// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2022 Nuvoton Technology Corporation

#include <linux/bcd.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define NCT3018Y_REG_SC         0x00 /* seconds */
#define NCT3018Y_REG_SCA        0x01 /* alarm */
#define NCT3018Y_REG_MN         0x02
#define NCT3018Y_REG_MNA        0x03 /* alarm */
#define NCT3018Y_REG_HR         0x04
#define NCT3018Y_REG_HRA        0x05 /* alarm */
#define NCT3018Y_REG_DW         0x06
#define NCT3018Y_REG_DM         0x07
#define NCT3018Y_REG_MO         0x08
#define NCT3018Y_REG_YR         0x09
#define NCT3018Y_REG_CTRL       0x0A /* timer control */
#define NCT3018Y_REG_ST         0x0B /* status */
#define NCT3018Y_REG_CLKO       0x0C /* clock out */
#define NCT3018Y_REG_PART       0x21 /* part info */

#define NCT3018Y_BIT_AF         BIT(7)
#define NCT3018Y_BIT_ST         BIT(7)
#define NCT3018Y_BIT_DM         BIT(6)
#define NCT3018Y_BIT_HF         BIT(5)
#define NCT3018Y_BIT_DSM        BIT(4)
#define NCT3018Y_BIT_AIE        BIT(3)
#define NCT3018Y_BIT_OFIE       BIT(2)
#define NCT3018Y_BIT_CIE        BIT(1)
#define NCT3018Y_BIT_TWO        BIT(0)

#define NCT3018Y_REG_BAT_MASK           0x07
#define NCT3018Y_REG_CLKO_F_MASK        0x03 /* frequenc mask */
#define NCT3018Y_REG_CLKO_CKE           0x80 /* clock out enabled */
#define NCT3018Y_REG_PART_NCT3018Y      0x02

struct nct3018y {
        struct rtc_device *rtc;
        struct i2c_client *client;
        int part_num;
#ifdef CONFIG_COMMON_CLK
        struct clk_hw clkout_hw;
#endif
};

static int nct3018y_set_alarm_mode(struct i2c_client *client, bool on)
{
        int err, flags;

        dev_dbg(&client->dev, "%s:on:%d\n", __func__, on);

        flags =  i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
        if (flags < 0) {
                dev_dbg(&client->dev,
                        "Failed to read NCT3018Y_REG_CTRL\n");
                return flags;
        }

        if (on)
                flags |= NCT3018Y_BIT_AIE;
        else
                flags &= ~NCT3018Y_BIT_AIE;

        flags |= NCT3018Y_BIT_CIE;
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL\n");
                return err;
        }

        flags =  i2c_smbus_read_byte_data(client, NCT3018Y_REG_ST);
        if (flags < 0) {
                dev_dbg(&client->dev,
                        "Failed to read NCT3018Y_REG_ST\n");
                return flags;
        }

        flags &= ~(NCT3018Y_BIT_AF);
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_ST, flags);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_ST\n");
                return err;
        }

        return 0;
}

static int nct3018y_get_alarm_mode(struct i2c_client *client, unsigned char *alarm_enable,
                                   unsigned char *alarm_flag)
{
        int flags;

        if (alarm_enable) {
                dev_dbg(&client->dev, "%s:NCT3018Y_REG_CTRL\n", __func__);
                flags =  i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
                if (flags < 0)
                        return flags;
                *alarm_enable = flags & NCT3018Y_BIT_AIE;
                dev_dbg(&client->dev, "%s:alarm_enable:%x\n", __func__, *alarm_enable);

        }

        if (alarm_flag) {
                dev_dbg(&client->dev, "%s:NCT3018Y_REG_ST\n", __func__);
                flags =  i2c_smbus_read_byte_data(client, NCT3018Y_REG_ST);
                if (flags < 0)
                        return flags;
                *alarm_flag = flags & NCT3018Y_BIT_AF;
                dev_dbg(&client->dev, "%s:alarm_flag:%x\n", __func__, *alarm_flag);
        }

        return 0;
}

static irqreturn_t nct3018y_irq(int irq, void *dev_id)
{
        struct nct3018y *nct3018y = i2c_get_clientdata(dev_id);
        struct i2c_client *client = nct3018y->client;
        int err;
        unsigned char alarm_flag;
        unsigned char alarm_enable;

        dev_dbg(&client->dev, "%s:irq:%d\n", __func__, irq);
        err = nct3018y_get_alarm_mode(nct3018y->client, &alarm_enable, &alarm_flag);
        if (err)
                return IRQ_NONE;

