diff options
Diffstat (limited to 'drivers/watchdog/gpio_wdt.c')
| -rw-r--r-- | drivers/watchdog/gpio_wdt.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c new file mode 100644 index 000000000000..220a9e07cfd5 --- /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) + 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"); |