/*
 * An rtc driver for the Dallas DS1511
 *
 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
 * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
 *
 * 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.
 *
 * Real time clock driver for the Dallas 1511 chip, which also
 * contains a watchdog timer.  There is a tiny amount of code that
 * platform code could use to mess with the watchdog device a little
 * bit, but not a full watchdog driver.
 */

#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/module.h>

enum ds1511reg {
        DS1511_SEC = 0x0,
        DS1511_MIN = 0x1,
        DS1511_HOUR = 0x2,
        DS1511_DOW = 0x3,
        DS1511_DOM = 0x4,
        DS1511_MONTH = 0x5,
        DS1511_YEAR = 0x6,
        DS1511_CENTURY = 0x7,
        DS1511_AM1_SEC = 0x8,
        DS1511_AM2_MIN = 0x9,
        DS1511_AM3_HOUR = 0xa,
        DS1511_AM4_DATE = 0xb,
        DS1511_WD_MSEC = 0xc,
        DS1511_WD_SEC = 0xd,
        DS1511_CONTROL_A = 0xe,
        DS1511_CONTROL_B = 0xf,
        DS1511_RAMADDR_LSB = 0x10,
        DS1511_RAMDATA = 0x13
};

#define DS1511_BLF1     0x80
#define DS1511_BLF2     0x40
#define DS1511_PRS      0x20
#define DS1511_PAB      0x10
#define DS1511_TDF      0x08
#define DS1511_KSF      0x04
#define DS1511_WDF      0x02
#define DS1511_IRQF     0x01
#define DS1511_TE       0x80
#define DS1511_CS       0x40
#define DS1511_BME      0x20
#define DS1511_TPE      0x10
#define DS1511_TIE      0x08
#define DS1511_KIE      0x04
#define DS1511_WDE      0x02
#define DS1511_WDS      0x01
#define DS1511_RAM_MAX  0x100

#define RTC_CMD         DS1511_CONTROL_B
#define RTC_CMD1        DS1511_CONTROL_A

#define RTC_ALARM_SEC   DS1511_AM1_SEC
#define RTC_ALARM_MIN   DS1511_AM2_MIN
#define RTC_ALARM_HOUR  DS1511_AM3_HOUR
#define RTC_ALARM_DATE  DS1511_AM4_DATE

#define RTC_SEC         DS1511_SEC
#define RTC_MIN         DS1511_MIN
#define RTC_HOUR        DS1511_HOUR
#define RTC_DOW         DS1511_DOW
#define RTC_DOM         DS1511_DOM
#define RTC_MON         DS1511_MONTH
#define RTC_YEAR        DS1511_YEAR
#define RTC_CENTURY     DS1511_CENTURY

#define RTC_TIE DS1511_TIE
#define RTC_TE  DS1511_TE

struct rtc_plat_data {
        struct rtc_device *rtc;
        void __iomem *ioaddr;           /* virtual base address */
        int irq;
        unsigned int irqen;
        int alrm_sec;
        int alrm_min;
        int alrm_hour;
        int alrm_mday;
        spinlock_t lock;
};

static DEFINE_SPINLOCK(ds1511_lock);

static __iomem char *ds1511_base;
static u32 reg_spacing = 1;

static noinline void
rtc_write(uint8_t val, uint32_t reg)
{
        writeb(val, ds1511_base + (reg * reg_spacing));
}

static inline void
rtc_write_alarm(uint8_t val, enum ds1511reg reg)
{
        rtc_write((val | 0x80), reg);
}

static noinline uint8_t
rtc_read(enum ds1511reg reg)
{
        return readb(ds1511_base + (reg * reg_spacing));
}

static inline void
rtc_disable_update(void)
{
        rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
}

static void
rtc_enable_update(void)
{
        rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
}

/*
 * #define DS1511_WDOG_RESET_SUPPORT
 *
 * Uncomment this if you want to use these routines in
 * some platform code.
 */
#ifdef DS1511_WDOG_RESET_SUPPORT
/*
 * just enough code to set the watchdog timer so that it
 * will reboot the system
 */
void
ds1511_wdog_set(unsigned long deciseconds)
{
        /*
         * the wdog timer can take 99.99 seconds
         */
        deciseconds %= 10000;
        /*
         * set the wdog values in the wdog registers
         */
        rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
        rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
        /*
         * set wdog enable and wdog 'steering' bit to issue a reset
         */
        rtc_write(rtc_read(RTC_CMD) | DS1511_WDE | DS1511_WDS, RTC_CMD);
}

void
ds1511_wdog_disable(void)
{
        /*
         * clear wdog enable and wdog 'steering' bits
         */
        rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
        /*
         * clear the wdog counter
         */
        rtc_write(0, DS1511_WD_MSEC);
        rtc_write(0, DS1511_WD_SEC);
}
#endif