        if (alarm_flag) {
                dev_dbg(&client->dev, "%s:alarm flag:%x\n",
                        __func__, alarm_flag);
                rtc_update_irq(nct3018y->rtc, 1, RTC_IRQF | RTC_AF);
                nct3018y_set_alarm_mode(nct3018y->client, 0);
                dev_dbg(&client->dev, "%s:IRQ_HANDLED\n", __func__);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/*
 * In the routines that deal directly with the nct3018y hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 */
static int nct3018y_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[10];
        int err;

        err = i2c_smbus_read_i2c_block_data(client, NCT3018Y_REG_ST, 1, buf);
        if (err < 0)
                return err;

        if (!buf[0]) {
                dev_dbg(&client->dev, " voltage <=1.7, date/time is not reliable.\n");
                return -EINVAL;
        }

        err = i2c_smbus_read_i2c_block_data(client, NCT3018Y_REG_SC, sizeof(buf), buf);
        if (err < 0)
                return err;

        tm->tm_sec = bcd2bin(buf[0] & 0x7F);
        tm->tm_min = bcd2bin(buf[2] & 0x7F);
        tm->tm_hour = bcd2bin(buf[4] & 0x3F);
        tm->tm_wday = buf[6] & 0x07;
        tm->tm_mday = bcd2bin(buf[7] & 0x3F);
        tm->tm_mon = bcd2bin(buf[8] & 0x1F) - 1;
        tm->tm_year = bcd2bin(buf[9]) + 100;

        return 0;
}

static int nct3018y_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct nct3018y *nct3018y = dev_get_drvdata(dev);
        unsigned char buf[4] = {0};
        int err, flags;
        int restore_flags = 0;

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
        if (flags < 0) {
                dev_dbg(&client->dev, "Failed to read NCT3018Y_REG_CTRL.\n");
                return flags;
        }

        /* Check and set TWO bit */
        if (nct3018y->part_num == NCT3018Y_REG_PART_NCT3018Y && !(flags & NCT3018Y_BIT_TWO)) {
                restore_flags = 1;
                flags |= NCT3018Y_BIT_TWO;
                err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
                if (err < 0) {
                        dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL.\n");
                        return err;
                }
        }

        buf[0] = bin2bcd(tm->tm_sec);
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_SC, buf[0]);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_SC\n");
                return err;
        }

        buf[0] = bin2bcd(tm->tm_min);
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_MN, buf[0]);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_MN\n");
                return err;
        }

        buf[0] = bin2bcd(tm->tm_hour);
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_HR, buf[0]);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_HR\n");
                return err;
        }

        buf[0] = tm->tm_wday & 0x07;
        buf[1] = bin2bcd(tm->tm_mday);
        buf[2] = bin2bcd(tm->tm_mon + 1);
        buf[3] = bin2bcd(tm->tm_year - 100);
        err = i2c_smbus_write_i2c_block_data(client, NCT3018Y_REG_DW,
                                             sizeof(buf), buf);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write for day and mon and year\n");
                return -EIO;
        }

        /* Restore TWO bit */
        if (restore_flags) {
                if (nct3018y->part_num == NCT3018Y_REG_PART_NCT3018Y)
                        flags &= ~NCT3018Y_BIT_TWO;

                err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
                if (err < 0) {
                        dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL.\n");
                        return err;
                }
        }

        return err;
}

static int nct3018y_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[5];
        int err;

        err = i2c_smbus_read_i2c_block_data(client, NCT3018Y_REG_SCA,
                                            sizeof(buf), buf);
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to read date\n");
                return -EIO;
        }

        dev_dbg(&client->dev, "%s: raw data is sec=%02x, min=%02x hr=%02x\n",
                __func__, buf[0], buf[2], buf[4]);

        tm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
        tm->time.tm_min = bcd2bin(buf[2] & 0x7F);
        tm->time.tm_hour = bcd2bin(buf[4] & 0x3F);

        err = nct3018y_get_alarm_mode(client, &tm->enabled, &tm->pending);
        if (err < 0)
                return err;

        dev_dbg(&client->dev, "%s:s=%d m=%d, hr=%d, enabled=%d, pending=%d\n",
                __func__, tm->time.tm_sec, tm->time.tm_min,
                tm->time.tm_hour, tm->enabled, tm->pending);

        return 0;
}

static int nct3018y_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        int err;

        dev_dbg(dev, "%s, sec=%d, min=%d hour=%d tm->enabled:%d\n",
                __func__, tm->time.tm_sec, tm->time.tm_min, tm->time.tm_hour,
                tm->enabled);

        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_SCA, bin2bcd(tm->time.tm_sec));
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_SCA\n");
                return err;
        }

        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_MNA, bin2bcd(tm->time.tm_min));
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_MNA\n");
                return err;
        }

