root/drivers/rtc/rtc-ab-eoz9.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Real Time Clock driver for AB-RTCMC-32.768kHz-EOZ9 chip.
 * Copyright (C) 2019 Orolia
 *
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/bitfield.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>

#define ABEOZ9_REG_CTRL1                0x00
#define ABEOZ9_REG_CTRL1_MASK           GENMASK(7, 0)
#define ABEOZ9_REG_CTRL1_WE             BIT(0)
#define ABEOZ9_REG_CTRL1_TE             BIT(1)
#define ABEOZ9_REG_CTRL1_TAR            BIT(2)
#define ABEOZ9_REG_CTRL1_EERE           BIT(3)
#define ABEOZ9_REG_CTRL1_SRON           BIT(4)
#define ABEOZ9_REG_CTRL1_TD0            BIT(5)
#define ABEOZ9_REG_CTRL1_TD1            BIT(6)
#define ABEOZ9_REG_CTRL1_CLKINT         BIT(7)

#define ABEOZ9_REG_CTRL_INT             0x01
#define ABEOZ9_REG_CTRL_INT_AIE         BIT(0)
#define ABEOZ9_REG_CTRL_INT_TIE         BIT(1)
#define ABEOZ9_REG_CTRL_INT_V1IE        BIT(2)
#define ABEOZ9_REG_CTRL_INT_V2IE        BIT(3)
#define ABEOZ9_REG_CTRL_INT_SRIE        BIT(4)

#define ABEOZ9_REG_CTRL_INT_FLAG        0x02
#define ABEOZ9_REG_CTRL_INT_FLAG_AF     BIT(0)
#define ABEOZ9_REG_CTRL_INT_FLAG_TF     BIT(1)
#define ABEOZ9_REG_CTRL_INT_FLAG_V1IF   BIT(2)
#define ABEOZ9_REG_CTRL_INT_FLAG_V2IF   BIT(3)
#define ABEOZ9_REG_CTRL_INT_FLAG_SRF    BIT(4)

#define ABEOZ9_REG_CTRL_STATUS          0x03
#define ABEOZ9_REG_CTRL_STATUS_V1F      BIT(2)
#define ABEOZ9_REG_CTRL_STATUS_V2F      BIT(3)
#define ABEOZ9_REG_CTRL_STATUS_SR       BIT(4)
#define ABEOZ9_REG_CTRL_STATUS_PON      BIT(5)
#define ABEOZ9_REG_CTRL_STATUS_EEBUSY   BIT(7)

#define ABEOZ9_REG_SEC                  0x08
#define ABEOZ9_REG_MIN                  0x09
#define ABEOZ9_REG_HOURS                0x0A
#define ABEOZ9_HOURS_PM                 BIT(6)
#define ABEOZ9_REG_DAYS                 0x0B
#define ABEOZ9_REG_WEEKDAYS             0x0C
#define ABEOZ9_REG_MONTHS               0x0D
#define ABEOZ9_REG_YEARS                0x0E

#define ABEOZ9_SEC_LEN                  7

#define ABEOZ9_REG_ALARM_SEC            0x10
#define ABEOZ9_BIT_ALARM_SEC            GENMASK(6, 0)
#define ABEOZ9_REG_ALARM_MIN            0x11
#define ABEOZ9_BIT_ALARM_MIN            GENMASK(6, 0)
#define ABEOZ9_REG_ALARM_HOURS          0x12
#define ABEOZ9_BIT_ALARM_HOURS_PM       BIT(5)
#define ABEOZ9_BIT_ALARM_HOURS          GENMASK(5, 0)
#define ABEOZ9_REG_ALARM_DAYS           0x13
#define ABEOZ9_BIT_ALARM_DAYS           GENMASK(5, 0)
#define ABEOZ9_REG_ALARM_WEEKDAYS       0x14
#define ABEOZ9_BIT_ALARM_WEEKDAYS       GENMASK(2, 0)
#define ABEOZ9_REG_ALARM_MONTHS         0x15
#define ABEOZ9_BIT_ALARM_MONTHS         GENMASK(4, 0)
#define ABEOZ9_REG_ALARM_YEARS          0x16

#define ABEOZ9_ALARM_LEN                7
#define ABEOZ9_BIT_ALARM_AE             BIT(7)

