// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * RTC client/driver for the Maxim/Dallas DS3232/DS3234 Real-Time Clock
 *
 * Copyright (C) 2009-2011 Freescale Semiconductor.
 * Author: Jack Lan <jack.lan@freescale.com>
 * Copyright (C) 2008 MIMOMax Wireless Ltd.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/spi/spi.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/slab.h>
#include <linux/regmap.h>
#include <linux/hwmon.h>

#define DS3232_REG_SECONDS      0x00
#define DS3232_REG_MINUTES      0x01
#define DS3232_REG_HOURS        0x02
#define DS3232_REG_AMPM         0x02
#define DS3232_REG_DAY          0x03
#define DS3232_REG_DATE         0x04
#define DS3232_REG_MONTH        0x05
#define DS3232_REG_CENTURY      0x05
#define DS3232_REG_YEAR         0x06
#define DS3232_REG_ALARM1       0x07       /* Alarm 1 BASE */
#define DS3232_REG_ALARM2       0x0B       /* Alarm 2 BASE */
#define DS3232_REG_CR           0x0E       /* Control register */
#       define DS3232_REG_CR_nEOSC   0x80
#       define DS3232_REG_CR_INTCN   0x04
#       define DS3232_REG_CR_A2IE    0x02
#       define DS3232_REG_CR_A1IE    0x01

#define DS3232_REG_SR           0x0F       /* control/status register */
#       define DS3232_REG_SR_OSF     0x80
#       define DS3232_REG_SR_BSY     0x04
#       define DS3232_REG_SR_A2F     0x02
#       define DS3232_REG_SR_A1F     0x01

#define DS3232_REG_TEMPERATURE  0x11
#define DS3232_REG_SRAM_START   0x14
#define DS3232_REG_SRAM_END     0xFF

#define DS3232_REG_SRAM_SIZE    236

struct ds3232 {
        struct device *dev;
        struct regmap *regmap;
        int irq;
        struct rtc_device *rtc;

        bool suspended;
};

static int ds3232_check_rtc_status(struct device *dev)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int ret = 0;
        int control, stat;

        ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
        if (ret)
                return ret;

        if (stat & DS3232_REG_SR_OSF)
                dev_warn(dev,
                                "oscillator discontinuity flagged, "
                                "time unreliable\n");

        stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);

        ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
        if (ret)
                return ret;

        /* If the alarm is pending, clear it before requesting
         * the interrupt, so an interrupt event isn't reported
         * before everything is initialized.
         */

        ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
        if (ret)
                return ret;

        control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
        control |= DS3232_REG_CR_INTCN;

        return regmap_write(ds3232->regmap, DS3232_REG_CR, control);
}

static int ds3232_read_time(struct device *dev, struct rtc_time *time)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int ret;
        u8 buf[7];
        unsigned int year, month, day, hour, minute, second;
        unsigned int week, twelve_hr, am_pm;
        unsigned int century, add_century = 0;

        ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
        if (ret)
                return ret;

        second = buf[0];
        minute = buf[1];
        hour = buf[2];
        week = buf[3];
        day = buf[4];
        month = buf[5];
        year = buf[6];

        /* Extract additional information for AM/PM and century */

        twelve_hr = hour & 0x40;
        am_pm = hour & 0x20;
        century = month & 0x80;

        /* Write to rtc_time structure */

        time->tm_sec = bcd2bin(second);
        time->tm_min = bcd2bin(minute);
        if (twelve_hr) {
                /* Convert to 24 hr */
                if (am_pm)
                        time->tm_hour = bcd2bin(hour & 0x1F) + 12;
                else
                        time->tm_hour = bcd2bin(hour & 0x1F);
        } else {
                time->tm_hour = bcd2bin(hour);
        }

        /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
        time->tm_wday = bcd2bin(week) - 1;
        time->tm_mday = bcd2bin(day);
        /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
        time->tm_mon = bcd2bin(month & 0x7F) - 1;
        if (century)
                add_century = 100;

        time->tm_year = bcd2bin(year) + add_century;

        return 0;
}

static int ds3232_set_time(struct device *dev, struct rtc_time *time)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        u8 buf[7];

        /* Extract time from rtc_time and load into ds3232*/

        buf[0] = bin2bcd(time->tm_sec);
        buf[1] = bin2bcd(time->tm_min);
        buf[2] = bin2bcd(time->tm_hour);
        /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
        buf[3] = bin2bcd(time->tm_wday + 1);
        buf[4] = bin2bcd(time->tm_mday); /* Date */
        /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
        buf[5] = bin2bcd(time->tm_mon + 1);
        if (time->tm_year >= 100) {
                buf[5] |= 0x80;
                buf[6] = bin2bcd(time->tm_year - 100);
        } else {
                buf[6] = bin2bcd(time->tm_year);
        }

        return regmap_bulk_write(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
}

/*
 * DS3232 has two alarm, we only use alarm1
 * According to linux specification, only support one-shot alarm
 * no periodic alarm mode
 */
static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int control, stat;
        int ret;
        u8 buf[4];

        ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
        if (ret)
                goto out;
        ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
        if (ret)
                goto out;
        ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
        if (ret)
                goto out;

        alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
        alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
        alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
        alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);

        alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
        alarm->pending = !!(stat & DS3232_REG_SR_A1F);

        ret = 0;
out:
        return ret;
}

/*
 * linux rtc-module does not support wday alarm
 * and only 24h time mode supported indeed
 */
static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int control, stat;
        int ret;
        u8 buf[4];

        if (ds3232->irq <= 0)
                return -EINVAL;

        buf[0] = bin2bcd(alarm->time.tm_sec);
        buf[1] = bin2bcd(alarm->time.tm_min);
        buf[2] = bin2bcd(alarm->time.tm_hour);
        buf[3] = bin2bcd(alarm->time.tm_mday);

        /* clear alarm interrupt enable bit */
        ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
        if (ret)
                goto out;
        control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
        ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
        if (ret)
                goto out;

        /* clear any pending alarm flag */
        ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
        if (ret)
                goto out;
        stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
        ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
        if (ret)
                goto out;

        ret = regmap_bulk_write(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
        if (ret)
                goto out;

        if (alarm->enabled) {
                control |= DS3232_REG_CR_A1IE;
                ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
        }
out:
        return ret;
}

static int ds3232_update_alarm(struct device *dev, unsigned int enabled)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int control;
        int ret;

        ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
        if (ret)
                return ret;

        if (enabled)
                /* enable alarm1 interrupt */
                control |= DS3232_REG_CR_A1IE;
        else
                /* disable alarm1 interrupt */
                control &= ~(DS3232_REG_CR_A1IE);
        ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);

        return ret;
}

/*
 * Temperature sensor support for ds3232/ds3234 devices.
 * A user-initiated temperature conversion is not started by this function,
 * so the temperature is updated once every 64 seconds.
 */
static int ds3232_hwmon_read_temp(struct device *dev, long int *mC)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        u8 temp_buf[2];
        s16 temp;
        int ret;

        ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_TEMPERATURE, temp_buf,
                               sizeof(temp_buf));
        if (ret < 0)
                return ret;

        /*
         * Temperature is represented as a 10-bit code with a resolution of
         * 0.25 degree celsius and encoded in two's complement format.
         */
        temp = (temp_buf[0] << 8) | temp_buf[1];
        temp >>= 6;
        *mC = temp * 250;

        return 0;
}

static umode_t ds3232_hwmon_is_visible(const void *data,
                                       enum hwmon_sensor_types type,
                                       u32 attr, int channel)
{
        if (type != hwmon_temp)
                return 0;

        switch (attr) {
        case hwmon_temp_input:
                return 0444;
        default:
                return 0;
        }
}

static int ds3232_hwmon_read(struct device *dev,
                             enum hwmon_sensor_types type,
                             u32 attr, int channel, long *temp)
{
        int err;

        switch (attr) {
        case hwmon_temp_input:
                err = ds3232_hwmon_read_temp(dev, temp);
                break;
        default:
                err = -EOPNOTSUPP;
                break;
        }

        return err;
}

static const struct hwmon_channel_info * const ds3232_hwmon_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
        NULL
};

static const struct hwmon_ops ds3232_hwmon_hwmon_ops = {
        .is_visible = ds3232_hwmon_is_visible,
        .read = ds3232_hwmon_read,
};

static const struct hwmon_chip_info ds3232_hwmon_chip_info = {
        .ops = &ds3232_hwmon_hwmon_ops,
        .info = ds3232_hwmon_info,
};

static void ds3232_hwmon_register(struct device *dev, const char *name)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        struct device *hwmon_dev;

        if (!IS_ENABLED(CONFIG_RTC_DRV_DS3232_HWMON))
                return;

        hwmon_dev = devm_hwmon_device_register_with_info(dev, name, ds3232,
                                                        &ds3232_hwmon_chip_info,
                                                        NULL);
        if (IS_ERR(hwmon_dev)) {
                dev_err(dev, "unable to register hwmon device %ld\n",
                        PTR_ERR(hwmon_dev));
        }
}

static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);

        if (ds3232->irq <= 0)
                return -EINVAL;

        return ds3232_update_alarm(dev, enabled);
}

static irqreturn_t ds3232_irq(int irq, void *dev_id)
{
        struct device *dev = dev_id;
        struct ds3232 *ds3232 = dev_get_drvdata(dev);
        int ret;
        int stat, control;

        rtc_lock(ds3232->rtc);

        ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
        if (ret)
                goto unlock;

        if (stat & DS3232_REG_SR_A1F) {
                ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
                if (ret) {
                        dev_warn(ds3232->dev,
                                 "Read Control Register error %d\n", ret);
                } else {
                        /* disable alarm1 interrupt */
                        control &= ~(DS3232_REG_CR_A1IE);
                        ret = regmap_write(ds3232->regmap, DS3232_REG_CR,
                                           control);
                        if (ret) {
                                dev_warn(ds3232->dev,
                                         "Write Control Register error %d\n",
                                         ret);
                                goto unlock;
                        }

                        /* clear the alarm pend flag */
                        stat &= ~DS3232_REG_SR_A1F;
                        ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
                        if (ret) {
                                dev_warn(ds3232->dev,
                                         "Write Status Register error %d\n",
                                         ret);
                                goto unlock;
                        }

                        rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
                }
        }

unlock:
        rtc_unlock(ds3232->rtc);

        return IRQ_HANDLED;
}

static const struct rtc_class_ops ds3232_rtc_ops = {
        .read_time = ds3232_read_time,
        .set_time = ds3232_set_time,
        .read_alarm = ds3232_read_alarm,
        .set_alarm = ds3232_set_alarm,
        .alarm_irq_enable = ds3232_alarm_irq_enable,
};

static int ds3232_nvmem_read(void *priv, unsigned int offset, void *val,
                             size_t bytes)
{
        struct regmap *ds3232_regmap = (struct regmap *)priv;

        return regmap_bulk_read(ds3232_regmap, DS3232_REG_SRAM_START + offset,
                                val, bytes);
}

static int ds3232_nvmem_write(void *priv, unsigned int offset, void *val,
                              size_t bytes)
{
        struct regmap *ds3232_regmap = (struct regmap *)priv;

        return regmap_bulk_write(ds3232_regmap, DS3232_REG_SRAM_START + offset,
                                 val, bytes);
}

static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
                        const char *name)
{
        struct ds3232 *ds3232;
        int ret;
        struct nvmem_config nvmem_cfg = {
                .name = "ds3232_sram",
                .stride = 1,
                .size = DS3232_REG_SRAM_SIZE,
                .word_size = 1,
                .reg_read = ds3232_nvmem_read,
                .reg_write = ds3232_nvmem_write,
                .priv = regmap,
                .type = NVMEM_TYPE_BATTERY_BACKED
        };

        ds3232 = devm_kzalloc(dev, sizeof(*ds3232), GFP_KERNEL);
        if (!ds3232)
                return -ENOMEM;

        ds3232->regmap = regmap;
        ds3232->irq = irq;
        ds3232->dev = dev;
        dev_set_drvdata(dev, ds3232);

        ret = ds3232_check_rtc_status(dev);
        if (ret)
                return ret;

        if (ds3232->irq > 0)
                device_init_wakeup(dev, true);

        ds3232_hwmon_register(dev, name);

        ds3232->rtc = devm_rtc_device_register(dev, name, &ds3232_rtc_ops,
                                                THIS_MODULE);
        if (IS_ERR(ds3232->rtc))
                return PTR_ERR(ds3232->rtc);

        ret = devm_rtc_nvmem_register(ds3232->rtc, &nvmem_cfg);
        if(ret)
                return ret;

        if (ds3232->irq > 0) {
                ret = devm_request_threaded_irq(dev, ds3232->irq, NULL,
                                                ds3232_irq,
                                                IRQF_SHARED | IRQF_ONESHOT,
                                                name, dev);
                if (ret) {
                        device_set_wakeup_capable(dev, 0);
                        ds3232->irq = 0;
                        dev_err(dev, "unable to request IRQ\n");
                }
        }

        return 0;
}

#if IS_ENABLED(CONFIG_I2C)

#ifdef CONFIG_PM_SLEEP
static int ds3232_suspend(struct device *dev)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);

        if (device_may_wakeup(dev)) {
                if (enable_irq_wake(ds3232->irq))
                        dev_warn_once(dev, "Cannot set wakeup source\n");
        }

        return 0;
}

static int ds3232_resume(struct device *dev)
{
        struct ds3232 *ds3232 = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                disable_irq_wake(ds3232->irq);

        return 0;
}
#endif

static const struct dev_pm_ops ds3232_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
};

static int ds3232_i2c_probe(struct i2c_client *client)
{
        struct regmap *regmap;
        static const struct regmap_config config = {
                .reg_bits = 8,
                .val_bits = 8,
                .max_register = DS3232_REG_SRAM_END,
        };

