drivers/watchdog/alim7101_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      ALi M7101 PMU Computer Watchdog Timer driver
   4  *
   5  *      Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
   6  *      and the Cobalt kernel WDT timer driver by Tim Hockin
   7  *                                            <thockin@cobaltnet.com>
   8  *
   9  *      (c)2002 Steve Hill <steve@navaho.co.uk>
  10  *
  11  *  This WDT driver is different from most other Linux WDT
  12  *  drivers in that the driver will ping the watchdog by itself,
  13  *  because this particular WDT has a very short timeout (1.6
  14  *  seconds) and it would be insane to count on any userspace
  15  *  daemon always getting scheduled within that time frame.
  16  *
  17  *  Additions:
  18  *   Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
  19  *                  found on very old cobalt hardware.
  20  *                  -- Mike Waychison <michael.waychison@sun.com>
  21  */
  22
  23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/types.h>
  28 #include <linux/timer.h>
  29 #include <linux/miscdevice.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/ioport.h>
  32 #include <linux/notifier.h>
  33 #include <linux/reboot.h>
  34 #include <linux/init.h>
  35 #include <linux/fs.h>
  36 #include <linux/pci.h>
  37 #include <linux/io.h>
  38 #include <linux/uaccess.h>
  39
  40
  41 #define WDT_ENABLE 0x9C
  42 #define WDT_DISABLE 0x8C
  43
  44 #define ALI_7101_WDT    0x92
  45 #define ALI_7101_GPIO   0x7D
  46 #define ALI_7101_GPIO_O 0x7E
  47 #define ALI_WDT_ARM     0x01
  48
  49 /*
  50  * We're going to use a 1 second timeout.
  51  * If we reset the watchdog every ~250ms we should be safe.  */
  52
  53 #define WDT_INTERVAL (HZ/4+1)
  54
  55 /*
  56  * We must not require too good response from the userspace daemon.
  57  * Here we require the userspace daemon to send us a heartbeat
  58  * char to /dev/watchdog every 30 seconds.
  59  */
  60
  61 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  62 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  63 static int timeout = WATCHDOG_TIMEOUT;
  64 module_param(timeout, int, 0);
  65 MODULE_PARM_DESC(timeout,
  66                 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  67                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  68
  69 static int use_gpio; /* Use the pic (for a1d revision alim7101) */
  70 module_param(use_gpio, int, 0);
  71 MODULE_PARM_DESC(use_gpio,
  72                 "Use the gpio watchdog (required by old cobalt boards).");
  73
  74 static void wdt_timer_ping(struct timer_list *);
  75 static DEFINE_TIMER(timer, wdt_timer_ping);
  76 static unsigned long next_heartbeat;
  77 static unsigned long wdt_is_open;
  78 static char wdt_expect_close;
  79 static struct pci_dev *alim7101_pmu;
  80
  81 static bool nowayout = WATCHDOG_NOWAYOUT;
  82 module_param(nowayout, bool, 0);
  83 MODULE_PARM_DESC(nowayout,
  84                 "Watchdog cannot be stopped once started (default="
  85                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  86
  87 /*
  88  *      Whack the dog
  89  */
  90
  91 static void wdt_timer_ping(struct timer_list *unused)
  92 {
  93         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
  94          * we agree to ping the WDT
  95          */
  96         char tmp;
  97
  98         if (time_before(jiffies, next_heartbeat)) {
  99                 /* Ping the WDT (this is actually a disarm/arm sequence) */
 100                 pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
 101                 pci_write_config_byte(alim7101_pmu,
 102                                         ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
 103                 pci_write_config_byte(alim7101_pmu,
 104                                         ALI_7101_WDT, (tmp | ALI_WDT_ARM));
 105                 if (use_gpio) {
 106                         pci_read_config_byte(alim7101_pmu,
 107                                         ALI_7101_GPIO_O, &tmp);
 108                         pci_write_config_byte(alim7101_pmu,
 109                                         ALI_7101_GPIO_O, tmp | 0x20);
 110                         pci_write_config_byte(alim7101_pmu,
 111                                         ALI_7101_GPIO_O, tmp & ~0x20);
 112                 }
 113         } else {
 114                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 115         }
 116         /* Re-set the timer interval */
 117         mod_timer(&timer, jiffies + WDT_INTERVAL);
 118 }
 119
 120 /*
 121  * Utility routines
 122  */
 123
 124 static void wdt_change(int writeval)
 125 {
 126         char tmp;
 127
 128         pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
 129         if (writeval == WDT_ENABLE) {
 130                 pci_write_config_byte(alim7101_pmu,
 131                                         ALI_7101_WDT, (tmp | ALI_WDT_ARM));
 132                 if (use_gpio) {
 133                         pci_read_config_byte(alim7101_pmu,
 134                                         ALI_7101_GPIO_O, &tmp);
 135                         pci_write_config_byte(alim7101_pmu,
 136                                         ALI_7101_GPIO_O, tmp & ~0x20);
 137                 }
 138
 139         } else {
 140                 pci_write_config_byte(alim7101_pmu,
 141                                         ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
 142                 if (use_gpio) {
 143                         pci_read_config_byte(alim7101_pmu,
 144                                         ALI_7101_GPIO_O, &tmp);
 145                         pci_write_config_byte(alim7101_pmu,
 146                                         ALI_7101_GPIO_O, tmp | 0x20);
 147                 }
 148         }
 149 }
