drivers/rtc/rtc-r7301.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * EPSON TOYOCOM RTC-7301SF/DG Driver
  *
  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
  *
  * Based on rtc-rp5c01.c
  *
  * Datasheet: http://www5.epsondevice.com/en/products/parallel/rtc7301sf.html
  */

 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/delay.h>
 #include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>

 #define DRV_NAME "rtc-r7301"

 #define RTC7301_1_SEC		0x0	/* Bank 0 and Band 1 */
 #define RTC7301_10_SEC		0x1	/* Bank 0 and Band 1 */
 #define RTC7301_AE		BIT(3)
 #define RTC7301_1_MIN		0x2	/* Bank 0 and Band 1 */
 #define RTC7301_10_MIN		0x3	/* Bank 0 and Band 1 */
 #define RTC7301_1_HOUR		0x4	/* Bank 0 and Band 1 */
 #define RTC7301_10_HOUR		0x5	/* Bank 0 and Band 1 */
 #define RTC7301_DAY_OF_WEEK	0x6	/* Bank 0 and Band 1 */
 #define RTC7301_1_DAY		0x7	/* Bank 0 and Band 1 */
 #define RTC7301_10_DAY		0x8	/* Bank 0 and Band 1 */
 #define RTC7301_1_MONTH		0x9	/* Bank 0 */
 #define RTC7301_10_MONTH	0xa	/* Bank 0 */
 #define RTC7301_1_YEAR		0xb	/* Bank 0 */
 #define RTC7301_10_YEAR		0xc	/* Bank 0 */
 #define RTC7301_100_YEAR	0xd	/* Bank 0 */
 #define RTC7301_1000_YEAR	0xe	/* Bank 0 */
 #define RTC7301_ALARM_CONTROL	0xe	/* Bank 1 */
 #define RTC7301_ALARM_CONTROL_AIE	BIT(0)
 #define RTC7301_ALARM_CONTROL_AF	BIT(1)
 #define RTC7301_TIMER_CONTROL	0xe	/* Bank 2 */
 #define RTC7301_TIMER_CONTROL_TIE	BIT(0)
 #define RTC7301_TIMER_CONTROL_TF	BIT(1)
 #define RTC7301_CONTROL		0xf	/* All banks */
 #define RTC7301_CONTROL_BUSY		BIT(0)
 #define RTC7301_CONTROL_STOP		BIT(1)
 #define RTC7301_CONTROL_BANK_SEL_0	BIT(2)
 #define RTC7301_CONTROL_BANK_SEL_1	BIT(3)

 struct rtc7301_priv {
 	struct regmap *regmap;
 	int irq;
 	spinlock_t lock;
 	u8 bank;
 };

 /*
  * When the device is memory-mapped, some platforms pack the registers into
  * 32-bit access using the lower 8 bits at each 4-byte stride, while others
  * expose them as simply consecutive bytes.
  */
 static const struct regmap_config rtc7301_regmap_32_config = {
 	.reg_bits = 32,
 	.val_bits = 8,
 	.reg_stride = 4,
 };

 static const struct regmap_config rtc7301_regmap_8_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.reg_stride = 1,
 };

 static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
 {
 	int reg_stride = regmap_get_reg_stride(priv->regmap);
 	unsigned int val;

 	regmap_read(priv->regmap, reg_stride * reg, &val);

 	return val & 0xf;
 }

 static void rtc7301_write(struct rtc7301_priv *priv, u8 val, unsigned int reg)
 {
 	int reg_stride = regmap_get_reg_stride(priv->regmap);

 	regmap_write(priv->regmap, reg_stride * reg, val);
 }

 static void rtc7301_update_bits(struct rtc7301_priv *priv, unsigned int reg,
 				u8 mask, u8 val)
 {
 	int reg_stride = regmap_get_reg_stride(priv->regmap);

 	regmap_update_bits(priv->regmap, reg_stride * reg, mask, val);
 }

 static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
 {
 	int retries = 100;

 	while (retries-- > 0) {
 		u8 val;

 		val = rtc7301_read(priv, RTC7301_CONTROL);
 		if (!(val & RTC7301_CONTROL_BUSY))
 			return 0;

 		udelay(300);
 	}

 	return -ETIMEDOUT;
 }

 static void rtc7301_stop(struct rtc7301_priv *priv)
 {
 	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP,
 			    RTC7301_CONTROL_STOP);
 }

