/*
 * An I2C driver for the Philips PCF8563 RTC
 * Copyright 2005-06 Tower Technologies
 *
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 * Maintainers: http://www.nslu2-linux.org/
 *
 * based on the other drivers in this same directory.
 *
 * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

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

#define PCF8563_REG_ST1         0x00 /* status */
#define PCF8563_REG_ST2         0x01
#define PCF8563_BIT_AIE         (1 << 1)
#define PCF8563_BIT_AF          (1 << 3)
#define PCF8563_BITS_ST2_N      (7 << 5)

#define PCF8563_REG_SC          0x02 /* datetime */
#define PCF8563_REG_MN          0x03
#define PCF8563_REG_HR          0x04
#define PCF8563_REG_DM          0x05
#define PCF8563_REG_DW          0x06
#define PCF8563_REG_MO          0x07
#define PCF8563_REG_YR          0x08

#define PCF8563_REG_AMN         0x09 /* alarm */

#define PCF8563_REG_CLKO                0x0D /* clock out */
#define PCF8563_REG_CLKO_FE             0x80 /* clock out enabled */
#define PCF8563_REG_CLKO_F_MASK         0x03 /* frequenc mask */
#define PCF8563_REG_CLKO_F_32768HZ      0x00
#define PCF8563_REG_CLKO_F_1024HZ       0x01
#define PCF8563_REG_CLKO_F_32HZ         0x02
#define PCF8563_REG_CLKO_F_1HZ          0x03

#define PCF8563_REG_TMRC        0x0E /* timer control */
#define PCF8563_TMRC_ENABLE     BIT(7)
#define PCF8563_TMRC_4096       0
#define PCF8563_TMRC_64         1
#define PCF8563_TMRC_1          2
#define PCF8563_TMRC_1_60       3
#define PCF8563_TMRC_MASK       3

#define PCF8563_REG_TMR         0x0F /* timer */

#define PCF8563_SC_LV           0x80 /* low voltage */
#define PCF8563_MO_C            0x80 /* century */

static struct i2c_driver pcf8563_driver;

struct pcf8563 {
        struct rtc_device *rtc;
        /*
         * The meaning of MO_C bit varies by the chip type.
         * From PCF8563 datasheet: this bit is toggled when the years
         * register overflows from 99 to 00
         *   0 indicates the century is 20xx
         *   1 indicates the century is 19xx
         * From RTC8564 datasheet: this bit indicates change of
         * century. When the year digit data overflows from 99 to 00,
         * this bit is set. By presetting it to 0 while still in the
         * 20th century, it will be set in year 2000, ...
         * There seems no reliable way to know how the system use this
         * bit.  So let's do it heuristically, assuming we are live in
         * 1970...2069.
         */
        int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
        int voltage_low; /* incicates if a low_voltage was detected */

        struct i2c_client *client;
#ifdef CONFIG_COMMON_CLK
        struct clk_hw           clkout_hw;
#endif
};

static int pcf8563_read_block_data(struct i2c_client *client, unsigned char reg,
                                   unsigned char length, unsigned char *buf)
{
        struct i2c_msg msgs[] = {
                {/* setup read ptr */
                        .addr = client->addr,
                        .len = 1,
                        .buf = &reg,
                },
                {
                        .addr = client->addr,
                        .flags = I2C_M_RD,
                        .len = length,
                        .buf = buf
                },
        };

        if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return -EIO;
        }

        return 0;
}

static int pcf8563_write_block_data(struct i2c_client *client,
                                   unsigned char reg, unsigned char length,
                                   unsigned char *buf)
{
        int i, err;

        for (i = 0; i < length; i++) {
                unsigned char data[2] = { reg + i, buf[i] };

                err = i2c_master_send(client, data, sizeof(data));
                if (err != sizeof(data)) {
                        dev_err(&client->dev,
                                "%s: err=%d addr=%02x, data=%02x\n",
                                __func__, err, data[0], data[1]);
                        return -EIO;
                }
        }

        return 0;
}

static int pcf8563_set_alarm_mode(struct i2c_client *client, bool on)
{
        unsigned char buf;
        int err;

        err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
        if (err < 0)
                return err;

        if (on)
                buf |= PCF8563_BIT_AIE;
        else
                buf &= ~PCF8563_BIT_AIE;

