linux/drivers/rtc/rtc-max31335.c

// SPDX-License-Identifier: GPL-2.0
/*
 * RTC driver for the MAX31335
 *
 * Copyright (C) 2023 Analog Devices
 *
 * Antoniu Miclaus <antoniu.miclaus@analog.com>
 *
 */

#include <asm-generic/unaligned.h>
#include <linux/bcd.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/util_macros.h>

/* MAX31335 Register Map */
#define MAX31335_STATUS1			0x00
#define MAX31335_INT_EN1			0x01
#define MAX31335_STATUS2			0x02
#define MAX31335_INT_EN2			0x03
#define MAX31335_RTC_RESET			0x04
#define MAX31335_RTC_CONFIG			0x05
#define MAX31335_RTC_CONFIG2			0x06
#define MAX31335_TIMESTAMP_CONFIG		0x07
#define MAX31335_TIMER_CONFIG			0x08
#define MAX31335_SECONDS_1_128			0x09
#define MAX31335_SECONDS			0x0A
#define MAX31335_MINUTES			0x0B
#define MAX31335_HOURS				0x0C
#define MAX31335_DAY				0x0D
#define MAX31335_DATE				0x0E
#define MAX31335_MONTH				0x0F
#define MAX31335_YEAR				0x0F
#define MAX31335_ALM1_SEC			0x11
#define MAX31335_ALM1_MIN			0x12
#define MAX31335_ALM1_HRS			0x13
#define MAX31335_ALM1_DAY_DATE			0x14
#define MAX31335_ALM1_MON			0x15
#define MAX31335_ALM1_YEAR			0x16
#define MAX31335_ALM2_MIN			0x17
#define MAX31335_ALM2_HRS			0x18
#define MAX31335_ALM2_DAY_DATE			0x19
#define MAX31335_TIMER_COUNT			0x1A
#define MAX31335_TIMER_INIT			0x1B
#define MAX31335_PWR_MGMT			0x1C
#define MAX31335_TRICKLE_REG			0x1D
#define MAX31335_AGING_OFFSET			0x1E
#define MAX31335_TS_CONFIG			0x30
#define MAX31335_TEMP_ALARM_HIGH_MSB		0x31
#define MAX31335_TEMP_ALARM_HIGH_LSB		0x32
#define MAX31335_TEMP_ALARM_LOW_MSB		0x33
#define MAX31335_TEMP_ALARM_LOW_LSB		0x34
#define MAX31335_TEMP_DATA_MSB			0x35
#define MAX31335_TEMP_DATA_LSB			0x36
#define MAX31335_TS0_SEC_1_128			0x40
#define MAX31335_TS0_SEC			0x41
#define MAX31335_TS0_MIN			0x42
#define MAX31335_TS0_HOUR			0x43
#define MAX31335_TS0_DATE			0x44
#define MAX31335_TS0_MONTH			0x45
#define MAX31335_TS0_YEAR			0x46
#define MAX31335_TS0_FLAGS			0x47
#define MAX31335_TS1_SEC_1_128			0x48
#define MAX31335_TS1_SEC			0x49
#define MAX31335_TS1_MIN			0x4A
#define MAX31335_TS1_HOUR			0x4B
#define MAX31335_TS1_DATE			0x4C
#define MAX31335_TS1_MONTH			0x4D
#define MAX31335_TS1_YEAR			0x4E
#define MAX31335_TS1_FLAGS			0x4F
#define MAX31335_TS2_SEC_1_128			0x50
#define MAX31335_TS2_SEC			0x51
#define MAX31335_TS2_MIN			0x52
#define MAX31335_TS2_HOUR			0x53
#define MAX31335_TS2_DATE			0x54
#define MAX31335_TS2_MONTH			0x55
#define MAX31335_TS2_YEAR			0x56
#define MAX31335_TS2_FLAGS			0x57
#define MAX31335_TS3_SEC_1_128			0x58
#define MAX31335_TS3_SEC			0x59
#define MAX31335_TS3_MIN			0x5A
#define MAX31335_TS3_HOUR			0x5B
#define MAX31335_TS3_DATE			0x5C
#define MAX31335_TS3_MONTH			0x5D
#define MAX31335_TS3_YEAR			0x5E
#define MAX31335_TS3_FLAGS			0x5F

