/*
 * rtc-tps65910.c -- TPS65910 Real Time Clock interface
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
 * Author: Venu Byravarasu <vbyravarasu@nvidia.com>
 *
 * Based on original TI driver rtc-twl.c
 *   Copyright (C) 2007 MontaVista Software, Inc
 *   Author: Alexandre Rusev <source@mvista.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/mfd/tps65910.h>

struct tps65910_rtc {
        struct rtc_device       *rtc;
        int irq;
};

/* Total number of RTC registers needed to set time*/
#define NUM_TIME_REGS   (TPS65910_YEARS - TPS65910_SECONDS + 1)

static int tps65910_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
{
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        u8 val = 0;

        if (enabled)
                val = TPS65910_RTC_INTERRUPTS_IT_ALARM;

        return regmap_write(tps->regmap, TPS65910_RTC_INTERRUPTS, val);
}

/*
 * Gets current tps65910 RTC time and date parameters.
 *
 * The RTC's time/alarm representation is not what gmtime(3) requires
 * Linux to use:
 *
 *  - Months are 1..12 vs Linux 0-11
 *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
 */
static int tps65910_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char rtc_data[NUM_TIME_REGS];
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        int ret;

        /* Copy RTC counting registers to static registers or latches */
        ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
                TPS65910_RTC_CTRL_GET_TIME, TPS65910_RTC_CTRL_GET_TIME);
        if (ret < 0) {
                dev_err(dev, "RTC CTRL reg update failed with err:%d\n", ret);
                return ret;
        }

        ret = regmap_bulk_read(tps->regmap, TPS65910_SECONDS, rtc_data,
                NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "reading from RTC failed with err:%d\n", ret);
                return ret;
        }

        tm->tm_sec = bcd2bin(rtc_data[0]);
        tm->tm_min = bcd2bin(rtc_data[1]);
        tm->tm_hour = bcd2bin(rtc_data[2]);
        tm->tm_mday = bcd2bin(rtc_data[3]);
        tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
        tm->tm_year = bcd2bin(rtc_data[5]) + 100;

        return ret;
}

static int tps65910_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        unsigned char rtc_data[NUM_TIME_REGS];
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        int ret;

        rtc_data[0] = bin2bcd(tm->tm_sec);
        rtc_data[1] = bin2bcd(tm->tm_min);
        rtc_data[2] = bin2bcd(tm->tm_hour);
        rtc_data[3] = bin2bcd(tm->tm_mday);
        rtc_data[4] = bin2bcd(tm->tm_mon + 1);
        rtc_data[5] = bin2bcd(tm->tm_year - 100);

        /* Stop RTC while updating the RTC time registers */
        ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
                TPS65910_RTC_CTRL_STOP_RTC, 0);
        if (ret < 0) {
                dev_err(dev, "RTC stop failed with err:%d\n", ret);
                return ret;
        }

        /* update all the time registers in one shot */
        ret = regmap_bulk_write(tps->regmap, TPS65910_SECONDS, rtc_data,
                NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "rtc_set_time error %d\n", ret);
                return ret;
        }

        /* Start back RTC */
        ret = regmap_update_bits(tps->regmap, TPS65910_RTC_CTRL,
                TPS65910_RTC_CTRL_STOP_RTC, 1);
        if (ret < 0)
                dev_err(dev, "RTC start failed with err:%d\n", ret);

        return ret;
}

/*
 * Gets current tps65910 RTC alarm time.
 */
static int tps65910_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char alarm_data[NUM_TIME_REGS];
        u32 int_val;
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        int ret;

        ret = regmap_bulk_read(tps->regmap, TPS65910_SECONDS, alarm_data,
                NUM_TIME_REGS);
        if (ret < 0) {
                dev_err(dev, "rtc_read_alarm error %d\n", ret);
                return ret;
        }

        alm->time.tm_sec = bcd2bin(alarm_data[0]);
        alm->time.tm_min = bcd2bin(alarm_data[1]);
        alm->time.tm_hour = bcd2bin(alarm_data[2]);
        alm->time.tm_mday = bcd2bin(alarm_data[3]);
        alm->time.tm_mon = bcd2bin(alarm_data[4]) - 1;
        alm->time.tm_year = bcd2bin(alarm_data[5]) + 100;

        ret = regmap_read(tps->regmap, TPS65910_RTC_INTERRUPTS, &int_val);
        if (ret < 0)
                return ret;

        if (int_val & TPS65910_RTC_INTERRUPTS_IT_ALARM)
                alm->enabled = 1;

        return ret;
}

static int tps65910_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        unsigned char alarm_data[NUM_TIME_REGS];
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        int ret;

        ret = tps65910_rtc_alarm_irq_enable(dev, 0);
        if (ret)
                return ret;

        alarm_data[0] = bin2bcd(alm->time.tm_sec);
        alarm_data[1] = bin2bcd(alm->time.tm_min);
        alarm_data[2] = bin2bcd(alm->time.tm_hour);
        alarm_data[3] = bin2bcd(alm->time.tm_mday);
        alarm_data[4] = bin2bcd(alm->time.tm_mon + 1);
        alarm_data[5] = bin2bcd(alm->time.tm_year - 100);

