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

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * An RTC driver for Allwinner A10/A20
  *
  * Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.com>
  */

 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
 #include <linux/types.h>

 #define SUNXI_LOSC_CTRL				0x0000
 #define SUNXI_LOSC_CTRL_RTC_HMS_ACC		BIT(8)
 #define SUNXI_LOSC_CTRL_RTC_YMD_ACC		BIT(7)

 #define SUNXI_RTC_YMD				0x0004

 #define SUNXI_RTC_HMS				0x0008

 #define SUNXI_ALRM_DHMS				0x000c

 #define SUNXI_ALRM_EN				0x0014
 #define SUNXI_ALRM_EN_CNT_EN			BIT(8)

 #define SUNXI_ALRM_IRQ_EN			0x0018
 #define SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN		BIT(0)

 #define SUNXI_ALRM_IRQ_STA			0x001c
 #define SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND		BIT(0)

 #define SUNXI_MASK_DH				0x0000001f
 #define SUNXI_MASK_SM				0x0000003f
 #define SUNXI_MASK_M				0x0000000f
 #define SUNXI_MASK_LY				0x00000001
 #define SUNXI_MASK_D				0x00000ffe
 #define SUNXI_MASK_M				0x0000000f

 #define SUNXI_GET(x, mask, shift)		(((x) & ((mask) << (shift))) \
 							>> (shift))

 #define SUNXI_SET(x, mask, shift)		(((x) & (mask)) << (shift))

 /*
  * Get date values
  */
 #define SUNXI_DATE_GET_DAY_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 0)
 #define SUNXI_DATE_GET_MON_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_M, 8)
 #define SUNXI_DATE_GET_YEAR_VALUE(x, mask)	SUNXI_GET(x, mask, 16)

 /*
  * Get time values
  */
 #define SUNXI_TIME_GET_SEC_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 0)
 #define SUNXI_TIME_GET_MIN_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 8)
 #define SUNXI_TIME_GET_HOUR_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 16)

 /*
  * Get alarm values
  */
 #define SUNXI_ALRM_GET_SEC_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 0)
 #define SUNXI_ALRM_GET_MIN_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_SM, 8)
 #define SUNXI_ALRM_GET_HOUR_VALUE(x)		SUNXI_GET(x, SUNXI_MASK_DH, 16)

 /*
  * Set date values
  */
 #define SUNXI_DATE_SET_DAY_VALUE(x)		SUNXI_DATE_GET_DAY_VALUE(x)
 #define SUNXI_DATE_SET_MON_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_M, 8)
 #define SUNXI_DATE_SET_YEAR_VALUE(x, mask)	SUNXI_SET(x, mask, 16)
 #define SUNXI_LEAP_SET_VALUE(x, shift)		SUNXI_SET(x, SUNXI_MASK_LY, shift)

 /*
  * Set time values
  */
 #define SUNXI_TIME_SET_SEC_VALUE(x)		SUNXI_TIME_GET_SEC_VALUE(x)
 #define SUNXI_TIME_SET_MIN_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_SM, 8)
 #define SUNXI_TIME_SET_HOUR_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_DH, 16)

 /*
  * Set alarm values
  */
 #define SUNXI_ALRM_SET_SEC_VALUE(x)		SUNXI_ALRM_GET_SEC_VALUE(x)
 #define SUNXI_ALRM_SET_MIN_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_SM, 8)
 #define SUNXI_ALRM_SET_HOUR_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_DH, 16)
 #define SUNXI_ALRM_SET_DAY_VALUE(x)		SUNXI_SET(x, SUNXI_MASK_D, 21)

 /*
  * Time unit conversions
  */
 #define SEC_IN_MIN				60
 #define SEC_IN_HOUR				(60 * SEC_IN_MIN)
 #define SEC_IN_DAY				(24 * SEC_IN_HOUR)

 /*
  * The year parameter passed to the driver is usually an offset relative to
  * the year 1900. This macro is used to convert this offset to another one
  * relative to the minimum year allowed by the hardware.
  */
 #define SUNXI_YEAR_OFF(x)			((x)->min - 1900)

