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