// SPDX-License-Identifier: GPL-2.0

  /*
   * RTC driver for the Micro Crystal RV8803
   *
   * Copyright (C) 2015 Micro Crystal SA

   * Alexandre Belloni <alexandre.belloni@bootlin.com>

   *

   */
  
  #include <linux/bcd.h>
  #include <linux/bitops.h>

  #include <linux/log2.h>

  #include <linux/i2c.h>
  #include <linux/interrupt.h>
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/of_device.h>

  #include <linux/rtc.h>

  #define RV8803_I2C_TRY_COUNT		4

  #define RV8803_SEC			0x00
  #define RV8803_MIN			0x01
  #define RV8803_HOUR			0x02
  #define RV8803_WEEK			0x03
  #define RV8803_DAY			0x04
  #define RV8803_MONTH			0x05
  #define RV8803_YEAR			0x06
  #define RV8803_RAM			0x07
  #define RV8803_ALARM_MIN		0x08
  #define RV8803_ALARM_HOUR		0x09
  #define RV8803_ALARM_WEEK_OR_DAY	0x0A
  #define RV8803_EXT			0x0D
  #define RV8803_FLAG			0x0E
  #define RV8803_CTRL			0x0F
  
  #define RV8803_EXT_WADA			BIT(6)
  
  #define RV8803_FLAG_V1F			BIT(0)
  #define RV8803_FLAG_V2F			BIT(1)
  #define RV8803_FLAG_AF			BIT(3)
  #define RV8803_FLAG_TF			BIT(4)
  #define RV8803_FLAG_UF			BIT(5)
  
  #define RV8803_CTRL_RESET		BIT(0)
  
  #define RV8803_CTRL_EIE			BIT(2)
  #define RV8803_CTRL_AIE			BIT(3)
  #define RV8803_CTRL_TIE			BIT(4)
  #define RV8803_CTRL_UIE			BIT(5)

  #define RX8900_BACKUP_CTRL		0x18
  #define RX8900_FLAG_SWOFF		BIT(2)
  #define RX8900_FLAG_VDETOFF		BIT(3)
  
  enum rv8803_type {
  	rv_8803,
  	rx_8900
  };

  struct rv8803_data {
  	struct i2c_client *client;
  	struct rtc_device *rtc;

  	struct mutex flags_lock;

  	u8 ctrl;

  	enum rv8803_type type;

  };

  static int rv8803_read_reg(const struct i2c_client *client, u8 reg)
  {
  	int try = RV8803_I2C_TRY_COUNT;
  	s32 ret;
  
  	/*
  	 * There is a 61µs window during which the RTC does not acknowledge I2C
  	 * transfers. In that case, ensure that there are multiple attempts.
  	 */
  	do
  		ret = i2c_smbus_read_byte_data(client, reg);
  	while ((ret == -ENXIO || ret == -EIO) && --try);
  	if (ret < 0)
  		dev_err(&client->dev, "Unable to read register 0x%02x
  ", reg);
  
  	return ret;
  }
  
  static int rv8803_read_regs(const struct i2c_client *client,
  			    u8 reg, u8 count, u8 *values)
  {
  	int try = RV8803_I2C_TRY_COUNT;
  	s32 ret;
  
  	do
  		ret = i2c_smbus_read_i2c_block_data(client, reg, count, values);
  	while ((ret == -ENXIO || ret == -EIO) && --try);
  	if (ret != count) {
  		dev_err(&client->dev,
  			"Unable to read registers 0x%02x..0x%02x
  ",
  			reg, reg + count - 1);
  		return ret < 0 ? ret : -EIO;
  	}
  
  	return 0;
  }
  
  static int rv8803_write_reg(const struct i2c_client *client, u8 reg, u8 value)
  {
  	int try = RV8803_I2C_TRY_COUNT;
  	s32 ret;
  
  	do
  		ret = i2c_smbus_write_byte_data(client, reg, value);
  	while ((ret == -ENXIO || ret == -EIO) && --try);
  	if (ret)
  		dev_err(&client->dev, "Unable to write register 0x%02x
  ", reg);
  
  	return ret;
  }
  
  static int rv8803_write_regs(const struct i2c_client *client,
  			     u8 reg, u8 count, const u8 *values)
  {
  	int try = RV8803_I2C_TRY_COUNT;
  	s32 ret;
  
