drivers/watchdog/sbc60xxwdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
0004  *
0005  *  Based on acquirewdt.c by Alan Cox.
0006  *
0007  *  The author does NOT admit liability nor provide warranty for
0008  *  any of this software. This material is provided "AS-IS" in
0009  *  the hope that it may be useful for others.
0010  *
0011  *  (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
0012  *
0013  *           12/4 - 2000      [Initial revision]
0014  *           25/4 - 2000      Added /dev/watchdog support
0015  *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
0016  *                  on success
0017  *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
0018  *                            fix possible wdt_is_open race
0019  *                            add CONFIG_WATCHDOG_NOWAYOUT support
0020  *                            remove lock_kernel/unlock_kernel pairs
0021  *                            added KERN_* to printk's
0022  *                            got rid of extraneous comments
0023  *                            changed watchdog_info to correctly reflect what
0024  *                the driver offers
0025  *                added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
0026  *                WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
0027  *                WDIOC_SETOPTIONS ioctls
0028  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
0029  *                            use module_param
0030  *                            made timeout (the emulated heartbeat) a
0031  *                module_param
0032  *                            made the keepalive ping an internal subroutine
0033  *                            made wdt_stop and wdt_start module params
0034  *                            added extra printk's for startup problems
0035  *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
0036  *
0037  *  This WDT driver is different from the other Linux WDT
0038  *  drivers in the following ways:
0039  *  *)  The driver will ping the watchdog by itself, because this
0040  *      particular WDT has a very short timeout (one second) and it
0041  *      would be insane to count on any userspace daemon always
0042  *      getting scheduled within that time frame.
0043  */
0044
0045 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0046
0047 #include <linux/module.h>
0048 #include <linux/moduleparam.h>
0049 #include <linux/types.h>
0050 #include <linux/timer.h>
0051 #include <linux/jiffies.h>
0052 #include <linux/miscdevice.h>
0053 #include <linux/watchdog.h>
0054 #include <linux/fs.h>
0055 #include <linux/ioport.h>
0056 #include <linux/notifier.h>
0057 #include <linux/reboot.h>
0058 #include <linux/init.h>
0059 #include <linux/io.h>
0060 #include <linux/uaccess.h>
0061
0062
0063 #define OUR_NAME "sbc60xxwdt"
0064 #define PFX OUR_NAME ": "
0065
0066 /*
0067  * You must set these - The driver cannot probe for the settings
0068  */
0069
0070 static int wdt_stop = 0x45;
0071 module_param(wdt_stop, int, 0);
0072 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
0073
0074 static int wdt_start = 0x443;
0075 module_param(wdt_start, int, 0);
0076 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
0077
0078 /*
0079  * The 60xx board can use watchdog timeout values from one second
0080  * to several minutes.  The default is one second, so if we reset
0081  * the watchdog every ~250ms we should be safe.
0082  */
0083
0084 #define WDT_INTERVAL (HZ/4+1)
0085
0086 /*
0087  * We must not require too good response from the userspace daemon.
0088  * Here we require the userspace daemon to send us a heartbeat
0089  * char to /dev/watchdog every 30 seconds.
0090  * If the daemon pulses us every 25 seconds, we can still afford
0091  * a 5 second scheduling delay on the (high priority) daemon. That
0092  * should be sufficient for a box under any load.