        buf &= ~(PCF8563_BIT_AF | PCF8563_BITS_ST2_N);

        err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
        if (err < 0) {
                dev_err(&client->dev, "%s: write error\n", __func__);
                return -EIO;
        }

        return 0;
}

static int pcf8563_get_alarm_mode(struct i2c_client *client, unsigned char *en,
                                  unsigned char *pen)
{
        unsigned char buf;
        int err;

        err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
        if (err)
                return err;

        if (en)
                *en = !!(buf & PCF8563_BIT_AIE);
        if (pen)
                *pen = !!(buf & PCF8563_BIT_AF);

        return 0;
}

static irqreturn_t pcf8563_irq(int irq, void *dev_id)
{
        struct pcf8563 *pcf8563 = i2c_get_clientdata(dev_id);
        int err;
        char pending;

        err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
        if (err)
                return IRQ_NONE;

        if (pending) {
                rtc_update_irq(pcf8563->rtc, 1, RTC_IRQF | RTC_AF);
                pcf8563_set_alarm_mode(pcf8563->client, 1);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/*
 * In the routines that deal directly with the pcf8563 hardware, we use
 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 */
static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
        unsigned char buf[9];
        int err;

        err = pcf8563_read_block_data(client, PCF8563_REG_ST1, 9, buf);
        if (err)
                return err;

        if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
                pcf8563->voltage_low = 1;
                dev_err(&client->dev,
                        "low voltage detected, date/time is not reliable.\n");
                return -EINVAL;
        }

        dev_dbg(&client->dev,
                "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
                "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
                __func__,
                buf[0], buf[1], buf[2], buf[3],
                buf[4], buf[5], buf[6], buf[7],
                buf[8]);


        tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
        tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
        tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
        tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
        tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
        tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
        tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
        if (tm->tm_year < 70)
                tm->tm_year += 100;     /* assume we are in 1970...2069 */
        /* detect the polarity heuristically. see note above. */
        pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
                (tm->tm_year >= 100) : (tm->tm_year < 100);

        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
                "mday=%d, mon=%d, year=%d, wday=%d\n",
                __func__,
                tm->tm_sec, tm->tm_min, tm->tm_hour,
                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

        return 0;
}

static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
        unsigned char buf[9];

        dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
                "mday=%d, mon=%d, year=%d, wday=%d\n",
                __func__,
                tm->tm_sec, tm->tm_min, tm->tm_hour,
                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

        /* hours, minutes and seconds */
        buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
        buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
        buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);

        buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);

        /* month, 1 - 12 */
        buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);

        /* year and century */
        buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
        if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
                buf[PCF8563_REG_MO] |= PCF8563_MO_C;

        buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;

        return pcf8563_write_block_data(client, PCF8563_REG_SC,
                                9 - PCF8563_REG_SC, buf + PCF8563_REG_SC);
}

#ifdef CONFIG_RTC_INTF_DEV
static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
        struct rtc_time tm;

        switch (cmd) {
        case RTC_VL_READ:
                if (pcf8563->voltage_low)
                        dev_info(dev, "low voltage detected, date/time is not reliable.\n");

                if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
                                        sizeof(int)))
                        return -EFAULT;
                return 0;
        case RTC_VL_CLR:
                /*
                 * Clear the VL bit in the seconds register in case
                 * the time has not been set already (which would
                 * have cleared it). This does not really matter
                 * because of the cached voltage_low value but do it
                 * anyway for consistency.
                 */
                if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
                        pcf8563_set_datetime(to_i2c_client(dev), &tm);

                /* Clear the cached value. */
                pcf8563->voltage_low = 0;

                return 0;
        default:
                return -ENOIOCTLCMD;
        }
}
#else
#define pcf8563_rtc_ioctl NULL
#endif

static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        return pcf8563_get_datetime(to_i2c_client(dev), tm);
}

static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        return pcf8563_set_datetime(to_i2c_client(dev), tm);
}

static int pcf8563_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[4];
        int err;

        err = pcf8563_read_block_data(client, PCF8563_REG_AMN, 4, buf);
        if (err)
                return err;

        dev_dbg(&client->dev,
                "%s: raw data is min=%02x, hr=%02x, mday=%02x, wday=%02x\n",
                __func__, buf[0], buf[1], buf[2], buf[3]);

