1 /* 2 * drivers/char/watchdog/shwdt.c 3 * 4 * Watchdog driver for integrated watchdog in the SuperH processors. 5 * 6 * Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the 10 * Free Software Foundation; either version 2 of the License, or (at your 11 * option) any later version. 12 * 13 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> 14 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT 15 * 16 * 19-Apr-2002 Rob Radez <rob@osinvestor.com> 17 * Added expect close support, made emulated timeout runtime changeable 18 * general cleanups, add some ioctls 19 */ 20 #include <linux/module.h> 21 #include <linux/moduleparam.h> 22 #include <linux/init.h> 23 #include <linux/types.h> 24 #include <linux/miscdevice.h> 25 #include <linux/watchdog.h> 26 #include <linux/reboot.h> 27 #include <linux/notifier.h> 28 #include <linux/ioport.h> 29 #include <linux/fs.h> 30 #include <linux/mm.h> 31 #include <asm/io.h> 32 #include <asm/uaccess.h> 33 #include <asm/watchdog.h> 34 35 #define PFX "shwdt: " 36 37 /* 38 * Default clock division ratio is 5.25 msecs. For an additional table of 39 * values, consult the asm-sh/watchdog.h. Overload this at module load 40 * time. 41 * 42 * In order for this to work reliably we need to have HZ set to 1000 or 43 * something quite higher than 100 (or we need a proper high-res timer 44 * implementation that will deal with this properly), otherwise the 10ms 45 * resolution of a jiffy is enough to trigger the overflow. For things like 46 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though 47 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely 48 * necssary. 49 * 50 * As a result of this timing problem, the only modes that are particularly 51 * feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms 52 * overflow periods respectively. 53 * 54 * Also, since we can't really expect userspace to be responsive enough 55 * before the overflow happens, we maintain two separate timers .. One in 56 * the kernel for clearing out WOVF every 2ms or so (again, this depends on 57 * HZ == 1000), and another for monitoring userspace writes to the WDT device. 58 * 59 * As such, we currently use a configurable heartbeat interval which defaults 60 * to 30s. In this case, the userspace daemon is only responsible for periodic 61 * writes to the device before the next heartbeat is scheduled. If the daemon 62 * misses its deadline, the kernel timer will allow the WDT to overflow. 63 */ 64 static int clock_division_ratio = WTCSR_CKS_4096; 65 66 #define next_ping_period(cks) msecs_to_jiffies(cks - 4) 67 68 static void sh_wdt_ping(unsigned long data); 69 70 static unsigned long shwdt_is_open; 71 static struct watchdog_info sh_wdt_info; 72 static char shwdt_expect_close; 73 static DEFINE_TIMER(timer, sh_wdt_ping, 0, 0); 74 static unsigned long next_heartbeat; 75 76 #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ 77 static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ 78 79 static int nowayout = WATCHDOG_NOWAYOUT; 80 81 /** 82 * sh_wdt_start - Start the Watchdog 83 * 84 * Starts the watchdog. 85 */ 86 static void sh_wdt_start(void) 87 { 88 __u8 csr; 89 90 next_heartbeat = jiffies + (heartbeat * HZ); 91 mod_timer(&timer, next_ping_period(clock_division_ratio)); 92 93 csr = sh_wdt_read_csr(); 94 csr |= WTCSR_WT | clock_division_ratio; 95 sh_wdt_write_csr(csr); 96 97 sh_wdt_write_cnt(0); 98 99 /* 100 * These processors have a bit of an inconsistent initialization 101 * process.. starting with SH-3, RSTS was moved to WTCSR, and the 102 * RSTCSR register was removed. 103 * 104 * On the SH-2 however, in addition with bits being in different 105 * locations, we must deal with RSTCSR outright.. 106 */ 107 csr = sh_wdt_read_csr(); 108 csr |= WTCSR_TME; 109 csr &= ~WTCSR_RSTS; 110 sh_wdt_write_csr(csr); 111 112 #ifdef CONFIG_CPU_SH2 113 /* 114 * Whoever came up with the RSTCSR semantics must've been smoking 115 * some of the good stuff, since in addition to the WTCSR/WTCNT write 116 * brain-damage, it's managed to fuck things up one step further.. 117 * 118 * If we need to clear the WOVF bit, the upper byte has to be 0xa5.. 119 * but if we want to touch RSTE or RSTS, the upper byte has to be 120 * 0x5a.. 121 */ 122 csr = sh_wdt_read_rstcsr(); 123 csr &= ~RSTCSR_RSTS; 124 sh_wdt_write_rstcsr(csr); 125 #endif 126 } 127 128 /** 129 * sh_wdt_stop - Stop the Watchdog 130 * Stops the watchdog. 