linux/drivers/rtc/rtc-efi.c
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   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 */
  34static inline int
  35compute_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 */
  45static int
  46compute_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
  67static void
  68convert_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
  81static void
  82convert_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
 111static 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
 130static 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
 152static 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
 171static 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
 183static 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
 190static int __init efi_rtc_probe(struct platform_device *dev)
 191{
 192        struct rtc_device *rtc;
 193
 194        rtc = rtc_device_register("rtc-efi", &dev->dev, &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
 204static int __exit efi_rtc_remove(struct platform_device *dev)
 205{
 206        struct rtc_device *rtc = platform_get_drvdata(dev);
 207
 208        rtc_device_unregister(rtc);
 209
 210        return 0;
 211}
 212
 213static struct platform_driver efi_rtc_driver = {
 214        .driver = {
 215                .name = "rtc-efi",
 216                .owner = THIS_MODULE,
 217        },
 218        .remove = __exit_p(efi_rtc_remove),
 219};
 220
 221static int __init efi_rtc_init(void)
 222{
 223        return platform_driver_probe(&efi_rtc_driver, efi_rtc_probe);
 224}
 225
 226static void __exit efi_rtc_exit(void)
 227{
 228        platform_driver_unregister(&efi_rtc_driver);
 229}
 230
 231module_init(efi_rtc_init);
 232module_exit(efi_rtc_exit);
 233
 234MODULE_AUTHOR("dann frazier <dannf@hp.com>");
 235MODULE_LICENSE("GPL");
 236MODULE_DESCRIPTION("EFI RTC driver");
 237
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