drivers/rtc/rtc-efi.c

   1 /*
   2  * rtc-efi: RTC Class Driver for EFI-based systems
   3  *
   4  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   5  *
   6  * Author: dann frazier <dannf@hp.com>
   7  * Based on efirtc.c by Stephane Eranian
   8  *
   9  *  This program is free software; you can redistribute  it and/or modify it
  10  *  under  the terms of  the GNU General  Public License as published by the
  11  *  Free Software Foundation;  either version 2 of the  License, or (at your
  12  *  option) any later version.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/time.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/rtc.h>
  21 #include <linux/efi.h>
  22
  23 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  24 /*
  25  * EFI Epoch is 1/1/1998
  26  */
  27 #define EFI_RTC_EPOCH           1998
  28
  29 /*
  30  * returns day of the year [0-365]
  31  */
  32 static inline int
  33 compute_yday(efi_time_t *eft)
  34 {
  35         /* efi_time_t.month is in the [1-12] so, we need -1 */
  36         return rtc_year_days(eft->day - 1, eft->month - 1, eft->year);
  37 }
  38 /*
  39  * returns day of the week [0-6] 0=Sunday
  40  *
  41  * Don't try to provide a year that's before 1998, please !
  42  */
  43 static int
  44 compute_wday(efi_time_t *eft)
  45 {
  46         int y;
  47         int ndays = 0;
  48
  49         if (eft->year < 1998) {
  50                 printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
  51                 return -1;
  52         }
  53
  54         for (y = EFI_RTC_EPOCH; y < eft->year; y++)
  55                 ndays += 365 + (is_leap_year(y) ? 1 : 0);
  56
  57         ndays += compute_yday(eft);
  58
  59         /*
  60          * 4=1/1/1998 was a Thursday
  61          */
  62         return (ndays + 4) % 7;
  63 }
  64
  65 static void
  66 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
  67 {
  68         eft->year       = wtime->tm_year + 1900;
  69         eft->month      = wtime->tm_mon + 1;
  70         eft->day        = wtime->tm_mday;
  71         eft->hour       = wtime->tm_hour;
  72         eft->minute     = wtime->tm_min;
  73         eft->second     = wtime->tm_sec;
  74         eft->nanosecond = 0;
  75         eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
  76         eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
  77 }
  78
  79 static void
  80 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
  81 {
  82         memset(wtime, 0, sizeof(*wtime));
  83         wtime->tm_sec  = eft->second;
  84         wtime->tm_min  = eft->minute;
  85         wtime->tm_hour = eft->hour;
  86         wtime->tm_mday = eft->day;
  87         wtime->tm_mon  = eft->month - 1;
  88         wtime->tm_year = eft->year - 1900;
  89
  90         /* day of the week [0-6], Sunday=0 */
  91         wtime->tm_wday = compute_wday(eft);
  92
  93         /* day in the year [1-365]*/
  94         wtime->tm_yday = compute_yday(eft);
  95
  96
  97         switch (eft->daylight & EFI_ISDST) {
  98         case EFI_ISDST:
  99                 wtime->tm_isdst = 1;
 100                 break;
 101         case EFI_TIME_ADJUST_DAYLIGHT:
 102                 wtime->tm_isdst = 0;
 103                 break;
 104         default:
 105                 wtime->tm_isdst = -1;
 106         }
 107 }
 108
 109 static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 110 {
 111         efi_time_t eft;
 112         efi_status_t status;
 113
 114         /*
 115          * As of EFI v1.10, this call always returns an unsupported status
 116          */
 117         status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
 118                                      (efi_bool_t *)&wkalrm->pending, &eft);
 119
 120         if (status != EFI_SUCCESS)
 121                 return -EINVAL;
 122
 123         convert_from_efi_time(&eft, &wkalrm->time);
 124
 125         return rtc_valid_tm(&wkalrm->time);
 126 }
 127
 128 static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 129 {
 130         efi_time_t eft;
 131         efi_status_t status;
 132
 133         convert_to_efi_time(&wkalrm->time, &eft);
 134
 135         /*
 136          * XXX Fixme:
 137          * As of EFI 0.92 with the firmware I have on my
 138          * machine this call does not seem to work quite
 139          * right
 140          *
 141          * As of v1.10, this call always returns an unsupported status
 142          */
 143         status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
 144
 145         printk(KERN_WARNING "write status is %d\n", (int)status);
 146
 147         return status == EFI_SUCCESS ? 0 : -EINVAL;
 148 }
 149
 150 static int efi_read_time(struct device *dev, struct rtc_time *tm)
 151 {
 152         efi_status_t status;
 153         efi_time_t eft;
 154         efi_time_cap_t cap;
 155
 156         status = efi.get_time(&eft, &cap);
 157
 158         if (status != EFI_SUCCESS) {
 159                 /* should never happen */
 160                 printk(KERN_ERR "efitime: can't read time\n");
 161                 return -EINVAL;
 162         }
 163
 164         convert_from_efi_time(&eft, tm);
 165
 166         return rtc_valid_tm(tm);
 167 }
 168
 169 static int efi_set_time(struct device *dev, struct rtc_time *tm)
 170 {
 171         efi_status_t status;
 172         efi_time_t eft;
 173
 174         convert_to_efi_time(tm, &eft);
 175
 176         status = efi.set_time(&eft);
 177
 178         return status == EFI_SUCCESS ? 0 : -EINVAL;
 179 }
 180
 181 static const struct rtc_class_ops efi_rtc_ops = {
 182         .read_time = efi_read_time,
 183         .set_time = efi_set_time,
 184         .read_alarm = efi_read_alarm,
 185         .set_alarm = efi_set_alarm,
 186 };
 187
 188 static int __init efi_rtc_probe(struct platform_device *dev)
 189 {
 190         struct rtc_device *rtc;
 191
 192         rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
 193                                         THIS_MODULE);
 194         if (IS_ERR(rtc))
 195                 return PTR_ERR(rtc);
 196
 197         platform_set_drvdata(dev, rtc);
 198
 199         return 0;
 200 }
 201
 202 static int __exit efi_rtc_remove(struct platform_device *dev)
 203 {
 204         struct rtc_device *rtc = platform_get_drvdata(dev);
 205
 206         rtc_device_unregister(rtc);
 207
 208         return 0;
 209 }
 210
 211 static struct platform_driver efi_rtc_driver = {
 212         .driver = {
 213                 .name = "rtc-efi",
 214                 .owner = THIS_MODULE,
 215         },
 216         .remove = __exit_p(efi_rtc_remove),
 217 };
 218
 219 static int __init efi_rtc_init(void)
 220 {
 221         return platform_driver_probe(&efi_rtc_driver, efi_rtc_probe);
 222 }
 223
 224 static void __exit efi_rtc_exit(void)
 225 {
 226         platform_driver_unregister(&efi_rtc_driver);
 227 }
 228
 229 module_init(efi_rtc_init);
 230 module_exit(efi_rtc_exit);
 231
 232 MODULE_AUTHOR("dann frazier <dannf@hp.com>");
 233 MODULE_LICENSE("GPL");
 234 MODULE_DESCRIPTION("EFI RTC driver");