This adds in the ability for the rtc sysfs code to handle += characters
at the beginning of a wakealarm setting string. This will allow the user to
attempt to push out an existing wakealarm by a provided amount.
In the case that the += characters are provided but the alarm is not active
-EVINVAL is returned.
Signed-off-by: Bernie Thompson <bhthompson@xxxxxxxxxxxx>
---
Documentation/rtc.txt | 7 ++++---
drivers/rtc/rtc-sysfs.c | 20 +++++++++++++++-----
2 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index 32aa400..596b60c 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -153,9 +153,10 @@ since_epoch: The number of seconds since the epoch according to the RTC
time: RTC-provided time
wakealarm: The time at which the clock will generate a system wakeup
event. This is a one shot wakeup event, so must be reset
- after wake if a daily wakeup is required. Format is either
- seconds since the epoch or, if there's a leading +, seconds
- in the future.
+ after wake if a daily wakeup is required. Format is seconds since
+ the epoch by default, or if there's a leading +, seconds in the
+ future, or if there is a leading +=, seconds ahead of the current
+ alarm.
IOCTL INTERFACE
---------------
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index b70e2bb..4b26f86 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -164,6 +164,7 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
{
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;
@@ -180,13 +181,17 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
buf_ptr = (char *)buf;
if (*buf_ptr == '+') {
buf_ptr++;
- adjust = 1;
+ if (*buf_ptr == '=') {
+ buf_ptr++;
+ push = 1;
+ } else
+ adjust = 1;
}
alarm = simple_strtoul(buf_ptr, NULL, 0);
if (adjust) {
alarm += now;
}
- if (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.
@@ -194,9 +199,14 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
retval = rtc_read_alarm(rtc, &alm);
if (retval < 0)
return retval;
- if (alm.enabled)
- return -EBUSY;
-
+ 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;
--
1.8.2.1
--
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