#define ABEOZ9_REG_REG_TEMP             0x20
#define ABEOZ953_TEMP_MAX               120
#define ABEOZ953_TEMP_MIN               -60

#define ABEOZ9_REG_EEPROM               0x30
#define ABEOZ9_REG_EEPROM_MASK          GENMASK(8, 0)
#define ABEOZ9_REG_EEPROM_THP           BIT(0)
#define ABEOZ9_REG_EEPROM_THE           BIT(1)
#define ABEOZ9_REG_EEPROM_FD0           BIT(2)
#define ABEOZ9_REG_EEPROM_FD1           BIT(3)
#define ABEOZ9_REG_EEPROM_R1K           BIT(4)
#define ABEOZ9_REG_EEPROM_R5K           BIT(5)
#define ABEOZ9_REG_EEPROM_R20K          BIT(6)
#define ABEOZ9_REG_EEPROM_R80K          BIT(7)

struct abeoz9_rtc_data {
        struct rtc_device *rtc;
        struct regmap *regmap;
        struct device *hwmon_dev;
};

static int abeoz9_check_validity(struct device *dev)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        int ret;
        int val;

        ret = regmap_read(regmap, ABEOZ9_REG_CTRL_STATUS, &val);
        if (ret < 0) {
                dev_err(dev,
                        "unable to get CTRL_STATUS register (%d)\n", ret);
                return ret;
        }

        if (val & ABEOZ9_REG_CTRL_STATUS_PON) {
                dev_warn(dev, "power-on reset detected, date is invalid\n");
                return -EINVAL;
        }

        if (val & ABEOZ9_REG_CTRL_STATUS_V1F) {
                dev_warn(dev,
                         "voltage drops below VLOW1 threshold, date is invalid\n");
                return -EINVAL;
        }

        if ((val & ABEOZ9_REG_CTRL_STATUS_V2F)) {
                dev_warn(dev,
                         "voltage drops below VLOW2 threshold, date is invalid\n");
                return -EINVAL;
        }

        return 0;
}

static int abeoz9_reset_validity(struct regmap *regmap)
{
        return regmap_update_bits(regmap, ABEOZ9_REG_CTRL_STATUS,
                                  ABEOZ9_REG_CTRL_STATUS_V1F |
                                  ABEOZ9_REG_CTRL_STATUS_V2F |
                                  ABEOZ9_REG_CTRL_STATUS_PON,
                                  0);
}

static int abeoz9_rtc_get_time(struct device *dev, struct rtc_time *tm)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        u8 regs[ABEOZ9_SEC_LEN];
        int ret;

        ret = abeoz9_check_validity(dev);
        if (ret)
                return ret;

        ret = regmap_bulk_read(data->regmap, ABEOZ9_REG_SEC,
                               regs,
                               sizeof(regs));
        if (ret) {
                dev_err(dev, "reading RTC time failed (%d)\n", ret);
                return ret;
        }

        tm->tm_sec = bcd2bin(regs[ABEOZ9_REG_SEC - ABEOZ9_REG_SEC] & 0x7F);
        tm->tm_min = bcd2bin(regs[ABEOZ9_REG_MIN - ABEOZ9_REG_SEC] & 0x7F);

        if (regs[ABEOZ9_REG_HOURS - ABEOZ9_REG_SEC] & ABEOZ9_HOURS_PM) {
                tm->tm_hour =
                        bcd2bin(regs[ABEOZ9_REG_HOURS - ABEOZ9_REG_SEC] & 0x1f);
                if (regs[ABEOZ9_REG_HOURS - ABEOZ9_REG_SEC] & ABEOZ9_HOURS_PM)
                        tm->tm_hour += 12;
        } else {
                tm->tm_hour = bcd2bin(regs[ABEOZ9_REG_HOURS - ABEOZ9_REG_SEC]);
        }

        tm->tm_mday = bcd2bin(regs[ABEOZ9_REG_DAYS - ABEOZ9_REG_SEC]);
        tm->tm_wday = bcd2bin(regs[ABEOZ9_REG_WEEKDAYS - ABEOZ9_REG_SEC]);
        tm->tm_mon  = bcd2bin(regs[ABEOZ9_REG_MONTHS - ABEOZ9_REG_SEC]) - 1;
        tm->tm_year = bcd2bin(regs[ABEOZ9_REG_YEARS - ABEOZ9_REG_SEC]) + 100;

