drivers/rtc/rtc-isl12022.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * An I2C driver for the Intersil ISL 12022
  *
  * Author: Roman Fietze <roman.fietze@telemotive.de>
  *
  * Based on the Philips PCF8563 RTC
  * by Alessandro Zummo <a.zummo@towertech.it>.
  */

 #include <linux/bcd.h>
 #include <linux/bitfield.h>
 #include <linux/clk-provider.h>
 #include <linux/err.h>
 #include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 #include <linux/rtc.h>
 #include <linux/slab.h>

 #include <asm/byteorder.h>

 /* ISL register offsets */
 #define ISL12022_REG_SC		0x00
 #define ISL12022_REG_MN		0x01
 #define ISL12022_REG_HR		0x02
 #define ISL12022_REG_DT		0x03
 #define ISL12022_REG_MO		0x04
 #define ISL12022_REG_YR		0x05
 #define ISL12022_REG_DW		0x06

 #define ISL12022_REG_SR		0x07
 #define ISL12022_REG_INT	0x08

 #define ISL12022_REG_PWR_VBAT	0x0a

 #define ISL12022_REG_BETA	0x0d
 #define ISL12022_REG_TEMP_L	0x28

 /* ISL register bits */
 #define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */

 #define ISL12022_SR_LBAT85	(1 << 2)
 #define ISL12022_SR_LBAT75	(1 << 1)

 #define ISL12022_INT_WRTC	(1 << 6)
 #define ISL12022_INT_FO_MASK	GENMASK(3, 0)
 #define ISL12022_INT_FO_OFF	0x0
 #define ISL12022_INT_FO_32K	0x1

 #define ISL12022_REG_VB85_MASK	GENMASK(5, 3)
 #define ISL12022_REG_VB75_MASK	GENMASK(2, 0)

 #define ISL12022_BETA_TSE	(1 << 7)

 static umode_t isl12022_hwmon_is_visible(const void *data,
 					 enum hwmon_sensor_types type,
 					 u32 attr, int channel)
 {
 	if (type == hwmon_temp && attr == hwmon_temp_input)
 		return 0444;

 	return 0;
 }

 /*
  * A user-initiated temperature conversion is not started by this function,
  * so the temperature is updated once every ~60 seconds.
  */
 static int isl12022_hwmon_read_temp(struct device *dev, long *mC)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	int temp, ret;
 	__le16 buf;

 	ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L, &buf, sizeof(buf));
 	if (ret)
 		return ret;
 	/*
 	 * Temperature is represented as a 10-bit number, unit half-Kelvins.
 	 */
 	temp = le16_to_cpu(buf);
 	temp *= 500;
 	temp -= 273000;

 	*mC = temp;

 	return 0;
 }

 static int isl12022_hwmon_read(struct device *dev,
 			       enum hwmon_sensor_types type,
 			       u32 attr, int channel, long *val)
 {
 	if (type == hwmon_temp && attr == hwmon_temp_input)
 		return isl12022_hwmon_read_temp(dev, val);

 	return -EOPNOTSUPP;
 }

 static const struct hwmon_channel_info * const isl12022_hwmon_info[] = {
 	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
 	NULL
 };

 static const struct hwmon_ops isl12022_hwmon_ops = {
 	.is_visible = isl12022_hwmon_is_visible,
 	.read = isl12022_hwmon_read,
 };

 static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
 	.ops = &isl12022_hwmon_ops,
 	.info = isl12022_hwmon_info,
 };

 static void isl12022_hwmon_register(struct device *dev)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	struct device *hwmon;
 	int ret;

 	if (!IS_REACHABLE(CONFIG_HWMON))
 		return;

 	ret = regmap_update_bits(regmap, ISL12022_REG_BETA,
 				 ISL12022_BETA_TSE, ISL12022_BETA_TSE);
 	if (ret) {
 		dev_warn(dev, "unable to enable temperature sensor\n");
 		return;
 	}

 	hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", regmap,
 						     &isl12022_hwmon_chip_info,
 						     NULL);
 	if (IS_ERR(hwmon))
 		dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
 }