 static void rtc7301_start(struct rtc7301_priv *priv)
 {
 	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP, 0);
 }

 static void rtc7301_select_bank(struct rtc7301_priv *priv, u8 bank)
 {
 	u8 val = 0;

 	if (bank == priv->bank)
 		return;

 	if (bank & BIT(0))
 		val |= RTC7301_CONTROL_BANK_SEL_0;
 	if (bank & BIT(1))
 		val |= RTC7301_CONTROL_BANK_SEL_1;

 	rtc7301_update_bits(priv, RTC7301_CONTROL,
 			    RTC7301_CONTROL_BANK_SEL_0 |
 			    RTC7301_CONTROL_BANK_SEL_1, val);

 	priv->bank = bank;
 }

 static void rtc7301_get_time(struct rtc7301_priv *priv, struct rtc_time *tm,
 			     bool alarm)
 {
 	int year;

 	tm->tm_sec = rtc7301_read(priv, RTC7301_1_SEC);
 	tm->tm_sec += (rtc7301_read(priv, RTC7301_10_SEC) & ~RTC7301_AE) * 10;
 	tm->tm_min = rtc7301_read(priv, RTC7301_1_MIN);
 	tm->tm_min += (rtc7301_read(priv, RTC7301_10_MIN) & ~RTC7301_AE) * 10;
 	tm->tm_hour = rtc7301_read(priv, RTC7301_1_HOUR);
 	tm->tm_hour += (rtc7301_read(priv, RTC7301_10_HOUR) & ~RTC7301_AE) * 10;
 	tm->tm_mday = rtc7301_read(priv, RTC7301_1_DAY);
 	tm->tm_mday += (rtc7301_read(priv, RTC7301_10_DAY) & ~RTC7301_AE) * 10;

 	if (alarm) {
 		tm->tm_wday = -1;
 		tm->tm_mon = -1;
 		tm->tm_year = -1;
 		tm->tm_yday = -1;
 		tm->tm_isdst = -1;
 		return;
 	}

 	tm->tm_wday = (rtc7301_read(priv, RTC7301_DAY_OF_WEEK) & ~RTC7301_AE);
 	tm->tm_mon = rtc7301_read(priv, RTC7301_10_MONTH) * 10 +
 		     rtc7301_read(priv, RTC7301_1_MONTH) - 1;
 	year = rtc7301_read(priv, RTC7301_1000_YEAR) * 1000 +
 	       rtc7301_read(priv, RTC7301_100_YEAR) * 100 +
 	       rtc7301_read(priv, RTC7301_10_YEAR) * 10 +
 	       rtc7301_read(priv, RTC7301_1_YEAR);

 	tm->tm_year = year - 1900;
 }

 static void rtc7301_write_time(struct rtc7301_priv *priv, struct rtc_time *tm,
 			       bool alarm)
 {
 	int year;

 	rtc7301_write(priv, tm->tm_sec % 10, RTC7301_1_SEC);
 	rtc7301_write(priv, tm->tm_sec / 10, RTC7301_10_SEC);

 	rtc7301_write(priv, tm->tm_min % 10, RTC7301_1_MIN);
 	rtc7301_write(priv, tm->tm_min / 10, RTC7301_10_MIN);

 	rtc7301_write(priv, tm->tm_hour % 10, RTC7301_1_HOUR);
 	rtc7301_write(priv, tm->tm_hour / 10, RTC7301_10_HOUR);

 	rtc7301_write(priv, tm->tm_mday % 10, RTC7301_1_DAY);
 	rtc7301_write(priv, tm->tm_mday / 10, RTC7301_10_DAY);