  	do
  		ret = i2c_smbus_write_i2c_block_data(client, reg, count,
  						     values);
  	while ((ret == -ENXIO || ret == -EIO) && --try);
  	if (ret)
  		dev_err(&client->dev,
  			"Unable to write registers 0x%02x..0x%02x
  ",
  			reg, reg + count - 1);
  
  	return ret;
  }

  static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
  {
  	struct i2c_client *client = dev_id;
  	struct rv8803_data *rv8803 = i2c_get_clientdata(client);
  	unsigned long events = 0;

  	int flags;

  	mutex_lock(&rv8803->flags_lock);

  	flags = rv8803_read_reg(client, RV8803_FLAG);

  	if (flags <= 0) {

  		mutex_unlock(&rv8803->flags_lock);

  		return IRQ_NONE;
  	}
  
  	if (flags & RV8803_FLAG_V1F)
  		dev_warn(&client->dev, "Voltage low, temperature compensation stopped.
  ");
  
  	if (flags & RV8803_FLAG_V2F)
  		dev_warn(&client->dev, "Voltage low, data loss detected.
  ");
  
  	if (flags & RV8803_FLAG_TF) {
  		flags &= ~RV8803_FLAG_TF;
  		rv8803->ctrl &= ~RV8803_CTRL_TIE;
  		events |= RTC_PF;
  	}
  
  	if (flags & RV8803_FLAG_AF) {
  		flags &= ~RV8803_FLAG_AF;
  		rv8803->ctrl &= ~RV8803_CTRL_AIE;
  		events |= RTC_AF;
  	}
  
  	if (flags & RV8803_FLAG_UF) {
  		flags &= ~RV8803_FLAG_UF;
  		rv8803->ctrl &= ~RV8803_CTRL_UIE;
  		events |= RTC_UF;
  	}
  
  	if (events) {
  		rtc_update_irq(rv8803->rtc, 1, events);

  		rv8803_write_reg(client, RV8803_FLAG, flags);
  		rv8803_write_reg(rv8803->client, RV8803_CTRL, rv8803->ctrl);

  	}

  	mutex_unlock(&rv8803->flags_lock);

  
  	return IRQ_HANDLED;
  }
  
  static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
  {
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);
  	u8 date1[7];
  	u8 date2[7];
  	u8 *date = date1;
  	int ret, flags;

  	flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);

  	if (flags < 0)
  		return flags;
  
  	if (flags & RV8803_FLAG_V2F) {
  		dev_warn(dev, "Voltage low, data is invalid.
  ");
  		return -EINVAL;
  	}

  	ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date);
  	if (ret)
  		return ret;

  
  	if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {

  		ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date2);
  		if (ret)
  			return ret;

  
  		if ((date2[RV8803_SEC] & 0x7f) != bin2bcd(59))
  			date = date2;
  	}
  
  	tm->tm_sec  = bcd2bin(date[RV8803_SEC] & 0x7f);
  	tm->tm_min  = bcd2bin(date[RV8803_MIN] & 0x7f);
  	tm->tm_hour = bcd2bin(date[RV8803_HOUR] & 0x3f);

  	tm->tm_wday = ilog2(date[RV8803_WEEK] & 0x7f);

  	tm->tm_mday = bcd2bin(date[RV8803_DAY] & 0x3f);
  	tm->tm_mon  = bcd2bin(date[RV8803_MONTH] & 0x1f) - 1;
  	tm->tm_year = bcd2bin(date[RV8803_YEAR]) + 100;

  	return 0;

  }
  
  static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);
  	u8 date[7];

  	int ctrl, flags, ret;

  	ctrl = rv8803_read_reg(rv8803->client, RV8803_CTRL);
  	if (ctrl < 0)
  		return ctrl;
  
  	/* Stop the clock */
  	ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
  			       ctrl | RV8803_CTRL_RESET);
  	if (ret)
  		return ret;

  	date[RV8803_SEC]   = bin2bcd(tm->tm_sec);
  	date[RV8803_MIN]   = bin2bcd(tm->tm_min);
  	date[RV8803_HOUR]  = bin2bcd(tm->tm_hour);
  	date[RV8803_WEEK]  = 1 << (tm->tm_wday);
  	date[RV8803_DAY]   = bin2bcd(tm->tm_mday);
  	date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1);
  	date[RV8803_YEAR]  = bin2bcd(tm->tm_year - 100);

  	ret = rv8803_write_regs(rv8803->client, RV8803_SEC, 7, date);
  	if (ret)

  		return ret;

