drivers/rtc/rtc-abx80x.c - linux - Git at Google

 /*
  * A driver for the I2C members of the Abracon AB x8xx RTC family,
  * and compatible: AB 1805 and AB 0805
  *
  * Copyright 2014-2015 Macq S.A.
  *
  * Author: Philippe De Muyter <phdm@macqel.be>
  * Author: Alexandre Belloni <alexandre.belloni@free-electrons.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  */

 #include <linux/bcd.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/watchdog.h>

 #define ABX8XX_REG_HTH		0x00
 #define ABX8XX_REG_SC		0x01
 #define ABX8XX_REG_MN		0x02
 #define ABX8XX_REG_HR		0x03
 #define ABX8XX_REG_DA		0x04
 #define ABX8XX_REG_MO		0x05
 #define ABX8XX_REG_YR		0x06
 #define ABX8XX_REG_WD		0x07

 #define ABX8XX_REG_AHTH		0x08
 #define ABX8XX_REG_ASC		0x09
 #define ABX8XX_REG_AMN		0x0a
 #define ABX8XX_REG_AHR		0x0b
 #define ABX8XX_REG_ADA		0x0c
 #define ABX8XX_REG_AMO		0x0d
 #define ABX8XX_REG_AWD		0x0e

 #define ABX8XX_REG_STATUS	0x0f
 #define ABX8XX_STATUS_AF	BIT(2)
 #define ABX8XX_STATUS_WDT	BIT(6)

 #define ABX8XX_REG_CTRL1	0x10
 #define ABX8XX_CTRL_WRITE	BIT(0)
 #define ABX8XX_CTRL_ARST	BIT(2)
 #define ABX8XX_CTRL_12_24	BIT(6)

 #define ABX8XX_REG_IRQ		0x12
 #define ABX8XX_IRQ_AIE		BIT(2)
 #define ABX8XX_IRQ_IM_1_4	(0x3 << 5)

 #define ABX8XX_REG_CD_TIMER_CTL	0x18

 #define ABX8XX_REG_OSC		0x1c
 #define ABX8XX_OSC_FOS		BIT(3)
 #define ABX8XX_OSC_BOS		BIT(4)
 #define ABX8XX_OSC_ACAL_512	BIT(5)
 #define ABX8XX_OSC_ACAL_1024	BIT(6)

 #define ABX8XX_OSC_OSEL		BIT(7)

 #define ABX8XX_REG_OSS		0x1d
 #define ABX8XX_OSS_OF		BIT(1)
 #define ABX8XX_OSS_OMODE	BIT(4)

 #define ABX8XX_REG_WDT		0x1b
 #define ABX8XX_WDT_WDS		BIT(7)
 #define ABX8XX_WDT_BMB_MASK	0x7c
 #define ABX8XX_WDT_BMB_SHIFT	2
 #define ABX8XX_WDT_MAX_TIME	(ABX8XX_WDT_BMB_MASK >> ABX8XX_WDT_BMB_SHIFT)
 #define ABX8XX_WDT_WRB_MASK	0x03
 #define ABX8XX_WDT_WRB_1HZ	0x02

 #define ABX8XX_REG_CFG_KEY	0x1f
 #define ABX8XX_CFG_KEY_OSC	0xa1
 #define ABX8XX_CFG_KEY_MISC	0x9d

 #define ABX8XX_REG_ID0		0x28

 #define ABX8XX_REG_TRICKLE	0x20
 #define ABX8XX_TRICKLE_CHARGE_ENABLE	0xa0
 #define ABX8XX_TRICKLE_STANDARD_DIODE	0x8
 #define ABX8XX_TRICKLE_SCHOTTKY_DIODE	0x4

 static u8 trickle_resistors[] = {0, 3, 6, 11};

 enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
 	AB1801, AB1803, AB1804, AB1805, ABX80X};

 struct abx80x_cap {
 	u16 pn;
 	bool has_tc;
 	bool has_wdog;
 };

 static struct abx80x_cap abx80x_caps[] = {
 	[AB0801] = {.pn = 0x0801},
 	[AB0803] = {.pn = 0x0803},
 	[AB0804] = {.pn = 0x0804, .has_tc = true, .has_wdog = true},
 	[AB0805] = {.pn = 0x0805, .has_tc = true, .has_wdog = true},
 	[AB1801] = {.pn = 0x1801},
 	[AB1803] = {.pn = 0x1803},
 	[AB1804] = {.pn = 0x1804, .has_tc = true, .has_wdog = true},
 	[AB1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
 	[ABX80X] = {.pn = 0}
 };

 struct abx80x_priv {
 	struct rtc_device *rtc;
 	struct i2c_client *client;
 	struct watchdog_device wdog;
 };

 static int abx80x_is_rc_mode(struct i2c_client *client)
 {
 	int flags = 0;

 	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
 	if (flags < 0) {
 		dev_err(&client->dev,
 			"Failed to read autocalibration attribute\n");
 		return flags;
 	}

 	return (flags & ABX8XX_OSS_OMODE) ? 1 : 0;
 }

 static int abx80x_enable_trickle_charger(struct i2c_client *client,
 					 u8 trickle_cfg)
 {
 	int err;

 	/*
 	 * Write the configuration key register to enable access to the Trickle
 	 * register
 	 */
 	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
 					ABX8XX_CFG_KEY_MISC);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write configuration key\n");
 		return -EIO;
 	}

 	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_TRICKLE,
 					ABX8XX_TRICKLE_CHARGE_ENABLE |
 					trickle_cfg);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write trickle register\n");
 		return -EIO;
 	}

 	return 0;
 }

 static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[8];
 	int err, flags, rc_mode = 0;

 	/* Read the Oscillator Failure only in XT mode */
 	rc_mode = abx80x_is_rc_mode(client);
 	if (rc_mode < 0)
 		return rc_mode;

 	if (!rc_mode) {
 		flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
 		if (flags < 0)
 			return flags;

 		if (flags & ABX8XX_OSS_OF) {
 			dev_err(dev, "Oscillator failure, data is invalid.\n");
 			return -EINVAL;
 		}
 	}

