media: soc_camera: tegra: fix one building warning
[linux-2.6.git] / drivers / watchdog / shwdt.c
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 #include <linux/module.h>
21 #include <linux/moduleparam.h>
22 #include <linux/platform_device.h>
23 #include <linux/init.h>
24 #include <linux/types.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
27 #include <linux/reboot.h>
28 #include <linux/notifier.h>
29 #include <linux/ioport.h>
30 #include <linux/fs.h>
31 #include <linux/mm.h>
32 #include <linux/slab.h>
33 #include <linux/io.h>
34 #include <linux/uaccess.h>
35 #include <asm/watchdog.h>
36
37 #define DRV_NAME "sh-wdt"
38
39 /*
40  * Default clock division ratio is 5.25 msecs. For an additional table of
41  * values, consult the asm-sh/watchdog.h. Overload this at module load
42  * time.
43  *
44  * In order for this to work reliably we need to have HZ set to 1000 or
45  * something quite higher than 100 (or we need a proper high-res timer
46  * implementation that will deal with this properly), otherwise the 10ms
47  * resolution of a jiffy is enough to trigger the overflow. For things like
48  * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
49  * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
50  * necssary.
51  *
52  * As a result of this timing problem, the only modes that are particularly
53  * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
54  * overflow periods respectively.
55  *
56  * Also, since we can't really expect userspace to be responsive enough
57  * before the overflow happens, we maintain two separate timers .. One in
58  * the kernel for clearing out WOVF every 2ms or so (again, this depends on
59  * HZ == 1000), and another for monitoring userspace writes to the WDT device.
60  *
61  * As such, we currently use a configurable heartbeat interval which defaults
62  * to 30s. In this case, the userspace daemon is only responsible for periodic
63  * writes to the device before the next heartbeat is scheduled. If the daemon
64  * misses its deadline, the kernel timer will allow the WDT to overflow.
65  */
66 static int clock_division_ratio = WTCSR_CKS_4096;
67 #define next_ping_period(cks)   (jiffies + msecs_to_jiffies(cks - 4))
68
69 static const struct watchdog_info sh_wdt_info;
70 static struct platform_device *sh_wdt_dev;
71 static DEFINE_SPINLOCK(shwdt_lock);
72
73 #define WATCHDOG_HEARTBEAT 30                   /* 30 sec default heartbeat */
74 static int heartbeat = WATCHDOG_HEARTBEAT;      /* in seconds */
75 static int nowayout = WATCHDOG_NOWAYOUT;
76 static unsigned long next_heartbeat;
77
78 struct sh_wdt {
79         void __iomem            *base;
80         struct device           *dev;
81
82         struct timer_list       timer;
83
84         unsigned long           enabled;
85         char                    expect_close;
86 };
87
88 static void sh_wdt_start(struct sh_wdt *wdt)
89 {
90         unsigned long flags;
91         u8 csr;
92
93         spin_lock_irqsave(&shwdt_lock, flags);
94
95         next_heartbeat = jiffies + (heartbeat * HZ);
96         mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
97
98         csr = sh_wdt_read_csr();
99         csr |= WTCSR_WT | clock_division_ratio;
100         sh_wdt_write_csr(csr);
101
102         sh_wdt_write_cnt(0);
103
104         /*
105          * These processors have a bit of an inconsistent initialization
106          * process.. starting with SH-3, RSTS was moved to WTCSR, and the
107          * RSTCSR register was removed.
108          *
109          * On the SH-2 however, in addition with bits being in different
110          * locations, we must deal with RSTCSR outright..