  	/* Restart the clock */
  	ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
  			       ctrl & ~RV8803_CTRL_RESET);
  	if (ret)
  		return ret;

  	mutex_lock(&rv8803->flags_lock);

  	flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);

  	if (flags < 0) {

  		mutex_unlock(&rv8803->flags_lock);

  		return flags;
  	}

  	ret = rv8803_write_reg(rv8803->client, RV8803_FLAG,

  			       flags & ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F));

  	mutex_unlock(&rv8803->flags_lock);

  
  	return ret;
  }
  
  static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);
  	struct i2c_client *client = rv8803->client;
  	u8 alarmvals[3];
  	int flags, ret;

  	ret = rv8803_read_regs(client, RV8803_ALARM_MIN, 3, alarmvals);
  	if (ret)
  		return ret;

  	flags = rv8803_read_reg(client, RV8803_FLAG);

  	if (flags < 0)
  		return flags;
  
  	alrm->time.tm_sec  = 0;
  	alrm->time.tm_min  = bcd2bin(alarmvals[0] & 0x7f);
  	alrm->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);

  	alrm->time.tm_mday = bcd2bin(alarmvals[2] & 0x3f);

  
  	alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
  	alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
  
  	return 0;
  }
  
  static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);
  	u8 alarmvals[3];
  	u8 ctrl[2];
  	int ret, err;

  
  	/* The alarm has no seconds, round up to nearest minute */
  	if (alrm->time.tm_sec) {
  		time64_t alarm_time = rtc_tm_to_time64(&alrm->time);
  
  		alarm_time += 60 - alrm->time.tm_sec;
  		rtc_time64_to_tm(alarm_time, &alrm->time);
  	}

  	mutex_lock(&rv8803->flags_lock);

  	ret = rv8803_read_regs(client, RV8803_FLAG, 2, ctrl);
  	if (ret) {

  		mutex_unlock(&rv8803->flags_lock);

  		return ret;

  	}
  
  	alarmvals[0] = bin2bcd(alrm->time.tm_min);
  	alarmvals[1] = bin2bcd(alrm->time.tm_hour);
  	alarmvals[2] = bin2bcd(alrm->time.tm_mday);
  
  	if (rv8803->ctrl & (RV8803_CTRL_AIE | RV8803_CTRL_UIE)) {
  		rv8803->ctrl &= ~(RV8803_CTRL_AIE | RV8803_CTRL_UIE);

  		err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
  				       rv8803->ctrl);

  		if (err) {

  			mutex_unlock(&rv8803->flags_lock);

  			return err;
  		}
  	}
  
  	ctrl[1] &= ~RV8803_FLAG_AF;

  	err = rv8803_write_reg(rv8803->client, RV8803_FLAG, ctrl[1]);

  	mutex_unlock(&rv8803->flags_lock);

  	if (err)
  		return err;

  	err = rv8803_write_regs(rv8803->client, RV8803_ALARM_MIN, 3, alarmvals);

  	if (err)
  		return err;
  
  	if (alrm->enabled) {
  		if (rv8803->rtc->uie_rtctimer.enabled)
  			rv8803->ctrl |= RV8803_CTRL_UIE;
  		if (rv8803->rtc->aie_timer.enabled)
  			rv8803->ctrl |= RV8803_CTRL_AIE;

  		err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
  				       rv8803->ctrl);

  		if (err)
  			return err;
  	}
  
  	return 0;
  }
  
  static int rv8803_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);
  	int ctrl, flags, err;

  
  	ctrl = rv8803->ctrl;
  
  	if (enabled) {
  		if (rv8803->rtc->uie_rtctimer.enabled)
  			ctrl |= RV8803_CTRL_UIE;
  		if (rv8803->rtc->aie_timer.enabled)
  			ctrl |= RV8803_CTRL_AIE;
  	} else {
  		if (!rv8803->rtc->uie_rtctimer.enabled)
  			ctrl &= ~RV8803_CTRL_UIE;
  		if (!rv8803->rtc->aie_timer.enabled)
  			ctrl &= ~RV8803_CTRL_AIE;
  	}

