linux/drivers/rtc/rtc-sysfs.c
<<
>>
Prefs
   1/*
   2 * RTC subsystem, sysfs interface
   3 *
   4 * Copyright (C) 2005 Tower Technologies
   5 * Author: Alessandro Zummo <a.zummo@towertech.it>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10*/
  11
  12#include <linux/module.h>
  13#include <linux/rtc.h>
  14
  15#include "rtc-core.h"
  16
  17
  18/* device attributes */
  19
  20/*
  21 * NOTE:  RTC times displayed in sysfs use the RTC's timezone.  That's
  22 * ideally UTC.  However, PCs that also boot to MS-Windows normally use
  23 * the local time and change to match daylight savings time.  That affects
  24 * attributes including date, time, since_epoch, and wakealarm.
  25 */
  26
  27static ssize_t
  28rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr,
  29                char *buf)
  30{
  31        return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
  32}
  33
  34static ssize_t
  35rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr,
  36                char *buf)
  37{
  38        ssize_t retval;
  39        struct rtc_time tm;
  40
  41        retval = rtc_read_time(to_rtc_device(dev), &tm);
  42        if (retval == 0) {
  43                retval = sprintf(buf, "%04d-%02d-%02d\n",
  44                        tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
  45        }
  46
  47        return retval;
  48}
  49
  50static ssize_t
  51rtc_sysfs_show_time(struct device *dev, struct device_attribute *attr,
  52                char *buf)
  53{
  54        ssize_t retval;
  55        struct rtc_time tm;
  56
  57        retval = rtc_read_time(to_rtc_device(dev), &tm);
  58        if (retval == 0) {
  59                retval = sprintf(buf, "%02d:%02d:%02d\n",
  60                        tm.tm_hour, tm.tm_min, tm.tm_sec);
  61        }
  62
  63        return retval;
  64}
  65
  66static ssize_t
  67rtc_sysfs_show_since_epoch(struct device *dev, struct device_attribute *attr,
  68                char *buf)
  69{
  70        ssize_t retval;
  71        struct rtc_time tm;
  72
  73        retval = rtc_read_time(to_rtc_device(dev), &tm);
  74        if (retval == 0) {
  75                unsigned long time;
  76                rtc_tm_to_time(&tm, &time);
  77                retval = sprintf(buf, "%lu\n", time);
  78        }
  79
  80        return retval;
  81}
  82
  83static ssize_t
  84rtc_sysfs_show_max_user_freq(struct device *dev, struct device_attribute *attr,
  85                char *buf)
  86{
  87        return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
  88}
  89
  90static ssize_t
  91rtc_sysfs_set_max_user_freq(struct device *dev, struct device_attribute *attr,
  92                const char *buf, size_t n)
  93{
  94        struct rtc_device *rtc = to_rtc_device(dev);
  95        unsigned long val = simple_strtoul(buf, NULL, 0);
  96
  97        if (val >= 4096 || val == 0)
  98                return -EINVAL;
  99
 100        rtc->max_user_freq = (int)val;
 101
 102        return n;
 103}
 104
 105/**
 106 * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
 107 *
 108 * Returns 1 if the system clock was set by this RTC at the last
 109 * boot or resume event.
 110 */
 111static ssize_t
 112rtc_sysfs_show_hctosys(struct device *dev, struct device_attribute *attr,
 113                char *buf)
 114{
 115#ifdef CONFIG_RTC_HCTOSYS_DEVICE
 116        if (rtc_hctosys_ret == 0 &&
 117                        strcmp(dev_name(&to_rtc_device(dev)->dev),
 118                                CONFIG_RTC_HCTOSYS_DEVICE) == 0)
 119                return sprintf(buf, "1\n");
 120        else
 121#endif
 122                return sprintf(buf, "0\n");
 123}
 124
 125static struct device_attribute rtc_attrs[] = {
 126        __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
 127        __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
 128        __ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
 129        __ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
 130        __ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq,
 131                        rtc_sysfs_set_max_user_freq),
 132        __ATTR(hctosys, S_IRUGO, rtc_sysfs_show_hctosys, NULL),
 133        { },
 134};
 135
 136static ssize_t
 137rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
 138                char *buf)
 139{
 140        ssize_t retval;
 141        unsigned long alarm;
 142        struct rtc_wkalrm alm;
 143
 144        /* Don't show disabled alarms.  For uniformity, RTC alarms are
 145         * conceptually one-shot, even though some common RTCs (on PCs)
 146         * don't actually work that way.
