Re: [PATCH 1/2] watchdog: ep93xx_wdt: cleanup and let the core handle the heartbeat

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Jan 30, 2017 at 09:55:47AM -0700, H Hartley Sweeten wrote:
> Cleanup this driver and remove the 200ms heartbeat timer. The core now
> has the ability to handle the heartbeat.
> 
> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/watchdog/ep93xx_wdt.c | 115 +++++++++++++++++-------------------------
>  1 file changed, 46 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/watchdog/ep93xx_wdt.c b/drivers/watchdog/ep93xx_wdt.c
> index 0a4d7cc..756ca47 100644
> --- a/drivers/watchdog/ep93xx_wdt.c
> +++ b/drivers/watchdog/ep93xx_wdt.c
> @@ -19,81 +19,55 @@
>   * for us to rely on the user space daemon alone. So we ping the
>   * wdt each ~200msec and eventually stop doing it if the user space
>   * daemon dies.
> - *
> - * TODO:
> - *
> - *	- Test last reset from watchdog status
> - *	- Add a few missing ioctls
>   */
>  
>  #include <linux/platform_device.h>
>  #include <linux/module.h>
>  #include <linux/watchdog.h>
> -#include <linux/timer.h>
>  #include <linux/io.h>
>  
> -#define WDT_VERSION	"0.4"
> -
> -/* default timeout (secs) */
> -#define WDT_TIMEOUT 30
> -

Personally I like those constants, even if used only once (I know, it is a good
candidate for bikeshedding). Two reasons: 1) It is already there, and 2) It
helps seeing the default without having to dig into the code.

>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  module_param(nowayout, bool, 0);
>  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
>  
> -static unsigned int timeout = WDT_TIMEOUT;
> -module_param(timeout, uint, 0);
> -MODULE_PARM_DESC(timeout,
> -	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
> -				__MODULE_STRING(WDT_TIMEOUT) ")");
> -

Are you sure you want to take away the means to set the timeout with
a module parameter ? You could easily retain the module parameter
and call watchdog_init_timeout(wdd, timeout, dev). The parameter should
then be initialized with 0, though, to have the watchdog core take the
timeout from devicetree if provided.

