--- /dev/null
+/*
+ * Acquire Single Board Computer Watchdog Timer driver
+ *
+ * Based on wdt.c. Original copyright messages:
+ *
+ * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
+ * All Rights Reserved.
+ *
+ * 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 Alan Cox nor CymruNet Ltd. admit liability nor provide
+ * warranty for any of this software. This material is provided
+ * "AS-IS" and at no charge.
+ *
+ * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *
+ * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
+ * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
+ * Can't add timeout - driver doesn't allow changing value
+ */
+
+/*
+ * Theory of Operation:
+ * The Watch-Dog Timer is provided to ensure that standalone
+ * Systems can always recover from catastrophic conditions that
+ * caused the CPU to crash. This condition may have occurred by
+ * external EMI or a software bug. When the CPU stops working
+ * correctly, hardware on the board will either perform a hardware
+ * reset (cold boot) or a non-maskable interrupt (NMI) to bring the
+ * system back to a known state.
+ *
+ * The Watch-Dog Timer is controlled by two I/O Ports.
+ * 443 hex - Read - Enable or refresh the Watch-Dog Timer
+ * 043 hex - Read - Disable the Watch-Dog Timer
+ *
+ * To enable the Watch-Dog Timer, a read from I/O port 443h must
+ * be performed. This will enable and activate the countdown timer
+ * which will eventually time out and either reset the CPU or cause
+ * an NMI depending on the setting of a jumper. To ensure that this
+ * reset condition does not occur, the Watch-Dog Timer must be
+ * periodically refreshed by reading the same I/O port 443h.
+ * The Watch-Dog Timer is disabled by reading I/O port 043h.
+ *
+ * The Watch-Dog Timer Time-Out Period is set via jumpers.
+ * It can be 1, 2, 10, 20, 110 or 220 seconds.
+ */
+
+/*
+ * Includes, defines, variables, module parameters, ...
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+/* Includes */
+#include <linux/module.h> /* For module specific items */
+#include <linux/moduleparam.h> /* For new moduleparam's */
+#include <linux/types.h> /* For standard types (like size_t) */
+#include <linux/errno.h> /* For the -ENODEV/... values */
+#include <linux/kernel.h> /* For printk/panic/... */
+#include <linux/miscdevice.h> /* For struct miscdevice */
+#include <linux/watchdog.h> /* For the watchdog specific items */
+#include <linux/fs.h> /* For file operations */
+#include <linux/ioport.h> /* For io-port access */
+#include <linux/platform_device.h> /* For platform_driver framework */
+#include <linux/init.h> /* For __init/__exit/... */
+#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+#include <linux/io.h> /* For inb/outb/... */
+
+/* Module information */
+#define DRV_NAME "acquirewdt"
+#define WATCHDOG_NAME "Acquire WDT"
+/* There is no way to see what the correct time-out period is */
+#define WATCHDOG_HEARTBEAT 0
+
+/* internal variables */
+/* the watchdog platform device */
+static struct platform_device *acq_platform_device;
+static unsigned long acq_is_open;
+static char expect_close;
+
+/* module parameters */
+/* You must set this - there is no sane way to probe for this board. */
+static int wdt_stop = 0x43;
+module_param(wdt_stop, int, 0);
+MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
+
+/* You must set this - there is no sane way to probe for this board. */
+static int wdt_start = 0x443;
+module_param(wdt_start, int, 0);
+MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+ "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+/*
+ * Watchdog Operations
+ */
+
+static void acq_keepalive(void)
+{
+ /* Write a watchdog value */
+ inb_p(wdt_start);
+}
+
+static void acq_stop(void)
+{
+ /* Turn the card off */
+ inb_p(wdt_stop);
+}
+
+/*
+ * /dev/watchdog handling
+ */
+
+static ssize_t acq_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ /* See if we got the magic character 'V' and reload the timer */
+ if (count) {
+ if (!nowayout) {
+ size_t i;
+ /* note: just in case someone wrote the magic character
+ five months ago... */
+ expect_close = 0;
+ /* scan to see whether or not we got the
+ magic character */
+ for (i = 0; i != count; i++) {
+ char c;
+ if (get_user(c, buf + i))
+ return -EFAULT;
+ if (c == 'V')
+ expect_close = 42;
+ }
+ }
+ /* Well, anyhow someone wrote to us, we should
+ return that favour */
+ acq_keepalive();
+ }
+ return count;
+}
+
+static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ int options, retval = -EINVAL;
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ static const struct watchdog_info ident = {
+ .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+ .firmware_version = 1,
+ .identity = WATCHDOG_NAME,
+ };
+
+ 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_SETOPTIONS:
+ {
+ if (get_user(options, p))
+ return -EFAULT;
+ if (options & WDIOS_DISABLECARD) {
+ acq_stop();
+ retval = 0;
+ }
+ if (options & WDIOS_ENABLECARD) {
+ acq_keepalive();
+ retval = 0;
+ }
+ return retval;
+ }
+ case WDIOC_KEEPALIVE:
+ acq_keepalive();
+ return 0;
+
+ case WDIOC_GETTIMEOUT:
+ return put_user(WATCHDOG_HEARTBEAT, p);
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+static int acq_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(0, &acq_is_open))
+ return -EBUSY;
+
+ if (nowayout)
+ __module_get(THIS_MODULE);
+
+ /* Activate */
+ acq_keepalive();
+ return nonseekable_open(inode, file);
+}
+
+static int acq_close(struct inode *inode, struct file *file)
+{
+ if (expect_close == 42) {
+ acq_stop();
+ } else {
+ pr_crit("Unexpected close, not stopping watchdog!\n");
+ acq_keepalive();
+ }
+ clear_bit(0, &acq_is_open);
+ expect_close = 0;
+ return 0;
+}
+
+/*
+ * Kernel Interfaces
+ */
+
+static const struct file_operations acq_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = acq_write,
+ .unlocked_ioctl = acq_ioctl,
+ .open = acq_open,
+ .release = acq_close,
+};
+
+static struct miscdevice acq_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &acq_fops,
+};
+
+/*
+ * Init & exit routines
+ */
+
+static int __init acq_probe(struct platform_device *dev)
+{
+ int ret;
+
+ if (wdt_stop != wdt_start) {
+ if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
+ pr_err("I/O address 0x%04x already in use\n", wdt_stop);
+ ret = -EIO;
+ goto out;
+ }
+ }
+
+ if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
+ pr_err("I/O address 0x%04x already in use\n", wdt_start);
+ ret = -EIO;
+ goto unreg_stop;
+ }
+ ret = misc_register(&acq_miscdev);
+ if (ret != 0) {
+ pr_err("cannot register miscdev on minor=%d (err=%d)\n",
+ WATCHDOG_MINOR, ret);
+ goto unreg_regions;
+ }
+ pr_info("initialized. (nowayout=%d)\n", nowayout);
+
+ return 0;
+unreg_regions:
+ release_region(wdt_start, 1);
+unreg_stop:
+ if (wdt_stop != wdt_start)
+ release_region(wdt_stop, 1);
+out:
+ return ret;
+}
+
+static int acq_remove(struct platform_device *dev)
+{
+ misc_deregister(&acq_miscdev);
+ release_region(wdt_start, 1);
+ if (wdt_stop != wdt_start)
+ release_region(wdt_stop, 1);
+
+ return 0;
+}
+
+static void acq_shutdown(struct platform_device *dev)
+{
+ /* Turn the WDT off if we have a soft shutdown */
+ acq_stop();
+}
+
+static struct platform_driver acquirewdt_driver = {
+ .remove = acq_remove,
+ .shutdown = acq_shutdown,
+ .driver = {
+ .name = DRV_NAME,
+ },
+};
+
+static int __init acq_init(void)
+{
+ int err;
+
+ pr_info("WDT driver for Acquire single board computer initialising\n");
+
+ acq_platform_device = platform_device_register_simple(DRV_NAME,
+ -1, NULL, 0);
+ if (IS_ERR(acq_platform_device))
+ return PTR_ERR(acq_platform_device);
+
+ err = platform_driver_probe(&acquirewdt_driver, acq_probe);
+ if (err)
+ goto unreg_platform_device;
+ return 0;
+
+unreg_platform_device:
+ platform_device_unregister(acq_platform_device);
+ return err;
+}
+
+static void __exit acq_exit(void)
+{
+ platform_device_unregister(acq_platform_device);
+ platform_driver_unregister(&acquirewdt_driver);
+ pr_info("Watchdog Module Unloaded\n");
+}
+
+module_init(acq_init);
+module_exit(acq_exit);
+
+MODULE_AUTHOR("David Woodhouse");
+MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff