rtc-at91rm9200: use shadow IMR on at91sam9x5

Add support for the at91sam9x5-family which must use the shadow interrupt mask due to a hardware issue (causing RTC_IMR to always be zero). Signed-off-by: Johan Hovold <jhovold@gmail.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: Robert Nelson <Robert.Nelson@digikey.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: jhovold

Documentation/devicetree/bindings/rtc/atmel,at91rm9200-rtc.txt

@@ -1,7 +1,7 @@
 Atmel AT91RM9200 Real Time Clock
 
 Required properties:
-- compatible: should be: "atmel,at91rm9200-rtc"
+- compatible: should be: "atmel,at91rm9200-rtc" or "atmel,at91sam9x5-rtc"
 - reg: physical base address of the controller and length of memory mapped
  region.
 - interrupts: rtc alarm/event interrupt

drivers/rtc/rtc-at91rm9200.c

@@ -309,11 +309,18 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
 static const struct at91_rtc_config at91rm9200_config = {
 };
 
+static const struct at91_rtc_config at91sam9x5_config = {
+.use_shadow_imr= true,
+};
+
 #ifdef CONFIG_OF
 static const struct of_device_id at91_rtc_dt_ids[] = {
 {
 .compatible = "atmel,at91rm9200-rtc",
 .data = &at91rm9200_config,
+}, {
+.compatible = "atmel,at91sam9x5-rtc",
+.data = &at91sam9x5_config,
 }, {
 /* sentinel */
 }