Merge branch 'bsg' of git://git.kernel.dk/data/git/linux-2.6-block
[linux-2.6.git] / drivers / char / watchdog / s3c2410_wdt.c
1 /* linux/drivers/char/watchdog/s3c2410_wdt.c
2  *
3  * Copyright (c) 2004 Simtec Electronics
4  *      Ben Dooks <ben@simtec.co.uk>
5  *
6  * S3C2410 Watchdog Timer Support
7  *
8  * Based on, softdog.c by Alan Cox,
9  *     (c) Copyright 1996 Alan Cox <alan@redhat.com>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
24  *
25  * Changelog:
26  *      05-Oct-2004     BJD     Added semaphore init to stop crashes on open
27  *                              Fixed tmr_count / wdt_count confusion
28  *                              Added configurable debug
29  *
30  *      11-Jan-2005     BJD     Fixed divide-by-2 in timeout code
31  *
32  *      25-Jan-2005     DA      Added suspend/resume support
33  *                              Replaced reboot notifier with .shutdown method
34  *
35  *      10-Mar-2005     LCVR    Changed S3C2410_VA to S3C24XX_VA
36 */
37
38 #include <linux/module.h>
39 #include <linux/moduleparam.h>
40 #include <linux/types.h>
41 #include <linux/timer.h>
42 #include <linux/miscdevice.h>
43 #include <linux/watchdog.h>
44 #include <linux/fs.h>
45 #include <linux/init.h>
46 #include <linux/platform_device.h>
47 #include <linux/interrupt.h>
48 #include <linux/clk.h>
49
50 #include <asm/uaccess.h>
51 #include <asm/io.h>
52
53 #include <asm/arch/map.h>
54
55 #undef S3C24XX_VA_WATCHDOG
56 #define S3C24XX_VA_WATCHDOG (0)
57
58 #include <asm/arch/regs-watchdog.h>
59
60 #define PFX "s3c2410-wdt: "
61
62 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
63 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
64
65 static int nowayout     = WATCHDOG_NOWAYOUT;
66 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
67 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
68 static int soft_noboot  = 0;
69 static int debug        = 0;
70
71 module_param(tmr_margin,  int, 0);
72 module_param(tmr_atboot,  int, 0);
73 module_param(nowayout,    int, 0);
74 module_param(soft_noboot, int, 0);
75 module_param(debug,       int, 0);
76
77 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
78
79 MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
80
81 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
82
83 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
84
85 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
86
87
88 typedef enum close_state {
89         CLOSE_STATE_NOT,
90         CLOSE_STATE_ALLOW=0x4021
91 } close_state_t;
92
93 static DECLARE_MUTEX(open_lock);
94
95 static struct resource  *wdt_mem;
96 static struct resource  *wdt_irq;
97 static struct clk       *wdt_clock;
98 static void __iomem     *wdt_base;
99 static unsigned int      wdt_count;
100 static close_state_t     allow_close;
101
102 /* watchdog control routines */
103
104 #define DBG(msg...) do { \
105         if (debug) \
106                 printk(KERN_INFO msg); \
107         } while(0)
108
109 /* functions */
110
111 static int s3c2410wdt_keepalive(void)
112 {
113         writel(wdt_count, wdt_base + S3C2410_WTCNT);
114         return 0;
115 }
116
117 static int s3c2410wdt_stop(void)
118 {
119         unsigned long wtcon;
120
121         wtcon = readl(wdt_base + S3C2410_WTCON);
122         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
123         writel(wtcon, wdt_base + S3C2410_WTCON);
124
125         return 0;
126 }
127
128 static int s3c2410wdt_start(void)
129 {
130         unsigned long wtcon;
131
132         s3c2410wdt_stop();
133
134         wtcon = readl(wdt_base + S3C2410_WTCON);
135         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
136
137         if (soft_noboot) {
138                 wtcon |= S3C2410_WTCON_INTEN;
139                 wtcon &= ~S3C2410_WTCON_RSTEN;
140         } else {
141                 wtcon &= ~S3C2410_WTCON_INTEN;
142                 wtcon |= S3C2410_WTCON_RSTEN;
143         }
144
145         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
146             __FUNCTION__, wdt_count, wtcon);
147
148         writel(wdt_count, wdt_base + S3C2410_WTDAT);
149         writel(wdt_count, wdt_base + S3C2410_WTCNT);
150         writel(wtcon, wdt_base + S3C2410_WTCON);
151
152         return 0;
153 }
154
155 static int s3c2410wdt_set_heartbeat(int timeout)
156 {
157         unsigned int freq = clk_get_rate(wdt_clock);
158         unsigned int count;
159         unsigned int divisor = 1;
160         unsigned long wtcon;
161
162         if (timeout < 1)
163                 return -EINVAL;
164
165         freq /= 128;
166         count = timeout * freq;
167
168         DBG("%s: count=%d, timeout=%d, freq=%d\n",
169             __FUNCTION__, count, timeout, freq);
170
171         /* if the count is bigger than the watchdog register,
172            then work out what we need to do (and if) we can
173            actually make this value
174         */
175
176         if (count >= 0x10000) {
177                 for (divisor = 1; divisor <= 0x100; divisor++) {
178                         if ((count / divisor) < 0x10000)
179                                 break;
180                 }
181
182                 if ((count / divisor) >= 0x10000) {
183                         printk(KERN_ERR PFX "timeout %d too big\n", timeout);
184                         return -EINVAL;
185                 }
186         }
187
188         tmr_margin = timeout;
189
190         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
191             __FUNCTION__, timeout, divisor, count, count/divisor);
192
193         count /= divisor;
194         wdt_count = count;
195
196         /* update the pre-scaler */
197         wtcon = readl(wdt_base + S3C2410_WTCON);
198         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
199         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
200
201         writel(count, wdt_base + S3C2410_WTDAT);
202         writel(wtcon, wdt_base + S3C2410_WTCON);
203
204         return 0;
205 }
206
207 /*
208  *      /dev/watchdog handling
209  */
210
211 static int s3c2410wdt_open(struct inode *inode, struct file *file)
212 {
213         if(down_trylock(&open_lock))
214                 return -EBUSY;
215
216         if (nowayout)
217                 __module_get(THIS_MODULE);
218
219         allow_close = CLOSE_STATE_NOT;
220
221         /* start the timer */
222         s3c2410wdt_start();
223         return nonseekable_open(inode, file);
224 }
225
226 static int s3c2410wdt_release(struct inode *inode, struct file *file)
227 {
228         /*
229          *      Shut off the timer.
