aboutsummaryrefslogtreecommitdiff
path: root/drivers/watchdog/bfin_wdt.c
blob: aa4d2e8a8ef93fcd4f26317c27f81352f00dfe13 (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
/*
 * Blackfin On-Chip Watchdog Driver
 *
 * Originally based on softdog.c
 * Copyright 2006-2010 Analog Devices Inc.
 * Copyright 2006-2007 Michele d'Amico
 * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <asm/blackfin.h>
#include <asm/bfin_watchdog.h>

#define stamp(fmt, args...) \
	pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
#define stampit() stamp("here i am")

#define WATCHDOG_NAME "bfin-wdt"

/* The BF561 has two watchdogs (one per core), but since Linux
 * only runs on core A, we'll just work with that one.
 */
#ifdef BF561_FAMILY
# define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
# define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
# define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
# define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
# define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
# define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
#endif

/* some defaults */
#define WATCHDOG_TIMEOUT 20

static unsigned int timeout = WATCHDOG_TIMEOUT;
static bool nowayout = WATCHDOG_NOWAYOUT;
static const struct watchdog_info bfin_wdt_info;
static unsigned long open_check;
static char expect_close;
static DEFINE_SPINLOCK(bfin_wdt_spinlock);

/**
 *	bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
 *
 *	The Userspace watchdog got a KeepAlive: schedule the next timeout.
 */
static int bfin_wdt_keepalive(void)
{
	stampit();
	bfin_write_WDOG_STAT(0);
	return 0;
}

/**
 *	bfin_wdt_stop - Stop the Watchdog
 *
 *	Stops the on-chip watchdog.
 */
static int bfin_wdt_stop(void)
{
	stampit();
	bfin_write_WDOG_CTL(WDEN_DISABLE);
	return 0;
}

/**
 *	bfin_wdt_start - Start the Watchdog
 *
 *	Starts the on-chip watchdog.  Automatically loads WDOG_CNT
 *	into WDOG_STAT for us.
 */
static int bfin_wdt_start(void)
{
	stampit();
	bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
	return 0;
}

/**
 *	bfin_wdt_running - Check Watchdog status
 *
 *	See if the watchdog is running.
 */
static int bfin_wdt_running(void)
{
	stampit();
	return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
}

/**
 *	bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
 *	@t: new timeout value (in seconds)
 *
 *	Translate the specified timeout in seconds into System Clock
 *	terms which is what the on-chip Watchdog requires.
 */
static int bfin_wdt_set_timeout(unsigned long t)
{
	u32 cnt, max_t, sclk;
	unsigned long flags;

	sclk = get_sclk();
	max_t = -1 / sclk;
	cnt = t * sclk;
	stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt);

	if (t > max_t) {
		pr_warn("timeout value is too large\n");
		return -EINVAL;
	}

	spin_lock_irqsave(&bfin_wdt_spinlock, flags);
	{
		int run = bfin_wdt_running();
		bfin_wdt_stop();
		bfin_write_WDOG_CNT(cnt);
		if (run)
			bfin_wdt_start();
	}
	spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);

	timeout = t;

	return 0;
}

/**
 *	bfin_wdt_open - Open the Device
 *	@inode: inode of device
 *	@file: file handle of device
 *
 *	Watchdog device is opened and started.
 */
static int bfin_wdt_open(struct inode *inode, struct file *file)
{
	stampit();

	if (test_and_set_bit(0, &open_check))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);

	bfin_wdt_keepalive();
	bfin_wdt_start();

	return nonseekable_open(inode, file);
}

/**
 *	bfin_wdt_close - Close the Device
 *	@inode: inode of device
 *	@file: file handle of device
 *
 *	Watchdog device is closed and stopped.
 */
static int bfin_wdt_release(struct inode *inode, struct file *file)
{
	stampit();

	if (expect_close == 42)
		bfin_wdt_stop();
	else {
		pr_crit("Unexpected close, not stopping watchdog!\n");
		bfin_wdt_keepalive();
	}
	expect_close = 0;
	clear_bit(0, &open_check);
	return 0;
}

/**
 *	bfin_wdt_write - Write to Device
 *	@file: file handle of device
 *	@buf: buffer to write
 *	@count: length of buffer
 *	@ppos: offset
 *
 *	Pings the watchdog on write.
 */
static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
						size_t len, loff_t *ppos)
{
	stampit();

	if (len) {
		if (!nowayout) {
			size_t i;

			/* In case it was set long ago */
			expect_close = 0;

			for (i = 0; i != len; i++) {
				char c;
				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		bfin_wdt_keepalive();
	}

	return len;
}

/**
 *	bfin_wdt_ioctl - Query Device
 *	@file: file handle of device
 *	@cmd: watchdog command
 *	@arg: argument
 *
 *	Query basic information from the device or ping it, as outlined by the
 *	watchdog API.
 */
static long bfin_wdt_ioctl(struct file *file,
				unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;

	stampit();

