1 |= RZN1_RTC_CTL1_ALME;
 	else
 		ctl1 &= ~RZN1_RTC_CTL1_ALME;

 	writel(ctl1, rtc->base + RZN1_RTC_CTL1);

 	return 0;
 }

 static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &alrm->time;
 	unsigned int min, hour, wday, delta_days;
 	time64_t alarm;
 	u32 ctl1;
 	int ret;

 	ret = rzn1_rtc_read_time(dev, tm);
 	if (ret)
 		return ret;

 	min = readl(rtc->base + RZN1_RTC_ALM);
 	hour = readl(rtc->base + RZN1_RTC_ALH);
 	wday = readl(rtc->base + RZN1_RTC_ALW);

 	tm->tm_sec = 0;
 	tm->tm_min = bcd2bin(min);
 	tm->tm_hour = bcd2bin(hour);
 	delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
 	tm->tm_wday = fls(wday) - 1;

 	if (delta_days) {
 		alarm = rtc_tm_to_time64(tm) + (delta_days * 86400);
 		rtc_time64_to_tm(alarm, tm);
 	}

 	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
 	alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);

 	return 0;
 }

 static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &alrm->time, tm_now;
 	unsigned long alarm, farest;
 	unsigned int days_ahead, wday;
 	int ret;

 	ret = rzn1_rtc_read_time(dev, &tm_now);
 	if (ret)
 		return ret;

 	/* We cannot set alarms more than one week ahead */
 	farest = rtc_tm_to_time64(&tm_now) + (7 * 86400);
 	alarm = rtc_tm_to_time64(tm);
 	if (time_after(alarm, farest))
 		return -ERANGE;

 	/* Convert alarm day into week day */
 	days_ahead = tm->tm_mday - tm_now.tm_mday;
 	wday = (tm_now.tm_wday + days_ahead) % 7;

 	writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);
 	writel(bin2bcd(tm->tm_hour), rtc->base + RZN1_RTC_ALH);
 	writel(BIT(wday), rtc->base + RZN1_RTC_ALW);

 	rzn1_rtc_alarm_irq_enable(dev, alrm->enabled);

 	return 0;
 }

 static int rzn1_rtc_read_offset(struct device *dev, long *offset)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	unsigned int ppb_per_step;
 	bool subtract;
 	u32 val;

 	val = readl(rtc->base + RZN1_RTC_SUBU);
 	ppb_per_step = val & RZN1_RTC_SUBU_DEV ? 1017 : 3051;
 	subtract = val & RZN1_RTC_SUBU_DECR;
 	val &= 0x3F;

 	if (!val)
 		*offset = 0;
 	else if (subtract)
 		*offset = -(((~val) & 0x3F) + 1) * ppb_per_step;
 	else
 		*offset = (val - 1) * ppb_per_step;

 	return 0;
 }

 static int rzn1_rtc_set_offset(struct device *dev, long offset)
 {
 	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
 	int stepsh, stepsl, steps;
 	u32 subu = 0, ctl2;
 	int ret;

 	/*
 	 * Check which resolution mode (every 20 or 60s) can be used.
 	 * Between 2 and 124 clock pulses can be added or substracted.
 	 *
 	 * In 20s mode, the minimum resolution is 2 / (32768 * 20) which is
 	 * close to 3051 ppb. In 60s mode, the resolution is closer to 1017.
 	 */
 	stepsh = DIV_ROUND_CLOSEST(offset, 1017);
 	stepsl = DIV_ROUND_CLOSEST(offset, 3051);

 	if (stepsh >= -0x3E && stepsh <= 0x3E) {
 		/* 1017 ppb per step */
 		steps = stepsh;
 		subu |= RZN1_RTC_SUBU_DEV;
 	} else if (stepsl >= -0x3E && stepsl <= 0x3E) {
 		/* 3051 ppb per step */
 		steps = stepsl;
 	} else {
 		return -ERANGE;
 	}

 	if (!steps)
 		return 0;

 	if (steps > 0) {
 		subu |= steps + 1;
 	} else {
 		subu |= RZN1_RTC_SUBU_DECR;
 		subu |= (~(-steps - 1)) & 0x3F;
 	}

