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1// SPDX-License-Identifier: GPL-2.0+2/*3 * IB700 Single Board Computer WDT driver4 *5 * (c) Copyright 2001 Charles Howes <chowes@vsol.net>6 *7 * Based on advantechwdt.c which is based on acquirewdt.c which8 * is based on wdt.c.9 *10 * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>11 *12 * Based on acquirewdt.c which is based on wdt.c.13 * Original copyright messages:14 *15 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,16 * All Rights Reserved.17 *18 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide19 * warranty for any of this software. This material is provided20 * "AS-IS" and at no charge.21 *22 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>23 *24 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>25 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT26 * Added timeout module option to override default27 *28 */29 30#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt31 32#include <linux/module.h>33#include <linux/types.h>34#include <linux/miscdevice.h>35#include <linux/watchdog.h>36#include <linux/ioport.h>37#include <linux/fs.h>38#include <linux/init.h>39#include <linux/spinlock.h>40#include <linux/moduleparam.h>41#include <linux/platform_device.h>42#include <linux/io.h>43#include <linux/uaccess.h>44 45 46static struct platform_device *ibwdt_platform_device;47static unsigned long ibwdt_is_open;48static DEFINE_SPINLOCK(ibwdt_lock);49static char expect_close;50 51/* Module information */52#define DRV_NAME "ib700wdt"53 54/*55 *56 * Watchdog Timer Configuration57 *58 * The function of the watchdog timer is to reset the system59 * automatically and is defined at I/O port 0443H. To enable the60 * watchdog timer and allow the system to reset, write I/O port 0443H.61 * To disable the timer, write I/O port 0441H for the system to stop the62 * watchdog function. The timer has a tolerance of 20% for its63 * intervals.64 *65 * The following describes how the timer should be programmed.66 *67 * Enabling Watchdog:68 * MOV AX,000FH (Choose the values from 0 to F)69 * MOV DX,0443H70 * OUT DX,AX71 *72 * Disabling Watchdog:73 * MOV AX,000FH (Any value is fine.)74 * MOV DX,0441H75 * OUT DX,AX76 *77 * Watchdog timer control table:78 * Level Value Time/sec | Level Value Time/sec79 * 1 F 0 | 9 7 1680 * 2 E 2 | 10 6 1881 * 3 D 4 | 11 5 2082 * 4 C 6 | 12 4 2283 * 5 B 8 | 13 3 2484 * 6 A 10 | 14 2 2685 * 7 9 12 | 15 1 2886 * 8 8 14 | 16 0 3087 *88 */89 90#define WDT_STOP 0x44191#define WDT_START 0x44392 93/* Default timeout */94#define WATCHDOG_TIMEOUT 30 /* 30 seconds +/- 20% */95static int timeout = WATCHDOG_TIMEOUT; /* in seconds */96module_param(timeout, int, 0);97MODULE_PARM_DESC(timeout,98 "Watchdog timeout in seconds. 0<= timeout <=30, default="99 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");100 101static bool nowayout = WATCHDOG_NOWAYOUT;102module_param(nowayout, bool, 0);103MODULE_PARM_DESC(nowayout,104 "Watchdog cannot be stopped once started (default="105 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");106 107 108/*109 * Watchdog Operations110 */111 112static void ibwdt_ping(void)113{114 int wd_margin = 15 - ((timeout + 1) / 2);115 116 spin_lock(&ibwdt_lock);117 118 /* Write a watchdog value */119 outb_p(wd_margin, WDT_START);120 121 spin_unlock(&ibwdt_lock);122}123 124static void ibwdt_disable(void)125{126 spin_lock(&ibwdt_lock);127 outb_p(0, WDT_STOP);128 spin_unlock(&ibwdt_lock);129}130 131static int ibwdt_set_heartbeat(int t)132{133 if (t < 0 || t > 30)134 return -EINVAL;135 136 timeout = t;137 return 0;138}139 140/*141 * /dev/watchdog handling142 */143 144static ssize_t ibwdt_write(struct file *file, const char __user *buf,145 size_t count, loff_t *ppos)146{147 if (count) {148 if (!nowayout) {149 size_t i;150 151 /* In case it was set long ago */152 expect_close = 0;153 154 for (i = 0; i != count; i++) {155 char c;156 if (get_user(c, buf + i))157 return -EFAULT;158 if (c == 'V')159 expect_close = 42;160 }161 }162 ibwdt_ping();163 }164 return count;165}166 167static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)168{169 int new_margin;170 void __user *argp = (void __user *)arg;171 int __user *p = argp;172 173 static const struct watchdog_info ident = {174 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT175 | WDIOF_MAGICCLOSE,176 .firmware_version = 1,177 .identity = "IB700 WDT",178 };179 180 switch (cmd) {181 case WDIOC_GETSUPPORT:182 if (copy_to_user(argp, &ident, sizeof(ident)))183 return -EFAULT;184 break;185 186 case WDIOC_GETSTATUS:187 case WDIOC_GETBOOTSTATUS:188 return put_user(0, p);189 190 case WDIOC_SETOPTIONS:191 {192 int options, retval = -EINVAL;193 194 if (get_user(options, p))195 return -EFAULT;196 197 if (options & WDIOS_DISABLECARD) {198 ibwdt_disable();199 retval = 0;200 }201 if (options & WDIOS_ENABLECARD) {202 ibwdt_ping();203 retval = 0;204 }205 return retval;206 }207 case WDIOC_KEEPALIVE:208 ibwdt_ping();209 break;210 211 case WDIOC_SETTIMEOUT:212 if (get_user(new_margin, p))213 return -EFAULT;214 if (ibwdt_set_heartbeat(new_margin))215 return -EINVAL;216 ibwdt_ping();217 fallthrough;218 219 case WDIOC_GETTIMEOUT:220 return put_user(timeout, p);221 222 default:223 return -ENOTTY;224 }225 return 0;226}227 228static int ibwdt_open(struct inode *inode, struct file *file)229{230 if (test_and_set_bit(0, &ibwdt_is_open))231 return -EBUSY;232 if (nowayout)233 __module_get(THIS_MODULE);234 235 /* Activate */236 ibwdt_ping();237 return stream_open(inode, file);238}239 240static int ibwdt_close(struct inode *inode, struct file *file)241{242 if (expect_close == 42) {243 ibwdt_disable();244 } else {245 pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");246 ibwdt_ping();247 }248 clear_bit(0, &ibwdt_is_open);249 expect_close = 0;250 return 0;251}252 253/*254 * Kernel Interfaces255 */256 257static const struct file_operations ibwdt_fops = {258 .owner = THIS_MODULE,259 .write = ibwdt_write,260 .unlocked_ioctl = ibwdt_ioctl,261 .compat_ioctl = compat_ptr_ioctl,262 .open = ibwdt_open,263 .release = ibwdt_close,264};265 266static struct miscdevice ibwdt_miscdev = {267 .minor = WATCHDOG_MINOR,268 .name = "watchdog",269 .fops = &ibwdt_fops,270};271 272/*273 * Init & exit routines274 */275 276static int __init ibwdt_probe(struct platform_device *dev)277{278 int res;279 280#if WDT_START != WDT_STOP281 if (!request_region(WDT_STOP, 1, "IB700 WDT")) {282 pr_err("STOP method I/O %X is not available\n", WDT_STOP);283 res = -EIO;284 goto out_nostopreg;285 }286#endif287 288 if (!request_region(WDT_START, 1, "IB700 WDT")) {289 pr_err("START method I/O %X is not available\n", WDT_START);290 res = -EIO;291 goto out_nostartreg;292 }293 294 /* Check that the heartbeat value is within it's range ;295 * if not reset to the default */296 if (ibwdt_set_heartbeat(timeout)) {297 ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);298 pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);299 }300 301 res = misc_register(&ibwdt_miscdev);302 if (res) {303 pr_err("failed to register misc device\n");304 goto out_nomisc;305 }306 return 0;307 308out_nomisc:309 release_region(WDT_START, 1);310out_nostartreg:311#if WDT_START != WDT_STOP312 release_region(WDT_STOP, 1);313#endif314out_nostopreg:315 return res;316}317 318static void ibwdt_remove(struct platform_device *dev)319{320 misc_deregister(&ibwdt_miscdev);321 release_region(WDT_START, 1);322#if WDT_START != WDT_STOP323 release_region(WDT_STOP, 1);324#endif325}326 327static void ibwdt_shutdown(struct platform_device *dev)328{329 /* Turn the WDT off if we have a soft shutdown */330 ibwdt_disable();331}332 333static struct platform_driver ibwdt_driver = {334 .remove_new = ibwdt_remove,335 .shutdown = ibwdt_shutdown,336 .driver = {337 .name = DRV_NAME,338 },339};340 341static int __init ibwdt_init(void)342{343 int err;344 345 pr_info("WDT driver for IB700 single board computer initialising\n");346 347 ibwdt_platform_device = platform_device_register_simple(DRV_NAME,348 -1, NULL, 0);349 if (IS_ERR(ibwdt_platform_device))350 return PTR_ERR(ibwdt_platform_device);351 352 err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);353 if (err)354 goto unreg_platform_device;355 356 return 0;357 358unreg_platform_device:359 platform_device_unregister(ibwdt_platform_device);360 return err;361}362 363static void __exit ibwdt_exit(void)364{365 platform_device_unregister(ibwdt_platform_device);366 platform_driver_unregister(&ibwdt_driver);367 pr_info("Watchdog Module Unloaded\n");368}369 370module_init(ibwdt_init);371module_exit(ibwdt_exit);372 373MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");374MODULE_DESCRIPTION("IB700 SBC watchdog driver");375MODULE_LICENSE("GPL");376 377/* end of ib700wdt.c */378