/* MAX31335_STATUS1 Bit Definitions */
#define MAX31335_STATUS1_PSDECT			BIT(7)
#define MAX31335_STATUS1_OSF			BIT(6)
#define MAX31335_STATUS1_PFAIL			BIT(5)
#define MAX31335_STATUS1_VBATLOW		BIT(4)
#define MAX31335_STATUS1_DIF			BIT(3)
#define MAX31335_STATUS1_TIF			BIT(2)
#define MAX31335_STATUS1_A2F			BIT(1)
#define MAX31335_STATUS1_A1F			BIT(0)

/* MAX31335_INT_EN1 Bit Definitions */
#define MAX31335_INT_EN1_DOSF			BIT(6)
#define MAX31335_INT_EN1_PFAILE			BIT(5)
#define MAX31335_INT_EN1_VBATLOWE		BIT(4)
#define MAX31335_INT_EN1_DIE			BIT(3)
#define MAX31335_INT_EN1_TIE			BIT(2)
#define MAX31335_INT_EN1_A2IE			BIT(1)
#define MAX31335_INT_EN1_A1IE			BIT(0)

/* MAX31335_STATUS2 Bit Definitions */
#define MAX31335_STATUS2_TEMP_RDY		BIT(2)
#define MAX31335_STATUS2_OTF			BIT(1)
#define MAX31335_STATUS2_UTF			BIT(0)

/* MAX31335_INT_EN2 Bit Definitions */
#define MAX31335_INT_EN2_TEMP_RDY_EN		BIT(2)
#define MAX31335_INT_EN2_OTIE			BIT(1)
#define MAX31335_INT_EN2_UTIE			BIT(0)

/* MAX31335_RTC_RESET Bit Definitions */
#define MAX31335_RTC_RESET_SWRST		BIT(0)

/* MAX31335_RTC_CONFIG1 Bit Definitions */
#define MAX31335_RTC_CONFIG1_EN_IO		BIT(6)
#define MAX31335_RTC_CONFIG1_A1AC		GENMASK(5, 4)
#define MAX31335_RTC_CONFIG1_DIP		BIT(3)
#define MAX31335_RTC_CONFIG1_I2C_TIMEOUT	BIT(1)
#define MAX31335_RTC_CONFIG1_EN_OSC		BIT(0)

/* MAX31335_RTC_CONFIG2 Bit Definitions */
#define MAX31335_RTC_CONFIG2_ENCLKO		BIT(2)
#define MAX31335_RTC_CONFIG2_CLKO_HZ		GENMASK(1, 0)

/* MAX31335_TIMESTAMP_CONFIG Bit Definitions */
#define MAX31335_TIMESTAMP_CONFIG_TSVLOW	BIT(5)
#define MAX31335_TIMESTAMP_CONFIG_TSPWM		BIT(4)
#define MAX31335_TIMESTAMP_CONFIG_TSDIN		BIT(3)
#define MAX31335_TIMESTAMP_CONFIG_TSOW		BIT(2)
#define MAX31335_TIMESTAMP_CONFIG_TSR		BIT(1)
#define MAX31335_TIMESTAMP_CONFIG_TSE		BIT(0)

/* MAX31335_TIMER_CONFIG Bit Definitions */
#define MAX31335_TIMER_CONFIG_TE		BIT(4)
#define MAX31335_TIMER_CONFIG_TPAUSE		BIT(3)
#define MAX31335_TIMER_CONFIG_TRPT		BIT(2)
#define MAX31335_TIMER_CONFIG_TFS		GENMASK(1, 0)

/* MAX31335_HOURS Bit Definitions */
#define MAX31335_HOURS_F_24_12			BIT(6)
#define MAX31335_HOURS_HR_20_AM_PM		BIT(5)

/* MAX31335_MONTH Bit Definitions */
#define MAX31335_MONTH_CENTURY			BIT(7)

/* MAX31335_PWR_MGMT Bit Definitions */
#define MAX31335_PWR_MGMT_PFVT			BIT(0)

/* MAX31335_TRICKLE_REG Bit Definitions */
#define MAX31335_TRICKLE_REG_TRICKLE		GENMASK(3, 1)
#define MAX31335_TRICKLE_REG_EN_TRICKLE		BIT(0)

