1 /*
2 * drivers/watchdog/shwdt.c
3 *
4 * Watchdog driver for integrated watchdog in the SuperH processors.
5 *
6 * Copyright (C) 2001 - 2010 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
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23 #include <linux/module.h>
24 #include <linux/moduleparam.h>
25 #include <linux/platform_device.h>
26 #include <linux/init.h>
27 #include <linux/types.h>
28 #include <linux/miscdevice.h>
29 #include <linux/watchdog.h>
30 #include <linux/reboot.h>
31 #include <linux/notifier.h>
32 #include <linux/ioport.h>
33 #include <linux/fs.h>
34 #include <linux/mm.h>
35 #include <linux/slab.h>
36 #include <linux/io.h>
37 #include <linux/uaccess.h>
38 #include <asm/watchdog.h>
39
40 #define DRV_NAME "sh-wdt"
41
42 /*
43 * Default clock division ratio is 5.25 msecs. For an additional table of
44 * values, consult the asm-sh/watchdog.h. Overload this at module load
45 * time.
46 *
47 * In order for this to work reliably we need to have HZ set to 1000 or
48 * something quite higher than 100 (or we need a proper high-res timer
49 * implementation that will deal with this properly), otherwise the 10ms
50 * resolution of a jiffy is enough to trigger the overflow. For things like
51 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
52 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
53 * necssary.
54 *
55 * As a result of this timing problem, the only modes that are particularly
56 * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
57 * overflow periods respectively.
58 *
59 * Also, since we can't really expect userspace to be responsive enough
60 * before the overflow happens, we maintain two separate timers .. One in
61 * the kernel for clearing out WOVF every 2ms or so (again, this depends on
62 * HZ == 1000), and another for monitoring userspace writes to the WDT device.
63 *
64 * As such, we currently use a configurable heartbeat interval which defaults
65 * to 30s. In this case, the userspace daemon is only responsible for periodic
66 * writes to the device before the next heartbeat is scheduled. If the daemon
67 * misses its deadline, the kernel timer will allow the WDT to overflow.
68 */
69 static int clock_division_ratio = WTCSR_CKS_4096;
70 #define next_ping_period(cks) (jiffies + msecs_to_jiffies(cks - 4))
71
72 static const struct watchdog_info sh_wdt_info;
73 static struct platform_device *sh_wdt_dev;
74 static DEFINE_SPINLOCK(shwdt_lock);
75
76 #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
77 static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
78 static bool nowayout = WATCHDOG_NOWAYOUT;
79 static unsigned long next_heartbeat;
80
81 struct sh_wdt {
82 void __iomem *base;
83 struct device *dev;
84
85 struct timer_list timer;
86
87 unsigned long enabled;
88 char expect_close;
89 };
90
sh_wdt_start(struct sh_wdt * wdt)91 static void sh_wdt_start(struct sh_wdt *wdt)
92 {
93 unsigned long flags;
94 u8 csr;
95
96 spin_lock_irqsave(&shwdt_lock, flags);
97
98 next_heartbeat = jiffies + (heartbeat * HZ);
99 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
100
101 csr = sh_wdt_read_csr();
102 csr |= WTCSR_WT | clock_division_ratio;
103 sh_wdt_write_csr(csr);
104
105 sh_wdt_write_cnt(0);
106
107 /*
108 * These processors have a bit of an inconsistent initialization
109 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
110 * RSTCSR register was removed.
111 *
112 * On the SH-2 however, in addition with bits being in different
113 * locations, we must deal with RSTCSR outright..
