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ip27-rtc.c

/*
 *    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/bcd.h>
#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 <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>
#include <asm/sn/sn_private.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      */
      {
            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;

            sec = BIN2BCD(sec);
            min = BIN2BCD(min);
            hrs = BIN2BCD(hrs);
            day = BIN2BCD(day);
            mon = BIN2BCD(mon);
            yrs = BIN2BCD(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)
{
      /*
       * Turn off all interrupts once the device is no longer
       * in use, and clear the data.
       */

      spin_lock_irq(&rtc_lock);
      rtc_status &= ~RTC_IS_OPEN;
      spin_unlock_irq(&rtc_lock);

      return 0;
}

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

static const struct file_operations rtc_fops = {
      .owner            = THIS_MODULE,
      .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)
{
      rtc = (struct m48t35_rtc *)
      (KL_CONFIG_CH_CONS_INFO(master_nasid)->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);

      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_mon = BCD2BIN(rtc_tm->tm_mon);
      rtc_tm->tm_year = BCD2BIN(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--;
}

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