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@dannf.org>
   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 /*
  29  * returns day of the year [0-365]
  30  */
  31 static inline int
  32 compute_yday(efi_time_t *eft)
  33 {
  34         /* efi_time_t.month is in the [1-12] so, we need -1 */
  35         return rtc_year_days(eft->day, eft->month - 1, eft->year);
  36 }
  37
  38 /*
  39  * returns day of the week [0-6] 0=Sunday
  40  */
  41 static int
  42 compute_wday(efi_time_t *eft, int yday)
  43 {
  44         int ndays = eft->year * (365 % 7)
  45                     + (eft->year - 1) / 4
  46                     - (eft->year - 1) / 100
  47                     + (eft->year - 1) / 400
  48                     + yday;
  49
  50         /*
  51          * 1/1/0000 may or may not have been a Sunday (if it ever existed at
  52          * all) but assuming it was makes this calculation work correctly.
  53          */
  54         return ndays % 7;
  55 }
  56
  57 static void
  58 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
  59 {
  60         eft->year       = wtime->tm_year + 1900;
  61         eft->month      = wtime->tm_mon + 1;
  62         eft->day        = wtime->tm_mday;
  63         eft->hour       = wtime->tm_hour;
  64         eft->minute     = wtime->tm_min;
  65         eft->second     = wtime->tm_sec;
  66         eft->nanosecond = 0;
  67         eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
  68         eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
  69 }
  70
  71 static bool
  72 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
  73 {
  74         memset(wtime, 0, sizeof(*wtime));
  75
  76         if (eft->second >= 60)
  77                 return false;
  78         wtime->tm_sec  = eft->second;
  79
  80         if (eft->minute >= 60)
  81                 return false;
  82         wtime->tm_min  = eft->minute;
  83
  84         if (eft->hour >= 24)
  85                 return false;
  86         wtime->tm_hour = eft->hour;
  87
  88         if (!eft->day || eft->day > 31)
  89                 return false;
  90         wtime->tm_mday = eft->day;
  91
  92         if (!eft->month || eft->month > 12)
  93                 return false;
  94         wtime->tm_mon  = eft->month - 1;
  95
  96         if (eft->year < 1900 || eft->year > 9999)
  97                 return false;
  98         wtime->tm_year = eft->year - 1900;
  99
 100         /* day in the year [1-365]*/
 101         wtime->tm_yday = compute_yday(eft);
 102
 103         /* day of the week [0-6], Sunday=0 */
 104         wtime->tm_wday = compute_wday(eft, wtime->tm_yday);
 105
 106         switch (eft->daylight & EFI_ISDST) {
 107         case EFI_ISDST:
 108                 wtime->tm_isdst = 1;
 109                 break;
 110         case EFI_TIME_ADJUST_DAYLIGHT:
 111                 wtime->tm_isdst = 0;
 112                 break;
 113         default:
 114                 wtime->tm_isdst = -1;
 115         }
 116
 117         return true;
 118 }
 119
 120 static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 121 {
 122         efi_time_t eft;
 123         efi_status_t status;
 124
 125         /*
 126          * As of EFI v1.10, this call always returns an unsupported status
 127          */
 128         status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
 129                                      (efi_bool_t *)&wkalrm->pending, &eft);
 130
 131         if (status != EFI_SUCCESS)
 132                 return -EINVAL;
 133
 134         if (!convert_from_efi_time(&eft, &wkalrm->time))
 135                 return -EIO;
 136
 137         return rtc_valid_tm(&wkalrm->time);
 138 }
 139
 140 static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 141 {
 142         efi_time_t eft;
 143         efi_status_t status;
 144
 145         convert_to_efi_time(&wkalrm->time, &eft);
 146
 147         /*
 148          * XXX Fixme:
 149          * As of EFI 0.92 with the firmware I have on my
 150          * machine this call does not seem to work quite
 151          * right
 152          *
 153          * As of v1.10, this call always returns an unsupported status
 154          */
 155         status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
 156
 157         dev_warn(dev, "write status is %d\n", (int)status);
 158
 159         return status == EFI_SUCCESS ? 0 : -EINVAL;
 160 }
 161
 162 static int efi_read_time(struct device *dev, struct rtc_time *tm)
 163 {
 164         efi_status_t status;
 165         efi_time_t eft;
 166         efi_time_cap_t cap;
 167
 168         status = efi.get_time(&eft, &cap);
 169
 170         if (status != EFI_SUCCESS) {
 171                 /* should never happen */
 172                 dev_err(dev, "can't read time\n");
 173                 return -EINVAL;
 174         }
 175
 176         if (!convert_from_efi_time(&eft, tm))
 177                 return -EIO;
 178
 179         return rtc_valid_tm(tm);
 180 }
 181
 182 static int efi_set_time(struct device *dev, struct rtc_time *tm)
 183 {
 184         efi_status_t status;
 185         efi_time_t eft;
 186
 187         convert_to_efi_time(tm, &eft);
 188
 189         status = efi.set_time(&eft);
 190
 191         return status == EFI_SUCCESS ? 0 : -EINVAL;
 192 }
 193
 194 static const struct rtc_class_ops efi_rtc_ops = {
 195         .read_time = efi_read_time,
 196         .set_time = efi_set_time,
 197         .read_alarm = efi_read_alarm,
 198         .set_alarm = efi_set_alarm,
 199 };
 200
 201 static int __init efi_rtc_probe(struct platform_device *dev)
 202 {
 203         struct rtc_device *rtc;
 204
 205         rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops,
 206                                         THIS_MODULE);
 207         if (IS_ERR(rtc))
 208                 return PTR_ERR(rtc);
 209
 210         rtc->uie_unsupported = 1;
 211         platform_set_drvdata(dev, rtc);
 212
 213         return 0;
 214 }
 215
 216 static struct platform_driver efi_rtc_driver = {
 217         .driver = {
 218                 .name = "rtc-efi",
 219         },
 220 };
 221
 222 module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
 223
 224 MODULE_ALIAS("platform:rtc-efi");
 225 MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
 226 MODULE_LICENSE("GPL");
 227 MODULE_DESCRIPTION("EFI RTC driver");
 228 MODULE_ALIAS("platform:rtc-efi");