        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_HRA, bin2bcd(tm->time.tm_hour));
        if (err < 0) {
                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_HRA\n");
                return err;
        }

        return nct3018y_set_alarm_mode(client, tm->enabled);
}

static int nct3018y_irq_enable(struct device *dev, unsigned int enabled)
{
        dev_dbg(dev, "%s: alarm enable=%d\n", __func__, enabled);

        return nct3018y_set_alarm_mode(to_i2c_client(dev), enabled);
}

static int nct3018y_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct i2c_client *client = to_i2c_client(dev);
        int status, flags = 0;

        switch (cmd) {
        case RTC_VL_READ:
                status = i2c_smbus_read_byte_data(client, NCT3018Y_REG_ST);
                if (status < 0)
                        return status;

                if (!(status & NCT3018Y_REG_BAT_MASK))
                        flags |= RTC_VL_DATA_INVALID;

                return put_user(flags, (unsigned int __user *)arg);

        default:
                return -ENOIOCTLCMD;
        }
}

#ifdef CONFIG_COMMON_CLK
/*
 * Handling of the clkout
 */

#define clkout_hw_to_nct3018y(_hw) container_of(_hw, struct nct3018y, clkout_hw)

static const int clkout_rates[] = {
        32768,
        1024,
        32,
        1,
};

static unsigned long nct3018y_clkout_recalc_rate(struct clk_hw *hw,
                                                 unsigned long parent_rate)
{
        struct nct3018y *nct3018y = clkout_hw_to_nct3018y(hw);
        struct i2c_client *client = nct3018y->client;
        int flags;

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CLKO);
        if (flags < 0)
                return 0;

        flags &= NCT3018Y_REG_CLKO_F_MASK;
        return clkout_rates[flags];
}

static int nct3018y_clkout_determine_rate(struct clk_hw *hw,
                                          struct clk_rate_request *req)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
                if (clkout_rates[i] <= req->rate) {
                        req->rate = clkout_rates[i];

                        return 0;
                }

        req->rate = clkout_rates[0];

        return 0;
}

static int nct3018y_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
                                    unsigned long parent_rate)
{
        struct nct3018y *nct3018y = clkout_hw_to_nct3018y(hw);
        struct i2c_client *client = nct3018y->client;
        int i, flags;

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CLKO);
        if (flags < 0)
                return flags;

        for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
                if (clkout_rates[i] == rate) {
                        flags &= ~NCT3018Y_REG_CLKO_F_MASK;
                        flags |= i;
                        return i2c_smbus_write_byte_data(client, NCT3018Y_REG_CLKO, flags);
                }

        return -EINVAL;
}

static int nct3018y_clkout_control(struct clk_hw *hw, bool enable)
{
        struct nct3018y *nct3018y = clkout_hw_to_nct3018y(hw);
        struct i2c_client *client = nct3018y->client;
        int flags;

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CLKO);
        if (flags < 0)
                return flags;

        if (enable)
                flags |= NCT3018Y_REG_CLKO_CKE;
        else
                flags &= ~NCT3018Y_REG_CLKO_CKE;

        return i2c_smbus_write_byte_data(client, NCT3018Y_REG_CLKO, flags);
}

static int nct3018y_clkout_prepare(struct clk_hw *hw)
{
        return nct3018y_clkout_control(hw, 1);
}

static void nct3018y_clkout_unprepare(struct clk_hw *hw)
{
        nct3018y_clkout_control(hw, 0);
}

static int nct3018y_clkout_is_prepared(struct clk_hw *hw)
{
        struct nct3018y *nct3018y = clkout_hw_to_nct3018y(hw);
        struct i2c_client *client = nct3018y->client;
        int flags;

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CLKO);
        if (flags < 0)
                return flags;

        return flags & NCT3018Y_REG_CLKO_CKE;
}

static const struct clk_ops nct3018y_clkout_ops = {
        .prepare = nct3018y_clkout_prepare,
        .unprepare = nct3018y_clkout_unprepare,
        .is_prepared = nct3018y_clkout_is_prepared,
        .recalc_rate = nct3018y_clkout_recalc_rate,
        .determine_rate = nct3018y_clkout_determine_rate,
        .set_rate = nct3018y_clkout_set_rate,
};

static struct clk *nct3018y_clkout_register_clk(struct nct3018y *nct3018y)
{
        struct i2c_client *client = nct3018y->client;
        struct device_node *node = client->dev.of_node;
        struct clk *clk;
        struct clk_init_data init;

        init.name = "nct3018y-clkout";
        init.ops = &nct3018y_clkout_ops;
        init.flags = 0;
        init.parent_names = NULL;
        init.num_parents = 0;
        nct3018y->clkout_hw.init = &init;

