// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Driver for the Epson RTC module RX-8010 SJ
   *
   * Copyright(C) Timesys Corporation 2015
   * Copyright(C) General Electric Company 2015

   */
  
  #include <linux/bcd.h>
  #include <linux/bitops.h>
  #include <linux/i2c.h>
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/regmap.h>

  #include <linux/rtc.h>

  #define RX8010_SEC		0x10
  #define RX8010_MIN		0x11
  #define RX8010_HOUR		0x12
  #define RX8010_WDAY		0x13
  #define RX8010_MDAY		0x14
  #define RX8010_MONTH		0x15
  #define RX8010_YEAR		0x16
  #define RX8010_RESV17		0x17
  #define RX8010_ALMIN		0x18
  #define RX8010_ALHOUR		0x19
  #define RX8010_ALWDAY		0x1A
  #define RX8010_TCOUNT0		0x1B
  #define RX8010_TCOUNT1		0x1C
  #define RX8010_EXT		0x1D
  #define RX8010_FLAG		0x1E
  #define RX8010_CTRL		0x1F

  /* 0x20 to 0x2F are user registers */

  #define RX8010_RESV30		0x30
  #define RX8010_RESV31		0x31
  #define RX8010_IRQ		0x32

  #define RX8010_EXT_WADA		BIT(3)

  #define RX8010_FLAG_VLF		BIT(1)
  #define RX8010_FLAG_AF		BIT(3)
  #define RX8010_FLAG_TF		BIT(4)
  #define RX8010_FLAG_UF		BIT(5)

  #define RX8010_CTRL_AIE		BIT(3)
  #define RX8010_CTRL_UIE		BIT(5)
  #define RX8010_CTRL_STOP	BIT(6)
  #define RX8010_CTRL_TEST	BIT(7)

  #define RX8010_ALARM_AE		BIT(7)

  
  static const struct i2c_device_id rx8010_id[] = {
  	{ "rx8010", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, rx8010_id);

  static const struct of_device_id rx8010_of_match[] = {
  	{ .compatible = "epson,rx8010" },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, rx8010_of_match);

  struct rx8010_data {

  	struct regmap *regs;

  	struct rtc_device *rtc;
  	u8 ctrlreg;

  };
  
  static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
  {
  	struct i2c_client *client = dev_id;
  	struct rx8010_data *rx8010 = i2c_get_clientdata(client);

  	int flagreg, err;

  	mutex_lock(&rx8010->rtc->ops_lock);

  	err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
  	if (err) {

  		mutex_unlock(&rx8010->rtc->ops_lock);

  		return IRQ_NONE;
  	}
  
  	if (flagreg & RX8010_FLAG_VLF)
  		dev_warn(&client->dev, "Frequency stop detected
  ");
  
  	if (flagreg & RX8010_FLAG_TF) {
  		flagreg &= ~RX8010_FLAG_TF;
  		rtc_update_irq(rx8010->rtc, 1, RTC_PF | RTC_IRQF);
  	}
  
  	if (flagreg & RX8010_FLAG_AF) {
  		flagreg &= ~RX8010_FLAG_AF;
  		rtc_update_irq(rx8010->rtc, 1, RTC_AF | RTC_IRQF);
  	}
  
  	if (flagreg & RX8010_FLAG_UF) {
  		flagreg &= ~RX8010_FLAG_UF;
  		rtc_update_irq(rx8010->rtc, 1, RTC_UF | RTC_IRQF);
  	}

  	err = regmap_write(rx8010->regs, RX8010_FLAG, flagreg);

  	mutex_unlock(&rx8010->rtc->ops_lock);

  	return err ? IRQ_NONE : IRQ_HANDLED;

  }
  
  static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
  {
  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	u8 date[RX8010_YEAR - RX8010_SEC + 1];

  	int flagreg, err;

  	err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
  	if (err)
  		return err;

  
  	if (flagreg & RX8010_FLAG_VLF) {
  		dev_warn(dev, "Frequency stop detected
  ");
  		return -EINVAL;
  	}

  	err = regmap_bulk_read(rx8010->regs, RX8010_SEC, date, sizeof(date));
  	if (err)
  		return err;

  
  	dt->tm_sec = bcd2bin(date[RX8010_SEC - RX8010_SEC] & 0x7f);
  	dt->tm_min = bcd2bin(date[RX8010_MIN - RX8010_SEC] & 0x7f);
  	dt->tm_hour = bcd2bin(date[RX8010_HOUR - RX8010_SEC] & 0x3f);
  	dt->tm_mday = bcd2bin(date[RX8010_MDAY - RX8010_SEC] & 0x3f);
  	dt->tm_mon = bcd2bin(date[RX8010_MONTH - RX8010_SEC] & 0x1f) - 1;
  	dt->tm_year = bcd2bin(date[RX8010_YEAR - RX8010_SEC]) + 100;
  	dt->tm_wday = ffs(date[RX8010_WDAY - RX8010_SEC] & 0x7f);

  	return 0;

  }
  
  static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
  {
  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	u8 date[RX8010_YEAR - RX8010_SEC + 1];

  	int err;

