/*
 * Haoyu HYM8563 RTC driver
 *
 * Copyright (C) 2013 MundoReader S.L.
 * Author: Heiko Stuebner <heiko@sntech.de>
 *
 * based on rtc-HYM8563
 * Copyright (C) 2010 ROCKCHIP, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#define HYM8563_CTL1            0x00
#define HYM8563_CTL1_TEST       BIT(7)
#define HYM8563_CTL1_STOP       BIT(5)
#define HYM8563_CTL1_TESTC      BIT(3)

#define HYM8563_CTL2            0x01
#define HYM8563_CTL2_TI_TP      BIT(4)
#define HYM8563_CTL2_AF         BIT(3)
#define HYM8563_CTL2_TF         BIT(2)
#define HYM8563_CTL2_AIE        BIT(1)
#define HYM8563_CTL2_TIE        BIT(0)

#define HYM8563_SEC             0x02
#define HYM8563_SEC_VL          BIT(7)
#define HYM8563_SEC_MASK        0x7f

#define HYM8563_MIN             0x03
#define HYM8563_MIN_MASK        0x7f

#define HYM8563_HOUR            0x04
#define HYM8563_HOUR_MASK       0x3f

#define HYM8563_DAY             0x05
#define HYM8563_DAY_MASK        0x3f

#define HYM8563_WEEKDAY         0x06
#define HYM8563_WEEKDAY_MASK    0x07

#define HYM8563_MONTH           0x07
#define HYM8563_MONTH_CENTURY   BIT(7)
#define HYM8563_MONTH_MASK      0x1f

#define HYM8563_YEAR            0x08

#define HYM8563_ALM_MIN         0x09
#define HYM8563_ALM_HOUR        0x0a
#define HYM8563_ALM_DAY         0x0b
#define HYM8563_ALM_WEEK        0x0c

/* Each alarm check can be disabled by setting this bit in the register */
#define HYM8563_ALM_BIT_DISABLE BIT(7)

#define HYM8563_CLKOUT          0x0d
#define HYM8563_CLKOUT_ENABLE   BIT(7)
#define HYM8563_CLKOUT_32768    0
#define HYM8563_CLKOUT_1024     1
#define HYM8563_CLKOUT_32       2
#define HYM8563_CLKOUT_1        3
#define HYM8563_CLKOUT_MASK     3

#define HYM8563_TMR_CTL         0x0e
#define HYM8563_TMR_CTL_ENABLE  BIT(7)
#define HYM8563_TMR_CTL_4096    0
#define HYM8563_TMR_CTL_64      1
#define HYM8563_TMR_CTL_1       2
#define HYM8563_TMR_CTL_1_60    3
#define HYM8563_TMR_CTL_MASK    3

#define HYM8563_TMR_CNT         0x0f

struct hym8563 {
        struct i2c_client       *client;
        struct rtc_device       *rtc;
        bool                    valid;
#ifdef CONFIG_COMMON_CLK
        struct clk_hw           clkout_hw;
#endif
};

/*
 * RTC handling
 */

static int hym8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct hym8563 *hym8563 = i2c_get_clientdata(client);
        u8 buf[7];
        int ret;

        if (!hym8563->valid) {
                dev_warn(&client->dev, "no valid clock/calendar values available\n");
                return -EPERM;
        }

        ret = i2c_smbus_read_i2c_block_data(client, HYM8563_SEC, 7, buf);

        tm->tm_sec = bcd2bin(buf[0] & HYM8563_SEC_MASK);
        tm->tm_min = bcd2bin(buf[1] & HYM8563_MIN_MASK);
        tm->tm_hour = bcd2bin(buf[2] & HYM8563_HOUR_MASK);
        tm->tm_mday = bcd2bin(buf[3] & HYM8563_DAY_MASK);
        tm->tm_wday = bcd2bin(buf[4] & HYM8563_WEEKDAY_MASK); /* 0 = Sun */
        tm->tm_mon = bcd2bin(buf[5] & HYM8563_MONTH_MASK) - 1; /* 0 = Jan */
        tm->tm_year = bcd2bin(buf[6]) + 100;

        return 0;
}

static int hym8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct hym8563 *hym8563 = i2c_get_clientdata(client);
        u8 buf[7];
        int ret;

        /* Years >= 2100 are to far in the future, 19XX is to early */
        if (tm->tm_year < 100 || tm->tm_year >= 200)
                return -EINVAL;

        buf[0] = bin2bcd(tm->tm_sec);
        buf[1] = bin2bcd(tm->tm_min);
        buf[2] = bin2bcd(tm->tm_hour);
        buf[3] = bin2bcd(tm->tm_mday);
        buf[4] = bin2bcd(tm->tm_wday);
        buf[5] = bin2bcd(tm->tm_mon + 1);

