1 files changed, 265 insertions, 0 deletions

diff --git a/kernel/drivers/rtc/rtc-sysfs.c b/kernel/drivers/rtc/rtc-sysfs.c
new file mode 100644
index 000000000..babd43bf3
--- /dev/null
+++ b/kernel/drivers/rtc/rtc-sysfs.c
@@ -0,0 +1,265 @@
+/*
+ * 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;
+}