[RFC, PATCH] watchdog on gpio

Marc Pignat
2008-01-10T15:12:48Z

watchdog driver for embedded systems with a supervisor watchdog (MAX823 or so)
connected to a gpio. This is the platform_driver and needs platform_data for
defining the gpio pin and the watchdog timeout.

Signed-off-by: Marc Pignat <marc.pignat@hevs.ch>
---

Hi!

If you've got a max823, 824 or any cpu supervisor like this connected to your
cpu by a gpio pin, you can use this watchdog driver.

Simply add this to your board specific setup file:

#include <linux/gpio_wdt.h>

static struct gpio_wdt_pdata my_wdt = {
/* WDI input connected to this gpio */
.pin = AT91_PIN_PD27,
/* The *min* timeout */
.timeout_ms = 1140
};

static struct platform_device my_watchdog_device =
{
.name = GPIO_WDT_DRIVER_NAME,
.id = 0,
.dev = {
.platform_data=&my_wdt,
}
};

then

platform_device_register(&my_watchdog_device);

This patch is against 2.6.24-rc7-git2

Comments are welcome

Regards

Marc

diff -urN a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
--- a/drivers/watchdog/gpio_wdt.c 1970-01-01 01:00:00.000000000 +0100
+++ b/drivers/watchdog/gpio_wdt.c 2008-01-10 16:06:09.000000000 +0100
@@ -0,0 +1,300 @@
+/*
+ * Generic GPIO based watchdog driver
+ *
+ * Copyright (C) 2007 Marc Pignat for www.hevs.ch
+ *
+ * This is a driver for the MAXIM MAX823 (and similar watchdog chips) connected
+ * on a generic gpio line.
+ *
+ * Principle of operation:
+ *
+ * When the WDI input is not driven (or in high impedance state), the
+ * watchdog is disabled. This mode of operations supposes that the gpio line
+ * can be put in high-impedance state (input) and is not driving too much
+ * current from the WDI pin.
+ *
+ * When the WDI input is driven, it must be toggled before the timeout,
+ * otherwise a reset is generated.
+ *
+ * Other supported chips:
+ * MAXIM: MAX824, ...
+ *
+ * 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.
+ */
+
+#include <linux/pm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/gpio_wdt.h>
+#include <linux/fs.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+
+#include <asm/uaccess.h>
+#include <asm/arch/gpio.h>
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct gpio_wdt {
+ struct gpio_wdt_pdata *pdata;
+ unsigned long driver_open;
+ char expect_close;
+};
+
+static struct gpio_wdt *watchdog;
+
+#define PFX GPIO_WDT_DRIVER_NAME":"
+
+static int gpio_wdt_keepalive(struct gpio_wdt *wdt)
+{
+ gpio_set_value(wdt->pdata->pin, 0);
+ gpio_set_value(wdt->pdata->pin, 1);
+ return 0;
+}
+
+static int gpio_wdt_stop(struct gpio_wdt *wdt)
+{
+ gpio_wdt_keepalive(wdt);
+ gpio_direction_input(wdt->pdata->pin);
+ return 0;
+}
+
+static int gpio_wdt_start(struct gpio_wdt *wdt)
+{
+ gpio_direction_output(wdt->pdata->pin, 0);
+ gpio_wdt_keepalive(wdt);
+ return 0;
+}
+
+static int gpio_wdt_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(0, &watchdog->driver_open))
+ return -EBUSY;
+
+ gpio_wdt_start(watchdog);
+ gpio_wdt_keepalive(watchdog);
+
+ return nonseekable_open(inode, file);
+}
+
+static int gpio_wdt_release(struct inode *inode, struct file *file)
+{
+ if (watchdog->expect_close == 42) {
+ gpio_wdt_stop(watchdog);
+ module_put(THIS_MODULE);
+ } else {
+ printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
+ gpio_wdt_keepalive(watchdog);
+ }
+ clear_bit(0, &watchdog->driver_open);
+ watchdog->expect_close = 0;
+ return 0;
+}
+
+static ssize_t gpio_wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
+{
+ /*
+ * Refresh the timer.
+ */
+ if (len) {
+ if (!nowayout) {
+ size_t i;
+
+ /* In case it was set long ago */
+ watchdog->expect_close = 0;
+
+ for (i = 0; i != len; i++) {
+ char c;
+
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V')
+ watchdog->expect_close = 42;
+ }
+ }
+ gpio_wdt_keepalive(watchdog);
+ }
+ return len;
+
+ gpio_wdt_keepalive(watchdog);
+ return len;
+}
+
+static struct watchdog_info ident = {
+ .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+ .firmware_version = 0,
+ .identity = GPIO_WDT_DRIVER_NAME,
+};
+
+static int gpio_wdt_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct gpio_wdt *wdt = (struct gpio_wdt *)file->private_data;
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ u32 timeout = wdt->pdata->timeout_ms;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, p);
+ case WDIOC_KEEPALIVE:
+ gpio_wdt_keepalive(wdt);
+ return 0;
+ case WDIOC_GETTIMEOUT:
+ return put_user(timeout, p);
+ case WDIOC_SETTIMEOUT:
+ return -EINVAL;
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+
+static int gpio_wdt_notify_sys(struct notifier_block *this,
+ unsigned long code, void *unused)
+{
+ if (code == SYS_DOWN || code == SYS_HALT)
+ gpio_wdt_stop(watchdog);
+
+ return NOTIFY_DONE;
+}
+
+static struct file_operations gpio_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = gpio_wdt_write,
+ .ioctl = gpio_wdt_ioctl,
+ .open = gpio_wdt_open,
+ .release = gpio_wdt_release,
+};
+
+static struct miscdevice gpio_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &gpio_wdt_fops,
+};
+
+static struct notifier_block gpio_wdt_notifier = {
+ .notifier_call = gpio_wdt_notify_sys,
+};
+
+static char banner[] __initdata = KERN_INFO PFX "fixed %d.%03d seconds timeout (nowayout= %d)\n";
+
+static int __init gpio_wdt_probe(struct platform_device *pdev)
+{
+ struct gpio_wdt_pdata *pdata = (struct gpio_wdt_pdata *)pdev->dev.platform_data;
+ int ret;
+
+ if (watchdog) {
+ printk(KERN_ERR PFX "only one device supported\n");
+ return -ENODEV;
+ }
+
+ if (!pdata) {
+ printk(KERN_ERR PFX "no private data\n");
+ return -ENODEV;
+ }
+
+ watchdog = kzalloc(sizeof(*watchdog), GFP_KERNEL);
+
+ if (!watchdog)
+ return -ENOMEM;
+
+ watchdog->pdata = pdata;
+
+ if (watchdog->pdata->pin == 0 || watchdog->pdata->timeout_ms == 0) {
+ kfree(watchdog);
+ printk(KERN_ERR PFX "invalid private data\n");
+ return -ENODEV;
+ }
+
+ ret = register_reboot_notifier(&gpio_wdt_notifier);
+ if (ret) {
+ kfree(watchdog);
+ printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret);
+ return ret;
+ }
+
+ ret = misc_register(&gpio_wdt_miscdev);
+ if (ret) {
+ unregister_reboot_notifier(&gpio_wdt_notifier);
+ kfree(watchdog);
+ printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
+ WATCHDOG_MINOR, ret);
+ return ret;
+ }
+
+ printk(banner, watchdog->pdata->timeout_ms/1000, watchdog->pdata->timeout_ms%1000, nowayout);
+
+ return 0;
+}
+
+static int __exit gpio_wdt_remove(struct platform_device *pdev)
+{
+ misc_deregister(&gpio_wdt_miscdev);
+ unregister_reboot_notifier(&gpio_wdt_notifier);
+ kfree(watchdog);
+ watchdog = NULL;
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+int gpio_wdt_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ gpio_wdt_stop(watchdog);
+ return 0;
+}
+
+int gpio_wdt_resume(struct platform_device *pdev)
+{
+ if (test_bit(0, &watchdog->driver_open))
+ gpio_wdt_start(watchdog);
+ return 0;
+}
+
+#else
+#define gpio_wdt_suspend()
+#define gpio_wdt_resume()
+#endif
+
+/* the device driver */
+static struct platform_driver gpio_wdt_driver = {
+ .probe = gpio_wdt_probe,
+ .remove = __exit_p(gpio_wdt_remove),
+ .suspend = gpio_wdt_suspend,
+ .resume = gpio_wdt_resume,
+ .driver = {
+ .name = GPIO_WDT_DRIVER_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+/* module init or kerel entry point */
+static int __init gpio_wdt_driver_init(void)
+{
+ return platform_driver_register(&gpio_wdt_driver);
+}
+
+/* module exit */
+static void __exit gpio_wdt_driver_exit(void)
+{
+ platform_driver_unregister(&gpio_wdt_driver);
+}
+
+module_init(gpio_wdt_driver_init);
+module_exit(gpio_wdt_driver_exit);
+
+MODULE_AUTHOR("Marc Pignat");
+MODULE_DESCRIPTION("Watchdog driver on a generic gpio line");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
diff -urN a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
--- a/drivers/watchdog/Kconfig 2008-01-08 17:30:30.000000000 +0100
+++ b/drivers/watchdog/Kconfig 2008-01-10 14:00:30.000000000 +0100
@@ -55,6 +55,13 @@
To compile this driver as a module, choose M here: the
module will be called softdog.

