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