rtc: add the support for alarm time relative to current time in sysfs
authorZhao Yakui <yakui.zhao@intel.com>
Mon, 28 Apr 2008 09:11:58 +0000 (02:11 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 28 Apr 2008 15:58:17 +0000 (08:58 -0700)
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@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/rtc/rtc-sysfs.c

index 4d27ccc4fc069c174d5785ddfa7ad27aa55b35b4..2531ce4c9db082d94cd3b1afba7ac7f4acf93f85 100644 (file)
@@ -145,6 +145,8 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
        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 *dev, struct device_attribute *attr,
                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