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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@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");
229 

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