        /*
         * While the HYM8563 has a century flag in the month register,
         * it does not seem to carry it over a subsequent write/read.
         * So we'll limit ourself to 100 years, starting at 2000 for now.
         */
        buf[6] = tm->tm_year - 100;

        /*
         * CTL1 only contains TEST-mode bits apart from stop,
         * so no need to read the value first
         */
        ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1,
                                                HYM8563_CTL1_STOP);
        if (ret < 0)
                return ret;

        ret = i2c_smbus_write_i2c_block_data(client, HYM8563_SEC, 7, buf);
        if (ret < 0)
                return ret;

        ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1, 0);
        if (ret < 0)
                return ret;

        hym8563->valid = true;

        return 0;
}

static int hym8563_rtc_alarm_irq_enable(struct device *dev,
                                        unsigned int enabled)
{
        struct i2c_client *client = to_i2c_client(dev);
        int data;

        data = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
        if (data < 0)
                return data;

        if (enabled)
                data |= HYM8563_CTL2_AIE;
        else
                data &= ~HYM8563_CTL2_AIE;

        return i2c_smbus_write_byte_data(client, HYM8563_CTL2, data);
};

static int hym8563_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rtc_time *alm_tm = &alm->time;
        u8 buf[4];
        int ret;

        ret = i2c_smbus_read_i2c_block_data(client, HYM8563_ALM_MIN, 4, buf);
        if (ret < 0)
                return ret;

        /* The alarm only has a minute accuracy */
        alm_tm->tm_sec = -1;

        alm_tm->tm_min = (buf[0] & HYM8563_ALM_BIT_DISABLE) ?
                                        -1 :
                                        bcd2bin(buf[0] & HYM8563_MIN_MASK);
        alm_tm->tm_hour = (buf[1] & HYM8563_ALM_BIT_DISABLE) ?
                                        -1 :
                                        bcd2bin(buf[1] & HYM8563_HOUR_MASK);
        alm_tm->tm_mday = (buf[2] & HYM8563_ALM_BIT_DISABLE) ?
                                        -1 :
                                        bcd2bin(buf[2] & HYM8563_DAY_MASK);
        alm_tm->tm_wday = (buf[3] & HYM8563_ALM_BIT_DISABLE) ?
                                        -1 :
                                        bcd2bin(buf[3] & HYM8563_WEEKDAY_MASK);

        alm_tm->tm_mon = -1;
        alm_tm->tm_year = -1;

        ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
        if (ret < 0)
                return ret;

        if (ret & HYM8563_CTL2_AIE)
                alm->enabled = 1;

        return 0;
}

static int hym8563_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rtc_time *alm_tm = &alm->time;
        u8 buf[4];
        int ret;

        /*
         * The alarm has no seconds so deal with it
         */
        if (alm_tm->tm_sec) {
                alm_tm->tm_sec = 0;
                alm_tm->tm_min++;
                if (alm_tm->tm_min >= 60) {
                        alm_tm->tm_min = 0;
                        alm_tm->tm_hour++;
                        if (alm_tm->tm_hour >= 24) {
                                alm_tm->tm_hour = 0;
                                alm_tm->tm_mday++;
                                if (alm_tm->tm_mday > 31)
                                        alm_tm->tm_mday = 0;
                        }
                }
        }

        ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
        if (ret < 0)
                return ret;

        ret &= ~HYM8563_CTL2_AIE;

        ret = i2c_smbus_write_byte_data(client, HYM8563_CTL2, ret);
        if (ret < 0)
                return ret;

        buf[0] = (alm_tm->tm_min < 60 && alm_tm->tm_min >= 0) ?
                        bin2bcd(alm_tm->tm_min) : HYM8563_ALM_BIT_DISABLE;

        buf[1] = (alm_tm->tm_hour < 24 && alm_tm->tm_hour >= 0) ?
                        bin2bcd(alm_tm->tm_hour) : HYM8563_ALM_BIT_DISABLE;

        buf[2] = (alm_tm->tm_mday <= 31 && alm_tm->tm_mday >= 1) ?
                        bin2bcd(alm_tm->tm_mday) : HYM8563_ALM_BIT_DISABLE;

        buf[3] = (alm_tm->tm_wday < 7 && alm_tm->tm_wday >= 0) ?
                        bin2bcd(alm_tm->tm_wday) : HYM8563_ALM_BIT_DISABLE;

