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 /* Fall through */ 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 }; 298 299 static struct miscdevice wdt_miscdev = { 300 .minor = WATCHDOG_MINOR, 301 .name = "watchdog", 302 .fops = &wdt_fops, 303 }; 304 305 static int wdt_restart_handle(struct notifier_block *this, unsigned long mode, 306 void *cmd) 307 { 308 /* 309 * Cobalt devices have no way of rebooting themselves other 310 * than getting the watchdog to pull reset, so we restart the 311 * watchdog on reboot with no heartbeat. 312 */ 313 wdt_change(WDT_ENABLE); 314 315 /* loop until the watchdog fires */ 316 while (true) 317 ; 318 319 return NOTIFY_DONE; 320 } 321 322 static struct notifier_block wdt_restart_handler = { 323 .notifier_call = wdt_restart_handle, 324 .priority = 128, 325 }; 326 327 /* 328 * Notifier for system down 329 */ 330 331 static int wdt_notify_sys(struct notifier_block *this, 332 unsigned long code, void *unused) 333 { 334 if (code == SYS_DOWN || code == SYS_HALT) 335 wdt_turnoff(); 336 337 return NOTIFY_DONE; 338 } 339 340 /* 341 * The WDT needs to learn about soft shutdowns in order to 342 * turn the timebomb registers off. 343 */ 344 345 static struct notifier_block wdt_notifier = { 346 .notifier_call = wdt_notify_sys, 347 }; 348 349 static void __exit alim7101_wdt_unload(void) 350 { 351 wdt_turnoff(); 352 /* Deregister */ 353 misc_deregister(&wdt_miscdev); 354 unregister_reboot_notifier(&wdt_notifier); 355 unregister_restart_handler(&wdt_restart_handler); 356 pci_dev_put(alim7101_pmu); 357 } 358 359 static int __init alim7101_wdt_init(void) 360 { 361 int rc = -EBUSY; 362 struct pci_dev *ali1543_south; 363 char tmp; 364 365 pr_info("Steve Hill <steve@navaho.co.uk>\n"); 366 alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101, 367 NULL); 368 if (!alim7101_pmu) { 369 pr_info("ALi M7101 PMU not present - WDT not set\n"); 370 return -EBUSY; 371 } 372 373 /* Set the WDT in the PMU to 1 second */ 374 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02); 375 376 ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533, 377 NULL); 378 if (!ali1543_south) { 379 pr_info("ALi 1543 South-Bridge not present - WDT not set\n"); 380 goto err_out; 381 } 382 pci_read_config_byte(ali1543_south, 0x5e, &tmp); 383 pci_dev_put(ali1543_south); 384 if ((tmp & 0x1e) == 0x00) { 385 if (!use_gpio) { 386 pr_info("Detected old alim7101 revision 'a1d'. If this is a cobalt board, set the 'use_gpio' module parameter.\n"); 387 goto err_out; 388 } 389 nowayout = 1; 390 } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) { 391 pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n"); 392 goto err_out; 393 } 394 395 if (timeout < 1 || timeout > 3600) { 396 /* arbitrary upper limit */ 397 timeout = WATCHDOG_TIMEOUT; 398 pr_info("timeout value must be 1 <= x <= 3600, using %d\n", 399 timeout); 400 } 401 402 rc = register_reboot_notifier(&wdt_notifier); 403 if (rc) { 404 pr_err("cannot register reboot notifier (err=%d)\n", rc); 405 goto err_out; 406 } 407 408 rc = register_restart_handler(&wdt_restart_handler); 409 if (rc) { 410 pr_err("cannot register restart handler (err=%d)\n", rc); 411 goto err_out_reboot; 412 } 413 414 rc = misc_register(&wdt_miscdev); 415 if (rc) { 416 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 417 wdt_miscdev.minor, rc); 418 goto err_out_restart; 419 } 420 421 if (nowayout) 422 __module_get(THIS_MODULE); 423 424 pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n", 425 timeout, nowayout); 426 return 0; 427 428 err_out_restart: 429 unregister_restart_handler(&wdt_restart_handler); 430 err_out_reboot: 431 unregister_reboot_notifier(&wdt_notifier); 432 err_out: 433 pci_dev_put(alim7101_pmu); 434 return rc; 435 } 436 437 module_init(alim7101_wdt_init); 438 module_exit(alim7101_wdt_unload); 439 440 static const struct pci_device_id alim7101_pci_tbl[] __used = { 441 { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) }, 442 { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) }, 443 { } 444 }; 445 446 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl); 447 448 MODULE_AUTHOR("Steve Hill"); 449 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver"); 450 MODULE_LICENSE("GPL"); 451