273 lines
6.4 KiB
C
273 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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name_show(struct device *dev, struct device_attribute *attr, 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 DEVICE_ATTR_RO(name);
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static ssize_t
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date_show(struct device *dev, struct device_attribute *attr, 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 DEVICE_ATTR_RO(date);
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static ssize_t
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time_show(struct device *dev, struct device_attribute *attr, 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 DEVICE_ATTR_RO(time);
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static ssize_t
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since_epoch_show(struct device *dev, struct device_attribute *attr, 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 DEVICE_ATTR_RO(since_epoch);
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static ssize_t
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max_user_freq_show(struct device *dev, struct device_attribute *attr, 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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max_user_freq_store(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;
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int err;
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err = kstrtoul(buf, 0, &val);
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if (err)
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return err;
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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 DEVICE_ATTR_RW(max_user_freq);
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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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hctosys_show(struct device *dev, struct device_attribute *attr, 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 DEVICE_ATTR_RO(hctosys);
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static ssize_t
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wakealarm_show(struct device *dev, struct device_attribute *attr, 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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wakealarm_store(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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retval = kstrtoul(buf_ptr, 0, &alarm);
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if (retval)
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return retval;
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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_RW(wakealarm);
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static struct attribute *rtc_attrs[] = {
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&dev_attr_name.attr,
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&dev_attr_date.attr,
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&dev_attr_time.attr,
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&dev_attr_since_epoch.attr,
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&dev_attr_max_user_freq.attr,
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&dev_attr_hctosys.attr,
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&dev_attr_wakealarm.attr,
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NULL,
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};
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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 bool 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 false;
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return rtc->ops->set_alarm != NULL;
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}
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static umode_t rtc_attr_is_visible(struct kobject *kobj,
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struct attribute *attr, int n)
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{
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struct device *dev = container_of(kobj, struct device, kobj);
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struct rtc_device *rtc = to_rtc_device(dev);
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umode_t mode = attr->mode;
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if (attr == &dev_attr_wakealarm.attr)
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if (!rtc_does_wakealarm(rtc))
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mode = 0;
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return mode;
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}
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static struct attribute_group rtc_attr_group = {
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.is_visible = rtc_attr_is_visible,
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.attrs = rtc_attrs,
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};
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static const struct attribute_group *rtc_attr_groups[] = {
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&rtc_attr_group,
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NULL
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};
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const struct attribute_group **rtc_get_dev_attribute_groups(void)
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{
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return rtc_attr_groups;
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}
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