Free Electrons

Embedded Linux Experts

  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
/*
 *	Watchdog driver for the mpcore watchdog timer
 *
 *	(c) Copyright 2004 ARM Limited
 *
 *	Based on the SoftDog driver:
 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *						All Rights Reserved.
 *
 *	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.
 *
 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
 *	warranty for any of this software. This material is provided
 *	"AS-IS" and at no charge.
 *
 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <asm/smp_twd.h>

struct mpcore_wdt {
	unsigned long	timer_alive;
	struct device	*dev;
	void __iomem	*base;
	int		irq;
	unsigned int	perturb;
	char		expect_close;
};

static struct platform_device *mpcore_wdt_pdev;
static DEFINE_SPINLOCK(wdt_lock);

#define TIMER_MARGIN	60
static int mpcore_margin = TIMER_MARGIN;
module_param(mpcore_margin, int, 0);
MODULE_PARM_DESC(mpcore_margin,
	"MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
				__MODULE_STRING(TIMER_MARGIN) ")");

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

#define ONLY_TESTING	0
static int mpcore_noboot = ONLY_TESTING;
module_param(mpcore_noboot, int, 0);
MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
	"set to 1 to ignore reboots, 0 to reboot (default="
					__MODULE_STRING(ONLY_TESTING) ")");

/*
 *	This is the interrupt handler.  Note that we only use this
 *	in testing mode, so don't actually do a reboot here.
 */
static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
{
	struct mpcore_wdt *wdt = arg;

	/* Check it really was our interrupt */
	if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
		dev_printk(KERN_CRIT, wdt->dev,
					"Triggered - Reboot ignored.\n");
		/* Clear the interrupt on the watchdog */
		writel(1, wdt->base + TWD_WDOG_INTSTAT);
		return IRQ_HANDLED;
	}
	return IRQ_NONE;
}

/*
 *	mpcore_wdt_keepalive - reload the timer
 *
 *	Note that the spec says a DIFFERENT value must be written to the reload
 *	register each time.  The "perturb" variable deals with this by adding 1
 *	to the count every other time the function is called.
 */
static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
{
	unsigned long count;

	spin_lock(&wdt_lock);
	/* Assume prescale is set to 256 */
	count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
	count = (0xFFFFFFFFU - count) * (HZ / 5);
	count = (count / 256) * mpcore_margin;

	/* Reload the counter */
	writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
	wdt->perturb = wdt->perturb ? 0 : 1;
	spin_unlock(&wdt_lock);
}

static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
{
	spin_lock(&wdt_lock);
	writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
	writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
	writel(0x0, wdt->base + TWD_WDOG_CONTROL);
	spin_unlock(&wdt_lock);
}

static void mpcore_wdt_start(struct mpcore_wdt *wdt)
{
	dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");

	/* This loads the count register but does NOT start the count yet */
	mpcore_wdt_keepalive(wdt);

	if (mpcore_noboot) {
		/* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
		writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
	} else {
		/* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
		writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
	}
}

static int mpcore_wdt_set_heartbeat(int t)
{
	if (t < 0x0001 || t > 0xFFFF)
		return -EINVAL;

	mpcore_margin = t;
	return 0;
}

/*
 *	/dev/watchdog handling
 */
static int mpcore_wdt_open(struct inode *inode, struct file *file)
{
	struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_pdev);

	if (test_and_set_bit(0, &wdt->timer_alive))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);

	file->private_data = wdt;

	/*
	 *	Activate timer
	 */
	mpcore_wdt_start(wdt);

	return nonseekable_open(inode, file);
}

static int mpcore_wdt_release(struct inode *inode, struct file *file)
{
	struct mpcore_wdt *wdt = file->private_data;

	/*
	 *	Shut off the timer.
	 *	Lock it in if it's a module and we set nowayout
	 */
	if (wdt->expect_close == 42)
		mpcore_wdt_stop(wdt);
	else {
		dev_printk(KERN_CRIT, wdt->dev,
				"unexpected close, not stopping watchdog!\n");
		mpcore_wdt_keepalive(wdt);
	}
	clear_bit(0, &wdt->timer_alive);
	wdt->expect_close = 0;
	return 0;
}

static ssize_t mpcore_wdt_write(struct file *file, const char *data,
						size_t len, loff_t *ppos)
{
	struct mpcore_wdt *wdt = file->private_data;

	/*
	 *	Refresh the timer.
	 */
	if (len) {
		if (!nowayout) {
			size_t i;

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

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

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					wdt->expect_close = 42;
			}
		}
		mpcore_wdt_keepalive(wdt);
	}
	return len;
}

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

static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	struct mpcore_wdt *wdt = file->private_data;
	int ret;
	union {
		struct watchdog_info ident;
		int i;
	} uarg;

	if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
		return -ENOTTY;

	if (_IOC_DIR(cmd) & _IOC_WRITE) {
		ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
		if (ret)
			return -EFAULT;
	}

