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

76 lines
2.0 KiB
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 <mach/at91_rtt.h>
#include "generic.h"
#define AT91_RTC_IDR 0x24 /* Interrupt Disable Register */
#define AT91_RTC_IMR 0x28 /* Interrupt Mask Register */
#define AT91_RTC_IRQ_MASK 0x1f /* Available IRQs mask */
void __init at91_sysirq_mask_rtc(u32 rtc_base)
{
void __iomem *base;
base = ioremap(rtc_base, 64);
if (!base)
return;
/*
* sam9x5 SoCs have the following errata:
* "RTC: Interrupt Mask Register cannot be used
* Interrupt Mask Register read always returns 0."
*
* Hence we're not relying on IMR values to disable
* interrupts.
*/
writel_relaxed(AT91_RTC_IRQ_MASK, base + AT91_RTC_IDR);
(void)readl_relaxed(base + AT91_RTC_IMR); /* flush */
iounmap(base);
}
void __init at91_sysirq_mask_rtt(u32 rtt_base)
{
void __iomem *base;
void __iomem *reg;
u32 mode;
base = ioremap(rtt_base, 16);
if (!base)
return;
reg = base + AT91_RTT_MR;
mode = readl_relaxed(reg);
if (mode & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)) {
pr_info("AT91: Disabling rtt irq\n");
mode &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
writel_relaxed(mode, reg);
(void)readl_relaxed(reg); /* flush */
}
iounmap(base);
}