6de714c21a
Make sure the RTC-interrupts are masked at boot by adding a new helper function to be used at SOC-init. This fixes hanged boot on all AT91 SOCs with an RTC (but RM9200), for example, after a reset during an RTC-update or if an RTC-alarm goes off after shutdown (e.g. when using RTC wakeup). The RTC and RTT-peripherals are powered by backup power (VDDBU) (on all AT91 SOCs but RM9200) and are not reset on wake-up, user, watchdog or software reset. This means that their interrupts may be enabled during early boot if, for example, they where not disabled during a previous shutdown (e.g. due to a buggy driver or a non-clean shutdown such as a user reset). Furthermore, an RTC or RTT-alarm may also be active. The RTC and RTT-interrupts use the shared system-interrupt line, which is also used by the PIT, and if an interrupt occurs before a handler (e.g. RTC-driver) has been installed this leads to the system interrupt being disabled and prevents the system from booting. Note that when boot hangs due to an early RTC or RTT-interrupt, the only way to get the system to start again is to remove the backup power (e.g. battery) or to disable the interrupt manually from the bootloader. In particular, a user reset is not sufficient. Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Cc: stable@vger.kernel.org # 3.11.x
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/*
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* sysirq_mask.c - System-interrupt masking
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*
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* Copyright (C) 2013 Johan Hovold <jhovold@gmail.com>
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*
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* Functions to disable system interrupts from backup-powered peripherals.
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*
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* The RTC and RTT-peripherals are generally powered by backup power (VDDBU)
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* and are not reset on wake-up, user, watchdog or software reset. This means
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* that their interrupts may be enabled during early boot (e.g. after a user
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* reset).
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*
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* As the RTC and RTT share the system-interrupt line with the PIT, an
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* interrupt occurring before a handler has been installed would lead to the
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* system interrupt being disabled and prevent the system from booting.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/io.h>
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#include "generic.h"
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#define AT91_RTC_IDR 0x24 /* Interrupt Disable Register */
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#define AT91_RTC_IMR 0x28 /* Interrupt Mask Register */
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void __init at91_sysirq_mask_rtc(u32 rtc_base)
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{
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void __iomem *base;
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u32 mask;
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base = ioremap(rtc_base, 64);
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if (!base)
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return;
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mask = readl_relaxed(base + AT91_RTC_IMR);
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if (mask) {
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pr_info("AT91: Disabling rtc irq\n");
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writel_relaxed(mask, base + AT91_RTC_IDR);
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(void)readl_relaxed(base + AT91_RTC_IMR); /* flush */
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}
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iounmap(base);
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}
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