 /*
  * In the routines that deal directly with the isl12022 hardware, we use
  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  */
 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	uint8_t buf[ISL12022_REG_INT + 1];
 	int ret;

 	ret = regmap_bulk_read(regmap, ISL12022_REG_SC, buf, sizeof(buf));
 	if (ret)
 		return ret;

 	dev_dbg(dev,
 		"raw data is sec=%02x, min=%02x, hr=%02x, mday=%02x, mon=%02x, year=%02x, wday=%02x, sr=%02x, int=%02x",
 		buf[ISL12022_REG_SC],
 		buf[ISL12022_REG_MN],
 		buf[ISL12022_REG_HR],
 		buf[ISL12022_REG_DT],
 		buf[ISL12022_REG_MO],
 		buf[ISL12022_REG_YR],
 		buf[ISL12022_REG_DW],
 		buf[ISL12022_REG_SR],
 		buf[ISL12022_REG_INT]);

 	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;

 	dev_dbg(dev, "%s: %ptR\n", __func__, tm);

 	return 0;
 }

 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	int ret;
 	uint8_t buf[ISL12022_REG_DW + 1];

 	dev_dbg(dev, "%s: %ptR\n", __func__, tm);

 	/* Ensure the write enable bit is set. */
 	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
 				 ISL12022_INT_WRTC, ISL12022_INT_WRTC);
 	if (ret)
 		return ret;

 	/* hours, minutes and seconds */
 	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;

 	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);

 	/* month, 1 - 12 */
 	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);

 	/* year and century */
 	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);

 	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;

 	return regmap_bulk_write(regmap, ISL12022_REG_SC, buf, sizeof(buf));
 }

 static int isl12022_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	u32 user, val;
 	int ret;

 	switch (cmd) {
 	case RTC_VL_READ:
 		ret = regmap_read(regmap, ISL12022_REG_SR, &val);
 		if (ret)
 			return ret;

 		user = 0;
 		if (val & ISL12022_SR_LBAT85)
 			user |= RTC_VL_BACKUP_LOW;

 		if (val & ISL12022_SR_LBAT75)
 			user |= RTC_VL_BACKUP_EMPTY;

 		return put_user(user, (u32 __user *)arg);

 	default:
 		return -ENOIOCTLCMD;
 	}
 }

 static const struct rtc_class_ops isl12022_rtc_ops = {
 	.ioctl		= isl12022_rtc_ioctl,
 	.read_time	= isl12022_rtc_read_time,
 	.set_time	= isl12022_rtc_set_time,
 };

 static const struct regmap_config regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.use_single_write = true,
 };

 static int isl12022_register_clock(struct device *dev)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	struct clk_hw *hw;
 	int ret;

 	if (!device_property_present(dev, "#clock-cells")) {
 		/*
 		 * Disabling the F_OUT pin reduces the power
 		 * consumption in battery mode by ~25%.
 		 */
 		regmap_update_bits(regmap, ISL12022_REG_INT, ISL12022_INT_FO_MASK,
 				   ISL12022_INT_FO_OFF);

 		return 0;
 	}

 	if (!IS_ENABLED(CONFIG_COMMON_CLK))
 		return 0;

 	/*
 	 * For now, only support a fixed clock of 32768Hz (the reset default).
 	 */
 	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
 				 ISL12022_INT_FO_MASK, ISL12022_INT_FO_32K);
 	if (ret)
 		return ret;

 	hw = devm_clk_hw_register_fixed_rate(dev, "isl12022", NULL, 0, 32768);
 	if (IS_ERR(hw))
 		return PTR_ERR(hw);

 	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
 }

 static const u32 trip_levels[2][7] = {
 	{ 2125000, 2295000, 2550000, 2805000, 3060000, 4250000, 4675000 },
 	{ 1875000, 2025000, 2250000, 2475000, 2700000, 3750000, 4125000 },
 };

 static void isl12022_set_trip_levels(struct device *dev)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	u32 levels[2] = {0, 0};
 	int ret, i, j, x[2];
 	u8 val, mask;

 	device_property_read_u32_array(dev, "isil,battery-trip-levels-microvolt",
 				       levels, 2);

 	for (i = 0; i < 2; i++) {
 		for (j = 0; j < ARRAY_SIZE(trip_levels[i]) - 1; j++) {
 			if (levels[i] <= trip_levels[i][j])
 				break;
 		}
 		x[i] = j;
 	}

 	val = FIELD_PREP(ISL12022_REG_VB85_MASK, x[0]) |
 		FIELD_PREP(ISL12022_REG_VB75_MASK, x[1]);
 	mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK;