 	/* Don't care for alarm register */
 	rtc7301_write(priv, alarm ? RTC7301_AE : tm->tm_wday,
 		      RTC7301_DAY_OF_WEEK);

 	if (alarm)
 		return;

 	rtc7301_write(priv, (tm->tm_mon + 1) % 10, RTC7301_1_MONTH);
 	rtc7301_write(priv, (tm->tm_mon + 1) / 10, RTC7301_10_MONTH);

 	year = tm->tm_year + 1900;

 	rtc7301_write(priv, year % 10, RTC7301_1_YEAR);
 	rtc7301_write(priv, (year / 10) % 10, RTC7301_10_YEAR);
 	rtc7301_write(priv, (year / 100) % 10, RTC7301_100_YEAR);
 	rtc7301_write(priv, year / 1000, RTC7301_1000_YEAR);
 }

 static void rtc7301_alarm_irq(struct rtc7301_priv *priv, unsigned int enabled)
 {
 	rtc7301_update_bits(priv, RTC7301_ALARM_CONTROL,
 			    RTC7301_ALARM_CONTROL_AF |
 			    RTC7301_ALARM_CONTROL_AIE,
 			    enabled ? RTC7301_ALARM_CONTROL_AIE : 0);
 }

 static int rtc7301_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);
 	unsigned long flags;
 	int err;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_select_bank(priv, 0);

 	err = rtc7301_wait_while_busy(priv);
 	if (!err)
 		rtc7301_get_time(priv, tm, false);

 	spin_unlock_irqrestore(&priv->lock, flags);

 	return err;
 }

 static int rtc7301_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);
 	unsigned long flags;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_stop(priv);
 	udelay(300);
 	rtc7301_select_bank(priv, 0);
 	rtc7301_write_time(priv, tm, false);
 	rtc7301_start(priv);

 	spin_unlock_irqrestore(&priv->lock, flags);

 	return 0;
 }

 static int rtc7301_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);
 	unsigned long flags;
 	u8 alrm_ctrl;

 	if (priv->irq <= 0)
 		return -EINVAL;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_select_bank(priv, 1);
 	rtc7301_get_time(priv, &alarm->time, true);

 	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);

 	alarm->enabled = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AIE);
 	alarm->pending = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AF);

 	spin_unlock_irqrestore(&priv->lock, flags);

 	return 0;
 }

 static int rtc7301_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);
 	unsigned long flags;

 	if (priv->irq <= 0)
 		return -EINVAL;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_select_bank(priv, 1);
 	rtc7301_write_time(priv, &alarm->time, true);
 	rtc7301_alarm_irq(priv, alarm->enabled);

 	spin_unlock_irqrestore(&priv->lock, flags);

 	return 0;
 }

 static int rtc7301_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);
 	unsigned long flags;

 	if (priv->irq <= 0)
 		return -EINVAL;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_select_bank(priv, 1);
 	rtc7301_alarm_irq(priv, enabled);

 	spin_unlock_irqrestore(&priv->lock, flags);

 	return 0;
 }

 static const struct rtc_class_ops rtc7301_rtc_ops = {
 	.read_time	= rtc7301_read_time,
 	.set_time	= rtc7301_set_time,
 	.read_alarm	= rtc7301_read_alarm,
 	.set_alarm	= rtc7301_set_alarm,
 	.alarm_irq_enable = rtc7301_alarm_irq_enable,
 };

 static irqreturn_t rtc7301_irq_handler(int irq, void *dev_id)
 {
 	struct rtc_device *rtc = dev_id;
 	struct rtc7301_priv *priv = dev_get_drvdata(rtc->dev.parent);
 	irqreturn_t ret = IRQ_NONE;
 	u8 alrm_ctrl;

 	spin_lock(&priv->lock);

 	rtc7301_select_bank(priv, 1);

 	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
 	if (alrm_ctrl & RTC7301_ALARM_CONTROL_AF) {
 		ret = IRQ_HANDLED;
 		rtc7301_alarm_irq(priv, false);
 		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
 	}

 	spin_unlock(&priv->lock);

 	return ret;
 }

 static void rtc7301_init(struct rtc7301_priv *priv)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&priv->lock, flags);

 	rtc7301_select_bank(priv, 2);
 	rtc7301_write(priv, 0, RTC7301_TIMER_CONTROL);

 	spin_unlock_irqrestore(&priv->lock, flags);
 }

 static int __init rtc7301_rtc_probe(struct platform_device *dev)
 {
 	void __iomem *regs;
 	struct rtc7301_priv *priv;
 	struct rtc_device *rtc;
 	static const struct regmap_config *mapconf;
 	int ret;
 	u32 val;

