1 /* 2 * Watchdog for the 7101 PMU version found in the ALi M1535 chipsets 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 */ 9 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 12 #include <linux/module.h> 13 #include <linux/moduleparam.h> 14 #include <linux/types.h> 15 #include <linux/miscdevice.h> 16 #include <linux/watchdog.h> 17 #include <linux/ioport.h> 18 #include <linux/notifier.h> 19 #include <linux/reboot.h> 20 #include <linux/init.h> 21 #include <linux/fs.h> 22 #include <linux/pci.h> 23 #include <linux/uaccess.h> 24 #include <linux/io.h> 25 26 #define WATCHDOG_NAME "ALi_M1535" 27 #define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */ 28 29 /* internal variables */ 30 static unsigned long ali_is_open; 31 static char ali_expect_release; 32 static struct pci_dev *ali_pci; 33 static u32 ali_timeout_bits; /* stores the computed timeout */ 34 static DEFINE_SPINLOCK(ali_lock); /* Guards the hardware */ 35 36 /* module parameters */ 37 static int timeout = WATCHDOG_TIMEOUT; 38 module_param(timeout, int, 0); 39 MODULE_PARM_DESC(timeout, 40 "Watchdog timeout in seconds. (0 < timeout < 18000, default=" 41 __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 42 43 static bool nowayout = WATCHDOG_NOWAYOUT; 44 module_param(nowayout, bool, 0); 45 MODULE_PARM_DESC(nowayout, 46 "Watchdog cannot be stopped once started (default=" 47 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 48 49 /* 50 * ali_start - start watchdog countdown 51 * 52 * Starts the timer running providing the timer has a counter 53 * configuration set. 54 */ 55 56 static void ali_start(void) 57 { 58 u32 val; 59 60 spin_lock(&ali_lock); 61 62 pci_read_config_dword(ali_pci, 0xCC, &val); 63 val &= ~0x3F; /* Mask count */ 64 val |= (1 << 25) | ali_timeout_bits; 65 pci_write_config_dword(ali_pci, 0xCC, val); 66 67 spin_unlock(&ali_lock); 68 } 69 70 /* 71 * ali_stop - stop the timer countdown 72 * 73 * Stop the ALi watchdog countdown 74 */ 75 76 static void ali_stop(void) 77 { 78 u32 val; 79 80 spin_lock(&ali_lock); 81 82 pci_read_config_dword(ali_pci, 0xCC, &val); 83 val &= ~0x3F; /* Mask count to zero (disabled) */ 84 val &= ~(1 << 25); /* and for safety mask the reset enable */ 85 pci_write_config_dword(ali_pci, 0xCC, val); 86 87 spin_unlock(&ali_lock); 88 } 89 90 /* 91 * ali_keepalive - send a keepalive to the watchdog 92 * 93 * Send a keepalive to the timer (actually we restart the timer). 94 */ 95 96 static void ali_keepalive(void) 97 { 98 ali_start(); 99 } 100 101 /* 102 * ali_settimer - compute the timer reload value 103 * @t: time in seconds 104 * 105 * Computes the timeout values needed 106 */ 107 108 static int ali_settimer(int t) 109 { 110 if (t < 0) 111 return -EINVAL; 112 else if (t < 60) 113 ali_timeout_bits = t|(1 << 6); 114 else if (t < 3600) 115 ali_timeout_bits = (t / 60)|(1 << 7); 116 else if (t < 18000) 117 ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7); 118 else 119 return -EINVAL; 120 121 timeout = t; 122 return 0; 123 } 124 125 /* 126 * /dev/watchdog handling 127 */ 128 129 /* 130 * ali_write - writes to ALi watchdog 131 * @file: file from VFS 132 * @data: user address of data 133 * @len: length of data 134 * @ppos: pointer to the file offset 135 * 136 * Handle a write to the ALi watchdog. Writing to the file pings 137 * the watchdog and resets it. Writing the magic 'V' sequence allows 138 * the next close to turn off the watchdog. 