329 lines · c
1// SPDX-License-Identifier: GPL-2.0+2/*3 * Acquire Single Board Computer Watchdog Timer driver4 *5 * Based on wdt.c. Original copyright messages:6 *7 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,8 * All Rights Reserved.9 *10 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide11 * warranty for any of this software. This material is provided12 * "AS-IS" and at no charge.13 *14 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>15 *16 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>17 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT18 * Can't add timeout - driver doesn't allow changing value19 */20 21/*22 * Theory of Operation:23 * The Watch-Dog Timer is provided to ensure that standalone24 * Systems can always recover from catastrophic conditions that25 * caused the CPU to crash. This condition may have occurred by26 * external EMI or a software bug. When the CPU stops working27 * correctly, hardware on the board will either perform a hardware28 * reset (cold boot) or a non-maskable interrupt (NMI) to bring the29 * system back to a known state.30 *31 * The Watch-Dog Timer is controlled by two I/O Ports.32 * 443 hex - Read - Enable or refresh the Watch-Dog Timer33 * 043 hex - Read - Disable the Watch-Dog Timer34 *35 * To enable the Watch-Dog Timer, a read from I/O port 443h must36 * be performed. This will enable and activate the countdown timer37 * which will eventually time out and either reset the CPU or cause38 * an NMI depending on the setting of a jumper. To ensure that this39 * reset condition does not occur, the Watch-Dog Timer must be40 * periodically refreshed by reading the same I/O port 443h.41 * The Watch-Dog Timer is disabled by reading I/O port 043h.42 *43 * The Watch-Dog Timer Time-Out Period is set via jumpers.44 * It can be 1, 2, 10, 20, 110 or 220 seconds.45 */46 47/*48 * Includes, defines, variables, module parameters, ...49 */50 51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt52 53/* Includes */54#include <linux/module.h> /* For module specific items */55#include <linux/moduleparam.h> /* For new moduleparam's */56#include <linux/types.h> /* For standard types (like size_t) */57#include <linux/errno.h> /* For the -ENODEV/... values */58#include <linux/kernel.h> /* For printk/panic/... */59#include <linux/miscdevice.h> /* For struct miscdevice */60#include <linux/watchdog.h> /* For the watchdog specific items */61#include <linux/fs.h> /* For file operations */62#include <linux/ioport.h> /* For io-port access */63#include <linux/platform_device.h> /* For platform_driver framework */64#include <linux/init.h> /* For __init/__exit/... */65#include <linux/uaccess.h> /* For copy_to_user/put_user/... */66#include <linux/io.h> /* For inb/outb/... */67 68/* Module information */69#define DRV_NAME "acquirewdt"70#define WATCHDOG_NAME "Acquire WDT"71/* There is no way to see what the correct time-out period is */72#define WATCHDOG_HEARTBEAT 073 74/* internal variables */75/* the watchdog platform device */76static struct platform_device *acq_platform_device;77static unsigned long acq_is_open;78static char expect_close;79 80/* module parameters */81/* You must set this - there is no sane way to probe for this board. */82static int wdt_stop = 0x43;83module_param(wdt_stop, int, 0);84MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");85 86/* You must set this - there is no sane way to probe for this board. */87static int wdt_start = 0x443;88module_param(wdt_start, int, 0);89MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");90 91static bool nowayout = WATCHDOG_NOWAYOUT;92module_param(nowayout, bool, 0);93MODULE_PARM_DESC(nowayout,94 "Watchdog cannot be stopped once started (default="95 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");96 97/*98 * Watchdog Operations99 */100 101static void acq_keepalive(void)102{103 /* Write a watchdog value */104 inb_p(wdt_start);105}106 107static void acq_stop(void)108{109 /* Turn the card off */110 inb_p(wdt_stop);111}112 113/*114 * /dev/watchdog handling115 */116 117static ssize_t acq_write(struct file *file, const char __user *buf,118 size_t count, loff_t *ppos)119{120 /* See if we got the magic character 'V' and reload the timer */121 if (count) {122 if (!nowayout) {123 size_t i;124 /* note: just in case someone wrote the magic character125 five months ago... */126 expect_close = 0;127 /* scan to see whether or not we got the128 magic