230          *      Lock it in if it's a module and we set nowayout
231          */
232
233         if (allow_close == CLOSE_STATE_ALLOW) {
234                 s3c2410wdt_stop();
235         } else {
236                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
237                 s3c2410wdt_keepalive();
238         }
239
240         allow_close = CLOSE_STATE_NOT;
241         up(&open_lock);
242         return 0;
243 }
244
245 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
246                                 size_t len, loff_t *ppos)
247 {
248         /*
249          *      Refresh the timer.
250          */
251         if(len) {
252                 if (!nowayout) {
253                         size_t i;
254
255                         /* In case it was set long ago */
256                         allow_close = CLOSE_STATE_NOT;
257
258                         for (i = 0; i != len; i++) {
259                                 char c;
260
261                                 if (get_user(c, data + i))
262                                         return -EFAULT;
263                                 if (c == 'V')
264                                         allow_close = CLOSE_STATE_ALLOW;
265                         }
266                 }
267
268                 s3c2410wdt_keepalive();
269         }
270         return len;
271 }
272
273 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
274
275 static struct watchdog_info s3c2410_wdt_ident = {
276         .options          =     OPTIONS,
277         .firmware_version =     0,
278         .identity         =     "S3C2410 Watchdog",
279 };
280
281
282 static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
283         unsigned int cmd, unsigned long arg)
284 {
285         void __user *argp = (void __user *)arg;
286         int __user *p = argp;
287         int new_margin;
288
289         switch (cmd) {
290                 default:
291                         return -ENOTTY;
292
293                 case WDIOC_GETSUPPORT:
294                         return copy_to_user(argp, &s3c2410_wdt_ident,
295                                 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
296
297                 case WDIOC_GETSTATUS:
298                 case WDIOC_GETBOOTSTATUS:
299                         return put_user(0, p);
300
301                 case WDIOC_KEEPALIVE:
302                         s3c2410wdt_keepalive();
303                         return 0;
304
305                 case WDIOC_SETTIMEOUT:
306                         if (get_user(new_margin, p))
307                                 return -EFAULT;
308
309                         if (s3c2410wdt_set_heartbeat(new_margin))
310                                 return -EINVAL;
311
312                         s3c2410wdt_keepalive();
313                         return put_user(tmr_margin, p);
314
315                 case WDIOC_GETTIMEOUT:
316                         return put_user(tmr_margin, p);
317         }
318 }
319
320 /* kernel interface */
321
322 static const struct file_operations s3c2410wdt_fops = {
323         .owner          = THIS_MODULE,
324         .llseek         = no_llseek,
325         .write          = s3c2410wdt_write,
326         .ioctl          = s3c2410wdt_ioctl,
327         .open           = s3c2410wdt_open,
328         .release        = s3c2410wdt_release,
329 };
330
331 static struct miscdevice s3c2410wdt_miscdev = {
332         .minor          = WATCHDOG_MINOR,
333         .name           = "watchdog",
334         .fops           = &s3c2410wdt_fops,
335 };
336
337 /* interrupt handler code */
338
339 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
340 {
341         printk(KERN_INFO PFX "Watchdog timer expired!\n");
342
343         s3c2410wdt_keepalive();
344         return IRQ_HANDLED;
345 }
346 /* device interface */
347
348 static int s3c2410wdt_probe(struct platform_device *pdev)
349 {
350         struct resource *res;
351         int started = 0;
352         int ret;
353         int size;
354
355         DBG("%s: probe=%p\n", __FUNCTION__, pdev);
356
357         /* get the memory region for the watchdog timer */
358
359         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
360         if (res == NULL) {
361                 printk(KERN_INFO PFX "failed to get memory region resouce\n");
362                 return -ENOENT;
363         }
364
365         size = (res->end-res->start)+1;
366         wdt_mem = request_mem_region(res->start, size, pdev->name);
367         if (wdt_mem == NULL) {
368                 printk(KERN_INFO PFX "failed to get memory region\n");
369                 ret = -ENOENT;
370                 goto err_req;
371         }
372
373         wdt_base = ioremap(res->start, size);
374         if (wdt_base == 0) {
375                 printk(KERN_INFO PFX "failed to ioremap() region\n");
376                 ret = -EINVAL;
377                 goto err_req;
378         }
379
380         DBG("probe: mapped wdt_base=%p\n", wdt_base);
381
382         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
383         if (wdt_irq == NULL) {
