Re: [PATCH v3] watchdog: GPIO-controlled watchdog

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

On 11/29/2013 11:54 PM, Alexander Shiyan wrote:
> This patch adds a watchdog driver for devices controlled through GPIO,
> (Analog Devices ADM706, Maxim MAX823, National NE555 etc).
>
> Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> ---

Looks pretty good, except for a single nitpick below (sorry I didn't notice that one earlier).

Also, as mentioned before, a changelog describing what changed and what didn't
would be really helpful.

Thanks,
Guenter

>   .../devicetree/bindings/watchdog/gpio-wdt.txt      |  23 ++
>   drivers/watchdog/Kconfig                           |   8 +
>   drivers/watchdog/Makefile                          |   1 +
>   drivers/watchdog/gpio_wdt.c                        | 254 +++++++++++++++++++++
>   4 files changed, 286 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
>   create mode 100644 drivers/watchdog/gpio_wdt.c
>
> diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> new file mode 100644
> index 0000000..37afec1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> @@ -0,0 +1,23 @@
> +* GPIO-controlled Watchdog
> +
> +Required Properties:
> +- compatible: Should contain "linux,wdt-gpio".
> +- gpios: From common gpio binding; gpio connection to WDT reset pin.
> +- hw_algo: The algorithm used by the driver. Should be one of the
> +  following values:
> +  - toggle: Either a high-to-low or a low-to-high transition clears
> +    the WDT counter. The watchdog timer is disabled when GPIO is
> +    left floating or connected to a three-state buffer.
> +  - level: Low or high level starts counting WDT timeout,
> +    the opposite level disables the WDT. Active level is determined
> +    by the GPIO flags.
> +- hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).
> +
> +Example:
> +	watchdog: watchdog {
> +		/* ADM706 */
> +		compatible = "linux,wdt-gpio";
> +		gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
> +		hw_algo = "toggle";
> +		hw_margin_ms = <1600>;

Last call for comments from devicetree maintainers ...

> +	};
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 5be6e91..968a882 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -87,6 +87,14 @@ config DA9055_WATCHDOG
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called da9055_wdt.
>
> +config GPIO_WATCHDOG
> +	tristate "Watchdog device controlled through GPIO-line"
> +	depends on OF_GPIO
> +	select WATCHDOG_CORE
> +	help
> +	  If you say yes here you get support for watchdog device
> +	  controlled through GPIO-line.
> +
>   config WM831X_WATCHDOG
>   	tristate "WM831x watchdog"
>   	depends on MFD_WM831X
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 91bd95a..dc17275 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -171,6 +171,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>   # Architecture Independent
>   obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
>   obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
> +obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o
>   obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>   obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>   obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
> diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
> new file mode 100644
> index 0000000..1e02dd6
> --- /dev/null
> +++ b/drivers/watchdog/gpio_wdt.c
> @@ -0,0 +1,254 @@
> +/*
> + * Driver for watchdog device controlled through GPIO-line
> + *
> + * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/watchdog.h>
> +
> +#define SOFT_TIMEOUT_MIN	1
> +#define SOFT_TIMEOUT_DEF	60
> +#define SOFT_TIMEOUT_MAX	0xffff
> +
> +enum {
> +	HW_ALGO_TOGGLE,
> +	HW_ALGO_LEVEL,
> +};
> +
> +struct gpio_wdt_priv {
> +	int			gpio;
> +	bool			active_low;
> +	bool			state;
> +	unsigned int		hw_algo;
> +	unsigned int		hw_margin;
> +	unsigned long		last_jiffies;
> +	struct notifier_block	notifier;
> +	struct timer_list	timer;
> +	struct watchdog_device	wdd;
> +};
> +
> +static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
> +{
> +	gpio_set_value_cansleep(priv->gpio, !priv->active_low);
> +
> +	/* Put GPIO back to tristate */
> +	if (priv->hw_algo == HW_ALGO_TOGGLE)
> +		gpio_direction_input(priv->gpio);
> +}
> +
> +static int gpio_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	priv->state = priv->active_low;
> +	gpio_direction_output(priv->gpio, priv->state);
> +	priv->last_jiffies = jiffies;
> +	mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
> +
> +	return 0;
> +}
> +
> +static int gpio_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	mod_timer(&priv->timer, 0);
> +	gpio_wdt_disable(priv);
> +
> +	return 0;
> +}
> +
> +static int gpio_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	priv->last_jiffies = jiffies;
> +
> +	return 0;
> +}
> +
> +static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
> +{
> +	wdd->timeout = t;
> +
> +	return gpio_wdt_ping(wdd);
> +}
> +
> +static void gpio_wdt_hwping(unsigned long data)
> +{
> +	struct watchdog_device *wdd = (struct watchdog_device *)data;
> +	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	if (time_after(jiffies, priv->last_jiffies +
> +		       msecs_to_jiffies(wdd->timeout * 1000))) {
> +		dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
> +		return;
> +	}
> +
> +	/* Restart timer */
> +	mod_timer(&priv->timer, jiffies + priv->hw_margin);
> +
> +	switch (priv->hw_algo) {
> +	case HW_ALGO_TOGGLE:
> +		/* Toggle output pin */
> +		priv->state = !priv->state;
> +		gpio_set_value_cansleep(priv->gpio, priv->state);
> +		break;
> +	case HW_ALGO_LEVEL:
> +		/* Pulse */
> +		gpio_set_value_cansleep(priv->gpio, !priv->active_low);
> +		udelay(1);
> +		gpio_set_value_cansleep(priv->gpio, priv->active_low);
> +		break;
> +	}
> +}
> +
> +static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
> +			       void *unused)
> +{
> +	struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
> +						  notifier);
> +
> +	mod_timer(&priv->timer, 0);
> +
> +	switch (code) {
> +	case SYS_HALT:
> +	case SYS_POWER_OFF:
> +		gpio_wdt_disable(priv);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static const struct watchdog_info gpio_wdt_ident = {
> +	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
> +			  WDIOF_SETTIMEOUT,
> +	.identity	= "GPIO Watchdog",
> +};
> +
> +static const struct watchdog_ops gpio_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= gpio_wdt_start,
> +	.stop		= gpio_wdt_stop,
> +	.ping		= gpio_wdt_ping,
> +	.set_timeout	= gpio_wdt_set_timeout,
> +};
> +
> +static int gpio_wdt_probe(struct platform_device *pdev)
> +{
> +	struct gpio_wdt_priv *priv;
> +	enum of_gpio_flags flags;
> +	unsigned int hw_margin;
> +	unsigned long f = 0;
> +	const char *algo;
> +	int ret;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
> +	if (!gpio_is_valid(priv->gpio))
> +		return priv->gpio;
> +
> +	priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
> +
> +	ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
> +	if (ret)
> +		return ret;
> +	if (!strncmp(algo, "toggle", 6)) {
> +		priv->hw_algo = HW_ALGO_TOGGLE;
> +		f = GPIOF_IN;
> +	} else if (!strncmp(algo, "level", 5)) {
> +		priv->hw_algo = HW_ALGO_LEVEL;
> +		f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
> +				    dev_name(&pdev->dev));
> +	if (ret)
> +		return ret;
> +
> +	ret = of_property_read_u32(pdev->dev.of_node,
> +				   "hw_margin_ms", &hw_margin);
> +	if (ret)
> +		return ret;
> +	/* Disallow values lower than 2 and higher than 65535 ms */
> +	if ((hw_margin < 2) || (hw_margin > 65535))