  	/* set STOP bit before changing clock/calendar */

  	err = regmap_set_bits(rx8010->regs, RX8010_CTRL, RX8010_CTRL_STOP);
  	if (err)

  		return err;

  
  	date[RX8010_SEC - RX8010_SEC] = bin2bcd(dt->tm_sec);
  	date[RX8010_MIN - RX8010_SEC] = bin2bcd(dt->tm_min);
  	date[RX8010_HOUR - RX8010_SEC] = bin2bcd(dt->tm_hour);
  	date[RX8010_MDAY - RX8010_SEC] = bin2bcd(dt->tm_mday);
  	date[RX8010_MONTH - RX8010_SEC] = bin2bcd(dt->tm_mon + 1);
  	date[RX8010_YEAR - RX8010_SEC] = bin2bcd(dt->tm_year - 100);
  	date[RX8010_WDAY - RX8010_SEC] = bin2bcd(1 << dt->tm_wday);

  	err = regmap_bulk_write(rx8010->regs, RX8010_SEC, date, sizeof(date));
  	if (err)

  		return err;

  
  	/* clear STOP bit after changing clock/calendar */

  	err = regmap_clear_bits(rx8010->regs, RX8010_CTRL, RX8010_CTRL_STOP);
  	if (err)

  		return err;

  	err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_VLF);
  	if (err)
  		return err;

  	return 0;
  }

  static int rx8010_init(struct device *dev)

  {

  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	u8 ctrl[2];

  	int need_clear = 0, err;

  
  	/* Initialize reserved registers as specified in datasheet */

  	err = regmap_write(rx8010->regs, RX8010_RESV17, 0xD8);
  	if (err)

  		return err;

  	err = regmap_write(rx8010->regs, RX8010_RESV30, 0x00);
  	if (err)

  		return err;

  	err = regmap_write(rx8010->regs, RX8010_RESV31, 0x08);
  	if (err)

  		return err;

  	err = regmap_write(rx8010->regs, RX8010_IRQ, 0x00);
  	if (err)

  		return err;

  	err = regmap_bulk_read(rx8010->regs, RX8010_FLAG, ctrl, 2);
  	if (err)
  		return err;

  
  	if (ctrl[0] & RX8010_FLAG_VLF)

  		dev_warn(dev, "Frequency stop was detected
  ");

  
  	if (ctrl[0] & RX8010_FLAG_AF) {

  		dev_warn(dev, "Alarm was detected
  ");

  		need_clear = 1;
  	}
  
  	if (ctrl[0] & RX8010_FLAG_TF)
  		need_clear = 1;
  
  	if (ctrl[0] & RX8010_FLAG_UF)
  		need_clear = 1;
  
  	if (need_clear) {
  		ctrl[0] &= ~(RX8010_FLAG_AF | RX8010_FLAG_TF | RX8010_FLAG_UF);

  		err = regmap_write(rx8010->regs, RX8010_FLAG, ctrl[0]);
  		if (err)

  			return err;
  	}
  
  	rx8010->ctrlreg = (ctrl[1] & ~RX8010_CTRL_TEST);

  	return 0;

  }
  
  static int rx8010_read_alarm(struct device *dev, struct rtc_wkalrm *t)
  {
  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	u8 alarmvals[3];

  	int flagreg, err;

  	err = regmap_bulk_read(rx8010->regs, RX8010_ALMIN, alarmvals, 3);
  	if (err)
  		return err;

  	err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
  	if (err)
  		return err;

  
  	t->time.tm_sec = 0;
  	t->time.tm_min = bcd2bin(alarmvals[0] & 0x7f);
  	t->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);

  	if (!(alarmvals[2] & RX8010_ALARM_AE))

  		t->time.tm_mday = bcd2bin(alarmvals[2] & 0x7f);

  	t->enabled = !!(rx8010->ctrlreg & RX8010_CTRL_AIE);
  	t->pending = (flagreg & RX8010_FLAG_AF) && t->enabled;

  	return 0;

  }
  
  static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t)
  {

  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);
  	u8 alarmvals[3];

  	int err;

  
  	if (rx8010->ctrlreg & (RX8010_CTRL_AIE | RX8010_CTRL_UIE)) {
  		rx8010->ctrlreg &= ~(RX8010_CTRL_AIE | RX8010_CTRL_UIE);

  		err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
  		if (err)

  			return err;

  	}

  	err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_AF);
  	if (err)

  		return err;
  
  	alarmvals[0] = bin2bcd(t->time.tm_min);
  	alarmvals[1] = bin2bcd(t->time.tm_hour);
  	alarmvals[2] = bin2bcd(t->time.tm_mday);

  	err = regmap_bulk_write(rx8010->regs, RX8010_ALMIN, alarmvals, 2);
  	if (err)

  		return err;

  	err = regmap_clear_bits(rx8010->regs, RX8010_EXT, RX8010_EXT_WADA);
  	if (err)

  		return err;
  
  	if (alarmvals[2] == 0)
  		alarmvals[2] |= RX8010_ALARM_AE;

  	err = regmap_write(rx8010->regs, RX8010_ALWDAY, alarmvals[2]);
  	if (err)

  		return err;
  
  	if (t->enabled) {
  		if (rx8010->rtc->uie_rtctimer.enabled)
  			rx8010->ctrlreg |= RX8010_CTRL_UIE;
  		if (rx8010->rtc->aie_timer.enabled)
  			rx8010->ctrlreg |=
  				(RX8010_CTRL_AIE | RX8010_CTRL_UIE);

  		err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
  		if (err)

  			return err;
  	}
  
  	return 0;
  }
  
  static int rx8010_alarm_irq_enable(struct device *dev,
  				   unsigned int enabled)
  {