111          */
112         csr = sh_wdt_read_csr();
113         csr |= WTCSR_TME;
114         csr &= ~WTCSR_RSTS;
115         sh_wdt_write_csr(csr);
116
117 #ifdef CONFIG_CPU_SH2
118         csr = sh_wdt_read_rstcsr();
119         csr &= ~RSTCSR_RSTS;
120         sh_wdt_write_rstcsr(csr);
121 #endif
122         spin_unlock_irqrestore(&shwdt_lock, flags);
123 }
124
125 static void sh_wdt_stop(struct sh_wdt *wdt)
126 {
127         unsigned long flags;
128         u8 csr;
129
130         spin_lock_irqsave(&shwdt_lock, flags);
131
132         del_timer(&wdt->timer);
133
134         csr = sh_wdt_read_csr();
135         csr &= ~WTCSR_TME;
136         sh_wdt_write_csr(csr);
137
138         spin_unlock_irqrestore(&shwdt_lock, flags);
139 }
140
141 static inline void sh_wdt_keepalive(struct sh_wdt *wdt)
142 {
143         unsigned long flags;
144
145         spin_lock_irqsave(&shwdt_lock, flags);
146         next_heartbeat = jiffies + (heartbeat * HZ);
147         spin_unlock_irqrestore(&shwdt_lock, flags);
148 }
149
150 static int sh_wdt_set_heartbeat(int t)
151 {
152         unsigned long flags;
153
154         if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
155                 return -EINVAL;
156
157         spin_lock_irqsave(&shwdt_lock, flags);
158         heartbeat = t;
159         spin_unlock_irqrestore(&shwdt_lock, flags);
160         return 0;
161 }
162
163 static void sh_wdt_ping(unsigned long data)
164 {
165         struct sh_wdt *wdt = (struct sh_wdt *)data;
166         unsigned long flags;
167
168         spin_lock_irqsave(&shwdt_lock, flags);
169         if (time_before(jiffies, next_heartbeat)) {
170                 u8 csr;
171
172                 csr = sh_wdt_read_csr();
173                 csr &= ~WTCSR_IOVF;
174                 sh_wdt_write_csr(csr);
175
176                 sh_wdt_write_cnt(0);
177
178                 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
179         } else
180                 dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
181                          "the watchdog\n");
182         spin_unlock_irqrestore(&shwdt_lock, flags);
183 }
184
185 static int sh_wdt_open(struct inode *inode, struct file *file)
186 {
187         struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
188
189         if (test_and_set_bit(0, &wdt->enabled))
190                 return -EBUSY;
191         if (nowayout)
192                 __module_get(THIS_MODULE);
193
194         file->private_data = wdt;
195
196         sh_wdt_start(wdt);
197
198         return nonseekable_open(inode, file);
199 }
200
201 static int sh_wdt_close(struct inode *inode, struct file *file)
202 {
203         struct sh_wdt *wdt = file->private_data;
204
205         if (wdt->expect_close == 42) {
206                 sh_wdt_stop(wdt);
207         } else {
208                 dev_crit(wdt->dev, "Unexpected close, not "
209                          "stopping watchdog!\n");
210                 sh_wdt_keepalive(wdt);
211         }
212
213         clear_bit(0, &wdt->enabled);
214         wdt->expect_close = 0;
215
216         return 0;
217 }
218
219 static ssize_t sh_wdt_write(struct file *file, const char *buf,
220                             size_t count, loff_t *ppos)
221 {
222         struct sh_wdt *wdt = file->private_data;
223
224         if (count) {
225                 if (!nowayout) {
226                         size_t i;
227
228                         wdt->expect_close = 0;
229
230                         for (i = 0; i != count; i++) {
231                                 char c;
232                                 if (get_user(c, buf + i))
233                                         return -EFAULT;
