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rtc: Add RTC range

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Add a way for drivers to inform the core of the supported date/time range.
The core can then check whether the date/time or alarm is in the range
before calling ->set_time, ->set_mmss or ->set_alarm. It returns -ERANGE
when the time is out of range.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Alexandre Belloni 2018-02-17 14:58:40 +01:00
parent 236b718703
commit 71db049e73
4 changed files with 37 additions and 0 deletions
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8
Documentation/ABI/testing/sysfs-class-rtc
View File

@ -43,6 +43,14 @@ Contact: linux-rtc@vger.kernel.org
Description:
(RO) The name of the RTC corresponding to this sysfs directory
What: /sys/class/rtc/rtcX/range
Date: January 2018
KernelVersion: 4.16
Contact: linux-rtc@vger.kernel.org
Description:
Valid time range for the RTC, as seconds from epoch, formatted
as [min, max]
What: /sys/class/rtc/rtcX/since_epoch
Date: March 2006
KernelVersion: 2.6.17

14
drivers/rtc/interface.c
View File

@ -70,6 +70,13 @@ int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
if (err != 0)
return err;
if (rtc->range_min != rtc->range_max) {
time64_t time = rtc_tm_to_time64(tm);
if (time < rtc->range_min || time > rtc->range_max)
return -ERANGE;
}
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;
@ -374,6 +381,13 @@ int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
if (err != 0)
return err;
if (rtc->range_min != rtc->range_max) {
time64_t time = rtc_tm_to_time64(&alarm->time);
if (time < rtc->range_min || time > rtc->range_max)
return -ERANGE;
}
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;

12
drivers/rtc/rtc-sysfs.c
View File

@ -248,6 +248,14 @@ offset_store(struct device *dev, struct device_attribute *attr,
}
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,
@ -257,6 +265,7 @@ static struct attribute *rtc_attrs[] = {
&dev_attr_hctosys.attr,
&dev_attr_wakealarm.attr,
&dev_attr_offset.attr,
&dev_attr_range.attr,
NULL,
};
@ -286,6 +295,9 @@ static umode_t rtc_attr_is_visible(struct kobject *kobj,
} 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;

3
include/linux/rtc.h
View File

@ -150,6 +150,9 @@ struct rtc_device {
bool nvram_old_abi;
struct bin_attribute *nvram;
time64_t range_min;
timeu64_t range_max;
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
struct work_struct uie_task;
struct timer_list uie_timer;