 147         *
 148         * NOTE: RTC implementations where the alarm doesn't match an
 149         * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
 150         * alarms after they trigger, to ensure one-shot semantics.
 151         */
 152        retval = rtc_read_alarm(to_rtc_device(dev), &alm);
 153        if (retval == 0 && alm.enabled) {
 154                rtc_tm_to_time(&alm.time, &alarm);
 155                retval = sprintf(buf, "%lu\n", alarm);
 156        }
 157
 158        return retval;
 159}
 160
 161static ssize_t
 162rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
 163                const char *buf, size_t n)
 164{
 165        ssize_t retval;
 166        unsigned long now, alarm;
 167        struct rtc_wkalrm alm;
 168        struct rtc_device *rtc = to_rtc_device(dev);
 169        char *buf_ptr;
 170        int adjust = 0;
 171
 172        /* Only request alarms that trigger in the future.  Disable them
 173         * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
 174         */
 175        retval = rtc_read_time(rtc, &alm.time);
 176        if (retval < 0)
 177                return retval;
 178        rtc_tm_to_time(&alm.time, &now);
 179
 180        buf_ptr = (char *)buf;
 181        if (*buf_ptr == '+') {
 182                buf_ptr++;
 183                adjust = 1;
 184        }
 185        alarm = simple_strtoul(buf_ptr, NULL, 0);
 186        if (adjust) {
 187                alarm += now;
 188        }
 189        if (alarm > now) {
 190                /* Avoid accidentally clobbering active alarms; we can't
 191                 * entirely prevent that here, without even the minimal
 192                 * locking from the /dev/rtcN api.
 193                 */
 194                retval = rtc_read_alarm(rtc, &alm);
 195                if (retval < 0)
 196                        return retval;
 197                if (alm.enabled)
 198                        return -EBUSY;
 199
 200                alm.enabled = 1;
 201        } else {
 202                alm.enabled = 0;
 203
 204                /* Provide a valid future alarm time.  Linux isn't EFI,
 205                 * this time won't be ignored when disabling the alarm.
 206                 */
 207                alarm = now + 300;
 208        }
 209        rtc_time_to_tm(alarm, &alm.time);
 210
 211        retval = rtc_set_alarm(rtc, &alm);
 212        return (retval < 0) ? retval : n;
 213}
 214static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
 215                rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
 216
 217
 218/* The reason to trigger an alarm with no process watching it (via sysfs)
 219 * is its side effect:  waking from a system state like suspend-to-RAM or
 220 * suspend-to-disk.  So: no attribute unless that side effect is possible.
 221 * (Userspace may disable that mechanism later.)
 222 */
 223static inline int rtc_does_wakealarm(struct rtc_device *rtc)
 224{
 225        if (!device_can_wakeup(rtc->dev.parent))
 226                return 0;
 227        return rtc->ops->set_alarm != NULL;
 228}
 229
 230
 231void rtc_sysfs_add_device(struct rtc_device *rtc)
 232{
 233        int err;
 234
 235        /* not all RTCs support both alarms and wakeup */
 236        if (!rtc_does_wakealarm(rtc))
 237                return;
 238
 239        err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
 240        if (err)
 241                dev_err(rtc->dev.parent,
 242                        "failed to create alarm attribute, %d\n", err);
 243}
 244
 245void rtc_sysfs_del_device(struct rtc_device *rtc)
 246{
 247        /* REVISIT did we add it successfully? */
 248        if (rtc_does_wakealarm(rtc))
 249                device_remove_file(&rtc->dev, &dev_attr_wakealarm);
 250}
 251
 252void __init rtc_sysfs_init(struct class *rtc_class)
 253{
 254        rtc_class->dev_attrs = rtc_attrs;
 255}
 256
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.