/* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * 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/of.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

/* RTC Register offsets from RTC CTRL REG */
#define PM8XXX_ALARM_CTRL_OFFSET        0x01
#define PM8XXX_RTC_WRITE_OFFSET         0x02
#define PM8XXX_RTC_READ_OFFSET          0x06
#define PM8XXX_ALARM_RW_OFFSET          0x0A

/* RTC_CTRL register bit fields */
#define PM8xxx_RTC_ENABLE               BIT(7)
#define PM8xxx_RTC_ALARM_CLEAR          BIT(0)

#define NUM_8_BIT_RTC_REGS              0x4

/**
 * struct pm8xxx_rtc_regs - describe RTC registers per PMIC versions
 * @ctrl: base address of control register
 * @write: base address of write register
 * @read: base address of read register
 * @alarm_ctrl: base address of alarm control register
 * @alarm_ctrl2: base address of alarm control2 register
 * @alarm_rw: base address of alarm read-write register
 * @alarm_en: alarm enable mask
 */
struct pm8xxx_rtc_regs {
        unsigned int ctrl;
        unsigned int write;
        unsigned int read;
        unsigned int alarm_ctrl;
        unsigned int alarm_ctrl2;
        unsigned int alarm_rw;
        unsigned int alarm_en;
};

/**
 * struct pm8xxx_rtc -  rtc driver internal structure
 * @rtc:                rtc device for this driver.
 * @regmap:             regmap used to access RTC registers
 * @allow_set_time:     indicates whether writing to the RTC is allowed
 * @rtc_alarm_irq:      rtc alarm irq number.
 * @ctrl_reg:           rtc control register.
 * @rtc_dev:            device structure.
 * @ctrl_reg_lock:      spinlock protecting access to ctrl_reg.
 */
struct pm8xxx_rtc {
        struct rtc_device *rtc;
        struct regmap *regmap;
        bool allow_set_time;
        int rtc_alarm_irq;
        const struct pm8xxx_rtc_regs *regs;
        struct device *rtc_dev;
        spinlock_t ctrl_reg_lock;
};

/*
 * Steps to write the RTC registers.
 * 1. Disable alarm if enabled.
 * 2. Disable rtc if enabled.
 * 3. Write 0x00 to LSB.
 * 4. Write Byte[1], Byte[2], Byte[3] then Byte[0].
 * 5. Enable rtc if disabled in step 2.
 * 6. Enable alarm if disabled in step 1.
 */
static int pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        int rc, i;
        unsigned long secs, irq_flags;
        u8 value[NUM_8_BIT_RTC_REGS], alarm_enabled = 0, rtc_disabled = 0;
        unsigned int ctrl_reg, rtc_ctrl_reg;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;

        if (!rtc_dd->allow_set_time)
                return -EACCES;

        rtc_tm_to_time(tm, &secs);

        dev_dbg(dev, "Seconds value to be written to RTC = %lu\n", secs);

        for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
                value[i] = secs & 0xFF;
                secs >>= 8;
        }

        spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);

        rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
        if (rc)
                goto rtc_rw_fail;

        if (ctrl_reg & regs->alarm_en) {
                alarm_enabled = 1;
                ctrl_reg &= ~regs->alarm_en;
                rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
                if (rc) {
                        dev_err(dev, "Write to RTC Alarm control register failed\n");
                        goto rtc_rw_fail;
                }
        }

        /* Disable RTC H/w before writing on RTC register */
        rc = regmap_read(rtc_dd->regmap, regs->ctrl, &rtc_ctrl_reg);
        if (rc)
                goto rtc_rw_fail;

        if (rtc_ctrl_reg & PM8xxx_RTC_ENABLE) {
                rtc_disabled = 1;
                rtc_ctrl_reg &= ~PM8xxx_RTC_ENABLE;
                rc = regmap_write(rtc_dd->regmap, regs->ctrl, rtc_ctrl_reg);
                if (rc) {
                        dev_err(dev, "Write to RTC control register failed\n");
                        goto rtc_rw_fail;
                }
        }

        /* Write 0 to Byte[0] */
        rc = regmap_write(rtc_dd->regmap, regs->write, 0);
        if (rc) {
                dev_err(dev, "Write to RTC write data register failed\n");
                goto rtc_rw_fail;
        }

