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