summaryrefslogtreecommitdiff
path: root/drivers/char/watchdog/s3c2410_wdt.c
blob: 1699d2c28ce5edcd05d0ae6368ea06c22a8f2ec3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
/* linux/drivers/char/watchdog/s3c2410_wdt.c
 *
 * Copyright (c) 2004 Simtec Electronics
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * S3C2410 Watchdog Timer Support
 *
 * Based on, softdog.c by Alan Cox,
 *     (c) Copyright 1996 Alan Cox <alan@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Changelog:
 *	05-Oct-2004	BJD	Added semaphore init to stop crashes on open
 *				Fixed tmr_count / wdt_count confusion
 *				Added configurable debug
 *
 *	11-Jan-2004	BJD	Fixed divide-by-2 in timeout code
 *
 *	10-Mar-2005	LCVR	Changed S3C2410_VA to S3C24XX_VA
*/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/config.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/interrupt.h>

#include <asm/uaccess.h>
#include <asm/io.h>

#include <asm/arch/map.h>
#include <asm/hardware/clock.h>

#undef S3C24XX_VA_WATCHDOG
#define S3C24XX_VA_WATCHDOG (0)

#include <asm/arch/regs-watchdog.h>

#define PFX "s3c2410-wdt: "

#define CONFIG_S3C2410_WATCHDOG_ATBOOT		(0)
#define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME	(15)

#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
#else
static int nowayout = 0;
#endif

static int tmr_margin	= CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
static int tmr_atboot	= CONFIG_S3C2410_WATCHDOG_ATBOOT;
static int soft_noboot	= 0;
static int debug	= 0;

module_param(tmr_margin,  int, 0);
module_param(tmr_atboot,  int, 0);
module_param(nowayout,    int, 0);
module_param(soft_noboot, int, 0);
module_param(debug,	  int, 0);

MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");

MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));

MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");

MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");


typedef enum close_state {
	CLOSE_STATE_NOT,
	CLOSE_STATE_ALLOW=0x4021
} close_state_t;

static DECLARE_MUTEX(open_lock);

static struct resource	*wdt_mem;
static struct resource	*wdt_irq;
static struct clk	*wdt_clock;
static void __iomem	*wdt_base;
static unsigned int	 wdt_count;
static close_state_t	 allow_close;

/* watchdog control routines */

#define DBG(msg...) do { \
	if (debug) \
		printk(KERN_INFO msg); \
	} while(0)

/* functions */

static int s3c2410wdt_keepalive(void)
{
	writel(wdt_count, wdt_base + S3C2410_WTCNT);
	return 0;
}

static int s3c2410wdt_stop(void)
{
	unsigned long wtcon;

	wtcon = readl(wdt_base + S3C2410_WTCON);
	wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
	writel(wtcon, wdt_base + S3C2410_WTCON);

	return 0;
}

static int s3c2410wdt_start(void)
{
	unsigned long wtcon;

	s3c2410wdt_stop();

	wtcon = readl(wdt_base + S3C2410_WTCON);
	wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;

	if (soft_noboot) {
		wtcon |= S3C2410_WTCON_INTEN;
		wtcon &= ~S3C2410_WTCON_RSTEN;
	} else {
		wtcon &= ~S3C2410_WTCON_INTEN;
		wtcon |= S3C2410_WTCON_RSTEN;
	}

	DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
	    __FUNCTION__, wdt_count, wtcon);

	writel(wdt_count, wdt_base + S3C2410_WTDAT);
	writel(wdt_count, wdt_base + S3C2410_WTCNT);
	writel(wtcon, wdt_base + S3C2410_WTCON);

	return 0;
}

static int s3c2410wdt_set_heartbeat(int timeout)
{
	unsigned int freq = clk_get_rate(wdt_clock);
	unsigned int count;
	unsigned int divisor = 1;
	unsigned long wtcon;

	if (timeout < 1)
		return -EINVAL;

	freq /= 128;
	count = timeout * freq;

