249 lines
6.0 KiB
C
249 lines
6.0 KiB
C
/*
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* RTC subsystem, sysfs interface
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*
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* Copyright (C) 2005 Tower Technologies
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* Author: Alessandro Zummo <a.zummo@towertech.it>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/rtc.h>
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#include "rtc-core.h"
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/* device attributes */
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/*
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* NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
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* ideally UTC. However, PCs that also boot to MS-Windows normally use
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* the local time and change to match daylight savings time. That affects
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* attributes including date, time, since_epoch, and wakealarm.
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*/
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static ssize_t
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rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
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}
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static ssize_t
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rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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ssize_t retval;
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struct rtc_time tm;
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retval = rtc_read_time(to_rtc_device(dev), &tm);
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if (retval == 0) {
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retval = sprintf(buf, "%04d-%02d-%02d\n",
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tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
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}
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return retval;
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}
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static ssize_t
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rtc_sysfs_show_time(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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ssize_t retval;
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struct rtc_time tm;
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retval = rtc_read_time(to_rtc_device(dev), &tm);
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if (retval == 0) {
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retval = sprintf(buf, "%02d:%02d:%02d\n",
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tm.tm_hour, tm.tm_min, tm.tm_sec);
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}
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return retval;
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}
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static ssize_t
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rtc_sysfs_show_since_epoch(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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ssize_t retval;
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struct rtc_time tm;
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retval = rtc_read_time(to_rtc_device(dev), &tm);
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if (retval == 0) {
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unsigned long time;
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rtc_tm_to_time(&tm, &time);
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retval = sprintf(buf, "%lu\n", time);
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}
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return retval;
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}
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static ssize_t
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rtc_sysfs_show_max_user_freq(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
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}
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static ssize_t
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rtc_sysfs_set_max_user_freq(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t n)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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unsigned long val = simple_strtoul(buf, NULL, 0);
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if (val >= 4096 || val == 0)
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return -EINVAL;
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rtc->max_user_freq = (int)val;
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return n;
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}
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static ssize_t
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rtc_sysfs_show_hctosys(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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#ifdef CONFIG_RTC_HCTOSYS_DEVICE
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if (strcmp(dev_name(&to_rtc_device(dev)->dev),
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CONFIG_RTC_HCTOSYS_DEVICE) == 0)
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return sprintf(buf, "1\n");
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else
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#endif
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return sprintf(buf, "0\n");
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}
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static struct device_attribute rtc_attrs[] = {
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__ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
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__ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
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__ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
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__ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
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__ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq,
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rtc_sysfs_set_max_user_freq),
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__ATTR(hctosys, S_IRUGO, rtc_sysfs_show_hctosys, NULL),
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{ },
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};
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static ssize_t
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rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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ssize_t retval;
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unsigned long alarm;
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struct rtc_wkalrm alm;
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/* Don't show disabled alarms. For uniformity, RTC alarms are
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* conceptually one-shot, even though some common RTCs (on PCs)
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* don't actually work that way.
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*
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* NOTE: RTC implementations where the alarm doesn't match an
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* exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
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* alarms after they trigger, to ensure one-shot semantics.
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*/
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retval = rtc_read_alarm(to_rtc_device(dev), &alm);
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if (retval == 0 && alm.enabled) {
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rtc_tm_to_time(&alm.time, &alarm);
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retval = sprintf(buf, "%lu\n", alarm);
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}
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return retval;
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}
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static ssize_t
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rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t n)
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{
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ssize_t retval;
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unsigned long now, alarm;
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struct rtc_wkalrm alm;
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struct rtc_device *rtc = to_rtc_device(dev);
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char *buf_ptr;
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int adjust = 0;
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/* Only request alarms that trigger in the future. Disable them
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* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
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*/
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retval = rtc_read_time(rtc, &alm.time);
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if (retval < 0)
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return retval;
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rtc_tm_to_time(&alm.time, &now);
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buf_ptr = (char *)buf;
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if (*buf_ptr == '+') {
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buf_ptr++;
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adjust = 1;
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}
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alarm = simple_strtoul(buf_ptr, NULL, 0);
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if (adjust) {
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alarm += now;
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}
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if (alarm > now) {
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/* Avoid accidentally clobbering active alarms; we can't
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* entirely prevent that here, without even the minimal
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* locking from the /dev/rtcN api.
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*/
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retval = rtc_read_alarm(rtc, &alm);
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if (retval < 0)
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return retval;
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if (alm.enabled)
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return -EBUSY;
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alm.enabled = 1;
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} else {
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alm.enabled = 0;
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/* Provide a valid future alarm time. Linux isn't EFI,
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* this time won't be ignored when disabling the alarm.
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*/
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alarm = now + 300;
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}
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rtc_time_to_tm(alarm, &alm.time);
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retval = rtc_set_alarm(rtc, &alm);
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return (retval < 0) ? retval : n;
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}
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static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
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rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
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/* The reason to trigger an alarm with no process watching it (via sysfs)
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* is its side effect: waking from a system state like suspend-to-RAM or
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* suspend-to-disk. So: no attribute unless that side effect is possible.
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* (Userspace may disable that mechanism later.)
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*/
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static inline int rtc_does_wakealarm(struct rtc_device *rtc)
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{
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if (!device_can_wakeup(rtc->dev.parent))
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return 0;
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return rtc->ops->set_alarm != NULL;
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}
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void rtc_sysfs_add_device(struct rtc_device *rtc)
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{
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int err;
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/* not all RTCs support both alarms and wakeup */
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if (!rtc_does_wakealarm(rtc))
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return;
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err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
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if (err)
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dev_err(rtc->dev.parent,
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"failed to create alarm attribute, %d\n", err);
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}
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void rtc_sysfs_del_device(struct rtc_device *rtc)
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{
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/* REVISIT did we add it successfully? */
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if (rtc_does_wakealarm(rtc))
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device_remove_file(&rtc->dev, &dev_attr_wakealarm);
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}
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void __init rtc_sysfs_init(struct class *rtc_class)
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{
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rtc_class->dev_attrs = rtc_attrs;
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}
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