From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.active-venture.com ([67.228.131.205]:62455 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753848Ab3KZRyg (ORCPT ); Tue, 26 Nov 2013 12:54:36 -0500 Message-ID: <5294E05A.3040104@roeck-us.net> Date: Tue, 26 Nov 2013 09:54:34 -0800 From: Guenter Roeck MIME-Version: 1.0 To: Alexander Shiyan , linux-watchdog@vger.kernel.org CC: devicetree@vger.kernel.org, Wim Van Sebroeck , Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Grant Likely Subject: Re: [PATCH v2] watchdog: GPIO-controlled watchdog References: <1385483188-12221-1-git-send-email-shc_work@mail.ru> In-Reply-To: <1385483188-12221-1-git-send-email-shc_work@mail.ru> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 11/26/2013 08:26 AM, Alexander Shiyan wrote: > This patch adds a watchdog driver for devices controlled through GPIO, > (Analog Devices ADM706, IC 555 etc). > > Signed-off-by: Alexander Shiyan > --- A list of changes since v1 would be helpful. > .../devicetree/bindings/watchdog/gpio-wdt.txt | 23 ++ > drivers/watchdog/Kconfig | 8 + > drivers/watchdog/Makefile | 1 + > drivers/watchdog/gpio_wdt.c | 246 +++++++++++++++++++++ > 4 files changed, 278 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..08ba8e5 > --- /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". Should ? > +- gpios: From common gpio binding; gpio connection to WDT reset pin. > +- wdt-gpio,hw_algo: The algorithm used by the driver. Should be one > + of the following values: Should ? > + - 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. > +- wdt-gpio,hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds). > + > +Example: > + watchdog: watchdog { > + /* ADM706 */ > + compatible = "linux,wdt-gpio"; Oddly enough, the bindings could be used by non-Linux operating systems, but who am I to argue. Fine if this is what the DT maintainers want to see. > + gpios = <&gpio3 9 GPIO_ACTIVE_LOW>; > + wdt-gpio,hw_algo = "toggle"; > + wdt-gpio,hw_margin_ms = <1600>; Is this a new means to name device specific properties ? "wdt-gpio" in those bindings is quite redundant with "wdt-gpio" in the compatible property. Again, though, who am I to argue. > + }; > 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..c7166be > --- /dev/null > +++ b/drivers/watchdog/gpio_wdt.c > @@ -0,0 +1,246 @@ > +/* > + * Driver for watchdog device controlled through GPIO-line > + * > + * Author: 2013, Alexander Shiyan > + * > + * 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 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#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 int 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) > + return gpio_direction_input(priv->gpio); > + No disable for 'level' watchdogs ? Shouldn't it be set to the opposite of priv->state ? > + return 0; Since this is an internal function which never returns anything but 0, you might as well make it void. > +} > + > +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); > + > + return gpio_wdt_disable(priv); > +} > + > +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 0; > +} > + > +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_before(jiffies, priv->last_jiffies + > + msecs_to_jiffies(wdd->timeout * 1000))) { > + /* 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); Pretty arbitrary toggle time. Should this be a property ? > + gpio_set_value_cansleep(priv->gpio, priv->active_low); > + break; > + } > + } else > + dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n"); Coding style (chapter 3): else should be in { } too. > +} > + > +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; > + case SYS_DOWN: This case statement is unnecessary. > + 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; > + const __be32 *prp; > + u32 hw_margin; > + 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); > + !! is unnecessary for assignments to booleans. > + ret = devm_gpio_request_one(&pdev->dev, priv->gpio, GPIOF_IN, > + dev_name(&pdev->dev)); > + if (ret) > + return ret; > + > + prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_algo", NULL); > + if (!prp) > + return -EINVAL; I am a bit concerned about using of_get_property() to read a string. If the provided property is an integer, one can only hope that nothing odd happens. How about using of_property_read_string() instead ? That would at least provide some protection. > + if (!strncmp((const char *)prp, "toggle", 6)) > + priv->hw_algo = HW_ALGO_TOGGLE; > + else if (!strncmp((const char *)prp, "level", 5)) > + priv->hw_algo = HW_ALGO_LEVEL; > + else > + return -ENOTSUPP; This suggests that the value is valid but not supported. -EINVAL may be better. > + > + prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_margin_ms", NULL); > + if (!prp) > + return -EINVAL; There is also of_property_read_u32(). > + hw_margin = be32_to_cpu(*prp); > + /* Disallow values lower than 2 and higher than 65535 ms */ > + if ((hw_margin < 2) || (hw_margin > 65535)) > + return -EINVAL; > + > + /* Use safe value (2/3 of real timeout) */ > + priv->hw_margin = msecs_to_jiffies(hw_margin * 2 / 3); > + Hope this is safe enough. I would have used 1/2, but that is really up to you to decide. > + 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); > + > + priv->notifier.notifier_call = gpio_wdt_notify_sys; > + ret = register_reboot_notifier(&priv->notifier); > + if (ret) > + return ret; > + > + return watchdog_register_device(&priv->wdd); If this fails you don't call unregister_reboot_notifier. > +} > + > +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 "); > +MODULE_DESCRIPTION("GPIO Watchdog"); > +MODULE_LICENSE("GPL"); > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH v2] watchdog: GPIO-controlled watchdog Date: Tue, 26 Nov 2013 09:54:34 -0800 Message-ID: <5294E05A.3040104@roeck-us.net> References: <1385483188-12221-1-git-send-email-shc_work@mail.