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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * W83877F Computer Watchdog Timer driver4 *5 * Based on acquirewdt.c by Alan Cox,6 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>7 *8 * The authors do NOT admit liability nor provide warranty for9 * any of this software. This material is provided "AS-IS" in10 * the hope that it may be useful for others.11 *12 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>13 *14 * 4/19 - 2001 [Initial revision]15 * 9/27 - 2001 Added spinlocking16 * 4/12 - 2002 [rob@osinvestor.com] Eliminate extra comments17 * Eliminate fop_read18 * Eliminate extra spin_unlock19 * Added KERN_* tags to printks20 * add CONFIG_WATCHDOG_NOWAYOUT support21 * fix possible wdt_is_open race22 * changed watchdog_info to correctly reflect what23 * the driver offers24 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,25 * WDIOC_SETTIMEOUT,26 * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls27 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces28 * added extra printk's for startup problems29 * use module_param30 * made timeout (the emulated heartbeat) a31 * module_param32 * made the keepalive ping an internal subroutine33 *34 * This WDT driver is different from most other Linux WDT35 * drivers in that the driver will ping the watchdog by itself,36 * because this particular WDT has a very short timeout (1.637 * seconds) and it would be insane to count on any userspace38 * daemon always getting scheduled within that time frame.39 */40 41#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt42 43#include <linux/module.h>44#include <linux/moduleparam.h>45#include <linux/types.h>46#include <linux/timer.h>47#include <linux/jiffies.h>48#include <linux/miscdevice.h>49#include <linux/watchdog.h>50#include <linux/fs.h>51#include <linux/ioport.h>52#include <linux/notifier.h>53#include <linux/reboot.h>54#include <linux/init.h>55#include <linux/io.h>56#include <linux/uaccess.h>57 58#define OUR_NAME "w83877f_wdt"59 60#define ENABLE_W83877F_PORT 0x3F061#define ENABLE_W83877F 0x8762#define DISABLE_W83877F 0xAA63#define WDT_PING 0x44364#define WDT_REGISTER 0x1465#define WDT_ENABLE 0x9C66#define WDT_DISABLE 0x8C67 68/*69 * The W83877F seems to be fixed at 1.6s timeout (at least on the70 * EMACS PC-104 board I'm using). If we reset the watchdog every71 * ~250ms we should be safe. */72 73#define WDT_INTERVAL (HZ/4+1)74 75/*76 * We must not require too good response from the userspace daemon.77 * Here we require the userspace daemon to send us a heartbeat78 * char to /dev/watchdog every 30 seconds.79 */80 81#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */82/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */83static int timeout = WATCHDOG_TIMEOUT;84module_param(timeout, int, 0);85MODULE_PARM_DESC(timeout,86 "Watchdog timeout in seconds. (1<=timeout<=3600, default="87 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");88 89 90static bool nowayout = WATCHDOG_NOWAYOUT;91module_param(nowayout, bool, 0);92MODULE_PARM_DESC(nowayout,93 "Watchdog cannot be stopped once started (default="94 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");95 96static void wdt_timer_ping(struct timer_list *);97static DEFINE_TIMER(timer, wdt_timer_ping);98static unsigned long next_heartbeat;99static unsigned long wdt_is_open;100static char wdt_expect_close;101static DEFINE_SPINLOCK(wdt_spinlock);102 103/*104 * Whack the dog105 */106 107static void wdt_timer_ping(struct timer_list *unused)108{109 /* If we got a heartbeat pulse within the WDT_US_INTERVAL110 * we agree to ping the WDT111 */112 if (time_before(jiffies, next_heartbeat)) {113 /* Ping the WDT */114 spin_lock(&wdt_spinlock);115 116 /* Ping the WDT by reading from WDT_PING */117 inb_p(WDT_PING);118 119 /* Re-set the timer interval */120 mod_timer(&timer, jiffies + WDT_INTERVAL);121 122 spin_unlock(&wdt_spinlock);123 124 } else125 pr_warn("Heartbeat lost! Will not ping the watchdog\n");126}127 128/*129 * Utility routines130 */131 132static void wdt_change(int writeval)133{134 unsigned long flags;135 spin_lock_irqsave(&wdt_spinlock, flags);136 137 /* buy some time */138 inb_p(WDT_PING);139 140 /* make W83877F available */141 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);142 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);143 144 /* enable watchdog */145 outb_p(WDT_REGISTER, ENABLE_W83877F_PORT);146 outb_p(writeval, ENABLE_W83877F_PORT+1);147 148 /* lock the W8387FF away */149 outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);150 151 spin_unlock_irqrestore(&wdt_spinlock, flags);152}153 154static void wdt_startup(void)155{156 next_heartbeat = jiffies + (timeout * HZ);157 158 /* Start the timer */159 mod_timer(&timer, jiffies + WDT_INTERVAL);160 161 wdt_change(WDT_ENABLE);162 163 pr_info("Watchdog timer is now enabled\n");164}165 166static void wdt_turnoff(void)167{168 /* Stop the timer */169 del_timer_sync(&timer);170 171 wdt_change(WDT_DISABLE);172 173 pr_info("Watchdog timer is now disabled...