        /* Write Byte[1], Byte[2], Byte[3] */
        rc = regmap_bulk_write(rtc_dd->regmap, regs->write + 1,
                               &value[1], sizeof(value) - 1);
        if (rc) {
                dev_err(dev, "Write to RTC write data register failed\n");
                goto rtc_rw_fail;
        }

        /* Write Byte[0] */
        rc = regmap_write(rtc_dd->regmap, regs->write, value[0]);
        if (rc) {
                dev_err(dev, "Write to RTC write data register failed\n");
                goto rtc_rw_fail;
        }

        /* Enable RTC H/w after writing on RTC register */
        if (rtc_disabled) {
                rtc_ctrl_reg |= PM8xxx_RTC_ENABLE;
                rc = regmap_write(rtc_dd->regmap, regs->ctrl, rtc_ctrl_reg);
                if (rc) {
                        dev_err(dev, "Write to RTC control register failed\n");
                        goto rtc_rw_fail;
                }
        }

        if (alarm_enabled) {
                ctrl_reg |= regs->alarm_en;
                rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
                if (rc) {
                        dev_err(dev, "Write to RTC Alarm control register failed\n");
                        goto rtc_rw_fail;
                }
        }

rtc_rw_fail:
        spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);

        return rc;
}

static int pm8xxx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        int rc;
        u8 value[NUM_8_BIT_RTC_REGS];
        unsigned long secs;
        unsigned int reg;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;

        rc = regmap_bulk_read(rtc_dd->regmap, regs->read, value, sizeof(value));
        if (rc) {
                dev_err(dev, "RTC read data register failed\n");
                return rc;
        }

        /*
         * Read the LSB again and check if there has been a carry over.
         * If there is, redo the read operation.
         */
        rc = regmap_read(rtc_dd->regmap, regs->read, &reg);
        if (rc < 0) {
                dev_err(dev, "RTC read data register failed\n");
                return rc;
        }

        if (unlikely(reg < value[0])) {
                rc = regmap_bulk_read(rtc_dd->regmap, regs->read,
                                      value, sizeof(value));
                if (rc) {
                        dev_err(dev, "RTC read data register failed\n");
                        return rc;
                }
        }

        secs = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);

        rtc_time_to_tm(secs, tm);

        dev_dbg(dev, "secs = %lu, h:m:s == %d:%d:%d, d/m/y = %d/%d/%d\n",
                secs, tm->tm_hour, tm->tm_min, tm->tm_sec,
                tm->tm_mday, tm->tm_mon, tm->tm_year);

        return 0;
}

static int pm8xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        int rc, i;
        u8 value[NUM_8_BIT_RTC_REGS];
        unsigned int ctrl_reg;
        unsigned long secs, irq_flags;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;

        rtc_tm_to_time(&alarm->time, &secs);

        for (i = 0; i < NUM_8_BIT_RTC_REGS; i++) {
                value[i] = secs & 0xFF;
                secs >>= 8;
        }

        spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);

        rc = regmap_bulk_write(rtc_dd->regmap, regs->alarm_rw, value,
                               sizeof(value));
        if (rc) {
                dev_err(dev, "Write to RTC ALARM register failed\n");
                goto rtc_rw_fail;
        }

        rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
        if (rc)
                goto rtc_rw_fail;

        if (alarm->enabled)
                ctrl_reg |= regs->alarm_en;
        else
                ctrl_reg &= ~regs->alarm_en;

        rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
        if (rc) {
                dev_err(dev, "Write to RTC alarm control register failed\n");
                goto rtc_rw_fail;
        }

        dev_dbg(dev, "Alarm Set for h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
                alarm->time.tm_hour, alarm->time.tm_min,
                alarm->time.tm_sec, alarm->time.tm_mday,
                alarm->time.tm_mon, alarm->time.tm_year);
rtc_rw_fail:
        spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
        return rc;
}

static int pm8xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        int rc;
        u8 value[NUM_8_BIT_RTC_REGS];
        unsigned long secs;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;

        rc = regmap_bulk_read(rtc_dd->regmap, regs->alarm_rw, value,
                              sizeof(value));
        if (rc) {
                dev_err(dev, "RTC alarm time read failed\n");
                return rc;
        }

        secs = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);

        rtc_time_to_tm(secs, &alarm->time);