  	mutex_lock(&rv8803->flags_lock);

  	flags = rv8803_read_reg(client, RV8803_FLAG);

  	if (flags < 0) {

  		mutex_unlock(&rv8803->flags_lock);

  		return flags;
  	}
  	flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);

  	err = rv8803_write_reg(client, RV8803_FLAG, flags);

  	mutex_unlock(&rv8803->flags_lock);

  	if (err)
  		return err;
  
  	if (ctrl != rv8803->ctrl) {
  		rv8803->ctrl = ctrl;

  		err = rv8803_write_reg(client, RV8803_CTRL, rv8803->ctrl);

  		if (err)
  			return err;
  	}
  
  	return 0;
  }
  
  static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct rv8803_data *rv8803 = dev_get_drvdata(dev);

  	unsigned int vl = 0;

  	int flags, ret = 0;

  
  	switch (cmd) {
  	case RTC_VL_READ:

  		flags = rv8803_read_reg(client, RV8803_FLAG);

  		if (flags < 0)
  			return flags;

  		if (flags & RV8803_FLAG_V1F) {

  			dev_warn(&client->dev, "Voltage low, temperature compensation stopped.
  ");

  			vl = RTC_VL_ACCURACY_LOW;
  		}

  
  		if (flags & RV8803_FLAG_V2F)

  			vl |= RTC_VL_DATA_INVALID;

  		return put_user(vl, (unsigned int __user *)arg);

  
  	case RTC_VL_CLR:

  		mutex_lock(&rv8803->flags_lock);

  		flags = rv8803_read_reg(client, RV8803_FLAG);

  		if (flags < 0) {

  			mutex_unlock(&rv8803->flags_lock);

  			return flags;
  		}

  		flags &= ~RV8803_FLAG_V1F;

  		ret = rv8803_write_reg(client, RV8803_FLAG, flags);

  		mutex_unlock(&rv8803->flags_lock);

  		if (ret)

  			return ret;
  
  		return 0;
  
  	default:
  		return -ENOIOCTLCMD;
  	}
  }

  static int rv8803_nvram_write(void *priv, unsigned int offset, void *val,
  			      size_t bytes)

  {

  	return rv8803_write_reg(priv, RV8803_RAM, *(u8 *)val);

  }

  static int rv8803_nvram_read(void *priv, unsigned int offset,
  			     void *val, size_t bytes)

  {

  	int ret;

  	ret = rv8803_read_reg(priv, RV8803_RAM);

  	if (ret < 0)
  		return ret;

  	*(u8 *)val = ret;

  	return 0;

  }

  static struct rtc_class_ops rv8803_rtc_ops = {
  	.read_time = rv8803_get_time,
  	.set_time = rv8803_set_time,
  	.ioctl = rv8803_ioctl,
  };

  static int rx8900_trickle_charger_init(struct rv8803_data *rv8803)
  {
  	struct i2c_client *client = rv8803->client;
  	struct device_node *node = client->dev.of_node;
  	int err;
  	u8 flags;
  
  	if (!node)
  		return 0;
  
  	if (rv8803->type != rx_8900)
  		return 0;
  
  	err = i2c_smbus_read_byte_data(rv8803->client, RX8900_BACKUP_CTRL);
  	if (err < 0)
  		return err;
  
  	flags = ~(RX8900_FLAG_VDETOFF | RX8900_FLAG_SWOFF) & (u8)err;
  
  	if (of_property_read_bool(node, "epson,vdet-disable"))
  		flags |= RX8900_FLAG_VDETOFF;
  
  	if (of_property_read_bool(node, "trickle-diode-disable"))
  		flags |= RX8900_FLAG_SWOFF;
  
  	return i2c_smbus_write_byte_data(rv8803->client, RX8900_BACKUP_CTRL,
  					 flags);
  }

  static int rv8803_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {

  	struct i2c_adapter *adapter = client->adapter;

  	struct rv8803_data *rv8803;

  	int err, flags;

  	struct nvmem_config nvmem_cfg = {
  		.name = "rv8803_nvram",
  		.word_size = 1,
  		.stride = 1,
  		.size = 1,
  		.reg_read = rv8803_nvram_read,
  		.reg_write = rv8803_nvram_write,
  		.priv = client,
  	};