/* MAX31335_TS_CONFIG Bit Definitions */
#define MAX31335_TS_CONFIG_AUTO			BIT(4)
#define MAX31335_TS_CONFIG_CONVERT_T		BIT(3)
#define MAX31335_TS_CONFIG_TSINT		GENMASK(2, 0)

/* MAX31335_TS_FLAGS Bit Definitions */
#define MAX31335_TS_FLAGS_VLOWF			BIT(3)
#define MAX31335_TS_FLAGS_VBATF			BIT(2)
#define MAX31335_TS_FLAGS_VCCF			BIT(1)
#define MAX31335_TS_FLAGS_DINF			BIT(0)

/* MAX31335 Miscellaneous Definitions */
#define MAX31335_TRICKLE_SCHOTTKY_DIODE		1
#define MAX31335_TRICKLE_STANDARD_DIODE		4
#define MAX31335_RAM_SIZE			32
#define MAX31335_TIME_SIZE			0x07

#define clk_hw_to_max31335(_hw) container_of(_hw, struct max31335_data, clkout)

struct max31335_data {
	struct regmap *regmap;
	struct rtc_device *rtc;
	struct clk_hw clkout;
};

static const int max31335_clkout_freq[] = { 1, 64, 1024, 32768 };

static const u16 max31335_trickle_resistors[] = {3000, 6000, 11000};

static bool max31335_volatile_reg(struct device *dev, unsigned int reg)
{
	/* time keeping registers */
	if (reg >= MAX31335_SECONDS &&
	    reg < MAX31335_SECONDS + MAX31335_TIME_SIZE)
		return true;

	/* interrupt status register */
	if (reg == MAX31335_INT_EN1_A1IE)
		return true;

	/* temperature registers */
	if (reg == MAX31335_TEMP_DATA_MSB || reg == MAX31335_TEMP_DATA_LSB)
		return true;

	return false;
}

static const struct regmap_config regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = 0x5F,
	.volatile_reg = max31335_volatile_reg,
};

static int max31335_read_time(struct device *dev, struct rtc_time *tm)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	u8 date[7];
	int ret;

	ret = regmap_bulk_read(max31335->regmap, MAX31335_SECONDS, date,
			       sizeof(date));
	if (ret)
		return ret;

	tm->tm_sec  = bcd2bin(date[0] & 0x7f);
	tm->tm_min  = bcd2bin(date[1] & 0x7f);
	tm->tm_hour = bcd2bin(date[2] & 0x3f);
	tm->tm_wday = bcd2bin(date[3] & 0x7) - 1;
	tm->tm_mday = bcd2bin(date[4] & 0x3f);
	tm->tm_mon  = bcd2bin(date[5] & 0x1f) - 1;
	tm->tm_year = bcd2bin(date[6]) + 100;

	if (FIELD_GET(MAX31335_MONTH_CENTURY, date[5]))
		tm->tm_year += 100;

	return 0;
}

static int max31335_set_time(struct device *dev, struct rtc_time *tm)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	u8 date[7];

	date[0] = bin2bcd(tm->tm_sec);
	date[1] = bin2bcd(tm->tm_min);
	date[2] = bin2bcd(tm->tm_hour);
	date[3] = bin2bcd(tm->tm_wday + 1);
	date[4] = bin2bcd(tm->tm_mday);
	date[5] = bin2bcd(tm->tm_mon + 1);
	date[6] = bin2bcd(tm->tm_year % 100);

	if (tm->tm_year >= 200)
		date[5] |= FIELD_PREP(MAX31335_MONTH_CENTURY, 1);

	return regmap_bulk_write(max31335->regmap, MAX31335_SECONDS, date,
				 sizeof(date));
}

static int max31335_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	int ret, ctrl, status;
	struct rtc_time time;
	u8 regs[6];

	ret = regmap_bulk_read(max31335->regmap, MAX31335_ALM1_SEC, regs,
			       sizeof(regs));
	if (ret)
		return ret;

	alrm->time.tm_sec  = bcd2bin(regs[0] & 0x7f);
	alrm->time.tm_min  = bcd2bin(regs[1] & 0x7f);
	alrm->time.tm_hour = bcd2bin(regs[2] & 0x3f);
	alrm->time.tm_mday = bcd2bin(regs[3] & 0x3f);
	alrm->time.tm_mon  = bcd2bin(regs[4] & 0x1f) - 1;
	alrm->time.tm_year = bcd2bin(regs[5]) + 100;