 /*
  * min and max year are arbitrary set considering the limited range of the
  * hardware register field
  */
 struct sunxi_rtc_data_year {
 	unsigned int min;		/* min year allowed */
 	unsigned int max;		/* max year allowed */
 	unsigned int mask;		/* mask for the year field */
 	unsigned char leap_shift;	/* bit shift to get the leap year */
 };

 static const struct sunxi_rtc_data_year data_year_param[] = {
 	[0] = {
 		.min		= 2010,
 		.max		= 2073,
 		.mask		= 0x3f,
 		.leap_shift	= 22,
 	},
 	[1] = {
 		.min		= 1970,
 		.max		= 2225,
 		.mask		= 0xff,
 		.leap_shift	= 24,
 	},
 };

 struct sunxi_rtc_dev {
 	struct rtc_device *rtc;
 	struct device *dev;
 	const struct sunxi_rtc_data_year *data_year;
 	void __iomem *base;
 	int irq;
 };

 static irqreturn_t sunxi_rtc_alarmirq(int irq, void *id)
 {
 	struct sunxi_rtc_dev *chip = (struct sunxi_rtc_dev *) id;
 	u32 val;

 	val = readl(chip->base + SUNXI_ALRM_IRQ_STA);

 	if (val & SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND) {
 		val |= SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND;
 		writel(val, chip->base + SUNXI_ALRM_IRQ_STA);

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

 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static void sunxi_rtc_setaie(unsigned int to, struct sunxi_rtc_dev *chip)
 {
 	u32 alrm_val = 0;
 	u32 alrm_irq_val = 0;

 	if (to) {
 		alrm_val = readl(chip->base + SUNXI_ALRM_EN);
 		alrm_val |= SUNXI_ALRM_EN_CNT_EN;

 		alrm_irq_val = readl(chip->base + SUNXI_ALRM_IRQ_EN);
 		alrm_irq_val |= SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN;
 	} else {
 		writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND,
 				chip->base + SUNXI_ALRM_IRQ_STA);
 	}

 	writel(alrm_val, chip->base + SUNXI_ALRM_EN);
 	writel(alrm_irq_val, chip->base + SUNXI_ALRM_IRQ_EN);
 }

 static int sunxi_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 {
 	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
 	struct rtc_time *alrm_tm = &wkalrm->time;
 	u32 alrm;
 	u32 alrm_en;
 	u32 date;

 	alrm = readl(chip->base + SUNXI_ALRM_DHMS);
 	date = readl(chip->base + SUNXI_RTC_YMD);

 	alrm_tm->tm_sec = SUNXI_ALRM_GET_SEC_VALUE(alrm);
 	alrm_tm->tm_min = SUNXI_ALRM_GET_MIN_VALUE(alrm);
 	alrm_tm->tm_hour = SUNXI_ALRM_GET_HOUR_VALUE(alrm);

 	alrm_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
 	alrm_tm->tm_mon = SUNXI_DATE_GET_MON_VALUE(date);
 	alrm_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
 			chip->data_year->mask);

 	alrm_tm->tm_mon -= 1;

 	/*
 	 * switch from (data_year->min)-relative offset to
 	 * a (1900)-relative one
 	 */
 	alrm_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);

 	alrm_en = readl(chip->base + SUNXI_ALRM_IRQ_EN);
 	if (alrm_en & SUNXI_ALRM_EN_CNT_EN)
 		wkalrm->enabled = 1;

 	return 0;
 }

 static int sunxi_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
 {
 	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
 	u32 date, time;

 	/*
 	 * read again in case it changes
 	 */
 	do {
 		date = readl(chip->base + SUNXI_RTC_YMD);
 		time = readl(chip->base + SUNXI_RTC_HMS);
 	} while ((date != readl(chip->base + SUNXI_RTC_YMD)) ||
 		 (time != readl(chip->base + SUNXI_RTC_HMS)));

 	rtc_tm->tm_sec  = SUNXI_TIME_GET_SEC_VALUE(time);
 	rtc_tm->tm_min  = SUNXI_TIME_GET_MIN_VALUE(time);
 	rtc_tm->tm_hour = SUNXI_TIME_GET_HOUR_VALUE(time);

 	rtc_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
 	rtc_tm->tm_mon  = SUNXI_DATE_GET_MON_VALUE(date);
 	rtc_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
 					chip->data_year->mask);

 	rtc_tm->tm_mon  -= 1;