 	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_HTH,
 					    sizeof(buf), buf);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to read date\n");
 		return -EIO;
 	}

 	tm->tm_sec = bcd2bin(buf[ABX8XX_REG_SC] & 0x7F);
 	tm->tm_min = bcd2bin(buf[ABX8XX_REG_MN] & 0x7F);
 	tm->tm_hour = bcd2bin(buf[ABX8XX_REG_HR] & 0x3F);
 	tm->tm_wday = buf[ABX8XX_REG_WD] & 0x7;
 	tm->tm_mday = bcd2bin(buf[ABX8XX_REG_DA] & 0x3F);
 	tm->tm_mon = bcd2bin(buf[ABX8XX_REG_MO] & 0x1F) - 1;
 	tm->tm_year = bcd2bin(buf[ABX8XX_REG_YR]) + 100;

 	return 0;
 }

 static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[8];
 	int err, flags;

 	if (tm->tm_year < 100)
 		return -EINVAL;

 	buf[ABX8XX_REG_HTH] = 0;
 	buf[ABX8XX_REG_SC] = bin2bcd(tm->tm_sec);
 	buf[ABX8XX_REG_MN] = bin2bcd(tm->tm_min);
 	buf[ABX8XX_REG_HR] = bin2bcd(tm->tm_hour);
 	buf[ABX8XX_REG_DA] = bin2bcd(tm->tm_mday);
 	buf[ABX8XX_REG_MO] = bin2bcd(tm->tm_mon + 1);
 	buf[ABX8XX_REG_YR] = bin2bcd(tm->tm_year - 100);
 	buf[ABX8XX_REG_WD] = tm->tm_wday;

 	err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_HTH,
 					     sizeof(buf), buf);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write to date registers\n");
 		return -EIO;
 	}

 	/* Clear the OF bit of Oscillator Status Register */
 	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
 	if (flags < 0)
 		return flags;

 	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSS,
 					flags & ~ABX8XX_OSS_OF);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write oscillator status register\n");
 		return err;
 	}

 	return 0;
 }

 static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
 {
 	struct i2c_client *client = dev_id;
 	struct abx80x_priv *priv = i2c_get_clientdata(client);
 	struct rtc_device *rtc = priv->rtc;
 	int status;

 	status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
 	if (status < 0)
 		return IRQ_NONE;

 	if (status & ABX8XX_STATUS_AF)
 		rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);

 	/*
 	 * It is unclear if we'll get an interrupt before the external
 	 * reset kicks in.
 	 */
 	if (status & ABX8XX_STATUS_WDT)
 		dev_alert(&client->dev, "watchdog timeout interrupt.\n");

 	i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);

 	return IRQ_HANDLED;
 }

 static int abx80x_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[7];

 	int irq_mask, err;

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

 	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ASC,
 					    sizeof(buf), buf);
 	if (err)
 		return err;

 	irq_mask = i2c_smbus_read_byte_data(client, ABX8XX_REG_IRQ);
 	if (irq_mask < 0)
 		return irq_mask;

 	t->time.tm_sec = bcd2bin(buf[0] & 0x7F);
 	t->time.tm_min = bcd2bin(buf[1] & 0x7F);
 	t->time.tm_hour = bcd2bin(buf[2] & 0x3F);
 	t->time.tm_mday = bcd2bin(buf[3] & 0x3F);
 	t->time.tm_mon = bcd2bin(buf[4] & 0x1F) - 1;
 	t->time.tm_wday = buf[5] & 0x7;

 	t->enabled = !!(irq_mask & ABX8XX_IRQ_AIE);
 	t->pending = (buf[6] & ABX8XX_STATUS_AF) && t->enabled;

 	return err;
 }

 static int abx80x_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	u8 alarm[6];
 	int err;

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

 	alarm[0] = 0x0;
 	alarm[1] = bin2bcd(t->time.tm_sec);
 	alarm[2] = bin2bcd(t->time.tm_min);
 	alarm[3] = bin2bcd(t->time.tm_hour);
 	alarm[4] = bin2bcd(t->time.tm_mday);
 	alarm[5] = bin2bcd(t->time.tm_mon + 1);

 	err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_AHTH,
 					     sizeof(alarm), alarm);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write alarm registers\n");
 		return -EIO;
 	}

 	if (t->enabled) {
 		err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
 						(ABX8XX_IRQ_IM_1_4 |
 						 ABX8XX_IRQ_AIE));
 		if (err)
 			return err;
 	}

 	return 0;
 }

 static int abx80x_rtc_set_autocalibration(struct device *dev,
 					  int autocalibration)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int retval, flags = 0;

 	if ((autocalibration != 0) && (autocalibration != 1024) &&
 	    (autocalibration != 512)) {
 		dev_err(dev, "autocalibration value outside permitted range\n");
 		return -EINVAL;
 	}

 	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
 	if (flags < 0)
 		return flags;

 	if (autocalibration == 0) {
 		flags &= ~(ABX8XX_OSC_ACAL_512 | ABX8XX_OSC_ACAL_1024);
 	} else if (autocalibration == 1024) {
 		/* 1024 autocalibration is 0x10 */
 		flags |= ABX8XX_OSC_ACAL_1024;
 		flags &= ~(ABX8XX_OSC_ACAL_512);
 	} else {
 		/* 512 autocalibration is 0x11 */
 		flags |= (ABX8XX_OSC_ACAL_1024 | ABX8XX_OSC_ACAL_512);
 	}

 	/* Unlock write access to Oscillator Control Register */
 	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
 					   ABX8XX_CFG_KEY_OSC);
 	if (retval < 0) {
 		dev_err(dev, "Failed to write CONFIG_KEY register\n");
 		return retval;
 	}

 	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);

 	return retval;
 }

 static int abx80x_rtc_get_autocalibration(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int flags = 0, autocalibration;

