// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for Epson's RTC module RX-8025 SA/NB
 *
 * Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
 *
 * Copyright (C) 2005 by Digi International Inc.
 * All rights reserved.
 *
 * Modified by fengjh at rising.com.cn
 * <lm-sensors@lm-sensors.org>
 * 2006.11
 *
 * Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
 * Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
 * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.com>
 */
#include <linux/bcd.h>
#include <linux/bitops.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/kstrtox.h>
#include <linux/module.h>
#include <linux/rtc.h>

/* Register definitions */
#define RX8025_REG_SEC          0x00
#define RX8025_REG_MIN          0x01
#define RX8025_REG_HOUR         0x02
#define RX8025_REG_WDAY         0x03
#define RX8025_REG_MDAY         0x04
#define RX8025_REG_MONTH        0x05
#define RX8025_REG_YEAR         0x06
#define RX8025_REG_DIGOFF       0x07
#define RX8025_REG_ALWMIN       0x08
#define RX8025_REG_ALWHOUR      0x09
#define RX8025_REG_ALWWDAY      0x0a
#define RX8025_REG_ALDMIN       0x0b
#define RX8025_REG_ALDHOUR      0x0c
/* 0x0d is reserved */
#define RX8025_REG_CTRL1        0x0e
#define RX8025_REG_CTRL2        0x0f

#define RX8025_BIT_CTRL1_CT     (7 << 0)
/* 1 Hz periodic level irq */
#define RX8025_BIT_CTRL1_CT_1HZ 4
#define RX8025_BIT_CTRL1_TEST   BIT(3)
#define RX8025_BIT_CTRL1_1224   BIT(5)
#define RX8025_BIT_CTRL1_DALE   BIT(6)
#define RX8025_BIT_CTRL1_WALE   BIT(7)

#define RX8025_BIT_CTRL2_DAFG   BIT(0)
#define RX8025_BIT_CTRL2_WAFG   BIT(1)
#define RX8025_BIT_CTRL2_CTFG   BIT(2)
#define RX8025_BIT_CTRL2_PON    BIT(4)
#define RX8025_BIT_CTRL2_XST    BIT(5)
#define RX8025_BIT_CTRL2_VDET   BIT(6)

#define RX8035_BIT_HOUR_1224    BIT(7)

/* Clock precision adjustment */
#define RX8025_ADJ_RESOLUTION   3050 /* in ppb */
#define RX8025_ADJ_DATA_MAX     62
#define RX8025_ADJ_DATA_MIN     -62

enum rx_model {
        model_rx_unknown,
        model_rx_8025,
        model_rx_8035,
        model_last
};

static const struct i2c_device_id rx8025_id[] = {
        { "rx8025", model_rx_8025 },
        { "rx8035", model_rx_8035 },
        { }
};
MODULE_DEVICE_TABLE(i2c, rx8025_id);

struct rx8025_data {
        struct rtc_device *rtc;
        enum rx_model model;
        u8 ctrl1;
        int is_24;
};

static s32 rx8025_read_reg(const struct i2c_client *client, u8 number)
{
        return i2c_smbus_read_byte_data(client, number << 4);
}

static int rx8025_read_regs(const struct i2c_client *client,
                            u8 number, u8 length, u8 *values)
{
        int ret = i2c_smbus_read_i2c_block_data(client, number << 4, length,
                                                values);
        if (ret != length)
                return ret < 0 ? ret : -EIO;

        return 0;
}

static s32 rx8025_write_reg(const struct i2c_client *client, u8 number,
                            u8 value)
{
        return i2c_smbus_write_byte_data(client, number << 4, value);
}

static s32 rx8025_write_regs(const struct i2c_client *client,
                             u8 number, u8 length, const u8 *values)
{
        return i2c_smbus_write_i2c_block_data(client, number << 4,
                                              length, values);
}

static int rx8025_is_osc_stopped(enum rx_model model, int ctrl2)
{
        int xstp = ctrl2 & RX8025_BIT_CTRL2_XST;
        /* XSTP bit has different polarity on RX-8025 vs RX-8035.
         * RX-8025: 0 == oscillator stopped
         * RX-8035: 1 == oscillator stopped
         */

        if (model == model_rx_8025)
                xstp = !xstp;

        return xstp;
}

static int rx8025_check_validity(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *drvdata = dev_get_drvdata(dev);
        int ctrl2;
        int xstp;

        ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
        if (ctrl2 < 0)
                return ctrl2;

        if (ctrl2 & RX8025_BIT_CTRL2_VDET)
                dev_warn(dev, "power voltage drop detected\n");

        if (ctrl2 & RX8025_BIT_CTRL2_PON) {
                dev_warn(dev, "power-on reset detected, date is invalid\n");
                return -EINVAL;
        }

        xstp = rx8025_is_osc_stopped(drvdata->model, ctrl2);
        if (xstp) {
                dev_warn(dev, "crystal stopped, date is invalid\n");
                return -EINVAL;
        }

        return 0;
}

static int rx8025_reset_validity(struct i2c_client *client)
{
        struct rx8025_data *drvdata = i2c_get_clientdata(client);
        int ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);

        if (ctrl2 < 0)
                return ctrl2;

        ctrl2 &= ~(RX8025_BIT_CTRL2_PON | RX8025_BIT_CTRL2_VDET);

        if (drvdata->model == model_rx_8025)
                ctrl2 |= RX8025_BIT_CTRL2_XST;
        else
                ctrl2 &= ~(RX8025_BIT_CTRL2_XST);

        return rx8025_write_reg(client, RX8025_REG_CTRL2,
                                ctrl2);
}

static irqreturn_t rx8025_handle_irq(int irq, void *dev_id)
{
        struct i2c_client *client = dev_id;
        struct rx8025_data *rx8025 = i2c_get_clientdata(client);
        int status, xstp;

        rtc_lock(rx8025->rtc);
        status = rx8025_read_reg(client, RX8025_REG_CTRL2);
        if (status < 0)
                goto out;

        xstp = rx8025_is_osc_stopped(rx8025->model, status);
        if (xstp)
                dev_warn(&client->dev, "Oscillation stop was detected,"
                         "you may have to readjust the clock\n");

        if (status & RX8025_BIT_CTRL2_CTFG) {
                /* periodic */
                status &= ~RX8025_BIT_CTRL2_CTFG;
                rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
        }

        if (status & RX8025_BIT_CTRL2_DAFG) {
                /* alarm */
                status &= RX8025_BIT_CTRL2_DAFG;
                if (rx8025_write_reg(client, RX8025_REG_CTRL1,
                                     rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
                        goto out;
                rtc_update_irq(rx8025->rtc, 1, RTC_AF | RTC_IRQF);
        }

out:
        rtc_unlock(rx8025->rtc);

        return IRQ_HANDLED;
}

static int rx8025_get_time(struct device *dev, struct rtc_time *dt)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *rx8025 = dev_get_drvdata(dev);
        u8 date[7];
        int err;

        err = rx8025_check_validity(dev);
        if (err)
                return err;

        err = rx8025_read_regs(client, RX8025_REG_SEC, 7, date);
        if (err)
                return err;

        dev_dbg(dev, "%s: read %7ph\n", __func__, date);

        dt->tm_sec = bcd2bin(date[RX8025_REG_SEC] & 0x7f);
        dt->tm_min = bcd2bin(date[RX8025_REG_MIN] & 0x7f);
        if (rx8025->is_24)
                dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x3f);
        else
                dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x1f) % 12
                        + (date[RX8025_REG_HOUR] & 0x20 ? 12 : 0);

        dt->tm_mday = bcd2bin(date[RX8025_REG_MDAY] & 0x3f);
        dt->tm_mon = bcd2bin(date[RX8025_REG_MONTH] & 0x1f) - 1;
        dt->tm_year = bcd2bin(date[RX8025_REG_YEAR]) + 100;

        dev_dbg(dev, "%s: date %ptRr\n", __func__, dt);

        return 0;
}

static int rx8025_set_time(struct device *dev, struct rtc_time *dt)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *rx8025 = dev_get_drvdata(dev);
        u8 date[7];
        int ret;

        /*
         * Here the read-only bits are written as "0".  I'm not sure if that
         * is sound.
         */
        date[RX8025_REG_SEC] = bin2bcd(dt->tm_sec);
        date[RX8025_REG_MIN] = bin2bcd(dt->tm_min);
        if (rx8025->is_24)
                date[RX8025_REG_HOUR] = bin2bcd(dt->tm_hour);
        else
                date[RX8025_REG_HOUR] = (dt->tm_hour >= 12 ? 0x20 : 0)
                        | bin2bcd((dt->tm_hour + 11) % 12 + 1);

        date[RX8025_REG_WDAY] = bin2bcd(dt->tm_wday);
        date[RX8025_REG_MDAY] = bin2bcd(dt->tm_mday);
        date[RX8025_REG_MONTH] = bin2bcd(dt->tm_mon + 1);
        date[RX8025_REG_YEAR] = bin2bcd(dt->tm_year - 100);

        dev_dbg(dev, "%s: write %7ph\n", __func__, date);

        ret = rx8025_write_regs(client, RX8025_REG_SEC, 7, date);
        if (ret < 0)
                return ret;

        return rx8025_reset_validity(client);
}

static int rx8025_init_client(struct i2c_client *client)
{
        struct rx8025_data *rx8025 = i2c_get_clientdata(client);
        u8 ctrl[2], ctrl2;
        int need_clear = 0;
        int hour_reg;
        int err;

        err = rx8025_read_regs(client, RX8025_REG_CTRL1, 2, ctrl);
        if (err)
                goto out;

