drivers/watchdog/w83877f_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  W83877F Computer Watchdog Timer driver
0004  *
0005  *      Based on acquirewdt.c by Alan Cox,
0006  *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
0007  *
0008  *  The authors do NOT admit liability nor provide warranty for
0009  *  any of this software. This material is provided "AS-IS" in
0010  *      the hope that it may be useful for others.
0011  *
0012  *  (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
0013  *
0014  *           4/19 - 2001      [Initial revision]
0015  *           9/27 - 2001      Added spinlocking
0016  *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
0017  *                            Eliminate fop_read
0018  *                            Eliminate extra spin_unlock
0019  *                            Added KERN_* tags to printks
0020  *                            add CONFIG_WATCHDOG_NOWAYOUT support
0021  *                            fix possible wdt_is_open race
0022  *                            changed watchdog_info to correctly reflect what
0023  *                the driver offers
0024  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
0025  *                WDIOC_SETTIMEOUT,
0026  *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
0027  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
0028  *                            added extra printk's for startup problems
0029  *                            use module_param
0030  *                            made timeout (the emulated heartbeat) a
0031  *                module_param
0032  *                            made the keepalive ping an internal subroutine
0033  *
0034  *  This WDT driver is different from most other Linux WDT
0035  *  drivers in that the driver will ping the watchdog by itself,
0036  *  because this particular WDT has a very short timeout (1.6
0037  *  seconds) and it would be insane to count on any userspace
0038  *  daemon always getting scheduled within that time frame.
0039  */
0040
0041 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0042
0043 #include <linux/module.h>
0044 #include <linux/moduleparam.h>
0045 #include <linux/types.h>
0046 #include <linux/timer.h>
0047 #include <linux/jiffies.h>
0048 #include <linux/miscdevice.h>
0049 #include <linux/watchdog.h>
0050 #include <linux/fs.h>
0051 #include <linux/ioport.h>
0052 #include <linux/notifier.h>
0053 #include <linux/reboot.h>
0054 #include <linux/init.h>
0055 #include <linux/io.h>
0056 #include <linux/uaccess.h>
0057
0058 #define OUR_NAME "w83877f_wdt"
0059
0060 #define ENABLE_W83877F_PORT 0x3F0
0061 #define ENABLE_W83877F 0x87
0062 #define DISABLE_W83877F 0xAA
0063 #define WDT_PING 0x443
0064 #define WDT_REGISTER 0x14
0065 #define WDT_ENABLE 0x9C
0066 #define WDT_DISABLE 0x8C
0067
0068 /*
0069  * The W83877F seems to be fixed at 1.6s timeout (at least on the
0070  * EMACS PC-104 board I'm using). If we reset the watchdog every
0071  * ~250ms we should be safe.  */
0072
0073 #define WDT_INTERVAL (HZ/4+1)
0074
0075 /*
0076  * We must not require too good response from the userspace daemon.
0077  * Here we require the userspace daemon to send us a heartbeat
0078  * char to /dev/watchdog every 30 seconds.