 	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
 	if (flags < 0)
 		return flags;

 	if (flags & ABX8XX_OSC_ACAL_512)
 		autocalibration = 512;
 	else if (flags & ABX8XX_OSC_ACAL_1024)
 		autocalibration = 1024;
 	else
 		autocalibration = 0;

 	return autocalibration;
 }

 static ssize_t autocalibration_store(struct device *dev,
 				     struct device_attribute *attr,
 				     const char *buf, size_t count)
 {
 	int retval;
 	unsigned long autocalibration = 0;

 	retval = kstrtoul(buf, 10, &autocalibration);
 	if (retval < 0) {
 		dev_err(dev, "Failed to store RTC autocalibration attribute\n");
 		return -EINVAL;
 	}

 	retval = abx80x_rtc_set_autocalibration(dev, autocalibration);

 	return retval ? retval : count;
 }

 static ssize_t autocalibration_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	int autocalibration = 0;

 	autocalibration = abx80x_rtc_get_autocalibration(dev);
 	if (autocalibration < 0) {
 		dev_err(dev, "Failed to read RTC autocalibration\n");
 		sprintf(buf, "0\n");
 		return autocalibration;
 	}

 	return sprintf(buf, "%d\n", autocalibration);
 }

 static DEVICE_ATTR_RW(autocalibration);

 static ssize_t oscillator_store(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int retval, flags, rc_mode = 0;

 	if (strncmp(buf, "rc", 2) == 0) {
 		rc_mode = 1;
 	} else if (strncmp(buf, "xtal", 4) == 0) {
 		rc_mode = 0;
 	} else {
 		dev_err(dev, "Oscillator selection value outside permitted ones\n");
 		return -EINVAL;
 	}

 	flags =  i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
 	if (flags < 0)
 		return flags;

 	if (rc_mode == 0)
 		flags &= ~(ABX8XX_OSC_OSEL);
 	else
 		flags |= (ABX8XX_OSC_OSEL);

 	/* Unlock write access on Oscillator Control register */
 	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
 					   ABX8XX_CFG_KEY_OSC);
 	if (retval < 0) {
 		dev_err(dev, "Failed to write CONFIG_KEY register\n");
 		return retval;
 	}

 	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);
 	if (retval < 0) {
 		dev_err(dev, "Failed to write Oscillator Control register\n");
 		return retval;
 	}

 	return retval ? retval : count;
 }

 static ssize_t oscillator_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
 	int rc_mode = 0;
 	struct i2c_client *client = to_i2c_client(dev);

 	rc_mode = abx80x_is_rc_mode(client);

 	if (rc_mode < 0) {
 		dev_err(dev, "Failed to read RTC oscillator selection\n");
 		sprintf(buf, "\n");
 		return rc_mode;
 	}

 	if (rc_mode)
 		return sprintf(buf, "rc\n");
 	else
 		return sprintf(buf, "xtal\n");
 }

 static DEVICE_ATTR_RW(oscillator);

 static struct attribute *rtc_calib_attrs[] = {
 	&dev_attr_autocalibration.attr,
 	&dev_attr_oscillator.attr,
 	NULL,
 };

 static const struct attribute_group rtc_calib_attr_group = {
 	.attrs		= rtc_calib_attrs,
 };

 static int abx80x_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int err;

 	if (enabled)
 		err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
 						(ABX8XX_IRQ_IM_1_4 |
 						 ABX8XX_IRQ_AIE));
 	else
 		err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
 						ABX8XX_IRQ_IM_1_4);
 	return err;
 }

 static const struct rtc_class_ops abx80x_rtc_ops = {
 	.read_time	= abx80x_rtc_read_time,
 	.set_time	= abx80x_rtc_set_time,
 	.read_alarm	= abx80x_read_alarm,
 	.set_alarm	= abx80x_set_alarm,
 	.alarm_irq_enable = abx80x_alarm_irq_enable,
 };

 static int abx80x_dt_trickle_cfg(struct device_node *np)
 {
 	const char *diode;
 	int trickle_cfg = 0;
 	int i, ret;
 	u32 tmp;

 	ret = of_property_read_string(np, "abracon,tc-diode", &diode);
 	if (ret)
 		return ret;

 	if (!strcmp(diode, "standard"))
 		trickle_cfg |= ABX8XX_TRICKLE_STANDARD_DIODE;
 	else if (!strcmp(diode, "schottky"))
 		trickle_cfg |= ABX8XX_TRICKLE_SCHOTTKY_DIODE;
 	else
 		return -EINVAL;

 	ret = of_property_read_u32(np, "abracon,tc-resistor", &tmp);
 	if (ret)
 		return ret;

 	for (i = 0; i < sizeof(trickle_resistors); i++)
 		if (trickle_resistors[i] == tmp)
 			break;

 	if (i == sizeof(trickle_resistors))
 		return -EINVAL;

 	return (trickle_cfg | i);
 }

 static void rtc_calib_remove_sysfs_group(void *_dev)
 {
 	struct device *dev = _dev;

 	sysfs_remove_group(&dev->kobj, &rtc_calib_attr_group);
 }

 #ifdef CONFIG_WATCHDOG

 static inline u8 timeout_bits(unsigned int timeout)
 {
 	return ((timeout << ABX8XX_WDT_BMB_SHIFT) & ABX8XX_WDT_BMB_MASK) |
 		 ABX8XX_WDT_WRB_1HZ;
 }

 static int __abx80x_wdog_set_timeout(struct watchdog_device *wdog,
 				     unsigned int timeout)
 {
 	struct abx80x_priv *priv = watchdog_get_drvdata(wdog);
 	u8 val = ABX8XX_WDT_WDS | timeout_bits(timeout);