character */129 for (i = 0; i != count; i++) {130 char c;131 if (get_user(c, buf + i))132 return -EFAULT;133 if (c == 'V')134 expect_close = 42;135 }136 }137 /* Well, anyhow someone wrote to us, we should138 return that favour */139 acq_keepalive();140 }141 return count;142}143 144static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)145{146 int options, retval = -EINVAL;147 void __user *argp = (void __user *)arg;148 int __user *p = argp;149 static const struct watchdog_info ident = {150 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,151 .firmware_version = 1,152 .identity = WATCHDOG_NAME,153 };154 155 switch (cmd) {156 case WDIOC_GETSUPPORT:157 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;158 159 case WDIOC_GETSTATUS:160 case WDIOC_GETBOOTSTATUS:161 return put_user(0, p);162 163 case WDIOC_SETOPTIONS:164 {165 if (get_user(options, p))166 return -EFAULT;167 if (options & WDIOS_DISABLECARD) {168 acq_stop();169 retval = 0;170 }171 if (options & WDIOS_ENABLECARD) {172 acq_keepalive();173 retval = 0;174 }175 return retval;176 }177 case WDIOC_KEEPALIVE:178 acq_keepalive();179 return 0;180 181 case WDIOC_GETTIMEOUT:182 return put_user(WATCHDOG_HEARTBEAT, p);183 184 default:185 return -ENOTTY;186 }187}188 189static int acq_open(struct inode *inode, struct file *file)190{191 if (test_and_set_bit(0, &acq_is_open))192 return -EBUSY;193 194 if (nowayout)195 __module_get(THIS_MODULE);196 197 /* Activate */198 acq_keepalive();199 return stream_open(inode, file);200}201 202static int acq_close(struct inode *inode, struct file *file)203{204 if (expect_close == 42) {205 acq_stop();206 } else {207 pr_crit("Unexpected close, not stopping watchdog!\n");208 acq_keepalive();209 }210 clear_bit(0, &acq_is_open);211 expect_close = 0;212 return 0;213}214 215/*216 * Kernel Interfaces217 */218 219static const struct file_operations acq_fops = {220 .owner = THIS_MODULE,221 .write = acq_write,222 .unlocked_ioctl = acq_ioctl,223 .compat_ioctl = compat_ptr_ioctl,224 .open = acq_open,225 .release = acq_close,226};227 228static struct miscdevice acq_miscdev = {229 .minor = WATCHDOG_MINOR,230 .name = "watchdog",231 .fops = &acq_fops,232};233 234/*235 * Init & exit routines236 */237 238static int __init acq_probe(struct platform_device *dev)239{240 int ret;241 242 if (wdt_stop != wdt_start) {243 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {244 pr_err("I/O address 0x%04x already in use\n", wdt_stop);245 ret = -EIO;246 goto out;247 }248 }249 250 if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {251 pr_err("I/O address 0x%04x already in use\n", wdt_start);252 ret = -EIO;253 goto unreg_stop;254 }255 ret = misc_register(&acq_miscdev);256 if (ret != 0) {257 pr_err("cannot register miscdev on minor=%d (err=%d)\n",258 WATCHDOG_MINOR, ret);259 goto unreg_regions;260 }261 pr_info("initialized. (nowayout=%d)\n", nowayout);262 263 return 0;264unreg_regions:265 release_region(wdt_start, 1);266unreg_stop:267 if (wdt_stop != wdt_start)268 release_region(wdt_stop, 1);269out:270 return ret;271}272 273static void acq_remove(struct platform_device *dev)274{275 misc_deregister(&acq_miscdev);276 release_region(wdt_start, 1);277 if (wdt_stop != wdt_start)278 release_region(wdt_stop, 1);279}280 281static void acq_shutdown(struct platform_device *dev)282{283 /* Turn the WDT off if we have a soft shutdown */284 acq_stop();285}286 287static struct platform_driver acquirewdt_driver = {288 .remove_new = acq_remove,289 .shutdown = acq_shutdown,290 .driver = {291 .name = DRV_NAME,292 },293};294 295static int __init acq_init(void)296{297 int err;298 299 pr_info("WDT driver for Acquire single board computer initialising\n");300 301 acq_platform_device = platform_device_register_simple(DRV_NAME,302 -1, NULL, 0);303 if (IS_ERR(acq_platform_device))304 return PTR_ERR(acq_platform_device);305 306 err = platform_driver_probe(&acquirewdt_driver, acq_probe);307 if (err)308 goto unreg_platform_device;309 return 0;310 311unreg_platform_device:312 platform_device_unregister(acq_platform_device);313 return err;314}315 316static void __exit acq_exit(void)317{318 platform_device_unregister(acq_platform_device);319 platform_driver_unregister(&acquirewdt_driver);320 pr_info("Watchdog Module Unloaded\n");321}322 323module_init(acq_init);324module_exit(acq_exit);325 326MODULE_AUTHOR("David Woodhouse");327MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");328MODULE_LICENSE("GPL");329