e31925ee83462774ff573d4d4ae1d8d2ff538858
[linux-2.6.git] / 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, 0 to reboot (default depends on ONLY_TESTING)");
72 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
73
74
75 typedef enum close_state {
76         CLOSE_STATE_NOT,
77         CLOSE_STATE_ALLOW = 0x4021
78 } close_state_t;
79
80 static unsigned long open_lock;
81 static struct device    *wdt_dev;       /* platform device attached to */
82 static struct resource  *wdt_mem;
83 static struct resource  *wdt_irq;
84 static struct clk       *wdt_clock;
85 static void __iomem     *wdt_base;
86 static unsigned int      wdt_count;
87 static close_state_t     allow_close;
88 static DEFINE_SPINLOCK(wdt_lock);
89
90 /* watchdog control routines */
91
92 #define DBG(msg...) do { \
93         if (debug) \
94                 printk(KERN_INFO msg); \
95         } while (0)
96
97 /* functions */
98
99 static void s3c2410wdt_keepalive(void)
100 {
101         spin_lock(&wdt_lock);
102         writel(wdt_count, wdt_base + S3C2410_WTCNT);
103         spin_unlock(&wdt_lock);
104 }
105
106 static void __s3c2410wdt_stop(void)
107 {
108         unsigned long wtcon;
109
110         wtcon = readl(wdt_base + S3C2410_WTCON);
111         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
112         writel(wtcon, wdt_base + S3C2410_WTCON);
113 }
114
115 static void s3c2410wdt_stop(void)
116 {
117         spin_lock(&wdt_lock);
118         __s3c2410wdt_stop();
119         spin_unlock(&wdt_lock);
120 }
121
122 static void s3c2410wdt_start(void)
123 {
124         unsigned long wtcon;
125
126         spin_lock(&wdt_lock);
127
128         __s3c2410wdt_stop();
129
130         wtcon = readl(wdt_base + S3C2410_WTCON);
131         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
132
133         if (soft_noboot) {
134                 wtcon |= S3C2410_WTCON_INTEN;
135                 wtcon &= ~S3C2410_WTCON_RSTEN;
136         } else {
137                 wtcon &= ~S3C2410_WTCON_INTEN;
138                 wtcon |= S3C2410_WTCON_RSTEN;
139         }
140
141         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
142             __func__, wdt_count, wtcon);
143
144         writel(wdt_count, wdt_base + S3C2410_WTDAT);
145         writel(wdt_count, wdt_base + S3C2410_WTCNT);
146         writel(wtcon, wdt_base + S3C2410_WTCON);
147         spin_unlock(&wdt_lock);
148 }
149
150 static int s3c2410wdt_set_heartbeat(int timeout)
151 {
152         unsigned int freq = clk_get_rate(wdt_clock);
153         unsigned int count;
154         unsigned int divisor = 1;
155         unsigned long wtcon;
156
157         if (timeout < 1)
158                 return -EINVAL;
159
160         freq /= 128;
161         count = timeout * freq;
162
163         DBG("%s: count=%d, timeout=%d, freq=%d\n",
164             __func__, count, timeout, freq);
165
166         /* if the count is bigger than the watchdog register,
167            then work out what we need to do (and if) we can
168            actually make this value
169         */
170
171         if (count >= 0x10000) {
172                 for (divisor = 1; divisor <= 0x100; divisor++) {
173                         if ((count / divisor) < 0x10000)
174                                 break;
175                 }
176
177                 if ((count / divisor) >= 0x10000) {
178                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
179                         return -EINVAL;
180                 }
181         }
182
183         tmr_margin = timeout;
184
185         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
186             __func__, timeout, divisor, count, count/divisor);
187
188         count /= divisor;
189         wdt_count = count;
190
191         /* update the pre-scaler */
192         wtcon = readl(wdt_base + S3C2410_WTCON);
193         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
194         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
195
196         writel(count, wdt_base + S3C2410_WTDAT);
197         writel(wtcon, wdt_base + S3C2410_WTCON);
198
199         return 0;
200 }
201
202 /*
203  *      /dev/watchdog handling
204  */
205
206 static int s3c2410wdt_open(struct inode *inode, struct file *file)
207 {
208         if (test_and_set_bit(0, &open_lock))
209                 return -EBUSY;
210
211         if (nowayout)
212                 __module_get(THIS_MODULE);
213
214         allow_close = CLOSE_STATE_NOT;
215
216         /* start the timer */
217         s3c2410wdt_start();
218         return nonseekable_open(inode, file);
219 }
220
221 static int s3c2410wdt_release(struct inode *inode, struct file *file)
222 {
223         /*
224          *      Shut off the timer.