  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	int err;

  	u8 ctrl;

  
  	ctrl = rx8010->ctrlreg;
  
  	if (enabled) {
  		if (rx8010->rtc->uie_rtctimer.enabled)
  			ctrl |= RX8010_CTRL_UIE;
  		if (rx8010->rtc->aie_timer.enabled)
  			ctrl |= (RX8010_CTRL_AIE | RX8010_CTRL_UIE);
  	} else {
  		if (!rx8010->rtc->uie_rtctimer.enabled)
  			ctrl &= ~RX8010_CTRL_UIE;
  		if (!rx8010->rtc->aie_timer.enabled)
  			ctrl &= ~RX8010_CTRL_AIE;
  	}

  	err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_AF);
  	if (err)

  		return err;
  
  	if (ctrl != rx8010->ctrlreg) {
  		rx8010->ctrlreg = ctrl;

  		err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
  		if (err)

  			return err;
  	}
  
  	return 0;
  }
  
  static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
  {

  	struct rx8010_data *rx8010 = dev_get_drvdata(dev);

  	int tmp, flagreg, err;

  
  	switch (cmd) {
  	case RTC_VL_READ:

  		err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
  		if (err)
  			return err;

  		tmp = flagreg & RX8010_FLAG_VLF ? RTC_VL_DATA_INVALID : 0;
  		return put_user(tmp, (unsigned int __user *)arg);

  	default:
  		return -ENOIOCTLCMD;
  	}
  }

  static const struct rtc_class_ops rx8010_rtc_ops_default = {

  	.read_time = rx8010_get_time,
  	.set_time = rx8010_set_time,
  	.ioctl = rx8010_ioctl,
  };

  static const struct rtc_class_ops rx8010_rtc_ops_alarm = {
  	.read_time = rx8010_get_time,
  	.set_time = rx8010_set_time,
  	.ioctl = rx8010_ioctl,
  	.read_alarm = rx8010_read_alarm,
  	.set_alarm = rx8010_set_alarm,
  	.alarm_irq_enable = rx8010_alarm_irq_enable,
  };

  static const struct regmap_config rx8010_regmap_config = {
  	.name = "rx8010-rtc",
  	.reg_bits = 8,
  	.val_bits = 8,
  };

  static int rx8010_probe(struct i2c_client *client)

  {

  	struct device *dev = &client->dev;

  	struct rx8010_data *rx8010;
  	int err = 0;

  	rx8010 = devm_kzalloc(dev, sizeof(*rx8010), GFP_KERNEL);

  	if (!rx8010)
  		return -ENOMEM;

  	i2c_set_clientdata(client, rx8010);

  	rx8010->regs = devm_regmap_init_i2c(client, &rx8010_regmap_config);
  	if (IS_ERR(rx8010->regs))
  		return PTR_ERR(rx8010->regs);

  	err = rx8010_init(dev);

  	if (err)
  		return err;

  	rx8010->rtc = devm_rtc_allocate_device(dev);
  	if (IS_ERR(rx8010->rtc))
  		return PTR_ERR(rx8010->rtc);

  	if (client->irq > 0) {

  		dev_info(dev, "IRQ %d supplied
  ", client->irq);
  		err = devm_request_threaded_irq(dev, client->irq, NULL,

  						rx8010_irq_1_handler,
  						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
  						"rx8010", client);

  		if (err) {

  			dev_err(dev, "unable to request IRQ
  ");

  			return err;

  		}

  		rx8010->rtc->ops = &rx8010_rtc_ops_alarm;

  	} else {

  		rx8010->rtc->ops = &rx8010_rtc_ops_default;

  	}
  
  	rx8010->rtc->max_user_freq = 1;

  	rx8010->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
  	rx8010->rtc->range_max = RTC_TIMESTAMP_END_2099;

  	return rtc_register_device(rx8010->rtc);

  }
  
  static struct i2c_driver rx8010_driver = {
  	.driver = {
  		.name = "rtc-rx8010",

  		.of_match_table = of_match_ptr(rx8010_of_match),

  	},

  	.probe_new	= rx8010_probe,

  	.id_table	= rx8010_id,
  };
  
  module_i2c_driver(rx8010_driver);
  
  MODULE_AUTHOR("Akshay Bhat <akshay.bhat@timesys.com>");
  MODULE_DESCRIPTION("Epson RX8010SJ RTC driver");
  MODULE_LICENSE("GPL v2");