/*
   * rtc-efi: RTC Class Driver for EFI-based systems
   *
   * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   *

   * Author: dann frazier <dannf@dannf.org>

   * Based on efirtc.c by Stephane Eranian
   *
   *  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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/stringify.h>

  #include <linux/time.h>
  #include <linux/platform_device.h>
  #include <linux/rtc.h>
  #include <linux/efi.h>
  
  #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)

  
  /*
   * 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 rtc_year_days(eft->day, eft->month - 1, eft->year);

  }

  /*
   * returns day of the week [0-6] 0=Sunday

   */
  static int

  compute_wday(efi_time_t *eft, int yday)

  {

  	int ndays = eft->year * (365 % 7)
  		    + (eft->year - 1) / 4
  		    - (eft->year - 1) / 100
  		    + (eft->year - 1) / 400
  		    + yday;

  
  	/*

  	 * 1/1/0000 may or may not have been a Sunday (if it ever existed at
  	 * all) but assuming it was makes this calculation work correctly.

  	 */

  	return ndays % 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 bool

  convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
  {
  	memset(wtime, 0, sizeof(*wtime));

  
  	if (eft->second >= 60)
  		return false;

  	wtime->tm_sec  = eft->second;

  
  	if (eft->minute >= 60)
  		return false;

  	wtime->tm_min  = eft->minute;

  
  	if (eft->hour >= 24)
  		return false;

  	wtime->tm_hour = eft->hour;

  
  	if (!eft->day || eft->day > 31)
  		return false;

  	wtime->tm_mday = eft->day;

  
  	if (!eft->month || eft->month > 12)
  		return false;

  	wtime->tm_mon  = eft->month - 1;

  	if (eft->year < 1900 || eft->year > 9999)

  		return false;

  	wtime->tm_year = eft->year - 1900;

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

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

  
  	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;
  	}

  
  	return true;

  }
  
  static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
  {
  	efi_time_t eft;
  	efi_status_t status;
  
  	/*
  	 * As of EFI v1.10, this call always returns an unsupported status
  	 */
  	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
  				     (efi_bool_t *)&wkalrm->pending, &eft);
  
  	if (status != EFI_SUCCESS)
  		return -EINVAL;

  	if (!convert_from_efi_time(&eft, &wkalrm->time))
  		return -EIO;

  
  	return rtc_valid_tm(&wkalrm->time);
  }
  
  static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
  {
  	efi_time_t eft;
  	efi_status_t status;
  
  	convert_to_efi_time(&wkalrm->time, &eft);
  
  	/*
  	 * XXX Fixme:
  	 * As of EFI 0.92 with the firmware I have on my
  	 * machine this call does not seem to work quite
  	 * right
  	 *
  	 * As of v1.10, this call always returns an unsupported status
  	 */
  	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);

  	dev_warn(dev, "write status is %d
  ", (int)status);

  
  	return status == EFI_SUCCESS ? 0 : -EINVAL;
  }
  
  static int efi_read_time(struct device *dev, struct rtc_time *tm)
  {
  	efi_status_t status;
  	efi_time_t eft;
  	efi_time_cap_t cap;
  
  	status = efi.get_time(&eft, &cap);
  
  	if (status != EFI_SUCCESS) {
  		/* should never happen */

  		dev_err(dev, "can't read time
  ");

  		return -EINVAL;
  	}

  	if (!convert_from_efi_time(&eft, tm))
  		return -EIO;

  
  	return rtc_valid_tm(tm);
  }
  
  static int efi_set_time(struct device *dev, struct rtc_time *tm)
  {
  	efi_status_t status;
  	efi_time_t eft;
  
  	convert_to_efi_time(tm, &eft);
  
  	status = efi.set_time(&eft);
  
  	return status == EFI_SUCCESS ? 0 : -EINVAL;
  }

  static int efi_procfs(struct device *dev, struct seq_file *seq)
  {
  	efi_time_t      eft, alm;
  	efi_time_cap_t  cap;
  	efi_bool_t      enabled, pending;
  
  	memset(&eft, 0, sizeof(eft));
  	memset(&alm, 0, sizeof(alm));
  	memset(&cap, 0, sizeof(cap));
  
  	efi.get_time(&eft, &cap);
  	efi.get_wakeup_time(&enabled, &pending, &alm);
  
  	seq_printf(seq,
  		   "Time\t\t: %u:%u:%u.%09u
  "
  		   "Date\t\t: %u-%u-%u
  "
  		   "Daylight\t: %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(seq, "Timezone\t: unspecified
  ");
  	else
  		/* XXX fixme: convert to string? */
  		seq_printf(seq, "Timezone\t: %u
  ", eft.timezone);
  
  	seq_printf(seq,
  		   "Alarm Time\t: %u:%u:%u.%09u
  "
  		   "Alarm Date\t: %u-%u-%u
  "
  		   "Alarm Daylight\t: %u
  "
  		   "Enabled\t\t: %s
  "
  		   "Pending\t\t: %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(seq, "Timezone\t: unspecified
  ");
  	else
  		/* XXX fixme: convert to string? */
  		seq_printf(seq, "Timezone\t: %u
  ", alm.timezone);
  
  	/*
  	 * now prints the capabilities
  	 */
  	seq_printf(seq,
  		   "Resolution\t: %u
  "
  		   "Accuracy\t: %u
  "
  		   "SetstoZero\t: %u
  ",
  		   cap.resolution, cap.accuracy, cap.sets_to_zero);
  
  	return 0;
  }

  static const struct rtc_class_ops efi_rtc_ops = {

  	.read_time	= efi_read_time,
  	.set_time	= efi_set_time,
  	.read_alarm	= efi_read_alarm,
  	.set_alarm	= efi_set_alarm,
  	.proc		= efi_procfs,

  };
  
  static int __init efi_rtc_probe(struct platform_device *dev)
  {
  	struct rtc_device *rtc;

  	efi_time_t eft;
  	efi_time_cap_t cap;
  
  	/* First check if the RTC is usable */
  	if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
  		return -ENODEV;

  	rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops,

  					THIS_MODULE);
  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);

  	rtc->uie_unsupported = 1;

  	platform_set_drvdata(dev, rtc);
  
  	return 0;
  }

  static struct platform_driver efi_rtc_driver = {
  	.driver = {
  		.name = "rtc-efi",

  	},

  };

  module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);

  MODULE_ALIAS("platform:rtc-efi");

  MODULE_AUTHOR("dann frazier <dannf@dannf.org>");

  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("EFI RTC driver");

  MODULE_ALIAS("platform:rtc-efi");