/*
 * set the rtc chip's idea of the time.
 * stupidly, some callers call with year unmolested;
 * and some call with  year = year - 1900.  thanks.
 */
static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
{
        u8 mon, day, dow, hrs, min, sec, yrs, cen;
        unsigned long flags;

        /*
         * won't have to change this for a while
         */
        if (rtc_tm->tm_year < 1900)
                rtc_tm->tm_year += 1900;

        if (rtc_tm->tm_year < 1970)
                return -EINVAL;

        yrs = rtc_tm->tm_year % 100;
        cen = rtc_tm->tm_year / 100;
        mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
        day = rtc_tm->tm_mday;
        dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
        hrs = rtc_tm->tm_hour;
        min = rtc_tm->tm_min;
        sec = rtc_tm->tm_sec;

        if ((mon > 12) || (day == 0))
                return -EINVAL;

        if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year))
                return -EINVAL;

        if ((hrs >= 24) || (min >= 60) || (sec >= 60))
                return -EINVAL;

        /*
         * each register is a different number of valid bits
         */
        sec = bin2bcd(sec) & 0x7f;
        min = bin2bcd(min) & 0x7f;
        hrs = bin2bcd(hrs) & 0x3f;
        day = bin2bcd(day) & 0x3f;
        mon = bin2bcd(mon) & 0x1f;
        yrs = bin2bcd(yrs) & 0xff;
        cen = bin2bcd(cen) & 0xff;

        spin_lock_irqsave(&ds1511_lock, flags);
        rtc_disable_update();
        rtc_write(cen, RTC_CENTURY);
        rtc_write(yrs, RTC_YEAR);
        rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
        rtc_write(day, RTC_DOM);
        rtc_write(hrs, RTC_HOUR);
        rtc_write(min, RTC_MIN);
        rtc_write(sec, RTC_SEC);
        rtc_write(dow, RTC_DOW);
        rtc_enable_update();
        spin_unlock_irqrestore(&ds1511_lock, flags);

        return 0;
}

static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
{
        unsigned int century;
        unsigned long flags;

        spin_lock_irqsave(&ds1511_lock, flags);
        rtc_disable_update();

        rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
        rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
        rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
        rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
        rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
        rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
        rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
        century = rtc_read(RTC_CENTURY);

        rtc_enable_update();
        spin_unlock_irqrestore(&ds1511_lock, flags);

        rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
        rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
        rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
        rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
        rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
        rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
        rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
        century = bcd2bin(century) * 100;

        /*
         * Account for differences between how the RTC uses the values
         * and how they are defined in a struct rtc_time;
         */
        century += rtc_tm->tm_year;
        rtc_tm->tm_year = century - 1900;

        rtc_tm->tm_mon--;

        if (rtc_valid_tm(rtc_tm) < 0) {
                dev_err(dev, "retrieved date/time is not valid.\n");
                rtc_time_to_tm(0, rtc_tm);
        }
        return 0;
}

/*
 * write the alarm register settings
 *
 * we only have the use to interrupt every second, otherwise
 * known as the update interrupt, or the interrupt if the whole
 * date/hours/mins/secs matches.  the ds1511 has many more
 * permutations, but the kernel doesn't.
 */
static void
ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
{
        unsigned long flags;

        spin_lock_irqsave(&pdata->lock, flags);
        rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
               0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
               RTC_ALARM_DATE);
        rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
               0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
               RTC_ALARM_HOUR);
        rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
               0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
               RTC_ALARM_MIN);
        rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
               0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
               RTC_ALARM_SEC);
        rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
        rtc_read(RTC_CMD1);     /* clear interrupts */
        spin_unlock_irqrestore(&pdata->lock, flags);
}

static int
ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

        if (pdata->irq <= 0)
                return -EINVAL;

        pdata->alrm_mday = alrm->time.tm_mday;
        pdata->alrm_hour = alrm->time.tm_hour;
        pdata->alrm_min = alrm->time.tm_min;
        pdata->alrm_sec = alrm->time.tm_sec;
        if (alrm->enabled)
                pdata->irqen |= RTC_AF;

        ds1511_rtc_update_alarm(pdata);
        return 0;
}

static int
ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

        if (pdata->irq <= 0)
                return -EINVAL;

        alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
        alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
        alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
        alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
        alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
        return 0;
}

static irqreturn_t
ds1511_interrupt(int irq, void *dev_id)
{
        struct platform_device *pdev = dev_id;
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
        unsigned long events = 0;

