linux-kernel - [PATCH v3 3/3] ARM: at91/rtc: disable interrupts at shutdown

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Date:	Wed, 16 Oct 2013 11:56:16 +0200
From:	Johan Hovold <jhovold@...il.com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>
Cc:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Andrew Victor <linux@...im.org.za>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	rtc-linux@...glegroups.com, Johan Hovold <jhovold@...il.com>
Subject: [PATCH v3 3/3] ARM: at91/rtc: disable interrupts at shutdown

Make sure RTC-interrupts are disabled at shutdown.

As the RTC is generally powered by backup power (VDDBU), its interrupts
are not disabled on wake-up, user, watchdog or software reset. This
could cause troubles on other systems (e.g. older kernels) if an
interrupt occurs before a handler has been installed at next boot.

Let us be well-behaved and disable them on clean shutdowns at least (as
do the RTT-based rtc-at91sam9 driver).

Signed-off-by: Johan Hovold <jhovold@...il.com>
---
 drivers/rtc/rtc-at91rm9200.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index 7418926..ea088e9 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -442,6 +442,14 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void at91_rtc_shutdown(struct platform_device *pdev)
+{
+	/* Disable all interrupts */
+	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
+					AT91_RTC_SECEV | AT91_RTC_TIMEV |
+					AT91_RTC_CALEV);
+}
+
 #ifdef CONFIG_PM_SLEEP
 
 /* AT91RM9200 RTC Power management control */
@@ -480,6 +488,7 @@ static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
 
 static struct platform_driver at91_rtc_driver = {
 	.remove		= __exit_p(at91_rtc_remove),
+	.shutdown	= at91_rtc_shutdown,
 	.driver		= {
 		.name	= "at91_rtc",
 		.owner	= THIS_MODULE,
-- 
1.8.4

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