drivers/rtc/rtc-ab8500.c: use UIE emulation

RTC: Fix to correct improper implementation of clock update irq
(RTC_UIE) and enable UIE Emulation.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Ramesh Chandrasekaran <ramesh.chandrasekaran@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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/Kconfig

@@ -694,6 +694,7 @@ config RTC_DRV_AB3100
 config RTC_DRV_AB8500
 	tristate "ST-Ericsson AB8500 RTC"
 	depends on AB8500_CORE
+	select RTC_INTF_DEV_UIE_EMUL
 	help
 	  Select this to enable the ST-Ericsson AB8500 power management IC RTC
 	  support. This chip contains a battery- and capacitor-backed RTC.

drivers/rtc/rtc-ab8500.c

@@ -225,7 +225,8 @@ static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	int retval, i;
 	unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
-	unsigned long mins, secs = 0;
+	unsigned long mins, secs = 0, cursec = 0;
+	struct rtc_time curtm;
 
 	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 		dev_dbg(dev, "year should be equal to or greater than %d\n",
@@ -236,6 +237,18 @@ static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 	/* Get the number of seconds since 1970 */
 	rtc_tm_to_time(&alarm->time, &secs);
 
+	/*
+	 * Check whether alarm is set less than 1min.
+	 * Since our RTC doesn't support alarm resolution less than 1min,
+	 * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
+	 */
+	ab8500_rtc_read_time(dev, &curtm); /* Read current time */
+	rtc_tm_to_time(&curtm, &cursec);
+	if ((secs - cursec) < 59) {
+		dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 	 * we only have a small counter in the RTC.