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Date: Mon, 30 Jan 2017 10:55:29 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: H Hartley Sweeten <hsweeten@...ionengravers.com>
Cc: linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
Wim Van Sebroeck <wim@...ana.be>
Subject: Re: [PATCH 1/2] watchdog: ep93xx_wdt: cleanup and let the core
handle the heartbeat
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@...ionengravers.com>
> Cc: Wim Van Sebroeck <wim@...ana.be>
> Cc: Guenter Roeck <linux@...ck-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@...ertech.it>");
> MODULE_AUTHOR("H Hartley Sweeten <hsweeten@...ionengravers.com>");
> MODULE_DESCRIPTION("EP93xx Watchdog");
> MODULE_LICENSE("GPL");
> -MODULE_VERSION(WDT_VERSION);
> --
> 2.10.0
>
> --
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