This generic GPIO watchdog is used on Huawei E970 (bcm47xx)

Signed-off-by: Mathias Adam <m.adam--openwrt@adamis.de>

--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1657,6 +1657,15 @@ config WDT_MTX1
 	  Hardware driver for the MTX-1 boards. This is a watchdog timer that
 	  will reboot the machine after a 100 seconds timer expired.
 
+config GPIO_WDT
+	tristate "GPIO Hardware Watchdog"
+ 	help
+	  Hardware driver for GPIO-controlled watchdogs. GPIO pin and
+	  toggle interval settings are platform-specific. The driver
+	  will stop toggling the GPIO (i.e. machine reboots) after a
+	  100 second timer expired and no process has written to
+	  /dev/watchdog during that time.
+
 config PNX833X_WDT
 	tristate "PNX833x Hardware Watchdog"
 	depends on SOC_PNX8335
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -158,6 +158,7 @@ obj-$(CONFIG_RC32434_WDT) += rc32434_wdt
 obj-$(CONFIG_INDYDOG) += indydog.o
 obj-$(CONFIG_JZ4740_WDT) += jz4740_wdt.o
 obj-$(CONFIG_WDT_MTX1) += mtx-1_wdt.o
+obj-$(CONFIG_GPIO_WDT) += old_gpio_wdt.o
 obj-$(CONFIG_PNX833X_WDT) += pnx833x_wdt.o
 obj-$(CONFIG_SIBYTE_WDOG) += sb_wdog.o
 obj-$(CONFIG_AR7_WDT) += ar7_wdt.o
--- /dev/null
+++ b/drivers/watchdog/old_gpio_wdt.c
@@ -0,0 +1,301 @@
+/*
+ *      Driver for GPIO-controlled Hardware Watchdogs.
+ *
+ *      Copyright (C) 2013 Mathias Adam <m.adam--linux@adamis.de>
+ *
+ *      Replaces mtx1_wdt (driver for the MTX-1 Watchdog):
+ *
+ *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
+ *                              All Rights Reserved.
+ *                              http://www.4g-systems.biz
+ *
+ *      (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
+ *
+ *      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.
+ *
+ *      Neither Michael Stickel nor 4G Systems admit liability nor provide
+ *      warranty for any of this software. This material is provided
+ *      "AS-IS" and at no charge.
+ *
+ *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
+ *
+ *      Release 0.01.
+ *      Author: Michael Stickel  michael.stickel@4g-systems.biz
+ *
+ *      Release 0.02.
+ *      Author: Florian Fainelli florian@openwrt.org
+ *              use the Linux watchdog/timer APIs
+ *
+ *      Release 0.03.
+ *      Author: Mathias Adam <m.adam--linux@adamis.de>
+ *              make it a generic gpio watchdog driver
+ *
+ *      The Watchdog is configured to reset the MTX-1
+ *      if it is not triggered for 100 seconds.
+ *      It should not be triggered more often than 1.6 seconds.
+ *
+ *      A timer triggers the watchdog every 5 seconds, until
+ *      it is opened for the first time. After the first open
+ *      it MUST be triggered every 2..95 seconds.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/timer.h>
+#include <linux/completion.h>
+#include <linux/jiffies.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>
+#include <linux/old_gpio_wdt.h>
+
+static int ticks = 100 * HZ;
+
+static struct {
+	struct completion stop;
+	spinlock_t lock;
+	int running;
+	struct timer_list timer;
+	int queue;
+	int default_ticks;
+	unsigned long inuse;
+	unsigned gpio;
+	unsigned int gstate;
+	int interval;
+	int first_interval;
+} gpio_wdt_device;
+
+static void gpio_wdt_trigger(struct timer_list *unused)
+{
+	spin_lock(&gpio_wdt_device.lock);
+	if (gpio_wdt_device.running && ticks > 0)
+		ticks -= gpio_wdt_device.interval;
+
+	/* toggle wdt gpio */
+	gpio_wdt_device.gstate = !gpio_wdt_device.gstate;
+	gpio_set_value(gpio_wdt_device.gpio, gpio_wdt_device.gstate);
+
+	if (gpio_wdt_device.queue && ticks > 0)
+		mod_timer(&gpio_wdt_device.timer, jiffies + gpio_wdt_device.interval);
+	else
+		complete(&gpio_wdt_device.stop);
+	spin_unlock(&gpio_wdt_device.lock);
+}
+
+static void gpio_wdt_reset(void)
+{
+	ticks = gpio_wdt_device.default_ticks;
+}
+
+
+static void gpio_wdt_start(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_wdt_device.lock, flags);
+	if (!gpio_wdt_device.queue) {
+		gpio_wdt_device.queue = 1;
+		gpio_wdt_device.gstate = 1;
+		gpio_set_value(gpio_wdt_device.gpio, 1);
+		mod_timer(&gpio_wdt_device.timer, jiffies + gpio_wdt_device.first_interval);
+	}
+	gpio_wdt_device.running++;
+	spin_unlock_irqrestore(&gpio_wdt_device.lock, flags);
+}
+
+static int gpio_wdt_stop(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_wdt_device.lock, flags);
+	if (gpio_wdt_device.queue) {
+		gpio_wdt_device.queue = 0;
+		gpio_wdt_device.gstate = 0;
+		gpio_set_value(gpio_wdt_device.gpio, 0);
+	}
+	ticks = gpio_wdt_device.default_ticks;
+	spin_unlock_irqrestore(&gpio_wdt_device.lock, flags);
+	return 0;
+}
+
+/* Filesystem functions */