384                 printk(KERN_INFO PFX "failed to get irq resource\n");
385                 ret = -ENOENT;
386                 goto err_map;
387         }
388
389         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
390         if (ret != 0) {
391                 printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
392                 goto err_map;
393         }
394
395         wdt_clock = clk_get(&pdev->dev, "watchdog");
396         if (IS_ERR(wdt_clock)) {
397                 printk(KERN_INFO PFX "failed to find watchdog clock source\n");
398                 ret = PTR_ERR(wdt_clock);
399                 goto err_irq;
400         }
401
402         clk_enable(wdt_clock);
403
404         /* see if we can actually set the requested timer margin, and if
405          * not, try the default value */
406
407         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
408                 started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
409
410                 if (started == 0) {
411                         printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
412                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
413                 } else {
414                         printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
415                 }
416         }
417
418         ret = misc_register(&s3c2410wdt_miscdev);
419         if (ret) {
420                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
421                         WATCHDOG_MINOR, ret);
422                 goto err_clk;
423         }
424
425         if (tmr_atboot && started == 0) {
426                 printk(KERN_INFO PFX "Starting Watchdog Timer\n");
427                 s3c2410wdt_start();
428         } else if (!tmr_atboot) {
429                 /* if we're not enabling the watchdog, then ensure it is
430                  * disabled if it has been left running from the bootloader
431                  * or other source */
432
433                 s3c2410wdt_stop();
434         }
435
436         return 0;
437
438  err_clk:
439         clk_disable(wdt_clock);
440         clk_put(wdt_clock);
441
442  err_irq:
443         free_irq(wdt_irq->start, pdev);
444
445  err_map:
446         iounmap(wdt_base);
447
448  err_req:
449         release_resource(wdt_mem);
450         kfree(wdt_mem);
451
452         return ret;
453 }
454
455 static int s3c2410wdt_remove(struct platform_device *dev)
456 {
457         release_resource(wdt_mem);
458         kfree(wdt_mem);
459         wdt_mem = NULL;
460
461         free_irq(wdt_irq->start, dev);
462         wdt_irq = NULL;
463
464         clk_disable(wdt_clock);
465         clk_put(wdt_clock);
466         wdt_clock = NULL;
467
468         iounmap(wdt_base);
469         misc_deregister(&s3c2410wdt_miscdev);
470         return 0;
471 }
472
473 static void s3c2410wdt_shutdown(struct platform_device *dev)
474 {
475         s3c2410wdt_stop();      
476 }
477
478 #ifdef CONFIG_PM
479
480 static unsigned long wtcon_save;
481 static unsigned long wtdat_save;
482
483 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
484 {
485         /* Save watchdog state, and turn it off. */
486         wtcon_save = readl(wdt_base + S3C2410_WTCON);
487         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
488
489         /* Note that WTCNT doesn't need to be saved. */
490         s3c2410wdt_stop();
491
492         return 0;
493 }
494
495 static int s3c2410wdt_resume(struct platform_device *dev)
496 {
497         /* Restore watchdog state. */
498
499         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
500         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
501         writel(wtcon_save, wdt_base + S3C2410_WTCON);
502
503         printk(KERN_INFO PFX "watchdog %sabled\n",
504                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
505
506         return 0;
507 }
508
509 #else
510 #define s3c2410wdt_suspend NULL
511 #define s3c2410wdt_resume  NULL
512 #endif /* CONFIG_PM */
513
514
515 static struct platform_driver s3c2410wdt_driver = {
516         .probe          = s3c2410wdt_probe,
517         .remove         = s3c2410wdt_remove,
518         .shutdown       = s3c2410wdt_shutdown,
519         .suspend        = s3c2410wdt_suspend,
520         .resume         = s3c2410wdt_resume,
521         .driver         = {
522                 .owner  = THIS_MODULE,
523                 .name   = "s3c2410-wdt",
524         },
525 };
526
527
528 static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
529
530 static int __init watchdog_init(void)
531 {
532         printk(banner);
533         return platform_driver_register(&s3c2410wdt_driver);
534 }
535
536 static void __exit watchdog_exit(void)
537 {
538         platform_driver_unregister(&s3c2410wdt_driver);
539 }
540
541 module_init(watchdog_init);
542 module_exit(watchdog_exit);
543
544 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
545               "Dimitry Andric <dimitry.andric@tomtom.com>");
546 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
547 MODULE_LICENSE("GPL");
548 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);