139 */ 140 141 static ssize_t ali_write(struct file *file, const char __user *data, 142 size_t len, loff_t *ppos) 143 { 144 /* See if we got the magic character 'V' and reload the timer */ 145 if (len) { 146 if (!nowayout) { 147 size_t i; 148 149 /* note: just in case someone wrote the 150 magic character five months ago... */ 151 ali_expect_release = 0; 152 153 /* scan to see whether or not we got 154 the magic character */ 155 for (i = 0; i != len; i++) { 156 char c; 157 if (get_user(c, data + i)) 158 return -EFAULT; 159 if (c == 'V') 160 ali_expect_release = 42; 161 } 162 } 163 164 /* someone wrote to us, we should reload the timer */ 165 ali_start(); 166 } 167 return len; 168 } 169 170 /* 171 * ali_ioctl - handle watchdog ioctls 172 * @file: VFS file pointer 173 * @cmd: ioctl number 174 * @arg: arguments to the ioctl 175 * 176 * Handle the watchdog ioctls supported by the ALi driver. Really 177 * we want an extension to enable irq ack monitoring and the like 178 */ 179 180 static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 181 { 182 void __user *argp = (void __user *)arg; 183 int __user *p = argp; 184 static const struct watchdog_info ident = { 185 .options = WDIOF_KEEPALIVEPING | 186 WDIOF_SETTIMEOUT | 187 WDIOF_MAGICCLOSE, 188 .firmware_version = 0, 189 .identity = "ALi M1535 WatchDog Timer", 190 }; 191 192 switch (cmd) { 193 case WDIOC_GETSUPPORT: 194 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 195 196 case WDIOC_GETSTATUS: 197 case WDIOC_GETBOOTSTATUS: 198 return put_user(0, p); 199 case WDIOC_SETOPTIONS: 200 { 201 int new_options, retval = -EINVAL; 202 203 if (get_user(new_options, p)) 204 return -EFAULT; 205 if (new_options & WDIOS_DISABLECARD) { 206 ali_stop(); 207 retval = 0; 208 } 209 if (new_options & WDIOS_ENABLECARD) { 210 ali_start(); 211 retval = 0; 212 } 213 return retval; 214 } 215 case WDIOC_KEEPALIVE: 216 ali_keepalive(); 217 return 0; 218 case WDIOC_SETTIMEOUT: 219 { 220 int new_timeout; 221 if (get_user(new_timeout, p)) 222 return -EFAULT; 223 if (ali_settimer(new_timeout)) 224 return -EINVAL; 225 ali_keepalive(); 226 /* Fall */ 227 } 228 case WDIOC_GETTIMEOUT: 229 return put_user(timeout, p); 230 default: 231 return -ENOTTY; 232 } 233 } 234 235 /* 236 * ali_open - handle open of ali watchdog 237 * @inode: inode from VFS 238 * @file: file from VFS 239 * 240 * Open the ALi watchdog device. Ensure only one person opens it 241 * at a time. Also start the watchdog running. 242 */ 243 244 static int ali_open(struct inode *inode, struct file *file) 245 { 246 /* /dev/watchdog can only be opened once */ 247 if (test_and_set_bit(0, &ali_is_open)) 248 return -EBUSY; 249 250 /* Activate */ 251 ali_start(); 252 return nonseekable_open(inode, file); 253 } 254 255 /* 256 * ali_release - close an ALi watchdog 257 * @inode: inode from VFS 258 * @file: file from VFS 259 * 260 * Close the ALi watchdog device. Actual shutdown of the timer 261 * only occurs if the magic sequence has been set. 262 */ 263 264 static int ali_release(struct inode *inode, struct file *file) 265 { 266 /* 267 * Shut off the timer. 268 */ 269 if (ali_expect_release == 42) 270 ali_stop(); 271 else { 272 pr_crit("Unexpected close, not stopping watchdog!\n"); 273 ali_keepalive(); 274 } 275 clear_bit(0, &ali_is_open); 276 ali_expect_release = 0; 277 return 0; 278 } 279 280 /* 281 * ali_notify_sys - System down notifier 282 * 283 * Notifier for system down 284 */ 285 286 287 static int ali_notify_sys(struct notifier_block *this, 288 unsigned long code, void *unused) 289 { 290 if (code == SYS_DOWN || code == SYS_HALT) 291 ali_stop(); /* Turn the WDT off */ 292 return NOTIFY_DONE; 293 } 294 295 /* 296 * Data for PCI driver interface 297 * 298 * This data only exists for exporting the supported 299 * PCI ids via MODULE_DEVICE_TABLE. We do not actually 300 * register a pci_driver, because someone else might one day 301 * want to register another driver on the same PCI id. 302 */ 303 304 static const struct pci_device_id ali_pci_tbl[] __used = { 305 { PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,}, 306 { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,}, 307 { 0, }, 308 }; 309 MODULE_DEVICE_TABLE(pci, ali_pci_tbl); 310 311 /* 312 * ali_find_watchdog - find a 1535 and 7101 313 * 314 * Scans the PCI hardware for a 1535 series bridge and matching 7101 315 * watchdog device. This may be overtight but it is better to be safe 316 */ 317 318 static int __init ali_find_watchdog(void) 319 { 320 struct pci_dev *pdev; 321 u32 wdog; 322 323 /* Check for a 1533/1535 series bridge */ 324 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL); 325 if (pdev == NULL) 326 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL); 327 if (pdev == NULL) 328 return -ENODEV; 329 pci_dev_put(pdev); 330 331 /* Check for the a 7101 PMU */ 332 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL); 333 if (pdev == NULL) 334 return -ENODEV; 335 336 if (pci_enable_device(pdev)) { 337 pci_dev_put(pdev); 338 return -EIO; 339 } 340 341 ali_pci = pdev; 342 343 /* 344 * Initialize the timer bits 345 */ 346 pci_read_config_dword(pdev, 0xCC, &wdog); 347 348 /* Timer bits */ 349 wdog &= ~0x3F; 350 /* Issued events */ 351 wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24)); 352 /* No monitor bits */ 353 wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9)); 354 355 pci_write_config_dword(pdev, 0xCC, wdog); 356 357 return 0; 358 } 359 360 /* 361 * Kernel Interfaces 362 */ 363 364 static const struct file_operations ali_fops = { 365 .owner = THIS_MODULE, 366 .llseek = no_llseek, 367 .write = ali_write, 368 .unlocked_ioctl = ali_ioctl, 369 .open = ali_open, 370 .release = ali_release, 371 }; 372 373 static struct miscdevice ali_miscdev = { 374 .minor = WATCHDOG_MINOR, 375 .name = "watchdog", 376 .fops = &ali_fops, 377 }; 378 379 static struct notifier_block ali_notifier = { 380 .notifier_call = ali_notify_sys, 381 }; 382 383 /* 384 * watchdog_init - module initialiser 385 * 386 * Scan for a suitable watchdog and if so initialize it. Return an error 387 * if we cannot, the error causes the module to unload 388 */ 389 390 static int __init watchdog_init(void) 391 { 392 int ret; 393 394 /* Check whether or not the hardware watchdog is there */ 395 if (ali_find_watchdog() != 0) 396 return -ENODEV; 397 398 /* Check that the timeout value is within it's range; 399 if not reset to the default */ 400 if (timeout < 1 || timeout >= 18000) { 401 timeout = WATCHDOG_TIMEOUT; 402 pr_info("timeout value must be 0 < timeout < 18000, using %d\n", 403 timeout); 404 } 405 406 /* Calculate the watchdog's timeout */ 407 ali_settimer(timeout); 408 409 ret = register_reboot_notifier(&ali_notifier); 410 if (ret != 0) { 411 pr_err("cannot register reboot notifier (err=%d)\n", ret); 412 goto out; 413 } 414 415 ret = misc_register(&ali_miscdev); 416 if (ret != 0) { 417 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 418 WATCHDOG_MINOR, ret); 419 goto unreg_reboot; 420 } 421 422 pr_info("initialized. timeout=%d sec (nowayout=%d)\n", 423 timeout, nowayout); 424 425 out: 426 return ret; 427 unreg_reboot: 428 unregister_reboot_notifier(&ali_notifier); 429 goto out; 430 } 431 432 /* 433 * watchdog_exit - module de-initialiser 434 * 435 * Called while unloading a successfully installed watchdog module. 436 */ 437 438 static void __exit watchdog_exit(void) 439 { 440 /* Stop the timer before we leave */ 441 ali_stop(); 442 443 /* Deregister */ 444 misc_deregister(&ali_miscdev); 445 unregister_reboot_notifier(&ali_notifier); 446 pci_dev_put(ali_pci); 447 } 448 449 module_init(watchdog_init); 450 module_exit(watchdog_exit); 451 452 MODULE_AUTHOR("Alan Cox"); 453 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver"); 454 MODULE_LICENSE("GPL"); 455