+
+static int gpio_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(0, &gpio_wdt_device.inuse))
+		return -EBUSY;
+	return nonseekable_open(inode, file);
+}
+
+
+static int gpio_wdt_release(struct inode *inode, struct file *file)
+{
+	clear_bit(0, &gpio_wdt_device.inuse);
+	return 0;
+}
+
+static long gpio_wdt_ioctl(struct file *file, unsigned int cmd,
+							unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = (int __user *)argp;
+	unsigned int value;
+	static const struct watchdog_info ident = {
+		.options = WDIOF_CARDRESET,
+		.identity = "GPIO WDT",
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		if (copy_to_user(argp, &ident, sizeof(ident)))
+			return -EFAULT;
+		break;
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		put_user(0, p);
+		break;
+	case WDIOC_SETOPTIONS:
+		if (get_user(value, p))
+			return -EFAULT;
+		if (value & WDIOS_ENABLECARD)
+			gpio_wdt_start();
+		else if (value & WDIOS_DISABLECARD)
+			gpio_wdt_stop();
+		else
+			return -EINVAL;
+		return 0;
+	case WDIOC_KEEPALIVE:
+		gpio_wdt_reset();
+		break;
+	default:
+		return -ENOTTY;
+	}
+	return 0;
+}
+
+
+static ssize_t gpio_wdt_write(struct file *file, const char *buf,
+						size_t count, loff_t *ppos)
+{
+	if (!count)
+		return -EIO;
+	gpio_wdt_reset();
+	return count;
+}
+
+static const struct file_operations gpio_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.unlocked_ioctl	= gpio_wdt_ioctl,
+	.open		= gpio_wdt_open,
+	.write		= gpio_wdt_write,
+	.release	= gpio_wdt_release,
+};
+
+
+static struct miscdevice gpio_wdt_misc = {
+	.minor	= WATCHDOG_MINOR,
+	.name	= "watchdog",
+	.fops	= &gpio_wdt_fops,
+};
+
+
+static int gpio_wdt_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct gpio_wdt_platform_data *gpio_wdt_data = pdev->dev.platform_data;
+
+	gpio_wdt_device.gpio = gpio_wdt_data->gpio;
+	gpio_wdt_device.interval = gpio_wdt_data->interval;
+	gpio_wdt_device.first_interval = gpio_wdt_data->first_interval;
+	if (gpio_wdt_device.first_interval <= 0) {
+		gpio_wdt_device.first_interval = gpio_wdt_device.interval;
+	}
+
+	ret = gpio_request(gpio_wdt_device.gpio, "gpio-wdt");
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to request gpio");
+		return ret;
+	}
+
+	spin_lock_init(&gpio_wdt_device.lock);
+	init_completion(&gpio_wdt_device.stop);
+	gpio_wdt_device.queue = 0;
+	clear_bit(0, &gpio_wdt_device.inuse);
+	timer_setup(&gpio_wdt_device.timer, gpio_wdt_trigger, 0L);
+	gpio_wdt_device.default_ticks = ticks;
+
+	gpio_wdt_start();
+	dev_info(&pdev->dev, "GPIO Hardware Watchdog driver (gpio=%i interval=%i/%i)\n",
+		gpio_wdt_data->gpio, gpio_wdt_data->first_interval, gpio_wdt_data->interval);
+	return 0;
+}
+
+static int gpio_wdt_remove(struct platform_device *pdev)
+{
+	/* FIXME: do we need to lock this test ? */
+	if (gpio_wdt_device.queue) {
+		gpio_wdt_device.queue = 0;
+		wait_for_completion(&gpio_wdt_device.stop);
+	}
+
+	gpio_free(gpio_wdt_device.gpio);
+	misc_deregister(&gpio_wdt_misc);
+	return 0;
+}
+
+static struct platform_driver gpio_wdt_driver = {
+	.probe = gpio_wdt_probe,
+	.remove = gpio_wdt_remove,
+	.driver.name = "gpio-wdt",
+	.driver.owner = THIS_MODULE,
+};
+
+static int __init gpio_wdt_init(void)
+{
+	return platform_driver_register(&gpio_wdt_driver);
+}
+arch_initcall(gpio_wdt_init);
+
+/*
+ * We do wdt initialization in two steps: arch_initcall probes the wdt
+ * very early to start pinging the watchdog (misc devices are not yet
+ * available), and later module_init() just registers the misc device.
+ */
+static int gpio_wdt_init_late(void)
+{
+	int ret;
+
+	ret = misc_register(&gpio_wdt_misc);
+	if (ret < 0) {
+		pr_err("GPIO_WDT: failed to register misc device\n");
+		return ret;
+	}
+	return 0;
+}
+#ifndef MODULE
+module_init(gpio_wdt_init_late);
+#endif
+
+static void __exit gpio_wdt_exit(void)
+{
+	platform_driver_unregister(&gpio_wdt_driver);
+}
+module_exit(gpio_wdt_exit);
+
+MODULE_AUTHOR("Michael Stickel, Florian Fainelli, Mathias Adam");
+MODULE_DESCRIPTION("Driver for GPIO hardware watchdogs");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_ALIAS("platform:gpio-wdt");
--- /dev/null
+++ b/include/linux/old_gpio_wdt.h
@@ -0,0 +1,21 @@
+/*
+ *  Definitions for the GPIO watchdog driver
+ *
+ *  Copyright (C) 2013 Mathias Adam <m.adam--linux@adamis.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ */
+
+#ifndef _GPIO_WDT_H_
+#define _GPIO_WDT_H_
+
+struct gpio_wdt_platform_data {
+	int	gpio;		/* GPIO line number */
+	int	interval;	/* watchdog reset interval in system ticks */
+	int	first_interval;	/* first wd reset interval in system ticks */
+};
+
+#endif /* _GPIO_WDT_H_ */