114 */
115 csr = sh_wdt_read_csr();
116 csr |= WTCSR_TME;
117 csr &= ~WTCSR_RSTS;
118 sh_wdt_write_csr(csr);
119
120 #ifdef CONFIG_CPU_SH2
121 csr = sh_wdt_read_rstcsr();
122 csr &= ~RSTCSR_RSTS;
123 sh_wdt_write_rstcsr(csr);
124 #endif
125 spin_unlock_irqrestore(&shwdt_lock, flags);
126 }
127
sh_wdt_stop(struct sh_wdt * wdt)128 static void sh_wdt_stop(struct sh_wdt *wdt)
129 {
130 unsigned long flags;
131 u8 csr;
132
133 spin_lock_irqsave(&shwdt_lock, flags);
134
135 del_timer(&wdt->timer);
136
137 csr = sh_wdt_read_csr();
138 csr &= ~WTCSR_TME;
139 sh_wdt_write_csr(csr);
140
141 spin_unlock_irqrestore(&shwdt_lock, flags);
142 }
143
sh_wdt_keepalive(struct sh_wdt * wdt)144 static inline void sh_wdt_keepalive(struct sh_wdt *wdt)
145 {
146 unsigned long flags;
147
148 spin_lock_irqsave(&shwdt_lock, flags);
149 next_heartbeat = jiffies + (heartbeat * HZ);
150 spin_unlock_irqrestore(&shwdt_lock, flags);
151 }
152
sh_wdt_set_heartbeat(int t)153 static int sh_wdt_set_heartbeat(int t)
154 {
155 unsigned long flags;
156
157 if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
158 return -EINVAL;
159
160 spin_lock_irqsave(&shwdt_lock, flags);
161 heartbeat = t;
162 spin_unlock_irqrestore(&shwdt_lock, flags);
163 return 0;
164 }
165
sh_wdt_ping(unsigned long data)166 static void sh_wdt_ping(unsigned long data)
167 {
168 struct sh_wdt *wdt = (struct sh_wdt *)data;
169 unsigned long flags;
170
171 spin_lock_irqsave(&shwdt_lock, flags);
172 if (time_before(jiffies, next_heartbeat)) {
173 u8 csr;
174
175 csr = sh_wdt_read_csr();
176 csr &= ~WTCSR_IOVF;
177 sh_wdt_write_csr(csr);
178
179 sh_wdt_write_cnt(0);
180
181 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
182 } else
183 dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
184 "the watchdog\n");
185 spin_unlock_irqrestore(&shwdt_lock, flags);
186 }
187
sh_wdt_open(struct inode * inode,struct file * file)188 static int sh_wdt_open(struct inode *inode, struct file *file)
189 {
190 struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
191
192 if (test_and_set_bit(0, &wdt->enabled))
193 return -EBUSY;
194 if (nowayout)
195 __module_get(THIS_MODULE);
196
197 file->private_data = wdt;
198
199 sh_wdt_start(wdt);
200
201 return nonseekable_open(inode, file);
202 }
203
sh_wdt_close(struct inode * inode,struct file * file)204 static int sh_wdt_close(struct inode *inode, struct file *file)
205 {
206 struct sh_wdt *wdt = file->private_data;
207
208 if (wdt->expect_close == 42) {
209 sh_wdt_stop(wdt);
210 } else {
211 dev_crit(wdt->dev, "Unexpected close, not "
212 "stopping watchdog!\n");
213 sh_wdt_keepalive(wdt);
214 }
215
216 clear_bit(0, &wdt->enabled);
217 wdt->expect_close = 0;
218
219 return 0;
220 }
221
sh_wdt_write(struct file * file,const char * buf,size_t count,loff_t * ppos)222 static ssize_t sh_wdt_write(struct file *file, const char *buf,
223 size_t count, loff_t *ppos)