	ret = max31335_read_time(dev, &time);
	if (ret)
		return ret;

	if (time.tm_year >= 200)
		alrm->time.tm_year += 100;

	ret = regmap_read(max31335->regmap, MAX31335_INT_EN1, &ctrl);
	if (ret)
		return ret;

	ret = regmap_read(max31335->regmap, MAX31335_STATUS1, &status);
	if (ret)
		return ret;

	alrm->enabled = FIELD_GET(MAX31335_INT_EN1_A1IE, ctrl);
	alrm->pending = FIELD_GET(MAX31335_STATUS1_A1F, status);

	return 0;
}

static int max31335_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	unsigned int reg;
	u8 regs[6];
	int ret;

	regs[0] = bin2bcd(alrm->time.tm_sec);
	regs[1] = bin2bcd(alrm->time.tm_min);
	regs[2] = bin2bcd(alrm->time.tm_hour);
	regs[3] = bin2bcd(alrm->time.tm_mday);
	regs[4] = bin2bcd(alrm->time.tm_mon + 1);
	regs[5] = bin2bcd(alrm->time.tm_year % 100);

	ret = regmap_bulk_write(max31335->regmap, MAX31335_ALM1_SEC,
				regs, sizeof(regs));
	if (ret)
		return ret;

	reg = FIELD_PREP(MAX31335_INT_EN1_A1IE, alrm->enabled);
	ret = regmap_update_bits(max31335->regmap, MAX31335_INT_EN1,
				 MAX31335_INT_EN1_A1IE, reg);
	if (ret)
		return ret;

	ret = regmap_update_bits(max31335->regmap, MAX31335_STATUS1,
				 MAX31335_STATUS1_A1F, 0);

	return 0;
}

static int max31335_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);

	return regmap_update_bits(max31335->regmap, MAX31335_INT_EN1,
				  MAX31335_INT_EN1_A1IE, enabled);
}

static irqreturn_t max31335_handle_irq(int irq, void *dev_id)
{
	struct max31335_data *max31335 = dev_id;
	bool status;
	int ret;

	ret = regmap_update_bits_check(max31335->regmap, MAX31335_STATUS1,
				       MAX31335_STATUS1_A1F, 0, &status);
	if (ret)
		return IRQ_HANDLED;

	if (status)
		rtc_update_irq(max31335->rtc, 1, RTC_AF | RTC_IRQF);

	return IRQ_HANDLED;
}

static const struct rtc_class_ops max31335_rtc_ops = {
	.read_time = max31335_read_time,
	.set_time = max31335_set_time,
	.read_alarm = max31335_read_alarm,
	.set_alarm = max31335_set_alarm,
	.alarm_irq_enable = max31335_alarm_irq_enable,
};

static int max31335_trickle_charger_setup(struct device *dev,
					  struct max31335_data *max31335)
{
	u32 ohms, chargeable;
	int i, trickle_cfg;
	const char *diode;

	if (device_property_read_u32(dev, "aux-voltage-chargeable",
				     &chargeable))
		return 0;

	if (device_property_read_u32(dev, "trickle-resistor-ohms", &ohms))
		return 0;

	if (device_property_read_string(dev, "adi,tc-diode", &diode))
		return 0;

	if (!strcmp(diode, "schottky"))
		trickle_cfg = MAX31335_TRICKLE_SCHOTTKY_DIODE;
	else if (!strcmp(diode, "standard+schottky"))
		trickle_cfg = MAX31335_TRICKLE_STANDARD_DIODE;
	else
		return dev_err_probe(dev, -EINVAL,
				     "Invalid tc-diode value: %s\n", diode);

	for (i = 0; i < ARRAY_SIZE(max31335_trickle_resistors); i++)
		if (ohms == max31335_trickle_resistors[i])
			break;

	if (i >= ARRAY_SIZE(max31335_trickle_resistors))
		return 0;

	i = i + trickle_cfg;

	return regmap_write(max31335->regmap, MAX31335_TRICKLE_REG,
			    FIELD_PREP(MAX31335_TRICKLE_REG_TRICKLE, i) |
			    FIELD_PREP(MAX31335_TRICKLE_REG_EN_TRICKLE,
				       chargeable));
}