0079  */
0080
0081 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
0082 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
0083 static int timeout = WATCHDOG_TIMEOUT;
0084 module_param(timeout, int, 0);
0085 MODULE_PARM_DESC(timeout,
0086     "Watchdog timeout in seconds. (1<=timeout<=3600, default="
0087                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
0088
0089
0090 static bool nowayout = WATCHDOG_NOWAYOUT;
0091 module_param(nowayout, bool, 0);
0092 MODULE_PARM_DESC(nowayout,
0093         "Watchdog cannot be stopped once started (default="
0094                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0095
0096 static void wdt_timer_ping(struct timer_list *);
0097 static DEFINE_TIMER(timer, wdt_timer_ping);
0098 static unsigned long next_heartbeat;
0099 static unsigned long wdt_is_open;
0100 static char wdt_expect_close;
0101 static DEFINE_SPINLOCK(wdt_spinlock);
0102
0103 /*
0104  *  Whack the dog
0105  */
0106
0107 static void wdt_timer_ping(struct timer_list *unused)
0108 {
0109     /* If we got a heartbeat pulse within the WDT_US_INTERVAL
0110      * we agree to ping the WDT
0111      */
0112     if (time_before(jiffies, next_heartbeat)) {
0113         /* Ping the WDT */
0114         spin_lock(&wdt_spinlock);
0115
0116         /* Ping the WDT by reading from WDT_PING */
0117         inb_p(WDT_PING);
0118
0119         /* Re-set the timer interval */
0120         mod_timer(&timer, jiffies + WDT_INTERVAL);
0121
0122         spin_unlock(&wdt_spinlock);
0123
0124     } else
0125         pr_warn("Heartbeat lost! Will not ping the watchdog\n");
0126 }
0127
0128 /*
0129  * Utility routines
0130  */
0131
0132 static void wdt_change(int writeval)
0133 {
0134     unsigned long flags;
0135     spin_lock_irqsave(&wdt_spinlock, flags);
0136
0137     /* buy some time */
0138     inb_p(WDT_PING);
0139
0140     /* make W83877F available */
0141     outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
0142     outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
0143
0144     /* enable watchdog */
0145     outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
0146     outb_p(writeval,        ENABLE_W83877F_PORT+1);
0147
0148     /* lock the W8387FF away */
0149     outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
0150
0151     spin_unlock_irqrestore(&wdt_spinlock, flags);
0152 }
0153
0154 static void wdt_startup(void)
0155 {
0156     next_heartbeat = jiffies + (timeout * HZ);
0157
0158     /* Start the timer */
0159     mod_timer(&timer, jiffies + WDT_INTERVAL);
0160
0161     wdt_change(WDT_ENABLE);
0162
0163     pr_info("Watchdog timer is now enabled\n");
0164 }
0165
0166 static void wdt_turnoff(void)
0167 {
0168     /* Stop the timer */
0169     del_timer_sync(&timer);
0170
0171     wdt_change(WDT_DISABLE);
0172
0173     pr_info("Watchdog timer is now disabled...\n");
0174 }
0175
0176 static void wdt_keepalive(void)
0177 {
0178     /* user land ping */
0179     next_heartbeat = jiffies + (timeout * HZ);
0180 }
0181
0182 /*
0183  * /dev/watchdog handling
0184  */
0185
0186 static ssize_t fop_write(struct file *file, const char __user *buf,
0187                         size_t count, loff_t *ppos)
0188 {
0189     /* See if we got the magic character 'V' and reload the timer */
0190     if (count) {
0191         if (!nowayout) {
0192             size_t ofs;
0193
0194             /* note: just in case someone wrote the magic
0195                character five months ago... */
0196             wdt_expect_close = 0;
0197
0198             /* scan to see whether or not we got the
0199                magic character */
0200             for (ofs = 0; ofs != count; ofs++) {
0201                 char c;
0202                 if (get_user(c, buf + ofs))
0203                     return -EFAULT;
0204                 if (c == 'V')
0205                     wdt_expect_close = 42;
0206             }
0207         }
0208
0209         /* someone wrote to us, we should restart timer */
0210         wdt_keepalive();
0211     }
0212     return count;
0213 }
0214
0215 static int fop_open(struct inode *inode, struct file *file)
0216 {
0217     /* Just in case we're already talking to someone... */
0218     if (test_and_set_bit(0, &wdt_is_open))
0219         return -EBUSY;
0220
0221     /* Good, fire up the show */
0222     wdt_startup();
0223     return stream_open(inode, file);
0224 }
0225
0226 static int fop_close(struct inode *inode, struct file *file)
0227 {
0228     if (wdt_expect_close == 42)
0229         wdt_turnoff();
0230     else {
0231         del_timer(&timer);
0232         pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
0233     }
0234     clear_bit(0, &wdt_is_open);
0235     wdt_expect_close = 0;
0236     return 0;
0237 }
0238
0239 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0240 {
0241     void __user *argp = (void __user *)arg;
0242     int __user *p = argp;
0243     static const struct watchdog_info ident = {
0244         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
0245                             | WDIOF_MAGICCLOSE,
0246         .firmware_version = 1,
0247         .identity = "W83877F",
0248     };
0249
0250     switch (cmd) {
0251     case WDIOC_GETSUPPORT:
0252         return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
0253     case WDIOC_GETSTATUS:
0254     case WDIOC_GETBOOTSTATUS:
0255         return put_user(0, p);
0256     case WDIOC_SETOPTIONS:
0257     {
0258         int new_options, retval = -EINVAL;
0259
0260         if (get_user(new_options, p))
0261             return -EFAULT;
0262
0263         if (new_options & WDIOS_DISABLECARD) {
0264             wdt_turnoff();
0265             retval = 0;
0266         }
0267
0268         if (new_options & WDIOS_ENABLECARD) {
0269             wdt_startup();
0270             retval = 0;
0271         }
0272
0273         return retval;
0274     }
0275     case WDIOC_KEEPALIVE:
0276         wdt_keepalive();
0277         return 0;
0278     case WDIOC_SETTIMEOUT:
0279     {
0280         int new_timeout;
0281
0282         if (get_user(new_timeout, p))
0283             return -EFAULT;
0284
0285         /* arbitrary upper limit */
0286         if (new_timeout < 1 || new_timeout > 3600)
0287             return -EINVAL;
0288
0289         timeout = new_timeout;
0290         wdt_keepalive();
0291     }
0292         fallthrough;
0293     case WDIOC_GETTIMEOUT:
0294         return put_user(timeout, p);
0295     default:
0296         return -ENOTTY;
0297     }
0298 }
0299
0300 static const struct file_operations wdt_fops = {
0301     .owner      = THIS_MODULE,
0302     .llseek     = no_llseek,
0303     .write      = fop_write,
0304     .open       = fop_open,
0305     .release    = fop_close,
0306     .unlocked_ioctl = fop_ioctl,
0307     .compat_ioctl   = compat_ptr_ioctl,
0308 };
0309
0310 static struct miscdevice wdt_miscdev = {
0311     .minor  = WATCHDOG_MINOR,
0312     .name   = "watchdog",
0313     .fops   = &wdt_fops,
0314 };
0315
0316 /*
0317  *  Notifier for system down
0318  */
0319
0320 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
0321     void *unused)
0322 {
0323     if (code == SYS_DOWN || code == SYS_HALT)
0324         wdt_turnoff();
0325     return NOTIFY_DONE;
0326 }
0327
0328 /*
0329  *  The WDT needs to learn about soft shutdowns in order to
0330  *  turn the timebomb registers off.
0331  */
0332
0333 static struct notifier_block wdt_notifier = {
0334     .notifier_call = wdt_notify_sys,
0335 };
0336
0337 static void __exit w83877f_wdt_unload(void)
0338 {
0339     wdt_turnoff();
0340
0341     /* Deregister */
0342     misc_deregister(&wdt_miscdev);
0343
0344     unregister_reboot_notifier(&wdt_notifier);
0345     release_region(WDT_PING, 1);
0346     release_region(ENABLE_W83877F_PORT, 2);
0347 }
0348
0349 static int __init w83877f_wdt_init(void)
0350 {
0351     int rc = -EBUSY;
0352
0353     if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
0354         timeout = WATCHDOG_TIMEOUT;
0355         pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
0356             timeout);
0357     }
0358
0359     if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
0360         pr_err("I/O address 0x%04x already in use\n",
0361                ENABLE_W83877F_PORT);
0362         rc = -EIO;
0363         goto err_out;
0364     }
0365
0366     if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
0367         pr_err("I/O address 0x%04x already in use\n", WDT_PING);
0368         rc = -EIO;
0369         goto err_out_region1;
0370     }
0371
0372     rc = register_reboot_notifier(&wdt_notifier);
0373     if (rc) {
0374         pr_err("cannot register reboot notifier (err=%d)\n", rc);
0375         goto err_out_region2;
0376     }
0377
0378     rc = misc_register(&wdt_miscdev);
0379     if (rc) {
0380         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
0381                wdt_miscdev.minor, rc);
0382         goto err_out_reboot;
0383     }
0384
0385     pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
0386         timeout, nowayout);
0387
0388     return 0;
0389
0390 err_out_reboot:
0391     unregister_reboot_notifier(&wdt_notifier);
0392 err_out_region2:
0393     release_region(WDT_PING, 1);
0394 err_out_region1:
0395     release_region(ENABLE_W83877F_PORT, 2);
0396 err_out:
0397     return rc;
0398 }
0399
0400 module_init(w83877f_wdt_init);
0401 module_exit(w83877f_wdt_unload);
0402
0403 MODULE_AUTHOR("Scott and Bill Jennings");
0404 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
0405 MODULE_LICENSE("GPL");