	DBG("%s: count=%d, timeout=%d, freq=%d\n",
	    __FUNCTION__, count, timeout, freq);

	/* if the count is bigger than the watchdog register,
	   then work out what we need to do (and if) we can
	   actually make this value
	*/

	if (count >= 0x10000) {
		for (divisor = 1; divisor <= 0x100; divisor++) {
			if ((count / divisor) < 0x10000)
				break;
		}

		if ((count / divisor) >= 0x10000) {
			printk(KERN_ERR PFX "timeout %d too big\n", timeout);
			return -EINVAL;
		}
	}

	tmr_margin = timeout;

	DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
	    __FUNCTION__, timeout, divisor, count, count/divisor);

	count /= divisor;
	wdt_count = count;

	/* update the pre-scaler */
	wtcon = readl(wdt_base + S3C2410_WTCON);
	wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
	wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);

	writel(count, wdt_base + S3C2410_WTDAT);
	writel(wtcon, wdt_base + S3C2410_WTCON);

	return 0;
}

/*
 *	/dev/watchdog handling
 */

static int s3c2410wdt_open(struct inode *inode, struct file *file)
{
	if(down_trylock(&open_lock))
		return -EBUSY;

	if (nowayout) {
		__module_get(THIS_MODULE);
	} else {
		allow_close = CLOSE_STATE_ALLOW;
	}

	/* start the timer */
	s3c2410wdt_start();
	return nonseekable_open(inode, file);
}

static int s3c2410wdt_release(struct inode *inode, struct file *file)
{
	/*
	 *	Shut off the timer.
	 * 	Lock it in if it's a module and we set nowayout
	 */
	if (allow_close == CLOSE_STATE_ALLOW) {
		s3c2410wdt_stop();
	} else {
		printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
		s3c2410wdt_keepalive();
	}

	allow_close = CLOSE_STATE_NOT;
	up(&open_lock);
	return 0;
}

static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
				size_t len, loff_t *ppos)
{
	/*
	 *	Refresh the timer.
	 */
	if(len) {
		if (!nowayout) {
			size_t i;

			/* In case it was set long ago */
			allow_close = CLOSE_STATE_NOT;

			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					allow_close = CLOSE_STATE_ALLOW;
			}
		}

		s3c2410wdt_keepalive();
	}
	return len;
}

#define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE

static struct watchdog_info s3c2410_wdt_ident = {
	.options          =     OPTIONS,
	.firmware_version =	0,
	.identity         =	"S3C2410 Watchdog",
};


static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
	unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int new_margin;

	switch (cmd) {
		default:
			return -ENOIOCTLCMD;

		case WDIOC_GETSUPPORT:
			return copy_to_user(argp, &s3c2410_wdt_ident,
				sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;

		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0, p);

		case WDIOC_KEEPALIVE:
			s3c2410wdt_keepalive();
			return 0;

		case WDIOC_SETTIMEOUT:
			if (get_user(new_margin, p))
				return -EFAULT;

			if (s3c2410wdt_set_heartbeat(new_margin))
				return -EINVAL;

			s3c2410wdt_keepalive();
			return put_user(tmr_margin, p);

		case WDIOC_GETTIMEOUT:
			return put_user(tmr_margin, p);
	}
}

/*
 *	Notifier for system down
 */

static int s3c2410wdt_notify_sys(struct notifier_block *this, unsigned long code,
			      void *unused)
{
	if(code==SYS_DOWN || code==SYS_HALT) {
		/* Turn the WDT off */
		s3c2410wdt_stop();
	}
	return NOTIFY_DONE;
}

/* kernel interface */

static struct file_operations s3c2410wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= s3c2410wdt_write,
	.ioctl		= s3c2410wdt_ioctl,
	.open		= s3c2410wdt_open,
	.release	= s3c2410wdt_release,
};

static struct miscdevice s3c2410wdt_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &s3c2410wdt_fops,
};

static struct notifier_block s3c2410wdt_notifier = {
	.notifier_call	= s3c2410wdt_notify_sys,
};

