Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * AMD Elan SC520 processor Watchdog Timer driver |
| 3 | * |
| 4 | * Based on acquirewdt.c by Alan Cox, |
| 5 | * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU General Public License |
| 9 | * as published by the Free Software Foundation; either version |
| 10 | * 2 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * The authors do NOT admit liability nor provide warranty for |
| 13 | * any of this software. This material is provided "AS-IS" in |
| 14 | * the hope that it may be useful for others. |
| 15 | * |
| 16 | * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> |
| 17 | * 9/27 - 2001 [Initial release] |
| 18 | * |
| 19 | * Additional fixes Alan Cox |
| 20 | * - Fixed formatting |
| 21 | * - Removed debug printks |
| 22 | * - Fixed SMP built kernel deadlock |
| 23 | * - Switched to private locks not lock_kernel |
| 24 | * - Used ioremap/writew/readw |
| 25 | * - Added NOWAYOUT support |
| 26 | * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com> |
| 27 | * - Change comments |
| 28 | * - Eliminate fop_llseek |
| 29 | * - Change CONFIG_WATCHDOG_NOWAYOUT semantics |
| 30 | * - Add KERN_* tags to printks |
| 31 | * - fix possible wdt_is_open race |
| 32 | * - Report proper capabilities in watchdog_info |
| 33 | * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT, |
| 34 | * GETTIMEOUT, SETOPTIONS} ioctls |
| 35 | * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be> |
| 36 | * - cleanup of trailing spaces |
| 37 | * - added extra printk's for startup problems |
| 38 | * - use module_param |
| 39 | * - made timeout (the emulated heartbeat) a module_param |
| 40 | * - made the keepalive ping an internal subroutine |
| 41 | * 3/27 - 2004 Changes by Sean Young <sean@mess.org> |
| 42 | * - set MMCR_BASE to 0xfffef000 |
| 43 | * - CBAR does not need to be read |
| 44 | * - removed debugging printks |
| 45 | * |
| 46 | * This WDT driver is different from most other Linux WDT |
| 47 | * drivers in that the driver will ping the watchdog by itself, |
| 48 | * because this particular WDT has a very short timeout (1.6 |
| 49 | * seconds) and it would be insane to count on any userspace |
| 50 | * daemon always getting scheduled within that time frame. |
| 51 | * |
| 52 | * This driver uses memory mapped IO, and spinlock. |
| 53 | */ |
| 54 | |
| 55 | #include <linux/module.h> |
| 56 | #include <linux/moduleparam.h> |
| 57 | #include <linux/types.h> |
| 58 | #include <linux/timer.h> |
| 59 | #include <linux/miscdevice.h> |
| 60 | #include <linux/watchdog.h> |
| 61 | #include <linux/fs.h> |
| 62 | #include <linux/ioport.h> |
| 63 | #include <linux/notifier.h> |
| 64 | #include <linux/reboot.h> |
| 65 | #include <linux/init.h> |
| 66 | |
| 67 | #include <asm/io.h> |
| 68 | #include <asm/uaccess.h> |
| 69 | #include <asm/system.h> |
| 70 | |
| 71 | #define OUR_NAME "sc520_wdt" |
| 72 | #define PFX OUR_NAME ": " |
| 73 | |
| 74 | /* |
| 75 | * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7) |
| 76 | * |
| 77 | * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s |
| 78 | * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s |
| 79 | * |
| 80 | * We will program the SC520 watchdog for a timeout of 2.01s. |
| 81 | * If we reset the watchdog every ~250ms we should be safe. |
| 82 | */ |
| 83 | |
| 84 | #define WDT_INTERVAL (HZ/4+1) |
| 85 | |
| 86 | /* |
| 87 | * We must not require too good response from the userspace daemon. |
| 88 | * Here we require the userspace daemon to send us a heartbeat |
| 89 | * char to /dev/watchdog every 30 seconds. |
| 90 | */ |
| 91 | |
| 92 | #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ |
| 93 | static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ |
| 94 | module_param(timeout, int, 0); |
| 95 | MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); |
| 96 | |
| 97 | #ifdef CONFIG_WATCHDOG_NOWAYOUT |
| 98 | static int nowayout = 1; |
| 99 | #else |
| 100 | static int nowayout = 0; |
| 101 | #endif |
| 102 | |
| 103 | module_param(nowayout, int, 0); |
| 104 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); |
| 105 | |
| 106 | /* |
| 107 | * AMD Elan SC520 - Watchdog Timer Registers |
| 108 | */ |
| 109 | #define MMCR_BASE 0xfffef000 /* The default base address */ |
| 110 | #define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */ |
| 111 | |
| 112 | /* WDT Control Register bit definitions */ |
| 113 | #define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */ |
| 114 | #define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */ |
| 115 | #define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */ |
| 116 | #define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */ |
| 117 | #define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */ |
| 118 | #define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */ |
| 119 | #define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */ |
| 120 | #define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */ |
| 121 | #define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */ |
| 122 | #define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */ |
| 123 | #define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */ |
| 124 | |
| 125 | static __u16 __iomem *wdtmrctl; |
| 126 | |
| 127 | static void wdt_timer_ping(unsigned long); |
| 128 | static struct timer_list timer; |
| 129 | static unsigned long next_heartbeat; |
| 130 | static unsigned long wdt_is_open; |
| 131 | static char wdt_expect_close; |
| 132 | static spinlock_t wdt_spinlock; |
| 133 | |
| 134 | /* |
| 135 | * Whack the dog |
| 136 | */ |
| 137 | |
| 138 | static void wdt_timer_ping(unsigned long data) |
| 139 | { |
| 140 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL |
| 141 | * we agree to ping the WDT |
| 142 | */ |
| 143 | if(time_before(jiffies, next_heartbeat)) |
| 144 | { |
| 145 | /* Ping the WDT */ |
| 146 | spin_lock(&wdt_spinlock); |
| 147 | writew(0xAAAA, wdtmrctl); |
| 148 | writew(0x5555, wdtmrctl); |
| 149 | spin_unlock(&wdt_spinlock); |
| 150 | |
| 151 | /* Re-set the timer interval */ |
| 152 | timer.expires = jiffies + WDT_INTERVAL; |
| 153 | add_timer(&timer); |
| 154 | } else { |
| 155 | printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n"); |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | /* |
| 160 | * Utility routines |
| 161 | */ |
| 162 | |
| 163 | static void wdt_config(int writeval) |
| 164 | { |
| 165 | __u16 dummy; |
| 166 | unsigned long flags; |
| 167 | |
| 168 | /* buy some time (ping) */ |
| 169 | spin_lock_irqsave(&wdt_spinlock, flags); |
| 170 | dummy=readw(wdtmrctl); /* ensure write synchronization */ |
| 171 | writew(0xAAAA, wdtmrctl); |
| 172 | writew(0x5555, wdtmrctl); |
| 173 | /* unlock WDT = make WDT configuration register writable one time */ |
| 174 | writew(0x3333, wdtmrctl); |
| 175 | writew(0xCCCC, wdtmrctl); |
| 176 | /* write WDT configuration register */ |
| 177 | writew(writeval, wdtmrctl); |
| 178 | spin_unlock_irqrestore(&wdt_spinlock, flags); |
| 179 | } |
| 180 | |
| 181 | static int wdt_startup(void) |
| 182 | { |
| 183 | next_heartbeat = jiffies + (timeout * HZ); |
| 184 | |
| 185 | /* Start the timer */ |
| 186 | timer.expires = jiffies + WDT_INTERVAL; |
| 187 | add_timer(&timer); |
| 188 | |
| 189 | /* Start the watchdog */ |
| 190 | wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); |