        tm->time.tm_sec = 0;
        tm->time.tm_min = bcd2bin(buf[0] & 0x7F);
        tm->time.tm_hour = bcd2bin(buf[1] & 0x3F);
        tm->time.tm_mday = bcd2bin(buf[2] & 0x3F);
        tm->time.tm_wday = bcd2bin(buf[3] & 0x7);

        err = pcf8563_get_alarm_mode(client, &tm->enabled, &tm->pending);
        if (err < 0)
                return err;

        dev_dbg(&client->dev, "%s: tm is mins=%d, hours=%d, mday=%d, wday=%d,"
                " enabled=%d, pending=%d\n", __func__, tm->time.tm_min,
                tm->time.tm_hour, tm->time.tm_mday, tm->time.tm_wday,
                tm->enabled, tm->pending);

        return 0;
}

static int pcf8563_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        unsigned char buf[4];
        int err;

        /* The alarm has no seconds, round up to nearest minute */
        if (tm->time.tm_sec) {
                time64_t alarm_time = rtc_tm_to_time64(&tm->time);

                alarm_time += 60 - tm->time.tm_sec;
                rtc_time64_to_tm(alarm_time, &tm->time);
        }

        dev_dbg(dev, "%s, min=%d hour=%d wday=%d mday=%d "
                "enabled=%d pending=%d\n", __func__,
                tm->time.tm_min, tm->time.tm_hour, tm->time.tm_wday,
                tm->time.tm_mday, tm->enabled, tm->pending);

        buf[0] = bin2bcd(tm->time.tm_min);
        buf[1] = bin2bcd(tm->time.tm_hour);
        buf[2] = bin2bcd(tm->time.tm_mday);
        buf[3] = tm->time.tm_wday & 0x07;

        err = pcf8563_write_block_data(client, PCF8563_REG_AMN, 4, buf);
        if (err)
                return err;

        return pcf8563_set_alarm_mode(client, !!tm->enabled);
}

static int pcf8563_irq_enable(struct device *dev, unsigned int enabled)
{
        dev_dbg(dev, "%s: en=%d\n", __func__, enabled);
        return pcf8563_set_alarm_mode(to_i2c_client(dev), !!enabled);
}

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

#define clkout_hw_to_pcf8563(_hw) container_of(_hw, struct pcf8563, clkout_hw)

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

static unsigned long pcf8563_clkout_recalc_rate(struct clk_hw *hw,
                                                unsigned long parent_rate)
{
        struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
        struct i2c_client *client = pcf8563->client;
        unsigned char buf;
        int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

        if (ret < 0)
                return 0;

        buf &= PCF8563_REG_CLKO_F_MASK;
        return clkout_rates[buf];
}

static long pcf8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
                                      unsigned long *prate)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
                if (clkout_rates[i] <= rate)
                        return clkout_rates[i];

        return 0;
}

static int pcf8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
                                   unsigned long parent_rate)
{
        struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
        struct i2c_client *client = pcf8563->client;
        unsigned char buf;
        int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
        int i;

        if (ret < 0)
                return ret;

        for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
                if (clkout_rates[i] == rate) {
                        buf &= ~PCF8563_REG_CLKO_F_MASK;
                        buf |= i;
                        ret = pcf8563_write_block_data(client,
                                                       PCF8563_REG_CLKO, 1,
                                                       &buf);
                        return ret;
                }

        return -EINVAL;
}

static int pcf8563_clkout_control(struct clk_hw *hw, bool enable)
{
        struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
        struct i2c_client *client = pcf8563->client;
        unsigned char buf;
        int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

        if (ret < 0)
                return ret;

        if (enable)
                buf |= PCF8563_REG_CLKO_FE;
        else
                buf &= ~PCF8563_REG_CLKO_FE;

        ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
        return ret;
}

static int pcf8563_clkout_prepare(struct clk_hw *hw)
{
        return pcf8563_clkout_control(hw, 1);
}

static void pcf8563_clkout_unprepare(struct clk_hw *hw)
{
        pcf8563_clkout_control(hw, 0);
}

static int pcf8563_clkout_is_prepared(struct clk_hw *hw)
{
        struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
        struct i2c_client *client = pcf8563->client;
        unsigned char buf;
        int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

        if (ret < 0)
                return ret;

        return !!(buf & PCF8563_REG_CLKO_FE);
}

static const struct clk_ops pcf8563_clkout_ops = {
        .prepare = pcf8563_clkout_prepare,
        .unprepare = pcf8563_clkout_unprepare,
        .is_prepared = pcf8563_clkout_is_prepared,
        .recalc_rate = pcf8563_clkout_recalc_rate,
        .round_rate = pcf8563_clkout_round_rate,
        .set_rate = pcf8563_clkout_set_rate,
};

static struct clk *pcf8563_clkout_register_clk(struct pcf8563 *pcf8563)
{
        struct i2c_client *client = pcf8563->client;
        struct device_node *node = client->dev.of_node;
        struct clk *clk;
        struct clk_init_data init;
        int ret;
        unsigned char buf;

        /* disable the clkout output */
        buf = 0;
        ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
        if (ret < 0)
                return ERR_PTR(ret);

        init.name = "pcf8563-clkout";
        init.ops = &pcf8563_clkout_ops;
        init.flags = 0;
        init.parent_names = NULL;
        init.num_parents = 0;
        pcf8563->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, &pcf8563->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 pcf8563_rtc_ops = {
        .ioctl          = pcf8563_rtc_ioctl,
        .read_time      = pcf8563_rtc_read_time,
        .set_time       = pcf8563_rtc_set_time,
        .read_alarm     = pcf8563_rtc_read_alarm,
        .set_alarm      = pcf8563_rtc_set_alarm,
        .alarm_irq_enable = pcf8563_irq_enable,
};

static int pcf8563_probe(struct i2c_client *client,
                                const struct i2c_device_id *id)
{
        struct pcf8563 *pcf8563;
        int err;
        unsigned char buf;
        unsigned char alm_pending;

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

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

        pcf8563 = devm_kzalloc(&client->dev, sizeof(struct pcf8563),
                                GFP_KERNEL);
        if (!pcf8563)
                return -ENOMEM;

        i2c_set_clientdata(client, pcf8563);
        pcf8563->client = client;
        device_set_wakeup_capable(&client->dev, 1);

        /* Set timer to lowest frequency to save power (ref Haoyu datasheet) */
        buf = PCF8563_TMRC_1_60;
        err = pcf8563_write_block_data(client, PCF8563_REG_TMRC, 1, &buf);
        if (err < 0) {
                dev_err(&client->dev, "%s: write error\n", __func__);
                return err;
        }

        err = pcf8563_get_alarm_mode(client, NULL, &alm_pending);
        if (err) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return err;
        }
        if (alm_pending)
                pcf8563_set_alarm_mode(client, 0);

        pcf8563->rtc = devm_rtc_device_register(&client->dev,
                                pcf8563_driver.driver.name,
                                &pcf8563_rtc_ops, THIS_MODULE);

        if (IS_ERR(pcf8563->rtc))
                return PTR_ERR(pcf8563->rtc);

        if (client->irq > 0) {
                err = devm_request_threaded_irq(&client->dev, client->irq,
                                NULL, pcf8563_irq,
                                IRQF_SHARED|IRQF_ONESHOT|IRQF_TRIGGER_FALLING,
                                pcf8563_driver.driver.name, client);
                if (err) {
                        dev_err(&client->dev, "unable to request IRQ %d\n",
                                                                client->irq);
                        return err;
                }

        }

#ifdef CONFIG_COMMON_CLK
        /* register clk in common clk framework */
        pcf8563_clkout_register_clk(pcf8563);
#endif

        /* the pcf8563 alarm only supports a minute accuracy */
        pcf8563->rtc->uie_unsupported = 1;

        return 0;
}

static const struct i2c_device_id pcf8563_id[] = {
        { "pcf8563", 0 },
        { "rtc8564", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, pcf8563_id);

#ifdef CONFIG_OF
static const struct of_device_id pcf8563_of_match[] = {
        { .compatible = "nxp,pcf8563" },
        {}
};
MODULE_DEVICE_TABLE(of, pcf8563_of_match);
#endif

static struct i2c_driver pcf8563_driver = {
        .driver         = {
                .name   = "rtc-pcf8563",
                .of_match_table = of_match_ptr(pcf8563_of_match),
        },
        .probe          = pcf8563_probe,
        .id_table       = pcf8563_id,
};

module_i2c_driver(pcf8563_driver);

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
MODULE_LICENSE("GPL");