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1385483188-12221-1-git-send-email-shc_work-JGs/UdohzUI@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alexander Shiyan , linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wim Van Sebroeck , Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Grant Likely List-Id: devicetree@vger.kernel.org On 11/26/2013 08:26 AM, Alexander Shiyan wrote: > This patch adds a watchdog driver for devices controlled through GPIO, > (Analog Devices ADM706, IC 555 etc). > > Signed-off-by: Alexander Shiyan > --- A list of changes since v1 would be helpful. > .../devicetree/bindings/watchdog/gpio-wdt.txt | 23 ++ > drivers/watchdog/Kconfig | 8 + > drivers/watchdog/Makefile | 1 + > drivers/watchdog/gpio_wdt.c | 246 +++++++++++++++++++++ > 4 files changed, 278 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..08ba8e5 > --- /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". Should ? > +- gpios: From common gpio binding; gpio connection to WDT reset pin. > +- wdt-gpio,hw_algo: The algorithm used by the driver. Should be one > + of the following values: Should ? > + - 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. > +- wdt-gpio,hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds). > + > +Example: > + watchdog: watchdog { > + /* ADM706 */ > + compatible = "linux,wdt-gpio"; Oddly enough, the bindings could be used by non-Linux operating systems, but who am I to argue. Fine if this is what the DT maintainers want to see. > + gpios = <&gpio3 9 GPIO_ACTIVE_LOW>; > + wdt-gpio,hw_algo = "toggle"; > + wdt-gpio,hw_margin_ms = <1600>; Is this a new means to name device specific properties ? "wdt-gpio" in those bindings is quite redundant with "wdt-gpio" in the compatible property. Again, though, who am I to argue. > + }; > 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..c7166be > --- /dev/null > +++ b/drivers/watchdog/gpio_wdt.c > @@ -0,0 +1,246 @@ > +/* > + * Driver for watchdog device controlled through GPIO-line > + * > + * Author: 2013, Alexander Shiyan > + * > + * 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 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#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 int 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) > + return gpio_direction_input(priv->gpio); > + No disable for 'level' watchdogs ? Shouldn't it be set to the opposite of priv->state ? > + return 0; Since this is an internal function which never returns anything but 0, you might as well make it void. > +} > + > +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); > + > + return gpio_wdt_disable(priv); > +} > + > +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 0; > +} > + > +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_before(jiffies, priv->last_jiffies + > + msecs_to_jiffies(wdd->timeout * 1000))) { > + /* 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); Pretty arbitrary toggle time. Should this be a property ? > + gpio_set_value_cansleep(priv->gpio, priv->active_low); > + break; > + } > + } else > + dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n"); Coding style (chapter 3): else should be in { } too. > +} > + > +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; > + case SYS_DOWN: This case statement is unnecessary. > + 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; > + const __be32 *prp; > + u32 hw_margin; > + 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); > + !! is unnecessary for assignments to booleans. > + ret = devm_gpio_request_one(&pdev->dev, priv->gpio, GPIOF_IN, > + dev_name(&pdev->dev)); > + if (ret) > + return ret; > + > + prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_algo", NULL); > + if (!prp) > + return -EINVAL; I am a bit concerned about using of_get_property() to read a string. If the provided property is an integer, one can only hope that nothing odd happens. How about using of_property_read_string() instead ? That would at least provide some protection. > + if (!strncmp((const char *)prp, "toggle", 6)) > + priv->hw_algo = HW_ALGO_TOGGLE; > + else if (!strncmp((const char *)prp, "level", 5)) > + priv->hw_algo = HW_ALGO_LEVEL; > + else > + return -ENOTSUPP; This suggests that the value is valid but not supported. -EINVAL may be better. > + > + prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_margin_ms", NULL); > + if (!prp) > + return -EINVAL; There is also of_property_read_u32(). > + hw_margin = be32_to_cpu(*prp); > + /* Disallow values lower than 2 and higher than 65535 ms */ > + if ((hw_margin < 2) || (hw_margin > 65535)) > + return -EINVAL; > + > + /* Use safe value (2/3 of real timeout) */ > + priv->hw_margin = msecs_to_jiffies(hw_margin * 2 / 3); > + Hope this is safe enough. I would have used 1/2, but that is really up to you to decide. > + 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); > + > + priv->notifier.notifier_call = gpio_wdt_notify_sys; > + ret = register_reboot_notifier(&priv->notifier); > + if (ret) > + return ret; > + > + return watchdog_register_device(&priv->wdd); If this fails you don't call unregister_reboot_notifier. > +} > + > +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 "); > +MODULE_DESCRIPTION("GPIO Watchdog"); > +MODULE_LICENSE("GPL"); > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html