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"); 216