        return ret;
}

static int abeoz9_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u8 regs[ABEOZ9_SEC_LEN];
        int ret;

        regs[ABEOZ9_REG_SEC - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_sec);
        regs[ABEOZ9_REG_MIN - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_min);
        regs[ABEOZ9_REG_HOURS - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_hour);
        regs[ABEOZ9_REG_DAYS - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_mday);
        regs[ABEOZ9_REG_WEEKDAYS - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_wday);
        regs[ABEOZ9_REG_MONTHS - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_mon + 1);
        regs[ABEOZ9_REG_YEARS - ABEOZ9_REG_SEC] = bin2bcd(tm->tm_year - 100);

        ret = regmap_bulk_write(data->regmap, ABEOZ9_REG_SEC,
                                regs,
                                sizeof(regs));

        if (ret) {
                dev_err(dev, "set RTC time failed (%d)\n", ret);
                return ret;
        }

        return abeoz9_reset_validity(regmap);
}

static int abeoz9_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u8 regs[ABEOZ9_ALARM_LEN];
        u8 val[2];
        int ret;

        ret = abeoz9_check_validity(dev);
        if (ret)
                return ret;

        ret = regmap_bulk_read(regmap, ABEOZ9_REG_CTRL_INT, val, sizeof(val));
        if (ret)
                return ret;

        alarm->enabled = val[0] & ABEOZ9_REG_CTRL_INT_AIE;
        alarm->pending = val[1] & ABEOZ9_REG_CTRL_INT_FLAG_AF;

        ret = regmap_bulk_read(regmap, ABEOZ9_REG_ALARM_SEC, regs, sizeof(regs));
        if (ret)
                return ret;

        alarm->time.tm_sec = bcd2bin(FIELD_GET(ABEOZ9_BIT_ALARM_SEC, regs[0]));
        alarm->time.tm_min = bcd2bin(FIELD_GET(ABEOZ9_BIT_ALARM_MIN, regs[1]));
        alarm->time.tm_hour = bcd2bin(FIELD_GET(ABEOZ9_BIT_ALARM_HOURS, regs[2]));

        alarm->time.tm_mday = bcd2bin(FIELD_GET(ABEOZ9_BIT_ALARM_DAYS, regs[3]));

        return 0;
}

static int abeoz9_rtc_alarm_irq_enable(struct device *dev, u32 enable)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);

        return regmap_update_bits(data->regmap, ABEOZ9_REG_CTRL_INT,
                                  ABEOZ9_REG_CTRL_INT_AIE,
                                  FIELD_PREP(ABEOZ9_REG_CTRL_INT_AIE, enable));
}

static int abeoz9_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        u8 regs[ABEOZ9_ALARM_LEN] = {0};
        int ret;

        ret = regmap_update_bits(data->regmap, ABEOZ9_REG_CTRL_INT_FLAG,
                                 ABEOZ9_REG_CTRL_INT_FLAG_AF, 0);
        if (ret)
                return ret;

        regs[0] = ABEOZ9_BIT_ALARM_AE | FIELD_PREP(ABEOZ9_BIT_ALARM_SEC,
                                                   bin2bcd(alarm->time.tm_sec));
        regs[1] = ABEOZ9_BIT_ALARM_AE | FIELD_PREP(ABEOZ9_BIT_ALARM_MIN,
                                                   bin2bcd(alarm->time.tm_min));
        regs[2] = ABEOZ9_BIT_ALARM_AE | FIELD_PREP(ABEOZ9_BIT_ALARM_HOURS,
                                                   bin2bcd(alarm->time.tm_hour));
        regs[3] = ABEOZ9_BIT_ALARM_AE | FIELD_PREP(ABEOZ9_BIT_ALARM_DAYS,
                                                   bin2bcd(alarm->time.tm_mday));

        ret = regmap_bulk_write(data->regmap, ABEOZ9_REG_ALARM_SEC, regs,
                                sizeof(regs));
        if (ret)
                return ret;

        return abeoz9_rtc_alarm_irq_enable(dev, alarm->enabled);
}

static irqreturn_t abeoz9_rtc_irq(int irq, void *dev)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        unsigned int val;
        int ret;

        ret = regmap_read(data->regmap, ABEOZ9_REG_CTRL_INT_FLAG, &val);
        if (ret)
                return IRQ_NONE;

        if (!FIELD_GET(ABEOZ9_REG_CTRL_INT_FLAG_AF, val))
                return IRQ_NONE;

        regmap_update_bits(data->regmap, ABEOZ9_REG_CTRL_INT_FLAG,
                           ABEOZ9_REG_CTRL_INT_FLAG_AF, 0);

