Subject: RTC: Add the support for alarm time relative to current time in sysfs
>From : Zhao Yakui <yakui.zhao@xxxxxxxxx>
In current kernel if we want to set the alarm time, the absolute time
the seconds relative to 1970-01-01 00:00:00) should be written into
/sys/class/rtc/rtc0/wakealarm. It is not convenient.
It is more reasonable to add the support for the alarm time
relative to current RTC time.(the unit is second)
For example:
If the RTC is required to generate alarm after 2 minutes, the following will
be OK.
echo +120 > /sys/class/rtc/rtc0/wakealarm
or echo +0x78 > /sys/class/rtc/rtc0/wakealarm
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
drivers/rtc/rtc-sysfs.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
Index: linux-2.6/drivers/rtc/rtc-sysfs.c
===================================================================
--- linux-2.6.orig/drivers/rtc/rtc-sysfs.c
+++ linux-2.6/drivers/rtc/rtc-sysfs.c
@@ -145,6 +145,8 @@ rtc_sysfs_set_wakealarm(struct device *d
unsigned long now, alarm;
struct rtc_wkalrm alm;
struct rtc_device *rtc = to_rtc_device(dev);
+ char *buf_ptr;
+ int adjust = 0;
/* Only request alarms that trigger in the future. Disable them
* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
@@ -154,7 +156,15 @@ rtc_sysfs_set_wakealarm(struct device *d
return retval;
rtc_tm_to_time(&alm.time, &now);
- alarm = simple_strtoul(buf, NULL, 0);
+ buf_ptr = (char *)buf;
+ if (*buf_ptr == '+') {
+ buf_ptr++;
+ adjust = 1;
+ }
+ alarm = simple_strtoul(buf_ptr, NULL, 0);
+ if (adjust) {
+ alarm += now;
+ }
if (alarm > now) {
/* Avoid accidentally clobbering active alarms; we can't
* entirely prevent that here, without even the minimal
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