rtc: omap: Cut down the shutdown time from 2 seconds to 1 sec

Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
over try again.
Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-omap.c

@@ -421,12 +421,6 @@ static struct omap_rtc *omap_rtc_power_off_rtc;
  * The RTC can be used to control an external PMIC via the pmic_power_en pin,
  * which can be configured to transition to OFF on ALARM2 events.
  *
- * Notes:
- * The two-second alarm offset is the shortest offset possible as the alarm
- * registers must be set before the next timer update and the offset
- * calculation is too heavy for everything to be done within a single access
- * period (~15 us).
- *
  * Called with local interrupts disabled.
  */
 static void omap_rtc_power_off(void)
@@ -434,6 +428,7 @@ static void omap_rtc_power_off(void)
 	struct omap_rtc *rtc = omap_rtc_power_off_rtc;
 	struct rtc_time tm;
 	unsigned long now;
+	int seconds;
 	u32 val;
 
 	rtc->type->unlock(rtc);
@@ -441,11 +436,13 @@ static void omap_rtc_power_off(void)
 	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
 	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
 
-	/* set alarm two seconds from now */
+again:
+	/* set alarm one second from now */
 	omap_rtc_read_time_raw(rtc, &tm);
+	seconds = tm.tm_sec;
 	bcd2tm(&tm);
 	rtc_tm_to_time(&tm, &now);
-	rtc_time_to_tm(now + 2, &tm);
+	rtc_time_to_tm(now + 1, &tm);
 
 	if (tm2bcd(&tm) < 0) {
 		dev_err(&rtc->rtc->dev, "power off failed\n");
@@ -470,14 +467,22 @@ static void omap_rtc_power_off(void)
 	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
 	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
 			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
+
+	/* Retry in case roll over happened before alarm was armed. */
+	if (rtc_read(rtc, OMAP_RTC_SECONDS_REG) != seconds) {
+		val = rtc_read(rtc, OMAP_RTC_STATUS_REG);
+		if (!(val & OMAP_RTC_STATUS_ALARM2))
+			goto again;
+	}
+
 	rtc->type->lock(rtc);
 
 	/*
-	 * Wait for alarm to trigger (within two seconds) and external PMIC to
+	 * Wait for alarm to trigger (within one second) and external PMIC to
 	 * power off the system. Add a 500 ms margin for external latencies
 	 * (e.g. debounce circuits).
 	 */
-	mdelay(2500);
+	mdelay(1500);
 }
 
 static const struct rtc_class_ops omap_rtc_ops = {