linux-vybrid_public/arch/arm/mach-at91/sysirq_mask.c

/*
 * 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);
}