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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* rtc-efi: RTC Class Driver for EFI-based systems
*
* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
*
* Author: dann frazier <dannf@dannf.org>
* Based on efirtc.c by Stephane Eranian
*/
#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)
/*
* 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
*/
static int
compute_wday(efi_time_t *eft, int yday)
{
int ndays = eft->year * (365 % 7)
+ (eft->year - 1) / 4
- (eft->year - 1) / 100
+ (eft->year - 1) / 400
+ yday;
/*
* 1/1/0000 may or may not have been a Sunday (if it ever existed at
* all) but assuming it was makes this calculation work correctly.
*/
return ndays % 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;
if (eft->year < 1900 || eft->year > 9999)
return false;
wtime->tm_year = eft->year - 1900;
/* day in the year [1-365]*/
wtime->tm_yday = compute_yday(eft);
/* day of the week [0-6], Sunday=0 */
wtime->tm_wday = compute_wday(eft, wtime->tm_yday);
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 0;
}
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 int efi_procfs(struct device *dev, struct seq_file *seq)
{
efi_time_t eft, alm;
efi_time_cap_t cap;
efi_bool_t enabled, pending;
memset(&eft, 0, sizeof(eft));
memset(&alm, 0, sizeof(alm));
memset(&cap, 0, sizeof(cap));
efi.get_time(&eft, &cap);
efi.get_wakeup_time(&enabled, &pending, &alm);
seq_printf(seq,
"Time\t\t: %u:%u:%u.%09u\n"
"Date\t\t: %u-%u-%u\n"
"Daylight\t: %u\n",
eft.hour, eft.minute, eft.second, eft.nanosecond,
eft.year, eft.month, eft.day,
eft.daylight);
if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
seq_puts(seq, "Timezone\t: unspecified\n");
else
/* XXX fixme: convert to string? */
seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
seq_printf(seq,
"Alarm Time\t: %u:%u:%u.%09u\n"
"Alarm Date\t: %u-%u-%u\n"
"Alarm Daylight\t: %u\n"
"Enabled\t\t: %s\n"
"Pending\t\t: %s\n",
alm.hour, alm.minute, alm.second, alm.nanosecond,
alm.year, alm.month, alm.day,
alm.daylight,
enabled == 1 ? "yes" : "no",
pending == 1 ? "yes" : "no");
if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
seq_puts(seq, "Timezone\t: unspecified\n");
else
/* XXX fixme: convert to string? */
seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
/*
* now prints the capabilities
*/
seq_printf(seq,
"Resolution\t: %u\n"
"Accuracy\t: %u\n"
"SetstoZero\t: %u\n",
cap.resolution, cap.accuracy, cap.sets_to_zero);
return 0;
}
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,
.proc = efi_procfs,
};
static int __init efi_rtc_probe(struct platform_device *dev)
{
struct rtc_device *rtc;
efi_time_t eft;
efi_time_cap_t cap;
/* First check if the RTC is usable */
if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
return -ENODEV;
rtc = devm_rtc_allocate_device(&dev->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(dev, rtc);
rtc->ops = &efi_rtc_ops;
clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features);
return devm_rtc_register_device(rtc);
}
static struct platform_driver efi_rtc_driver = {
.driver = {
.name = "rtc-efi",
},
};
module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("EFI RTC driver");
MODULE_ALIAS("platform:rtc-efi");