 	ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
 	if (ret)
 		dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);

 	/*
 	 * Force a write of the TSE bit in the BETA register, in order
 	 * to trigger an update of the LBAT75 and LBAT85 bits in the
 	 * status register. In battery backup mode, those bits have
 	 * another meaning, so without this, they may contain stale
 	 * values for up to a minute after power-on.
 	 */
 	regmap_write_bits(regmap, ISL12022_REG_BETA,
 			  ISL12022_BETA_TSE, ISL12022_BETA_TSE);
 }

 static int isl12022_probe(struct i2c_client *client)
 {
 	struct rtc_device *rtc;
 	struct regmap *regmap;
 	int ret;

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

 	regmap = devm_regmap_init_i2c(client, &regmap_config);
 	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "regmap allocation failed\n");
 		return PTR_ERR(regmap);
 	}

 	dev_set_drvdata(&client->dev, regmap);

 	ret = isl12022_register_clock(&client->dev);
 	if (ret)
 		return ret;

 	isl12022_set_trip_levels(&client->dev);
 	isl12022_hwmon_register(&client->dev);

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

 	rtc->ops = &isl12022_rtc_ops;
 	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	rtc->range_max = RTC_TIMESTAMP_END_2099;

 	return devm_rtc_register_device(rtc);
 }

 static const struct of_device_id isl12022_dt_match[] = {
 	{ .compatible = "isl,isl12022" }, /* for backward compat., don't use */
 	{ .compatible = "isil,isl12022" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, isl12022_dt_match);

 static const struct i2c_device_id isl12022_id[] = {
 	{ "isl12022" },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, isl12022_id);

 static struct i2c_driver isl12022_driver = {
 	.driver		= {
 		.name	= "rtc-isl12022",
 		.of_match_table = isl12022_dt_match,
 	},
 	.probe		= isl12022_probe,
 	.id_table	= isl12022_id,
 };

 module_i2c_driver(isl12022_driver);

 MODULE_AUTHOR("roman.fietze@telemotive.de");
 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* An I2C driver for the Intersil ISL 12022
	*
	* Author: Roman Fietze <roman.fietze@telemotive.de>
	*
	* Based on the Philips PCF8563 RTC
	* by Alessandro Zummo <a.zummo@towertech.it>.
	*/

	#include <linux/bcd.h>
	#include <linux/bitfield.h>
	#include <linux/clk-provider.h>
	#include <linux/err.h>
	#include <linux/hwmon.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/regmap.h>
	#include <linux/rtc.h>
	#include <linux/slab.h>

	#include <asm/byteorder.h>

	/* ISL register offsets */
	#define ISL12022_REG_SC 0x00
	#define ISL12022_REG_MN 0x01
	#define ISL12022_REG_HR 0x02
	#define ISL12022_REG_DT 0x03
	#define ISL12022_REG_MO 0x04
	#define ISL12022_REG_YR 0x05
	#define ISL12022_REG_DW 0x06

	#define ISL12022_REG_SR 0x07
	#define ISL12022_REG_INT 0x08

	#define ISL12022_REG_PWR_VBAT 0x0a

	#define ISL12022_REG_BETA 0x0d
	#define ISL12022_REG_TEMP_L 0x28

	/* ISL register bits */
	#define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */

	#define ISL12022_SR_LBAT85 (1 << 2)
	#define ISL12022_SR_LBAT75 (1 << 1)

	#define ISL12022_INT_WRTC (1 << 6)
	#define ISL12022_INT_FO_MASK GENMASK(3, 0)
	#define ISL12022_INT_FO_OFF 0x0
	#define ISL12022_INT_FO_32K 0x1

	#define ISL12022_REG_VB85_MASK GENMASK(5, 3)
	#define ISL12022_REG_VB75_MASK GENMASK(2, 0)

	#define ISL12022_BETA_TSE (1 << 7)

	static umode_t isl12022_hwmon_is_visible(const void *data,
	enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	if (type == hwmon_temp && attr == hwmon_temp_input)
	return 0444;

	return 0;
	}

	/*
	* A user-initiated temperature conversion is not started by this function,
	* so the temperature is updated once every ~60 seconds.
	*/
	static int isl12022_hwmon_read_temp(struct device dev, long mC)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	int temp, ret;
	__le16 buf;

	ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L, &buf, sizeof(buf));
	if (ret)
	return ret;
	/*
	* Temperature is represented as a 10-bit number, unit half-Kelvins.
	*/
	temp = le16_to_cpu(buf);
	temp *= 500;
	temp -= 273000;

	*mC = temp;

	return 0;
	}

	static int isl12022_hwmon_read(struct device *dev,
	enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	if (type == hwmon_temp && attr == hwmon_temp_input)
	return isl12022_hwmon_read_temp(dev, val);

	return -EOPNOTSUPP;
	}

	static const struct hwmon_channel_info * const isl12022_hwmon_info[] = {
	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
	NULL
	};

	static const struct hwmon_ops isl12022_hwmon_ops = {
	.is_visible = isl12022_hwmon_is_visible,
	.read = isl12022_hwmon_read,
	};

	static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
	.ops = &isl12022_hwmon_ops,
	.info = isl12022_hwmon_info,
	};

	static void isl12022_hwmon_register(struct device *dev)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	struct device *hwmon;
	int ret;

	if (!IS_REACHABLE(CONFIG_HWMON))
	return;

	ret = regmap_update_bits(regmap, ISL12022_REG_BETA,
	ISL12022_BETA_TSE, ISL12022_BETA_TSE);
	if (ret) {
	dev_warn(dev, "unable to enable temperature sensor\n");
	return;
	}

	hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", regmap,
	&isl12022_hwmon_chip_info,
	NULL);
	if (IS_ERR(hwmon))
	dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
	}

	/*
	* In the routines that deal directly with the isl12022 hardware, we use
	* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
	*/
	static int isl12022_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	uint8_t buf[ISL12022_REG_INT + 1];
	int ret;

	ret = regmap_bulk_read(regmap, ISL12022_REG_SC, buf, sizeof(buf));
	if (ret)
	return ret;

	dev_dbg(dev,
	"raw data is sec=%02x, min=%02x, hr=%02x, mday=%02x, mon=%02x, year=%02x, wday=%02x, sr=%02x, int=%02x",
	buf[ISL12022_REG_SC],
	buf[ISL12022_REG_MN],
	buf[ISL12022_REG_HR],
	buf[ISL12022_REG_DT],
	buf[ISL12022_REG_MO],
	buf[ISL12022_REG_YR],
	buf[ISL12022_REG_DW],
	buf[ISL12022_REG_SR],
	buf[ISL12022_REG_INT]);

	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;

	dev_dbg(dev, "%s: %ptR\n", __func__, tm);

	return 0;
	}

	static int isl12022_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	int ret;
	uint8_t buf[ISL12022_REG_DW + 1];

	dev_dbg(dev, "%s: %ptR\n", __func__, tm);

	/* Ensure the write enable bit is set. */
	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
	ISL12022_INT_WRTC, ISL12022_INT_WRTC);
	if (ret)
	return ret;

	/* hours, minutes and seconds */
	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) \| ISL12022_HR_MIL;

	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);

	/* month, 1 - 12 */
	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);

	/* year and century */
	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);

	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;

	return regmap_bulk_write(regmap, ISL12022_REG_SC, buf, sizeof(buf));
	}

	static int isl12022_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	u32 user, val;
	int ret;

	switch (cmd) {
	case RTC_VL_READ:
	ret = regmap_read(regmap, ISL12022_REG_SR, &val);
	if (ret)
	return ret;

	user = 0;
	if (val & ISL12022_SR_LBAT85)
	user \|= RTC_VL_BACKUP_LOW;

	if (val & ISL12022_SR_LBAT75)
	user \|= RTC_VL_BACKUP_EMPTY;

	return put_user(user, (u32 __user *)arg);

	default:
	return -ENOIOCTLCMD;
	}
	}

	static const struct rtc_class_ops isl12022_rtc_ops = {
	.ioctl = isl12022_rtc_ioctl,
	.read_time = isl12022_rtc_read_time,
	.set_time = isl12022_rtc_set_time,
	};

	static const struct regmap_config regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.use_single_write = true,
	};

	static int isl12022_register_clock(struct device *dev)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	struct clk_hw *hw;
	int ret;

	if (!device_property_present(dev, "#clock-cells")) {
	/*
	* Disabling the F_OUT pin reduces the power
	* consumption in battery mode by ~25%.
	*/
	regmap_update_bits(regmap, ISL12022_REG_INT, ISL12022_INT_FO_MASK,
	ISL12022_INT_FO_OFF);

	return 0;
	}

	if (!IS_ENABLED(CONFIG_COMMON_CLK))
	return 0;

