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

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Make sure the RTT-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 RTT, for example, if an
RTT-alarm goes off after a non-clean 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
This commit is contained in:
Johan Hovold 2013-10-16 11:56:15 +02:00 committed by Nicolas Ferre
parent 6de714c21a
commit 94c4c79f2f
7 changed files with 34 additions and 0 deletions
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2
arch/arm/mach-at91/at91sam9260.c
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@ -349,6 +349,8 @@ static void __init at91sam9260_initialize(void)
arm_pm_idle = at91sam9_idle;
arm_pm_restart = at91sam9_alt_restart;
at91_sysirq_mask_rtt(AT91SAM9260_BASE_RTT);
/* Register GPIO subsystem */
at91_gpio_init(at91sam9260_gpio, 3);
}

2
arch/arm/mach-at91/at91sam9261.c
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@ -291,6 +291,8 @@ static void __init at91sam9261_initialize(void)
arm_pm_idle = at91sam9_idle;
arm_pm_restart = at91sam9_alt_restart;
at91_sysirq_mask_rtt(AT91SAM9261_BASE_RTT);
/* Register GPIO subsystem */
at91_gpio_init(at91sam9261_gpio, 3);
}

3
arch/arm/mach-at91/at91sam9263.c
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@ -328,6 +328,9 @@ static void __init at91sam9263_initialize(void)
arm_pm_idle = at91sam9_idle;
arm_pm_restart = at91sam9_alt_restart;
at91_sysirq_mask_rtt(AT91SAM9263_BASE_RTT0);
at91_sysirq_mask_rtt(AT91SAM9263_BASE_RTT1);
/* Register GPIO subsystem */
at91_gpio_init(at91sam9263_gpio, 5);
}

1
arch/arm/mach-at91/at91sam9g45.c
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@ -378,6 +378,7 @@ static void __init at91sam9g45_initialize(void)
arm_pm_restart = at91sam9g45_restart;
at91_sysirq_mask_rtc(AT91SAM9G45_BASE_RTC);
at91_sysirq_mask_rtt(AT91SAM9G45_BASE_RTT);
/* Register GPIO subsystem */
at91_gpio_init(at91sam9g45_gpio, 5);

1
arch/arm/mach-at91/at91sam9rl.c
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@ -295,6 +295,7 @@ static void __init at91sam9rl_initialize(void)
arm_pm_restart = at91sam9_alt_restart;
at91_sysirq_mask_rtc(AT91SAM9RL_BASE_RTC);
at91_sysirq_mask_rtt(AT91SAM9RL_BASE_RTT);
/* Register GPIO subsystem */
at91_gpio_init(at91sam9rl_gpio, 4);

1
arch/arm/mach-at91/generic.h
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@ -35,6 +35,7 @@ extern int __init at91_aic_of_init(struct device_node *node,
extern int __init at91_aic5_of_init(struct device_node *node,
struct device_node *parent);
extern void __init at91_sysirq_mask_rtc(u32 rtc_base);
extern void __init at91_sysirq_mask_rtt(u32 rtt_base);
/* Timer */

24
arch/arm/mach-at91/sysirq_mask.c
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@ -21,6 +21,7 @@
*/
#include <linux/io.h>
#include <mach/at91_rtt.h>
#include "generic.h"
@ -45,3 +46,26 @@ void __init at91_sysirq_mask_rtc(u32 rtc_base)
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);
}