 150
 151 static void wdt_startup(void)
 152 {
 153         next_heartbeat = jiffies + (timeout * HZ);
 154
 155         /* We must enable before we kick off the timer in case the timer
 156            occurs as we ping it */
 157
 158         wdt_change(WDT_ENABLE);
 159
 160         /* Start the timer */
 161         mod_timer(&timer, jiffies + WDT_INTERVAL);
 162
 163         pr_info("Watchdog timer is now enabled\n");
 164 }
 165
 166 static void wdt_turnoff(void)
 167 {
 168         /* Stop the timer */
 169         del_timer_sync(&timer);
 170         wdt_change(WDT_DISABLE);
 171         pr_info("Watchdog timer is now disabled...\n");
 172 }
 173
 174 static void wdt_keepalive(void)
 175 {
 176         /* user land ping */
 177         next_heartbeat = jiffies + (timeout * HZ);
 178 }
 179
 180 /*
 181  * /dev/watchdog handling
 182  */
 183
 184 static ssize_t fop_write(struct file *file, const char __user *buf,
 185                                                 size_t count, loff_t *ppos)
 186 {
 187         /* See if we got the magic character 'V' and reload the timer */
 188         if (count) {
 189                 if (!nowayout) {
 190                         size_t ofs;
 191
 192                         /* note: just in case someone wrote the magic character
 193                          * five months ago... */
 194                         wdt_expect_close = 0;
 195
 196                         /* now scan */
 197                         for (ofs = 0; ofs != count; ofs++) {
 198                                 char c;
 199                                 if (get_user(c, buf + ofs))
 200                                         return -EFAULT;
 201                                 if (c == 'V')
 202                                         wdt_expect_close = 42;
 203                         }
 204                 }
 205                 /* someone wrote to us, we should restart timer */
 206                 wdt_keepalive();
 207         }
 208         return count;
 209 }
 210
 211 static int fop_open(struct inode *inode, struct file *file)
 212 {
 213         /* Just in case we're already talking to someone... */
 214         if (test_and_set_bit(0, &wdt_is_open))
 215                 return -EBUSY;
 216         /* Good, fire up the show */
 217         wdt_startup();
 218         return stream_open(inode, file);
 219 }
 220
 221 static int fop_close(struct inode *inode, struct file *file)
 222 {
 223         if (wdt_expect_close == 42)
 224                 wdt_turnoff();
 225         else {
 226                 /* wim: shouldn't there be a: del_timer(&timer); */
 227                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 228         }
 229         clear_bit(0, &wdt_is_open);
 230         wdt_expect_close = 0;
 231         return 0;
 232 }
 233
 234 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 235 {
 236         void __user *argp = (void __user *)arg;
 237         int __user *p = argp;
 238         static const struct watchdog_info ident = {
 239                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 240                                                         | WDIOF_MAGICCLOSE,
 241                 .firmware_version = 1,
 242                 .identity = "ALiM7101",
 243         };
 244
 245         switch (cmd) {
 246         case WDIOC_GETSUPPORT:
 247                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 248         case WDIOC_GETSTATUS:
 249         case WDIOC_GETBOOTSTATUS:
 250                 return put_user(0, p);
 251         case WDIOC_SETOPTIONS:
 252         {
 253                 int new_options, retval = -EINVAL;
 254
 255                 if (get_user(new_options, p))
 256                         return -EFAULT;
 257                 if (new_options & WDIOS_DISABLECARD) {
 258                         wdt_turnoff();
 259                         retval = 0;
 260                 }
 261                 if (new_options & WDIOS_ENABLECARD) {
 262                         wdt_startup();
 263                         retval = 0;
 264                 }
 265                 return retval;
 266         }
 267         case WDIOC_KEEPALIVE:
 268                 wdt_keepalive();
 269                 return 0;
 270         case WDIOC_SETTIMEOUT:
 271         {
 272                 int new_timeout;
 273
 274                 if (get_user(new_timeout, p))
 275                         return -EFAULT;
 276                 /* arbitrary upper limit */
 277                 if (new_timeout < 1 || new_timeout > 3600)
 278                         return -EINVAL;
 279                 timeout = new_timeout;
 280                 wdt_keepalive();
 281         }
 282                 fallthrough;
 283         case WDIOC_GETTIMEOUT:
 284                 return put_user(timeout, p);
 285         default:
 286                 return -ENOTTY;
 287         }
 288 }
 289
 290 static const struct file_operations wdt_fops = {
 291         .owner          =       THIS_MODULE,
 292         .llseek         =       no_llseek,
 293         .write          =       fop_write,
 294         .open           =       fop_open,
 295         .release        =       fop_close,
 296         .unlocked_ioctl =       fop_ioctl,
 297         .compat_ioctl   =       compat_ptr_ioctl,
 298 };
 299
 300 static struct miscdevice wdt_miscdev = {
 301         .minor  =       WATCHDOG_MINOR,
 302         .name   =       "watchdog",
 303         .fops   =       &wdt_fops,
 304 };
 305
 306 static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
 307                               void *cmd)
 308 {
 309         /*
 310          * Cobalt devices have no way of rebooting themselves other
 311          * than getting the watchdog to pull reset, so we restart the
 312          * watchdog on reboot with no heartbeat.
