rtc: implement a sysfs interface for clock offset (5495a415) · Commits · 戴 / test

Documentation/rtc.txt

+6 −0

Original line number	Diff line number	Diff line
		@@ -157,6 +157,12 @@ wakealarm: The time at which the clock will generate a system wakeup
		the epoch by default, or if there's a leading +, seconds in the
		future, or if there is a leading +=, seconds ahead of the current
		alarm.
		offset: The amount which the rtc clock has been adjusted in firmware.
		Visible only if the driver supports clock offset adjustment.
		The unit is parts per billion, i.e. The number of clock ticks
		which are added to or removed from the rtc's base clock per
		billion ticks. A positive value makes a day pass more slowly,
		longer, and a negative value makes a day pass more quickly.

		IOCTL INTERFACE
		---------------

+34 −1

Original line number	Diff line number	Diff line
		@@ -218,6 +218,34 @@ wakealarm_store(struct device dev, struct device_attribute attr,
		}
		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 struct attribute *rtc_attrs[] = {
		&dev_attr_name.attr,
		&dev_attr_date.attr,
		@@ -226,6 +254,7 @@ static struct attribute *rtc_attrs[] = {
		&dev_attr_max_user_freq.attr,
		&dev_attr_hctosys.attr,
		&dev_attr_wakealarm.attr,
		&dev_attr_offset.attr,
		NULL,
		};

		@@ -249,9 +278,13 @@ static umode_t rtc_attr_is_visible(struct kobject *kobj,
		struct rtc_device *rtc = to_rtc_device(dev);
		umode_t mode = attr->mode;

		if (attr == &dev_attr_wakealarm.attr)
		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;
		}

		return mode;
		}