linux-kernel - Re: [PATCH] watchdog: s3c2410_wdt: Report when the watchdog reset the system

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Message-id: <42011482.56GYn1upCz@amdc1227>
Date:	Thu, 05 Dec 2013 17:21:47 +0100
From:	Tomasz Figa <t.figa@...sung.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Wim Van Sebroeck <wim@...ana.be>,
	Guenter Roeck <linux@...ck-us.net>,
	Leela Krishna Amudala <l.krishna@...sung.com>,
	Olof Johansson <olof@...om.net>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Ben Dooks <ben-linux@...ff.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-watchdog@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: s3c2410_wdt: Report when the watchdog reset the
 system

Hi Doug,

Please see my comments inline.

On Monday 02 of December 2013 10:14:41 Doug Anderson wrote:
> A good watchdog driver is supposed to report when it was responsible
> for resetting the system.  Implement this for the s3c2410, at least on
> exynos5250 and exynos5420 where we already have a pointer to the PMU
> registers to read the information.
> 
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> ---
> This patch is based atop Leela Krishna's recent series that ends with
> (ARM: dts: update watchdog device nodes for Exynos5250 and Exynos5420)
> AKA <https://patchwork.kernel.org/patch/3251861/>.
> 
>  drivers/watchdog/s3c2410_wdt.c | 42 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 47f4dcf..2c87d37 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -62,9 +62,13 @@
>  #define CONFIG_S3C2410_WATCHDOG_ATBOOT		(0)
>  #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME	(15)
>  
> +#define RST_STAT_REG_OFFSET		0x0404

IMHO this should be namespaced, at least with EXYNOS5 prefix. The two
registers below should be as well, but I missed this in the patch adding
them.

>  #define WDT_DISABLE_REG_OFFSET		0x0408
>  #define WDT_MASK_RESET_REG_OFFSET	0x040c
>  #define QUIRK_NEEDS_PMU_CONFIG		(1 << 0)
> +#define QUIRK_HAS_RST_STAT		(1 << 1)
> +#define QUIRKS_NEED_PMUREG		(QUIRK_NEEDS_PMU_CONFIG | \
> +					 QUIRK_HAS_RST_STAT)
>  
>  static bool nowayout	= WATCHDOG_NOWAYOUT;
>  static int tmr_margin;
> @@ -98,6 +102,9 @@ MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");
>   * timer reset functionality.
>   * @mask_bit: Bit number for the watchdog timer in the disable register and the
>   * mask reset register.
> + * @rst_stat_reg: Offset in pmureg for the register that has the reset status.
> + * @rst_stat_bit: Bit number in the rst_stat register indicating a watchdog
> + * reset.
>   * @quirks: A bitfield of quirks.
>   */
>  
> @@ -105,6 +112,8 @@ struct s3c2410_wdt_variant {
>  	int disable_reg;
>  	int mask_reset_reg;
>  	int mask_bit;
> +	int rst_stat_reg;
> +	int rst_stat_bit;
>  	u32 quirks;
>  };
>  
> @@ -131,14 +140,20 @@ static const struct s3c2410_wdt_variant drv_data_exynos5250  = {
>  	.disable_reg = WDT_DISABLE_REG_OFFSET,
>  	.mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
>  	.mask_bit = 20,
> -	.quirks = QUIRK_NEEDS_PMU_CONFIG
> +	.rst_stat_reg = RST_STAT_REG_OFFSET,
> +	.rst_stat_bit = 20,
> +	.quirks = QUIRK_NEEDS_PMU_CONFIG |
> +		QUIRK_HAS_RST_STAT,
>  };
>  
>  static const struct s3c2410_wdt_variant drv_data_exynos5420 = {
>  	.disable_reg = WDT_DISABLE_REG_OFFSET,
>  	.mask_reset_reg = WDT_MASK_RESET_REG_OFFSET,
>  	.mask_bit = 0,
> -	.quirks = QUIRK_NEEDS_PMU_CONFIG
> +	.rst_stat_reg = RST_STAT_REG_OFFSET,
> +	.rst_stat_bit = 9,
> +	.quirks = QUIRK_NEEDS_PMU_CONFIG |
> +		QUIRK_HAS_RST_STAT,
>  };
>  
>  static const struct of_device_id s3c2410_wdt_match[] = {
> @@ -423,6 +438,25 @@ static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
>  }
>  #endif
>  
> +static inline unsigned int s3c2410wdt_get_bootstatus(struct s3c2410_wdt *wdt)
> +{
> +	unsigned int bootstatus = 0;
> +	int ret;
> +
> +	if (wdt->drv_data->quirks & QUIRK_HAS_RST_STAT) {

nit: I guess it's just a matter of taste, but to reduce code indentation
you could inverse the check and simply return 0 here.

Best regards,
Tomasz

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