/*
 * DS1286 Real Time Clock interface for Linux
 *
 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
 *
 * Based on code written by Paul Gortmaker.
 *
 * This driver allows use of the real time clock (built into nearly all
 * computers) from user space. It exports the /dev/rtc interface supporting
 * various ioctl() and also the /proc/rtc pseudo-file for status
 * information.
 *
 * The ioctls can be used to set the interrupt behaviour and generation rate
 * from the RTC via IRQ 8. Then the /dev/rtc interface can be used to make
 * use of these timer interrupts, be they interval or alarm based.
 *
 * The /dev/rtc interface will block on reads until an interrupt has been
 * received. If a RTC interrupt has already happened, it will output an
 * unsigned long and then block. The output value contains the interrupt
 * status in the low byte and the number of interrupts since the last read
 * in the remaining high bytes. The /dev/rtc interface can also be used with
 * the select(2) call.
 *
 * 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/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/rtc.h>
#include <linux/spinlock.h>

#include <asm/ds1286.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#define DS1286_VERSION          "1.0"

/*
 *      We sponge a minor off of the misc major. No need slurping
 *      up another valuable major dev number for this. If you add
 *      an ioctl, make sure you don't conflict with SPARC's RTC
 *      ioctls.
 */

static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);

static ssize_t ds1286_read(struct file *file, char *buf,
                        size_t count, loff_t *ppos);

static int ds1286_ioctl(struct inode *inode, struct file *file,
                        unsigned int cmd, unsigned long arg);

static unsigned int ds1286_poll(struct file *file, poll_table *wait);

void ds1286_get_alm_time (struct rtc_time *alm_tm);
void ds1286_get_time(struct rtc_time *rtc_tm);
int ds1286_set_time(struct rtc_time *rtc_tm);

void set_rtc_irq_bit(unsigned char bit);
void clear_rtc_irq_bit(unsigned char bit);

static inline unsigned char ds1286_is_updating(void);

static spinlock_t ds1286_lock = SPIN_LOCK_UNLOCKED;

/*
 *      Bits in rtc_status. (7 bits of room for future expansion)
 */

#define RTC_IS_OPEN             0x01    /* means /dev/rtc is in use     */
#define RTC_TIMER_ON            0x02    /* missed irq timer active      */

unsigned char ds1286_status;            /* bitmapped status byte.       */
unsigned long ds1286_freq;              /* Current periodic IRQ rate    */

unsigned char days_in_mo[] =
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/*
 *      Now all the various file operations that we export.
 */

static ssize_t ds1286_read(struct file *file, char *buf,
                           size_t count, loff_t *ppos)
{
        return -EIO;
}

static int ds1286_ioctl(struct inode *inode, struct file *file,
                        unsigned int cmd, unsigned long arg)
{

        struct rtc_time wtime;

        switch (cmd) {
        case RTC_AIE_OFF:       /* Mask alarm int. enab. bit    */
        {
                unsigned int flags;
                unsigned char val;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);
                val = CMOS_READ(RTC_CMD);
                val |=  RTC_TDM;
                CMOS_WRITE(val, RTC_CMD);
                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;
        }
        case RTC_AIE_ON:        /* Allow alarm interrupts.      */
        {
                unsigned int flags;
                unsigned char val;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);
                val = CMOS_READ(RTC_CMD);
                val &=  ~RTC_TDM;
                CMOS_WRITE(val, RTC_CMD);
                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;
        }
        case RTC_WIE_OFF:       /* Mask watchdog int. enab. bit */
        {
                unsigned int flags;
                unsigned char val;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);
                val = CMOS_READ(RTC_CMD);
                val |= RTC_WAM;
                CMOS_WRITE(val, RTC_CMD);
                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;
        }
        case RTC_WIE_ON:        /* Allow watchdog interrupts.   */
        {
                unsigned int flags;
                unsigned char val;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);
                val = CMOS_READ(RTC_CMD);
                val &= ~RTC_WAM;
                CMOS_WRITE(val, RTC_CMD);
                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;
        }
        case RTC_ALM_READ:      /* Read the present alarm time */
        {
                /*
                 * This returns a struct rtc_time. Reading >= 0xc0
                 * means "don't care" or "match all". Only the tm_hour,
                 * tm_min, and tm_sec values are filled in.
                 */
                memset(&wtime, 0, sizeof(struct rtc_time));
                ds1286_get_alm_time(&wtime);
                break;
        }
        case RTC_ALM_SET:       /* Store a time into the alarm */
        {
                /*
                 * This expects a struct rtc_time. Writing 0xff means
                 * "don't care" or "match all". Only the tm_hour,
                 * tm_min and tm_sec are used.
                 */
                unsigned char hrs, min, sec;
                struct rtc_time alm_tm;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
                                   sizeof(struct rtc_time)))
                        return -EFAULT;

                hrs = alm_tm.tm_hour;
                min = alm_tm.tm_min;

                if (hrs >= 24)
                        hrs = 0xff;

                if (min >= 60)
                        min = 0xff;

