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Date:   Mon, 6 May 2019 11:27:52 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Anson Huang <anson.huang@nxp.com>
Cc:     "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "wim@linux-watchdog.org" <wim@linux-watchdog.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        Aisheng Dong <aisheng.dong@nxp.com>,
        "ulf.hansson@linaro.org" <ulf.hansson@linaro.org>,
        "sboyd@kernel.org" <sboyd@kernel.org>,
        Daniel Baluta <daniel.baluta@nxp.com>,
        Peng Fan <peng.fan@nxp.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH V3 3/3] watchdog: imx_sc: Add pretimeout support
Message-ID: <20190506182752.GA358@roeck-us.net>
References: <1557022189-10993-1-git-send-email-Anson.Huang@nxp.com>
 <1557022189-10993-3-git-send-email-Anson.Huang@nxp.com>
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On Sun, May 05, 2019 at 02:15:00AM +0000, Anson Huang wrote:
> i.MX system controller watchdog can support pretimeout IRQ
> via general SCU MU IRQ, it depends on IMX_SCU and driver MUST
> be probed after SCU IPC ready, then enable corresponding SCU
> IRQ group and register SCU IRQ notifier, when watchdog pretimeout
> IRQ fires, SCU MU IRQ will be handled and watchdog pretimeout
> notifier will be called to handle the event.
> 
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> No change.
> ---
>  drivers/watchdog/Kconfig      |   1 +
>  drivers/watchdog/imx_sc_wdt.c | 114 ++++++++++++++++++++++++++++++++++--------
>  2 files changed, 95 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index e19960a..dbc74e1 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -710,6 +710,7 @@ config IMX2_WDT
>  config IMX_SC_WDT
>  	tristate "IMX SC Watchdog"
>  	depends on HAVE_ARM_SMCCC
> +	depends on IMX_SCU
>  	select WATCHDOG_CORE
>  	help
>  	  This is the driver for the system controller watchdog
> diff --git a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c
> index 49848b6..d8493a3 100644
> --- a/drivers/watchdog/imx_sc_wdt.c
> +++ b/drivers/watchdog/imx_sc_wdt.c
> @@ -4,6 +4,7 @@
>   */
>  
>  #include <linux/arm-smccc.h>
> +#include <linux/firmware/imx/sci.h>
>  #include <linux/io.h>
>  #include <linux/init.h>
>  #include <linux/kernel.h>
> @@ -33,11 +34,19 @@
>  
>  #define SC_TIMER_WDOG_ACTION_PARTITION	0
>  
> +#define SC_IRQ_WDOG			1
> +#define SC_IRQ_GROUP_WDOG		1
> +
>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  module_param(nowayout, bool, 0000);
>  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
>  		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>  
> +struct imx_sc_wdt_device {
> +	struct watchdog_device wdd;
> +	struct notifier_block wdt_notifier;
> +};
> +
>  static int imx_sc_wdt_ping(struct watchdog_device *wdog)
>  {
>  	struct arm_smccc_res res;
> @@ -85,24 +94,66 @@ static int imx_sc_wdt_set_timeout(struct watchdog_device *wdog,
>  	return res.a0 ? -EACCES : 0;
>  }
>  
> +static int imx_sc_wdt_set_pretimeout(struct watchdog_device *wdog,
> +				     unsigned int pretimeout)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_PRETIME_WDOG,
> +		      pretimeout * 1000, 0, 0, 0, 0, 0, &res);
> +	if (res.a0)
> +		return -EACCES;
> +
> +	wdog->pretimeout = pretimeout;
> +
> +	return 0;
> +}
> +
> +static int imx_sc_wdt_notify(struct notifier_block *nb,
> +			     unsigned long event, void *group)
> +{
> +	struct imx_sc_wdt_device *imx_sc_wdd =
> +				 container_of(nb,
> +					      struct imx_sc_wdt_device,
> +					      wdt_notifier);
> +
> +	if (event & SC_IRQ_WDOG &&
> +	    *(u8 *)group == SC_IRQ_GROUP_WDOG)
> +		watchdog_notify_pretimeout(&imx_sc_wdd->wdd);
> +
> +	return 0;
> +}
> +
> +static void imx_sc_wdt_action(void *data)
> +{
> +	struct notifier_block *wdt_notifier = data;
> +
> +	imx_scu_irq_unregister_notifier(wdt_notifier);
