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Subject[PATCH v2 7/8] rtc: implement a sysfs interface for clock offset
Date
The file is called "offset", and may be set and read in decimal.
For rtcs that do not have read_offset or set_offset implemented,
read always returns zero and write will return -EINVAL.

Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
---
drivers/rtc/interface.c | 2 +-
drivers/rtc/rtc-sysfs.c | 29 +++++++++++++++++++++++++++++
2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 57cd928..c064eb9 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -959,7 +959,7 @@ int rtc_read_offset(struct rtc_device *rtc, long *offset)
return -ENODEV;

if (!rtc->ops->set_offset) {
- offset = 0;
+ *offset = 0;
return 0;
}

diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 7273855..622a0dc 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -211,6 +211,34 @@ 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,
@@ -219,6 +247,7 @@ static struct attribute *rtc_attrs[] = {
&dev_attr_max_user_freq.attr,
&dev_attr_hctosys.attr,
&dev_attr_wakealarm.attr,
+ &dev_attr_offset.attr,
NULL,
};

--
2.5.0


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