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

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

diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index 3b0a9538093c168cb4cd80f4ff559b0458d0dfb3..e0fda04e6aa1fb4ecbff2f58b4798cd5bdf38060 100644 (file)
--- 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 474ee04d24b93729bdf32e2e4d64a7db0ea9bed8..ff662af77feeba9ecb1f5355e8f9ab435a4b142a 100644 (file)
--- a/arch/arm/mach-at91/at91sam9g45.c
+++ b/arch/arm/mach-at91/at91sam9g45.c
@@ -377,6 +377,8 @@ 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 c7d670d118025eaf71a4dd145d0d3a33d300a415..4d6001c355f5cebae330defde5f20df4e58a405f 100644 (file)
--- 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 d4ec0d9a9872660e22f2e3c95fc2e8c154cf38e6..b5a8c9d81bc8a3a0c2989d9fa8da78271ffd2f56 100644 (file)
--- 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 916e5a1429171bd39835da54b02fa444b1941905..e8a2e075a1b888262077e46457774679d51776e9 100644 (file)
--- 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 dc6e2f5f804dcc26471daf42ecd4ef1e454656fa..80269bda0dd72cc652e26853fd2a06008b0e1cbb 100644 (file)
--- 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 d374b87c045914348349ef721feadd9e87170921..0151bcf6163cddd349c5d6f8e88198c3831bf3b9 100644 (file)
--- a/arch/arm/mach-at91/include/mach/at91sam9n12.h
+++ b/arch/arm/mach-at91/include/mach/at91sam9n12.h
@@ -48,6 +48,11 @@
 #define AT91SAM9N12_BASE_USART2        0xf8024000
 #define AT91SAM9N12_BASE_USART3        0xf8028000
 
+/*
+ * System Peripherals
+ */
+#define AT91SAM9N12_BASE_RTC   0xfffffeb0
+
 /*
  * Internal Memory.
  */

diff --git a/arch/arm/mach-at91/include/mach/at91sam9x5.h b/arch/arm/mach-at91/include/mach/at91sam9x5.h
index c75ee19b58d3de69c79e81e312c416fbd6071ef0..2fc76c49e97cf4152c9427f62a39bad4e71b51d4 100644 (file)
--- a/arch/arm/mach-at91/include/mach/at91sam9x5.h
+++ b/arch/arm/mach-at91/include/mach/at91sam9x5.h
@@ -54,6 +54,11 @@
 #define AT91SAM9X5_BASE_USART1 0xf8020000
 #define AT91SAM9X5_BASE_USART2 0xf8024000
 
+/*
+ * System Peripherals
+ */
+#define AT91SAM9X5_BASE_RTC    0xfffffeb0
+
 /*
  * Internal Memory.
  */

diff --git a/arch/arm/mach-at91/include/mach/sama5d3.h b/arch/arm/mach-at91/include/mach/sama5d3.h
index 31096a8aaf1d507287d62f6ef8250096f7ee09ea..25613d8c6dcd6687dd0b896883aedbe52f3461c6 100644 (file)
--- a/arch/arm/mach-at91/include/mach/sama5d3.h
+++ b/arch/arm/mach-at91/include/mach/sama5d3.h
@@ -72,6 +72,11 @@
 #define SAMA5D3_BASE_USART2    0xf8020000
 #define SAMA5D3_BASE_USART3    0xf8024000
 
+/*
+ * System Peripherals
+ */
+#define SAMA5D3_BASE_RTC       0xfffffeb0
+
 /*
  * Internal Memory
  */

diff --git a/arch/arm/mach-at91/sama5d3.c b/arch/arm/mach-at91/sama5d3.c
index 401279715ab19b8ec694463d442af33b93aff827..3ea86428ee0964f11d0955a90d0348626e68da58 100644 (file)
--- 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 (file)
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@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);
+}