  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
  				     I2C_FUNC_SMBUS_I2C_BLOCK)) {
  		dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK
  ");
  		return -EIO;
  	}
  
  	rv8803 = devm_kzalloc(&client->dev, sizeof(struct rv8803_data),
  			      GFP_KERNEL);
  	if (!rv8803)
  		return -ENOMEM;

  	mutex_init(&rv8803->flags_lock);

  	rv8803->client = client;

  	if (client->dev.of_node)
  		rv8803->type = (enum rv8803_type)
  			of_device_get_match_data(&client->dev);
  	else
  		rv8803->type = id->driver_data;

  	i2c_set_clientdata(client, rv8803);

  	flags = rv8803_read_reg(client, RV8803_FLAG);

  	if (flags < 0)
  		return flags;
  
  	if (flags & RV8803_FLAG_V1F)
  		dev_warn(&client->dev, "Voltage low, temperature compensation stopped.
  ");
  
  	if (flags & RV8803_FLAG_V2F)
  		dev_warn(&client->dev, "Voltage low, data loss detected.
  ");
  
  	if (flags & RV8803_FLAG_AF)
  		dev_warn(&client->dev, "An alarm maybe have been missed.
  ");

  	rv8803->rtc = devm_rtc_allocate_device(&client->dev);

  	if (IS_ERR(rv8803->rtc))

  		return PTR_ERR(rv8803->rtc);

  	if (client->irq > 0) {
  		err = devm_request_threaded_irq(&client->dev, client->irq,
  						NULL, rv8803_handle_irq,
  						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
  						"rv8803", client);
  		if (err) {
  			dev_warn(&client->dev, "unable to request IRQ, alarms disabled
  ");
  			client->irq = 0;
  		} else {
  			rv8803_rtc_ops.read_alarm = rv8803_get_alarm;
  			rv8803_rtc_ops.set_alarm = rv8803_set_alarm;
  			rv8803_rtc_ops.alarm_irq_enable = rv8803_alarm_irq_enable;
  		}
  	}

  	err = rv8803_write_reg(rv8803->client, RV8803_EXT, RV8803_EXT_WADA);

  	if (err)
  		return err;

  	err = rx8900_trickle_charger_init(rv8803);
  	if (err) {
  		dev_err(&client->dev, "failed to init charger
  ");
  		return err;
  	}

  	rv8803->rtc->ops = &rv8803_rtc_ops;
  	rv8803->rtc->nvram_old_abi = true;

  	rv8803->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
  	rv8803->rtc->range_max = RTC_TIMESTAMP_END_2099;

  	err = rtc_register_device(rv8803->rtc);
  	if (err)
  		return err;
  
  	rtc_nvmem_register(rv8803->rtc, &nvmem_cfg);

  	rv8803->rtc->max_user_freq = 1;
  
  	return 0;
  }

  static const struct i2c_device_id rv8803_id[] = {

  	{ "rv8803", rv_8803 },

  	{ "rx8803", rv_8803 },

  	{ "rx8900", rx_8900 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, rv8803_id);

  static const struct of_device_id rv8803_of_match[] = {
  	{
  		.compatible = "microcrystal,rv8803",

  		.data = (void *)rv_8803

  	},
  	{

  		.compatible = "epson,rx8803",
  		.data = (void *)rv_8803
  	},
  	{

  		.compatible = "epson,rx8900",
  		.data = (void *)rx_8900
  	},
  	{ }
  };
  MODULE_DEVICE_TABLE(of, rv8803_of_match);

  static struct i2c_driver rv8803_driver = {
  	.driver = {
  		.name = "rtc-rv8803",

  		.of_match_table = of_match_ptr(rv8803_of_match),

  	},
  	.probe		= rv8803_probe,

  	.id_table	= rv8803_id,
  };
  module_i2c_driver(rv8803_driver);

  MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@bootlin.com>");

  MODULE_DESCRIPTION("Micro Crystal RV8803 RTC driver");
  MODULE_LICENSE("GPL v2");