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efirtc.c

/*
 * EFI Time Services Driver for Linux
 *
 * Copyright (C) 1999 Hewlett-Packard Co
 * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
 *
 * Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
 *
 * This code provides an architected & portable interface to the real time
 * clock by using EFI instead of direct bit fiddling. The functionalities are 
 * quite different from the rtc.c driver. The only way to talk to the device 
 * is by using ioctl(). There is a /proc interface which provides the raw 
 * information.
 *
 * Please note that we have kept the API as close as possible to the
 * legacy RTC. The standard /sbin/hwclock program should work normally 
 * when used to get/set the time.
 *
 * NOTES:
 *    - Locking is required for safe execution of EFI calls with regards
 *      to interrrupts and SMP.
 *
 * TODO (December 1999):
 *    - provide the API to set/get the WakeUp Alarm (different from the
 *      rtc.c alarm).
 *    - SMP testing
 *    - Add module support
 */


#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/proc_fs.h>
#include <linux/efi.h>

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

#define EFI_RTC_VERSION       "0.4"

#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
/*
 * EFI Epoch is 1/1/1998
 */
#define EFI_RTC_EPOCH         1998

static DEFINE_SPINLOCK(efi_rtc_lock);

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

#define is_leap(year) \
          ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))

static const unsigned short int __mon_yday[2][13] =
{
      /* Normal years.  */
      { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
      /* Leap years.  */  
      { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};

/*
 * returns day of the year [0-365]
 */
static inline int
compute_yday(efi_time_t *eft)
{
      /* efi_time_t.month is in the [1-12] so, we need -1 */
      return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
}
/*
 * returns day of the week [0-6] 0=Sunday
 *
 * Don't try to provide a year that's before 1998, please !
 */
static int
compute_wday(efi_time_t *eft)
{
      int y;
      int ndays = 0;

      if ( eft->year < 1998 ) {
            printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
            return -1;
      }

      for(y=EFI_RTC_EPOCH; y < eft->year; y++ ) {
            ndays += 365 + (is_leap(y) ? 1 : 0);
      }
      ndays += compute_yday(eft);

      /*
       * 4=1/1/1998 was a Thursday
       */
      return (ndays + 4) % 7;
}

static void
convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
{

      eft->year   = wtime->tm_year + 1900;
      eft->month  = wtime->tm_mon + 1; 
      eft->day    = wtime->tm_mday;
      eft->hour   = wtime->tm_hour;
      eft->minute = wtime->tm_min;
      eft->second       = wtime->tm_sec;
      eft->nanosecond = 0; 
      eft->daylight     = wtime->tm_isdst ? EFI_ISDST: 0;
      eft->timezone     = EFI_UNSPECIFIED_TIMEZONE;
}

static void
convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
{
      memset(wtime, 0, sizeof(*wtime));
      wtime->tm_sec  = eft->second;
      wtime->tm_min  = eft->minute;
      wtime->tm_hour = eft->hour;
      wtime->tm_mday = eft->day;
      wtime->tm_mon  = eft->month - 1;
      wtime->tm_year = eft->year - 1900;

      /* day of the week [0-6], Sunday=0 */
      wtime->tm_wday = compute_wday(eft);

      /* day in the year [1-365]*/
      wtime->tm_yday = compute_yday(eft);


      switch (eft->daylight & EFI_ISDST) {
            case EFI_ISDST:
                  wtime->tm_isdst = 1;
                  break;
            case EFI_TIME_ADJUST_DAYLIGHT:
                  wtime->tm_isdst = 0;
                  break;
            default:
                  wtime->tm_isdst = -1;
      }
}

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

      efi_status_t      status;
      unsigned long     flags;
      efi_time_t  eft;
      efi_time_cap_t    cap;
      struct rtc_time   wtime;
      struct rtc_wkalrm __user *ewp;
      unsigned char     enabled, pending;

      switch (cmd) {
            case RTC_UIE_ON:
            case RTC_UIE_OFF:
            case RTC_PIE_ON:
            case RTC_PIE_OFF:
            case RTC_AIE_ON:
            case RTC_AIE_OFF:
            case RTC_ALM_SET:
            case RTC_ALM_READ:
            case RTC_IRQP_READ:
            case RTC_IRQP_SET:
            case RTC_EPOCH_READ:
            case RTC_EPOCH_SET:
                  return -EINVAL;

            case RTC_RD_TIME:

                  spin_lock_irqsave(&efi_rtc_lock, flags);

                  status = efi.get_time(&eft, &cap);

                  spin_unlock_irqrestore(&efi_rtc_lock,flags);

                  if (status != EFI_SUCCESS) {
                        /* should never happen */
                        printk(KERN_ERR "efitime: can't read time\n");
                        return -EINVAL;
                  }

                  convert_from_efi_time(&eft, &wtime);

                  return copy_to_user((void __user *)arg, &wtime,
                                  sizeof (struct rtc_time)) ? - EFAULT : 0;

            case RTC_SET_TIME:

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

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

                  convert_to_efi_time(&wtime, &eft);

                  spin_lock_irqsave(&efi_rtc_lock, flags);

                  status = efi.set_time(&eft);

                  spin_unlock_irqrestore(&efi_rtc_lock,flags);

                  return status == EFI_SUCCESS ? 0 : -EINVAL;

            case RTC_WKALM_SET:

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

                  ewp = (struct rtc_wkalrm __user *)arg;

                  if (  get_user(enabled, &ewp->enabled)
                     || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
                        return -EFAULT;

                  convert_to_efi_time(&wtime, &eft);

                  spin_lock_irqsave(&efi_rtc_lock, flags);
                  /*
                   * XXX Fixme:
                   * As of EFI 0.92 with the firmware I have on my
                   * machine this call does not seem to work quite
                   * right
                   */
                  status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);

                  spin_unlock_irqrestore(&efi_rtc_lock,flags);

                  return status == EFI_SUCCESS ? 0 : -EINVAL;

            case RTC_WKALM_RD:

                  spin_lock_irqsave(&efi_rtc_lock, flags);

                  status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);

                  spin_unlock_irqrestore(&efi_rtc_lock,flags);

                  if (status != EFI_SUCCESS) return -EINVAL;

                  ewp = (struct rtc_wkalrm __user *)arg;

                  if (  put_user(enabled, &ewp->enabled)
                     || put_user(pending, &ewp->pending)) return -EFAULT;

                  convert_from_efi_time(&eft, &wtime);

                  return copy_to_user(&ewp->time, &wtime,
                                  sizeof(struct rtc_time)) ? -EFAULT : 0;
      }
      return -EINVAL;
}

/*
 *    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
efi_rtc_open(struct inode *inode, struct file *file)
{
      /*
       * nothing special to do here
       * We do accept multiple open files at the same time as we
       * synchronize on the per call operation.
       */
      return 0;
}

static int
efi_rtc_close(struct inode *inode, struct file *file)
{
      return 0;
}

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

static const struct file_operations efi_rtc_fops = {
      .owner            = THIS_MODULE,
      .ioctl            = efi_rtc_ioctl,
      .open       = efi_rtc_open,
      .release    = efi_rtc_close,
};

static struct miscdevice efi_rtc_dev=
{
      EFI_RTC_MINOR,
      "efirtc",
      &efi_rtc_fops
};

/*
 *    We export RAW EFI information to /proc/driver/efirtc
 */
static int
efi_rtc_get_status(char *buf)
{
      efi_time_t  eft, alm;
      efi_time_cap_t    cap;
      char        *p = buf;
      efi_bool_t  enabled, pending; 
      unsigned long     flags;

      memset(&eft, 0, sizeof(eft));
      memset(&alm, 0, sizeof(alm));
      memset(&cap, 0, sizeof(cap));

      spin_lock_irqsave(&efi_rtc_lock, flags);

      efi.get_time(&eft, &cap);
      efi.get_wakeup_time(&enabled, &pending, &alm);

      spin_unlock_irqrestore(&efi_rtc_lock,flags);

      p += sprintf(p,
                 "Time           : %u:%u:%u.%09u\n"
                 "Date           : %u-%u-%u\n"
                 "Daylight       : %u\n",
                 eft.hour, eft.minute, eft.second, eft.nanosecond, 
                 eft.year, eft.month, eft.day,
                 eft.daylight);

      if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
            p += sprintf(p, "Timezone       : unspecified\n");
      else
            /* XXX fixme: convert to string? */
            p += sprintf(p, "Timezone       : %u\n", eft.timezone);
            

      p += sprintf(p,
                 "Alarm Time     : %u:%u:%u.%09u\n"
                 "Alarm Date     : %u-%u-%u\n"
                 "Alarm Daylight : %u\n"
                 "Enabled        : %s\n"
                 "Pending        : %s\n",
                 alm.hour, alm.minute, alm.second, alm.nanosecond, 
                 alm.year, alm.month, alm.day, 
                 alm.daylight,
                 enabled == 1 ? "yes" : "no",
                 pending == 1 ? "yes" : "no");

      if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
            p += sprintf(p, "Timezone       : unspecified\n");
      else
            /* XXX fixme: convert to string? */
            p += sprintf(p, "Timezone       : %u\n", alm.timezone);

      /*
       * now prints the capabilities
       */
      p += sprintf(p,
                 "Resolution     : %u\n"
                 "Accuracy       : %u\n"
                 "SetstoZero     : %u\n",
                  cap.resolution, cap.accuracy, cap.sets_to_zero);

      return  p - buf;
}

static int
efi_rtc_read_proc(char *page, char **start, off_t off,
                                 int count, int *eof, void *data)
{
        int len = efi_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 int __init 
efi_rtc_init(void)
{
      int ret;
      struct proc_dir_entry *dir;

      printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);

      ret = misc_register(&efi_rtc_dev);
      if (ret) {
            printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
                        EFI_RTC_MINOR);
            return ret;
      }

      dir = create_proc_read_entry ("driver/efirtc", 0, NULL,
                                efi_rtc_read_proc, NULL);
      if (dir == NULL) {
            printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
            misc_deregister(&efi_rtc_dev);
            return -1;
      }
      return 0;
}

static void __exit
efi_rtc_exit(void)
{
      /* not yet used */
}

module_init(efi_rtc_init);
module_exit(efi_rtc_exit);

MODULE_LICENSE("GPL");

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