 	/*
 	 * Writing any timeout to the WDT register resets the watchdog timer.
 	 * Writing 0 disables it.
 	 */
 	return i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_WDT, val);
 }

 static int abx80x_wdog_set_timeout(struct watchdog_device *wdog,
 				   unsigned int new_timeout)
 {
 	int err = 0;

 	if (watchdog_hw_running(wdog))
 		err = __abx80x_wdog_set_timeout(wdog, new_timeout);

 	if (err == 0)
 		wdog->timeout = new_timeout;

 	return err;
 }

 static int abx80x_wdog_ping(struct watchdog_device *wdog)
 {
 	return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
 }

 static int abx80x_wdog_start(struct watchdog_device *wdog)
 {
 	return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
 }

 static int abx80x_wdog_stop(struct watchdog_device *wdog)
 {
 	return __abx80x_wdog_set_timeout(wdog, 0);
 }

 static const struct watchdog_info abx80x_wdog_info = {
 	.identity = "abx80x watchdog",
 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 };

 static const struct watchdog_ops abx80x_wdog_ops = {
 	.owner = THIS_MODULE,
 	.start = abx80x_wdog_start,
 	.stop = abx80x_wdog_stop,
 	.ping = abx80x_wdog_ping,
 	.set_timeout = abx80x_wdog_set_timeout,
 };

 static int abx80x_setup_watchdog(struct abx80x_priv *priv)
 {
 	priv->wdog.parent = &priv->client->dev;
 	priv->wdog.ops = &abx80x_wdog_ops;
 	priv->wdog.info = &abx80x_wdog_info;
 	priv->wdog.min_timeout = 1;
 	priv->wdog.max_timeout = ABX8XX_WDT_MAX_TIME;
 	priv->wdog.timeout = ABX8XX_WDT_MAX_TIME;

 	watchdog_set_drvdata(&priv->wdog, priv);

 	return devm_watchdog_register_device(&priv->client->dev, &priv->wdog);
 }
 #else
 static int abx80x_setup_watchdog(struct abx80x_priv *priv)
 {
 	return 0;
 }
 #endif

 static int abx80x_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct device_node *np = client->dev.of_node;
 	struct abx80x_priv *priv;
 	int i, data, err, trickle_cfg = -EINVAL;
 	char buf[7];
 	unsigned int part = id->driver_data;
 	unsigned int partnumber;
 	unsigned int majrev, minrev;
 	unsigned int lot;
 	unsigned int wafer;
 	unsigned int uid;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;

 	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ID0,
 					    sizeof(buf), buf);
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to read partnumber\n");
 		return -EIO;
 	}

 	partnumber = (buf[0] << 8) | buf[1];
 	majrev = buf[2] >> 3;
 	minrev = buf[2] & 0x7;
 	lot = ((buf[4] & 0x80) << 2) | ((buf[6] & 0x80) << 1) | buf[3];
 	uid = ((buf[4] & 0x7f) << 8) | buf[5];
 	wafer = (buf[6] & 0x7c) >> 2;
 	dev_info(&client->dev, "model %04x, revision %u.%u, lot %x, wafer %x, uid %x\n",
 		 partnumber, majrev, minrev, lot, wafer, uid);

 	data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL1);
 	if (data < 0) {
 		dev_err(&client->dev, "Unable to read control register\n");
 		return -EIO;
 	}

 	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL1,
 					((data & ~(ABX8XX_CTRL_12_24 |
 						   ABX8XX_CTRL_ARST)) |
 					 ABX8XX_CTRL_WRITE));
 	if (err < 0) {
 		dev_err(&client->dev, "Unable to write control register\n");
 		return -EIO;
 	}

 	/* part autodetection */
 	if (part == ABX80X) {
 		for (i = 0; abx80x_caps[i].pn; i++)
 			if (partnumber == abx80x_caps[i].pn)
 				break;
 		if (abx80x_caps[i].pn == 0) {
 			dev_err(&client->dev, "Unknown part: %04x\n",
 				partnumber);
 			return -EINVAL;
 		}
 		part = i;
 	}

 	if (partnumber != abx80x_caps[part].pn) {
 		dev_err(&client->dev, "partnumber mismatch %04x != %04x\n",
 			partnumber, abx80x_caps[part].pn);
 		return -EINVAL;
 	}

 	if (np && abx80x_caps[part].has_tc)
 		trickle_cfg = abx80x_dt_trickle_cfg(np);

 	if (trickle_cfg > 0) {
 		dev_info(&client->dev, "Enabling trickle charger: %02x\n",
 			 trickle_cfg);
 		abx80x_enable_trickle_charger(client, trickle_cfg);
 	}

 	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CD_TIMER_CTL,
 					BIT(2));
 	if (err)
 		return err;

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

 	priv->rtc = devm_rtc_allocate_device(&client->dev);
 	if (IS_ERR(priv->rtc))
 		return PTR_ERR(priv->rtc);

 	priv->rtc->ops = &abx80x_rtc_ops;
 	priv->client = client;

 	i2c_set_clientdata(client, priv);

 	if (abx80x_caps[part].has_wdog) {
 		err = abx80x_setup_watchdog(priv);
 		if (err)
 			return err;
 	}

 	if (client->irq > 0) {
 		dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
 		err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
 						abx80x_handle_irq,
 						IRQF_SHARED | IRQF_ONESHOT,
 						"abx8xx",
 						client);
 		if (err) {
 			dev_err(&client->dev, "unable to request IRQ, alarms disabled\n");
 			client->irq = 0;
 		}
 	}

 	/* Export sysfs entries */
 	err = sysfs_create_group(&(&client->dev)->kobj, &rtc_calib_attr_group);
 	if (err) {
 		dev_err(&client->dev, "Failed to create sysfs group: %d\n",
 			err);
 		return err;
 	}

 	err = devm_add_action_or_reset(&client->dev,
 				       rtc_calib_remove_sysfs_group,
 				       &client->dev);
 	if (err) {
 		dev_err(&client->dev,
 			"Failed to add sysfs cleanup action: %d\n",
 			err);
 		return err;
 	}

 	err = rtc_register_device(priv->rtc);

 	return err;
 }

 static int abx80x_remove(struct i2c_client *client)
 {
 	return 0;
 }

 static const struct i2c_device_id abx80x_id[] = {
 	{ "abx80x", ABX80X },
 	{ "ab0801", AB0801 },
 	{ "ab0803", AB0803 },
 	{ "ab0804", AB0804 },
 	{ "ab0805", AB0805 },
 	{ "ab1801", AB1801 },
 	{ "ab1803", AB1803 },
 	{ "ab1804", AB1804 },
 	{ "ab1805", AB1805 },
 	{ "rv1805", AB1805 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, abx80x_id);

 static struct i2c_driver abx80x_driver = {
 	.driver		= {
 		.name	= "rtc-abx80x",
 	},
 	.probe		= abx80x_probe,
 	.remove		= abx80x_remove,
 	.id_table	= abx80x_id,
 };

 module_i2c_driver(abx80x_driver);