        spin_lock(&pdata->lock);
        /*
         * read and clear interrupt
         */
        if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
                events = RTC_IRQF;
                if (rtc_read(RTC_ALARM_SEC) & 0x80)
                        events |= RTC_UF;
                else
                        events |= RTC_AF;
                rtc_update_irq(pdata->rtc, 1, events);
        }
        spin_unlock(&pdata->lock);
        return events ? IRQ_HANDLED : IRQ_NONE;
}

static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

        if (pdata->irq <= 0)
                return -EINVAL;
        if (enabled)
                pdata->irqen |= RTC_AF;
        else
                pdata->irqen &= ~RTC_AF;
        ds1511_rtc_update_alarm(pdata);
        return 0;
}

static const struct rtc_class_ops ds1511_rtc_ops = {
        .read_time              = ds1511_rtc_read_time,
        .set_time               = ds1511_rtc_set_time,
        .read_alarm             = ds1511_rtc_read_alarm,
        .set_alarm              = ds1511_rtc_set_alarm,
        .alarm_irq_enable       = ds1511_rtc_alarm_irq_enable,
};

static ssize_t
ds1511_nvram_read(struct file *filp, struct kobject *kobj,
                  struct bin_attribute *ba,
                  char *buf, loff_t pos, size_t size)
{
        ssize_t count;

        rtc_write(pos, DS1511_RAMADDR_LSB);
        for (count = 0; count < size; count++)
                *buf++ = rtc_read(DS1511_RAMDATA);

        return count;
}

static ssize_t
ds1511_nvram_write(struct file *filp, struct kobject *kobj,
                   struct bin_attribute *bin_attr,
                   char *buf, loff_t pos, size_t size)
{
        ssize_t count;

        rtc_write(pos, DS1511_RAMADDR_LSB);
        for (count = 0; count < size; count++)
                rtc_write(*buf++, DS1511_RAMDATA);

        return count;
}

static struct bin_attribute ds1511_nvram_attr = {
        .attr = {
                .name = "nvram",
                .mode = S_IRUGO | S_IWUSR,
        },
        .size = DS1511_RAM_MAX,
        .read = ds1511_nvram_read,
        .write = ds1511_nvram_write,
};

static int ds1511_rtc_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct rtc_plat_data *pdata;
        int ret = 0;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        ds1511_base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(ds1511_base))
                return PTR_ERR(ds1511_base);
        pdata->ioaddr = ds1511_base;
        pdata->irq = platform_get_irq(pdev, 0);

        /*
         * turn on the clock and the crystal, etc.
         */
        rtc_write(DS1511_BME, RTC_CMD);
        rtc_write(0, RTC_CMD1);
        /*
         * clear the wdog counter
         */
        rtc_write(0, DS1511_WD_MSEC);
        rtc_write(0, DS1511_WD_SEC);
        /*
         * start the clock
         */
        rtc_enable_update();

        /*
         * check for a dying bat-tree
         */
        if (rtc_read(RTC_CMD1) & DS1511_BLF1)
                dev_warn(&pdev->dev, "voltage-low detected.\n");

        spin_lock_init(&pdata->lock);
        platform_set_drvdata(pdev, pdata);

        pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
                                              &ds1511_rtc_ops, THIS_MODULE);
        if (IS_ERR(pdata->rtc))
                return PTR_ERR(pdata->rtc);

        /*
         * if the platform has an interrupt in mind for this device,
         * then by all means, set it
         */
        if (pdata->irq > 0) {
                rtc_read(RTC_CMD1);
                if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
                        IRQF_SHARED, pdev->name, pdev) < 0) {

                        dev_warn(&pdev->dev, "interrupt not available.\n");
                        pdata->irq = 0;
                }
        }

        ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
        if (ret)
                dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n",
                        ds1511_nvram_attr.attr.name);

        return 0;
}

static int ds1511_rtc_remove(struct platform_device *pdev)
{
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

        sysfs_remove_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
        if (pdata->irq > 0) {
                /*
                 * disable the alarm interrupt
                 */
                rtc_write(rtc_read(RTC_CMD) & ~RTC_TIE, RTC_CMD);
                rtc_read(RTC_CMD1);
        }
        return 0;
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:ds1511");

static struct platform_driver ds1511_rtc_driver = {
        .probe          = ds1511_rtc_probe,
        .remove         = ds1511_rtc_remove,
        .driver         = {
                .name   = "ds1511",
        },
};

module_platform_driver(ds1511_rtc_driver);

MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
MODULE_LICENSE("GPL");