rtc: ti-k3: Add support to resume from IO DDR low power mode

Restore the RTC HW context which may be lost when system enters
certain low power mode (IO+DDR mode).
Check if the RTC registers are locked which would indicate loss of
context (reset) and restore the context as needed.

Signed-off-by: Akashdeep Kaur <a-kaur@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://patch.msgid.link/20260313111740.1492519-1-a-kaur@ti.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: akashdeep-ti

drivers/rtc/rtc-ti-k3.c

@@ -640,10 +640,18 @@ static int __maybe_unused ti_k3_rtc_suspend(struct device *dev)
 static int __maybe_unused ti_k3_rtc_resume(struct device *dev)
 {
 	struct ti_k3_rtc *priv = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (k3rtc_check_unlocked(priv)) {
+		/* RTC locked implies low power mode exit where RTC loses context */
+		ret = k3rtc_configure(dev);
+		if (ret)
+			return ret;
+	}
 
 	if (device_may_wakeup(dev))
 		disable_irq_wake(priv->irq);
-	return 0;
+	return ret;
 }
 
 static SIMPLE_DEV_PM_OPS(ti_k3_rtc_pm_ops, ti_k3_rtc_suspend, ti_k3_rtc_resume);