Merge git://git.kernel.org/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog
[linux-2.6] / drivers / 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@lxorguk.ukuu.org.uk>
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
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/types.h>
29 #include <linux/timer.h>
30 #include <linux/miscdevice.h>
31 #include <linux/watchdog.h>
32 #include <linux/fs.h>
33 #include <linux/init.h>
34 #include <linux/platform_device.h>
35 #include <linux/interrupt.h>
36 #include <linux/clk.h>
37 #include <linux/uaccess.h>
38 #include <linux/io.h>
39
40 #include <mach/map.h>
41
42 #undef S3C_VA_WATCHDOG
43 #define S3C_VA_WATCHDOG (0)
44
45 #include <plat/regs-watchdog.h>
46
47 #define PFX "s3c2410-wdt: "
48
49 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
50 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
51
52 static int nowayout     = WATCHDOG_NOWAYOUT;
53 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
54 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
55 static int soft_noboot;
56 static int debug;
57
58 module_param(tmr_margin,  int, 0);
59 module_param(tmr_atboot,  int, 0);
60 module_param(nowayout,    int, 0);
61 module_param(soft_noboot, int, 0);
62 module_param(debug,       int, 0);
63
64 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default="
65                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
66 MODULE_PARM_DESC(tmr_atboot,
67                 "Watchdog is started at boot time if set to 1, default="
68                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
70                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
71 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
72                         "0 to reboot (default depends on ONLY_TESTING)");
73 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
74
75 static unsigned long open_lock;
76 static struct device    *wdt_dev;       /* platform device attached to */
77 static struct resource  *wdt_mem;
78 static struct resource  *wdt_irq;
79 static struct clk       *wdt_clock;
80 static void __iomem     *wdt_base;
81 static unsigned int      wdt_count;
82 static char              expect_close;
83 static DEFINE_SPINLOCK(wdt_lock);
84
85 /* watchdog control routines */
86
87 #define DBG(msg...) do { \
88         if (debug) \
89                 printk(KERN_INFO msg); \
90         } while (0)
91
92 /* functions */
93
94 static void s3c2410wdt_keepalive(void)
95 {
96         spin_lock(&wdt_lock);
97         writel(wdt_count, wdt_base + S3C2410_WTCNT);
98         spin_unlock(&wdt_lock);
99 }
100
101 static void __s3c2410wdt_stop(void)
102 {
103         unsigned long wtcon;
104
105         wtcon = readl(wdt_base + S3C2410_WTCON);
106         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
107         writel(wtcon, wdt_base + S3C2410_WTCON);
108 }
109
110 static void s3c2410wdt_stop(void)
111 {
112         spin_lock(&wdt_lock);
113         __s3c2410wdt_stop();
114         spin_unlock(&wdt_lock);
115 }
116
117 static void s3c2410wdt_start(void)
118 {
119         unsigned long wtcon;
120
121         spin_lock(&wdt_lock);
122
123         __s3c2410wdt_stop();
124
125         wtcon = readl(wdt_base + S3C2410_WTCON);
126         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
127
128         if (soft_noboot) {
129                 wtcon |= S3C2410_WTCON_INTEN;
130                 wtcon &= ~S3C2410_WTCON_RSTEN;
131         } else {
132                 wtcon &= ~S3C2410_WTCON_INTEN;
133                 wtcon |= S3C2410_WTCON_RSTEN;
134         }
135
136         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
137             __func__, wdt_count, wtcon);
138
139         writel(wdt_count, wdt_base + S3C2410_WTDAT);
140         writel(wdt_count, wdt_base + S3C2410_WTCNT);
141         writel(wtcon, wdt_base + S3C2410_WTCON);
142         spin_unlock(&wdt_lock);
143 }
144
145 static int s3c2410wdt_set_heartbeat(int timeout)
146 {
147         unsigned int freq = clk_get_rate(wdt_clock);
148         unsigned int count;
149         unsigned int divisor = 1;
150         unsigned long wtcon;
151
152         if (timeout < 1)
153                 return -EINVAL;
154
155         freq /= 128;
156         count = timeout * freq;
157
158         DBG("%s: count=%d, timeout=%d, freq=%d\n",
159             __func__, count, timeout, freq);
160
161         /* if the count is bigger than the watchdog register,
162            then work out what we need to do (and if) we can
163            actually make this value
164         */
165
166         if (count >= 0x10000) {
167                 for (divisor = 1; divisor <= 0x100; divisor++) {
168                         if ((count / divisor) < 0x10000)
169                                 break;
170                 }
171
172                 if ((count / divisor) >= 0x10000) {
173                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
174                         return -EINVAL;
175                 }
176         }
177
178         tmr_margin = timeout;
179
180         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
181             __func__, timeout, divisor, count, count/divisor);
182
183         count /= divisor;
184         wdt_count = count;
185
186         /* update the pre-scaler */
187         wtcon = readl(wdt_base + S3C2410_WTCON);
188         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
189         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
190
191         writel(count, wdt_base + S3C2410_WTDAT);
192         writel(wtcon, wdt_base + S3C2410_WTCON);
193
194         return 0;
195 }
196
197 /*
198  *      /dev/watchdog handling
199  */
200
201 static int s3c2410wdt_open(struct inode *inode, struct file *file)
202 {
203         if (test_and_set_bit(0, &open_lock))
204                 return -EBUSY;
205
206         if (nowayout)
207                 __module_get(THIS_MODULE);
208
209         expect_close = 0;
210
211         /* start the timer */
212         s3c2410wdt_start();
213         return nonseekable_open(inode, file);
214 }
215
216 static int s3c2410wdt_release(struct inode *inode, struct file *file)
217 {
218         /*
219          *      Shut off the timer.