 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
 MODULE_DESCRIPTION("Abracon ABX80X RTC driver");
 MODULE_LICENSE("GPL v2");
	/*
	* A driver for the I2C members of the Abracon AB x8xx RTC family,
	* and compatible: AB 1805 and AB 0805
	*
	* Copyright 2014-2015 Macq S.A.
	*
	* Author: Philippe De Muyter <phdm@macqel.be>
	* Author: Alexandre Belloni <alexandre.belloni@free-electrons.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	*/

	#include <linux/bcd.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/watchdog.h>

	#define ABX8XX_REG_HTH 0x00
	#define ABX8XX_REG_SC 0x01
	#define ABX8XX_REG_MN 0x02
	#define ABX8XX_REG_HR 0x03
	#define ABX8XX_REG_DA 0x04
	#define ABX8XX_REG_MO 0x05
	#define ABX8XX_REG_YR 0x06
	#define ABX8XX_REG_WD 0x07

	#define ABX8XX_REG_AHTH 0x08
	#define ABX8XX_REG_ASC 0x09
	#define ABX8XX_REG_AMN 0x0a
	#define ABX8XX_REG_AHR 0x0b
	#define ABX8XX_REG_ADA 0x0c
	#define ABX8XX_REG_AMO 0x0d
	#define ABX8XX_REG_AWD 0x0e

	#define ABX8XX_REG_STATUS 0x0f
	#define ABX8XX_STATUS_AF BIT(2)
	#define ABX8XX_STATUS_WDT BIT(6)

	#define ABX8XX_REG_CTRL1 0x10
	#define ABX8XX_CTRL_WRITE BIT(0)
	#define ABX8XX_CTRL_ARST BIT(2)
	#define ABX8XX_CTRL_12_24 BIT(6)

	#define ABX8XX_REG_IRQ 0x12
	#define ABX8XX_IRQ_AIE BIT(2)
	#define ABX8XX_IRQ_IM_1_4 (0x3 << 5)

	#define ABX8XX_REG_CD_TIMER_CTL 0x18

	#define ABX8XX_REG_OSC 0x1c
	#define ABX8XX_OSC_FOS BIT(3)
	#define ABX8XX_OSC_BOS BIT(4)
	#define ABX8XX_OSC_ACAL_512 BIT(5)
	#define ABX8XX_OSC_ACAL_1024 BIT(6)

	#define ABX8XX_OSC_OSEL BIT(7)

	#define ABX8XX_REG_OSS 0x1d
	#define ABX8XX_OSS_OF BIT(1)
	#define ABX8XX_OSS_OMODE BIT(4)

	#define ABX8XX_REG_WDT 0x1b
	#define ABX8XX_WDT_WDS BIT(7)
	#define ABX8XX_WDT_BMB_MASK 0x7c
	#define ABX8XX_WDT_BMB_SHIFT 2
	#define ABX8XX_WDT_MAX_TIME (ABX8XX_WDT_BMB_MASK >> ABX8XX_WDT_BMB_SHIFT)
	#define ABX8XX_WDT_WRB_MASK 0x03
	#define ABX8XX_WDT_WRB_1HZ 0x02

	#define ABX8XX_REG_CFG_KEY 0x1f
	#define ABX8XX_CFG_KEY_OSC 0xa1
	#define ABX8XX_CFG_KEY_MISC 0x9d

	#define ABX8XX_REG_ID0 0x28

	#define ABX8XX_REG_TRICKLE 0x20
	#define ABX8XX_TRICKLE_CHARGE_ENABLE 0xa0
	#define ABX8XX_TRICKLE_STANDARD_DIODE 0x8
	#define ABX8XX_TRICKLE_SCHOTTKY_DIODE 0x4

	static u8 trickle_resistors[] = {0, 3, 6, 11};

	enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
	AB1801, AB1803, AB1804, AB1805, ABX80X};

	struct abx80x_cap {
	u16 pn;
	bool has_tc;
	bool has_wdog;
	};

	static struct abx80x_cap abx80x_caps[] = {
	[AB0801] = {.pn = 0x0801},
	[AB0803] = {.pn = 0x0803},
	[AB0804] = {.pn = 0x0804, .has_tc = true, .has_wdog = true},
	[AB0805] = {.pn = 0x0805, .has_tc = true, .has_wdog = true},
	[AB1801] = {.pn = 0x1801},
	[AB1803] = {.pn = 0x1803},
	[AB1804] = {.pn = 0x1804, .has_tc = true, .has_wdog = true},
	[AB1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
	[ABX80X] = {.pn = 0}
	};

	struct abx80x_priv {
	struct rtc_device *rtc;
	struct i2c_client *client;
	struct watchdog_device wdog;
	};

	static int abx80x_is_rc_mode(struct i2c_client *client)
	{
	int flags = 0;

	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
	if (flags < 0) {
	dev_err(&client->dev,
	"Failed to read autocalibration attribute\n");
	return flags;
	}

	return (flags & ABX8XX_OSS_OMODE) ? 1 : 0;
	}

	static int abx80x_enable_trickle_charger(struct i2c_client *client,
	u8 trickle_cfg)
	{
	int err;

	/*
	* Write the configuration key register to enable access to the Trickle
	* register
	*/
	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
	ABX8XX_CFG_KEY_MISC);
	if (err < 0) {
	dev_err(&client->dev, "Unable to write configuration key\n");
	return -EIO;
	}

	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_TRICKLE,
	ABX8XX_TRICKLE_CHARGE_ENABLE \|
	trickle_cfg);
	if (err < 0) {
	dev_err(&client->dev, "Unable to write trickle register\n");
	return -EIO;
	}

	return 0;
	}

	static int abx80x_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned char buf[8];
	int err, flags, rc_mode = 0;

	/* Read the Oscillator Failure only in XT mode */
	rc_mode = abx80x_is_rc_mode(client);
	if (rc_mode < 0)
	return rc_mode;

	if (!rc_mode) {
	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
	if (flags < 0)
	return flags;

	if (flags & ABX8XX_OSS_OF) {
	dev_err(dev, "Oscillator failure, data is invalid.\n");
	return -EINVAL;
	}
	}