234                                 if (c == 'V')
235                                         wdt->expect_close = 42;
236                         }
237                 }
238                 sh_wdt_keepalive(wdt);
239         }
240
241         return count;
242 }
243
244 static long sh_wdt_ioctl(struct file *file, unsigned int cmd,
245                                                         unsigned long arg)
246 {
247         struct sh_wdt *wdt = file->private_data;
248         int new_heartbeat;
249         int options, retval = -EINVAL;
250
251         switch (cmd) {
252         case WDIOC_GETSUPPORT:
253                 return copy_to_user((struct watchdog_info *)arg,
254                           &sh_wdt_info, sizeof(sh_wdt_info)) ? -EFAULT : 0;
255         case WDIOC_GETSTATUS:
256         case WDIOC_GETBOOTSTATUS:
257                 return put_user(0, (int *)arg);
258         case WDIOC_SETOPTIONS:
259                 if (get_user(options, (int *)arg))
260                         return -EFAULT;
261
262                 if (options & WDIOS_DISABLECARD) {
263                         sh_wdt_stop(wdt);
264                         retval = 0;
265                 }
266
267                 if (options & WDIOS_ENABLECARD) {
268                         sh_wdt_start(wdt);
269                         retval = 0;
270                 }
271
272                 return retval;
273         case WDIOC_KEEPALIVE:
274                 sh_wdt_keepalive(wdt);
275                 return 0;
276         case WDIOC_SETTIMEOUT:
277                 if (get_user(new_heartbeat, (int *)arg))
278                         return -EFAULT;
279
280                 if (sh_wdt_set_heartbeat(new_heartbeat))
281                         return -EINVAL;
282
283                 sh_wdt_keepalive(wdt);
284                 /* Fall */
285         case WDIOC_GETTIMEOUT:
286                 return put_user(heartbeat, (int *)arg);
287         default:
288                 return -ENOTTY;
289         }
290         return 0;
291 }
292
293 static int sh_wdt_notify_sys(struct notifier_block *this,
294                              unsigned long code, void *unused)
295 {
296         struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
297
298         if (code == SYS_DOWN || code == SYS_HALT)
299                 sh_wdt_stop(wdt);
300
301         return NOTIFY_DONE;
302 }
303
304 static const struct file_operations sh_wdt_fops = {
305         .owner          = THIS_MODULE,
306         .llseek         = no_llseek,
307         .write          = sh_wdt_write,
308         .unlocked_ioctl = sh_wdt_ioctl,
309         .open           = sh_wdt_open,
310         .release        = sh_wdt_close,
311 };
312
313 static const struct watchdog_info sh_wdt_info = {
314         .options                = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
315                                   WDIOF_MAGICCLOSE,
316         .firmware_version       = 1,
317         .identity               = "SH WDT",
318 };
319
320 static struct notifier_block sh_wdt_notifier = {
321         .notifier_call          = sh_wdt_notify_sys,
322 };
323
324 static struct miscdevice sh_wdt_miscdev = {
325         .minor          = WATCHDOG_MINOR,
326         .name           = "watchdog",
327         .fops           = &sh_wdt_fops,
328 };
329
330 static int __devinit sh_wdt_probe(struct platform_device *pdev)
331 {
332         struct sh_wdt *wdt;
333         struct resource *res;
334         int rc;
335
336         /*
337          * As this driver only covers the global watchdog case, reject
338          * any attempts to register per-CPU watchdogs.
