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