drivers/rtc/sysfs.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, sysfs interface
  *
  * Copyright (C) 2005 Tower Technologies
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  */

 #include <linux/kstrtox.h>
 #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);

 /**
  * hctosys_show - indicate if the given RTC set the system time
  * @dev: The device that the attribute belongs to.
  * @attr: The attribute being read.
  * @buf: The result buffer.
  *
  * buf is "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 !!test_bit(RTC_FEATURE_ALARM, rtc->features);
 }

 static umode_t rtc_attr_is_visible(struct kobject *kobj,
 				   struct attribute *attr, int n)
 {
 	struct device *dev = kobj_to_dev(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 (!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);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* RTC subsystem, sysfs interface
	*
	* Copyright (C) 2005 Tower Technologies
	* Author: Alessandro Zummo <a.zummo@towertech.it>
	*/

	#include <linux/kstrtox.h>
	#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);

	/**
	* hctosys_show - indicate if the given RTC set the system time
	* @dev: The device that the attribute belongs to.
	* @attr: The attribute being read.
	* @buf: The result buffer.
	*
	* buf is "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 !!test_bit(RTC_FEATURE_ALARM, rtc->features);
	}

	static umode_t rtc_attr_is_visible(struct kobject *kobj,
	struct attribute *attr, int n)
	{
	struct device *dev = kobj_to_dev(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 (!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);