                BIN_TO_BCD(sec);
                BIN_TO_BCD(min);
                BIN_TO_BCD(hrs);

                spin_lock(&ds1286_lock);
                CMOS_WRITE(hrs, RTC_HOURS_ALARM);
                CMOS_WRITE(min, RTC_MINUTES_ALARM);
                spin_unlock(&ds1286_lock);

                return 0;
        }
        case RTC_RD_TIME:       /* Read the time/date from RTC  */
        {
                memset(&wtime, 0, sizeof(struct rtc_time));
                ds1286_get_time(&wtime);
                break;
        }
        case RTC_SET_TIME:      /* Set the RTC */
        {
                struct rtc_time rtc_tm;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
                                   sizeof(struct rtc_time)))
                        return -EFAULT;

                return ds1286_set_time(&rtc_tm);
        }
        default:
                return -EINVAL;
        }
        return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
}

/*
 *      We enforce only one user at a time here with the open/close.
 *      Also clear the previous interrupt data on an open, and clean
 *      up things on a close.
 */

static int ds1286_open(struct inode *inode, struct file *file)
{
        spin_lock_irq(&ds1286_lock);

        if (ds1286_status & RTC_IS_OPEN)
                goto out_busy;

        ds1286_status |= RTC_IS_OPEN;

        spin_lock_irq(&ds1286_lock);
        return 0;

out_busy:
        spin_lock_irq(&ds1286_lock);
        return -EBUSY;
}

static int ds1286_release(struct inode *inode, struct file *file)
{
        ds1286_status &= ~RTC_IS_OPEN;

        return 0;
}

static unsigned int ds1286_poll(struct file *file, poll_table *wait)
{
        poll_wait(file, &ds1286_wait, wait);

        return 0;
}

/*
 *      The various file operations we support.
 */

static struct file_operations ds1286_fops = {
        .llseek         = no_llseek,
        .read           = ds1286_read,
        .poll           = ds1286_poll,
        .ioctl          = ds1286_ioctl,
        .open           = ds1286_open,
        .release        = ds1286_release,
};

static struct miscdevice ds1286_dev=
{
        .minor  = RTC_MINOR,
        .name   = "rtc",
        .fops   = &ds1286_fops,
};

int __init ds1286_init(void)
{
        printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);
        return misc_register(&ds1286_dev);
}

static char *days[] = {
        "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};

/*
 *      Info exported via "/proc/rtc".
 */
int get_ds1286_status(char *buf)
{
        char *p, *s;
        struct rtc_time tm;
        unsigned char hundredth, month, cmd, amode;

        p = buf;

        ds1286_get_time(&tm);
        hundredth = CMOS_READ(RTC_HUNDREDTH_SECOND);
        BCD_TO_BIN(hundredth);

        p += sprintf(p,
                     "rtc_time\t: %02d:%02d:%02d.%02d\n"
                     "rtc_date\t: %04d-%02d-%02d\n",
                     tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
                     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);

        /*
         * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
         * match any value for that particular field. Values that are
         * greater than a valid time, but less than 0xc0 shouldn't appear.
         */
        ds1286_get_alm_time(&tm);
        p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
        if (tm.tm_hour <= 24)
                p += sprintf(p, "%02d:", tm.tm_hour);
        else
                p += sprintf(p, "**:");

        if (tm.tm_min <= 59)
                p += sprintf(p, "%02d\n", tm.tm_min);
        else
                p += sprintf(p, "**\n");

        month = CMOS_READ(RTC_MONTH);
        p += sprintf(p,
                     "oscillator\t: %s\n"
                     "square_wave\t: %s\n",
                     (month & RTC_EOSC) ? "disabled" : "enabled",
                     (month & RTC_ESQW) ? "disabled" : "enabled");

        amode = ((CMOS_READ(RTC_MINUTES_ALARM) & 0x80) >> 5) |
                ((CMOS_READ(RTC_HOURS_ALARM) & 0x80) >> 6) |
                ((CMOS_READ(RTC_DAY_ALARM) & 0x80) >> 7);
        if (amode == 7)      s = "each minute";
        else if (amode == 3) s = "minutes match";
        else if (amode == 1) s = "hours and minutes match";
        else if (amode == 0) s = "days, hours and minutes match";
        else                 s = "invalid";
        p += sprintf(p, "alarm_mode\t: %s\n", s);

        cmd = CMOS_READ(RTC_CMD);
        p += sprintf(p,
                     "alarm_enable\t: %s\n"
                     "wdog_alarm\t: %s\n"
                     "alarm_mask\t: %s\n"
                     "wdog_alarm_mask\t: %s\n"
                     "interrupt_mode\t: %s\n"
                     "INTB_mode\t: %s_active\n"
                     "interrupt_pins\t: %s\n",
                     (cmd & RTC_TDF) ? "yes" : "no",
                     (cmd & RTC_WAF) ? "yes" : "no",
                     (cmd & RTC_TDM) ? "disabled" : "enabled",
                     (cmd & RTC_WAM) ? "disabled" : "enabled",
                     (cmd & RTC_PU_LVL) ? "pulse" : "level",
                     (cmd & RTC_IBH_LO) ? "low" : "high",
                     (cmd & RTC_IPSW) ? "unswapped" : "swapped");

        return  p - buf;
}

/*
 * Returns true if a clock update is in progress
 */
static inline unsigned char ds1286_is_updating(void)
{
        return CMOS_READ(RTC_CMD) & RTC_TE;
}


void ds1286_get_time(struct rtc_time *rtc_tm)
{
        unsigned char save_control;
        unsigned int flags;
        unsigned long uip_watchdog = jiffies;