> -static void __iomem *mmio_base;
> -static struct timer_list timer;
> -static unsigned long next_heartbeat;
> -
>  #define EP93XX_WATCHDOG		0x00
>  #define EP93XX_WDSTATUS		0x04
>  
> -/* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
> -#define WDT_INTERVAL (HZ/5)
> -
> -static void ep93xx_wdt_timer_ping(unsigned long data)
> -{
> -	if (time_before(jiffies, next_heartbeat))
> -		writel(0x5555, mmio_base + EP93XX_WATCHDOG);
> -
> -	/* Re-set the timer interval */
> -	mod_timer(&timer, jiffies + WDT_INTERVAL);
> -}
> +struct ep93xx_wdt_priv {
> +	void __iomem *mmio;
> +	struct watchdog_device wdd;
> +};
>  
>  static int ep93xx_wdt_start(struct watchdog_device *wdd)
>  {
> -	next_heartbeat = jiffies + (timeout * HZ);
> +	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
>  
> -	writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
> -	mod_timer(&timer, jiffies + WDT_INTERVAL);
> +	writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
>  
>  	return 0;
>  }
>  
>  static int ep93xx_wdt_stop(struct watchdog_device *wdd)
>  {
> -	del_timer_sync(&timer);
> -	writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
> +	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
>  
>  	return 0;
>  }
>  
> -static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
> +static int ep93xx_wdt_ping(struct watchdog_device *wdd)
>  {
> -	/* user land ping */
> -	next_heartbeat = jiffies + (timeout * HZ);
> +	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
>  
>  	return 0;
>  }
>  
>  static const struct watchdog_info ep93xx_wdt_ident = {
>  	.options	= WDIOF_CARDRESET |
> +			  WDIOF_SETTIMEOUT |
>  			  WDIOF_MAGICCLOSE |
>  			  WDIOF_KEEPALIVEPING,
>  	.identity	= "EP93xx Watchdog",
> @@ -103,47 +77,48 @@ static struct watchdog_ops ep93xx_wdt_ops = {
>  	.owner		= THIS_MODULE,
>  	.start		= ep93xx_wdt_start,
>  	.stop		= ep93xx_wdt_stop,
> -	.ping		= ep93xx_wdt_keepalive,
> -};
> -
> -static struct watchdog_device ep93xx_wdt_wdd = {
> -	.info		= &ep93xx_wdt_ident,
> -	.ops		= &ep93xx_wdt_ops,
> +	.ping		= ep93xx_wdt_ping,
>  };
>  
>  static int ep93xx_wdt_probe(struct platform_device *pdev)
>  {
> +	struct ep93xx_wdt_priv *priv;
> +	struct watchdog_device *wdd;
>  	struct resource *res;
>  	unsigned long val;
> -	int err;
> +	int ret;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	mmio_base = devm_ioremap_resource(&pdev->dev, res);
> -	if (IS_ERR(mmio_base))
> -		return PTR_ERR(mmio_base);
> +	priv->mmio = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(priv->mmio))
> +		return PTR_ERR(priv->mmio);
> +
> +	val = readl(priv->mmio + EP93XX_WATCHDOG);
>  
> -	if (timeout < 1 || timeout > 3600) {
> -		timeout = WDT_TIMEOUT;
> -		dev_warn(&pdev->dev,
> -			"timeout value must be 1<=x<=3600, using %d\n",
> -			timeout);
> -	}
> +	wdd = &priv->wdd;
> +	wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
> +	wdd->info = &ep93xx_wdt_ident;
> +	wdd->ops = &ep93xx_wdt_ops;
> +	wdd->timeout = 30;
> +	wdd->min_timeout = 1;
> +	wdd->max_hw_heartbeat_ms = 200;
> +	wdd->parent = &pdev->dev;
>  
> -	val = readl(mmio_base + EP93XX_WATCHDOG);
> -	ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
> -	ep93xx_wdt_wdd.timeout = timeout;
> -	ep93xx_wdt_wdd.parent = &pdev->dev;
> +	watchdog_set_nowayout(wdd, nowayout);
>  
> -	watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);
> +	watchdog_set_drvdata(wdd, priv);
>  
> -	setup_timer(&timer, ep93xx_wdt_timer_ping, 1);
> +	ret = watchdog_register_device(wdd);

Looks like a perfect candidate for devm_watchdog_register_device().

> +	if (ret)
> +		return ret;
>  
> -	err = watchdog_register_device(&ep93xx_wdt_wdd);
> -	if (err)
> -		return err;
> +	platform_set_drvdata(pdev, priv);
>  
> -	dev_info(&pdev->dev,
> -		"EP93XX watchdog, driver version " WDT_VERSION "%s\n",
> +	dev_info(&pdev->dev, "EP93XX watchdog driver %s\n",
>  		(val & 0x08) ? " (nCS1 disable detected)" : "");
>  
>  	return 0;
> @@ -151,7 +126,10 @@ static int ep93xx_wdt_probe(struct platform_device *pdev)
>  
>  static int ep93xx_wdt_remove(struct platform_device *pdev)
>  {
> -	watchdog_unregister_device(&ep93xx_wdt_wdd);
> +	struct ep93xx_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> +	watchdog_unregister_device(&priv->wdd);
> +
>  	return 0;
>  }
>  
> @@ -170,4 +148,3 @@ MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
>  MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
>  MODULE_DESCRIPTION("EP93xx Watchdog");
>  MODULE_LICENSE("GPL");
> -MODULE_VERSION(WDT_VERSION);
> -- 
> 2.10.0
> 
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