ARM: at91: fix hanged boot due to early rtc-interrupt

[cascardo/linux.git] / arch / arm / mach-at91 / sysirq_mask.c

diff --git a/arch/arm/mach-at91/sysirq_mask.c b/arch/arm/mach-at91/sysirq_mask.c
new file mode 100644 (file)
index 0000000..ee3e22c
--- /dev/null
+++ b/arch/arm/mach-at91/sysirq_mask.c
@@ -0,0 +1,47 @@
+/*
+ * sysirq_mask.c - System-interrupt masking
+ *
+ * Copyright (C) 2013 Johan Hovold <jhovold@gmail.com>
+ *
+ * Functions to disable system interrupts from backup-powered peripherals.
+ *
+ * The RTC and RTT-peripherals are generally powered by backup power (VDDBU)
+ * and are not reset on wake-up, user, watchdog or software reset. This means
+ * that their interrupts may be enabled during early boot (e.g. after a user
+ * reset).
+ *
+ * As the RTC and RTT share the system-interrupt line with the PIT, an
+ * interrupt occurring before a handler has been installed would lead to the
+ * system interrupt being disabled and prevent the system from booting.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/io.h>
+
+#include "generic.h"
+
+#define AT91_RTC_IDR   0x24    /* Interrupt Disable Register */
+#define AT91_RTC_IMR   0x28    /* Interrupt Mask Register */
+
+void __init at91_sysirq_mask_rtc(u32 rtc_base)
+{
+       void __iomem *base;
+       u32 mask;
+
+       base = ioremap(rtc_base, 64);
+       if (!base)
+               return;
+
+       mask = readl_relaxed(base + AT91_RTC_IMR);
+       if (mask) {
+               pr_info("AT91: Disabling rtc irq\n");
+               writel_relaxed(mask, base + AT91_RTC_IDR);
+               (void)readl_relaxed(base + AT91_RTC_IMR);       /* flush */
+       }
+
+       iounmap(base);
+}