 	/*
 	 * switch from (data_year->min)-relative offset to
 	 * a (1900)-relative one
 	 */
 	rtc_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);

 	return 0;
 }

 static int sunxi_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 {
 	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
 	struct rtc_time *alrm_tm = &wkalrm->time;
 	struct rtc_time tm_now;
 	u32 alrm;
 	time64_t diff;
 	unsigned long time_gap;
 	unsigned long time_gap_day;
 	unsigned long time_gap_hour;
 	unsigned long time_gap_min;
 	int ret;

 	ret = sunxi_rtc_gettime(dev, &tm_now);
 	if (ret < 0) {
 		dev_err(dev, "Error in getting time\n");
 		return -EINVAL;
 	}

 	diff = rtc_tm_sub(alrm_tm, &tm_now);
 	if (diff <= 0) {
 		dev_err(dev, "Date to set in the past\n");
 		return -EINVAL;
 	}

 	if (diff > 255 * SEC_IN_DAY) {
 		dev_err(dev, "Day must be in the range 0 - 255\n");
 		return -EINVAL;
 	}

 	time_gap = diff;
 	time_gap_day = time_gap / SEC_IN_DAY;
 	time_gap -= time_gap_day * SEC_IN_DAY;
 	time_gap_hour = time_gap / SEC_IN_HOUR;
 	time_gap -= time_gap_hour * SEC_IN_HOUR;
 	time_gap_min = time_gap / SEC_IN_MIN;
 	time_gap -= time_gap_min * SEC_IN_MIN;

 	sunxi_rtc_setaie(0, chip);
 	writel(0, chip->base + SUNXI_ALRM_DHMS);
 	usleep_range(100, 300);

 	alrm = SUNXI_ALRM_SET_SEC_VALUE(time_gap) |
 		SUNXI_ALRM_SET_MIN_VALUE(time_gap_min) |
 		SUNXI_ALRM_SET_HOUR_VALUE(time_gap_hour) |
 		SUNXI_ALRM_SET_DAY_VALUE(time_gap_day);
 	writel(alrm, chip->base + SUNXI_ALRM_DHMS);

 	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);
 	writel(SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN, chip->base + SUNXI_ALRM_IRQ_EN);

 	sunxi_rtc_setaie(wkalrm->enabled, chip);

 	return 0;
 }

 static int sunxi_rtc_wait(struct sunxi_rtc_dev *chip, int offset,
 			  unsigned int mask, unsigned int ms_timeout)
 {
 	const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);
 	u32 reg;

 	do {
 		reg = readl(chip->base + offset);
 		reg &= mask;

 		if (reg == mask)
 			return 0;

 	} while (time_before(jiffies, timeout));

 	return -ETIMEDOUT;
 }

 static int sunxi_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
 {
 	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
 	u32 date = 0;
 	u32 time = 0;
 	unsigned int year;

 	/*
 	 * the input rtc_tm->tm_year is the offset relative to 1900. We use
 	 * the SUNXI_YEAR_OFF macro to rebase it with respect to the min year
 	 * allowed by the hardware
 	 */

 	year = rtc_tm->tm_year + 1900;
 	if (year < chip->data_year->min || year > chip->data_year->max) {
 		dev_err(dev, "rtc only supports year in range %u - %u\n",
 			chip->data_year->min, chip->data_year->max);
 		return -EINVAL;
 	}

 	rtc_tm->tm_year -= SUNXI_YEAR_OFF(chip->data_year);
 	rtc_tm->tm_mon += 1;

 	date = SUNXI_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |
 		SUNXI_DATE_SET_MON_VALUE(rtc_tm->tm_mon)  |
 		SUNXI_DATE_SET_YEAR_VALUE(rtc_tm->tm_year,
 				chip->data_year->mask);

 	if (is_leap_year(year))
 		date |= SUNXI_LEAP_SET_VALUE(1, chip->data_year->leap_shift);

 	time = SUNXI_TIME_SET_SEC_VALUE(rtc_tm->tm_sec)  |
 		SUNXI_TIME_SET_MIN_VALUE(rtc_tm->tm_min)  |
 		SUNXI_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);

 	writel(0, chip->base + SUNXI_RTC_HMS);
 	writel(0, chip->base + SUNXI_RTC_YMD);

 	writel(time, chip->base + SUNXI_RTC_HMS);