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

 	regs = devm_platform_ioremap_resource(dev, 0);
 	if (IS_ERR(regs))
 		return PTR_ERR(regs);

 	ret = device_property_read_u32(&dev->dev, "reg-io-width", &val);
 	if (ret)
 		/* Default to 32bit accesses */
 		val = 4;

 	switch (val) {
 	case 1:
 		mapconf = &rtc7301_regmap_8_config;
 		break;
 	case 4:
 		mapconf = &rtc7301_regmap_32_config;
 		break;
 	default:
 		dev_err(&dev->dev, "invalid reg-io-width %d\n", val);
 		return -EINVAL;
 	}

 	priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
 					     mapconf);
 	if (IS_ERR(priv->regmap))
 		return PTR_ERR(priv->regmap);

 	priv->irq = platform_get_irq(dev, 0);

 	spin_lock_init(&priv->lock);
 	priv->bank = -1;

 	rtc7301_init(priv);

 	platform_set_drvdata(dev, priv);

 	rtc = devm_rtc_device_register(&dev->dev, DRV_NAME, &rtc7301_rtc_ops,
 				       THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	if (priv->irq > 0) {
 		ret = devm_request_irq(&dev->dev, priv->irq,
 				       rtc7301_irq_handler, IRQF_SHARED,
 				       dev_name(&dev->dev), rtc);
 		if (ret) {
 			priv->irq = 0;
 			dev_err(&dev->dev, "unable to request IRQ\n");
 		} else {
 			device_set_wakeup_capable(&dev->dev, true);
 		}
 	}

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP

 static int rtc7301_suspend(struct device *dev)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);

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

 	return 0;
 }

 static int rtc7301_resume(struct device *dev)
 {
 	struct rtc7301_priv *priv = dev_get_drvdata(dev);

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

 	return 0;
 }

 #endif

 static SIMPLE_DEV_PM_OPS(rtc7301_pm_ops, rtc7301_suspend, rtc7301_resume);

 static const struct of_device_id rtc7301_dt_match[] = {
 	{ .compatible = "epson,rtc7301sf" },
 	{ .compatible = "epson,rtc7301dg" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, rtc7301_dt_match);

 static struct platform_driver rtc7301_rtc_driver = {
 	.driver	= {
 		.name = DRV_NAME,
 		.of_match_table = rtc7301_dt_match,
 		.pm = &rtc7301_pm_ops,
 	},
 };

 module_platform_driver_probe(rtc7301_rtc_driver, rtc7301_rtc_probe);

 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("EPSON TOYOCOM RTC-7301SF/DG Driver");
 MODULE_ALIAS("platform:rtc-r7301");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* EPSON TOYOCOM RTC-7301SF/DG Driver
	*
	* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
	*
	* Based on rtc-rp5c01.c
	*
	* Datasheet: http://www5.epsondevice.com/en/products/parallel/rtc7301sf.html
	*/

	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/delay.h>
	#include <linux/property.h>
	#include <linux/regmap.h>
	#include <linux/platform_device.h>
	#include <linux/rtc.h>

	#define DRV_NAME "rtc-r7301"

	#define RTC7301_1_SEC 0x0 /* Bank 0 and Band 1 */
	#define RTC7301_10_SEC 0x1 /* Bank 0 and Band 1 */
	#define RTC7301_AE BIT(3)
	#define RTC7301_1_MIN 0x2 /* Bank 0 and Band 1 */
	#define RTC7301_10_MIN 0x3 /* Bank 0 and Band 1 */
	#define RTC7301_1_HOUR 0x4 /* Bank 0 and Band 1 */
	#define RTC7301_10_HOUR 0x5 /* Bank 0 and Band 1 */
	#define RTC7301_DAY_OF_WEEK 0x6 /* Bank 0 and Band 1 */
	#define RTC7301_1_DAY 0x7 /* Bank 0 and Band 1 */
	#define RTC7301_10_DAY 0x8 /* Bank 0 and Band 1 */
	#define RTC7301_1_MONTH 0x9 /* Bank 0 */
	#define RTC7301_10_MONTH 0xa /* Bank 0 */
	#define RTC7301_1_YEAR 0xb /* Bank 0 */
	#define RTC7301_10_YEAR 0xc /* Bank 0 */
	#define RTC7301_100_YEAR 0xd /* Bank 0 */
	#define RTC7301_1000_YEAR 0xe /* Bank 0 */
	#define RTC7301_ALARM_CONTROL 0xe /* Bank 1 */
	#define RTC7301_ALARM_CONTROL_AIE BIT(0)
	#define RTC7301_ALARM_CONTROL_AF BIT(1)
	#define RTC7301_TIMER_CONTROL 0xe /* Bank 2 */
	#define RTC7301_TIMER_CONTROL_TIE BIT(0)
	#define RTC7301_TIMER_CONTROL_TF BIT(1)
	#define RTC7301_CONTROL 0xf /* All banks */
	#define RTC7301_CONTROL_BUSY BIT(0)
	#define RTC7301_CONTROL_STOP BIT(1)
	#define RTC7301_CONTROL_BANK_SEL_0 BIT(2)
	#define RTC7301_CONTROL_BANK_SEL_1 BIT(3)

