root/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 <linux/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

/* MAX31331 Register Map */
#define MAX31331_RTC_CONFIG2                    0x04

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

/* Supported Maxim RTC */
enum max_rtc_ids {
        ID_MAX31331,
        ID_MAX31335,
        MAX_RTC_ID_NR
};

struct chip_desc {
        u8 sec_reg;
        u8 alarm1_sec_reg;

        u8 int_en_reg;
        u8 int_status_reg;

        u8 ram_reg;
        u8 ram_size;

        u8 temp_reg;

        u8 trickle_reg;

        u8 clkout_reg;

        enum max_rtc_ids id;
};

struct max31335_data {
        struct regmap *regmap;
        struct rtc_device *rtc;
        struct clk_hw clkout;
        struct clk *clkin;
        const struct chip_desc *chip;
        int irq;
};

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

static const struct chip_desc chip[MAX_RTC_ID_NR] = {
        [ID_MAX31331] = {
                .id = ID_MAX31331,
                .int_en_reg = 0x01,
                .int_status_reg = 0x00,
                .sec_reg = 0x08,
                .alarm1_sec_reg = 0x0F,
                .ram_reg = 0x20,
                .ram_size = 32,
                .trickle_reg = 0x1B,
                .clkout_reg = 0x04,
        },
        [ID_MAX31335] = {
                .id = ID_MAX31335,
                .int_en_reg = 0x01,
                .int_status_reg = 0x00,
                .sec_reg = 0x0A,
                .alarm1_sec_reg = 0x11,
                .ram_reg = 0x40,
                .ram_size = 32,
                .temp_reg = 0x35,
                .trickle_reg = 0x1D,
                .clkout_reg = 0x06,
        },
};

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

static bool max31335_volatile_reg(struct device *dev, unsigned int reg)
{
        struct max31335_data *max31335 = dev_get_drvdata(dev);
        const struct chip_desc *chip = max31335->chip;

        /* time keeping registers */
        if (reg >= chip->sec_reg && reg < chip->sec_reg + MAX31335_TIME_SIZE)
                return true;

        /* interrupt status register */
        if (reg == chip->int_status_reg)
                return true;

        /* temperature registers if valid */
        if (chip->temp_reg && (reg == chip->temp_reg || reg == chip->temp_reg + 1))
                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->chip->sec_reg, 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->chip->sec_reg, 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->chip->alarm1_sec_reg, 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->chip->int_en_reg, &ctrl);
        if (ret)
                return ret;

        ret = regmap_read(max31335->regmap, max31335->chip->int_status_reg, &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->chip->alarm1_sec_reg,
                                regs, sizeof(regs));
        if (ret)
                return ret;

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

        return regmap_update_bits(max31335->regmap, max31335->chip->int_status_reg,
                                  MAX31335_STATUS1_A1F, 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->chip->int_en_reg,
                                  MAX31335_INT_EN1_A1IE, enabled);
}

static irqreturn_t max31335_handle_irq(int irq, void *dev_id)
{
        struct max31335_data *max31335 = dev_id;
        struct mutex *lock = &max31335->rtc->ops_lock;
        int ret, status;

        mutex_lock(lock);

        ret = regmap_read(max31335->regmap, max31335->chip->int_status_reg, &status);
        if (ret)
                goto exit;

        if (FIELD_GET(MAX31335_STATUS1_A1F, status)) {
                ret = regmap_update_bits(max31335->regmap, max31335->chip->int_status_reg,
                                         MAX31335_STATUS1_A1F, 0);
                if (ret)
                        goto exit;

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

exit:
        mutex_unlock(lock);

        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->chip->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->chip->clkout_reg, &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 int max31335_clkout_determine_rate(struct clk_hw *hw,
                                          struct clk_rate_request *req)
{
        int index;

        index = find_closest(req->rate, max31335_clkout_freq,
                             ARRAY_SIZE(max31335_clkout_freq));

        req->rate = max31335_clkout_freq[index];

        return 0;
}

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->chip->clkout_reg,
                                 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->chip->clkout_reg,
                              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->chip->clkout_reg,
                          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->chip->clkout_reg, &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,
        .determine_rate = max31335_clkout_determine_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->chip->ram_reg + 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->chip->ram_reg + 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(CONFIG_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->chip->temp_reg,
                               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->chip->clkout_reg,
                                  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(CONFIG_HWMON)
        struct device *hwmon;
#endif
        const struct chip_desc *match;
        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);
        match = i2c_get_match_data(client);
        if (!match)
                return -ENODEV;
        max31335->chip = match;
        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;
                } else {
                        max31335->irq = client->irq;
                }
        }

        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(CONFIG_HWMON)
        if (max31335->chip->temp_reg) {
                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[] = {
        { "max31331", (kernel_ulong_t)&chip[ID_MAX31331] },
        { "max31335", (kernel_ulong_t)&chip[ID_MAX31335] },
        { }
};

MODULE_DEVICE_TABLE(i2c, max31335_id);

static const struct of_device_id max31335_of_match[] = {
        { .compatible = "adi,max31331", .data = &chip[ID_MAX31331] },
        { .compatible = "adi,max31335", .data = &chip[ID_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_AUTHOR("Saket Kumar Purwar <Saket.Kumarpurwar@analog.com>");
MODULE_DESCRIPTION("MAX31335 RTC driver");
MODULE_LICENSE("GPL");