        /* Keep test bit zero ! */
        rx8025->ctrl1 = ctrl[0] & ~RX8025_BIT_CTRL1_TEST;

        if (ctrl[1] & (RX8025_BIT_CTRL2_DAFG | RX8025_BIT_CTRL2_WAFG)) {
                dev_warn(&client->dev, "Alarm was detected\n");
                need_clear = 1;
        }

        if (ctrl[1] & RX8025_BIT_CTRL2_CTFG)
                need_clear = 1;

        if (need_clear) {
                ctrl2 = ctrl[1];
                ctrl2 &= ~(RX8025_BIT_CTRL2_CTFG | RX8025_BIT_CTRL2_WAFG |
                           RX8025_BIT_CTRL2_DAFG);

                err = rx8025_write_reg(client, RX8025_REG_CTRL2, ctrl2);
        }

        if (rx8025->model == model_rx_8035) {
                /* In RX-8035, 12/24 flag is in the hour register */
                hour_reg = rx8025_read_reg(client, RX8025_REG_HOUR);
                if (hour_reg < 0)
                        return hour_reg;
                rx8025->is_24 = (hour_reg & RX8035_BIT_HOUR_1224);
        } else {
                rx8025->is_24 = (ctrl[0] & RX8025_BIT_CTRL1_1224);
        }
out:
        return err;
}

/* Alarm support */
static int rx8025_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *rx8025 = dev_get_drvdata(dev);
        u8 ald[2];
        int ctrl2, err;

        err = rx8025_read_regs(client, RX8025_REG_ALDMIN, 2, ald);
        if (err)
                return err;

        ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
        if (ctrl2 < 0)
                return ctrl2;

        dev_dbg(dev, "%s: read alarm 0x%02x 0x%02x ctrl2 %02x\n",
                __func__, ald[0], ald[1], ctrl2);

        /* Hardware alarms precision is 1 minute! */
        t->time.tm_sec = 0;
        t->time.tm_min = bcd2bin(ald[0] & 0x7f);
        if (rx8025->is_24)
                t->time.tm_hour = bcd2bin(ald[1] & 0x3f);
        else
                t->time.tm_hour = bcd2bin(ald[1] & 0x1f) % 12
                        + (ald[1] & 0x20 ? 12 : 0);

        dev_dbg(dev, "%s: date: %ptRr\n", __func__, &t->time);
        t->enabled = !!(rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE);
        t->pending = (ctrl2 & RX8025_BIT_CTRL2_DAFG) && t->enabled;

        return err;
}

static int rx8025_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *rx8025 = dev_get_drvdata(dev);
        u8 ald[2];
        int err;

        ald[0] = bin2bcd(t->time.tm_min);
        if (rx8025->is_24)
                ald[1] = bin2bcd(t->time.tm_hour);
        else
                ald[1] = (t->time.tm_hour >= 12 ? 0x20 : 0)
                        | bin2bcd((t->time.tm_hour + 11) % 12 + 1);

        dev_dbg(dev, "%s: write 0x%02x 0x%02x\n", __func__, ald[0], ald[1]);

        if (rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE) {
                rx8025->ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
                err = rx8025_write_reg(client, RX8025_REG_CTRL1,
                                       rx8025->ctrl1);
                if (err)
                        return err;
        }
        err = rx8025_write_regs(client, RX8025_REG_ALDMIN, 2, ald);
        if (err)
                return err;

        if (t->enabled) {
                rx8025->ctrl1 |= RX8025_BIT_CTRL1_DALE;
                err = rx8025_write_reg(client, RX8025_REG_CTRL1,
                                       rx8025->ctrl1);
                if (err)
                        return err;
        }

        return 0;
}

static int rx8025_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rx8025_data *rx8025 = dev_get_drvdata(dev);
        u8 ctrl1;
        int err;

        ctrl1 = rx8025->ctrl1;
        if (enabled)
                ctrl1 |= RX8025_BIT_CTRL1_DALE;
        else
                ctrl1 &= ~RX8025_BIT_CTRL1_DALE;

        if (ctrl1 != rx8025->ctrl1) {
                rx8025->ctrl1 = ctrl1;
                err = rx8025_write_reg(client, RX8025_REG_CTRL1,
                                       rx8025->ctrl1);
                if (err)
                        return err;
        }
        return 0;
}

/*
 * According to the RX8025 SA/NB application manual the frequency and
 * temperature characteristics can be approximated using the following
 * equation:
 *
 *   df = a * (ut - t)**2
 *
 *   df: Frequency deviation in any temperature
 *   a : Coefficient = (-35 +-5) * 10**-9
 *   ut: Ultimate temperature in degree = +25 +-5 degree
 *   t : Any temperature in degree
 */
static int rx8025_read_offset(struct device *dev, long *offset)
{
        struct i2c_client *client = to_i2c_client(dev);
        int digoff;

        digoff = rx8025_read_reg(client, RX8025_REG_DIGOFF);
        if (digoff < 0)
                return digoff;

