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- /*
- * RTC subsystem, sysfs interface
- *
- * Copyright (C) 2005 Tower Technologies
- * Author: Alessandro Zummo <a.zummo@towertech.it>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
- #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 == 0) {
- retval = sprintf(buf, "%04d-%02d-%02d\n",
- tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
- }
- return retval;
- }
- 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 == 0) {
- retval = sprintf(buf, "%02d:%02d:%02d\n",
- tm.tm_hour, tm.tm_min, tm.tm_sec);
- }
- return retval;
- }
- 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");
- else
- #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);
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