224 {
225 struct sh_wdt *wdt = file->private_data;
226
227 if (count) {
228 if (!nowayout) {
229 size_t i;
230
231 wdt->expect_close = 0;
232
233 for (i = 0; i != count; i++) {
234 char c;
235 if (get_user(c, buf + i))
236 return -EFAULT;
237 if (c == 'V')
238 wdt->expect_close = 42;
239 }
240 }
241 sh_wdt_keepalive(wdt);
242 }
243
244 return count;
245 }
246
sh_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)247 static long sh_wdt_ioctl(struct file *file, unsigned int cmd,
248 unsigned long arg)
249 {
250 struct sh_wdt *wdt = file->private_data;
251 int new_heartbeat;
252 int options, retval = -EINVAL;
253
254 switch (cmd) {
255 case WDIOC_GETSUPPORT:
256 return copy_to_user((struct watchdog_info *)arg,
257 &sh_wdt_info, sizeof(sh_wdt_info)) ? -EFAULT : 0;
258 case WDIOC_GETSTATUS:
259 case WDIOC_GETBOOTSTATUS:
260 return put_user(0, (int *)arg);
261 case WDIOC_SETOPTIONS:
262 if (get_user(options, (int *)arg))
263 return -EFAULT;
264
265 if (options & WDIOS_DISABLECARD) {
266 sh_wdt_stop(wdt);
267 retval = 0;
268 }
269
270 if (options & WDIOS_ENABLECARD) {
271 sh_wdt_start(wdt);
272 retval = 0;
273 }
274
275 return retval;
276 case WDIOC_KEEPALIVE:
277 sh_wdt_keepalive(wdt);
278 return 0;
279 case WDIOC_SETTIMEOUT:
280 if (get_user(new_heartbeat, (int *)arg))
281 return -EFAULT;
282
283 if (sh_wdt_set_heartbeat(new_heartbeat))
284 return -EINVAL;
285
286 sh_wdt_keepalive(wdt);
287 /* Fall */
288 case WDIOC_GETTIMEOUT:
289 return put_user(heartbeat, (int *)arg);
290 default:
291 return -ENOTTY;
292 }
293 return 0;
294 }
295
sh_wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)296 static int sh_wdt_notify_sys(struct notifier_block *this,
297 unsigned long code, void *unused)
298 {
299 struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
300
301 if (code == SYS_DOWN || code == SYS_HALT)
302 sh_wdt_stop(wdt);
303
304 return NOTIFY_DONE;
305 }
306
307 static const struct file_operations sh_wdt_fops = {
308 .owner = THIS_MODULE,
309 .llseek = no_llseek,
310 .write = sh_wdt_write,
311 .unlocked_ioctl = sh_wdt_ioctl,
312 .open = sh_wdt_open,
313 .release = sh_wdt_close,
314 };
315
316 static const struct watchdog_info sh_wdt_info = {
317 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
318 WDIOF_MAGICCLOSE,
319 .firmware_version = 1,
320 .identity = "SH WDT",
321 };
322
323 static struct notifier_block sh_wdt_notifier = {
324 .notifier_call = sh_wdt_notify_sys,
325 };
326
327 static struct miscdevice sh_wdt_miscdev = {
328 .minor = WATCHDOG_MINOR,
329 .name = "watchdog",
330 .fops = &sh_wdt_fops,
331 };
332
sh_wdt_probe(struct platform_device * pdev)333 static int __devinit sh_wdt_probe(struct platform_device *pdev)
334 {
335 struct sh_wdt *wdt;
336 struct resource *res;
337 int rc;
338
339 /*
340 * As this driver only covers the global watchdog case, reject
341 * any attempts to register per-CPU watchdogs.