 	ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, ctl2,
 				 !(ctl2 & RZN1_RTC_CTL2_WUST), 100, 2000000);
 	if (ret)
 		return ret;

 	writel(subu, rtc->base + RZN1_RTC_SUBU);

 	return 0;
 }

 static const struct rtc_class_ops rzn1_rtc_ops = {
 	.read_time = rzn1_rtc_read_time,
 	.set_time = rzn1_rtc_set_time,
 	.read_alarm = rzn1_rtc_read_alarm,
 	.set_alarm = rzn1_rtc_set_alarm,
 	.alarm_irq_enable = rzn1_rtc_alarm_irq_enable,
 	.read_offset = rzn1_rtc_read_offset,
 	.set_offset = rzn1_rtc_set_offset,
 };

 static int rzn1_rtc_probe(struct platform_device *pdev)
 {
 	struct rzn1_rtc *rtc;
 	int alarm_irq;
 	int ret;

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

 	platform_set_drvdata(pdev, rtc);

 	rtc->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(rtc->base))
 		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->base), "Missing reg\n");

 	alarm_irq = platform_get_irq(pdev, 0);
 	if (alarm_irq < 0)
 		return alarm_irq;

 	rtc->rtcdev = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(rtc->rtcdev))
 		return PTR_ERR(rtc->rtcdev);

 	rtc->rtcdev->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	rtc->rtcdev->range_max = RTC_TIMESTAMP_END_2099;
 	rtc->rtcdev->ops = &rzn1_rtc_ops;
 	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtcdev->features);
 	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtcdev->features);

 	ret = devm_pm_runtime_enable(&pdev->dev);
 	if (ret < 0)
 		return ret;
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret < 0)
 		return ret;

 	/*
 	 * Ensure the clock counter is enabled.
 	 * Set 24-hour mode and possible oscillator offset compensation in SUBU mode.
 	 */
 	writel(RZN1_RTC_CTL0_CE | RZN1_RTC_CTL0_AMPM | RZN1_RTC_CTL0_SLSB_SUBU,
 	       rtc->base + RZN1_RTC_CTL0);

 	/* Disable all interrupts */
 	writel(0, rtc->base + RZN1_RTC_CTL1);

 	ret = devm_request_irq(&pdev->dev, alarm_irq, rzn1_rtc_alarm_irq, 0,
 			       dev_name(&pdev->dev), rtc);
 	if (ret) {
 		dev_err(&pdev->dev, "RTC timer interrupt not available\n");
 		goto dis_runtime_pm;
 	}

 	ret = devm_rtc_register_device(rtc->rtcdev);
 	if (ret)
 		goto dis_runtime_pm;

 	return 0;

 dis_runtime_pm:
 	pm_runtime_put(&pdev->dev);

 	return ret;
 }

 static void rzn1_rtc_remove(struct platform_device *pdev)
 {
 	pm_runtime_put(&pdev->dev);
 }

 static const struct of_device_id rzn1_rtc_of_match[] = {
 	{ .compatible	= "renesas,rzn1-rtc" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, rzn1_rtc_of_match);

 static struct platform_driver rzn1_rtc_driver = {
 	.probe = rzn1_rtc_probe,
 	.remove_new = rzn1_rtc_remove,
 	.driver = {
 		.name	= "rzn1-rtc",
 		.of_match_table = rzn1_rtc_of_match,
 	},
 };
 module_platform_driver(rzn1_rtc_driver);

 MODULE_AUTHOR("Michel Pollet <Michel.Pollet@bp.renesas.com");
 MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com");
 MODULE_DESCRIPTION("RZ/N1 RTC driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Renesas RZ/N1 Real Time Clock interface for Linux
	*
	* Copyright:
	* - 2014 Renesas Electronics Europe Limited
	* - 2022 Schneider Electric
	*
	* Authors:
	* - Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>
	* - Miquel Raynal <miquel.raynal@bootlin.com>
	*/

	#include <linux/bcd.h>
	#include <linux/init.h>
	#include <linux/iopoll.h>
	#include <linux/module.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/pm_runtime.h>
	#include <linux/rtc.h>

	#define RZN1_RTC_CTL0 0x00
	#define RZN1_RTC_CTL0_SLSB_SUBU 0
	#define RZN1_RTC_CTL0_SLSB_SCMP BIT(4)
	#define RZN1_RTC_CTL0_AMPM BIT(5)
	#define RZN1_RTC_CTL0_CE BIT(7)

	#define RZN1_RTC_CTL1 0x04
	#define RZN1_RTC_CTL1_ALME BIT(4)

	#define RZN1_RTC_CTL2 0x08
	#define RZN1_RTC_CTL2_WAIT BIT(0)
	#define RZN1_RTC_CTL2_WST BIT(1)
	#define RZN1_RTC_CTL2_WUST BIT(5)
	#define RZN1_RTC_CTL2_STOPPED (RZN1_RTC_CTL2_WAIT \| RZN1_RTC_CTL2_WST)

