![Bernie Thompson](/assets/img/avatar_default.png)
This adds the ability for the rtc sysfs code to handle += characters at the beginning of a wakealarm setting string. This will allow the user to attempt to push out an existing wakealarm by a provided amount. In the case that the += characters are provided but the alarm is not active -EINVAL is returned. his is useful, at least for my purposes in suspend/resume testing. The basic test goes something like: 1. Set a wake alarm from userspace 5 seconds in the future 2. Start the suspend process (echo mem > /sys/power/state) 3. After ~2.5 seconds if userspace is still running (using another thread to check this), move the wake alarm 5 more seconds If the "move" involves an unset of the wakealarm then there's a period of time where the system is midway through suspending but has no wake alarm. It will get stuck. We'd rather not remove the "move" since the idea is to avoid a cancelled suspend when the alarm fires _during_ suspend. It is difficult for the test to tell the difference between a suspend that was cancelled because the alarm fired too early and a suspend that was Signed-off-by: Bernie Thompson <bhthompson@chromium.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Doug Anderson <dianders@chromium.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
266 lines
6.4 KiB
C
266 lines
6.4 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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/**
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* rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
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*
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* Returns 1 if the system clock was set by this RTC at the last
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* boot or resume event.
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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 (rtc_hctosys_ret == 0 &&
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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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unsigned long push = 0;
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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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if (*buf_ptr == '=') {
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buf_ptr++;
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push = 1;
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} else
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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 || push) {
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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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if (push) {
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rtc_tm_to_time(&alm.time, &push);
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alarm += push;
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} else
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return -EBUSY;
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} else if (push)
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return -EINVAL;
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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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