 313          */
 314         wdt_change(WDT_ENABLE);
 315
 316         /* loop until the watchdog fires */
 317         while (true)
 318                 ;
 319
 320         return NOTIFY_DONE;
 321 }
 322
 323 static struct notifier_block wdt_restart_handler = {
 324         .notifier_call = wdt_restart_handle,
 325         .priority = 128,
 326 };
 327
 328 /*
 329  *      Notifier for system down
 330  */
 331
 332 static int wdt_notify_sys(struct notifier_block *this,
 333                                         unsigned long code, void *unused)
 334 {
 335         if (code == SYS_DOWN || code == SYS_HALT)
 336                 wdt_turnoff();
 337
 338         return NOTIFY_DONE;
 339 }
 340
 341 /*
 342  *      The WDT needs to learn about soft shutdowns in order to
 343  *      turn the timebomb registers off.
 344  */
 345
 346 static struct notifier_block wdt_notifier = {
 347         .notifier_call = wdt_notify_sys,
 348 };
 349
 350 static void __exit alim7101_wdt_unload(void)
 351 {
 352         wdt_turnoff();
 353         /* Deregister */
 354         misc_deregister(&wdt_miscdev);
 355         unregister_reboot_notifier(&wdt_notifier);
 356         unregister_restart_handler(&wdt_restart_handler);
 357         pci_dev_put(alim7101_pmu);
 358 }
 359
 360 static int __init alim7101_wdt_init(void)
 361 {
 362         int rc = -EBUSY;
 363         struct pci_dev *ali1543_south;
 364         char tmp;
 365
 366         pr_info("Steve Hill <steve@navaho.co.uk>\n");
 367         alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
 368                 NULL);
 369         if (!alim7101_pmu) {
 370                 pr_info("ALi M7101 PMU not present - WDT not set\n");
 371                 return -EBUSY;
 372         }
 373
 374         /* Set the WDT in the PMU to 1 second */
 375         pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
 376
 377         ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
 378                 NULL);
 379         if (!ali1543_south) {
 380                 pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
 381                 goto err_out;
 382         }
 383         pci_read_config_byte(ali1543_south, 0x5e, &tmp);
 384         pci_dev_put(ali1543_south);
 385         if ((tmp & 0x1e) == 0x00) {
 386                 if (!use_gpio) {
 387                         pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
 388                         goto err_out;
 389                 }
 390                 nowayout = 1;
 391         } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
 392                 pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
 393                 goto err_out;
 394         }
 395
 396         if (timeout < 1 || timeout > 3600) {
 397                 /* arbitrary upper limit */
 398                 timeout = WATCHDOG_TIMEOUT;
 399                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 400                         timeout);
 401         }
 402
 403         rc = register_reboot_notifier(&wdt_notifier);
 404         if (rc) {
 405                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 406                 goto err_out;
 407         }
 408
 409         rc = register_restart_handler(&wdt_restart_handler);
 410         if (rc) {
 411                 pr_err("cannot register restart handler (err=%d)\n", rc);
 412                 goto err_out_reboot;
 413         }
 414
 415         rc = misc_register(&wdt_miscdev);
 416         if (rc) {
 417                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 418                        wdt_miscdev.minor, rc);
 419                 goto err_out_restart;
 420         }
 421
 422         if (nowayout)
 423                 __module_get(THIS_MODULE);
 424
 425         pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
 426                 timeout, nowayout);
 427         return 0;
 428
 429 err_out_restart:
 430         unregister_restart_handler(&wdt_restart_handler);
 431 err_out_reboot:
 432         unregister_reboot_notifier(&wdt_notifier);
 433 err_out:
 434         pci_dev_put(alim7101_pmu);
 435         return rc;
 436 }
 437
 438 module_init(alim7101_wdt_init);
 439 module_exit(alim7101_wdt_unload);
 440
 441 static const struct pci_device_id alim7101_pci_tbl[] __used = {
 442         { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
 443         { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
 444         { }
 445 };
 446
 447 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
 448
 449 MODULE_AUTHOR("Steve Hill");
 450 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
 451 MODULE_LICENSE("GPL");