	#define RZN1_RTC_SEC 0x14
	#define RZN1_RTC_MIN 0x18
	#define RZN1_RTC_HOUR 0x1c
	#define RZN1_RTC_WEEK 0x20
	#define RZN1_RTC_DAY 0x24
	#define RZN1_RTC_MONTH 0x28
	#define RZN1_RTC_YEAR 0x2c

	#define RZN1_RTC_SUBU 0x38
	#define RZN1_RTC_SUBU_DEV BIT(7)
	#define RZN1_RTC_SUBU_DECR BIT(6)

	#define RZN1_RTC_ALM 0x40
	#define RZN1_RTC_ALH 0x44
	#define RZN1_RTC_ALW 0x48

	#define RZN1_RTC_SECC 0x4c
	#define RZN1_RTC_MINC 0x50
	#define RZN1_RTC_HOURC 0x54
	#define RZN1_RTC_WEEKC 0x58
	#define RZN1_RTC_DAYC 0x5c
	#define RZN1_RTC_MONTHC 0x60
	#define RZN1_RTC_YEARC 0x64

	struct rzn1_rtc {
	struct rtc_device *rtcdev;
	void __iomem *base;
	};

	static void rzn1_rtc_get_time_snapshot(struct rzn1_rtc rtc, struct rtc_time tm)
	{
	tm->tm_sec = readl(rtc->base + RZN1_RTC_SECC);
	tm->tm_min = readl(rtc->base + RZN1_RTC_MINC);
	tm->tm_hour = readl(rtc->base + RZN1_RTC_HOURC);
	tm->tm_wday = readl(rtc->base + RZN1_RTC_WEEKC);
	tm->tm_mday = readl(rtc->base + RZN1_RTC_DAYC);
	tm->tm_mon = readl(rtc->base + RZN1_RTC_MONTHC);
	tm->tm_year = readl(rtc->base + RZN1_RTC_YEARC);
	}

	static unsigned int rzn1_rtc_tm_to_wday(struct rtc_time *tm)
	{
	time64_t time;
	unsigned int days;
	u32 secs;

	time = rtc_tm_to_time64(tm);
	days = div_s64_rem(time, 86400, &secs);

	/* day of the week, 1970-01-01 was a Thursday */
	return (days + 4) % 7;
	}

	static int rzn1_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	u32 val, secs;

	/*
	* The RTC was not started or is stopped and thus does not carry the
	* proper time/date.
	*/
	val = readl(rtc->base + RZN1_RTC_CTL2);
	if (val & RZN1_RTC_CTL2_STOPPED)
	return -EINVAL;

	rzn1_rtc_get_time_snapshot(rtc, tm);
	secs = readl(rtc->base + RZN1_RTC_SECC);
	if (tm->tm_sec != secs)
	rzn1_rtc_get_time_snapshot(rtc, tm);

	tm->tm_sec = bcd2bin(tm->tm_sec);
	tm->tm_min = bcd2bin(tm->tm_min);
	tm->tm_hour = bcd2bin(tm->tm_hour);
	tm->tm_wday = bcd2bin(tm->tm_wday);
	tm->tm_mday = bcd2bin(tm->tm_mday);
	tm->tm_mon = bcd2bin(tm->tm_mon);
	tm->tm_year = bcd2bin(tm->tm_year);

	return 0;
	}

	static int rzn1_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	u32 val;
	int ret;

	tm->tm_sec = bin2bcd(tm->tm_sec);
	tm->tm_min = bin2bcd(tm->tm_min);
	tm->tm_hour = bin2bcd(tm->tm_hour);
	tm->tm_wday = bin2bcd(rzn1_rtc_tm_to_wday(tm));
	tm->tm_mday = bin2bcd(tm->tm_mday);
	tm->tm_mon = bin2bcd(tm->tm_mon);
	tm->tm_year = bin2bcd(tm->tm_year);

	val = readl(rtc->base + RZN1_RTC_CTL2);
	if (!(val & RZN1_RTC_CTL2_STOPPED)) {
	/* Hold the counter if it was counting up */
	writel(RZN1_RTC_CTL2_WAIT, rtc->base + RZN1_RTC_CTL2);