 	/*
 	 * After writing the RTC HH-MM-SS register, the
 	 * SUNXI_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not
 	 * be cleared until the real writing operation is finished
 	 */

 	if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
 				SUNXI_LOSC_CTRL_RTC_HMS_ACC, 50)) {
 		dev_err(dev, "Failed to set rtc time.\n");
 		return -1;
 	}

 	writel(date, chip->base + SUNXI_RTC_YMD);

 	/*
 	 * After writing the RTC YY-MM-DD register, the
 	 * SUNXI_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not
 	 * be cleared until the real writing operation is finished
 	 */

 	if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
 				SUNXI_LOSC_CTRL_RTC_YMD_ACC, 50)) {
 		dev_err(dev, "Failed to set rtc time.\n");
 		return -1;
 	}

 	return 0;
 }

 static int sunxi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);

 	if (!enabled)
 		sunxi_rtc_setaie(enabled, chip);

 	return 0;
 }

 static const struct rtc_class_ops sunxi_rtc_ops = {
 	.read_time		= sunxi_rtc_gettime,
 	.set_time		= sunxi_rtc_settime,
 	.read_alarm		= sunxi_rtc_getalarm,
 	.set_alarm		= sunxi_rtc_setalarm,
 	.alarm_irq_enable	= sunxi_rtc_alarm_irq_enable
 };

 static const struct of_device_id sunxi_rtc_dt_ids[] = {
 	{ .compatible = "allwinner,sun4i-a10-rtc", .data = &data_year_param[0] },
 	{ .compatible = "allwinner,sun7i-a20-rtc", .data = &data_year_param[1] },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, sunxi_rtc_dt_ids);

 static int sunxi_rtc_probe(struct platform_device *pdev)
 {
 	struct sunxi_rtc_dev *chip;
 	int ret;

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

 	platform_set_drvdata(pdev, chip);
 	chip->dev = &pdev->dev;

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

 	chip->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(chip->base))
 		return PTR_ERR(chip->base);

 	chip->irq = platform_get_irq(pdev, 0);
 	if (chip->irq < 0)
 		return chip->irq;
 	ret = devm_request_irq(&pdev->dev, chip->irq, sunxi_rtc_alarmirq,
 			0, dev_name(&pdev->dev), chip);
 	if (ret) {
 		dev_err(&pdev->dev, "Could not request IRQ\n");
 		return ret;
 	}

 	chip->data_year = of_device_get_match_data(&pdev->dev);
 	if (!chip->data_year) {
 		dev_err(&pdev->dev, "Unable to setup RTC data\n");
 		return -ENODEV;
 	}

 	/* clear the alarm count value */
 	writel(0, chip->base + SUNXI_ALRM_DHMS);

 	/* disable alarm, not generate irq pending */
 	writel(0, chip->base + SUNXI_ALRM_EN);

 	/* disable alarm week/cnt irq, unset to cpu */
 	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);

 	/* clear alarm week/cnt irq pending */
 	writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND, chip->base +
 			SUNXI_ALRM_IRQ_STA);

 	chip->rtc->ops = &sunxi_rtc_ops;

 	return devm_rtc_register_device(chip->rtc);
 }

 static struct platform_driver sunxi_rtc_driver = {
 	.probe		= sunxi_rtc_probe,
 	.driver		= {
 		.name		= "sunxi-rtc",
 		.of_match_table = sunxi_rtc_dt_ids,
 	},
 };

 module_platform_driver(sunxi_rtc_driver);

 MODULE_DESCRIPTION("sunxi RTC driver");
 MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* An RTC driver for Allwinner A10/A20
	*
	* Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.com>
	*/

	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/fs.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/rtc.h>
	#include <linux/types.h>

	#define SUNXI_LOSC_CTRL 0x0000
	#define SUNXI_LOSC_CTRL_RTC_HMS_ACC BIT(8)
	#define SUNXI_LOSC_CTRL_RTC_YMD_ACC BIT(7)

