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authorJoshua Clayton <stillcompiling@gmail.com>2016-02-05 23:41:12 +0300
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-03-14 19:08:16 +0300
commit5495a4159f7413f0367e8c9727ba9facd40ade7f (patch)
tree5bfdec7f3b6982a2c29c89762e8a20a50e579918 /drivers
parentb3967067c273359c7462f4be9a887c3d1a515f49 (diff)
downloadlinux-5495a4159f7413f0367e8c9727ba9facd40ade7f.tar.xz
rtc: implement a sysfs interface for clock offset
clock offset may be set and read in decimal parts per billion attribute is /sys/class/rtc/rtcN/offset The attribute is only visible for rtcs that have set_offset implemented. Signed-off-by: Joshua Clayton <stillcompiling@gmail.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/rtc/rtc-sysfs.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 463e286064ab..63b9fb1318c2 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -218,6 +218,34 @@ wakealarm_store(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RW(wakealarm);
+static ssize_t
+offset_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ ssize_t retval;
+ long offset;
+
+ retval = rtc_read_offset(to_rtc_device(dev), &offset);
+ if (retval == 0)
+ retval = sprintf(buf, "%ld\n", offset);
+
+ return retval;
+}
+
+static ssize_t
+offset_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t n)
+{
+ ssize_t retval;
+ long offset;
+
+ retval = kstrtol(buf, 10, &offset);
+ if (retval == 0)
+ retval = rtc_set_offset(to_rtc_device(dev), offset);
+
+ return (retval < 0) ? retval : n;
+}
+static DEVICE_ATTR_RW(offset);
+
static struct attribute *rtc_attrs[] = {
&dev_attr_name.attr,
&dev_attr_date.attr,
@@ -226,6 +254,7 @@ static struct attribute *rtc_attrs[] = {
&dev_attr_max_user_freq.attr,
&dev_attr_hctosys.attr,
&dev_attr_wakealarm.attr,
+ &dev_attr_offset.attr,
NULL,
};
@@ -249,9 +278,13 @@ static umode_t rtc_attr_is_visible(struct kobject *kobj,
struct rtc_device *rtc = to_rtc_device(dev);
umode_t mode = attr->mode;
- if (attr == &dev_attr_wakealarm.attr)
+ if (attr == &dev_attr_wakealarm.attr) {
if (!rtc_does_wakealarm(rtc))
mode = 0;
+ } else if (attr == &dev_attr_offset.attr) {
+ if (!rtc->ops->set_offset)
+ mode = 0;
+ }
return mode;
}