Unnecessary ( ).

> +		return -EINVAL;
> +
> +	/* Use safe value (1/2 of real timeout) */
> +	priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
> +
> +	watchdog_set_drvdata(&priv->wdd, priv);
> +
> +	priv->wdd.info		= &gpio_wdt_ident;
> +	priv->wdd.ops		= &gpio_wdt_ops;
> +	priv->wdd.min_timeout	= SOFT_TIMEOUT_MIN;
> +	priv->wdd.max_timeout	= SOFT_TIMEOUT_MAX;
> +
> +	if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
> +		priv->wdd.timeout = SOFT_TIMEOUT_DEF;
> +
> +	setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
> +
> +	ret = watchdog_register_device(&priv->wdd);
> +	if (ret)
> +		return ret;
> +
> +	priv->notifier.notifier_call = gpio_wdt_notify_sys;
> +	ret = register_reboot_notifier(&priv->notifier);
> +	if (ret)
> +		watchdog_unregister_device(&priv->wdd);
> +
> +	return ret;
> +}
> +
> +static int gpio_wdt_remove(struct platform_device *pdev)
> +{
> +	struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> +	del_timer_sync(&priv->timer);
> +	unregister_reboot_notifier(&priv->notifier);
> +	watchdog_unregister_device(&priv->wdd);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id gpio_wdt_dt_ids[] = {
> +	{ .compatible = "linux,wdt-gpio", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
> +
> +static struct platform_driver gpio_wdt_driver = {
> +	.driver	= {
> +		.name		= "gpio-wdt",
> +		.owner		= THIS_MODULE,
> +		.of_match_table	= gpio_wdt_dt_ids,
> +	},
> +	.probe	= gpio_wdt_probe,
> +	.remove	= gpio_wdt_remove,
> +};
> +module_platform_driver(gpio_wdt_driver);
> +
> +MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
> +MODULE_DESCRIPTION("GPIO Watchdog");
> +MODULE_LICENSE("GPL");
>