linux/drivers/rtc/rtc-efi.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * rtc-efi: RTC Class Driver for EFI-based systems
   4 *
   5 * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   6 *
   7 * Author: dann frazier <dannf@dannf.org>
   8 * Based on efirtc.c by Stephane Eranian
   9 */
  10
  11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/stringify.h>
  16#include <linux/time.h>
  17#include <linux/platform_device.h>
  18#include <linux/rtc.h>
  19#include <linux/efi.h>
  20
  21#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  22
  23/*
  24 * returns day of the year [0-365]
  25 */
  26static inline int
  27compute_yday(efi_time_t *eft)
  28{
  29        /* efi_time_t.month is in the [1-12] so, we need -1 */
  30        return rtc_year_days(eft->day, eft->month - 1, eft->year);
  31}
  32
  33/*
  34 * returns day of the week [0-6] 0=Sunday
  35 */
  36static int
  37compute_wday(efi_time_t *eft, int yday)
  38{
  39        int ndays = eft->year * (365 % 7)
  40                    + (eft->year - 1) / 4
  41                    - (eft->year - 1) / 100
  42                    + (eft->year - 1) / 400
  43                    + yday;
  44
  45        /*
  46         * 1/1/0000 may or may not have been a Sunday (if it ever existed at
  47         * all) but assuming it was makes this calculation work correctly.
  48         */
  49        return ndays % 7;
  50}
  51
  52static void
  53convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
  54{
  55        eft->year       = wtime->tm_year + 1900;
  56        eft->month      = wtime->tm_mon + 1;
  57        eft->day        = wtime->tm_mday;
  58        eft->hour       = wtime->tm_hour;
  59        eft->minute     = wtime->tm_min;
  60        eft->second     = wtime->tm_sec;
  61        eft->nanosecond = 0;
  62        eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
  63        eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
  64}
  65
  66static bool
  67convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
  68{
  69        memset(wtime, 0, sizeof(*wtime));
  70
  71        if (eft->second >= 60)
  72                return false;
  73        wtime->tm_sec  = eft->second;
  74
  75        if (eft->minute >= 60)
  76                return false;
  77        wtime->tm_min  = eft->minute;
  78
  79        if (eft->hour >= 24)
  80                return false;
  81        wtime->tm_hour = eft->hour;
  82
  83        if (!eft->day || eft->day > 31)
  84                return false;
  85        wtime->tm_mday = eft->day;
  86
  87        if (!eft->month || eft->month > 12)
  88                return false;
  89        wtime->tm_mon  = eft->month - 1;
  90
  91        if (eft->year < 1900 || eft->year > 9999)
  92                return false;
  93        wtime->tm_year = eft->year - 1900;
  94
  95        /* day in the year [1-365]*/
  96        wtime->tm_yday = compute_yday(eft);
  97
  98        /* day of the week [0-6], Sunday=0 */
  99        wtime->tm_wday = compute_wday(eft, wtime->tm_yday);
 100
 101        switch (eft->daylight & EFI_ISDST) {
 102        case EFI_ISDST:
 103                wtime->tm_isdst = 1;
 104                break;
 105        case EFI_TIME_ADJUST_DAYLIGHT:
 106                wtime->tm_isdst = 0;
 107                break;
 108        default:
 109                wtime->tm_isdst = -1;
 110        }
 111
 112        return true;
 113}
 114
 115static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 116{
 117        efi_time_t eft;
 118        efi_status_t status;
 119
 120        /*
 121         * As of EFI v1.10, this call always returns an unsupported status
 122         */
 123        status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
 124                                     (efi_bool_t *)&wkalrm->pending, &eft);
 125
 126        if (status != EFI_SUCCESS)
 127                return -EINVAL;
 128
 129        if (!convert_from_efi_time(&eft, &wkalrm->time))
 130                return -EIO;
 131
 132        return rtc_valid_tm(&wkalrm->time);
 133}
 134
 135static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 136{
 137        efi_time_t eft;
 138        efi_status_t status;
 139
 140        convert_to_efi_time(&wkalrm->time, &eft);
 141
 142        /*
 143         * XXX Fixme:
 144         * As of EFI 0.92 with the firmware I have on my
 145         * machine this call does not seem to work quite
 146         * right
 147         *
 148         * As of v1.10, this call always returns an unsupported status
 149         */
 150        status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