0093  */
0094
0095 #define WATCHDOG_TIMEOUT 30     /* 30 sec default timeout */
0096 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
0097                        get seconds to wait for a ping */
0098 module_param(timeout, int, 0);
0099 MODULE_PARM_DESC(timeout,
0100     "Watchdog timeout in seconds. (1<=timeout<=3600, default="
0101                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
0102
0103 static bool nowayout = WATCHDOG_NOWAYOUT;
0104 module_param(nowayout, bool, 0);
0105 MODULE_PARM_DESC(nowayout,
0106     "Watchdog cannot be stopped once started (default="
0107                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0108
0109 static void wdt_timer_ping(struct timer_list *);
0110 static DEFINE_TIMER(timer, wdt_timer_ping);
0111 static unsigned long next_heartbeat;
0112 static unsigned long wdt_is_open;
0113 static char wdt_expect_close;
0114
0115 /*
0116  *  Whack the dog
0117  */
0118
0119 static void wdt_timer_ping(struct timer_list *unused)
0120 {
0121     /* If we got a heartbeat pulse within the WDT_US_INTERVAL
0122      * we agree to ping the WDT
0123      */
0124     if (time_before(jiffies, next_heartbeat)) {
0125         /* Ping the WDT by reading from wdt_start */
0126         inb_p(wdt_start);
0127         /* Re-set the timer interval */
0128         mod_timer(&timer, jiffies + WDT_INTERVAL);
0129     } else
0130         pr_warn("Heartbeat lost! Will not ping the watchdog\n");
0131 }
0132
0133 /*
0134  * Utility routines
0135  */
0136
0137 static void wdt_startup(void)
0138 {
0139     next_heartbeat = jiffies + (timeout * HZ);
0140
0141     /* Start the timer */
0142     mod_timer(&timer, jiffies + WDT_INTERVAL);
0143     pr_info("Watchdog timer is now enabled\n");
0144 }
0145
0146 static void wdt_turnoff(void)
0147 {
0148     /* Stop the timer */
0149     del_timer_sync(&timer);
0150     inb_p(wdt_stop);
0151     pr_info("Watchdog timer is now disabled...\n");
0152 }
0153
0154 static void wdt_keepalive(void)
0155 {
0156     /* user land ping */
0157     next_heartbeat = jiffies + (timeout * HZ);
0158 }
0159
0160 /*
0161  * /dev/watchdog handling
0162  */
0163
0164 static ssize_t fop_write(struct file *file, const char __user *buf,
0165                         size_t count, loff_t *ppos)
0166 {
0167     /* See if we got the magic character 'V' and reload the timer */
0168     if (count) {
0169         if (!nowayout) {
0170             size_t ofs;
0171
0172             /* note: just in case someone wrote the
0173                magic character five months ago... */
0174             wdt_expect_close = 0;
0175
0176             /* scan to see whether or not we got the
0177                magic character */
0178             for (ofs = 0; ofs != count; ofs++) {
0179                 char c;
0180                 if (get_user(c, buf + ofs))
0181                     return -EFAULT;
0182                 if (c == 'V')
0183                     wdt_expect_close = 42;
0184             }
0185         }
0186
0187         /* Well, anyhow someone wrote to us, we should
0188            return that favour */
0189         wdt_keepalive();
0190     }
0191     return count;
0192 }
0193
0194 static int fop_open(struct inode *inode, struct file *file)
0195 {
0196     /* Just in case we're already talking to someone... */
0197     if (test_and_set_bit(0, &wdt_is_open))
0198         return -EBUSY;
0199
0200     if (nowayout)
0201         __module_get(THIS_MODULE);
0202
0203     /* Good, fire up the show */
0204     wdt_startup();
0205     return stream_open(inode, file);
0206 }
0207
0208 static int fop_close(struct inode *inode, struct file *file)
0209 {
0210     if (wdt_expect_close == 42)
0211         wdt_turnoff();
0212     else {
0213         del_timer(&timer);
0214         pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
0215     }
0216     clear_bit(0, &wdt_is_open);
0217     wdt_expect_close = 0;
0218     return 0;
0219 }
0220
0221 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
0222 {
0223     void __user *argp = (void __user *)arg;
0224     int __user *p = argp;
0225     static const struct watchdog_info ident = {
0226         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
0227                             WDIOF_MAGICCLOSE,
0228         .firmware_version = 1,
0229         .identity = "SBC60xx",
0230     };
0231
0232     switch (cmd) {
0233     case WDIOC_GETSUPPORT:
0234         return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