	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_HTH,
	sizeof(buf), buf);
	if (err < 0) {
	dev_err(&client->dev, "Unable to read date\n");
	return -EIO;
	}

	tm->tm_sec = bcd2bin(buf[ABX8XX_REG_SC] & 0x7F);
	tm->tm_min = bcd2bin(buf[ABX8XX_REG_MN] & 0x7F);
	tm->tm_hour = bcd2bin(buf[ABX8XX_REG_HR] & 0x3F);
	tm->tm_wday = buf[ABX8XX_REG_WD] & 0x7;
	tm->tm_mday = bcd2bin(buf[ABX8XX_REG_DA] & 0x3F);
	tm->tm_mon = bcd2bin(buf[ABX8XX_REG_MO] & 0x1F) - 1;
	tm->tm_year = bcd2bin(buf[ABX8XX_REG_YR]) + 100;

	return 0;
	}

	static int abx80x_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned char buf[8];
	int err, flags;

	if (tm->tm_year < 100)
	return -EINVAL;

	buf[ABX8XX_REG_HTH] = 0;
	buf[ABX8XX_REG_SC] = bin2bcd(tm->tm_sec);
	buf[ABX8XX_REG_MN] = bin2bcd(tm->tm_min);
	buf[ABX8XX_REG_HR] = bin2bcd(tm->tm_hour);
	buf[ABX8XX_REG_DA] = bin2bcd(tm->tm_mday);
	buf[ABX8XX_REG_MO] = bin2bcd(tm->tm_mon + 1);
	buf[ABX8XX_REG_YR] = bin2bcd(tm->tm_year - 100);
	buf[ABX8XX_REG_WD] = tm->tm_wday;

	err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_HTH,
	sizeof(buf), buf);
	if (err < 0) {
	dev_err(&client->dev, "Unable to write to date registers\n");
	return -EIO;
	}

	/* Clear the OF bit of Oscillator Status Register */
	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSS);
	if (flags < 0)
	return flags;

	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSS,
	flags & ~ABX8XX_OSS_OF);
	if (err < 0) {
	dev_err(&client->dev, "Unable to write oscillator status register\n");
	return err;
	}

	return 0;
	}

	static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
	{
	struct i2c_client *client = dev_id;
	struct abx80x_priv *priv = i2c_get_clientdata(client);
	struct rtc_device *rtc = priv->rtc;
	int status;

	status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
	if (status < 0)
	return IRQ_NONE;

	if (status & ABX8XX_STATUS_AF)
	rtc_update_irq(rtc, 1, RTC_AF \| RTC_IRQF);

	/*
	* It is unclear if we'll get an interrupt before the external
	* reset kicks in.
	*/
	if (status & ABX8XX_STATUS_WDT)
	dev_alert(&client->dev, "watchdog timeout interrupt.\n");

	i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);

	return IRQ_HANDLED;
	}

	static int abx80x_read_alarm(struct device dev, struct rtc_wkalrm t)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned char buf[7];

	int irq_mask, err;

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

	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ASC,
	sizeof(buf), buf);
	if (err)
	return err;

	irq_mask = i2c_smbus_read_byte_data(client, ABX8XX_REG_IRQ);
	if (irq_mask < 0)
	return irq_mask;

	t->time.tm_sec = bcd2bin(buf[0] & 0x7F);
	t->time.tm_min = bcd2bin(buf[1] & 0x7F);
	t->time.tm_hour = bcd2bin(buf[2] & 0x3F);
	t->time.tm_mday = bcd2bin(buf[3] & 0x3F);
	t->time.tm_mon = bcd2bin(buf[4] & 0x1F) - 1;
	t->time.tm_wday = buf[5] & 0x7;

	t->enabled = !!(irq_mask & ABX8XX_IRQ_AIE);
	t->pending = (buf[6] & ABX8XX_STATUS_AF) && t->enabled;

	return err;
	}

	static int abx80x_set_alarm(struct device dev, struct rtc_wkalrm t)
	{
	struct i2c_client *client = to_i2c_client(dev);
	u8 alarm[6];
	int err;

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

	alarm[0] = 0x0;
	alarm[1] = bin2bcd(t->time.tm_sec);
	alarm[2] = bin2bcd(t->time.tm_min);
	alarm[3] = bin2bcd(t->time.tm_hour);
	alarm[4] = bin2bcd(t->time.tm_mday);
	alarm[5] = bin2bcd(t->time.tm_mon + 1);

	err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_AHTH,
	sizeof(alarm), alarm);
	if (err < 0) {
	dev_err(&client->dev, "Unable to write alarm registers\n");
	return -EIO;
	}

	if (t->enabled) {
	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
	(ABX8XX_IRQ_IM_1_4 \|
	ABX8XX_IRQ_AIE));
	if (err)
	return err;
	}

	return 0;
	}

	static int abx80x_rtc_set_autocalibration(struct device *dev,
	int autocalibration)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int retval, flags = 0;

	if ((autocalibration != 0) && (autocalibration != 1024) &&
	(autocalibration != 512)) {
	dev_err(dev, "autocalibration value outside permitted range\n");
	return -EINVAL;
	}

	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
	if (flags < 0)
	return flags;

	if (autocalibration == 0) {
	flags &= ~(ABX8XX_OSC_ACAL_512 \| ABX8XX_OSC_ACAL_1024);
	} else if (autocalibration == 1024) {
	/* 1024 autocalibration is 0x10 */
	flags \|= ABX8XX_OSC_ACAL_1024;
	flags &= ~(ABX8XX_OSC_ACAL_512);
	} else {
	/* 512 autocalibration is 0x11 */
	flags \|= (ABX8XX_OSC_ACAL_1024 \| ABX8XX_OSC_ACAL_512);
	}

	/* Unlock write access to Oscillator Control Register */
	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
	ABX8XX_CFG_KEY_OSC);
	if (retval < 0) {
	dev_err(dev, "Failed to write CONFIG_KEY register\n");
	return retval;
	}

	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);

	return retval;
	}

	static int abx80x_rtc_get_autocalibration(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int flags = 0, autocalibration;