	/* Wait for the counter to stop: two 32k clock cycles */
	usleep_range(61, 100);
	ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, val,
	val & RZN1_RTC_CTL2_WST, 0, 100);
	if (ret)
	return ret;
	}

	writel(tm->tm_sec, rtc->base + RZN1_RTC_SEC);
	writel(tm->tm_min, rtc->base + RZN1_RTC_MIN);
	writel(tm->tm_hour, rtc->base + RZN1_RTC_HOUR);
	writel(tm->tm_wday, rtc->base + RZN1_RTC_WEEK);
	writel(tm->tm_mday, rtc->base + RZN1_RTC_DAY);
	writel(tm->tm_mon, rtc->base + RZN1_RTC_MONTH);
	writel(tm->tm_year, rtc->base + RZN1_RTC_YEAR);
	writel(0, rtc->base + RZN1_RTC_CTL2);

	return 0;
	}

	static irqreturn_t rzn1_rtc_alarm_irq(int irq, void *dev_id)
	{
	struct rzn1_rtc *rtc = dev_id;

	rtc_update_irq(rtc->rtcdev, 1, RTC_AF \| RTC_IRQF);

	return IRQ_HANDLED;
	}

	static int rzn1_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	u32 ctl1 = readl(rtc->base + RZN1_RTC_CTL1);

	if (enable)
	ctl1 \|= RZN1_RTC_CTL1_ALME;
	else
	ctl1 &= ~RZN1_RTC_CTL1_ALME;

	writel(ctl1, rtc->base + RZN1_RTC_CTL1);

	return 0;
	}

	static int rzn1_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time;
	unsigned int min, hour, wday, delta_days;
	time64_t alarm;
	u32 ctl1;
	int ret;

	ret = rzn1_rtc_read_time(dev, tm);
	if (ret)
	return ret;

	min = readl(rtc->base + RZN1_RTC_ALM);
	hour = readl(rtc->base + RZN1_RTC_ALH);
	wday = readl(rtc->base + RZN1_RTC_ALW);

	tm->tm_sec = 0;
	tm->tm_min = bcd2bin(min);
	tm->tm_hour = bcd2bin(hour);
	delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
	tm->tm_wday = fls(wday) - 1;

	if (delta_days) {
	alarm = rtc_tm_to_time64(tm) + (delta_days * 86400);
	rtc_time64_to_tm(alarm, tm);
	}

	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
	alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);

	return 0;
	}

	static int rzn1_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &alrm->time, tm_now;
	unsigned long alarm, farest;
	unsigned int days_ahead, wday;
	int ret;

	ret = rzn1_rtc_read_time(dev, &tm_now);
	if (ret)
	return ret;

	/* We cannot set alarms more than one week ahead */
	farest = rtc_tm_to_time64(&tm_now) + (7 * 86400);
	alarm = rtc_tm_to_time64(tm);
	if (time_after(alarm, farest))
	return -ERANGE;

	/* Convert alarm day into week day */
	days_ahead = tm->tm_mday - tm_now.tm_mday;
	wday = (tm_now.tm_wday + days_ahead) % 7;

	writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);
	writel(bin2bcd(tm->tm_hour), rtc->base + RZN1_RTC_ALH);
	writel(BIT(wday), rtc->base + RZN1_RTC_ALW);

	rzn1_rtc_alarm_irq_enable(dev, alrm->enabled);

	return 0;
	}

	static int rzn1_rtc_read_offset(struct device dev, long offset)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	unsigned int ppb_per_step;
	bool subtract;
	u32 val;

	val = readl(rtc->base + RZN1_RTC_SUBU);
	ppb_per_step = val & RZN1_RTC_SUBU_DEV ? 1017 : 3051;
	subtract = val & RZN1_RTC_SUBU_DECR;
	val &= 0x3F;

	if (!val)
	*offset = 0;
	else if (subtract)
	offset = -(((~val) & 0x3F) + 1) ppb_per_step;
	else
	offset = (val - 1) ppb_per_step;

	return 0;
	}

	static int rzn1_rtc_set_offset(struct device *dev, long offset)
	{
	struct rzn1_rtc *rtc = dev_get_drvdata(dev);
	int stepsh, stepsl, steps;
	u32 subu = 0, ctl2;
	int ret;

