rtc: m41t80: constify m41t80_rtc_ops

Use RTC_FEATURE_ALARM to signal to the core whether alarms are available
instead of changing the global struct rtc_class_ops, allowing to make it
const.

Signed-off-by: Alexandre Belloni <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/rtc/rtc-m41t80.c

···
 	return 0;
 }
 
-static struct rtc_class_ops m41t80_rtc_ops = {
+static const struct rtc_class_ops m41t80_rtc_ops = {
 	.read_time = m41t80_rtc_read_time,
 	.set_time = m41t80_rtc_set_time,
 	.proc = m41t80_rtc_proc,
+	.read_alarm = m41t80_read_alarm,
+	.set_alarm = m41t80_set_alarm,
+	.alarm_irq_enable = m41t80_alarm_irq_enable,
 };
 
 #ifdef CONFIG_PM_SLEEP
···
 			wakeup_source = false;
 		}
 	}
-	if (client->irq > 0 || wakeup_source) {
-		m41t80_rtc_ops.read_alarm = m41t80_read_alarm;
-		m41t80_rtc_ops.set_alarm = m41t80_set_alarm;
-		m41t80_rtc_ops.alarm_irq_enable = m41t80_alarm_irq_enable;
-		/* Enable the wakealarm */
+	if (client->irq > 0 || wakeup_source)
 		device_init_wakeup(&client->dev, true);
-	}
+	else
+		clear_bit(RTC_FEATURE_ALARM, m41t80_data->rtc->features);
 
 	m41t80_data->rtc->ops = &m41t80_rtc_ops;
 	m41t80_data->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;