	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
	if (flags < 0)
	return flags;

	if (flags & ABX8XX_OSC_ACAL_512)
	autocalibration = 512;
	else if (flags & ABX8XX_OSC_ACAL_1024)
	autocalibration = 1024;
	else
	autocalibration = 0;

	return autocalibration;
	}

	static ssize_t autocalibration_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	int retval;
	unsigned long autocalibration = 0;

	retval = kstrtoul(buf, 10, &autocalibration);
	if (retval < 0) {
	dev_err(dev, "Failed to store RTC autocalibration attribute\n");
	return -EINVAL;
	}

	retval = abx80x_rtc_set_autocalibration(dev, autocalibration);

	return retval ? retval : count;
	}

	static ssize_t autocalibration_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	int autocalibration = 0;

	autocalibration = abx80x_rtc_get_autocalibration(dev);
	if (autocalibration < 0) {
	dev_err(dev, "Failed to read RTC autocalibration\n");
	sprintf(buf, "0\n");
	return autocalibration;
	}

	return sprintf(buf, "%d\n", autocalibration);
	}

	static DEVICE_ATTR_RW(autocalibration);

	static ssize_t oscillator_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int retval, flags, rc_mode = 0;

	if (strncmp(buf, "rc", 2) == 0) {
	rc_mode = 1;
	} else if (strncmp(buf, "xtal", 4) == 0) {
	rc_mode = 0;
	} else {
	dev_err(dev, "Oscillator selection value outside permitted ones\n");
	return -EINVAL;
	}

	flags = i2c_smbus_read_byte_data(client, ABX8XX_REG_OSC);
	if (flags < 0)
	return flags;

	if (rc_mode == 0)
	flags &= ~(ABX8XX_OSC_OSEL);
	else
	flags \|= (ABX8XX_OSC_OSEL);

	/* Unlock write access on Oscillator Control register */
	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
	ABX8XX_CFG_KEY_OSC);
	if (retval < 0) {
	dev_err(dev, "Failed to write CONFIG_KEY register\n");
	return retval;
	}

	retval = i2c_smbus_write_byte_data(client, ABX8XX_REG_OSC, flags);
	if (retval < 0) {
	dev_err(dev, "Failed to write Oscillator Control register\n");
	return retval;
	}

	return retval ? retval : count;
	}

	static ssize_t oscillator_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	int rc_mode = 0;
	struct i2c_client *client = to_i2c_client(dev);

	rc_mode = abx80x_is_rc_mode(client);

	if (rc_mode < 0) {
	dev_err(dev, "Failed to read RTC oscillator selection\n");
	sprintf(buf, "\n");
	return rc_mode;
	}

	if (rc_mode)
	return sprintf(buf, "rc\n");
	else
	return sprintf(buf, "xtal\n");
	}

	static DEVICE_ATTR_RW(oscillator);

	static struct attribute *rtc_calib_attrs[] = {
	&dev_attr_autocalibration.attr,
	&dev_attr_oscillator.attr,
	NULL,
	};

	static const struct attribute_group rtc_calib_attr_group = {
	.attrs = rtc_calib_attrs,
	};

	static int abx80x_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int err;

	if (enabled)
	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
	(ABX8XX_IRQ_IM_1_4 \|
	ABX8XX_IRQ_AIE));
	else
	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_IRQ,
	ABX8XX_IRQ_IM_1_4);
	return err;
	}

	static const struct rtc_class_ops abx80x_rtc_ops = {
	.read_time = abx80x_rtc_read_time,
	.set_time = abx80x_rtc_set_time,
	.read_alarm = abx80x_read_alarm,
	.set_alarm = abx80x_set_alarm,
	.alarm_irq_enable = abx80x_alarm_irq_enable,
	};

	static int abx80x_dt_trickle_cfg(struct device_node *np)
	{
	const char *diode;
	int trickle_cfg = 0;
	int i, ret;
	u32 tmp;

	ret = of_property_read_string(np, "abracon,tc-diode", &diode);
	if (ret)
	return ret;

	if (!strcmp(diode, "standard"))
	trickle_cfg \|= ABX8XX_TRICKLE_STANDARD_DIODE;
	else if (!strcmp(diode, "schottky"))
	trickle_cfg \|= ABX8XX_TRICKLE_SCHOTTKY_DIODE;
	else
	return -EINVAL;

	ret = of_property_read_u32(np, "abracon,tc-resistor", &tmp);
	if (ret)
	return ret;

	for (i = 0; i < sizeof(trickle_resistors); i++)
	if (trickle_resistors[i] == tmp)
	break;

	if (i == sizeof(trickle_resistors))
	return -EINVAL;

	return (trickle_cfg \| i);
	}

	static void rtc_calib_remove_sysfs_group(void *_dev)
	{
	struct device *dev = _dev;

	sysfs_remove_group(&dev->kobj, &rtc_calib_attr_group);
	}

	#ifdef CONFIG_WATCHDOG

	static inline u8 timeout_bits(unsigned int timeout)
	{
	return ((timeout << ABX8XX_WDT_BMB_SHIFT) & ABX8XX_WDT_BMB_MASK) \|
	ABX8XX_WDT_WRB_1HZ;
	}

	static int __abx80x_wdog_set_timeout(struct watchdog_device *wdog,
	unsigned int timeout)
	{
	struct abx80x_priv *priv = watchdog_get_drvdata(wdog);
	u8 val = ABX8XX_WDT_WDS \| timeout_bits(timeout);