        regmap = devm_regmap_init_i2c(client, &config);
        if (IS_ERR(regmap)) {
                dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
                        __func__, PTR_ERR(regmap));
                return PTR_ERR(regmap);
        }

        return ds3232_probe(&client->dev, regmap, client->irq, client->name);
}

static const struct i2c_device_id ds3232_id[] = {
        { "ds3232" },
        { }
};
MODULE_DEVICE_TABLE(i2c, ds3232_id);

static const  __maybe_unused struct of_device_id ds3232_of_match[] = {
        { .compatible = "dallas,ds3232" },
        { }
};
MODULE_DEVICE_TABLE(of, ds3232_of_match);

static struct i2c_driver ds3232_driver = {
        .driver = {
                .name = "rtc-ds3232",
                .of_match_table = of_match_ptr(ds3232_of_match),
                .pm     = &ds3232_pm_ops,
        },
        .probe = ds3232_i2c_probe,
        .id_table = ds3232_id,
};

static int ds3232_register_driver(void)
{
        return i2c_add_driver(&ds3232_driver);
}

static void ds3232_unregister_driver(void)
{
        i2c_del_driver(&ds3232_driver);
}

#else

static int ds3232_register_driver(void)
{
        return 0;
}

static void ds3232_unregister_driver(void)
{
}

#endif

#if IS_ENABLED(CONFIG_SPI_MASTER)

static int ds3234_probe(struct spi_device *spi)
{
        int res;
        unsigned int tmp;
        static const struct regmap_config config = {
                .reg_bits = 8,
                .val_bits = 8,
                .max_register = DS3232_REG_SRAM_END,
                .write_flag_mask = 0x80,
        };
        struct regmap *regmap;

        regmap = devm_regmap_init_spi(spi, &config);
        if (IS_ERR(regmap)) {
                dev_err(&spi->dev, "%s: regmap allocation failed: %ld\n",
                        __func__, PTR_ERR(regmap));
                return PTR_ERR(regmap);
        }

        spi->mode = SPI_MODE_3;
        spi->bits_per_word = 8;
        spi_setup(spi);

        res = regmap_read(regmap, DS3232_REG_SECONDS, &tmp);
        if (res)
                return res;

        /* Control settings
         *
         * CONTROL_REG
         * BIT 7        6       5       4       3       2       1       0
         *     EOSC     BBSQW   CONV    RS2     RS1     INTCN   A2IE    A1IE
         *
         *     0        0       0       1       1       1       0       0
         *
         * CONTROL_STAT_REG
         * BIT 7        6       5       4       3       2       1       0
         *     OSF      BB32kHz CRATE1  CRATE0  EN32kHz BSY     A2F     A1F
         *
         *     1        0       0       0       1       0       0       0
         */
        res = regmap_read(regmap, DS3232_REG_CR, &tmp);
        if (res)
                return res;
        res = regmap_write(regmap, DS3232_REG_CR, tmp & 0x1c);
        if (res)
                return res;

        res = regmap_read(regmap, DS3232_REG_SR, &tmp);
        if (res)
                return res;
        res = regmap_write(regmap, DS3232_REG_SR, tmp & 0x88);
        if (res)
                return res;

        /* Print our settings */
        res = regmap_read(regmap, DS3232_REG_CR, &tmp);
        if (res)
                return res;
        dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);

        res = regmap_read(regmap, DS3232_REG_SR, &tmp);
        if (res)
                return res;
        dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);

        return ds3232_probe(&spi->dev, regmap, spi->irq, "ds3234");
}

static struct spi_driver ds3234_driver = {
        .driver = {
                .name    = "ds3234",
        },
        .probe   = ds3234_probe,
};

static int ds3234_register_driver(void)
{
        return spi_register_driver(&ds3234_driver);
}

static void ds3234_unregister_driver(void)
{
        spi_unregister_driver(&ds3234_driver);
}

#else

static int ds3234_register_driver(void)
{
        return 0;
}

static void ds3234_unregister_driver(void)
{
}

#endif

static int __init ds323x_init(void)
{
        int ret;

        ret = ds3232_register_driver();
        if (ret) {
                pr_err("Failed to register ds3232 driver: %d\n", ret);
                return ret;
        }

        ret = ds3234_register_driver();
        if (ret) {
                pr_err("Failed to register ds3234 driver: %d\n", ret);
                ds3232_unregister_driver();
        }

        return ret;
}
module_init(ds323x_init)

static void __exit ds323x_exit(void)
{
        ds3234_unregister_driver();
        ds3232_unregister_driver();
}
module_exit(ds323x_exit)

MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
MODULE_DESCRIPTION("Maxim/Dallas DS3232/DS3234 RTC Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:ds3234");