[PATCH v3 1/3] ARM: at91: fix hanged boot due to early rtc-interrupt

From: Johan Hovold
Date: Wed Oct 16 2013 - 06:00:58 EST

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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@xxxxxxxxx>
---
arch/arm/mach-at91/Makefile | 2 +-
arch/arm/mach-at91/at91sam9g45.c | 2 ++
arch/arm/mach-at91/at91sam9n12.c | 6 ++++
arch/arm/mach-at91/at91sam9rl.c | 2 ++
arch/arm/mach-at91/at91sam9x5.c | 6 ++++
arch/arm/mach-at91/generic.h | 1 +
arch/arm/mach-at91/include/mach/at91sam9n12.h | 5 +++
arch/arm/mach-at91/include/mach/at91sam9x5.h | 5 +++
arch/arm/mach-at91/include/mach/sama5d3.h | 5 +++
arch/arm/mach-at91/sama5d3.c | 6 ++++
arch/arm/mach-at91/sysirq_mask.c | 47 +++++++++++++++++++++++++++
11 files changed, 86 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/mach-at91/sysirq_mask.c

diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index aa33b0f..8879a41 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -2,7 +2,7 @@
# Makefile for the linux kernel.
#

-obj-y := irq.o gpio.o setup.o
+obj-y := irq.o gpio.o setup.o sysirq_mask.o
obj-m :=
obj-n :=
obj- :=
diff --git a/arch/arm/mach-at91/at91sam9g45.c b/arch/arm/mach-at91/at91sam9g45.c
index b9fe138..8d4da6d 100644
--- a/arch/arm/mach-at91/at91sam9g45.c
+++ b/arch/arm/mach-at91/at91sam9g45.c
@@ -379,6 +379,8 @@ static void __init at91sam9g45_initialize(void)
arm_pm_idle = at91sam9_idle;
arm_pm_restart = at91sam9g45_restart;

+ at91_sysirq_mask_rtc(AT91SAM9G45_BASE_RTC);
+
/* Register GPIO subsystem */
at91_gpio_init(at91sam9g45_gpio, 5);
}
diff --git a/arch/arm/mach-at91/at91sam9n12.c b/arch/arm/mach-at91/at91sam9n12.c
index c7d670d..4d6001c 100644
--- a/arch/arm/mach-at91/at91sam9n12.c
+++ b/arch/arm/mach-at91/at91sam9n12.c
@@ -223,7 +223,13 @@ static void __init at91sam9n12_map_io(void)
at91_init_sram(0, AT91SAM9N12_SRAM_BASE, AT91SAM9N12_SRAM_SIZE);
}

+static void __init at91sam9n12_initialize(void)
+{
+ at91_sysirq_mask_rtc(AT91SAM9N12_BASE_RTC);
+}
+
AT91_SOC_START(at91sam9n12)
.map_io = at91sam9n12_map_io,
.register_clocks = at91sam9n12_register_clocks,
+ .init = at91sam9n12_initialize,
AT91_SOC_END
diff --git a/arch/arm/mach-at91/at91sam9rl.c b/arch/arm/mach-at91/at91sam9rl.c
index d4ec0d9..b5a8c9d 100644
--- a/arch/arm/mach-at91/at91sam9rl.c
+++ b/arch/arm/mach-at91/at91sam9rl.c
@@ -294,6 +294,8 @@ static void __init at91sam9rl_initialize(void)
arm_pm_idle = at91sam9_idle;
arm_pm_restart = at91sam9_alt_restart;

+ at91_sysirq_mask_rtc(AT91SAM9RL_BASE_RTC);
+
/* Register GPIO subsystem */
at91_gpio_init(at91sam9rl_gpio, 4);
}
diff --git a/arch/arm/mach-at91/at91sam9x5.c b/arch/arm/mach-at91/at91sam9x5.c
index 916e5a1..e8a2e07 100644
--- a/arch/arm/mach-at91/at91sam9x5.c
+++ b/arch/arm/mach-at91/at91sam9x5.c
@@ -322,6 +322,11 @@ static void __init at91sam9x5_map_io(void)
at91_init_sram(0, AT91SAM9X5_SRAM_BASE, AT91SAM9X5_SRAM_SIZE);
}