        rc = rtc_valid_tm(&alarm->time);
        if (rc < 0) {
                dev_err(dev, "Invalid alarm time read from RTC\n");
                return rc;
        }

        dev_dbg(dev, "Alarm set for - h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
                alarm->time.tm_hour, alarm->time.tm_min,
                alarm->time.tm_sec, alarm->time.tm_mday,
                alarm->time.tm_mon, alarm->time.tm_year);

        return 0;
}

static int pm8xxx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
        int rc;
        unsigned long irq_flags;
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
        unsigned int ctrl_reg;

        spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);

        rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
        if (rc)
                goto rtc_rw_fail;

        if (enable)
                ctrl_reg |= regs->alarm_en;
        else
                ctrl_reg &= ~regs->alarm_en;

        rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
        if (rc) {
                dev_err(dev, "Write to RTC control register failed\n");
                goto rtc_rw_fail;
        }

rtc_rw_fail:
        spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
        return rc;
}

static const struct rtc_class_ops pm8xxx_rtc_ops = {
        .read_time      = pm8xxx_rtc_read_time,
        .set_time       = pm8xxx_rtc_set_time,
        .set_alarm      = pm8xxx_rtc_set_alarm,
        .read_alarm     = pm8xxx_rtc_read_alarm,
        .alarm_irq_enable = pm8xxx_rtc_alarm_irq_enable,
};

static irqreturn_t pm8xxx_alarm_trigger(int irq, void *dev_id)
{
        struct pm8xxx_rtc *rtc_dd = dev_id;
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
        unsigned int ctrl_reg;
        int rc;
        unsigned long irq_flags;

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

        spin_lock_irqsave(&rtc_dd->ctrl_reg_lock, irq_flags);

        /* Clear the alarm enable bit */
        rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl, &ctrl_reg);
        if (rc) {
                spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
                goto rtc_alarm_handled;
        }

        ctrl_reg &= ~regs->alarm_en;

        rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl, ctrl_reg);
        if (rc) {
                spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);
                dev_err(rtc_dd->rtc_dev,
                        "Write to alarm control register failed\n");
                goto rtc_alarm_handled;
        }

        spin_unlock_irqrestore(&rtc_dd->ctrl_reg_lock, irq_flags);

        /* Clear RTC alarm register */
        rc = regmap_read(rtc_dd->regmap, regs->alarm_ctrl2, &ctrl_reg);
        if (rc) {
                dev_err(rtc_dd->rtc_dev,
                        "RTC Alarm control2 register read failed\n");
                goto rtc_alarm_handled;
        }

        ctrl_reg |= PM8xxx_RTC_ALARM_CLEAR;
        rc = regmap_write(rtc_dd->regmap, regs->alarm_ctrl2, ctrl_reg);
        if (rc)
                dev_err(rtc_dd->rtc_dev,
                        "Write to RTC Alarm control2 register failed\n");

rtc_alarm_handled:
        return IRQ_HANDLED;
}

static int pm8xxx_rtc_enable(struct pm8xxx_rtc *rtc_dd)
{
        const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
        unsigned int ctrl_reg;
        int rc;

        /* Check if the RTC is on, else turn it on */
        rc = regmap_read(rtc_dd->regmap, regs->ctrl, &ctrl_reg);
        if (rc)
                return rc;

        if (!(ctrl_reg & PM8xxx_RTC_ENABLE)) {
                ctrl_reg |= PM8xxx_RTC_ENABLE;
                rc = regmap_write(rtc_dd->regmap, regs->ctrl, ctrl_reg);
                if (rc)
                        return rc;
        }

        return 0;
}

static const struct pm8xxx_rtc_regs pm8921_regs = {
        .ctrl           = 0x11d,
        .write          = 0x11f,
        .read           = 0x123,
        .alarm_rw       = 0x127,
        .alarm_ctrl     = 0x11d,
        .alarm_ctrl2    = 0x11e,
        .alarm_en       = BIT(1),
};

static const struct pm8xxx_rtc_regs pm8058_regs = {
        .ctrl           = 0x1e8,
        .write          = 0x1ea,
        .read           = 0x1ee,
        .alarm_rw       = 0x1f2,
        .alarm_ctrl     = 0x1e8,
        .alarm_ctrl2    = 0x1e9,
        .alarm_en       = BIT(1),
};

static const struct pm8xxx_rtc_regs pm8941_regs = {
        .ctrl           = 0x6046,
        .write          = 0x6040,
        .read           = 0x6048,
        .alarm_rw       = 0x6140,
        .alarm_ctrl     = 0x6146,
        .alarm_ctrl2    = 0x6148,
        .alarm_en       = BIT(7),
};

