RE: [PATCH V3 3/3] watchdog: imx_sc: Add pretimeout support

[Anson Huang <anson.huang@nxp.com>]

Hi, Guenter

> -----Original Message-----
> From: Guenter Roeck [mailto:groeck7@gmail.com] On Behalf Of Guenter
> Roeck
> Sent: Tuesday, May 7, 2019 2:28 AM
> To: Anson Huang <anson.huang@nxp.com>
> Cc: robh+dt@kernel.org; mark.rutland@arm.com; wim@linux-watchdog.org;
> shawnguo@kernel.org; s.hauer@pengutronix.de; kernel@pengutronix.de;
> festevam@gmail.com; Aisheng Dong <aisheng.dong@nxp.com>;
> ulf.hansson@linaro.org; sboyd@kernel.org; Daniel Baluta
> <daniel.baluta@nxp.com>; Peng Fan <peng.fan@nxp.com>;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> watchdog@vger.kernel.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
> 
> 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.

Right, fix it in V4.

> 
> > +	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.
> 

Agreed, the pretimeout function should ONLT be enabled after the notifier
register, irq group enable and add action all success, so I use below code
in V4, please help review, thanks,

+
+       ret = devm_add_action_or_reset(dev, imx_sc_wdt_action,
+                                      &imx_sc_wdd->wdt_notifier);
+       if (!ret)
+               imx_sc_wdt_info.options |= WDIOF_PRETIMEOUT;
+       else
+               dev_warn(dev, "Add action failed, pretimeout NOT supported\n");
+
        return 0;

Anson.

> 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
> >