| 191 | |
| 192 | printk(KERN_INFO PFX "Watchdog timer is now enabled.\n"); |
| 193 | return 0; |
| 194 | } |
| 195 | |
| 196 | static int wdt_turnoff(void) |
| 197 | { |
| 198 | /* Stop the timer */ |
| 199 | del_timer(&timer); |
| 200 | |
| 201 | /* Stop the watchdog */ |
| 202 | wdt_config(0); |
| 203 | |
| 204 | printk(KERN_INFO PFX "Watchdog timer is now disabled...\n"); |
| 205 | return 0; |
| 206 | } |
| 207 | |
| 208 | static int wdt_keepalive(void) |
| 209 | { |
| 210 | /* user land ping */ |
| 211 | next_heartbeat = jiffies + (timeout * HZ); |
| 212 | return 0; |
| 213 | } |
| 214 | |
| 215 | static int wdt_set_heartbeat(int t) |
| 216 | { |
| 217 | if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ |
| 218 | return -EINVAL; |
| 219 | |
| 220 | timeout = t; |
| 221 | return 0; |
| 222 | } |
| 223 | |
| 224 | /* |
| 225 | * /dev/watchdog handling |
| 226 | */ |
| 227 | |
| 228 | static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos) |
| 229 | { |
| 230 | /* See if we got the magic character 'V' and reload the timer */ |
| 231 | if(count) { |
| 232 | if (!nowayout) { |
| 233 | size_t ofs; |
| 234 | |
| 235 | /* note: just in case someone wrote the magic character |
| 236 | * five months ago... */ |
| 237 | wdt_expect_close = 0; |
| 238 | |
| 239 | /* now scan */ |
| 240 | for(ofs = 0; ofs != count; ofs++) { |
| 241 | char c; |
| 242 | if (get_user(c, buf + ofs)) |
| 243 | return -EFAULT; |
| 244 | if(c == 'V') |
| 245 | wdt_expect_close = 42; |
| 246 | } |
| 247 | } |
| 248 | |
| 249 | /* Well, anyhow someone wrote to us, we should return that favour */ |
| 250 | wdt_keepalive(); |
| 251 | } |
| 252 | return count; |
| 253 | } |
| 254 | |
| 255 | static int fop_open(struct inode * inode, struct file * file) |
| 256 | { |
| 257 | nonseekable_open(inode, file); |
| 258 | |
| 259 | /* Just in case we're already talking to someone... */ |
| 260 | if(test_and_set_bit(0, &wdt_is_open)) |
| 261 | return -EBUSY; |
| 262 | if (nowayout) |
| 263 | __module_get(THIS_MODULE); |
| 264 | |
| 265 | /* Good, fire up the show */ |
| 266 | wdt_startup(); |
| 267 | return 0; |
| 268 | } |
| 269 | |
| 270 | static int fop_close(struct inode * inode, struct file * file) |
| 271 | { |
| 272 | if(wdt_expect_close == 42) { |
| 273 | wdt_turnoff(); |
| 274 | } else { |
| 275 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); |
| 276 | wdt_keepalive(); |
| 277 | } |
| 278 | clear_bit(0, &wdt_is_open); |
| 279 | wdt_expect_close = 0; |
| 280 | return 0; |
| 281 | } |
| 282 | |
| 283 | static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, |
| 284 | unsigned long arg) |
| 285 | { |
| 286 | void __user *argp = (void __user *)arg; |
| 287 | int __user *p = argp; |
| 288 | static struct watchdog_info ident = { |
| 289 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, |
| 290 | .firmware_version = 1, |
| 291 | .identity = "SC520", |
| 292 | }; |
| 293 | |
| 294 | switch(cmd) |
| 295 | { |
| 296 | default: |
| 297 | return -ENOIOCTLCMD; |
| 298 | case WDIOC_GETSUPPORT: |
| 299 | return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0; |
| 300 | case WDIOC_GETSTATUS: |
| 301 | case WDIOC_GETBOOTSTATUS: |
| 302 | return put_user(0, p); |
| 303 | case WDIOC_KEEPALIVE: |
| 304 | wdt_keepalive(); |
| 305 | return 0; |
| 306 | case WDIOC_SETOPTIONS: |
| 307 | { |
| 308 | int new_options, retval = -EINVAL; |
| 309 | |
| 310 | if(get_user(new_options, p)) |
| 311 | return -EFAULT; |
| 312 | |
| 313 | if(new_options & WDIOS_DISABLECARD) { |
| 314 | wdt_turnoff(); |
| 315 | retval = 0; |
| 316 | } |
| 317 | |
| 318 | if(new_options & WDIOS_ENABLECARD) { |
| 319 | wdt_startup(); |
| 320 | retval = 0; |