225          *      Lock it in if it's a module and we set nowayout
226          */
227
228         if (allow_close == CLOSE_STATE_ALLOW)
229                 s3c2410wdt_stop();
230         else {
231                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
232                 s3c2410wdt_keepalive();
233         }
234         allow_close = CLOSE_STATE_NOT;
235         clear_bit(0, &open_lock);
236         return 0;
237 }
238
239 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
240                                 size_t len, loff_t *ppos)
241 {
242         /*
243          *      Refresh the timer.
244          */
245         if (len) {
246                 if (!nowayout) {
247                         size_t i;
248
249                         /* In case it was set long ago */
250                         allow_close = CLOSE_STATE_NOT;
251
252                         for (i = 0; i != len; i++) {
253                                 char c;
254
255                                 if (get_user(c, data + i))
256                                         return -EFAULT;
257                                 if (c == 'V')
258                                         allow_close = CLOSE_STATE_ALLOW;
259                         }
260                 }
261                 s3c2410wdt_keepalive();
262         }
263         return len;
264 }
265
266 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
267
268 static const struct watchdog_info s3c2410_wdt_ident = {
269         .options          =     OPTIONS,
270         .firmware_version =     0,
271         .identity         =     "S3C2410 Watchdog",
272 };
273
274
275 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
276                                                         unsigned long arg)
277 {
278         void __user *argp = (void __user *)arg;
279         int __user *p = argp;
280         int new_margin;
281
282         switch (cmd) {
283         case WDIOC_GETSUPPORT:
284                 return copy_to_user(argp, &s3c2410_wdt_ident,
285                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
286         case WDIOC_GETSTATUS:
287         case WDIOC_GETBOOTSTATUS:
288                 return put_user(0, p);
289         case WDIOC_KEEPALIVE:
290                 s3c2410wdt_keepalive();
291                 return 0;
292         case WDIOC_SETTIMEOUT:
293                 if (get_user(new_margin, p))
294                         return -EFAULT;
295                 if (s3c2410wdt_set_heartbeat(new_margin))
296                         return -EINVAL;
297                 s3c2410wdt_keepalive();
298                 return put_user(tmr_margin, p);
299         case WDIOC_GETTIMEOUT:
300                 return put_user(tmr_margin, p);
301         default:
302                 return -ENOTTY;
303         }
304 }
305
306 /* kernel interface */
307
308 static const struct file_operations s3c2410wdt_fops = {
309         .owner          = THIS_MODULE,
310         .llseek         = no_llseek,
311         .write          = s3c2410wdt_write,
312         .unlocked_ioctl = s3c2410wdt_ioctl,
313         .open           = s3c2410wdt_open,
314         .release        = s3c2410wdt_release,
315 };
316
317 static struct miscdevice s3c2410wdt_miscdev = {
318         .minor          = WATCHDOG_MINOR,
319         .name           = "watchdog",
320         .fops           = &s3c2410wdt_fops,
321 };
322
323 /* interrupt handler code */
324
325 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
326 {
327         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
328
329         s3c2410wdt_keepalive();
330         return IRQ_HANDLED;
331 }
332 /* device interface */
333
334 static int s3c2410wdt_probe(struct platform_device *pdev)
335 {
336         struct resource *res;
337         struct device *dev;
338         unsigned int wtcon;
339         int started = 0;
340         int ret;
341         int size;
342
343         DBG("%s: probe=%p\n", __func__, pdev);
344
345         dev = &pdev->dev;
346         wdt_dev = &pdev->dev;
347
348         /* get the memory region for the watchdog timer */
349
350         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
351         if (res == NULL) {
352                 dev_err(dev, "no memory resource specified\n");
353                 return -ENOENT;
354         }
355
356         size = (res->end - res->start) + 1;
357         wdt_mem = request_mem_region(res->start, size, pdev->name);
358         if (wdt_mem == NULL) {
359                 dev_err(dev, "failed to get memory region\n");
360                 ret = -ENOENT;
361                 goto err_req;
362         }
363
364         wdt_base = ioremap(res->start, size);
365         if (wdt_base == NULL) {
366                 dev_err(dev, "failed to ioremap() region\n");
367                 ret = -EINVAL;
368                 goto err_req;
369         }
370
371         DBG("probe: mapped wdt_base=%p\n", wdt_base);
372
373         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
374         if (wdt_irq == NULL) {
375                 dev_err(dev, "no irq resource specified\n");
376                 ret = -ENOENT;
377                 goto err_map;
378         }
379
380         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
381         if (ret != 0) {
382                 dev_err(dev, "failed to install irq (%d)\n", ret);