        /*
         * read RTC once any update in progress is done. The update
         * can take just over 2ms. We wait 10 to 20ms. There is no need to
         * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
         * If you need to know *exactly* when a second has started, enable
         * periodic update complete interrupts, (via ioctl) and then
         * immediately read /dev/rtc which will block until you get the IRQ.
         * Once the read clears, read the RTC time (again via ioctl). Easy.
         */

        if (ds1286_is_updating() != 0)
                while (jiffies - uip_watchdog < 2*HZ/100)
                        barrier();

        /*
         * Only the values that we read from the RTC are set. We leave
         * tm_wday, tm_yday and tm_isdst untouched. Even though the
         * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
         * by the RTC when initially set to a non-zero value.
         */
        spin_lock_irqsave(&ds1286_lock, flags);
        save_control = CMOS_READ(RTC_CMD);
        CMOS_WRITE((save_control|RTC_TE), RTC_CMD);

        rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
        rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
        rtc_tm->tm_hour = CMOS_READ(RTC_HOURS) & 0x3f;
        rtc_tm->tm_mday = CMOS_READ(RTC_DATE);
        rtc_tm->tm_mon = CMOS_READ(RTC_MONTH) & 0x1f;
        rtc_tm->tm_year = CMOS_READ(RTC_YEAR);

        CMOS_WRITE(save_control, RTC_CMD);
        spin_unlock_irqrestore(&ds1286_lock, flags);

        BCD_TO_BIN(rtc_tm->tm_sec);
        BCD_TO_BIN(rtc_tm->tm_min);
        BCD_TO_BIN(rtc_tm->tm_hour);
        BCD_TO_BIN(rtc_tm->tm_mday);
        BCD_TO_BIN(rtc_tm->tm_mon);
        BCD_TO_BIN(rtc_tm->tm_year);

        /*
         * Account for differences between how the RTC uses the values
         * and how they are defined in a struct rtc_time;
         */
        if (rtc_tm->tm_year < 45)
                rtc_tm->tm_year += 30;
        if ((rtc_tm->tm_year += 40) < 70)
                rtc_tm->tm_year += 100;

        rtc_tm->tm_mon--;
}

int ds1286_set_time(struct rtc_time *rtc_tm)
{
        unsigned char mon, day, hrs, min, sec, leap_yr;
        unsigned char save_control;
        unsigned int yrs, flags;


        yrs = rtc_tm->tm_year + 1900;
        mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
        day = rtc_tm->tm_mday;
        hrs = rtc_tm->tm_hour;
        min = rtc_tm->tm_min;
        sec = rtc_tm->tm_sec;

        if (yrs < 1970)
                return -EINVAL;

        leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));

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

        if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
                return -EINVAL;

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

        if ((yrs -= 1940) > 255)    /* They are unsigned */
                return -EINVAL;

        if (yrs >= 100)
                yrs -= 100;

        BIN_TO_BCD(sec);
        BIN_TO_BCD(min);
        BIN_TO_BCD(hrs);
        BIN_TO_BCD(day);
        BIN_TO_BCD(mon);
        BIN_TO_BCD(yrs);

        spin_lock_irqsave(&ds1286_lock, flags);
        save_control = CMOS_READ(RTC_CMD);
        CMOS_WRITE((save_control|RTC_TE), RTC_CMD);

        CMOS_WRITE(yrs, RTC_YEAR);
        CMOS_WRITE(mon, RTC_MONTH);
        CMOS_WRITE(day, RTC_DATE);
        CMOS_WRITE(hrs, RTC_HOURS);
        CMOS_WRITE(min, RTC_MINUTES);
        CMOS_WRITE(sec, RTC_SECONDS);
        CMOS_WRITE(0, RTC_HUNDREDTH_SECOND);

        CMOS_WRITE(save_control, RTC_CMD);
        spin_unlock_irqrestore(&ds1286_lock, flags);

        return 0;
}

void ds1286_get_alm_time(struct rtc_time *alm_tm)
{
        unsigned char cmd;
        unsigned int flags;

        /*
         * Only the values that we read from the RTC are set. That
         * means only tm_wday, tm_hour, tm_min.
         */
        spin_lock_irqsave(&ds1286_lock, flags);
        alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM) & 0x7f;
        alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM)  & 0x1f;
        alm_tm->tm_wday = CMOS_READ(RTC_DAY_ALARM)    & 0x07;
        cmd = CMOS_READ(RTC_CMD);
        spin_unlock_irqrestore(&ds1286_lock, flags);

        BCD_TO_BIN(alm_tm->tm_min);
        BCD_TO_BIN(alm_tm->tm_hour);
        alm_tm->tm_sec = 0;
}