220          *      Lock it in if it's a module and we set nowayout
221          */
222
223         if (expect_close == 42)
224                 s3c2410wdt_stop();
225         else {
226                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
227                 s3c2410wdt_keepalive();
228         }
229         expect_close = 0;
230         clear_bit(0, &open_lock);
231         return 0;
232 }
233
234 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
235                                 size_t len, loff_t *ppos)
236 {
237         /*
238          *      Refresh the timer.
239          */
240         if (len) {
241                 if (!nowayout) {
242                         size_t i;
243
244                         /* In case it was set long ago */
245                         expect_close = 0;
246
247                         for (i = 0; i != len; i++) {
248                                 char c;
249
250                                 if (get_user(c, data + i))
251                                         return -EFAULT;
252                                 if (c == 'V')
253                                         expect_close = 42;
254                         }
255                 }
256                 s3c2410wdt_keepalive();
257         }
258         return len;
259 }
260
261 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
262
263 static const struct watchdog_info s3c2410_wdt_ident = {
264         .options          =     OPTIONS,
265         .firmware_version =     0,
266         .identity         =     "S3C2410 Watchdog",
267 };
268
269
270 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
271                                                         unsigned long arg)
272 {
273         void __user *argp = (void __user *)arg;
274         int __user *p = argp;
275         int new_margin;
276
277         switch (cmd) {
278         case WDIOC_GETSUPPORT:
279                 return copy_to_user(argp, &s3c2410_wdt_ident,
280                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
281         case WDIOC_GETSTATUS:
282         case WDIOC_GETBOOTSTATUS:
283                 return put_user(0, p);
284         case WDIOC_KEEPALIVE:
285                 s3c2410wdt_keepalive();
286                 return 0;
287         case WDIOC_SETTIMEOUT:
288                 if (get_user(new_margin, p))
289                         return -EFAULT;
290                 if (s3c2410wdt_set_heartbeat(new_margin))
291                         return -EINVAL;
292                 s3c2410wdt_keepalive();
293                 return put_user(tmr_margin, p);
294         case WDIOC_GETTIMEOUT:
295                 return put_user(tmr_margin, p);
296         default:
297                 return -ENOTTY;
298         }
299 }
300
301 /* kernel interface */
302
303 static const struct file_operations s3c2410wdt_fops = {
304         .owner          = THIS_MODULE,
305         .llseek         = no_llseek,
306         .write          = s3c2410wdt_write,
307         .unlocked_ioctl = s3c2410wdt_ioctl,
308         .open           = s3c2410wdt_open,
309         .release        = s3c2410wdt_release,
310 };
311
312 static struct miscdevice s3c2410wdt_miscdev = {
313         .minor          = WATCHDOG_MINOR,
314         .name           = "watchdog",
315         .fops           = &s3c2410wdt_fops,
316 };
317
318 /* interrupt handler code */
319
320 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
321 {
322         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
323
324         s3c2410wdt_keepalive();
325         return IRQ_HANDLED;
326 }
327 /* device interface */
328
329 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
330 {
331         struct resource *res;
332         struct device *dev;
333         unsigned int wtcon;
334         int started = 0;
335         int ret;
336         int size;
337
338         DBG("%s: probe=%p\n", __func__, pdev);
339
340         dev = &pdev->dev;
341         wdt_dev = &pdev->dev;
342
343         /* get the memory region for the watchdog timer */
344
345         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
346         if (res == NULL) {
347                 dev_err(dev, "no memory resource specified\n");
348                 return -ENOENT;
349         }
350
351         size = (res->end - res->start) + 1;
352         wdt_mem = request_mem_region(res->start, size, pdev->name);
353         if (wdt_mem == NULL) {
354                 dev_err(dev, "failed to get memory region\n");
355                 ret = -ENOENT;
356                 goto err_req;
357         }
358
359         wdt_base = ioremap(res->start, size);
360         if (wdt_base == NULL) {
361                 dev_err(dev, "failed to ioremap() region\n");
362                 ret = -EINVAL;
363                 goto err_req;
364         }
365
366         DBG("probe: mapped wdt_base=%p\n", wdt_base);
367
368         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
369         if (wdt_irq == NULL) {
370                 dev_err(dev, "no irq resource specified\n");
371                 ret = -ENOENT;
372                 goto err_map;
373         }
374
375         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
376         if (ret != 0) {
377                 dev_err(dev, "failed to install irq (%d)\n", ret);
378                 goto err_map;
379         }
380