	#define SUNXI_RTC_YMD 0x0004

	#define SUNXI_RTC_HMS 0x0008

	#define SUNXI_ALRM_DHMS 0x000c

	#define SUNXI_ALRM_EN 0x0014
	#define SUNXI_ALRM_EN_CNT_EN BIT(8)

	#define SUNXI_ALRM_IRQ_EN 0x0018
	#define SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN BIT(0)

	#define SUNXI_ALRM_IRQ_STA 0x001c
	#define SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND BIT(0)

	#define SUNXI_MASK_DH 0x0000001f
	#define SUNXI_MASK_SM 0x0000003f
	#define SUNXI_MASK_M 0x0000000f
	#define SUNXI_MASK_LY 0x00000001
	#define SUNXI_MASK_D 0x00000ffe
	#define SUNXI_MASK_M 0x0000000f

	#define SUNXI_GET(x, mask, shift) (((x) & ((mask) << (shift))) \
	>> (shift))

	#define SUNXI_SET(x, mask, shift) (((x) & (mask)) << (shift))

	/*
	* Get date values
	*/
	#define SUNXI_DATE_GET_DAY_VALUE(x) SUNXI_GET(x, SUNXI_MASK_DH, 0)
	#define SUNXI_DATE_GET_MON_VALUE(x) SUNXI_GET(x, SUNXI_MASK_M, 8)
	#define SUNXI_DATE_GET_YEAR_VALUE(x, mask) SUNXI_GET(x, mask, 16)

	/*
	* Get time values
	*/
	#define SUNXI_TIME_GET_SEC_VALUE(x) SUNXI_GET(x, SUNXI_MASK_SM, 0)
	#define SUNXI_TIME_GET_MIN_VALUE(x) SUNXI_GET(x, SUNXI_MASK_SM, 8)
	#define SUNXI_TIME_GET_HOUR_VALUE(x) SUNXI_GET(x, SUNXI_MASK_DH, 16)

	/*
	* Get alarm values
	*/
	#define SUNXI_ALRM_GET_SEC_VALUE(x) SUNXI_GET(x, SUNXI_MASK_SM, 0)
	#define SUNXI_ALRM_GET_MIN_VALUE(x) SUNXI_GET(x, SUNXI_MASK_SM, 8)
	#define SUNXI_ALRM_GET_HOUR_VALUE(x) SUNXI_GET(x, SUNXI_MASK_DH, 16)

	/*
	* Set date values
	*/
	#define SUNXI_DATE_SET_DAY_VALUE(x) SUNXI_DATE_GET_DAY_VALUE(x)
	#define SUNXI_DATE_SET_MON_VALUE(x) SUNXI_SET(x, SUNXI_MASK_M, 8)
	#define SUNXI_DATE_SET_YEAR_VALUE(x, mask) SUNXI_SET(x, mask, 16)
	#define SUNXI_LEAP_SET_VALUE(x, shift) SUNXI_SET(x, SUNXI_MASK_LY, shift)

	/*
	* Set time values
	*/
	#define SUNXI_TIME_SET_SEC_VALUE(x) SUNXI_TIME_GET_SEC_VALUE(x)
	#define SUNXI_TIME_SET_MIN_VALUE(x) SUNXI_SET(x, SUNXI_MASK_SM, 8)
	#define SUNXI_TIME_SET_HOUR_VALUE(x) SUNXI_SET(x, SUNXI_MASK_DH, 16)

	/*
	* Set alarm values
	*/
	#define SUNXI_ALRM_SET_SEC_VALUE(x) SUNXI_ALRM_GET_SEC_VALUE(x)
	#define SUNXI_ALRM_SET_MIN_VALUE(x) SUNXI_SET(x, SUNXI_MASK_SM, 8)
	#define SUNXI_ALRM_SET_HOUR_VALUE(x) SUNXI_SET(x, SUNXI_MASK_DH, 16)
	#define SUNXI_ALRM_SET_DAY_VALUE(x) SUNXI_SET(x, SUNXI_MASK_D, 21)

	/*
	* Time unit conversions
	*/
	#define SEC_IN_MIN 60
	#define SEC_IN_HOUR (60 * SEC_IN_MIN)
	#define SEC_IN_DAY (24 * SEC_IN_HOUR)