	/*
	* Writing any timeout to the WDT register resets the watchdog timer.
	* Writing 0 disables it.
	*/
	return i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_WDT, val);
	}

	static int abx80x_wdog_set_timeout(struct watchdog_device *wdog,
	unsigned int new_timeout)
	{
	int err = 0;

	if (watchdog_hw_running(wdog))
	err = __abx80x_wdog_set_timeout(wdog, new_timeout);

	if (err == 0)
	wdog->timeout = new_timeout;

	return err;
	}

	static int abx80x_wdog_ping(struct watchdog_device *wdog)
	{
	return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
	}

	static int abx80x_wdog_start(struct watchdog_device *wdog)
	{
	return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
	}

	static int abx80x_wdog_stop(struct watchdog_device *wdog)
	{
	return __abx80x_wdog_set_timeout(wdog, 0);
	}

	static const struct watchdog_info abx80x_wdog_info = {
	.identity = "abx80x watchdog",
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE,
	};

	static const struct watchdog_ops abx80x_wdog_ops = {
	.owner = THIS_MODULE,
	.start = abx80x_wdog_start,
	.stop = abx80x_wdog_stop,
	.ping = abx80x_wdog_ping,
	.set_timeout = abx80x_wdog_set_timeout,
	};

	static int abx80x_setup_watchdog(struct abx80x_priv *priv)
	{
	priv->wdog.parent = &priv->client->dev;
	priv->wdog.ops = &abx80x_wdog_ops;
	priv->wdog.info = &abx80x_wdog_info;
	priv->wdog.min_timeout = 1;
	priv->wdog.max_timeout = ABX8XX_WDT_MAX_TIME;
	priv->wdog.timeout = ABX8XX_WDT_MAX_TIME;

	watchdog_set_drvdata(&priv->wdog, priv);

	return devm_watchdog_register_device(&priv->client->dev, &priv->wdog);
	}
	#else
	static int abx80x_setup_watchdog(struct abx80x_priv *priv)
	{
	return 0;
	}
	#endif

	static int abx80x_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device_node *np = client->dev.of_node;
	struct abx80x_priv *priv;
	int i, data, err, trickle_cfg = -EINVAL;
	char buf[7];
	unsigned int part = id->driver_data;
	unsigned int partnumber;
	unsigned int majrev, minrev;
	unsigned int lot;
	unsigned int wafer;
	unsigned int uid;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -ENODEV;

	err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ID0,
	sizeof(buf), buf);
	if (err < 0) {
	dev_err(&client->dev, "Unable to read partnumber\n");
	return -EIO;
	}

	partnumber = (buf[0] << 8) \| buf[1];
	majrev = buf[2] >> 3;
	minrev = buf[2] & 0x7;
	lot = ((buf[4] & 0x80) << 2) \| ((buf[6] & 0x80) << 1) \| buf[3];
	uid = ((buf[4] & 0x7f) << 8) \| buf[5];
	wafer = (buf[6] & 0x7c) >> 2;
	dev_info(&client->dev, "model %04x, revision %u.%u, lot %x, wafer %x, uid %x\n",
	partnumber, majrev, minrev, lot, wafer, uid);

	data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL1);
	if (data < 0) {
	dev_err(&client->dev, "Unable to read control register\n");
	return -EIO;
	}

	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL1,
	((data & ~(ABX8XX_CTRL_12_24 \|
	ABX8XX_CTRL_ARST)) \|
	ABX8XX_CTRL_WRITE));
	if (err < 0) {
	dev_err(&client->dev, "Unable to write control register\n");
	return -EIO;
	}

	/* part autodetection */
	if (part == ABX80X) {
	for (i = 0; abx80x_caps[i].pn; i++)
	if (partnumber == abx80x_caps[i].pn)
	break;
	if (abx80x_caps[i].pn == 0) {
	dev_err(&client->dev, "Unknown part: %04x\n",
	partnumber);
	return -EINVAL;
	}
	part = i;
	}

	if (partnumber != abx80x_caps[part].pn) {
	dev_err(&client->dev, "partnumber mismatch %04x != %04x\n",
	partnumber, abx80x_caps[part].pn);
	return -EINVAL;
	}

	if (np && abx80x_caps[part].has_tc)
	trickle_cfg = abx80x_dt_trickle_cfg(np);

	if (trickle_cfg > 0) {
	dev_info(&client->dev, "Enabling trickle charger: %02x\n",
	trickle_cfg);
	abx80x_enable_trickle_charger(client, trickle_cfg);
	}

	err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CD_TIMER_CTL,
	BIT(2));
	if (err)
	return err;

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

	priv->rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(priv->rtc))
	return PTR_ERR(priv->rtc);

	priv->rtc->ops = &abx80x_rtc_ops;
	priv->client = client;

	i2c_set_clientdata(client, priv);

	if (abx80x_caps[part].has_wdog) {
	err = abx80x_setup_watchdog(priv);
	if (err)
	return err;
	}

	if (client->irq > 0) {
	dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
	abx80x_handle_irq,
	IRQF_SHARED \| IRQF_ONESHOT,
	"abx8xx",
	client);
	if (err) {
	dev_err(&client->dev, "unable to request IRQ, alarms disabled\n");
	client->irq = 0;
	}
	}

	/* Export sysfs entries */
	err = sysfs_create_group(&(&client->dev)->kobj, &rtc_calib_attr_group);
	if (err) {
	dev_err(&client->dev, "Failed to create sysfs group: %d\n",
	err);
	return err;
	}

	err = devm_add_action_or_reset(&client->dev,
	rtc_calib_remove_sysfs_group,
	&client->dev);
	if (err) {
	dev_err(&client->dev,
	"Failed to add sysfs cleanup action: %d\n",
	err);
	return err;
	}

	err = rtc_register_device(priv->rtc);

	return err;
	}

	static int abx80x_remove(struct i2c_client *client)
	{
	return 0;
	}

	static const struct i2c_device_id abx80x_id[] = {
	{ "abx80x", ABX80X },
	{ "ab0801", AB0801 },
	{ "ab0803", AB0803 },
	{ "ab0804", AB0804 },
	{ "ab0805", AB0805 },
	{ "ab1801", AB1801 },
	{ "ab1803", AB1803 },
	{ "ab1804", AB1804 },
	{ "ab1805", AB1805 },
	{ "rv1805", AB1805 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, abx80x_id);

	static struct i2c_driver abx80x_driver = {
	.driver = {
	.name = "rtc-abx80x",
	},
	.probe = abx80x_probe,
	.remove = abx80x_remove,
	.id_table = abx80x_id,
	};

	module_i2c_driver(abx80x_driver);

	MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
	MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
	MODULE_DESCRIPTION("Abracon ABX80X RTC driver");
	MODULE_LICENSE("GPL v2");