383                 goto err_map;
384         }
385
386         wdt_clock = clk_get(&pdev->dev, "watchdog");
387         if (IS_ERR(wdt_clock)) {
388                 dev_err(dev, "failed to find watchdog clock source\n");
389                 ret = PTR_ERR(wdt_clock);
390                 goto err_irq;
391         }
392
393         clk_enable(wdt_clock);
394
395         /* see if we can actually set the requested timer margin, and if
396          * not, try the default value */
397
398         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
399                 started = s3c2410wdt_set_heartbeat(
400                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
401
402                 if (started == 0)
403                         dev_info(dev,
404                            "tmr_margin value out of range, default %d used\n",
405                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
406                 else
407                         dev_info(dev, "default timer value is out of range, cannot start\n");
408         }
409
410         ret = misc_register(&s3c2410wdt_miscdev);
411         if (ret) {
412                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
413                         WATCHDOG_MINOR, ret);
414                 goto err_clk;
415         }
416
417         if (tmr_atboot && started == 0) {
418                 dev_info(dev, "starting watchdog timer\n");
419                 s3c2410wdt_start();
420         } else if (!tmr_atboot) {
421                 /* if we're not enabling the watchdog, then ensure it is
422                  * disabled if it has been left running from the bootloader
423                  * or other source */
424
425                 s3c2410wdt_stop();
426         }
427
428         /* print out a statement of readiness */
429
430         wtcon = readl(wdt_base + S3C2410_WTCON);
431
432         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
433                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
434                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
435                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
436
437         return 0;
438
439  err_clk:
440         clk_disable(wdt_clock);
441         clk_put(wdt_clock);
442
443  err_irq:
444         free_irq(wdt_irq->start, pdev);
445
446  err_map:
447         iounmap(wdt_base);
448
449  err_req:
450         release_resource(wdt_mem);
451         kfree(wdt_mem);
452
453         return ret;
454 }
455
456 static int s3c2410wdt_remove(struct platform_device *dev)
457 {
458         release_resource(wdt_mem);
459         kfree(wdt_mem);
460         wdt_mem = NULL;
461
462         free_irq(wdt_irq->start, dev);
463         wdt_irq = NULL;
464
465         clk_disable(wdt_clock);
466         clk_put(wdt_clock);
467         wdt_clock = NULL;
468
469         iounmap(wdt_base);
470         misc_deregister(&s3c2410wdt_miscdev);
471         return 0;
472 }
473
474 static void s3c2410wdt_shutdown(struct platform_device *dev)
475 {
476         s3c2410wdt_stop();
477 }
478
479 #ifdef CONFIG_PM
480
481 static unsigned long wtcon_save;
482 static unsigned long wtdat_save;
483
484 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
485 {
486         /* Save watchdog state, and turn it off. */
487         wtcon_save = readl(wdt_base + S3C2410_WTCON);
488         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
489
490         /* Note that WTCNT doesn't need to be saved. */
491         s3c2410wdt_stop();
492
493         return 0;
494 }
495
496 static int s3c2410wdt_resume(struct platform_device *dev)
497 {
498         /* Restore watchdog state. */
499
500         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
501         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
502         writel(wtcon_save, wdt_base + S3C2410_WTCON);
503
504         printk(KERN_INFO PFX "watchdog %sabled\n",
505                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
506
507         return 0;
508 }
509
510 #else
511 #define s3c2410wdt_suspend NULL
512 #define s3c2410wdt_resume  NULL
513 #endif /* CONFIG_PM */
514
515
516 static struct platform_driver s3c2410wdt_driver = {
517         .probe          = s3c2410wdt_probe,
518         .remove         = s3c2410wdt_remove,
519         .shutdown       = s3c2410wdt_shutdown,
520         .suspend        = s3c2410wdt_suspend,
521         .resume         = s3c2410wdt_resume,
522         .driver         = {
523                 .owner  = THIS_MODULE,
524                 .name   = "s3c2410-wdt",
525         },
526 };
527
528
529 static char banner[] __initdata =
530         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
531
532 static int __init watchdog_init(void)
533 {
534         printk(banner);
535         return platform_driver_register(&s3c2410wdt_driver);
536 }
537
538 static void __exit watchdog_exit(void)
539 {
540         platform_driver_unregister(&s3c2410wdt_driver);
541 }
542
543 module_init(watchdog_init);
544 module_exit(watchdog_exit);
545
546 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
547               "Dimitry Andric <dimitry.andric@tomtom.com>");
548 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
549 MODULE_LICENSE("GPL");
550 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
551 MODULE_ALIAS("platform:s3c2410-wdt");