	struct rtc7301_priv {
	struct regmap *regmap;
	int irq;
	spinlock_t lock;
	u8 bank;
	};

	/*
	* When the device is memory-mapped, some platforms pack the registers into
	* 32-bit access using the lower 8 bits at each 4-byte stride, while others
	* expose them as simply consecutive bytes.
	*/
	static const struct regmap_config rtc7301_regmap_32_config = {
	.reg_bits = 32,
	.val_bits = 8,
	.reg_stride = 4,
	};

	static const struct regmap_config rtc7301_regmap_8_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.reg_stride = 1,
	};

	static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
	{
	int reg_stride = regmap_get_reg_stride(priv->regmap);
	unsigned int val;

	regmap_read(priv->regmap, reg_stride * reg, &val);

	return val & 0xf;
	}

	static void rtc7301_write(struct rtc7301_priv *priv, u8 val, unsigned int reg)
	{
	int reg_stride = regmap_get_reg_stride(priv->regmap);

	regmap_write(priv->regmap, reg_stride * reg, val);
	}

	static void rtc7301_update_bits(struct rtc7301_priv *priv, unsigned int reg,
	u8 mask, u8 val)
	{
	int reg_stride = regmap_get_reg_stride(priv->regmap);

	regmap_update_bits(priv->regmap, reg_stride * reg, mask, val);
	}

	static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
	{
	int retries = 100;

	while (retries-- > 0) {
	u8 val;

	val = rtc7301_read(priv, RTC7301_CONTROL);
	if (!(val & RTC7301_CONTROL_BUSY))
	return 0;

	udelay(300);
	}

	return -ETIMEDOUT;
	}

	static void rtc7301_stop(struct rtc7301_priv *priv)
	{
	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP,
	RTC7301_CONTROL_STOP);
	}

	static void rtc7301_start(struct rtc7301_priv *priv)
	{
	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP, 0);
	}

	static void rtc7301_select_bank(struct rtc7301_priv *priv, u8 bank)
	{
	u8 val = 0;

	if (bank == priv->bank)
	return;

	if (bank & BIT(0))
	val \|= RTC7301_CONTROL_BANK_SEL_0;
	if (bank & BIT(1))
	val \|= RTC7301_CONTROL_BANK_SEL_1;

	rtc7301_update_bits(priv, RTC7301_CONTROL,
	RTC7301_CONTROL_BANK_SEL_0 \|
	RTC7301_CONTROL_BANK_SEL_1, val);

	priv->bank = bank;
	}

	static void rtc7301_get_time(struct rtc7301_priv priv, struct rtc_time tm,
	bool alarm)
	{
	int year;

	tm->tm_sec = rtc7301_read(priv, RTC7301_1_SEC);
	tm->tm_sec += (rtc7301_read(priv, RTC7301_10_SEC) & ~RTC7301_AE) * 10;
	tm->tm_min = rtc7301_read(priv, RTC7301_1_MIN);
	tm->tm_min += (rtc7301_read(priv, RTC7301_10_MIN) & ~RTC7301_AE) * 10;
	tm->tm_hour = rtc7301_read(priv, RTC7301_1_HOUR);
	tm->tm_hour += (rtc7301_read(priv, RTC7301_10_HOUR) & ~RTC7301_AE) * 10;
	tm->tm_mday = rtc7301_read(priv, RTC7301_1_DAY);
	tm->tm_mday += (rtc7301_read(priv, RTC7301_10_DAY) & ~RTC7301_AE) * 10;

