2 files changed, 16 insertions, 0 deletions

diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index 2745e8197fde..9104c1062084 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -143,6 +143,8 @@ rtc attributes without requiring the use of ioctls. All dates and times
 are in the RTC's timezone, rather than in system time.
 
 date:            RTC-provided date
+hctosys:         1 if the RTC provided the system time at boot via the
+                 CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
 max_user_freq:   The maximum interrupt rate an unprivileged user may request
                  from this RTC.
 name:            The name of the RTC corresponding to this sysfs directory
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 2531ce4c9db0..7dd23a6fc825 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -102,6 +102,19 @@ rtc_sysfs_set_max_user_freq(struct device *dev, struct device_attribute *attr,
         return n;
 }
 
+static ssize_t
+rtc_sysfs_show_hctosys(struct device *dev, struct device_attribute *attr,
+                char *buf)
+{
+#ifdef CONFIG_RTC_HCTOSYS_DEVICE
+        if (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 struct device_attribute rtc_attrs[] = {
         __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
         __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
@@ -109,6 +122,7 @@ static struct device_attribute rtc_attrs[] = {
         __ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
         __ATTR(max_user_freq, S_IRUGO | S_IWUSR, rtc_sysfs_show_max_user_freq,
                         rtc_sysfs_set_max_user_freq),
+        __ATTR(hctosys, S_IRUGO, rtc_sysfs_show_hctosys, NULL),
         { },
 };