381         wdt_clock = clk_get(&pdev->dev, "watchdog");
382         if (IS_ERR(wdt_clock)) {
383                 dev_err(dev, "failed to find watchdog clock source\n");
384                 ret = PTR_ERR(wdt_clock);
385                 goto err_irq;
386         }
387
388         clk_enable(wdt_clock);
389
390         /* see if we can actually set the requested timer margin, and if
391          * not, try the default value */
392
393         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
394                 started = s3c2410wdt_set_heartbeat(
395                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
396
397                 if (started == 0)
398                         dev_info(dev,
399                            "tmr_margin value out of range, default %d used\n",
400                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
401                 else
402                         dev_info(dev, "default timer value is out of range, "
403                                                         "cannot start\n");
404         }
405
406         ret = misc_register(&s3c2410wdt_miscdev);
407         if (ret) {
408                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
409                         WATCHDOG_MINOR, ret);
410                 goto err_clk;
411         }
412
413         if (tmr_atboot && started == 0) {
414                 dev_info(dev, "starting watchdog timer\n");
415                 s3c2410wdt_start();
416         } else if (!tmr_atboot) {
417                 /* if we're not enabling the watchdog, then ensure it is
418                  * disabled if it has been left running from the bootloader
419                  * or other source */
420
421                 s3c2410wdt_stop();
422         }
423
424         /* print out a statement of readiness */
425
426         wtcon = readl(wdt_base + S3C2410_WTCON);
427
428         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
429                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
430                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
431                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
432
433         return 0;
434
435  err_clk:
436         clk_disable(wdt_clock);
437         clk_put(wdt_clock);
438
439  err_irq:
440         free_irq(wdt_irq->start, pdev);
441
442  err_map:
443         iounmap(wdt_base);
444
445  err_req:
446         release_resource(wdt_mem);
447         kfree(wdt_mem);
448
449         return ret;
450 }
451
452 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
453 {
454         release_resource(wdt_mem);
455         kfree(wdt_mem);
456         wdt_mem = NULL;
457
458         free_irq(wdt_irq->start, dev);
459         wdt_irq = NULL;
460
461         clk_disable(wdt_clock);
462         clk_put(wdt_clock);
463         wdt_clock = NULL;
464
465         iounmap(wdt_base);
466         misc_deregister(&s3c2410wdt_miscdev);
467         return 0;
468 }
469
470 static void s3c2410wdt_shutdown(struct platform_device *dev)
471 {
472         s3c2410wdt_stop();
473 }
474
475 #ifdef CONFIG_PM
476
477 static unsigned long wtcon_save;
478 static unsigned long wtdat_save;
479
480 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
481 {
482         /* Save watchdog state, and turn it off. */
483         wtcon_save = readl(wdt_base + S3C2410_WTCON);
484         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
485
486         /* Note that WTCNT doesn't need to be saved. */
487         s3c2410wdt_stop();
488
489         return 0;
490 }
491
492 static int s3c2410wdt_resume(struct platform_device *dev)
493 {
494         /* Restore watchdog state. */
495
496         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
497         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
498         writel(wtcon_save, wdt_base + S3C2410_WTCON);
499
500         printk(KERN_INFO PFX "watchdog %sabled\n",
501                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
502
503         return 0;
504 }
505
506 #else
507 #define s3c2410wdt_suspend NULL
508 #define s3c2410wdt_resume  NULL
509 #endif /* CONFIG_PM */
510
511
512 static struct platform_driver s3c2410wdt_driver = {
513         .probe          = s3c2410wdt_probe,
514         .remove         = __devexit_p(s3c2410wdt_remove),
515         .shutdown       = s3c2410wdt_shutdown,
516         .suspend        = s3c2410wdt_suspend,
517         .resume         = s3c2410wdt_resume,
518         .driver         = {
519                 .owner  = THIS_MODULE,
520                 .name   = "s3c2410-wdt",
521         },
522 };
523
524
525 static char banner[] __initdata =
526         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
527
528 static int __init watchdog_init(void)
529 {
530         printk(banner);
531         return platform_driver_register(&s3c2410wdt_driver);
532 }
533
534 static void __exit watchdog_exit(void)
535 {
536         platform_driver_unregister(&s3c2410wdt_driver);
537 }
538
539 module_init(watchdog_init);
540 module_exit(watchdog_exit);
541
542 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
543               "Dimitry Andric <dimitry.andric@tomtom.com>");
544 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
545 MODULE_LICENSE("GPL");
546 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
547 MODULE_ALIAS("platform:s3c2410-wdt");