        ret = i2c_smbus_write_i2c_block_data(client, HYM8563_ALM_MIN, 4, buf);
        if (ret < 0)
                return ret;

        return hym8563_rtc_alarm_irq_enable(dev, alm->enabled);
}

static const struct rtc_class_ops hym8563_rtc_ops = {
        .read_time              = hym8563_rtc_read_time,
        .set_time               = hym8563_rtc_set_time,
        .alarm_irq_enable       = hym8563_rtc_alarm_irq_enable,
        .read_alarm             = hym8563_rtc_read_alarm,
        .set_alarm              = hym8563_rtc_set_alarm,
};

/*
 * Handling of the clkout
 */

#ifdef CONFIG_COMMON_CLK
#define clkout_hw_to_hym8563(_hw) container_of(_hw, struct hym8563, clkout_hw)

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

static unsigned long hym8563_clkout_recalc_rate(struct clk_hw *hw,
                                                unsigned long parent_rate)
{
        struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
        struct i2c_client *client = hym8563->client;
        int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);

        if (ret < 0)
                return 0;

        ret &= HYM8563_CLKOUT_MASK;
        return clkout_rates[ret];
}

static long hym8563_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 hym8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
                                   unsigned long parent_rate)
{
        struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
        struct i2c_client *client = hym8563->client;
        int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);
        int i;

        if (ret < 0)
                return ret;

        for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
                if (clkout_rates[i] == rate) {
                        ret &= ~HYM8563_CLKOUT_MASK;
                        ret |= i;
                        return i2c_smbus_write_byte_data(client,
                                                         HYM8563_CLKOUT, ret);
                }

        return -EINVAL;
}

static int hym8563_clkout_control(struct clk_hw *hw, bool enable)
{
        struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
        struct i2c_client *client = hym8563->client;
        int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);

        if (ret < 0)
                return ret;

        if (enable)
                ret |= HYM8563_CLKOUT_ENABLE;
        else
                ret &= ~HYM8563_CLKOUT_ENABLE;

        return i2c_smbus_write_byte_data(client, HYM8563_CLKOUT, ret);
}

static int hym8563_clkout_prepare(struct clk_hw *hw)
{
        return hym8563_clkout_control(hw, 1);
}

static void hym8563_clkout_unprepare(struct clk_hw *hw)
{
        hym8563_clkout_control(hw, 0);
}

static int hym8563_clkout_is_prepared(struct clk_hw *hw)
{
        struct hym8563 *hym8563 = clkout_hw_to_hym8563(hw);
        struct i2c_client *client = hym8563->client;
        int ret = i2c_smbus_read_byte_data(client, HYM8563_CLKOUT);

        if (ret < 0)
                return ret;

        return !!(ret & HYM8563_CLKOUT_ENABLE);
}

static const struct clk_ops hym8563_clkout_ops = {
        .prepare = hym8563_clkout_prepare,
        .unprepare = hym8563_clkout_unprepare,
        .is_prepared = hym8563_clkout_is_prepared,
        .recalc_rate = hym8563_clkout_recalc_rate,
        .round_rate = hym8563_clkout_round_rate,
        .set_rate = hym8563_clkout_set_rate,
};

static struct clk *hym8563_clkout_register_clk(struct hym8563 *hym8563)
{
        struct i2c_client *client = hym8563->client;
        struct device_node *node = client->dev.of_node;
        struct clk *clk;
        struct clk_init_data init;
        int ret;

        ret = i2c_smbus_write_byte_data(client, HYM8563_CLKOUT,
                                                0);
        if (ret < 0)
                return ERR_PTR(ret);

        init.name = "hym8563-clkout";
        init.ops = &hym8563_clkout_ops;
        init.flags = CLK_IS_ROOT;
        init.parent_names = NULL;
        init.num_parents = 0;
        hym8563->clkout_hw.init = &init;

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

        /* register the clock */
        clk = clk_register(&client->dev, &hym8563->clkout_hw);

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

        return clk;
}
#endif

/*
 * The alarm interrupt is implemented as a level-low interrupt in the
 * hym8563, while the timer interrupt uses a falling edge.
 * We don't use the timer at all, so the interrupt is requested to
 * use the level-low trigger.
 */
static irqreturn_t hym8563_irq(int irq, void *dev_id)
{
        struct hym8563 *hym8563 = (struct hym8563 *)dev_id;
        struct i2c_client *client = hym8563->client;
        struct mutex *lock = &hym8563->rtc->ops_lock;
        int data, ret;

        mutex_lock(lock);

