drivers/rtc/rtc-efi.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * rtc-efi: RTC Class Driver for EFI-based systems
0004  *
0005  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
0006  *
0007  * Author: dann frazier <dannf@dannf.org>
0008  * Based on efirtc.c by Stephane Eranian
0009  */
0010
0011 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0012
0013 #include <linux/kernel.h>
0014 #include <linux/module.h>
0015 #include <linux/stringify.h>
0016 #include <linux/time.h>
0017 #include <linux/platform_device.h>
0018 #include <linux/rtc.h>
0019 #include <linux/efi.h>
0020
0021 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
0022
0023 /*
0024  * returns day of the year [0-365]
0025  */
0026 static inline int
0027 compute_yday(efi_time_t *eft)
0028 {
0029     /* efi_time_t.month is in the [1-12] so, we need -1 */
0030     return rtc_year_days(eft->day, eft->month - 1, eft->year);
0031 }
0032
0033 /*
0034  * returns day of the week [0-6] 0=Sunday
0035  */
0036 static int
0037 compute_wday(efi_time_t *eft, int yday)
0038 {
0039     int ndays = eft->year * (365 % 7)
0040             + (eft->year - 1) / 4
0041             - (eft->year - 1) / 100
0042             + (eft->year - 1) / 400
0043             + yday;
0044
0045     /*
0046      * 1/1/0000 may or may not have been a Sunday (if it ever existed at
0047      * all) but assuming it was makes this calculation work correctly.
0048      */
0049     return ndays % 7;
0050 }
0051
0052 static void
0053 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
0054 {
0055     eft->year   = wtime->tm_year + 1900;
0056     eft->month  = wtime->tm_mon + 1;
0057     eft->day    = wtime->tm_mday;
0058     eft->hour   = wtime->tm_hour;
0059     eft->minute = wtime->tm_min;
0060     eft->second = wtime->tm_sec;
0061     eft->nanosecond = 0;
0062     eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
0063     eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
0064 }
0065
0066 static bool
0067 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
0068 {
0069     memset(wtime, 0, sizeof(*wtime));
0070
0071     if (eft->second >= 60)
0072         return false;
0073     wtime->tm_sec  = eft->second;
0074
0075     if (eft->minute >= 60)
0076         return false;
0077     wtime->tm_min  = eft->minute;
0078
0079     if (eft->hour >= 24)
0080         return false;
0081     wtime->tm_hour = eft->hour;
0082
0083     if (!eft->day || eft->day > 31)
0084         return false;
0085     wtime->tm_mday = eft->day;
0086
0087     if (!eft->month || eft->month > 12)
0088         return false;
0089     wtime->tm_mon  = eft->month - 1;
0090
0091     if (eft->year < 1900 || eft->year > 9999)
0092         return false;
0093     wtime->tm_year = eft->year - 1900;
0094
0095     /* day in the year [1-365]*/
0096     wtime->tm_yday = compute_yday(eft);
0097
0098     /* day of the week [0-6], Sunday=0 */
0099     wtime->tm_wday = compute_wday(eft, wtime->tm_yday);
0100
0101     switch (eft->daylight & EFI_ISDST) {
0102     case EFI_ISDST:
0103         wtime->tm_isdst = 1;
0104         break;
0105     case EFI_TIME_ADJUST_DAYLIGHT:
0106         wtime->tm_isdst = 0;
0107         break;
0108     default:
0109         wtime->tm_isdst = -1;
0110     }
0111
0112     return true;
0113 }
0114
0115 static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
0116 {
0117     efi_time_t eft;
0118     efi_status_t status;
0119
0120     /*
0121      * As of EFI v1.10, this call always returns an unsupported status
0122      */
0123     status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
0124                      (efi_bool_t *)&wkalrm->pending, &eft);
0125
0126     if (status != EFI_SUCCESS)
0127         return -EINVAL;
0128
0129     if (!convert_from_efi_time(&eft, &wkalrm->time))
0130         return -EIO;
0131
0132     return rtc_valid_tm(&wkalrm->time);
0133 }
0134
0135 static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
0136 {
0137     efi_time_t eft;
0138     efi_status_t status;
0139
0140     convert_to_efi_time(&wkalrm->time, &eft);
0141
0142     /*
0143      * XXX Fixme:
0144      * As of EFI 0.92 with the firmware I have on my
0145      * machine this call does not seem to work quite
0146      * right
0147      *
0148      * As of v1.10, this call always returns an unsupported status
0149      */
0150     status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
0151
0152     dev_warn(dev, "write status is %d\n", (int)status);
0153
0154     return status == EFI_SUCCESS ? 0 : -EINVAL;
0155 }
0156
0157 static int efi_read_time(struct device *dev, struct rtc_time *tm)
0158 {
0159     efi_status_t status;
0160     efi_time_t eft;
0161     efi_time_cap_t cap;
0162
0163     status = efi.get_time(&eft, &cap);
0164
0165     if (status != EFI_SUCCESS) {
0166         /* should never happen */
0167         dev_err(dev, "can't read time\n");
0168         return -EINVAL;
0169     }
0170
0171     if (!convert_from_efi_time(&eft, tm))
0172         return -EIO;
0173
0174     return 0;
0175 }
0176
0177 static int efi_set_time(struct device *dev, struct rtc_time *tm)
0178 {
0179     efi_status_t status;
0180     efi_time_t eft;
0181
0182     convert_to_efi_time(tm, &eft);
0183
0184     status = efi.set_time(&eft);
0185
0186     return status == EFI_SUCCESS ? 0 : -EINVAL;
0187 }
0188
0189 static int efi_procfs(struct device *dev, struct seq_file *seq)
0190 {
0191     efi_time_t      eft, alm;
0192     efi_time_cap_t  cap;
0193     efi_bool_t      enabled, pending;
0194
0195     memset(&eft, 0, sizeof(eft));
0196     memset(&alm, 0, sizeof(alm));
0197     memset(&cap, 0, sizeof(cap));
0198
0199     efi.get_time(&eft, &cap);
0200     efi.get_wakeup_time(&enabled, &pending, &alm);
0201
0202     seq_printf(seq,
0203            "Time\t\t: %u:%u:%u.%09u\n"
0204            "Date\t\t: %u-%u-%u\n"
0205            "Daylight\t: %u\n",
0206            eft.hour, eft.minute, eft.second, eft.nanosecond,
0207            eft.year, eft.month, eft.day,
0208            eft.daylight);
0209
0210     if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
0211         seq_puts(seq, "Timezone\t: unspecified\n");
0212     else
0213         /* XXX fixme: convert to string? */
0214         seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
0215
0216     seq_printf(seq,
0217            "Alarm Time\t: %u:%u:%u.%09u\n"
0218            "Alarm Date\t: %u-%u-%u\n"
0219            "Alarm Daylight\t: %u\n"
0220            "Enabled\t\t: %s\n"
0221            "Pending\t\t: %s\n",
0222            alm.hour, alm.minute, alm.second, alm.nanosecond,
0223            alm.year, alm.month, alm.day,
0224            alm.daylight,
0225            enabled == 1 ? "yes" : "no",
0226            pending == 1 ? "yes" : "no");
0227
0228     if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
0229         seq_puts(seq, "Timezone\t: unspecified\n");
0230     else
0231         /* XXX fixme: convert to string? */
0232         seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
0233
0234     /*
0235      * now prints the capabilities
0236      */
0237     seq_printf(seq,
0238            "Resolution\t: %u\n"
0239            "Accuracy\t: %u\n"
0240            "SetstoZero\t: %u\n",
0241            cap.resolution, cap.accuracy, cap.sets_to_zero);
0242
0243     return 0;
0244 }
0245
0246 static const struct rtc_class_ops efi_rtc_ops = {
0247     .read_time  = efi_read_time,
0248     .set_time   = efi_set_time,
0249     .read_alarm = efi_read_alarm,
0250     .set_alarm  = efi_set_alarm,
0251     .proc       = efi_procfs,
0252 };
0253
0254 static int __init efi_rtc_probe(struct platform_device *dev)
0255 {
0256     struct rtc_device *rtc;
0257     efi_time_t eft;
0258     efi_time_cap_t cap;
0259
0260     /* First check if the RTC is usable */
0261     if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
0262         return -ENODEV;
0263
0264     rtc = devm_rtc_allocate_device(&dev->dev);
0265     if (IS_ERR(rtc))
0266         return PTR_ERR(rtc);
0267
0268     platform_set_drvdata(dev, rtc);
0269
0270     rtc->ops = &efi_rtc_ops;
0271     clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
0272     set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features);
0273
0274     return devm_rtc_register_device(rtc);
0275 }
0276
0277 static struct platform_driver efi_rtc_driver = {
0278     .driver = {
0279         .name = "rtc-efi",
0280     },
0281 };
0282
0283 module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
0284
0285 MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
0286 MODULE_LICENSE("GPL");
0287 MODULE_DESCRIPTION("EFI RTC driver");
0288 MODULE_ALIAS("platform:rtc-efi");