        *offset = digoff >= 64 ? digoff - 128 : digoff;
        if (*offset > 0)
                (*offset)--;
        *offset *= RX8025_ADJ_RESOLUTION;

        return 0;
}

static int rx8025_set_offset(struct device *dev, long offset)
{
        struct i2c_client *client = to_i2c_client(dev);
        u8 digoff;

        offset /= RX8025_ADJ_RESOLUTION;
        if (offset > RX8025_ADJ_DATA_MAX)
                offset = RX8025_ADJ_DATA_MAX;
        else if (offset < RX8025_ADJ_DATA_MIN)
                offset = RX8025_ADJ_DATA_MIN;
        else if (offset > 0)
                offset++;
        else if (offset < 0)
                offset += 128;
        digoff = offset;

        return rx8025_write_reg(client, RX8025_REG_DIGOFF, digoff);
}

static const struct rtc_class_ops rx8025_rtc_ops = {
        .read_time = rx8025_get_time,
        .set_time = rx8025_set_time,
        .read_alarm = rx8025_read_alarm,
        .set_alarm = rx8025_set_alarm,
        .alarm_irq_enable = rx8025_alarm_irq_enable,
        .read_offset = rx8025_read_offset,
        .set_offset = rx8025_set_offset,
};

static ssize_t rx8025_sysfs_show_clock_adjust(struct device *dev,
                                              struct device_attribute *attr,
                                              char *buf)
{
        long adj;
        int err;

        dev_warn_once(dev, "clock_adjust_ppb is deprecated, use offset\n");
        err = rx8025_read_offset(dev, &adj);
        if (err)
                return err;

        return sprintf(buf, "%ld\n", -adj);
}

static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
                                               struct device_attribute *attr,
                                               const char *buf, size_t count)
{
        long adj;
        int err;

        dev_warn_once(dev, "clock_adjust_ppb is deprecated, use offset\n");
        if (kstrtol(buf, 10, &adj) != 0)
                return -EINVAL;

        err = rx8025_set_offset(dev, -adj);

        return err ? err : count;
}

static DEVICE_ATTR(clock_adjust_ppb, S_IRUGO | S_IWUSR,
                   rx8025_sysfs_show_clock_adjust,
                   rx8025_sysfs_store_clock_adjust);

static struct attribute *rx8025_attrs[] = {
        &dev_attr_clock_adjust_ppb.attr,
        NULL
};

static const struct attribute_group rx8025_attr_group = {
        .attrs  = rx8025_attrs,
};

static int rx8025_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_match_id(rx8025_id, client);
        struct i2c_adapter *adapter = client->adapter;
        struct rx8025_data *rx8025;
        int err = 0;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
                                     | I2C_FUNC_SMBUS_I2C_BLOCK)) {
                dev_err(&adapter->dev,
                        "doesn't support required functionality\n");
                return -EIO;
        }

        rx8025 = devm_kzalloc(&client->dev, sizeof(*rx8025), GFP_KERNEL);
        if (!rx8025)
                return -ENOMEM;

        i2c_set_clientdata(client, rx8025);

        if (id)
                rx8025->model = id->driver_data;

        err = rx8025_init_client(client);
        if (err)
                return err;

        rx8025->rtc = devm_rtc_allocate_device(&client->dev);
        if (IS_ERR(rx8025->rtc))
                return PTR_ERR(rx8025->rtc);

        rx8025->rtc->ops = &rx8025_rtc_ops;
        rx8025->rtc->range_min = RTC_TIMESTAMP_BEGIN_1900;
        rx8025->rtc->range_max = RTC_TIMESTAMP_END_2099;

        if (client->irq > 0) {
                dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
                err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
                                                rx8025_handle_irq,
                                                IRQF_ONESHOT,
                                                "rx8025", client);
                if (err)
                        clear_bit(RTC_FEATURE_ALARM, rx8025->rtc->features);
        }

        set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rx8025->rtc->features);
        clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rx8025->rtc->features);

        err = rtc_add_group(rx8025->rtc, &rx8025_attr_group);
        if (err)
                return err;

        return devm_rtc_register_device(rx8025->rtc);
}

static struct i2c_driver rx8025_driver = {
        .driver = {
                .name = "rtc-rx8025",
        },
        .probe          = rx8025_probe,
        .id_table       = rx8025_id,
};

module_i2c_driver(rx8025_driver);

MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
MODULE_DESCRIPTION("RX-8025 SA/NB RTC driver");
MODULE_LICENSE("GPL");