// SPDX-License-Identifier: GPL-2.0
/*
* RTC subsystem, sysfs interface
*
* Copyright (C) 2005 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include "rtc-core.h"
/* device attributes */
/*
* NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
* ideally UTC. However, PCs that also boot to MS-Windows normally use
* the local time and change to match daylight savings time. That affects
* attributes including date, time, since_epoch, and wakealarm.
*/
static ssize_t
name_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
dev_name(dev->parent));
}
static DEVICE_ATTR_RO(name);
static ssize_t
date_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval)
return retval;
return sprintf(buf, "%ptRd\n", &tm);
}
static DEVICE_ATTR_RO(date);
static ssize_t
time_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval)
return retval;
return sprintf(buf, "%ptRt\n", &tm);
}
static DEVICE_ATTR_RO(time);
static ssize_t
since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
time64_t time;
time = rtc_tm_to_time64(&tm);
retval = sprintf(buf, "%lld\n", time);
}
return retval;
}
static DEVICE_ATTR_RO(since_epoch);
static ssize_t
max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
}
static ssize_t
max_user_freq_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
struct rtc_device *rtc = to_rtc_device(dev);
unsigned long val;
int err;
err = kstrtoul(buf, 0, &val);
if (err)
return err;
if (val >= 4096 || val == 0)
return -EINVAL;
rtc->max_user_freq = (int)val;
return n;
}
static DEVICE_ATTR_RW(max_user_freq);
/**
* rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
*
* Returns 1 if the system clock was set by this RTC at the last
* boot or resume event.
*/
static ssize_t
hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
{
#ifdef CONFIG_RTC_HCTOSYS_DEVICE
if (rtc_hctosys_ret == 0 &&
strcmp(dev_name(&to_rtc_device(dev)->dev),
CONFIG_RTC_HCTOSYS_DEVICE) == 0)
return sprintf(buf, "1\n");
#endif
return sprintf(buf, "0\n");
}
static DEVICE_ATTR_RO(hctosys);
static ssize_t
wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
time64_t alarm;
struct rtc_wkalrm alm;
/* Don't show disabled alarms. For uniformity, RTC alarms are
* conceptually one-shot, even though some common RTCs (on PCs)
* don't actually work that way.
*
* NOTE: RTC implementations where the alarm doesn't match an
* exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
* alarms after they trigger, to ensure one-shot semantics.
*/
retval = rtc_read_alarm(to_rtc_device(dev), &alm);
if (retval == 0 && alm.enabled) {
alarm = rtc_tm_to_time64(&alm.time);
retval = sprintf(buf, "%lld\n", alarm);
}
return retval;
}
static ssize_t
wakealarm_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
ssize_t retval;
time64_t now, alarm;
time64_t push = 0;
struct rtc_wkalrm alm;
struct rtc_device *rtc = to_rtc_device(dev);
const char *buf_ptr;
int adjust = 0;
/* Only request alarms that trigger in the future. Disable them
* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
*/
retval = rtc_read_time(rtc, &alm.time);
if (retval < 0)
return retval;
now = rtc_tm_to_time64(&alm.time);
buf_ptr = buf;
if (*buf_ptr == '+') {
buf_ptr++;
if (*buf_ptr == '=') {
buf_ptr++;
push = 1;
} else {
adjust = 1;
}
}
retval = kstrtos64(buf_ptr, 0, &alarm);
if (retval)
return retval;
if (adjust)
alarm += now;
if (alarm > now || push) {
/* Avoid accidentally clobbering active alarms; we can't
* entirely prevent that here, without even the minimal
* locking from the /dev/rtcN api.
*/
retval = rtc_read_alarm(rtc, &alm);
if (retval < 0)
return retval;
if (alm.enabled) {
if (push) {
push = rtc_tm_to_time64(&alm.time);
alarm += push;
} else
return -EBUSY;
} else if (push)
return -EINVAL;
alm.enabled = 1;
} else {
alm.enabled = 0;
/* Provide a valid future alarm time. Linux isn't EFI,
* this time won't be ignored when disabling the alarm.
*/
alarm = now + 300;
}
rtc_time64_to_tm(alarm, &alm.time);
retval = rtc_set_alarm(rtc, &alm);
return (retval < 0) ? retval : n;
}
static DEVICE_ATTR_RW(wakealarm);
static ssize_t
offset_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
long offset;
retval = rtc_read_offset(to_rtc_device(dev), &offset);
if (retval == 0)
retval = sprintf(buf, "%ld\n", offset);
return retval;
}
static ssize_t
offset_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
ssize_t retval;
long offset;
retval = kstrtol(buf, 10, &offset);
if (retval == 0)
retval = rtc_set_offset(to_rtc_device(dev), offset);
return (retval < 0) ? retval : n;
}
static DEVICE_ATTR_RW(offset);
static ssize_t
range_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
to_rtc_device(dev)->range_max);
}
static DEVICE_ATTR_RO(range);
static struct attribute *rtc_attrs[] = {
&dev_attr_name.attr,
&dev_attr_date.attr,
&dev_attr_time.attr,
&dev_attr_since_epoch.attr,
&dev_attr_max_user_freq.attr,
&dev_attr_hctosys.attr,
&dev_attr_wakealarm.attr,
&dev_attr_offset.attr,
&dev_attr_range.attr,
NULL,
};
/* The reason to trigger an alarm with no process watching it (via sysfs)
* is its side effect: waking from a system state like suspend-to-RAM or
* suspend-to-disk. So: no attribute unless that side effect is possible.
* (Userspace may disable that mechanism later.)
*/
static bool rtc_does_wakealarm(struct rtc_device *rtc)
{
if (!device_can_wakeup(rtc->dev.parent))
return false;
return rtc->ops->set_alarm != NULL;
}
static umode_t rtc_attr_is_visible(struct kobject *kobj,
struct attribute *attr, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct rtc_device *rtc = to_rtc_device(dev);
umode_t mode = attr->mode;
if (attr == &dev_attr_wakealarm.attr) {
if (!rtc_does_wakealarm(rtc))
mode = 0;
} else if (attr == &dev_attr_offset.attr) {
if (!rtc->ops->set_offset)
mode = 0;
} else if (attr == &dev_attr_range.attr) {
if (!(rtc->range_max - rtc->range_min))
mode = 0;
}
return mode;
}
static struct attribute_group rtc_attr_group = {
.is_visible = rtc_attr_is_visible,
.attrs = rtc_attrs,
};
static const struct attribute_group *rtc_attr_groups[] = {
&rtc_attr_group,
NULL
};
const struct attribute_group **rtc_get_dev_attribute_groups(void)
{
return rtc_attr_groups;
}
int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)
{
size_t old_cnt = 0, add_cnt = 0, new_cnt;
const struct attribute_group **groups, **old;
if (rtc->registered)
return -EINVAL;
if (!grps)
return -EINVAL;
groups = rtc->dev.groups;
if (groups)
for (; *groups; groups++)
old_cnt++;
for (groups = grps; *groups; groups++)
add_cnt++;
new_cnt = old_cnt + add_cnt + 1;
groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);
if (!groups)
return -ENOMEM;
memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));
memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));
groups[old_cnt + add_cnt] = NULL;
old = rtc->dev.groups;
rtc->dev.groups = groups;
if (old && old != rtc_attr_groups)
devm_kfree(&rtc->dev, old);
return 0;
}
EXPORT_SYMBOL(rtc_add_groups);
int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
{
const struct attribute_group *groups[] = { grp, NULL };
return rtc_add_groups(rtc, groups);
}
EXPORT_SYMBOL(rtc_add_group);