	/*
	* The year parameter passed to the driver is usually an offset relative to
	* the year 1900. This macro is used to convert this offset to another one
	* relative to the minimum year allowed by the hardware.
	*/
	#define SUNXI_YEAR_OFF(x) ((x)->min - 1900)

	/*
	* min and max year are arbitrary set considering the limited range of the
	* hardware register field
	*/
	struct sunxi_rtc_data_year {
	unsigned int min; /* min year allowed */
	unsigned int max; /* max year allowed */
	unsigned int mask; /* mask for the year field */
	unsigned char leap_shift; /* bit shift to get the leap year */
	};

	static const struct sunxi_rtc_data_year data_year_param[] = {
	[0] = {
	.min = 2010,
	.max = 2073,
	.mask = 0x3f,
	.leap_shift = 22,
	},
	[1] = {
	.min = 1970,
	.max = 2225,
	.mask = 0xff,
	.leap_shift = 24,
	},
	};

	struct sunxi_rtc_dev {
	struct rtc_device *rtc;
	struct device *dev;
	const struct sunxi_rtc_data_year *data_year;
	void __iomem *base;
	int irq;
	};

	static irqreturn_t sunxi_rtc_alarmirq(int irq, void *id)
	{
	struct sunxi_rtc_dev chip = (struct sunxi_rtc_dev ) id;
	u32 val;

	val = readl(chip->base + SUNXI_ALRM_IRQ_STA);

	if (val & SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND) {
	val \|= SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND;
	writel(val, chip->base + SUNXI_ALRM_IRQ_STA);

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

	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static void sunxi_rtc_setaie(unsigned int to, struct sunxi_rtc_dev *chip)
	{
	u32 alrm_val = 0;
	u32 alrm_irq_val = 0;

	if (to) {
	alrm_val = readl(chip->base + SUNXI_ALRM_EN);
	alrm_val \|= SUNXI_ALRM_EN_CNT_EN;

	alrm_irq_val = readl(chip->base + SUNXI_ALRM_IRQ_EN);
	alrm_irq_val \|= SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN;
	} else {
	writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND,
	chip->base + SUNXI_ALRM_IRQ_STA);
	}

	writel(alrm_val, chip->base + SUNXI_ALRM_EN);
	writel(alrm_irq_val, chip->base + SUNXI_ALRM_IRQ_EN);
	}

	static int sunxi_rtc_getalarm(struct device dev, struct rtc_wkalrm wkalrm)
	{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	struct rtc_time *alrm_tm = &wkalrm->time;
	u32 alrm;
	u32 alrm_en;
	u32 date;

	alrm = readl(chip->base + SUNXI_ALRM_DHMS);
	date = readl(chip->base + SUNXI_RTC_YMD);

	alrm_tm->tm_sec = SUNXI_ALRM_GET_SEC_VALUE(alrm);
	alrm_tm->tm_min = SUNXI_ALRM_GET_MIN_VALUE(alrm);
	alrm_tm->tm_hour = SUNXI_ALRM_GET_HOUR_VALUE(alrm);

	alrm_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
	alrm_tm->tm_mon = SUNXI_DATE_GET_MON_VALUE(date);
	alrm_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
	chip->data_year->mask);

	alrm_tm->tm_mon -= 1;

	/*
	* switch from (data_year->min)-relative offset to
	* a (1900)-relative one
	*/
	alrm_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);

	alrm_en = readl(chip->base + SUNXI_ALRM_IRQ_EN);
	if (alrm_en & SUNXI_ALRM_EN_CNT_EN)
	wkalrm->enabled = 1;

	return 0;
	}

	static int sunxi_rtc_gettime(struct device dev, struct rtc_time rtc_tm)
	{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	u32 date, time;

