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/*
* rtc-efi: RTC Class Driver for EFI-based systems
*
* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
*
* Author: dann frazier <dannf@hp.com>
* Based on efirtc.c by Stephane Eranian
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/time.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/efi.h>
#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
/*
* EFI Epoch is 1/1/1998
*/
#define EFI_RTC_EPOCH 1998
/*
* returns day of the year [0-365]
*/
static inline int
compute_yday(efi_time_t *eft)
{
/* efi_time_t.month is in the [1-12] so, we need -1 */
return rtc_year_days(eft->day, eft->month - 1, eft->year);
}
/*
* returns day of the week [0-6] 0=Sunday
*
* Don't try to provide a year that's before 1998, please !
*/
static int
compute_wday(efi_time_t *eft)
{
int y;
int ndays = 0;
if (eft->year < EFI_RTC_EPOCH) {
pr_err("EFI year < " __stringify(EFI_RTC_EPOCH) ", invalid date\n");
return -1;
}
for (y = EFI_RTC_EPOCH; y < eft->year; y++)
ndays += 365 + (is_leap_year(y) ? 1 : 0);
ndays += compute_yday(eft);
/*
* 4=1/1/1998 was a Thursday
*/
return (ndays + 4) % 7;
}
static void
convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
{
eft->year = wtime->tm_year + 1900;
eft->month = wtime->tm_mon + 1;
eft->day = wtime->tm_mday;
eft->hour = wtime->tm_hour;
eft->minute = wtime->tm_min;
eft->second = wtime->tm_sec;
eft->nanosecond = 0;
eft->daylight = wtime->tm_isdst ? EFI_ISDST : 0;
eft->timezone = EFI_UNSPECIFIED_TIMEZONE;
}
static bool
convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
{
memset(wtime, 0, sizeof(*wtime));
if (eft->second >= 60)
return false;
wtime->tm_sec = eft->second;
if (eft->minute >= 60)
return false;
wtime->tm_min = eft->minute;
if (eft->hour >= 24)
return false;
wtime->tm_hour = eft->hour;
if (!eft->day || eft->day > 31)
return false;
wtime->tm_mday = eft->day;
if (!eft->month || eft->month > 12)
return false;
wtime->tm_mon = eft->month - 1;
wtime->tm_year = eft->year - 1900;
/* day of the week [0-6], Sunday=0 */
wtime->tm_wday = compute_wday(eft);
if (wtime->tm_wday < 0)
return false;
/* day in the year [1-365]*/
wtime->tm_yday = compute_yday(eft);
switch (eft->daylight & EFI_ISDST) {
case EFI_ISDST:
wtime->tm_isdst = 1;
break;
case EFI_TIME_ADJUST_DAYLIGHT:
wtime->tm_isdst = 0;
break;
default:
wtime->tm_isdst = -1;
}
return true;
}
static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
efi_time_t eft;
efi_status_t status;
/*
* As of EFI v1.10, this call always returns an unsupported status
*/
status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
(efi_bool_t *)&wkalrm->pending, &eft);
if (status != EFI_SUCCESS)
return -EINVAL;
if (!convert_from_efi_time(&eft, &wkalrm->time))
return -EIO;
return rtc_valid_tm(&wkalrm->time);
}
static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
efi_time_t eft;
efi_status_t status;
convert_to_efi_time(&wkalrm->time, &eft);
/*
* XXX Fixme:
* As of EFI 0.92 with the firmware I have on my
* machine this call does not seem to work quite
* right
*
* As of v1.10, this call always returns an unsupported status
*/
status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
dev_warn(dev, "write status is %d\n", (int)status);
return status == EFI_SUCCESS ? 0 : -EINVAL;
}
static int efi_read_time(struct device *dev, struct rtc_time *tm)
{
efi_status_t status;
efi_time_t eft;
efi_time_cap_t cap;
status = efi.get_time(&eft, &cap);
if (status != EFI_SUCCESS) {
/* should never happen */
dev_err(dev, "can't read time\n");
return -EINVAL;
}
if (!convert_from_efi_time(&eft, tm))
return -EIO;
return rtc_valid_tm(tm);
}
static int efi_set_time(struct device *dev, struct rtc_time *tm)
{
efi_status_t status;
efi_time_t eft;
convert_to_efi_time(tm, &eft);
status = efi.set_time(&eft);
return status == EFI_SUCCESS ? 0 : -EINVAL;
}
static const struct rtc_class_ops efi_rtc_ops = {
.read_time = efi_read_time,
.set_time = efi_set_time,
.read_alarm = efi_read_alarm,
.set_alarm = efi_set_alarm,
};
static int __init efi_rtc_probe(struct platform_device *dev)
{
struct rtc_device *rtc;
rtc = devm_rtc_device_register(&dev->dev, "rtc-efi", &efi_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(dev, rtc);
return 0;
}
static struct platform_driver efi_rtc_driver = {
.driver = {
.name = "rtc-efi",
},
};
module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
MODULE_ALIAS("platform:rtc-efi");
MODULE_AUTHOR("dann frazier <dannf@hp.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("EFI RTC driver");
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