> +	imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> +				 SC_IRQ_WDOG,
> +				 false);
> +}
> +
>  static const struct watchdog_ops imx_sc_wdt_ops = {
>  	.owner = THIS_MODULE,
>  	.start = imx_sc_wdt_start,
>  	.stop  = imx_sc_wdt_stop,
>  	.ping  = imx_sc_wdt_ping,
>  	.set_timeout = imx_sc_wdt_set_timeout,
> +	.set_pretimeout = imx_sc_wdt_set_pretimeout,
>  };
>  
> -static const struct watchdog_info imx_sc_wdt_info = {
> +static struct watchdog_info imx_sc_wdt_info = {
>  	.identity	= "i.MX SC watchdog timer",
>  	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> -			  WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT,
> +			  WDIOF_MAGICCLOSE,
>  };
>  
>  static int imx_sc_wdt_probe(struct platform_device *pdev)
>  {
> +	struct imx_sc_wdt_device *imx_sc_wdd;
> +	struct watchdog_device *wdog;
>  	struct device *dev = &pdev->dev;
> -	struct watchdog_device *imx_sc_wdd;
>  	int ret;
>  
>  	imx_sc_wdd = devm_kzalloc(dev, sizeof(*imx_sc_wdd), GFP_KERNEL);
> @@ -111,42 +162,65 @@ static int imx_sc_wdt_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, imx_sc_wdd);
>  
> -	imx_sc_wdd->info = &imx_sc_wdt_info;
> -	imx_sc_wdd->ops = &imx_sc_wdt_ops;
> -	imx_sc_wdd->min_timeout = 1;
> -	imx_sc_wdd->max_timeout = MAX_TIMEOUT;
> -	imx_sc_wdd->parent = dev;
> -	imx_sc_wdd->timeout = DEFAULT_TIMEOUT;
> +	wdog = &imx_sc_wdd->wdd;
> +	wdog->info = &imx_sc_wdt_info;
> +	wdog->ops = &imx_sc_wdt_ops;
> +	wdog->min_timeout = 1;
> +	wdog->max_timeout = MAX_TIMEOUT;
> +	wdog->parent = dev;
> +	wdog->timeout = DEFAULT_TIMEOUT;
>  
> -	watchdog_init_timeout(imx_sc_wdd, 0, dev);
> -	watchdog_stop_on_reboot(imx_sc_wdd);
> -	watchdog_stop_on_unregister(imx_sc_wdd);
> +	watchdog_init_timeout(wdog, 0, dev);
> +	watchdog_stop_on_reboot(wdog);
> +	watchdog_stop_on_unregister(wdog);
>  
> -	ret = devm_watchdog_register_device(dev, imx_sc_wdd);
> +	ret = devm_watchdog_register_device(dev, wdog);
>  	if (ret) {
>  		dev_err(dev, "Failed to register watchdog device\n");
>  		return ret;
>  	}
>  
> -	return 0;
> +	ret = imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> +				       SC_IRQ_WDOG,
> +				       true);
> +	if (ret) {
> +		dev_warn(dev, "Enable irq failed, pretimeout NOT supported\n");
> +		return 0;
> +	}
> +
> +	imx_sc_wdd->wdt_notifier.notifier_call = imx_sc_wdt_notify;
> +	ret = imx_scu_irq_register_notifier(&imx_sc_wdd->wdt_notifier);
> +	if (ret) {
> +		imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> +					 SC_IRQ_WDOG,
> +					 false);
> +		dev_warn(dev,
> +			 "Register irq notifier failed, pretimeout NOT supported\n");
> +		return 0;
> +	}
> +
> +	imx_sc_wdt_info.options |= WDIOF_PRETIMEOUT;
> +	ret = devm_add_action(dev, imx_sc_wdt_action,
> +			      &imx_sc_wdd->wdt_notifier);

This needs devm_add_action_or_reset() because otherwise the notifier would
not be removed, and the interrupt group would not be disabled.

> +	return ret;

This should not return an error. Accepting that the notifier can not be
registered and that the irq group can not be enabled but bailing out if
devm_add_action() fails is inconsistent.

Guenter

>  }
>  
>  static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
>  {
> -	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> +	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
>  
> -	if (watchdog_active(imx_sc_wdd))
> -		imx_sc_wdt_stop(imx_sc_wdd);
> +	if (watchdog_active(&imx_sc_wdd->wdd))
> +		imx_sc_wdt_stop(&imx_sc_wdd->wdd);
>  
>  	return 0;
>  }
>  
>  static int __maybe_unused imx_sc_wdt_resume(struct device *dev)
>  {
> -	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> +	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
>  
> -	if (watchdog_active(imx_sc_wdd))
> -		imx_sc_wdt_start(imx_sc_wdd);
> +	if (watchdog_active(&imx_sc_wdd->wdd))
> +		imx_sc_wdt_start(&imx_sc_wdd->wdd);
>  
>  	return 0;
>  }
> -- 
> 2.7.4
>