	/*
	* read again in case it changes
	*/
	do {
	date = readl(chip->base + SUNXI_RTC_YMD);
	time = readl(chip->base + SUNXI_RTC_HMS);
	} while ((date != readl(chip->base + SUNXI_RTC_YMD)) \|\|
	(time != readl(chip->base + SUNXI_RTC_HMS)));

	rtc_tm->tm_sec = SUNXI_TIME_GET_SEC_VALUE(time);
	rtc_tm->tm_min = SUNXI_TIME_GET_MIN_VALUE(time);
	rtc_tm->tm_hour = SUNXI_TIME_GET_HOUR_VALUE(time);

	rtc_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
	rtc_tm->tm_mon = SUNXI_DATE_GET_MON_VALUE(date);
	rtc_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
	chip->data_year->mask);

	rtc_tm->tm_mon -= 1;

	/*
	* switch from (data_year->min)-relative offset to
	* a (1900)-relative one
	*/
	rtc_tm->tm_year += SUNXI_YEAR_OFF(chip->data_year);

	return 0;
	}

	static int sunxi_rtc_setalarm(struct device dev, struct rtc_wkalrm wkalrm)
	{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	struct rtc_time *alrm_tm = &wkalrm->time;
	struct rtc_time tm_now;
	u32 alrm;
	time64_t diff;
	unsigned long time_gap;
	unsigned long time_gap_day;
	unsigned long time_gap_hour;
	unsigned long time_gap_min;
	int ret;

	ret = sunxi_rtc_gettime(dev, &tm_now);
	if (ret < 0) {
	dev_err(dev, "Error in getting time\n");
	return -EINVAL;
	}

	diff = rtc_tm_sub(alrm_tm, &tm_now);
	if (diff <= 0) {
	dev_err(dev, "Date to set in the past\n");
	return -EINVAL;
	}

	if (diff > 255 * SEC_IN_DAY) {
	dev_err(dev, "Day must be in the range 0 - 255\n");
	return -EINVAL;
	}

	time_gap = diff;
	time_gap_day = time_gap / SEC_IN_DAY;
	time_gap -= time_gap_day * SEC_IN_DAY;
	time_gap_hour = time_gap / SEC_IN_HOUR;
	time_gap -= time_gap_hour * SEC_IN_HOUR;
	time_gap_min = time_gap / SEC_IN_MIN;
	time_gap -= time_gap_min * SEC_IN_MIN;

	sunxi_rtc_setaie(0, chip);
	writel(0, chip->base + SUNXI_ALRM_DHMS);
	usleep_range(100, 300);

	alrm = SUNXI_ALRM_SET_SEC_VALUE(time_gap) \|
	SUNXI_ALRM_SET_MIN_VALUE(time_gap_min) \|
	SUNXI_ALRM_SET_HOUR_VALUE(time_gap_hour) \|
	SUNXI_ALRM_SET_DAY_VALUE(time_gap_day);
	writel(alrm, chip->base + SUNXI_ALRM_DHMS);

	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);
	writel(SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN, chip->base + SUNXI_ALRM_IRQ_EN);

	sunxi_rtc_setaie(wkalrm->enabled, chip);

	return 0;
	}

	static int sunxi_rtc_wait(struct sunxi_rtc_dev *chip, int offset,
	unsigned int mask, unsigned int ms_timeout)
	{
	const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);
	u32 reg;

	do {
	reg = readl(chip->base + offset);
	reg &= mask;

	if (reg == mask)
	return 0;

	} while (time_before(jiffies, timeout));

	return -ETIMEDOUT;
	}

	static int sunxi_rtc_settime(struct device dev, struct rtc_time rtc_tm)
	{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
	u32 date = 0;
	u32 time = 0;
	unsigned int year;

	/*
	* the input rtc_tm->tm_year is the offset relative to 1900. We use
	* the SUNXI_YEAR_OFF macro to rebase it with respect to the min year
	* allowed by the hardware
	*/

	year = rtc_tm->tm_year + 1900;
	if (year < chip->data_year->min \|\| year > chip->data_year->max) {
	dev_err(dev, "rtc only supports year in range %u - %u\n",
	chip->data_year->min, chip->data_year->max);
	return -EINVAL;
	}

	rtc_tm->tm_year -= SUNXI_YEAR_OFF(chip->data_year);
	rtc_tm->tm_mon += 1;

	date = SUNXI_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) \|
	SUNXI_DATE_SET_MON_VALUE(rtc_tm->tm_mon) \|
	SUNXI_DATE_SET_YEAR_VALUE(rtc_tm->tm_year,
	chip->data_year->mask);

	if (is_leap_year(year))
	date \|= SUNXI_LEAP_SET_VALUE(1, chip->data_year->leap_shift);

	time = SUNXI_TIME_SET_SEC_VALUE(rtc_tm->tm_sec) \|
	SUNXI_TIME_SET_MIN_VALUE(rtc_tm->tm_min) \|
	SUNXI_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);

	writel(0, chip->base + SUNXI_RTC_HMS);
	writel(0, chip->base + SUNXI_RTC_YMD);

	writel(time, chip->base + SUNXI_RTC_HMS);

