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On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:
[mmotm.git] / drivers / watchdog / s3c2410_wdt.c
blobb57ac6b49147400a0230a777b81592202947a439
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");
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