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

        return IRQ_HANDLED;
}

static int abeoz9_trickle_parse_dt(struct device_node *node)
{
        u32 ohms = 0;

        if (of_property_read_u32(node, "trickle-resistor-ohms", &ohms))
                return 0;

        switch (ohms) {
        case 1000:
                return ABEOZ9_REG_EEPROM_R1K;
        case 5000:
                return ABEOZ9_REG_EEPROM_R5K;
        case 20000:
                return ABEOZ9_REG_EEPROM_R20K;
        case 80000:
                return ABEOZ9_REG_EEPROM_R80K;
        default:
                return 0;
        }
}

static int abeoz9_rtc_setup(struct device *dev, struct device_node *node)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        int ret;

        /* Enable Self Recovery, Clock for Watch and EEPROM refresh functions */
        ret = regmap_update_bits(regmap, ABEOZ9_REG_CTRL1,
                                 ABEOZ9_REG_CTRL1_MASK,
                                 ABEOZ9_REG_CTRL1_WE |
                                 ABEOZ9_REG_CTRL1_EERE |
                                 ABEOZ9_REG_CTRL1_SRON);
        if (ret < 0) {
                dev_err(dev, "unable to set CTRL_1 register (%d)\n", ret);
                return ret;
        }

        ret = regmap_write(regmap, ABEOZ9_REG_CTRL_INT, 0);
        if (ret < 0) {
                dev_err(dev,
                        "unable to set control CTRL_INT register (%d)\n",
                        ret);
                return ret;
        }

        ret = regmap_write(regmap, ABEOZ9_REG_CTRL_INT_FLAG, 0);
        if (ret < 0) {
                dev_err(dev,
                        "unable to set control CTRL_INT_FLAG register (%d)\n",
                        ret);
                return ret;
        }

        ret = abeoz9_trickle_parse_dt(node);

        /* Enable built-in termometer */
        ret |= ABEOZ9_REG_EEPROM_THE;

        ret = regmap_update_bits(regmap, ABEOZ9_REG_EEPROM,
                                 ABEOZ9_REG_EEPROM_MASK,
                                 ret);
        if (ret < 0) {
                dev_err(dev, "unable to set EEPROM register (%d)\n", ret);
                return ret;
        }

        return ret;
}

static const struct rtc_class_ops rtc_ops = {
        .read_time = abeoz9_rtc_get_time,
        .set_time = abeoz9_rtc_set_time,
        .read_alarm = abeoz9_rtc_read_alarm,
        .set_alarm = abeoz9_rtc_set_alarm,
        .alarm_irq_enable = abeoz9_rtc_alarm_irq_enable,
};

static const struct regmap_config abeoz9_rtc_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = 0x3f,
};

#if IS_REACHABLE(CONFIG_HWMON)

static int abeoz9z3_temp_read(struct device *dev,
                              enum hwmon_sensor_types type,
                              u32 attr, int channel, long *temp)
{
        struct abeoz9_rtc_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        int ret;
        unsigned int val;

        ret = regmap_read(regmap, ABEOZ9_REG_CTRL_STATUS, &val);
        if (ret < 0)
                return ret;

        switch (attr) {
        case hwmon_temp_input:
                ret = regmap_read(regmap, ABEOZ9_REG_REG_TEMP, &val);
                if (ret < 0)
                        return ret;
                *temp = 1000 * (val + ABEOZ953_TEMP_MIN);
                return 0;
        case hwmon_temp_max:
                *temp = 1000 * ABEOZ953_TEMP_MAX;
                return 0;
        case hwmon_temp_min:
                *temp = 1000 * ABEOZ953_TEMP_MIN;
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t abeoz9_is_visible(const void *data,
                                 enum hwmon_sensor_types type,
                                 u32 attr, int channel)
{
        switch (attr) {
        case hwmon_temp_input:
        case hwmon_temp_max:
        case hwmon_temp_min:
                return 0444;
        default:
                return 0;
        }
}