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		uarg.ident = ident;
		ret = 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		uarg.i = 0;
		ret = 0;
		break;

	case WDIOC_SETOPTIONS:
		ret = -EINVAL;
		if (uarg.i & WDIOS_DISABLECARD) {
			mpcore_wdt_stop(wdt);
			ret = 0;
		}
		if (uarg.i & WDIOS_ENABLECARD) {
			mpcore_wdt_start(wdt);
			ret = 0;
		}
		break;

	case WDIOC_KEEPALIVE:
		mpcore_wdt_keepalive(wdt);
		ret = 0;
		break;

	case WDIOC_SETTIMEOUT:
		ret = mpcore_wdt_set_heartbeat(uarg.i);
		if (ret)
			break;

		mpcore_wdt_keepalive(wdt);
		/* Fall */
	case WDIOC_GETTIMEOUT:
		uarg.i = mpcore_margin;
		ret = 0;
		break;

	default:
		return -ENOTTY;
	}

	if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
		ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
		if (ret)
			ret = -EFAULT;
	}
	return ret;
}

/*
 *	System shutdown handler.  Turn off the watchdog if we're
 *	restarting or halting the system.
 */
static void mpcore_wdt_shutdown(struct platform_device *pdev)
{
	struct mpcore_wdt *wdt = platform_get_drvdata(pdev);

	if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
		mpcore_wdt_stop(wdt);
}

/*
 *	Kernel Interfaces
 */
static const struct file_operations mpcore_wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= mpcore_wdt_write,
	.unlocked_ioctl	= mpcore_wdt_ioctl,
	.open		= mpcore_wdt_open,
	.release	= mpcore_wdt_release,
};

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

static int __devinit mpcore_wdt_probe(struct platform_device *pdev)
{
	struct mpcore_wdt *wdt;
	struct resource *res;
	int ret;

	/* We only accept one device, and it must have an id of -1 */
	if (pdev->id != -1)
		return -ENODEV;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENODEV;

	wdt = devm_kzalloc(&pdev->dev, sizeof(struct mpcore_wdt), GFP_KERNEL);
	if (!wdt)
		return -ENOMEM;

	wdt->dev = &pdev->dev;
	wdt->irq = platform_get_irq(pdev, 0);
	if (wdt->irq >= 0) {
		ret = devm_request_irq(wdt->dev, wdt->irq, mpcore_wdt_fire, 0,
				"mpcore_wdt", wdt);
		if (ret) {
			dev_printk(KERN_ERR, wdt->dev,
					"cannot register IRQ%d for watchdog\n",
					wdt->irq);
			return ret;
		}
	}

	wdt->base = devm_ioremap(wdt->dev, res->start, resource_size(res));
	if (!wdt->base)
		return -ENOMEM;

	mpcore_wdt_miscdev.parent = &pdev->dev;
	ret = misc_register(&mpcore_wdt_miscdev);
	if (ret) {
		dev_printk(KERN_ERR, wdt->dev,
			"cannot register miscdev on minor=%d (err=%d)\n",
							WATCHDOG_MINOR, ret);
		return ret;
	}

	mpcore_wdt_stop(wdt);
	platform_set_drvdata(pdev, wdt);
	mpcore_wdt_pdev = pdev;

	return 0;
}

static int __devexit mpcore_wdt_remove(struct platform_device *pdev)
{
	platform_set_drvdata(pdev, NULL);

	misc_deregister(&mpcore_wdt_miscdev);

	mpcore_wdt_pdev = NULL;

	return 0;
}

#ifdef CONFIG_PM
static int mpcore_wdt_suspend(struct platform_device *pdev, pm_message_t msg)
{
	struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
	mpcore_wdt_stop(wdt);		/* Turn the WDT off */
	return 0;
}

static int mpcore_wdt_resume(struct platform_device *pdev)
{
	struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
	/* re-activate timer */
	if (test_bit(0, &wdt->timer_alive))
		mpcore_wdt_start(wdt);
	return 0;
}
#else
#define mpcore_wdt_suspend	NULL
#define mpcore_wdt_resume	NULL
#endif

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:mpcore_wdt");

static struct platform_driver mpcore_wdt_driver = {
	.probe		= mpcore_wdt_probe,
	.remove		= __devexit_p(mpcore_wdt_remove),
	.suspend	= mpcore_wdt_suspend,
	.resume		= mpcore_wdt_resume,
	.shutdown	= mpcore_wdt_shutdown,
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "mpcore_wdt",
	},
};

static int __init mpcore_wdt_init(void)
{
	/*
	 * Check that the margin value is within it's range;
	 * if not reset to the default
	 */
	if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
		mpcore_wdt_set_heartbeat(TIMER_MARGIN);
		pr_info("mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
			TIMER_MARGIN);
	}

	pr_info("MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n",
		mpcore_noboot, mpcore_margin, nowayout);

	return platform_driver_register(&mpcore_wdt_driver);
}

static void __exit mpcore_wdt_exit(void)
{
	platform_driver_unregister(&mpcore_wdt_driver);
}

module_init(mpcore_wdt_init);
module_exit(mpcore_wdt_exit);

MODULE_AUTHOR("ARM Limited");
MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);