diff options
Diffstat (limited to 'drivers/watchdog/gpio_wdt.c')
| -rw-r--r-- | drivers/watchdog/gpio_wdt.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c new file mode 100644 index 000000000..ea77cae03 --- /dev/null +++ b/drivers/watchdog/gpio_wdt.c @@ -0,0 +1,205 @@ +/* + * 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/gpio/consumer.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/watchdog.h> + +#define SOFT_TIMEOUT_MIN 1 +#define SOFT_TIMEOUT_DEF 60 + +enum { + HW_ALGO_TOGGLE, + HW_ALGO_LEVEL, +}; + +struct gpio_wdt_priv { + struct gpio_desc *gpiod; + bool state; + bool always_running; + unsigned int hw_algo; + struct watchdog_device wdd; +}; + +static void gpio_wdt_disable(struct gpio_wdt_priv *priv) +{ + /* Eternal ping */ + gpiod_set_value_cansleep(priv->gpiod, 1); + + /* Put GPIO back to tristate */ + if (priv->hw_algo == HW_ALGO_TOGGLE) + gpiod_direction_input(priv->gpiod); +} + +static int gpio_wdt_ping(struct watchdog_device *wdd) +{ + struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); + + switch (priv->hw_algo) { + case HW_ALGO_TOGGLE: + /* Toggle output pin */ + priv->state = !priv->state; + gpiod_set_value_cansleep(priv->gpiod, priv->state); + break; + case HW_ALGO_LEVEL: + /* Pulse */ + gpiod_set_value_cansleep(priv->gpiod, 1); + udelay(1); + gpiod_set_value_cansleep(priv->gpiod, 0); + break; + } + return 0; +} + +static int gpio_wdt_start(struct watchdog_device *wdd) +{ + struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); + + priv->state = 0; + gpiod_direction_output(priv->gpiod, priv->state); + + set_bit(WDOG_HW_RUNNING, &wdd->status); + + return gpio_wdt_ping(wdd); +} + +static int gpio_wdt_stop(struct watchdog_device *wdd) +{ + struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); + + if (!priv->always_running) { + gpio_wdt_disable(priv); + } else { + set_bit(WDOG_HW_RUNNING, &wdd->status); + } + + return 0; +} + +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, +}; + +static int gpio_wdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + struct gpio_wdt_priv *priv; + enum gpiod_flags gflags; + unsigned int hw_margin; + const char *algo; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, priv); + + ret = of_property_read_string(np, "hw_algo", &algo); + if (ret) + return ret; + if (!strcmp(algo, "toggle")) { + priv->hw_algo = HW_ALGO_TOGGLE; + gflags = GPIOD_IN; + } else if (!strcmp(algo, "level")) { + priv->hw_algo = HW_ALGO_LEVEL; + gflags = GPIOD_OUT_LOW; + } else { + return -EINVAL; + } + + priv->gpiod = devm_gpiod_get(dev, NULL, gflags); + if (IS_ERR(priv->gpiod)) + return PTR_ERR(priv->gpiod); + + ret = of_property_read_u32(np, + "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; + + priv->always_running = of_property_read_bool(np, + "always-running"); + + 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_hw_heartbeat_ms = hw_margin; + priv->wdd.parent = dev; + priv->wdd.timeout = SOFT_TIMEOUT_DEF; + + watchdog_init_timeout(&priv->wdd, 0, &pdev->dev); + + watchdog_stop_on_reboot(&priv->wdd); + + if (priv->always_running) + gpio_wdt_start(&priv->wdd); + + ret = watchdog_register_device(&priv->wdd); + + return ret; +} + +static int gpio_wdt_remove(struct platform_device *pdev) +{ + struct gpio_wdt_priv *priv = platform_get_drvdata(pdev); + + 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", + .of_match_table = gpio_wdt_dt_ids, + }, + .probe = gpio_wdt_probe, + .remove = gpio_wdt_remove, +}; + +#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL +static int __init gpio_wdt_init(void) +{ + return platform_driver_register(&gpio_wdt_driver); +} +arch_initcall(gpio_wdt_init); +#else +module_platform_driver(gpio_wdt_driver); +#endif + +MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>"); +MODULE_DESCRIPTION("GPIO Watchdog"); +MODULE_LICENSE("GPL"); |