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
			return -EFAULT;
		else
			return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
	case WDIOC_SETOPTIONS: {
		unsigned long flags;
		int options, ret = -EINVAL;

		if (get_user(options, p))
			return -EFAULT;

		spin_lock_irqsave(&bfin_wdt_spinlock, flags);
		if (options & WDIOS_DISABLECARD) {
			bfin_wdt_stop();
			ret = 0;
		}
		if (options & WDIOS_ENABLECARD) {
			bfin_wdt_start();
			ret = 0;
		}
		spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
		return ret;
	}
	case WDIOC_KEEPALIVE:
		bfin_wdt_keepalive();
		return 0;
	case WDIOC_SETTIMEOUT: {
		int new_timeout;

		if (get_user(new_timeout, p))
			return -EFAULT;
		if (bfin_wdt_set_timeout(new_timeout))
			return -EINVAL;
	}
	/* Fall */
	case WDIOC_GETTIMEOUT:
		return put_user(timeout, p);
	default:
		return -ENOTTY;
	}
}

#ifdef CONFIG_PM
static int state_before_suspend;

/**
 *	bfin_wdt_suspend - suspend the watchdog
 *	@pdev: device being suspended
 *	@state: requested suspend state
 *
 *	Remember if the watchdog was running and stop it.
 *	TODO: is this even right?  Doesn't seem to be any
 *	      standard in the watchdog world ...
 */
static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
	stampit();

	state_before_suspend = bfin_wdt_running();
	bfin_wdt_stop();

	return 0;
}

/**
 *	bfin_wdt_resume - resume the watchdog
 *	@pdev: device being resumed
 *
 *	If the watchdog was running, turn it back on.
 */
static int bfin_wdt_resume(struct platform_device *pdev)
{
	stampit();

	if (state_before_suspend) {
		bfin_wdt_set_timeout(timeout);
		bfin_wdt_start();
	}

	return 0;
}
#else
# define bfin_wdt_suspend NULL
# define bfin_wdt_resume NULL
#endif

static const struct file_operations bfin_wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= bfin_wdt_write,
	.unlocked_ioctl	= bfin_wdt_ioctl,
	.open		= bfin_wdt_open,
	.release	= bfin_wdt_release,
};

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

static const struct watchdog_info bfin_wdt_info = {
	.identity = "Blackfin Watchdog",
	.options  = WDIOF_SETTIMEOUT |
		    WDIOF_KEEPALIVEPING |
		    WDIOF_MAGICCLOSE,
};

/**
 *	bfin_wdt_probe - Initialize module
 *
 *	Registers the misc device.  Actual device
 *	initialization is handled by bfin_wdt_open().
 */
static int bfin_wdt_probe(struct platform_device *pdev)
{
	int ret;

	ret = misc_register(&bfin_wdt_miscdev);
	if (ret) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
		       WATCHDOG_MINOR, ret);
		return ret;
	}

	pr_info("initialized: timeout=%d sec (nowayout=%d)\n",
		timeout, nowayout);

	return 0;
}

/**
 *	bfin_wdt_remove - Initialize module
 *
 *	Unregisters the misc device.  Actual device
 *	deinitialization is handled by bfin_wdt_close().
 */
static int bfin_wdt_remove(struct platform_device *pdev)
{
	misc_deregister(&bfin_wdt_miscdev);
	return 0;
}

/**
 *	bfin_wdt_shutdown - Soft Shutdown Handler
 *
 *	Handles the soft shutdown event.
 */
static void bfin_wdt_shutdown(struct platform_device *pdev)
{
	stampit();

	bfin_wdt_stop();
}

static struct platform_device *bfin_wdt_device;

static struct platform_driver bfin_wdt_driver = {
	.probe     = bfin_wdt_probe,
	.remove    = bfin_wdt_remove,
	.shutdown  = bfin_wdt_shutdown,
	.suspend   = bfin_wdt_suspend,
	.resume    = bfin_wdt_resume,
	.driver    = {
		.name  = WATCHDOG_NAME,
	},
};

/**
 *	bfin_wdt_init - Initialize module
 *
 *	Checks the module params and registers the platform device & driver.
 *	Real work is in the platform probe function.
 */
static int __init bfin_wdt_init(void)
{
	int ret;

	stampit();

	/* Check that the timeout value is within range */
	if (bfin_wdt_set_timeout(timeout))
		return -EINVAL;

	/* Since this is an on-chip device and needs no board-specific
	 * resources, we'll handle all the platform device stuff here.
	 */
	ret = platform_driver_register(&bfin_wdt_driver);
	if (ret) {
		pr_err("unable to register driver\n");
		return ret;
	}

	bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
								-1, NULL, 0);
	if (IS_ERR(bfin_wdt_device)) {
		pr_err("unable to register device\n");
		platform_driver_unregister(&bfin_wdt_driver);
		return PTR_ERR(bfin_wdt_device);
	}

	return 0;
}

/**
 *	bfin_wdt_exit - Deinitialize module
 *
 *	Back out the platform device & driver steps.  Real work is in the
 *	platform remove function.
 */
static void __exit bfin_wdt_exit(void)
{
	platform_device_unregister(bfin_wdt_device);
	platform_driver_unregister(&bfin_wdt_driver);
}

module_init(bfin_wdt_init);
module_exit(bfin_wdt_exit);

MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
MODULE_LICENSE("GPL");

module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout,
	"Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
		__MODULE_STRING(WATCHDOG_TIMEOUT) ")");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
	"Watchdog cannot be stopped once started (default="
		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");