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rtc.c

/*
 *    Real Time Clock interface for Linux on the BVME6000
 *
 * Based on the PC driver by Paul Gortmaker.
 */

#define RTC_VERSION           "1.00"

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/capability.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/mc146818rtc.h>      /* For struct rtc_time and ioctls, etc */
#include <linux/bcd.h>
#include <asm/bvme6000hw.h>

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

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

static atomic_t rtc_status = ATOMIC_INIT(1);

static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
      volatile RtcPtr_t rtc = (RtcPtr_t)BVME_RTC_BASE;
      unsigned char msr;
      unsigned long flags;
      struct rtc_time wtime;
      void __user *argp = (void __user *)arg;

      switch (cmd) {
      case RTC_RD_TIME: /* Read the time/date from RTC      */
      {
            local_irq_save(flags);
            /* Ensure clock and real-time-mode-register are accessible */
            msr = rtc->msr & 0xc0;
            rtc->msr = 0x40;
            memset(&wtime, 0, sizeof(struct rtc_time));
            do {
                  wtime.tm_sec =  bcd2bin(rtc->bcd_sec);
                  wtime.tm_min =  bcd2bin(rtc->bcd_min);
                  wtime.tm_hour = bcd2bin(rtc->bcd_hr);
                  wtime.tm_mday =  bcd2bin(rtc->bcd_dom);
                  wtime.tm_mon =  bcd2bin(rtc->bcd_mth)-1;
                  wtime.tm_year = bcd2bin(rtc->bcd_year);
                  if (wtime.tm_year < 70)
                        wtime.tm_year += 100;
                  wtime.tm_wday = bcd2bin(rtc->bcd_dow)-1;
            } while (wtime.tm_sec != bcd2bin(rtc->bcd_sec));
            rtc->msr = msr;
            local_irq_restore(flags);
            return copy_to_user(argp, &wtime, sizeof wtime) ?
                                                -EFAULT : 0;
      }
      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_ADMIN))
                  return -EACCES;

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

            yrs = rtc_tm.tm_year;
            if (yrs < 1900)
                  yrs += 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;

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

            if ((mon > 12) || (mon < 1) || (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 >= 2070)
                  return -EINVAL;

            local_irq_save(flags);
            /* Ensure clock and real-time-mode-register are accessible */
            msr = rtc->msr & 0xc0;
            rtc->msr = 0x40;

            rtc->t0cr_rtmr = yrs%4;
            rtc->bcd_tenms = 0;
            rtc->bcd_sec   = bin2bcd(sec);
            rtc->bcd_min   = bin2bcd(min);
            rtc->bcd_hr    = bin2bcd(hrs);
            rtc->bcd_dom   = bin2bcd(day);
            rtc->bcd_mth   = bin2bcd(mon);
            rtc->bcd_year  = bin2bcd(yrs%100);
            if (rtc_tm.tm_wday >= 0)
                  rtc->bcd_dow = bin2bcd(rtc_tm.tm_wday+1);
            rtc->t0cr_rtmr = yrs%4 | 0x08;

            rtc->msr = msr;
            local_irq_restore(flags);
            return 0;
      }
      default:
            return -EINVAL;
      }
}

/*
 * We enforce only one user at a time here with the open/close.
 */
static int rtc_open(struct inode *inode, struct file *file)
{
      if (!atomic_dec_and_test(&rtc_status)) {
            atomic_inc(&rtc_status);
            return -EBUSY;
      }
      return 0;
}

static int rtc_release(struct inode *inode, struct file *file)
{
      atomic_inc(&rtc_status);
      return 0;
}

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

static const struct file_operations rtc_fops = {
      .unlocked_ioctl   = rtc_ioctl,
      .open       = rtc_open,
      .release    = rtc_release,
      .llseek           = noop_llseek,
};

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

static int __init rtc_DP8570A_init(void)
{
      if (!MACH_IS_BVME6000)
            return -ENODEV;

      printk(KERN_INFO "DP8570A Real Time Clock Driver v%s\n", RTC_VERSION);
      return misc_register(&rtc_dev);
}
module_init(rtc_DP8570A_init);

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