	/*
	* After writing the RTC HH-MM-SS register, the
	* SUNXI_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not
	* be cleared until the real writing operation is finished
	*/

	if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
	SUNXI_LOSC_CTRL_RTC_HMS_ACC, 50)) {
	dev_err(dev, "Failed to set rtc time.\n");
	return -1;
	}

	writel(date, chip->base + SUNXI_RTC_YMD);

	/*
	* After writing the RTC YY-MM-DD register, the
	* SUNXI_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not
	* be cleared until the real writing operation is finished
	*/

	if (sunxi_rtc_wait(chip, SUNXI_LOSC_CTRL,
	SUNXI_LOSC_CTRL_RTC_YMD_ACC, 50)) {
	dev_err(dev, "Failed to set rtc time.\n");
	return -1;
	}

	return 0;
	}

	static int sunxi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);

	if (!enabled)
	sunxi_rtc_setaie(enabled, chip);

	return 0;
	}

	static const struct rtc_class_ops sunxi_rtc_ops = {
	.read_time = sunxi_rtc_gettime,
	.set_time = sunxi_rtc_settime,
	.read_alarm = sunxi_rtc_getalarm,
	.set_alarm = sunxi_rtc_setalarm,
	.alarm_irq_enable = sunxi_rtc_alarm_irq_enable
	};

	static const struct of_device_id sunxi_rtc_dt_ids[] = {
	{ .compatible = "allwinner,sun4i-a10-rtc", .data = &data_year_param[0] },
	{ .compatible = "allwinner,sun7i-a20-rtc", .data = &data_year_param[1] },
	{ /* sentinel */ },
	};
	MODULE_DEVICE_TABLE(of, sunxi_rtc_dt_ids);

	static int sunxi_rtc_probe(struct platform_device *pdev)
	{
	struct sunxi_rtc_dev *chip;
	int ret;

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

	platform_set_drvdata(pdev, chip);
	chip->dev = &pdev->dev;

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

	chip->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(chip->base))
	return PTR_ERR(chip->base);

	chip->irq = platform_get_irq(pdev, 0);
	if (chip->irq < 0)
	return chip->irq;
	ret = devm_request_irq(&pdev->dev, chip->irq, sunxi_rtc_alarmirq,
	0, dev_name(&pdev->dev), chip);
	if (ret) {
	dev_err(&pdev->dev, "Could not request IRQ\n");
	return ret;
	}

	chip->data_year = of_device_get_match_data(&pdev->dev);
	if (!chip->data_year) {
	dev_err(&pdev->dev, "Unable to setup RTC data\n");
	return -ENODEV;
	}

	/* clear the alarm count value */
	writel(0, chip->base + SUNXI_ALRM_DHMS);

	/* disable alarm, not generate irq pending */
	writel(0, chip->base + SUNXI_ALRM_EN);

	/* disable alarm week/cnt irq, unset to cpu */
	writel(0, chip->base + SUNXI_ALRM_IRQ_EN);

	/* clear alarm week/cnt irq pending */
	writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND, chip->base +
	SUNXI_ALRM_IRQ_STA);

	chip->rtc->ops = &sunxi_rtc_ops;

	return devm_rtc_register_device(chip->rtc);
	}

	static struct platform_driver sunxi_rtc_driver = {
	.probe = sunxi_rtc_probe,
	.driver = {
	.name = "sunxi-rtc",
	.of_match_table = sunxi_rtc_dt_ids,
	},
	};

	module_platform_driver(sunxi_rtc_driver);

	MODULE_DESCRIPTION("sunxi RTC driver");
	MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
	MODULE_LICENSE("GPL");