342 */
343 if (pdev->id != -1)
344 return -EINVAL;
345
346 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
347 if (unlikely(!res))
348 return -EINVAL;
349
350 if (!devm_request_mem_region(&pdev->dev, res->start,
351 resource_size(res), DRV_NAME))
352 return -EBUSY;
353
354 wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
355 if (unlikely(!wdt)) {
356 rc = -ENOMEM;
357 goto out_release;
358 }
359
360 wdt->dev = &pdev->dev;
361
362 wdt->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
363 if (unlikely(!wdt->base)) {
364 rc = -ENXIO;
365 goto out_err;
366 }
367
368 rc = register_reboot_notifier(&sh_wdt_notifier);
369 if (unlikely(rc)) {
370 dev_err(&pdev->dev,
371 "Can't register reboot notifier (err=%d)\n", rc);
372 goto out_unmap;
373 }
374
375 sh_wdt_miscdev.parent = wdt->dev;
376
377 rc = misc_register(&sh_wdt_miscdev);
378 if (unlikely(rc)) {
379 dev_err(&pdev->dev,
380 "Can't register miscdev on minor=%d (err=%d)\n",
381 sh_wdt_miscdev.minor, rc);
382 goto out_unreg;
383 }
384
385 init_timer(&wdt->timer);
386 wdt->timer.function = sh_wdt_ping;
387 wdt->timer.data = (unsigned long)wdt;
388 wdt->timer.expires = next_ping_period(clock_division_ratio);
389
390 platform_set_drvdata(pdev, wdt);
391 sh_wdt_dev = pdev;
392
393 dev_info(&pdev->dev, "initialized.\n");
394
395 return 0;
396
397 out_unreg:
398 unregister_reboot_notifier(&sh_wdt_notifier);
399 out_unmap:
400 devm_iounmap(&pdev->dev, wdt->base);
401 out_err:
402 devm_kfree(&pdev->dev, wdt);
403 out_release:
404 devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
405
406 return rc;
407 }
408
sh_wdt_remove(struct platform_device * pdev)409 static int __devexit sh_wdt_remove(struct platform_device *pdev)
410 {
411 struct sh_wdt *wdt = platform_get_drvdata(pdev);
412 struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
413
414 platform_set_drvdata(pdev, NULL);
415
416 misc_deregister(&sh_wdt_miscdev);
417
418 sh_wdt_dev = NULL;
419
420 unregister_reboot_notifier(&sh_wdt_notifier);
421 devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
422 devm_iounmap(&pdev->dev, wdt->base);
423 devm_kfree(&pdev->dev, wdt);
424
425 return 0;
426 }
427
428 static struct platform_driver sh_wdt_driver = {
429 .driver = {
430 .name = DRV_NAME,
431 .owner = THIS_MODULE,
432 },
433
434 .probe = sh_wdt_probe,
435 .remove = __devexit_p(sh_wdt_remove),
436 };
437
sh_wdt_init(void)438 static int __init sh_wdt_init(void)
439 {
440 int rc;
441
442 if (unlikely(clock_division_ratio < 0x5 ||
443 clock_division_ratio > 0x7)) {
444 clock_division_ratio = WTCSR_CKS_4096;
445
446 pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
447 clock_division_ratio);
448 }
449
450 rc = sh_wdt_set_heartbeat(heartbeat);
451 if (unlikely(rc)) {
452 heartbeat = WATCHDOG_HEARTBEAT;
453
454 pr_info("heartbeat value must be 1<=x<=3600, using %d\n",
455 heartbeat);
456 }
457
458 pr_info("configured with heartbeat=%d sec (nowayout=%d)\n",
459 heartbeat, nowayout);
460
461 return platform_driver_register(&sh_wdt_driver);
462 }
463
sh_wdt_exit(void)464 static void __exit sh_wdt_exit(void)
465 {
466 platform_driver_unregister(&sh_wdt_driver);
467 }
468 module_init(sh_wdt_init);
469 module_exit(sh_wdt_exit);
470
471 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
472 MODULE_DESCRIPTION("SuperH watchdog driver");
473 MODULE_LICENSE("GPL");
474 MODULE_ALIAS("platform:" DRV_NAME);
475 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
476
477 module_param(clock_division_ratio, int, 0);
478 MODULE_PARM_DESC(clock_division_ratio,
479 "Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
480 "to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");
481
482 module_param(heartbeat, int, 0);
483 MODULE_PARM_DESC(heartbeat,
484 "Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
485 __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
486
487 module_param(nowayout, bool, 0);
488 MODULE_PARM_DESC(nowayout,
489 "Watchdog cannot be stopped once started (default="
490 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
491