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Linux/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         platform_set_drvdata(dev, rtc);
222 
223         return 0;
224 }
225 
226 static struct platform_driver efi_rtc_driver = {
227         .driver = {
228                 .name = "rtc-efi",
229                 .owner = THIS_MODULE,
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");
240 

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