131 */ 132 static void sh_wdt_stop(void) 133 { 134 __u8 csr; 135 136 del_timer(&timer); 137 138 csr = sh_wdt_read_csr(); 139 csr &= ~WTCSR_TME; 140 sh_wdt_write_csr(csr); 141 } 142 143 /** 144 * sh_wdt_keepalive - Keep the Userspace Watchdog Alive 145 * The Userspace watchdog got a KeepAlive: schedule the next heartbeat. 146 */ 147 static inline void sh_wdt_keepalive(void) 148 { 149 next_heartbeat = jiffies + (heartbeat * HZ); 150 } 151 152 /** 153 * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat 154 * Set the Userspace Watchdog heartbeat 155 */ 156 static int sh_wdt_set_heartbeat(int t) 157 { 158 if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */ 159 return -EINVAL; 160 161 heartbeat = t; 162 return 0; 163 } 164 165 /** 166 * sh_wdt_ping - Ping the Watchdog 167 * @data: Unused 168 * 169 * Clears overflow bit, resets timer counter. 170 */ 171 static void sh_wdt_ping(unsigned long data) 172 { 173 if (time_before(jiffies, next_heartbeat)) { 174 __u8 csr; 175 176 csr = sh_wdt_read_csr(); 177 csr &= ~WTCSR_IOVF; 178 sh_wdt_write_csr(csr); 179 180 sh_wdt_write_cnt(0); 181 182 mod_timer(&timer, next_ping_period(clock_division_ratio)); 183 } else 184 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping " 185 "the watchdog\n"); 186 } 187 188 /** 189 * sh_wdt_open - Open the Device 190 * @inode: inode of device 191 * @file: file handle of device 192 * 193 * Watchdog device is opened and started. 194 */ 195 static int sh_wdt_open(struct inode *inode, struct file *file) 196 { 197 if (test_and_set_bit(0, &shwdt_is_open)) 198 return -EBUSY; 199 if (nowayout) 200 __module_get(THIS_MODULE); 201 202 sh_wdt_start(); 203 204 return nonseekable_open(inode, file); 205 } 206 207 /** 208 * sh_wdt_close - Close the Device 209 * @inode: inode of device 210 * @file: file handle of device 211 * 212 * Watchdog device is closed and stopped. 213 */ 214 static int sh_wdt_close(struct inode *inode, struct file *file) 215 { 216 if (shwdt_expect_close == 42) { 217 sh_wdt_stop(); 218 } else { 219 printk(KERN_CRIT PFX "Unexpected close, not " 220 "stopping watchdog!\n"); 221 sh_wdt_keepalive(); 222 } 223 224 clear_bit(0, &shwdt_is_open); 225 shwdt_expect_close = 0; 226 227 return 0; 228 } 229 230 /** 231 * sh_wdt_write - Write to Device 232 * @file: file handle of device 233 * @buf: buffer to write 234 * @count: length of buffer 235 * @ppos: offset 236 * 237 * Pings the watchdog on write. 238 */ 239 static ssize_t sh_wdt_write(struct file *file, const char *buf, 240 size_t count, loff_t *ppos) 241 { 242 if (count) { 243 if (!nowayout) { 244 size_t i; 245 246 shwdt_expect_close = 0; 247 248 for (i = 0; i != count; i++) { 249 char c; 250 if (get_user(c, buf + i)) 251 return -EFAULT; 252 if (c == 'V') 253 shwdt_expect_close = 42; 254 } 255 } 256 sh_wdt_keepalive(); 257 } 258 259 return count; 260 } 261 262 /** 263 * sh_wdt_mmap - map WDT/CPG registers into userspace 264 * @file: file structure for the device 265 * @vma: VMA to map the registers into 266 * 267 * A simple mmap() implementation for the corner cases where the counter 268 * needs to be mapped in userspace directly. Due to the relatively small 269 * size of the area, neighbouring registers not necessarily tied to the 270 * CPG will also be accessible through the register page, so this remains 271 * configurable for users that really know what they're doing. 272 * 273 * Additionaly, the register page maps in the CPG register base relative 274 * to the nearest page-aligned boundary, which requires that userspace do 275 * the appropriate CPU subtype math for calculating the page offset for 276 * the counter value. 277 */ 278 static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma) 279 { 280 int ret = -ENOSYS; 281 282 #ifdef CONFIG_SH_WDT_MMAP 283 unsigned long addr; 284 285 /* Only support the simple cases where we map in a register page. */ 286 if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff) 287 return -EINVAL; 288 289 /* 290 * Pick WTCNT as the start, it's usually the first register after the 291 * FRQCR, and neither one are generally page-aligned out of the box. 292 */ 293 addr = WTCNT & ~(PAGE_SIZE - 1); 294 295 vma->vm_flags |= VM_IO; 296 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 297 298 if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT, 299 PAGE_SIZE, vma->vm_page_prot)) { 300 printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n", 301 __FUNCTION__); 302 return -EAGAIN; 303 } 304 305 ret = 0; 306 #endif 307 308 return ret; 309 } 310 311 /** 312 * sh_wdt_ioctl - Query Device 313 * @inode: inode of device 314 * @file: file handle of device 315 * @cmd: watchdog command 316 * @arg: argument 317 * 