0235     case WDIOC_GETSTATUS:
0236     case WDIOC_GETBOOTSTATUS:
0237         return put_user(0, p);
0238     case WDIOC_SETOPTIONS:
0239     {
0240         int new_options, retval = -EINVAL;
0241         if (get_user(new_options, p))
0242             return -EFAULT;
0243         if (new_options & WDIOS_DISABLECARD) {
0244             wdt_turnoff();
0245             retval = 0;
0246         }
0247         if (new_options & WDIOS_ENABLECARD) {
0248             wdt_startup();
0249             retval = 0;
0250         }
0251         return retval;
0252     }
0253     case WDIOC_KEEPALIVE:
0254         wdt_keepalive();
0255         return 0;
0256     case WDIOC_SETTIMEOUT:
0257     {
0258         int new_timeout;
0259         if (get_user(new_timeout, p))
0260             return -EFAULT;
0261         /* arbitrary upper limit */
0262         if (new_timeout < 1 || new_timeout > 3600)
0263             return -EINVAL;
0264
0265         timeout = new_timeout;
0266         wdt_keepalive();
0267     }
0268         fallthrough;
0269     case WDIOC_GETTIMEOUT:
0270         return put_user(timeout, p);
0271     default:
0272         return -ENOTTY;
0273     }
0274 }
0275
0276 static const struct file_operations wdt_fops = {
0277     .owner      = THIS_MODULE,
0278     .llseek     = no_llseek,
0279     .write      = fop_write,
0280     .open       = fop_open,
0281     .release    = fop_close,
0282     .unlocked_ioctl = fop_ioctl,
0283     .compat_ioctl   = compat_ptr_ioctl,
0284 };
0285
0286 static struct miscdevice wdt_miscdev = {
0287     .minor = WATCHDOG_MINOR,
0288     .name = "watchdog",
0289     .fops = &wdt_fops,
0290 };
0291
0292 /*
0293  *  Notifier for system down
0294  */
0295
0296 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
0297     void *unused)
0298 {
0299     if (code == SYS_DOWN || code == SYS_HALT)
0300         wdt_turnoff();
0301     return NOTIFY_DONE;
0302 }
0303
0304 /*
0305  *  The WDT needs to learn about soft shutdowns in order to
0306  *  turn the timebomb registers off.
0307  */
0308
0309 static struct notifier_block wdt_notifier = {
0310     .notifier_call = wdt_notify_sys,
0311 };
0312
0313 static void __exit sbc60xxwdt_unload(void)
0314 {
0315     wdt_turnoff();
0316
0317     /* Deregister */
0318     misc_deregister(&wdt_miscdev);
0319
0320     unregister_reboot_notifier(&wdt_notifier);
0321     if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
0322         release_region(wdt_stop, 1);
0323     release_region(wdt_start, 1);
0324 }
0325
0326 static int __init sbc60xxwdt_init(void)
0327 {
0328     int rc = -EBUSY;
0329
0330     if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
0331         timeout = WATCHDOG_TIMEOUT;
0332         pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
0333             timeout);
0334     }
0335
0336     if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
0337         pr_err("I/O address 0x%04x already in use\n", wdt_start);
0338         rc = -EIO;
0339         goto err_out;
0340     }
0341
0342     /* We cannot reserve 0x45 - the kernel already has! */
0343     if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
0344         if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
0345             pr_err("I/O address 0x%04x already in use\n", wdt_stop);
0346             rc = -EIO;
0347             goto err_out_region1;
0348         }
0349     }
0350
0351     rc = register_reboot_notifier(&wdt_notifier);
0352     if (rc) {
0353         pr_err("cannot register reboot notifier (err=%d)\n", rc);
0354         goto err_out_region2;
0355     }
0356
0357     rc = misc_register(&wdt_miscdev);
0358     if (rc) {
0359         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
0360                wdt_miscdev.minor, rc);
0361         goto err_out_reboot;
0362     }
0363     pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
0364         timeout, nowayout);
0365
0366     return 0;
0367
0368 err_out_reboot:
0369     unregister_reboot_notifier(&wdt_notifier);
0370 err_out_region2:
0371     if (wdt_stop != 0x45 && wdt_stop != wdt_start)
0372         release_region(wdt_stop, 1);
0373 err_out_region1:
0374     release_region(wdt_start, 1);
0375 err_out:
0376     return rc;
0377 }
0378
0379 module_init(sbc60xxwdt_init);
0380 module_exit(sbc60xxwdt_unload);
0381
0382 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
0383 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
0384 MODULE_LICENSE("GPL");