linux/drivers/rtc/rtc-efi.c
Ard Biesheuvel 668a2abf91 rtc: efi: Avoid spamming the log on RTC read failure
There are cases where the EFI runtime services may end up in a funny
state, e.g., due to a crash in the variable services, and this affects
other EFI runtime services as well.

That means that, even though GetTime() should not return an error, there
are cases where it might, and there is no point in logging such an
occurrence multiple times.

This works around an issue where user space -apparently- keeps hitting
on /dev/rtc if it fails to read the h/w clock, resulting in a tsunami of
log spam and a non-responsive system as a result.

Cc: Pierre Gondois <pierre.gondois@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/all/Y2o1hdZK9GGDVJsS@monolith.localdoman/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20230217142338.1444509-1-ardb@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2023-02-22 21:07:53 +01:00

297 lines
6.7 KiB
C

// 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_once(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;
struct rtc_device *rtc = dev_get_drvdata(dev);
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);
if (test_bit(RTC_FEATURE_ALARM, rtc->features)) {
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);
if (efi_rt_services_supported(EFI_RT_SUPPORTED_WAKEUP_SERVICES))
set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features);
else
clear_bit(RTC_FEATURE_ALARM, rtc->features);
device_init_wakeup(&dev->dev, true);
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");