+static void __init at91sam9x5_initialize(void)
+{
+ at91_sysirq_mask_rtc(AT91SAM9X5_BASE_RTC);
+}
+
/* --------------------------------------------------------------------
* Interrupt initialization
* -------------------------------------------------------------------- */
@@ -329,4 +334,5 @@ static void __init at91sam9x5_map_io(void)
AT91_SOC_START(at91sam9x5)
.map_io = at91sam9x5_map_io,
.register_clocks = at91sam9x5_register_clocks,
+ .init = at91sam9x5_initialize,
AT91_SOC_END
diff --git a/arch/arm/mach-at91/generic.h b/arch/arm/mach-at91/generic.h
index dc6e2f5..80269bd 100644
--- a/arch/arm/mach-at91/generic.h
+++ b/arch/arm/mach-at91/generic.h
@@ -34,6 +34,7 @@ extern int __init at91_aic_of_init(struct device_node *node,
struct device_node *parent);
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);

/* Timer */
diff --git a/arch/arm/mach-at91/include/mach/at91sam9n12.h b/arch/arm/mach-at91/include/mach/at91sam9n12.h
index d374b87..0151bcf 100644
--- a/arch/arm/mach-at91/include/mach/at91sam9n12.h
+++ b/arch/arm/mach-at91/include/mach/at91sam9n12.h
@@ -49,6 +49,11 @@
#define AT91SAM9N12_BASE_USART3 0xf8028000

/*
+ * System Peripherals
+ */
+#define AT91SAM9N12_BASE_RTC 0xfffffeb0
+
+/*
* Internal Memory.
*/
#define AT91SAM9N12_SRAM_BASE 0x00300000 /* Internal SRAM base address */
diff --git a/arch/arm/mach-at91/include/mach/at91sam9x5.h b/arch/arm/mach-at91/include/mach/at91sam9x5.h
index c75ee19..2fc76c4 100644
--- a/arch/arm/mach-at91/include/mach/at91sam9x5.h
+++ b/arch/arm/mach-at91/include/mach/at91sam9x5.h
@@ -55,6 +55,11 @@
#define AT91SAM9X5_BASE_USART2 0xf8024000

/*
+ * System Peripherals
+ */
+#define AT91SAM9X5_BASE_RTC 0xfffffeb0
+
+/*
* Internal Memory.
*/
#define AT91SAM9X5_SRAM_BASE 0x00300000 /* Internal SRAM base address */
diff --git a/arch/arm/mach-at91/include/mach/sama5d3.h b/arch/arm/mach-at91/include/mach/sama5d3.h
index 31096a8..25613d8 100644
--- a/arch/arm/mach-at91/include/mach/sama5d3.h
+++ b/arch/arm/mach-at91/include/mach/sama5d3.h
@@ -73,6 +73,11 @@
#define SAMA5D3_BASE_USART3 0xf8024000

/*
+ * System Peripherals
+ */
+#define SAMA5D3_BASE_RTC 0xfffffeb0
+
+/*
* Internal Memory
*/
#define SAMA5D3_SRAM_BASE 0x00300000 /* Internal SRAM base address */
diff --git a/arch/arm/mach-at91/sama5d3.c b/arch/arm/mach-at91/sama5d3.c
index 4012797..3ea8642 100644
--- a/arch/arm/mach-at91/sama5d3.c
+++ b/arch/arm/mach-at91/sama5d3.c
@@ -371,7 +371,13 @@ static void __init sama5d3_map_io(void)
at91_init_sram(0, SAMA5D3_SRAM_BASE, SAMA5D3_SRAM_SIZE);
}

+static void __init sama5d3_initialize(void)
+{
+ at91_sysirq_mask_rtc(SAMA5D3_BASE_RTC);
+}
+
AT91_SOC_START(sama5d3)
.map_io = sama5d3_map_io,
.register_clocks = sama5d3_register_clocks,
+ .init = sama5d3_initialize,
AT91_SOC_END
diff --git a/arch/arm/mach-at91/sysirq_mask.c b/arch/arm/mach-at91/sysirq_mask.c
new file mode 100644
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@xxxxxxxxx>
+ *
+ * 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);
+}
--
1.8.4

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Next message: Johan Hovold: "[PATCH v3 0/3] ARM: at91: fix hanged boot"
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Next in thread: Johan Hovold: "[PATCH v3 3/3] ARM: at91/rtc: disable interrupts at shutdown"
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