/* interrupt handler code */

static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
				  struct pt_regs *regs)
{
	printk(KERN_INFO PFX "Watchdog timer expired!\n");

	s3c2410wdt_keepalive();
	return IRQ_HANDLED;
}
/* device interface */

static int s3c2410wdt_probe(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct resource *res;
	int started = 0;
	int ret;
	int size;

	DBG("%s: probe=%p, device=%p\n", __FUNCTION__, pdev, dev);

	/* get the memory region for the watchdog timer */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		printk(KERN_INFO PFX "failed to get memory region resouce\n");
		return -ENOENT;
	}

	size = (res->end-res->start)+1;
	wdt_mem = request_mem_region(res->start, size, pdev->name);
	if (wdt_mem == NULL) {
		printk(KERN_INFO PFX "failed to get memory region\n");
		return -ENOENT;
	}

	wdt_base = ioremap(res->start, size);
	if (wdt_base == 0) {
		printk(KERN_INFO PFX "failed to ioremap() region\n");
		return -EINVAL;
	}

	DBG("probe: mapped wdt_base=%p\n", wdt_base);

	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (res == NULL) {
		printk(KERN_INFO PFX "failed to get irq resource\n");
		return -ENOENT;
	}

	ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, dev);
	if (ret != 0) {
		printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
		return ret;
	}

	wdt_clock = clk_get(dev, "watchdog");
	if (wdt_clock == NULL) {
		printk(KERN_INFO PFX "failed to find watchdog clock source\n");
		return -ENOENT;
	}

	clk_use(wdt_clock);
	clk_enable(wdt_clock);

	/* see if we can actually set the requested timer margin, and if
	 * not, try the default value */

	if (s3c2410wdt_set_heartbeat(tmr_margin)) {
		started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);

		if (started == 0) {
			printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
			       CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
		} else {
			printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
		}
	}

	ret = register_reboot_notifier(&s3c2410wdt_notifier);
	if (ret) {
		printk (KERN_ERR PFX "cannot register reboot notifier (%d)\n",
			ret);
		return ret;
	}

	ret = misc_register(&s3c2410wdt_miscdev);
	if (ret) {
		printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
			WATCHDOG_MINOR, ret);
		unregister_reboot_notifier(&s3c2410wdt_notifier);
		return ret;
	}

	if (tmr_atboot && started == 0) {
		printk(KERN_INFO PFX "Starting Watchdog Timer\n");
		s3c2410wdt_start();
	}

	return 0;
}

static int s3c2410wdt_remove(struct device *dev)
{
	if (wdt_mem != NULL) {
		release_resource(wdt_mem);
		kfree(wdt_mem);
		wdt_mem = NULL;
	}

	if (wdt_irq != NULL) {
		free_irq(wdt_irq->start, dev);
		wdt_irq = NULL;
	}

	if (wdt_clock != NULL) {
		clk_disable(wdt_clock);
		clk_unuse(wdt_clock);
		clk_put(wdt_clock);
		wdt_clock = NULL;
	}

	misc_deregister(&s3c2410wdt_miscdev);
	return 0;
}

static struct device_driver s3c2410wdt_driver = {
	.name		= "s3c2410-wdt",
	.bus		= &platform_bus_type,
	.probe		= s3c2410wdt_probe,
	.remove		= s3c2410wdt_remove,
};



static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";

static int __init watchdog_init(void)
{
	printk(banner);
	return driver_register(&s3c2410wdt_driver);
}

static void __exit watchdog_exit(void)
{
	driver_unregister(&s3c2410wdt_driver);
	unregister_reboot_notifier(&s3c2410wdt_notifier);
}

module_init(watchdog_init);
module_exit(watchdog_exit);

MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);