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#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/time.h>
  19#include <linux/platform_device.h>
  20#include <linux/rtc.h>
  21#include <linux/efi.h>
  22
  23#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  24/*
  25 * EFI Epoch is 1/1/1998
  26 */
  27#define EFI_RTC_EPOCH           1998
  28
  29/*
  30 * returns day of the year [0-365]
  31 */
  32static inline int
  33compute_yday(efi_time_t *eft)
  34{
  35        /* efi_time_t.month is in the [1-12] so, we need -1 */
  36        return rtc_year_days(eft->day - 1, eft->month - 1, eft->year);
  37}
  38/*
  39 * returns day of the week [0-6] 0=Sunday
  40 *
  41 * Don't try to provide a year that's before 1998, please !
  42 */
  43static int
  44compute_wday(efi_time_t *eft)
  45{
  46        int y;
  47        int ndays = 0;
  48
  49        if (eft->year < 1998) {
  50                printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
  51                return -1;
  52        }
  53
  54        for (y = EFI_RTC_EPOCH; y < eft->year; y++)
  55                ndays += 365 + (is_leap_year(y) ? 1 : 0);
  56
  57        ndays += compute_yday(eft);
  58
  59        /*
  60         * 4=1/1/1998 was a Thursday
  61         */
  62        return (ndays + 4) % 7;
  63}
  64
  65static void
  66convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
  67{
  68        eft->year       = wtime->tm_year + 1900;
  69        eft->month      = wtime->tm_mon + 1;
  70        eft->day        = wtime->tm_mday;
  71        eft->hour       = wtime->tm_hour;
  72        eft->minute     = wtime->tm_min;
  73        eft->second     = wtime->tm_sec;
  74        eft->nanosecond = 0;
  75        eft->daylight   = wtime->tm_isdst ? EFI_ISDST : 0;
  76        eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
  77}
  78
  79static void
  80convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
  81{
  82        memset(wtime, 0, sizeof(*wtime));
  83        wtime->tm_sec  = eft->second;
  84        wtime->tm_min  = eft->minute;
  85        wtime->tm_hour = eft->hour;
  86        wtime->tm_mday = eft->day;
  87        wtime->tm_mon  = eft->month - 1;
  88        wtime->tm_year = eft->year - 1900;
  89
  90        /* day of the week [0-6], Sunday=0 */
  91        wtime->tm_wday = compute_wday(eft);
  92
  93        /* day in the year [1-365]*/
  94        wtime->tm_yday = compute_yday(eft);
  95
  96
  97        switch (eft->daylight & EFI_ISDST) {
  98        case EFI_ISDST:
  99                wtime->tm_isdst = 1;
 100                break;
 101        case EFI_TIME_ADJUST_DAYLIGHT:
 102                wtime->tm_isdst = 0;
 103                break;
 104        default:
 105                wtime->tm_isdst = -1;
 106        }
 107}
 108
 109static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 110{
 111        efi_time_t eft;
 112        efi_status_t status;
 113
 114        /*
 115         * As of EFI v1.10, this call always returns an unsupported status
 116         */
 117        status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
 118                                     (efi_bool_t *)&wkalrm->pending, &eft);
 119
 120        if (status != EFI_SUCCESS)
 121                return -EINVAL;
 122
 123        convert_from_efi_time(&eft, &wkalrm->time);
 124
 125        return rtc_valid_tm(&wkalrm->time);
 126}
 127
 128static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 129{
 130        efi_time_t eft;
 131        efi_status_t status;
 132
 133        convert_to_efi_time(&wkalrm->time, &eft);
 134
 135        /*
 136         * XXX Fixme:
 137         * As of EFI 0.92 with the firmware I have on my
 138         * machine this call does not seem to work quite
 139         * right
 140         *
 141         * As of v1.10, this call always returns an unsupported status
 142         */
 143        status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
 144
 145        printk(KERN_WARNING "write status is %d\n", (int)status);
 146
 147        return status == EFI_SUCCESS ? 0 : -EINVAL;
 148}
 149
 150static int efi_read_time(struct device *dev, struct rtc_time *tm)
 151{
 152        efi_status_t status;
 153        efi_time_t eft;
 154        efi_time_cap_t cap;
 155
 156        status = efi.get_time(&eft, &cap);
 157
 158        if (status != EFI_SUCCESS) {
 159                /* should never happen */
 160                printk(KERN_ERR "efitime: can't read time\n");
 161                return -EINVAL;
 162        }
 163
 164        convert_from_efi_time(&eft, tm);
 165
 166        return rtc_valid_tm(tm);
 167}
 168
 169static int efi_set_time(struct device *dev, struct rtc_time *tm)
 170{
 171        efi_status_t status;
 172        efi_time_t eft;
 173
 174        convert_to_efi_time(tm, &eft);
 175
 176        status = efi.set_time(&eft);
 177
 178        return status == EFI_SUCCESS ? 0 : -EINVAL;
 179}
 180
 181static const struct rtc_class_ops efi_rtc_ops = {
 182        .read_time = efi_read_time,
 183        .set_time = efi_set_time,
 184        .read_alarm = efi_read_alarm,
 185        .set_alarm = efi_set_alarm,
 186};
 187
 188static int __init efi_rtc_probe(struct platform_device *dev)
 189{
 190        struct rtc_device *rtc;
 191
 192        rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
 193                                        THIS_MODULE);
 194        if (IS_ERR(rtc))
 195                return PTR_ERR(rtc);
 196
 197        platform_set_drvdata(dev, rtc);
 198
 199        return 0;
 200}
 201
 202static int __exit efi_rtc_remove(struct platform_device *dev)
 203{
 204        struct rtc_device *rtc = platform_get_drvdata(dev);
 205
 206        rtc_device_unregister(rtc);
 207
 208        return 0;
 209}
 210
 211static struct platform_driver efi_rtc_driver = {
 212        .driver = {
 213                .name = "rtc-efi",
 214                .owner = THIS_MODULE,
 215        },
 216        .remove = __exit_p(efi_rtc_remove),
 217};
 218
 219static int __init efi_rtc_init(void)
 220{
 221        return platform_driver_probe(&efi_rtc_driver, efi_rtc_probe);
 222}
 223
 224static void __exit efi_rtc_exit(void)
 225{
 226        platform_driver_unregister(&efi_rtc_driver);
 227}
 228
 229module_init(efi_rtc_init);
 230module_exit(efi_rtc_exit);
 231
 232MODULE_AUTHOR("dann frazier <dannf@hp.com>");
 233MODULE_LICENSE("GPL");
 234MODULE_DESCRIPTION("EFI RTC driver");
 235
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