/*
   * 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 interrupts 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/init.h>
  #include <linux/rtc.h>
  #include <linux/proc_fs.h>

  #include <linux/seq_file.h>

  #include <linux/efi.h>

  #include <linux/uaccess.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 long efi_rtc_ioctl(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
  ");
  		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 long efi_rtc_ioctl(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
  ");
  				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 -ENOTTY;

  }
  
  /*
   *	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,

  	.unlocked_ioctl	= efi_rtc_ioctl,

  	.open		= efi_rtc_open,
  	.release	= efi_rtc_close,

  	.llseek		= no_llseek,

  };

  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_proc_show(struct seq_file *m, void *v)

  {
  	efi_time_t 	eft, alm;
  	efi_time_cap_t	cap;

  	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);

  	seq_printf(m,
  		   "Time           : %u:%u:%u.%09u
  "
  		   "Date           : %u-%u-%u
  "
  		   "Daylight       : %u
  ",
  		   eft.hour, eft.minute, eft.second, eft.nanosecond, 
  		   eft.year, eft.month, eft.day,
  		   eft.daylight);

  
  	if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)

  		seq_puts(m, "Timezone       : unspecified
  ");

  	else
  		/* XXX fixme: convert to string? */

  		seq_printf(m, "Timezone       : %u
  ", eft.timezone);

  	seq_printf(m,
  		   "Alarm Time     : %u:%u:%u.%09u
  "
  		   "Alarm Date     : %u-%u-%u
  "
  		   "Alarm Daylight : %u
  "
  		   "Enabled        : %s
  "
  		   "Pending        : %s
  ",
  		   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)

  		seq_puts(m, "Timezone       : unspecified
  ");

  	else
  		/* XXX fixme: convert to string? */

  		seq_printf(m, "Timezone       : %u
  ", alm.timezone);

  
  	/*
  	 * now prints the capabilities
  	 */

  	seq_printf(m,
  		   "Resolution     : %u
  "
  		   "Accuracy       : %u
  "
  		   "SetstoZero     : %u
  ",
  		   cap.resolution, cap.accuracy, cap.sets_to_zero);

  	return 0;

  }

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

  {

  	return single_open(file, efi_rtc_proc_show, NULL);

  }

  static const struct file_operations efi_rtc_proc_fops = {
  	.open		= efi_rtc_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,

  	.release	= single_release,

  };

  static int __init 
  efi_rtc_init(void)
  {
  	int ret;
  	struct proc_dir_entry *dir;
  
  	printk(KERN_INFO "EFI Time Services Driver v%s
  ", EFI_RTC_VERSION);
  
  	ret = misc_register(&efi_rtc_dev);
  	if (ret) {
  		printk(KERN_ERR "efirtc: can't misc_register on minor=%d
  ",
  				EFI_RTC_MINOR);
  		return ret;
  	}

  	dir = proc_create("driver/efirtc", 0, NULL, &efi_rtc_proc_fops);

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

  device_initcall(efi_rtc_init);

  /*

  MODULE_LICENSE("GPL");

  */