	/*
	* Check which resolution mode (every 20 or 60s) can be used.
	* Between 2 and 124 clock pulses can be added or substracted.
	*
	* In 20s mode, the minimum resolution is 2 / (32768 * 20) which is
	* close to 3051 ppb. In 60s mode, the resolution is closer to 1017.
	*/
	stepsh = DIV_ROUND_CLOSEST(offset, 1017);
	stepsl = DIV_ROUND_CLOSEST(offset, 3051);

	if (stepsh >= -0x3E && stepsh <= 0x3E) {
	/* 1017 ppb per step */
	steps = stepsh;
	subu \|= RZN1_RTC_SUBU_DEV;
	} else if (stepsl >= -0x3E && stepsl <= 0x3E) {
	/* 3051 ppb per step */
	steps = stepsl;
	} else {
	return -ERANGE;
	}

	if (!steps)
	return 0;

	if (steps > 0) {
	subu \|= steps + 1;
	} else {
	subu \|= RZN1_RTC_SUBU_DECR;
	subu \|= (~(-steps - 1)) & 0x3F;
	}

	ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, ctl2,
	!(ctl2 & RZN1_RTC_CTL2_WUST), 100, 2000000);
	if (ret)
	return ret;

	writel(subu, rtc->base + RZN1_RTC_SUBU);

	return 0;
	}

	static const struct rtc_class_ops rzn1_rtc_ops = {
	.read_time = rzn1_rtc_read_time,
	.set_time = rzn1_rtc_set_time,
	.read_alarm = rzn1_rtc_read_alarm,
	.set_alarm = rzn1_rtc_set_alarm,
	.alarm_irq_enable = rzn1_rtc_alarm_irq_enable,
	.read_offset = rzn1_rtc_read_offset,
	.set_offset = rzn1_rtc_set_offset,
	};

	static int rzn1_rtc_probe(struct platform_device *pdev)
	{
	struct rzn1_rtc *rtc;
	int alarm_irq;
	int ret;

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

	platform_set_drvdata(pdev, rtc);

	rtc->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(rtc->base))
	return dev_err_probe(&pdev->dev, PTR_ERR(rtc->base), "Missing reg\n");

	alarm_irq = platform_get_irq(pdev, 0);
	if (alarm_irq < 0)
	return alarm_irq;

	rtc->rtcdev = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(rtc->rtcdev))
	return PTR_ERR(rtc->rtcdev);

	rtc->rtcdev->range_min = RTC_TIMESTAMP_BEGIN_2000;
	rtc->rtcdev->range_max = RTC_TIMESTAMP_END_2099;
	rtc->rtcdev->ops = &rzn1_rtc_ops;
	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtcdev->features);
	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtcdev->features);

	ret = devm_pm_runtime_enable(&pdev->dev);
	if (ret < 0)
	return ret;
	ret = pm_runtime_resume_and_get(&pdev->dev);
	if (ret < 0)
	return ret;

	/*
	* Ensure the clock counter is enabled.
	* Set 24-hour mode and possible oscillator offset compensation in SUBU mode.
	*/
	writel(RZN1_RTC_CTL0_CE \| RZN1_RTC_CTL0_AMPM \| RZN1_RTC_CTL0_SLSB_SUBU,
	rtc->base + RZN1_RTC_CTL0);

	/* Disable all interrupts */
	writel(0, rtc->base + RZN1_RTC_CTL1);

	ret = devm_request_irq(&pdev->dev, alarm_irq, rzn1_rtc_alarm_irq, 0,
	dev_name(&pdev->dev), rtc);
	if (ret) {
	dev_err(&pdev->dev, "RTC timer interrupt not available\n");
	goto dis_runtime_pm;
	}

	ret = devm_rtc_register_device(rtc->rtcdev);
	if (ret)
	goto dis_runtime_pm;

	return 0;

	dis_runtime_pm:
	pm_runtime_put(&pdev->dev);

	return ret;
	}

	static void rzn1_rtc_remove(struct platform_device *pdev)
	{
	pm_runtime_put(&pdev->dev);
	}

	static const struct of_device_id rzn1_rtc_of_match[] = {
	{ .compatible = "renesas,rzn1-rtc" },
	{},
	};
	MODULE_DEVICE_TABLE(of, rzn1_rtc_of_match);

	static struct platform_driver rzn1_rtc_driver = {
	.probe = rzn1_rtc_probe,
	.remove_new = rzn1_rtc_remove,
	.driver = {
	.name = "rzn1-rtc",
	.of_match_table = rzn1_rtc_of_match,
	},
	};
	module_platform_driver(rzn1_rtc_driver);

	MODULE_AUTHOR("Michel Pollet <Michel.Pollet@bp.renesas.com");
	MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com");
	MODULE_DESCRIPTION("RZ/N1 RTC driver");
	MODULE_LICENSE("GPL");