static unsigned long max31335_clkout_recalc_rate(struct clk_hw *hw,
						 unsigned long parent_rate)
{
	struct max31335_data *max31335 = clk_hw_to_max31335(hw);
	unsigned int freq_mask;
	unsigned int reg;
	int ret;

	ret = regmap_read(max31335->regmap, MAX31335_RTC_CONFIG2, &reg);
	if (ret)
		return 0;

	freq_mask = __roundup_pow_of_two(ARRAY_SIZE(max31335_clkout_freq)) - 1;

	return max31335_clkout_freq[reg & freq_mask];
}

static long max31335_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
				       unsigned long *prate)
{
	int index;

	index = find_closest(rate, max31335_clkout_freq,
			     ARRAY_SIZE(max31335_clkout_freq));

	return max31335_clkout_freq[index];
}

static int max31335_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
				    unsigned long parent_rate)
{
	struct max31335_data *max31335 = clk_hw_to_max31335(hw);
	unsigned int freq_mask;
	int index;

	index = find_closest(rate, max31335_clkout_freq,
			     ARRAY_SIZE(max31335_clkout_freq));
	freq_mask = __roundup_pow_of_two(ARRAY_SIZE(max31335_clkout_freq)) - 1;

	return regmap_update_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
				  freq_mask, index);
}

static int max31335_clkout_enable(struct clk_hw *hw)
{
	struct max31335_data *max31335 = clk_hw_to_max31335(hw);

	return regmap_set_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
			       MAX31335_RTC_CONFIG2_ENCLKO);
}

static void max31335_clkout_disable(struct clk_hw *hw)
{
	struct max31335_data *max31335 = clk_hw_to_max31335(hw);

	regmap_clear_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
			  MAX31335_RTC_CONFIG2_ENCLKO);
}

static int max31335_clkout_is_enabled(struct clk_hw *hw)
{
	struct max31335_data *max31335 = clk_hw_to_max31335(hw);
	unsigned int reg;
	int ret;

	ret = regmap_read(max31335->regmap, MAX31335_RTC_CONFIG2, &reg);
	if (ret)
		return ret;

	return !!(reg & MAX31335_RTC_CONFIG2_ENCLKO);
}

static const struct clk_ops max31335_clkout_ops = {
	.recalc_rate = max31335_clkout_recalc_rate,
	.round_rate = max31335_clkout_round_rate,
	.set_rate = max31335_clkout_set_rate,
	.enable = max31335_clkout_enable,
	.disable = max31335_clkout_disable,
	.is_enabled = max31335_clkout_is_enabled,
};

static struct clk_init_data max31335_clk_init = {
	.name = "max31335-clkout",
	.ops = &max31335_clkout_ops,
};

static int max31335_nvmem_reg_read(void *priv, unsigned int offset,
				   void *val, size_t bytes)
{
	struct max31335_data *max31335 = priv;
	unsigned int reg = MAX31335_TS0_SEC_1_128 + offset;

	return regmap_bulk_read(max31335->regmap, reg, val, bytes);
}

static int max31335_nvmem_reg_write(void *priv, unsigned int offset,
				    void *val, size_t bytes)
{
	struct max31335_data *max31335 = priv;
	unsigned int reg = MAX31335_TS0_SEC_1_128 + offset;

	return regmap_bulk_write(max31335->regmap, reg, val, bytes);
}

static struct nvmem_config max31335_nvmem_cfg = {
	.reg_read = max31335_nvmem_reg_read,
	.reg_write = max31335_nvmem_reg_write,
	.word_size = 8,
	.size = MAX31335_RAM_SIZE,
};

#if IS_REACHABLE(HWMON)
static int max31335_read_temp(struct device *dev, enum hwmon_sensor_types type,
			      u32 attr, int channel, long *val)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	u8 reg[2];
	s16 temp;
	int ret;

	if (type != hwmon_temp || attr != hwmon_temp_input)
		return -EOPNOTSUPP;

	ret = regmap_bulk_read(max31335->regmap, MAX31335_TEMP_DATA_MSB,
			       reg, 2);
	if (ret)
		return ret;

	temp = get_unaligned_be16(reg);