        /* optional override of the clockname */
        of_property_read_string(node, "clock-output-names", &init.name);

        /* register the clock */
        clk = devm_clk_register(&client->dev, &nct3018y->clkout_hw);

        if (!IS_ERR(clk))
                of_clk_add_provider(node, of_clk_src_simple_get, clk);

        return clk;
}
#endif

static const struct rtc_class_ops nct3018y_rtc_ops = {
        .read_time      = nct3018y_rtc_read_time,
        .set_time       = nct3018y_rtc_set_time,
        .read_alarm     = nct3018y_rtc_read_alarm,
        .set_alarm      = nct3018y_rtc_set_alarm,
        .alarm_irq_enable = nct3018y_irq_enable,
        .ioctl          = nct3018y_ioctl,
};

static int nct3018y_probe(struct i2c_client *client)
{
        struct nct3018y *nct3018y;
        int err, flags;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
                                     I2C_FUNC_SMBUS_BYTE |
                                     I2C_FUNC_SMBUS_BLOCK_DATA))
                return -ENODEV;

        nct3018y = devm_kzalloc(&client->dev, sizeof(struct nct3018y),
                                GFP_KERNEL);
        if (!nct3018y)
                return -ENOMEM;

        i2c_set_clientdata(client, nct3018y);
        nct3018y->client = client;
        device_set_wakeup_capable(&client->dev, 1);

        flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
        if (flags < 0) {
                dev_dbg(&client->dev, "%s: read error\n", __func__);
                return flags;
        } else if (flags & NCT3018Y_BIT_TWO) {
                dev_dbg(&client->dev, "%s: NCT3018Y_BIT_TWO is set\n", __func__);
        }

        nct3018y->part_num = i2c_smbus_read_byte_data(client, NCT3018Y_REG_PART);
        if (nct3018y->part_num < 0) {
                dev_dbg(&client->dev, "Failed to read NCT3018Y_REG_PART.\n");
                return nct3018y->part_num;
        } else {
                nct3018y->part_num &= 0x03; /* Part number is corresponding to bit 0 and 1 */
                if (nct3018y->part_num == NCT3018Y_REG_PART_NCT3018Y) {
                        flags = NCT3018Y_BIT_HF;
                        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
                        if (err < 0) {
                                dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL.\n");
                                return err;
                        }
                }
        }

        flags = 0;
        err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_ST, flags);
        if (err < 0) {
                dev_dbg(&client->dev, "%s: write error\n", __func__);
                return err;
        }

        nct3018y->rtc = devm_rtc_allocate_device(&client->dev);
        if (IS_ERR(nct3018y->rtc))
                return PTR_ERR(nct3018y->rtc);

        nct3018y->rtc->ops = &nct3018y_rtc_ops;
        nct3018y->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        nct3018y->rtc->range_max = RTC_TIMESTAMP_END_2099;

        if (client->irq > 0) {
                err = devm_request_threaded_irq(&client->dev, client->irq,
                                                NULL, nct3018y_irq,
                                                IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
                                                "nct3018y", client);
                if (err) {
                        dev_dbg(&client->dev, "unable to request IRQ %d\n", client->irq);
                        return err;
                }
        } else {
                clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, nct3018y->rtc->features);
                clear_bit(RTC_FEATURE_ALARM, nct3018y->rtc->features);
        }

#ifdef CONFIG_COMMON_CLK
        /* register clk in common clk framework */
        nct3018y_clkout_register_clk(nct3018y);
#endif

        return devm_rtc_register_device(nct3018y->rtc);
}

static const struct i2c_device_id nct3018y_id[] = {
        { .name = "nct3018y" },
        { }
};
MODULE_DEVICE_TABLE(i2c, nct3018y_id);

static const struct of_device_id nct3018y_of_match[] = {
        { .compatible = "nuvoton,nct3018y" },
        {}
};
MODULE_DEVICE_TABLE(of, nct3018y_of_match);

static struct i2c_driver nct3018y_driver = {
        .driver         = {
                .name   = "rtc-nct3018y",
                .of_match_table = nct3018y_of_match,
        },
        .probe          = nct3018y_probe,
        .id_table       = nct3018y_id,
};

module_i2c_driver(nct3018y_driver);

MODULE_AUTHOR("Medad CChien <ctcchien@nuvoton.com>");
MODULE_AUTHOR("Mia Lin <mimi05633@gmail.com>");
MODULE_DESCRIPTION("Nuvoton NCT3018Y RTC driver");
MODULE_LICENSE("GPL");