linux-kernel - Re: [PATCH v2 2/3] watchdog: mpc8xxx: provide boot status

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Message-ID: <20180914173541.GG26861@roeck-us.net>
Date:   Fri, 14 Sep 2018 10:35:41 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Radu Rendec <radu.rendec@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/3] watchdog: mpc8xxx: provide boot status

On Fri, Sep 14, 2018 at 01:32:01PM +0000, Christophe Leroy wrote:
> mpc8xxx watchdog driver supports the following platforms:
> - mpc8xx
> - mpc83xx
> - mpc86xx
> 
> Those three platforms have a 32 bits register which provides the
> reason of the last boot, including whether it was caused by the
> watchdog.
> 
> mpc8xx: Register RSR, bit SWRS (bit 3)
> mpc83xx: Register RSR, bit SWRS (bit 28)
> mpc86xx: Register RSTRSCR, bit WDT_RR (bit 11)
> 
> This patch maps the register as defined in the device tree and updates
> wdt.bootstatus based on the value of the watchdog related bit. Then
> the information can be retrieved via the WDIOC_GETBOOTSTATUS ioctl.
> 
> Hereunder is an example of devicetree for mpc8xx,
> the Reset Status Register being at offset 0x288:
> 
> 		WDT: watchdog@0 {
> 			compatible = "fsl,mpc823-wdt";
> 			reg = <0x0 0x10 0x288 0x4>;
> 		};
> 
> On the mpc83xx, RSR is at offset 0x910
> On the mpc86xx, RSTRSCR is at offset 0xe0094
> 
> Suggested-by: Radu Rendec <radu.rendec@...il.com>
> Tested-by: Christophe Leroy <christophe.leroy@....fr> # On mpc885
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  drivers/watchdog/mpc8xxx_wdt.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/watchdog/mpc8xxx_wdt.c b/drivers/watchdog/mpc8xxx_wdt.c
> index 1dcf5f10cdd9..4a4700458b17 100644
> --- a/drivers/watchdog/mpc8xxx_wdt.c
> +++ b/drivers/watchdog/mpc8xxx_wdt.c
> @@ -47,6 +47,7 @@ struct mpc8xxx_wdt {
>  struct mpc8xxx_wdt_type {
>  	int prescaler;
>  	bool hw_enabled;
> +	u32 rsr_mask;
>  };
>  
>  struct mpc8xxx_wdt_ddata {
> @@ -136,6 +137,7 @@ static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
>  	u32 freq = fsl_get_sys_freq();
>  	bool enabled;
>  	struct device *dev = &ofdev->dev;
> +	u32 __iomem *rsr = NULL;
>  
>  	wdt_type = of_device_get_match_data(dev);
>  	if (!wdt_type)
> @@ -159,6 +161,21 @@ static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
>  		return -ENODEV;
>  	}
>  
> +	res = platform_get_resource(ofdev, IORESOURCE_MEM, 1);
> +	if (res)
> +		rsr = ioremap(res->start, resource_size(res));
> +	if (rsr) {

This if() can be inside the first if(), and it should be something like

	if (res) {
		rsr = ioremap(res->start, resource_size(res));
		if (!rsr) {
			dev_err(...);
			return -ENOMEM;
		}
		...
	}

... because _if_ the resource is provided in dt it should be valid.

Thanks,
Guenter

> +		bool status = in_be32(rsr) & wdt_type->rsr_mask;
> +
> +		ddata->wdd.bootstatus = status ? WDIOF_CARDRESET : 0;
> +		 /* clear reset status bits related to watchdog timer */
> +		out_be32(rsr, wdt_type->rsr_mask);
> +		iounmap(rsr);
> +
> +		dev_info(dev, "Last boot was %scaused by watchdog\n",
> +			 status ? "" : "not ");
> +	}
> +
>  	spin_lock_init(&ddata->lock);
>  
>  	ddata->wdd.info = &mpc8xxx_wdt_info,
> @@ -216,6 +233,7 @@ static const struct of_device_id mpc8xxx_wdt_match[] = {
>  		.compatible = "mpc83xx_wdt",
>  		.data = &(struct mpc8xxx_wdt_type) {
>  			.prescaler = 0x10000,
> +			.rsr_mask = BIT(3), /* RSR Bit SWRS */
>  		},
>  	},
>  	{
> @@ -223,6 +241,7 @@ static const struct of_device_id mpc8xxx_wdt_match[] = {
>  		.data = &(struct mpc8xxx_wdt_type) {
>  			.prescaler = 0x10000,
>  			.hw_enabled = true,
> +			.rsr_mask = BIT(20), /* RSTRSCR Bit WDT_RR */
>  		},
>  	},
>  	{
> @@ -230,6 +249,7 @@ static const struct of_device_id mpc8xxx_wdt_match[] = {
>  		.data = &(struct mpc8xxx_wdt_type) {
>  			.prescaler = 0x800,
>  			.hw_enabled = true,
> +			.rsr_mask = BIT(28), /* RSR Bit SWRS */
>  		},
>  	},
>  	{},
> -- 
> 2.13.3
>