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

[Nicolas Ferre <nicolas.ferre@atmel.com>]

On 16/10/2013 11:56, Johan Hovold :
> 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>

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

and added to the at91-3.13-fixes-non-critical branch with the "stable" tag:
Cc: stable@vger.kernel.org # 3.11.x

Thanks a lot Johan.

> ---
>   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@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);
> +}
>


-- 
Nicolas Ferre