        /* update all the alarm registers in one shot */
        ret = regmap_bulk_write(tps->regmap, TPS65910_ALARM_SECONDS,
                alarm_data, NUM_TIME_REGS);
        if (ret) {
                dev_err(dev, "rtc_set_alarm error %d\n", ret);
                return ret;
        }

        if (alm->enabled)
                ret = tps65910_rtc_alarm_irq_enable(dev, 1);

        return ret;
}

static irqreturn_t tps65910_rtc_interrupt(int irq, void *rtc)
{
        struct device *dev = rtc;
        unsigned long events = 0;
        struct tps65910 *tps = dev_get_drvdata(dev->parent);
        struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);
        int ret;
        u32 rtc_reg;

        ret = regmap_read(tps->regmap, TPS65910_RTC_STATUS, &rtc_reg);
        if (ret)
                return IRQ_NONE;

        if (rtc_reg & TPS65910_RTC_STATUS_ALARM)
                events = RTC_IRQF | RTC_AF;

        ret = regmap_write(tps->regmap, TPS65910_RTC_STATUS, rtc_reg);
        if (ret)
                return IRQ_NONE;

        /* Notify RTC core on event */
        rtc_update_irq(tps_rtc->rtc, 1, events);

        return IRQ_HANDLED;
}

static const struct rtc_class_ops tps65910_rtc_ops = {
        .read_time      = tps65910_rtc_read_time,
        .set_time       = tps65910_rtc_set_time,
        .read_alarm     = tps65910_rtc_read_alarm,
        .set_alarm      = tps65910_rtc_set_alarm,
        .alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
};

static int tps65910_rtc_probe(struct platform_device *pdev)
{
        struct tps65910 *tps65910 = NULL;
        struct tps65910_rtc *tps_rtc = NULL;
        int ret;
        int irq;
        u32 rtc_reg;

        tps65910 = dev_get_drvdata(pdev->dev.parent);

        tps_rtc = devm_kzalloc(&pdev->dev, sizeof(struct tps65910_rtc),
                        GFP_KERNEL);
        if (!tps_rtc)
                return -ENOMEM;

        /* Clear pending interrupts */
        ret = regmap_read(tps65910->regmap, TPS65910_RTC_STATUS, &rtc_reg);
        if (ret < 0)
                return ret;

        ret = regmap_write(tps65910->regmap, TPS65910_RTC_STATUS, rtc_reg);
        if (ret < 0)
                return ret;

        dev_dbg(&pdev->dev, "Enabling rtc-tps65910.\n");

        /* Enable RTC digital power domain */
        ret = regmap_update_bits(tps65910->regmap, TPS65910_DEVCTRL,
                DEVCTRL_RTC_PWDN_MASK, 0 << DEVCTRL_RTC_PWDN_SHIFT);
        if (ret < 0)
                return ret;

        rtc_reg = TPS65910_RTC_CTRL_STOP_RTC;
        ret = regmap_write(tps65910->regmap, TPS65910_RTC_CTRL, rtc_reg);
        if (ret < 0)
                return ret;

        platform_set_drvdata(pdev, tps_rtc);

        irq  = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                dev_warn(&pdev->dev, "Wake up is not possible as irq = %d\n",
                        irq);
                return -ENXIO;
        }

        ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
                tps65910_rtc_interrupt, IRQF_TRIGGER_LOW | IRQF_EARLY_RESUME,
                dev_name(&pdev->dev), &pdev->dev);
        if (ret < 0) {
                dev_err(&pdev->dev, "IRQ is not free.\n");
                return ret;
        }
        tps_rtc->irq = irq;
        device_set_wakeup_capable(&pdev->dev, 1);

        tps_rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
                &tps65910_rtc_ops, THIS_MODULE);
        if (IS_ERR(tps_rtc->rtc)) {
                ret = PTR_ERR(tps_rtc->rtc);
                dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
                return ret;
        }

        return 0;
}

/*
 * Disable tps65910 RTC interrupts.
 * Sets status flag to free.
 */
static int tps65910_rtc_remove(struct platform_device *pdev)
{
        tps65910_rtc_alarm_irq_enable(&pdev->dev, 0);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tps65910_rtc_suspend(struct device *dev)
{
        struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                enable_irq_wake(tps_rtc->irq);
        return 0;
}

static int tps65910_rtc_resume(struct device *dev)
{
        struct tps65910_rtc *tps_rtc = dev_get_drvdata(dev);

        if (device_may_wakeup(dev))
                disable_irq_wake(tps_rtc->irq);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(tps65910_rtc_pm_ops, tps65910_rtc_suspend,
                        tps65910_rtc_resume);

static struct platform_driver tps65910_rtc_driver = {
        .probe          = tps65910_rtc_probe,
        .remove         = tps65910_rtc_remove,
        .driver         = {
                .name   = "tps65910-rtc",
                .pm     = &tps65910_rtc_pm_ops,
        },
};

module_platform_driver(tps65910_rtc_driver);
MODULE_ALIAS("platform:rtc-tps65910");
MODULE_AUTHOR("Venu Byravarasu <vbyravarasu@nvidia.com>");
MODULE_LICENSE("GPL");