| 321 | } |
| 322 | |
| 323 | return retval; |
| 324 | } |
| 325 | case WDIOC_SETTIMEOUT: |
| 326 | { |
| 327 | int new_timeout; |
| 328 | |
| 329 | if(get_user(new_timeout, p)) |
| 330 | return -EFAULT; |
| 331 | |
| 332 | if(wdt_set_heartbeat(new_timeout)) |
| 333 | return -EINVAL; |
| 334 | |
| 335 | wdt_keepalive(); |
| 336 | /* Fall through */ |
| 337 | } |
| 338 | case WDIOC_GETTIMEOUT: |
| 339 | return put_user(timeout, p); |
| 340 | } |
| 341 | } |
| 342 | |
| 343 | static struct file_operations wdt_fops = { |
| 344 | .owner = THIS_MODULE, |
| 345 | .llseek = no_llseek, |
| 346 | .write = fop_write, |
| 347 | .open = fop_open, |
| 348 | .release = fop_close, |
| 349 | .ioctl = fop_ioctl, |
| 350 | }; |
| 351 | |
| 352 | static struct miscdevice wdt_miscdev = { |
| 353 | .minor = WATCHDOG_MINOR, |
| 354 | .name = "watchdog", |
| 355 | .fops = &wdt_fops, |
| 356 | }; |
| 357 | |
| 358 | /* |
| 359 | * Notifier for system down |
| 360 | */ |
| 361 | |
| 362 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
| 363 | void *unused) |
| 364 | { |
| 365 | if(code==SYS_DOWN || code==SYS_HALT) |
| 366 | wdt_turnoff(); |
| 367 | return NOTIFY_DONE; |
| 368 | } |
| 369 | |
| 370 | /* |
| 371 | * The WDT needs to learn about soft shutdowns in order to |
| 372 | * turn the timebomb registers off. |
| 373 | */ |
| 374 | |
| 375 | static struct notifier_block wdt_notifier = { |
| 376 | .notifier_call = wdt_notify_sys, |
| 377 | }; |
| 378 | |
| 379 | static void __exit sc520_wdt_unload(void) |
| 380 | { |
| 381 | if (!nowayout) |
| 382 | wdt_turnoff(); |
| 383 | |
| 384 | /* Deregister */ |
| 385 | misc_deregister(&wdt_miscdev); |
| 386 | unregister_reboot_notifier(&wdt_notifier); |
| 387 | iounmap(wdtmrctl); |
| 388 | } |
| 389 | |
| 390 | static int __init sc520_wdt_init(void) |
| 391 | { |
| 392 | int rc = -EBUSY; |
| 393 | |
| 394 | spin_lock_init(&wdt_spinlock); |
| 395 | |
| 396 | init_timer(&timer); |
| 397 | timer.function = wdt_timer_ping; |
| 398 | timer.data = 0; |
| 399 | |
| 400 | /* Check that the timeout value is within it's range ; if not reset to the default */ |
| 401 | if (wdt_set_heartbeat(timeout)) { |
| 402 | wdt_set_heartbeat(WATCHDOG_TIMEOUT); |
| 403 | printk(KERN_INFO PFX "timeout value must be 1<=timeout<=3600, using %d\n", |
| 404 | WATCHDOG_TIMEOUT); |
| 405 | } |
| 406 | |
| 407 | wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2); |
| 408 | if (!wdtmrctl) { |
| 409 | printk(KERN_ERR PFX "Unable to remap memory\n"); |
| 410 | rc = -ENOMEM; |
| 411 | goto err_out_region2; |
| 412 | } |
| 413 | |
| 414 | rc = register_reboot_notifier(&wdt_notifier); |
| 415 | if (rc) { |
| 416 | printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", |
| 417 | rc); |
| 418 | goto err_out_ioremap; |
| 419 | } |
| 420 | |
| 421 | rc = misc_register(&wdt_miscdev); |
| 422 | if (rc) { |
| 423 | printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", |
| 424 | WATCHDOG_MINOR, rc); |
| 425 | goto err_out_notifier; |
| 426 | } |
| 427 | |
| 428 | printk(KERN_INFO PFX "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", |
| 429 | timeout,nowayout); |
| 430 | |
| 431 | return 0; |
| 432 | |
| 433 | err_out_notifier: |
| 434 | unregister_reboot_notifier(&wdt_notifier); |
| 435 | err_out_ioremap: |
| 436 | iounmap(wdtmrctl); |
| 437 | err_out_region2: |
| 438 | return rc; |
| 439 | } |
| 440 | |
| 441 | module_init(sc520_wdt_init); |
| 442 | module_exit(sc520_wdt_unload); |
| 443 | |
| 444 | MODULE_AUTHOR("Scott and Bill Jennings"); |
| 445 | MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); |
| 446 | MODULE_LICENSE("GPL"); |
| 447 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |