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/*

 *      Driver for the SGS-Thomson M48T35 Timekeeper RAM chip

 *

 *      Real Time Clock interface for Linux

 *

 *      TODO: Implement periodic interrupts.

 *

 *      Copyright (C) 2000 Silicon Graphics, Inc.

 *      Written by Ulf Carlsson (ulfc@engr.sgi.com)

 *

 *      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.

 *

 *      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.

 *

 */

#define RTC_VERSION             "1.09b"

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/types.h>

#include <linux/miscdevice.h>

#include <linux/ioport.h>

#include <linux/fcntl.h>

#include <linux/rtc.h>

#include <linux/init.h>

#include <linux/poll.h>

#include <linux/proc_fs.h>

#include <linux/smp_lock.h>

#include <asm/m48t35.h>

#include <asm/sn/ioc3.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <asm/sn/klconfig.h>

#include <asm/sn/sn0/ip27.h>

#include <asm/sn/sn0/hub.h>

static int rtc_ioctl(struct inode *inode, struct file *file,

                     unsigned int cmd, unsigned long arg);

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

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

static void get_rtc_time(struct rtc_time *rtc_tm);

/*

 *      Bits in rtc_status. (6 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 rtc_status;        /* bitmapped status byte.       */

static unsigned long rtc_freq;  /* Current periodic IRQ rate    */

static struct m48t35_rtc *rtc;

/*

 *      If this driver ever becomes modularised, it will be really nice

 *      to make the epoch retain its value across module reload...

 */

static unsigned long epoch = 1970;      /* year corresponding to 0x00   */

static const unsigned char days_in_mo[] =

{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,

                     unsigned long arg)

{

        struct rtc_time wtime;

        switch (cmd) {

        case RTC_RD_TIME:       /* Read the time/date from RTC  */

        {

                memset(&wtime, 0, sizeof(struct rtc_time));

                get_rtc_time(&wtime);

                break;

        }

        case RTC_SET_TIME:      /* Set the RTC */

        {

                struct rtc_time rtc_tm;

                unsigned char mon, day, hrs, min, sec, leap_yr;

                unsigned int yrs;

                if (!capable(CAP_SYS_TIME))

                        return -EACCES;

                if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,

                                   sizeof(struct rtc_time)))

                        return -EFAULT;

                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 -= epoch) > 255)    /* They are unsigned */

                        return -EINVAL;

                if (yrs > 169) {

                        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_irq(&rtc_lock);

                rtc->control |= M48T35_RTC_SET;

                rtc->year = yrs;

                rtc->month = mon;

                rtc->date = day;

                rtc->hour = hrs;

                rtc->min = min;

                rtc->sec = sec;

                rtc->control &= ~M48T35_RTC_SET;

                spin_unlock_irq(&rtc_lock);

                return 0;

        }

        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 rtc_open(struct inode *inode, struct file *file)

{

        spin_lock_irq(&rtc_lock);

        if (rtc_status & RTC_IS_OPEN) {

                spin_unlock_irq(&rtc_lock);

                return -EBUSY;

        }

        rtc_status |= RTC_IS_OPEN;

        spin_unlock_irq(&rtc_lock);

        return 0;

}

static int rtc_release(struct inode *inode, struct file *file)

{

        /*

         * No need for locking -- nobody else can do anything until this rmw

         * is committed, and no timer is running.

         */

        rtc_status &= ~RTC_IS_OPEN;

        return 0;

}

/*

 *      The various file operations we support.

 */

static struct file_operations rtc_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .ioctl          = rtc_ioctl,

        .open           = rtc_open,

        .release        = rtc_release,

};

static struct miscdevice rtc_dev=

{

        RTC_MINOR,

        "rtc",

        &rtc_fops

};

static int __init rtc_init(void)

{

        nasid_t nid;

        nid = get_nasid();

        rtc = (struct m48t35_rtc *)

            (KL_CONFIG_CH_CONS_INFO(nid)->memory_base + IOC3_BYTEBUS_DEV0);

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

        if (misc_register(&rtc_dev)) {

                printk(KERN_ERR "rtc: cannot register misc device.\n");

                return -ENODEV;

        }

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

                printk(KERN_ERR "rtc: cannot create /proc/rtc.\n");

                misc_deregister(&rtc_dev);

                return -ENOENT;

        }

        rtc_freq = 1024;

        return 0;

}

static void __exit rtc_exit (void)

{

        /* interrupts and timer disabled at this point by rtc_release */

        remove_proc_entry ("rtc", NULL);

        misc_deregister(&rtc_dev);

}

module_init(rtc_init);

module_exit(rtc_exit);

/*

 *      Info exported via "/proc/rtc".

 */

static int rtc_get_status(char *buf)

{

        char *p;

        struct rtc_time tm;

        /*

         * Just emulate the standard /proc/rtc

         */

        p = buf;

        get_rtc_time(&tm);

        /*

         * There is no way to tell if the luser has the RTC set for local

         * time or for Universal Standard Time (GMT). Probably local though.

         */

        p += sprintf(p,

                     "rtc_time\t: %02d:%02d:%02d\n"

                     "rtc_date\t: %04d-%02d-%02d\n"

                     "rtc_epoch\t: %04lu\n"

                     "24hr\t\t: yes\n",

                     tm.tm_hour, tm.tm_min, tm.tm_sec,

                     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);

        return  p - buf;

}

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

                                 int count, int *eof, void *data)

{

        int len = rtc_get_status(page);

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

        *start = page + off;

        len -= off;

        if (len>count) len = count;

        if (len<0) len = 0;

        return len;

}

static void get_rtc_time(struct rtc_time *rtc_tm)

{

        /*

         * Do we need to wait for the last update to finish?

         */

        /*

         * 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_irq(&rtc_lock);

        rtc->control |= M48T35_RTC_READ;

        rtc_tm->tm_sec = rtc->sec;

        rtc_tm->tm_min = rtc->min;

        rtc_tm->tm_hour = rtc->hour;

        rtc_tm->tm_mday = rtc->date;

        rtc_tm->tm_mon = rtc->month;

        rtc_tm->tm_year = rtc->year;

        rtc->control &= ~M48T35_RTC_READ;

        spin_unlock_irq(&rtc_lock);

        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 += (epoch - 1900)) <= 69)

                rtc_tm->tm_year += 100;

        rtc_tm->tm_mon--;

}