	/*
	* For now, only support a fixed clock of 32768Hz (the reset default).
	*/
	ret = regmap_update_bits(regmap, ISL12022_REG_INT,
	ISL12022_INT_FO_MASK, ISL12022_INT_FO_32K);
	if (ret)
	return ret;

	hw = devm_clk_hw_register_fixed_rate(dev, "isl12022", NULL, 0, 32768);
	if (IS_ERR(hw))
	return PTR_ERR(hw);

	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
	}

	static const u32 trip_levels[2][7] = {
	{ 2125000, 2295000, 2550000, 2805000, 3060000, 4250000, 4675000 },
	{ 1875000, 2025000, 2250000, 2475000, 2700000, 3750000, 4125000 },
	};

	static void isl12022_set_trip_levels(struct device *dev)
	{
	struct regmap *regmap = dev_get_drvdata(dev);
	u32 levels[2] = {0, 0};
	int ret, i, j, x[2];
	u8 val, mask;

	device_property_read_u32_array(dev, "isil,battery-trip-levels-microvolt",
	levels, 2);

	for (i = 0; i < 2; i++) {
	for (j = 0; j < ARRAY_SIZE(trip_levels[i]) - 1; j++) {
	if (levels[i] <= trip_levels[i][j])
	break;
	}
	x[i] = j;
	}

	val = FIELD_PREP(ISL12022_REG_VB85_MASK, x[0]) \|
	FIELD_PREP(ISL12022_REG_VB75_MASK, x[1]);
	mask = ISL12022_REG_VB85_MASK \| ISL12022_REG_VB75_MASK;

	ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
	if (ret)
	dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);

	/*
	* Force a write of the TSE bit in the BETA register, in order
	* to trigger an update of the LBAT75 and LBAT85 bits in the
	* status register. In battery backup mode, those bits have
	* another meaning, so without this, they may contain stale
	* values for up to a minute after power-on.
	*/
	regmap_write_bits(regmap, ISL12022_REG_BETA,
	ISL12022_BETA_TSE, ISL12022_BETA_TSE);
	}

	static int isl12022_probe(struct i2c_client *client)
	{
	struct rtc_device *rtc;
	struct regmap *regmap;
	int ret;

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

	regmap = devm_regmap_init_i2c(client, &regmap_config);
	if (IS_ERR(regmap)) {
	dev_err(&client->dev, "regmap allocation failed\n");
	return PTR_ERR(regmap);
	}

	dev_set_drvdata(&client->dev, regmap);

	ret = isl12022_register_clock(&client->dev);
	if (ret)
	return ret;

	isl12022_set_trip_levels(&client->dev);
	isl12022_hwmon_register(&client->dev);

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

	rtc->ops = &isl12022_rtc_ops;
	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
	rtc->range_max = RTC_TIMESTAMP_END_2099;

	return devm_rtc_register_device(rtc);
	}

	static const struct of_device_id isl12022_dt_match[] = {
	{ .compatible = "isl,isl12022" }, /* for backward compat., don't use */
	{ .compatible = "isil,isl12022" },
	{ },
	};
	MODULE_DEVICE_TABLE(of, isl12022_dt_match);

	static const struct i2c_device_id isl12022_id[] = {
	{ "isl12022" },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, isl12022_id);

	static struct i2c_driver isl12022_driver = {
	.driver = {
	.name = "rtc-isl12022",
	.of_match_table = isl12022_dt_match,
	},
	.probe = isl12022_probe,
	.id_table = isl12022_id,
	};

	module_i2c_driver(isl12022_driver);

	MODULE_AUTHOR("roman.fietze@telemotive.de");
	MODULE_DESCRIPTION("ISL 12022 RTC driver");
	MODULE_LICENSE("GPL");