339          */
340         if (pdev->id != -1)
341                 return -EINVAL;
342
343         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
344         if (unlikely(!res))
345                 return -EINVAL;
346
347         if (!devm_request_mem_region(&pdev->dev, res->start,
348                                      resource_size(res), DRV_NAME))
349                 return -EBUSY;
350
351         wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
352         if (unlikely(!wdt)) {
353                 rc = -ENOMEM;
354                 goto out_release;
355         }
356
357         wdt->dev = &pdev->dev;
358
359         wdt->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
360         if (unlikely(!wdt->base)) {
361                 rc = -ENXIO;
362                 goto out_err;
363         }
364
365         rc = register_reboot_notifier(&sh_wdt_notifier);
366         if (unlikely(rc)) {
367                 dev_err(&pdev->dev,
368                         "Can't register reboot notifier (err=%d)\n", rc);
369                 goto out_unmap;
370         }
371
372         sh_wdt_miscdev.parent = wdt->dev;
373
374         rc = misc_register(&sh_wdt_miscdev);
375         if (unlikely(rc)) {
376                 dev_err(&pdev->dev,
377                         "Can't register miscdev on minor=%d (err=%d)\n",
378                                                 sh_wdt_miscdev.minor, rc);
379                 goto out_unreg;
380         }
381
382         init_timer(&wdt->timer);
383         wdt->timer.function     = sh_wdt_ping;
384         wdt->timer.data         = (unsigned long)wdt;
385         wdt->timer.expires      = next_ping_period(clock_division_ratio);
386
387         platform_set_drvdata(pdev, wdt);
388         sh_wdt_dev = pdev;
389
390         dev_info(&pdev->dev, "initialized.\n");
391
392         return 0;
393
394 out_unreg:
395         unregister_reboot_notifier(&sh_wdt_notifier);
396 out_unmap:
397         devm_iounmap(&pdev->dev, wdt->base);
398 out_err:
399         devm_kfree(&pdev->dev, wdt);
400 out_release:
401         devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
402
403         return rc;
404 }
405
406 static int __devexit sh_wdt_remove(struct platform_device *pdev)
407 {
408         struct sh_wdt *wdt = platform_get_drvdata(pdev);
409         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
410
411         platform_set_drvdata(pdev, NULL);
412
413         misc_deregister(&sh_wdt_miscdev);
414
415         sh_wdt_dev = NULL;
416
417         unregister_reboot_notifier(&sh_wdt_notifier);
418         devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
419         devm_iounmap(&pdev->dev, wdt->base);
420         devm_kfree(&pdev->dev, wdt);
421
422         return 0;
423 }
424
425 static struct platform_driver sh_wdt_driver = {
426         .driver         = {
427                 .name   = DRV_NAME,
428                 .owner  = THIS_MODULE,
429         },
430
431         .probe  = sh_wdt_probe,
432         .remove = __devexit_p(sh_wdt_remove),
433 };
434
435 static int __init sh_wdt_init(void)
436 {
437         int rc;
438
439         if (unlikely(clock_division_ratio < 0x5 ||
440                      clock_division_ratio > 0x7)) {
441                 clock_division_ratio = WTCSR_CKS_4096;
442
443                 pr_info("%s: divisor must be 0x5<=x<=0x7, using %d\n",
444                          DRV_NAME, clock_division_ratio);
445         }
446
447         rc = sh_wdt_set_heartbeat(heartbeat);
448         if (unlikely(rc)) {
449                 heartbeat = WATCHDOG_HEARTBEAT;
450
451                 pr_info("%s: heartbeat value must be 1<=x<=3600, using %d\n",
452                         DRV_NAME, heartbeat);
453         }
454
455         pr_info("%s: configured with heartbeat=%d sec (nowayout=%d)\n",
456                 DRV_NAME, heartbeat, nowayout);
457
458         return platform_driver_register(&sh_wdt_driver);
459 }
460
461 static void __exit sh_wdt_exit(void)
462 {
463         platform_driver_unregister(&sh_wdt_driver);
464 }
465 module_init(sh_wdt_init);
466 module_exit(sh_wdt_exit);
467
468 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
469 MODULE_DESCRIPTION("SuperH watchdog driver");
470 MODULE_LICENSE("GPL");
471 MODULE_ALIAS("platform:" DRV_NAME);
472 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
473
474 module_param(clock_division_ratio, int, 0);
475 MODULE_PARM_DESC(clock_division_ratio,
476         "Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
477         "to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");
478
479 module_param(heartbeat, int, 0);
480 MODULE_PARM_DESC(heartbeat,
481         "Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
482                                 __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
483
484 module_param(nowayout, int, 0);
485 MODULE_PARM_DESC(nowayout,
486         "Watchdog cannot be stopped once started (default="
487                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");