318 * Query basic information from the device or ping it, as outlined by the 319 * watchdog API. 320 */ 321 static int sh_wdt_ioctl(struct inode *inode, struct file *file, 322 unsigned int cmd, unsigned long arg) 323 { 324 int new_heartbeat; 325 int options, retval = -EINVAL; 326 327 switch (cmd) { 328 case WDIOC_GETSUPPORT: 329 return copy_to_user((struct watchdog_info *)arg, 330 &sh_wdt_info, 331 sizeof(sh_wdt_info)) ? -EFAULT : 0; 332 case WDIOC_GETSTATUS: 333 case WDIOC_GETBOOTSTATUS: 334 return put_user(0, (int *)arg); 335 case WDIOC_KEEPALIVE: 336 sh_wdt_keepalive(); 337 return 0; 338 case WDIOC_SETTIMEOUT: 339 if (get_user(new_heartbeat, (int *)arg)) 340 return -EFAULT; 341 342 if (sh_wdt_set_heartbeat(new_heartbeat)) 343 return -EINVAL; 344 345 sh_wdt_keepalive(); 346 /* Fall */ 347 case WDIOC_GETTIMEOUT: 348 return put_user(heartbeat, (int *)arg); 349 case WDIOC_SETOPTIONS: 350 if (get_user(options, (int *)arg)) 351 return -EFAULT; 352 353 if (options & WDIOS_DISABLECARD) { 354 sh_wdt_stop(); 355 retval = 0; 356 } 357 358 if (options & WDIOS_ENABLECARD) { 359 sh_wdt_start(); 360 retval = 0; 361 } 362 363 return retval; 364 default: 365 return -ENOTTY; 366 } 367 368 return 0; 369 } 370 371 /** 372 * sh_wdt_notify_sys - Notifier Handler 373 * @this: notifier block 374 * @code: notifier event 375 * @unused: unused 376 * 377 * Handles specific events, such as turning off the watchdog during a 378 * shutdown event. 379 */ 380 static int sh_wdt_notify_sys(struct notifier_block *this, 381 unsigned long code, void *unused) 382 { 383 if (code == SYS_DOWN || code == SYS_HALT) 384 sh_wdt_stop(); 385 386 return NOTIFY_DONE; 387 } 388 389 static const struct file_operations sh_wdt_fops = { 390 .owner = THIS_MODULE, 391 .llseek = no_llseek, 392 .write = sh_wdt_write, 393 .ioctl = sh_wdt_ioctl, 394 .open = sh_wdt_open, 395 .release = sh_wdt_close, 396 .mmap = sh_wdt_mmap, 397 }; 398 399 static struct watchdog_info sh_wdt_info = { 400 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | 401 WDIOF_MAGICCLOSE, 402 .firmware_version = 1, 403 .identity = "SH WDT", 404 }; 405 406 static struct notifier_block sh_wdt_notifier = { 407 .notifier_call = sh_wdt_notify_sys, 408 }; 409 410 static struct miscdevice sh_wdt_miscdev = { 411 .minor = WATCHDOG_MINOR, 412 .name = "watchdog", 413 .fops = &sh_wdt_fops, 414 }; 415 416 /** 417 * sh_wdt_init - Initialize module 418 * Registers the device and notifier handler. Actual device 419 * initialization is handled by sh_wdt_open(). 420 */ 421 static int __init sh_wdt_init(void) 422 { 423 int rc; 424 425 if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) { 426 clock_division_ratio = WTCSR_CKS_4096; 427 printk(KERN_INFO PFX "clock_division_ratio value must " 428 "be 0x5<=x<=0x7, using %d\n", clock_division_ratio); 429 } 430 431 rc = sh_wdt_set_heartbeat(heartbeat); 432 if (unlikely(rc)) { 433 heartbeat = WATCHDOG_HEARTBEAT; 434 printk(KERN_INFO PFX "heartbeat value must " 435 "be 1<=x<=3600, using %d\n", heartbeat); 436 } 437 438 rc = register_reboot_notifier(&sh_wdt_notifier); 439 if (unlikely(rc)) { 440 printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n", 441 rc); 442 return rc; 443 } 444 445 rc = misc_register(&sh_wdt_miscdev); 446 if (unlikely(rc)) { 447 printk(KERN_ERR PFX "Can't register miscdev on " 448 "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc); 449 unregister_reboot_notifier(&sh_wdt_notifier); 450 return rc; 451 } 452 453 printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n", 454 heartbeat, nowayout); 455 456 return 0; 457 } 458 459 /** 460 * sh_wdt_exit - Deinitialize module 461 * Unregisters the device and notifier handler. Actual device 462 * deinitialization is handled by sh_wdt_close(). 463 */ 464 static void __exit sh_wdt_exit(void) 465 { 466 misc_deregister(&sh_wdt_miscdev); 467 unregister_reboot_notifier(&sh_wdt_notifier); 468 } 469 470 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); 471 MODULE_DESCRIPTION("SuperH watchdog driver"); 472 MODULE_LICENSE("GPL"); 473 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 474 475 module_param(clock_division_ratio, int, 0); 476 MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) to 0x7 (5.25ms). (default=" __MODULE_STRING(clock_division_ratio) ")"); 477 478 module_param(heartbeat, int, 0); 479 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); 480 481 module_param(nowayout, int, 0); 482 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 483 484 module_init(sh_wdt_init); 485 module_exit(sh_wdt_exit); 486