	*val = (temp / 64) * 250;

	return 0;
}

static umode_t max31335_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;
}

static const struct hwmon_channel_info *max31335_info[] = {
	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
	NULL
};

static const struct hwmon_ops max31335_hwmon_ops = {
	.is_visible = max31335_is_visible,
	.read = max31335_read_temp,
};

static const struct hwmon_chip_info max31335_chip_info = {
	.ops = &max31335_hwmon_ops,
	.info = max31335_info,
};
#endif

static int max31335_clkout_register(struct device *dev)
{
	struct max31335_data *max31335 = dev_get_drvdata(dev);
	int ret;

	if (!device_property_present(dev, "#clock-cells"))
		return regmap_clear_bits(max31335->regmap, MAX31335_RTC_CONFIG2,
					 MAX31335_RTC_CONFIG2_ENCLKO);

	max31335->clkout.init = &max31335_clk_init;

	ret = devm_clk_hw_register(dev, &max31335->clkout);
	if (ret)
		return dev_err_probe(dev, ret, "cannot register clock\n");

	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
					  &max31335->clkout);
	if (ret)
		return dev_err_probe(dev, ret, "cannot add hw provider\n");

	max31335->clkout.clk = devm_clk_get_enabled(dev, NULL);
	if (IS_ERR(max31335->clkout.clk))
		return dev_err_probe(dev, PTR_ERR(max31335->clkout.clk),
				     "cannot enable clkout\n");

	return 0;
}

static int max31335_probe(struct i2c_client *client)
{
	struct max31335_data *max31335;
#if IS_REACHABLE(HWMON)
	struct device *hwmon;
#endif
	int ret;

	max31335 = devm_kzalloc(&client->dev, sizeof(*max31335), GFP_KERNEL);
	if (!max31335)
		return -ENOMEM;

	max31335->regmap = devm_regmap_init_i2c(client, &regmap_config);
	if (IS_ERR(max31335->regmap))
		return PTR_ERR(max31335->regmap);

	i2c_set_clientdata(client, max31335);

	max31335->rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(max31335->rtc))
		return PTR_ERR(max31335->rtc);

	max31335->rtc->ops = &max31335_rtc_ops;
	max31335->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
	max31335->rtc->range_max = RTC_TIMESTAMP_END_2199;
	max31335->rtc->alarm_offset_max = 24 * 60 * 60;

	ret = max31335_clkout_register(&client->dev);
	if (ret)
		return ret;

	if (client->irq > 0) {
		ret = devm_request_threaded_irq(&client->dev, client->irq,
						NULL, max31335_handle_irq,
						IRQF_ONESHOT,
						"max31335", max31335);
		if (ret) {
			dev_warn(&client->dev,
				 "unable to request IRQ, alarm max31335 disabled\n");
			client->irq = 0;
		}
	}

	if (!client->irq)
		clear_bit(RTC_FEATURE_ALARM, max31335->rtc->features);

	max31335_nvmem_cfg.priv = max31335;
	ret = devm_rtc_nvmem_register(max31335->rtc, &max31335_nvmem_cfg);
	if (ret)
		return dev_err_probe(&client->dev, ret,
				     "cannot register rtc nvmem\n");

#if IS_REACHABLE(HWMON)
	hwmon = devm_hwmon_device_register_with_info(&client->dev, client->name,
						     max31335,
						     &max31335_chip_info,
						     NULL);
	if (IS_ERR(hwmon))
		return dev_err_probe(&client->dev, PTR_ERR(hwmon),
				     "cannot register hwmon device\n");
#endif

	ret = max31335_trickle_charger_setup(&client->dev, max31335);
	if (ret)
		return ret;

	return devm_rtc_register_device(max31335->rtc);
}

static const struct i2c_device_id max31335_id[] = {
	{ "max31335", 0 },
	{ }
};

MODULE_DEVICE_TABLE(i2c, max31335_id);

static const struct of_device_id max31335_of_match[] = {
	{ .compatible = "adi,max31335" },
	{ }
};

MODULE_DEVICE_TABLE(of, max31335_of_match);

static struct i2c_driver max31335_driver = {
	.driver = {
		.name = "rtc-max31335",
		.of_match_table = max31335_of_match,
	},
	.probe = max31335_probe,
	.id_table = max31335_id,
};
module_i2c_driver(max31335_driver);

MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com>");
MODULE_DESCRIPTION("MAX31335 RTC driver");
MODULE_LICENSE("GPL");