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/*

 * 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/ds1286.h>

#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 <linux/bcd.h>

#include <linux/proc_fs.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);

static void ds1286_get_alm_time (struct rtc_time *alm_tm);

static void ds1286_get_time(struct rtc_time *rtc_tm);

static int ds1286_set_time(struct rtc_time *rtc_tm);

static inline unsigned char ds1286_is_updating(void);

static DEFINE_SPINLOCK(ds1286_lock);

static int ds1286_read_proc(char *page, char **start, off_t off,

                            int count, int *eof, void *data);

/*

 *      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      */

static unsigned char ds1286_status;     /* bitmapped status byte.       */

static 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 long flags;

                unsigned char val;

                if (!capable(CAP_SYS_TIME))

                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);

                val = rtc_read(RTC_CMD);

                val |=  RTC_TDM;

                rtc_write(val, RTC_CMD);

                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;

        }

        case RTC_AIE_ON:        /* Allow alarm interrupts.      */

        {

                unsigned long flags;

                unsigned char val;

                if (!capable(CAP_SYS_TIME))

                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);

                val = rtc_read(RTC_CMD);

                val &=  ~RTC_TDM;

                rtc_write(val, RTC_CMD);

                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;

        }

        case RTC_WIE_OFF:       /* Mask watchdog int. enab. bit */

        {

                unsigned long flags;

                unsigned char val;

                if (!capable(CAP_SYS_TIME))

                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);

                val = rtc_read(RTC_CMD);

                val |= RTC_WAM;

                rtc_write(val, RTC_CMD);

                spin_unlock_irqrestore(&ds1286_lock, flags);

                return 0;

        }

        case RTC_WIE_ON:        /* Allow watchdog interrupts.   */

        {

                unsigned long flags;

                unsigned char val;

                if (!capable(CAP_SYS_TIME))

                        return -EACCES;

                spin_lock_irqsave(&ds1286_lock, flags);

                val = rtc_read(RTC_CMD);

                val &= ~RTC_WAM;

                rtc_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(wtime));

                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;

                sec = alm_tm.tm_sec;

                if (hrs >= 24)

                        hrs = 0xff;

                if (min >= 60)

                        min = 0xff;

                if (sec != 0)

                        return -EINVAL;

                min = BIN2BCD(min);

                min = BIN2BCD(hrs);

                spin_lock(&ds1286_lock);

                rtc_write(hrs, RTC_HOURS_ALARM);

                rtc_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(wtime));

                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_unlock_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 const 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,

};

static int __init ds1286_init(void)

{

        int err;

        printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);

        err = misc_register(&ds1286_dev);

        if (err)

                goto out;

        if (!create_proc_read_entry("driver/rtc", 0, 0, ds1286_read_proc, NULL)) {

                err = -ENOMEM;

                goto out_deregister;

        }

        return 0;

out_deregister:

        misc_deregister(&ds1286_dev);

out:

        return err;

}

static void __exit ds1286_exit(void)

{

        remove_proc_entry("driver/rtc", NULL);

        misc_deregister(&ds1286_dev);

}

static char *days[] = {

        "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"

};

/*

 *      Info exported via "/proc/rtc".

 */

static int ds1286_proc_output(char *buf)

{

        char *p, *s;

        struct rtc_time tm;

        unsigned char hundredth, month, cmd, amode;

        p = buf;

        ds1286_get_time(&tm);

        hundredth = rtc_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 = rtc_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 = ((rtc_read(RTC_MINUTES_ALARM) & 0x80) >> 5) |

                ((rtc_read(RTC_HOURS_ALARM) & 0x80) >> 6) |

                ((rtc_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 = rtc_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;

}

static int ds1286_read_proc(char *page, char **start, off_t off,

                         int count, int *eof, void *data)

{

        int len = ds1286_proc_output (page);

        if (len <= off+count) *eof = 1;

        *start = page + off;

        len -= off;

        if (len>count)

                len = count;

        if (len<0)

                len = 0;

        return len;

}

/*

 * Returns true if a clock update is in progress

 */

static inline unsigned char ds1286_is_updating(void)

{

        return rtc_read(RTC_CMD) & RTC_TE;

}

static void ds1286_get_time(struct rtc_time *rtc_tm)

{

        unsigned char save_control;

        unsigned long 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 = rtc_read(RTC_CMD);

        rtc_write((save_control|RTC_TE), RTC_CMD);

        rtc_tm->tm_sec = rtc_read(RTC_SECONDS);

        rtc_tm->tm_min = rtc_read(RTC_MINUTES);

        rtc_tm->tm_hour = rtc_read(RTC_HOURS) & 0x3f;

        rtc_tm->tm_mday = rtc_read(RTC_DATE);

        rtc_tm->tm_mon = rtc_read(RTC_MONTH) & 0x1f;

        rtc_tm->tm_year = rtc_read(RTC_YEAR);

        rtc_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--;

}

static 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;

        unsigned long 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 = rtc_read(RTC_CMD);

        rtc_write((save_control|RTC_TE), RTC_CMD);

        rtc_write(yrs, RTC_YEAR);

        rtc_write(mon, RTC_MONTH);

        rtc_write(day, RTC_DATE);

        rtc_write(hrs, RTC_HOURS);

        rtc_write(min, RTC_MINUTES);

        rtc_write(sec, RTC_SECONDS);

        rtc_write(0, RTC_HUNDREDTH_SECOND);

        rtc_write(save_control, RTC_CMD);

        spin_unlock_irqrestore(&ds1286_lock, flags);

        return 0;

}

static void ds1286_get_alm_time(struct rtc_time *alm_tm)

{

        unsigned char cmd;

        unsigned long 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 = rtc_read(RTC_MINUTES_ALARM) & 0x7f;

        alm_tm->tm_hour = rtc_read(RTC_HOURS_ALARM)  & 0x1f;

        alm_tm->tm_wday = rtc_read(RTC_DAY_ALARM)    & 0x07;

        cmd = rtc_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;

}

module_init(ds1286_init);

module_exit(ds1286_exit);

MODULE_AUTHOR("Ralf Baechle");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(RTC_MINOR);