Subject: + rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs.patch added to -mm tree
To: bhthompson@xxxxxxxxxxxx,a.zummo@xxxxxxxxxxxx,dianders@xxxxxxxxxxxx,rjw@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 22 May 2013 15:20:14 -0700
The patch titled
Subject: rtc: add ability to push out an existing wakealarm using sysfs
has been added to the -mm tree. Its filename is
rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs.patch
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------------------------------------------------------
From: Bernie Thompson <bhthompson@xxxxxxxxxxxx>
Subject: rtc: add ability to push out an existing wakealarm using sysfs
This adds 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 -EINVAL is returned.
his is useful, at least for my purposes in suspend/resume testing. The
basic test goes something like:
1. Set a wake alarm from userspace 5 seconds in the future
2. Start the suspend process (echo mem > /sys/power/state)
3. After ~2.5 seconds if userspace is still running (using another
thread to check this), move the wake alarm 5 more seconds
If the "move" involves an unset of the wakealarm then there's a period
of time where the system is midway through suspending but has no wake
alarm. It will get stuck.
We'd rather not remove the "move" since the idea is to avoid a
cancelled suspend when the alarm fires _during_ suspend. It is
difficult for the test to tell the difference between a suspend that
was cancelled because the alarm fired too early and a suspend that was
Signed-off-by: Bernie Thompson <bhthompson@xxxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Doug Anderson <dianders@xxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/rtc.txt | 7 ++++---
drivers/rtc/rtc-sysfs.c | 20 +++++++++++++++-----
2 files changed, 19 insertions(+), 8 deletions(-)
diff -puN Documentation/rtc.txt~rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs Documentation/rtc.txt
--- a/Documentation/rtc.txt~rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs
+++ a/Documentation/rtc.txt
@@ -153,9 +153,10 @@ since_epoch: The number of seconds sinc
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 -puN drivers/rtc/rtc-sysfs.c~rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs drivers/rtc/rtc-sysfs.c
--- a/drivers/rtc/rtc-sysfs.c~rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs
+++ a/drivers/rtc/rtc-sysfs.c
@@ -164,6 +164,7 @@ rtc_sysfs_set_wakealarm(struct device *d
{
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 *d
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 *d
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;
_
Patches currently in -mm which might be from bhthompson@xxxxxxxxxxxx are
rtc-add-ability-to-push-out-an-existing-wakealarm-using-sysfs.patch
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