	if (alarm) {
	tm->tm_wday = -1;
	tm->tm_mon = -1;
	tm->tm_year = -1;
	tm->tm_yday = -1;
	tm->tm_isdst = -1;
	return;
	}

	tm->tm_wday = (rtc7301_read(priv, RTC7301_DAY_OF_WEEK) & ~RTC7301_AE);
	tm->tm_mon = rtc7301_read(priv, RTC7301_10_MONTH) * 10 +
	rtc7301_read(priv, RTC7301_1_MONTH) - 1;
	year = rtc7301_read(priv, RTC7301_1000_YEAR) * 1000 +
	rtc7301_read(priv, RTC7301_100_YEAR) * 100 +
	rtc7301_read(priv, RTC7301_10_YEAR) * 10 +
	rtc7301_read(priv, RTC7301_1_YEAR);

	tm->tm_year = year - 1900;
	}

	static void rtc7301_write_time(struct rtc7301_priv priv, struct rtc_time tm,
	bool alarm)
	{
	int year;

	rtc7301_write(priv, tm->tm_sec % 10, RTC7301_1_SEC);
	rtc7301_write(priv, tm->tm_sec / 10, RTC7301_10_SEC);

	rtc7301_write(priv, tm->tm_min % 10, RTC7301_1_MIN);
	rtc7301_write(priv, tm->tm_min / 10, RTC7301_10_MIN);

	rtc7301_write(priv, tm->tm_hour % 10, RTC7301_1_HOUR);
	rtc7301_write(priv, tm->tm_hour / 10, RTC7301_10_HOUR);

	rtc7301_write(priv, tm->tm_mday % 10, RTC7301_1_DAY);
	rtc7301_write(priv, tm->tm_mday / 10, RTC7301_10_DAY);

	/* Don't care for alarm register */
	rtc7301_write(priv, alarm ? RTC7301_AE : tm->tm_wday,
	RTC7301_DAY_OF_WEEK);

	if (alarm)
	return;

	rtc7301_write(priv, (tm->tm_mon + 1) % 10, RTC7301_1_MONTH);
	rtc7301_write(priv, (tm->tm_mon + 1) / 10, RTC7301_10_MONTH);

	year = tm->tm_year + 1900;

	rtc7301_write(priv, year % 10, RTC7301_1_YEAR);
	rtc7301_write(priv, (year / 10) % 10, RTC7301_10_YEAR);
	rtc7301_write(priv, (year / 100) % 10, RTC7301_100_YEAR);
	rtc7301_write(priv, year / 1000, RTC7301_1000_YEAR);
	}

	static void rtc7301_alarm_irq(struct rtc7301_priv *priv, unsigned int enabled)
	{
	rtc7301_update_bits(priv, RTC7301_ALARM_CONTROL,
	RTC7301_ALARM_CONTROL_AF \|
	RTC7301_ALARM_CONTROL_AIE,
	enabled ? RTC7301_ALARM_CONTROL_AIE : 0);
	}

	static int rtc7301_read_time(struct device dev, struct rtc_time tm)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);
	unsigned long flags;
	int err;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_select_bank(priv, 0);

	err = rtc7301_wait_while_busy(priv);
	if (!err)
	rtc7301_get_time(priv, tm, false);

	spin_unlock_irqrestore(&priv->lock, flags);

	return err;
	}

	static int rtc7301_set_time(struct device dev, struct rtc_time tm)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_stop(priv);
	udelay(300);
	rtc7301_select_bank(priv, 0);
	rtc7301_write_time(priv, tm, false);
	rtc7301_start(priv);

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
	}

	static int rtc7301_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);
	unsigned long flags;
	u8 alrm_ctrl;

	if (priv->irq <= 0)
	return -EINVAL;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_select_bank(priv, 1);
	rtc7301_get_time(priv, &alarm->time, true);

	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);

	alarm->enabled = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AIE);
	alarm->pending = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AF);

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
	}

	static int rtc7301_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);
	unsigned long flags;

	if (priv->irq <= 0)
	return -EINVAL;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_select_bank(priv, 1);
	rtc7301_write_time(priv, &alarm->time, true);
	rtc7301_alarm_irq(priv, alarm->enabled);

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
	}

	static int rtc7301_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);
	unsigned long flags;

	if (priv->irq <= 0)
	return -EINVAL;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_select_bank(priv, 1);
	rtc7301_alarm_irq(priv, enabled);