/*
 * Hardcoded RTC bases until IORESOURCE_REG mapping is figured out
 */
static const struct of_device_id pm8xxx_id_table[] = {
        { .compatible = "qcom,pm8921-rtc", .data = &pm8921_regs },
        { .compatible = "qcom,pm8018-rtc", .data = &pm8921_regs },
        { .compatible = "qcom,pm8058-rtc", .data = &pm8058_regs },
        { .compatible = "qcom,pm8941-rtc", .data = &pm8941_regs },
        { },
};
MODULE_DEVICE_TABLE(of, pm8xxx_id_table);

static int pm8xxx_rtc_probe(struct platform_device *pdev)
{
        int rc;
        struct pm8xxx_rtc *rtc_dd;
        const struct of_device_id *match;

        match = of_match_node(pm8xxx_id_table, pdev->dev.of_node);
        if (!match)
                return -ENXIO;

        rtc_dd = devm_kzalloc(&pdev->dev, sizeof(*rtc_dd), GFP_KERNEL);
        if (rtc_dd == NULL)
                return -ENOMEM;

        /* Initialise spinlock to protect RTC control register */
        spin_lock_init(&rtc_dd->ctrl_reg_lock);

        rtc_dd->regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!rtc_dd->regmap) {
                dev_err(&pdev->dev, "Parent regmap unavailable.\n");
                return -ENXIO;
        }

        rtc_dd->rtc_alarm_irq = platform_get_irq(pdev, 0);
        if (rtc_dd->rtc_alarm_irq < 0) {
                dev_err(&pdev->dev, "Alarm IRQ resource absent!\n");
                return -ENXIO;
        }

        rtc_dd->allow_set_time = of_property_read_bool(pdev->dev.of_node,
                                                      "allow-set-time");

        rtc_dd->regs = match->data;
        rtc_dd->rtc_dev = &pdev->dev;

        rc = pm8xxx_rtc_enable(rtc_dd);
        if (rc)
                return rc;

        platform_set_drvdata(pdev, rtc_dd);

        device_init_wakeup(&pdev->dev, 1);

        /* Register the RTC device */
        rtc_dd->rtc = devm_rtc_device_register(&pdev->dev, "pm8xxx_rtc",
                                               &pm8xxx_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc_dd->rtc)) {
                dev_err(&pdev->dev, "%s: RTC registration failed (%ld)\n",
                        __func__, PTR_ERR(rtc_dd->rtc));
                return PTR_ERR(rtc_dd->rtc);
        }

        /* Request the alarm IRQ */
        rc = devm_request_any_context_irq(&pdev->dev, rtc_dd->rtc_alarm_irq,
                                          pm8xxx_alarm_trigger,
                                          IRQF_TRIGGER_RISING,
                                          "pm8xxx_rtc_alarm", rtc_dd);
        if (rc < 0) {
                dev_err(&pdev->dev, "Request IRQ failed (%d)\n", rc);
                return rc;
        }

        dev_dbg(&pdev->dev, "Probe success !!\n");

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int pm8xxx_rtc_resume(struct device *dev)
{
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                disable_irq_wake(rtc_dd->rtc_alarm_irq);

        return 0;
}

static int pm8xxx_rtc_suspend(struct device *dev)
{
        struct pm8xxx_rtc *rtc_dd = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                enable_irq_wake(rtc_dd->rtc_alarm_irq);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(pm8xxx_rtc_pm_ops,
                         pm8xxx_rtc_suspend,
                         pm8xxx_rtc_resume);

static struct platform_driver pm8xxx_rtc_driver = {
        .probe          = pm8xxx_rtc_probe,
        .driver = {
                .name           = "rtc-pm8xxx",
                .pm             = &pm8xxx_rtc_pm_ops,
                .of_match_table = pm8xxx_id_table,
        },
};

module_platform_driver(pm8xxx_rtc_driver);

MODULE_ALIAS("platform:rtc-pm8xxx");
MODULE_DESCRIPTION("PMIC8xxx RTC driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Anirudh Ghayal <aghayal@codeaurora.org>");