\n");174}175 176static void wdt_keepalive(void)177{178 /* user land ping */179 next_heartbeat = jiffies + (timeout * HZ);180}181 182/*183 * /dev/watchdog handling184 */185 186static ssize_t fop_write(struct file *file, const char __user *buf,187 size_t count, loff_t *ppos)188{189 /* See if we got the magic character 'V' and reload the timer */190 if (count) {191 if (!nowayout) {192 size_t ofs;193 194 /* note: just in case someone wrote the magic195 character five months ago... */196 wdt_expect_close = 0;197 198 /* scan to see whether or not we got the199 magic character */200 for (ofs = 0; ofs != count; ofs++) {201 char c;202 if (get_user(c, buf + ofs))203 return -EFAULT;204 if (c == 'V')205 wdt_expect_close = 42;206 }207 }208 209 /* someone wrote to us, we should restart timer */210 wdt_keepalive();211 }212 return count;213}214 215static int fop_open(struct inode *inode, struct file *file)216{217 /* Just in case we're already talking to someone... */218 if (test_and_set_bit(0, &wdt_is_open))219 return -EBUSY;220 221 /* Good, fire up the show */222 wdt_startup();223 return stream_open(inode, file);224}225 226static int fop_close(struct inode *inode, struct file *file)227{228 if (wdt_expect_close == 42)229 wdt_turnoff();230 else {231 del_timer(&timer);232 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");233 }234 clear_bit(0, &wdt_is_open);235 wdt_expect_close = 0;236 return 0;237}238 239static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)240{241 void __user *argp = (void __user *)arg;242 int __user *p = argp;243 static const struct watchdog_info ident = {244 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT245 | WDIOF_MAGICCLOSE,246 .firmware_version = 1,247 .identity = "W83877F",248 };249 250 switch (cmd) {251 case WDIOC_GETSUPPORT:252 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;253 case WDIOC_GETSTATUS:254 case WDIOC_GETBOOTSTATUS:255 return put_user(0, p);256 case WDIOC_SETOPTIONS:257 {258 int new_options, retval = -EINVAL;259 260 if (get_user(new_options, p))261 return -EFAULT;262 263 if (new_options & WDIOS_DISABLECARD) {264 wdt_turnoff();265 retval = 0;266 }267 268 if (new_options & WDIOS_ENABLECARD) {269 wdt_startup();270 retval = 0;271 }272 273 return retval;274 }275 case WDIOC_KEEPALIVE:276 wdt_keepalive();277 return 0;278 case WDIOC_SETTIMEOUT:279 {280 int new_timeout;281 282 if (get_user(new_timeout, p))283 return -EFAULT;284 285 /* arbitrary upper limit */286 if (new_timeout < 1 || new_timeout > 3600)287 return -EINVAL;288 289 timeout = new_timeout;290 wdt_keepalive();291 }292 fallthrough;293 case WDIOC_GETTIMEOUT:294 return put_user(timeout, p);295 default:296 return -ENOTTY;297 }298}299 300static const struct file_operations wdt_fops = {301 .owner = THIS_MODULE,302 .write = fop_write,303 .open = fop_open,304 .release = fop_close,305 .unlocked_ioctl = fop_ioctl,306 .compat_ioctl = compat_ptr_ioctl,307};308 309static struct miscdevice wdt_miscdev = {310 .minor = WATCHDOG_MINOR,311 .name = "watchdog",312 .fops = &wdt_fops,313};314 315/*316 * Notifier for system down317 */318 319static int wdt_notify_sys(struct notifier_block *this, unsigned long code,320 void *unused)321{322 if (code == SYS_DOWN || code == SYS_HALT)323 wdt_turnoff();324 return NOTIFY_DONE;325}326 327/*328 * The WDT needs to learn about soft shutdowns in order to329 * turn the timebomb registers off.330 */331 332static struct notifier_block wdt_notifier = {333 .notifier_call = wdt_notify_sys,334};335 336static void __exit w83877f_wdt_unload(void)337{338 wdt_turnoff();339 340 /* Deregister */341 misc_deregister(&wdt_miscdev);342 343 unregister_reboot_notifier(&wdt_notifier);344 release_region(WDT_PING, 1);345 release_region(ENABLE_W83877F_PORT, 2);346}347 348static int __init w83877f_wdt_init(void)349{350 int rc = -EBUSY;351 352 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */353 timeout = WATCHDOG_TIMEOUT;354 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",355 timeout);356 }357 358 if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {359 pr_err("I/O address 0x%04x already in use\n",360 ENABLE_W83877F_PORT);361 rc = -EIO;362 goto err_out;363 }364 365 if (!request_region(WDT_PING, 1, "W8387FF WDT")) {366 pr_err("I/O address 0x%04x already in use\n", WDT_PING);367 rc = -EIO;368 goto err_out_region1;369 }370 371 rc = register_reboot_notifier(&wdt_notifier);372 if (rc) {373 pr_err("cannot register reboot notifier (err=%d)\n", rc);374 goto err_out_region2;375 }376 377 rc = misc_register(&wdt_miscdev);378 if (rc) {379 pr_err("cannot register miscdev on minor=%d (err=%d)\n",380 wdt_miscdev.minor, rc);381 goto err_out_reboot;382 }383 384 pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",385 timeout, nowayout);386 387 return 0;388 389err_out_reboot:390 unregister_reboot_notifier(&wdt_notifier);391err_out_region2:392 release_region(WDT_PING, 1);393err_out_region1:394 release_region(ENABLE_W83877F_PORT, 2);395err_out:396 return rc;397}398 399module_init(w83877f_wdt_init);400module_exit(w83877f_wdt_unload);401 402MODULE_AUTHOR("Scott and Bill Jennings");403MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");404MODULE_LICENSE("GPL");405