        /* Clear the alarm flag */

        data = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
        if (data < 0) {
                dev_err(&client->dev, "%s: error reading i2c data %d\n",
                        __func__, data);
                goto out;
        }

        data &= ~HYM8563_CTL2_AF;

        ret = i2c_smbus_write_byte_data(client, HYM8563_CTL2, data);
        if (ret < 0) {
                dev_err(&client->dev, "%s: error writing i2c data %d\n",
                        __func__, ret);
        }

out:
        mutex_unlock(lock);
        return IRQ_HANDLED;
}

static int hym8563_init_device(struct i2c_client *client)
{
        int ret;

        /* Clear stop flag if present */
        ret = i2c_smbus_write_byte_data(client, HYM8563_CTL1, 0);
        if (ret < 0)
                return ret;

        ret = i2c_smbus_read_byte_data(client, HYM8563_CTL2);
        if (ret < 0)
                return ret;

        /* Disable alarm and timer interrupts */
        ret &= ~HYM8563_CTL2_AIE;
        ret &= ~HYM8563_CTL2_TIE;

        /* Clear any pending alarm and timer flags */
        if (ret & HYM8563_CTL2_AF)
                ret &= ~HYM8563_CTL2_AF;

        if (ret & HYM8563_CTL2_TF)
                ret &= ~HYM8563_CTL2_TF;

        ret &= ~HYM8563_CTL2_TI_TP;

        return i2c_smbus_write_byte_data(client, HYM8563_CTL2, ret);
}

#ifdef CONFIG_PM_SLEEP
static int hym8563_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        int ret;

        if (device_may_wakeup(dev)) {
                ret = enable_irq_wake(client->irq);
                if (ret) {
                        dev_err(dev, "enable_irq_wake failed, %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

static int hym8563_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

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

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(hym8563_pm_ops, hym8563_suspend, hym8563_resume);

static int hym8563_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
{
        struct hym8563 *hym8563;
        int ret;

        hym8563 = devm_kzalloc(&client->dev, sizeof(*hym8563), GFP_KERNEL);
        if (!hym8563)
                return -ENOMEM;

        hym8563->client = client;
        i2c_set_clientdata(client, hym8563);

        device_set_wakeup_capable(&client->dev, true);

        ret = hym8563_init_device(client);
        if (ret) {
                dev_err(&client->dev, "could not init device, %d\n", ret);
                return ret;
        }

        ret = devm_request_threaded_irq(&client->dev, client->irq,
                                        NULL, hym8563_irq,
                                        IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                                        client->name, hym8563);
        if (ret < 0) {
                dev_err(&client->dev, "irq %d request failed, %d\n",
                        client->irq, ret);
                return ret;
        }

        /* check state of calendar information */
        ret = i2c_smbus_read_byte_data(client, HYM8563_SEC);
        if (ret < 0)
                return ret;

        hym8563->valid = !(ret & HYM8563_SEC_VL);
        dev_dbg(&client->dev, "rtc information is %s\n",
                hym8563->valid ? "valid" : "invalid");

        hym8563->rtc = devm_rtc_device_register(&client->dev, client->name,
                                                &hym8563_rtc_ops, THIS_MODULE);
        if (IS_ERR(hym8563->rtc))
                return PTR_ERR(hym8563->rtc);

        /* the hym8563 alarm only supports a minute accuracy */
        hym8563->rtc->uie_unsupported = 1;

#ifdef CONFIG_COMMON_CLK
        hym8563_clkout_register_clk(hym8563);
#endif

        return 0;
}

static const struct i2c_device_id hym8563_id[] = {
        { "hym8563", 0 },
        {},
};
MODULE_DEVICE_TABLE(i2c, hym8563_id);

static const struct of_device_id hym8563_dt_idtable[] = {
        { .compatible = "haoyu,hym8563" },
        {},
};
MODULE_DEVICE_TABLE(of, hym8563_dt_idtable);

static struct i2c_driver hym8563_driver = {
        .driver         = {
                .name   = "rtc-hym8563",
                .owner  = THIS_MODULE,
                .pm     = &hym8563_pm_ops,
                .of_match_table = hym8563_dt_idtable,
        },
        .probe          = hym8563_probe,
        .id_table       = hym8563_id,
};

module_i2c_driver(hym8563_driver);

MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
MODULE_DESCRIPTION("HYM8563 RTC driver");
MODULE_LICENSE("GPL");