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
	}

	static const struct rtc_class_ops rtc7301_rtc_ops = {
	.read_time = rtc7301_read_time,
	.set_time = rtc7301_set_time,
	.read_alarm = rtc7301_read_alarm,
	.set_alarm = rtc7301_set_alarm,
	.alarm_irq_enable = rtc7301_alarm_irq_enable,
	};

	static irqreturn_t rtc7301_irq_handler(int irq, void *dev_id)
	{
	struct rtc_device *rtc = dev_id;
	struct rtc7301_priv *priv = dev_get_drvdata(rtc->dev.parent);
	irqreturn_t ret = IRQ_NONE;
	u8 alrm_ctrl;

	spin_lock(&priv->lock);

	rtc7301_select_bank(priv, 1);

	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
	if (alrm_ctrl & RTC7301_ALARM_CONTROL_AF) {
	ret = IRQ_HANDLED;
	rtc7301_alarm_irq(priv, false);
	rtc_update_irq(rtc, 1, RTC_IRQF \| RTC_AF);
	}

	spin_unlock(&priv->lock);

	return ret;
	}

	static void rtc7301_init(struct rtc7301_priv *priv)
	{
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);

	rtc7301_select_bank(priv, 2);
	rtc7301_write(priv, 0, RTC7301_TIMER_CONTROL);

	spin_unlock_irqrestore(&priv->lock, flags);
	}

	static int __init rtc7301_rtc_probe(struct platform_device *dev)
	{
	void __iomem *regs;
	struct rtc7301_priv *priv;
	struct rtc_device *rtc;
	static const struct regmap_config *mapconf;
	int ret;
	u32 val;

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

	regs = devm_platform_ioremap_resource(dev, 0);
	if (IS_ERR(regs))
	return PTR_ERR(regs);

	ret = device_property_read_u32(&dev->dev, "reg-io-width", &val);
	if (ret)
	/* Default to 32bit accesses */
	val = 4;

	switch (val) {
	case 1:
	mapconf = &rtc7301_regmap_8_config;
	break;
	case 4:
	mapconf = &rtc7301_regmap_32_config;
	break;
	default:
	dev_err(&dev->dev, "invalid reg-io-width %d\n", val);
	return -EINVAL;
	}

	priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
	mapconf);
	if (IS_ERR(priv->regmap))
	return PTR_ERR(priv->regmap);

	priv->irq = platform_get_irq(dev, 0);

	spin_lock_init(&priv->lock);
	priv->bank = -1;

	rtc7301_init(priv);

	platform_set_drvdata(dev, priv);

	rtc = devm_rtc_device_register(&dev->dev, DRV_NAME, &rtc7301_rtc_ops,
	THIS_MODULE);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	if (priv->irq > 0) {
	ret = devm_request_irq(&dev->dev, priv->irq,
	rtc7301_irq_handler, IRQF_SHARED,
	dev_name(&dev->dev), rtc);
	if (ret) {
	priv->irq = 0;
	dev_err(&dev->dev, "unable to request IRQ\n");
	} else {
	device_set_wakeup_capable(&dev->dev, true);
	}
	}

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP

	static int rtc7301_suspend(struct device *dev)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);

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

	return 0;
	}

	static int rtc7301_resume(struct device *dev)
	{
	struct rtc7301_priv *priv = dev_get_drvdata(dev);

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

	return 0;
	}

	#endif

	static SIMPLE_DEV_PM_OPS(rtc7301_pm_ops, rtc7301_suspend, rtc7301_resume);

	static const struct of_device_id rtc7301_dt_match[] = {
	{ .compatible = "epson,rtc7301sf" },
	{ .compatible = "epson,rtc7301dg" },
	{}
	};
	MODULE_DEVICE_TABLE(of, rtc7301_dt_match);

	static struct platform_driver rtc7301_rtc_driver = {
	.driver = {
	.name = DRV_NAME,
	.of_match_table = rtc7301_dt_match,
	.pm = &rtc7301_pm_ops,
	},
	};

	module_platform_driver_probe(rtc7301_rtc_driver, rtc7301_rtc_probe);

	MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("EPSON TOYOCOM RTC-7301SF/DG Driver");
	MODULE_ALIAS("platform:rtc-r7301");