static const struct hwmon_channel_info * const abeoz9_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN),
        NULL
};

static const struct hwmon_ops abeoz9_hwmon_ops = {
        .is_visible = abeoz9_is_visible,
        .read = abeoz9z3_temp_read,
};

static const struct hwmon_chip_info abeoz9_chip_info = {
        .ops = &abeoz9_hwmon_ops,
        .info = abeoz9_info,
};

static void abeoz9_hwmon_register(struct device *dev,
                                  struct abeoz9_rtc_data *data)
{
        data->hwmon_dev =
                devm_hwmon_device_register_with_info(dev,
                                                     "abeoz9",
                                                     data,
                                                     &abeoz9_chip_info,
                                                     NULL);
        if (IS_ERR(data->hwmon_dev)) {
                dev_warn(dev, "unable to register hwmon device %ld\n",
                         PTR_ERR(data->hwmon_dev));
        }
}

#else

static void abeoz9_hwmon_register(struct device *dev,
                                  struct abeoz9_rtc_data *data)
{
}

#endif

static int abeoz9_probe(struct i2c_client *client)
{
        struct abeoz9_rtc_data *data = NULL;
        struct device *dev = &client->dev;
        struct regmap *regmap;
        int ret;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
                                     I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_I2C_BLOCK))
                return -ENODEV;

        regmap = devm_regmap_init_i2c(client, &abeoz9_rtc_regmap_config);
        if (IS_ERR(regmap)) {
                ret = PTR_ERR(regmap);
                dev_err(dev, "regmap allocation failed: %d\n", ret);
                return ret;
        }

        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->regmap = regmap;
        dev_set_drvdata(dev, data);

        ret = abeoz9_rtc_setup(dev, client->dev.of_node);
        if (ret)
                return ret;

        data->rtc = devm_rtc_allocate_device(dev);
        ret = PTR_ERR_OR_ZERO(data->rtc);
        if (ret)
                return ret;

        data->rtc->ops = &rtc_ops;
        data->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        data->rtc->range_max = RTC_TIMESTAMP_END_2099;
        clear_bit(RTC_FEATURE_ALARM, data->rtc->features);

        if (client->irq > 0) {
                unsigned long irqflags = IRQF_TRIGGER_LOW;

                if (dev_fwnode(&client->dev))
                        irqflags = 0;

                ret = devm_request_threaded_irq(dev, client->irq, NULL,
                                                abeoz9_rtc_irq,
                                                irqflags | IRQF_ONESHOT,
                                                dev_name(dev), dev);
                if (ret) {
                        dev_err(dev, "failed to request alarm irq\n");
                        return ret;
                }
        } else {
                clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, data->rtc->features);
        }

        if (client->irq > 0 || device_property_read_bool(dev, "wakeup-source")) {
                ret = device_init_wakeup(dev, true);
                set_bit(RTC_FEATURE_ALARM, data->rtc->features);
        }

        ret = devm_rtc_register_device(data->rtc);
        if (ret)
                return ret;

        abeoz9_hwmon_register(dev, data);
        return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id abeoz9_dt_match[] = {
        { .compatible = "abracon,abeoz9" },
        { },
};
MODULE_DEVICE_TABLE(of, abeoz9_dt_match);
#endif

static const struct i2c_device_id abeoz9_id[] = {
        { "abeoz9" },
        { }
};

static struct i2c_driver abeoz9_driver = {
        .driver = {
                .name = "rtc-ab-eoz9",
                .of_match_table = of_match_ptr(abeoz9_dt_match),
        },
        .probe = abeoz9_probe,
        .id_table = abeoz9_id,
};

module_i2c_driver(abeoz9_driver);

MODULE_AUTHOR("Artem Panfilov <panfilov.artyom@gmail.com>");
MODULE_DESCRIPTION("Abracon AB-RTCMC-32.768kHz-EOZ9 RTC driver");
MODULE_LICENSE("GPL");