+config GPIO_WATCHDOG
+ tristate "Support for GPIO connected watchdog"
+ depends on GENERIC_GPIO
+ help
+ This option enables support for a MAX823-like watchdog connected to
+ GPIO input/output.
+
# ALPHA Architecture

# ARM Architecture
diff -urN a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
--- a/drivers/watchdog/Makefile 2008-01-08 17:30:30.000000000 +0100
+++ b/drivers/watchdog/Makefile 2008-01-10 14:01:32.000000000 +0100
@@ -121,3 +121,4 @@

# Architecture Independant
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_GPIO_WATCHDOG) += gpio_wdt.o
--- a/include/linux/gpio_wdt.h 1970-01-01 01:00:00.000000000 +0100
+++ b/include/linux/gpio_wdt.h 2008-01-10 15:48:42.000000000 +0100
@@ -0,0 +1,30 @@
+/*
+ * linux/include/gpio_watchdog.h
+ *
+ * Copyright (C) 2007 Marc Pignat for www.hevs.ch
+ *
+ * Watchdog using a MAX823 (or similar) watchdog input connected to a
+ * generic gpio line.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _LINUX_LINUX_GPIO_WDT_H
+#define _LINUX_LINUX_GPIO_WDT_H
+
+#include <asm/arch/hardware.h>
+
+#define GPIO_WDT_DRIVER_NAME "gpio_wdt"
+
+struct gpio_wdt_pdata {
+ /* the pin as defined in asm/arch/gpio.h */
+ u32 pin;
+ /* the timeout in milliseconds */
+ u32 timeout_ms;
+};
+
+#endif