diff options
| author | Joshua Clayton <stillcompiling@gmail.com> | 2016-02-05 21:41:12 +0100 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@free-electrons.com> | 2016-03-14 17:08:16 +0100 |
| commit | 5495a4159f7413f0367e8c9727ba9facd40ade7f (patch) | |
| tree | 5bfdec7f3b6982a2c29c89762e8a20a50e579918 /drivers | |
| parent | rtc: Add functions to set and read rtc offset (diff) | |
| download | linux-5495a4159f7413f0367e8c9727ba9facd40ade7f.tar.xz linux-5495a4159f7413f0367e8c9727ba9facd40ade7f.zip | |
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.c | 35 |
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; } |