/* * 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 rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%s\n", to_rtc_device(dev)->name); } static ssize_t rtc_sysfs_show_date(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 ssize_t rtc_sysfs_show_time(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 ssize_t rtc_sysfs_show_since_epoch(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) { unsigned long time; rtc_tm_to_time(&tm, &time); retval = sprintf(buf, "%lu\n", time); } return retval; } static ssize_t rtc_sysfs_show_max_user_freq(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq); } static ssize_t rtc_sysfs_set_max_user_freq(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) { struct rtc_device *rtc = to_rtc_device(dev); unsigned long val = simple_strtoul(buf, NULL, 0); if (val >= 4096 || val == 0) return -EINVAL; rtc->max_user_freq = (int)val; return n; } static struct device_attribute rtc_attrs[] = { __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL), __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL), __ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL), __ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL), __ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq, rtc_sysfs_set_max_user_freq), { }, }; static ssize_t rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; unsigned long 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) { rtc_tm_to_time(&alm.time, &alarm); retval = sprintf(buf, "%lu\n", alarm); } return retval; } static ssize_t rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) { ssize_t retval; unsigned long now, alarm; struct rtc_wkalrm alm; struct rtc_device *rtc = to_rtc_device(dev); /* 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; rtc_tm_to_time(&alm.time, &now); alarm = simple_strtoul(buf, NULL, 0); if (alarm > now) { /* 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) return -EBUSY; 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_time_to_tm(alarm, &alm.time); retval = rtc_set_alarm(rtc, &alm); return (retval < 0) ? retval : n; } static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR, rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm); /* 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 inline int rtc_does_wakealarm(struct rtc_device *rtc) { if (!device_can_wakeup(rtc->dev.parent)) return 0; return rtc->ops->set_alarm != NULL; } void rtc_sysfs_add_device(struct rtc_device *rtc) { int err; /* not all RTCs support both alarms and wakeup */ if (!rtc_does_wakealarm(rtc)) return; err = device_create_file(&rtc->dev, &dev_attr_wakealarm); if (err) dev_err(rtc->dev.parent, "failed to create alarm attribute, %d\n", err); } void rtc_sysfs_del_device(struct rtc_device *rtc) { /* REVISIT did we add it successfully? */ if (rtc_does_wakealarm(rtc)) device_remove_file(&rtc->dev, &dev_attr_wakealarm); } void __init rtc_sysfs_init(struct class *rtc_class) { rtc_class->dev_attrs = rtc_attrs; }