--- /dev/null
+/*
+ * 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
+name_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
+}
+static DEVICE_ATTR_RO(name);
+
+static ssize_t
+date_show(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 DEVICE_ATTR_RO(date);
+
+static ssize_t
+time_show(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 DEVICE_ATTR_RO(time);
+
+static ssize_t
+since_epoch_show(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 DEVICE_ATTR_RO(since_epoch);
+
+static ssize_t
+max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
+}
+
+static ssize_t
+max_user_freq_store(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 DEVICE_ATTR_RW(max_user_freq);
+
+/**
+ * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
+ *
+ * Returns 1 if the system clock was set by this RTC at the last
+ * boot or resume event.
+ */
+static ssize_t
+hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+#ifdef CONFIG_RTC_HCTOSYS_DEVICE
+ if (rtc_hctosys_ret == 0 &&
+ strcmp(dev_name(&to_rtc_device(dev)->dev),
+ CONFIG_RTC_HCTOSYS_DEVICE) == 0)
+ return sprintf(buf, "1\n");
+ else
+#endif
+ return sprintf(buf, "0\n");
+}
+static DEVICE_ATTR_RO(hctosys);
+
+static struct attribute *rtc_attrs[] = {
+ &dev_attr_name.attr,
+ &dev_attr_date.attr,
+ &dev_attr_time.attr,
+ &dev_attr_since_epoch.attr,
+ &dev_attr_max_user_freq.attr,
+ &dev_attr_hctosys.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(rtc);
+
+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;
+ unsigned long push = 0;
+ struct rtc_wkalrm alm;
+ struct rtc_device *rtc = to_rtc_device(dev);
+ char *buf_ptr;
+ int adjust = 0;
+
+ /* 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);
+
+ buf_ptr = (char *)buf;
+ if (*buf_ptr == '+') {
+ buf_ptr++;
+ if (*buf_ptr == '=') {
+ buf_ptr++;
+ push = 1;
+ } else
+ adjust = 1;
+ }
+ alarm = simple_strtoul(buf_ptr, NULL, 0);
+ if (adjust) {
+ alarm += now;
+ }
+ if (alarm > now || push) {
+ /* 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) {
+ if (push) {
+ rtc_tm_to_time(&alm.time, &push);
+ alarm += push;
+ } else
+ return -EBUSY;
+ } else if (push)
+ return -EINVAL;
+ 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_groups = rtc_groups;
+}
Code Review / kvmfornfv.git / blobdiff