 151
 152        dev_warn(dev, "write status is %d\n", (int)status);
 153
 154        return status == EFI_SUCCESS ? 0 : -EINVAL;
 155}
 156
 157static int efi_read_time(struct device *dev, struct rtc_time *tm)
 158{
 159        efi_status_t status;
 160        efi_time_t eft;
 161        efi_time_cap_t cap;
 162
 163        status = efi.get_time(&eft, &cap);
 164
 165        if (status != EFI_SUCCESS) {
 166                /* should never happen */
 167                dev_err(dev, "can't read time\n");
 168                return -EINVAL;
 169        }
 170
 171        if (!convert_from_efi_time(&eft, tm))
 172                return -EIO;
 173
 174        return 0;
 175}
 176
 177static int efi_set_time(struct device *dev, struct rtc_time *tm)
 178{
 179        efi_status_t status;
 180        efi_time_t eft;
 181
 182        convert_to_efi_time(tm, &eft);
 183
 184        status = efi.set_time(&eft);
 185
 186        return status == EFI_SUCCESS ? 0 : -EINVAL;
 187}
 188
 189static int efi_procfs(struct device *dev, struct seq_file *seq)
 190{
 191        efi_time_t      eft, alm;
 192        efi_time_cap_t  cap;
 193        efi_bool_t      enabled, pending;
 194
 195        memset(&eft, 0, sizeof(eft));
 196        memset(&alm, 0, sizeof(alm));
 197        memset(&cap, 0, sizeof(cap));
 198
 199        efi.get_time(&eft, &cap);
 200        efi.get_wakeup_time(&enabled, &pending, &alm);
 201
 202        seq_printf(seq,
 203                   "Time\t\t: %u:%u:%u.%09u\n"
 204                   "Date\t\t: %u-%u-%u\n"
 205                   "Daylight\t: %u\n",
 206                   eft.hour, eft.minute, eft.second, eft.nanosecond,
 207                   eft.year, eft.month, eft.day,
 208                   eft.daylight);
 209
 210        if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 211                seq_puts(seq, "Timezone\t: unspecified\n");
 212        else
 213                /* XXX fixme: convert to string? */
 214                seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
 215
 216        seq_printf(seq,
 217                   "Alarm Time\t: %u:%u:%u.%09u\n"
 218                   "Alarm Date\t: %u-%u-%u\n"
 219                   "Alarm Daylight\t: %u\n"
 220                   "Enabled\t\t: %s\n"
 221                   "Pending\t\t: %s\n",
 222                   alm.hour, alm.minute, alm.second, alm.nanosecond,
 223                   alm.year, alm.month, alm.day,
 224                   alm.daylight,
 225                   enabled == 1 ? "yes" : "no",
 226                   pending == 1 ? "yes" : "no");
 227
 228        if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 229                seq_puts(seq, "Timezone\t: unspecified\n");
 230        else
 231                /* XXX fixme: convert to string? */
 232                seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
 233
 234        /*
 235         * now prints the capabilities
 236         */
 237        seq_printf(seq,
 238                   "Resolution\t: %u\n"
 239                   "Accuracy\t: %u\n"
 240                   "SetstoZero\t: %u\n",
 241                   cap.resolution, cap.accuracy, cap.sets_to_zero);
 242
 243        return 0;
 244}
 245
 246static const struct rtc_class_ops efi_rtc_ops = {
 247        .read_time      = efi_read_time,
 248        .set_time       = efi_set_time,
 249        .read_alarm     = efi_read_alarm,
 250        .set_alarm      = efi_set_alarm,
 251        .proc           = efi_procfs,
 252};
 253
 254static int __init efi_rtc_probe(struct platform_device *dev)
 255{
 256        struct rtc_device *rtc;
 257        efi_time_t eft;
 258        efi_time_cap_t cap;
 259
 260        /* First check if the RTC is usable */
 261        if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
 262                return -ENODEV;
 263
 264        rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops,
 265                                        THIS_MODULE);
 266        if (IS_ERR(rtc))
 267                return PTR_ERR(rtc);
 268
 269        rtc->uie_unsupported = 1;
 270        platform_set_drvdata(dev, rtc);
 271
 272        return 0;
 273}
 274
 275static struct platform_driver efi_rtc_driver = {
 276        .driver = {
 277                .name = "rtc-efi",
 278        },
 279};
 280
 281module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
 282
 283MODULE_ALIAS("platform:rtc-efi");
 284MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
 285MODULE_LICENSE("GPL");
 286MODULE_DESCRIPTION("EFI RTC driver");
 287MODULE_ALIAS("platform:rtc-efi");
 288