xref: /openbmc/linux/drivers/watchdog/ts72xx_wdt.c (revision f538ed9e) 
1 /*
2  * Watchdog driver for Technologic Systems TS-72xx based SBCs
3  * (TS-7200, TS-7250 and TS-7260). These boards have external
4  * glue logic CPLD chip, which includes programmable watchdog
5  * timer.
6  *
7  * Copyright (c) 2009 Mika Westerberg <mika.westerberg@iki.fi>
8  *
9  * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
10  *
11  * This file is licensed under the terms of the GNU General Public
12  * License version 2. This program is licensed "as is" without any
13  * warranty of any kind, whether express or implied.
14  */
15 
16 #include <linux/fs.h>
17 #include <linux/io.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/miscdevice.h>
21 #include <linux/mutex.h>
22 #include <linux/platform_device.h>
23 #include <linux/watchdog.h>
24 #include <linux/uaccess.h>
25 
26 #define TS72XX_WDT_FEED_VAL		0x05
27 #define TS72XX_WDT_DEFAULT_TIMEOUT	8
28 
29 static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
30 module_param(timeout, int, 0);
31 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
32 			  "(1 <= timeout <= 8, default="
33 			  __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
34 			  ")");
35 
36 static int nowayout = WATCHDOG_NOWAYOUT;
37 module_param(nowayout, int, 0);
38 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
39 
40 /**
41  * struct ts72xx_wdt - watchdog control structure
42  * @lock: lock that protects this structure
43  * @regval: watchdog timeout value suitable for control register
44  * @flags: flags controlling watchdog device state
45  * @control_reg: watchdog control register
46  * @feed_reg: watchdog feed register
47  * @pdev: back pointer to platform dev
48  */
49 struct ts72xx_wdt {
50 	struct mutex	lock;
51 	int		regval;
52 
53 #define TS72XX_WDT_BUSY_FLAG		1
54 #define TS72XX_WDT_EXPECT_CLOSE_FLAG	2
55 	int		flags;
56 
57 	void __iomem	*control_reg;
58 	void __iomem	*feed_reg;
59 
60 	struct platform_device *pdev;
61 };
62 
63 struct platform_device *ts72xx_wdt_pdev;
64 
65 /*
66  * TS-72xx Watchdog supports following timeouts (value written
67  * to control register):
68  *	value	description
69  *	-------------------------
70  * 	0x00	watchdog disabled
71  *	0x01	250ms
72  *	0x02	500ms
73  *	0x03	1s
74  *	0x04	reserved
75  *	0x05	2s
76  *	0x06	4s
77  *	0x07	8s
78  *
79  * Timeouts below 1s are not very usable so we don't
80  * allow them at all.
81  *
82  * We provide two functions that convert between these:
83  * timeout_to_regval() and regval_to_timeout().
84  */
85 static const struct {
86 	int	timeout;
87 	int	regval;
88 } ts72xx_wdt_map[] = {
89 	{ 1, 3 },
90 	{ 2, 5 },
91 	{ 4, 6 },
92 	{ 8, 7 },
93 };
94 
95 /**
96  * timeout_to_regval() - converts given timeout to control register value
97  * @new_timeout: timeout in seconds to be converted
98  *
99  * Function converts given @new_timeout into valid value that can
100  * be programmed into watchdog control register. When conversion is
101  * not possible, function returns %-EINVAL.
102  */
103 static int timeout_to_regval(int new_timeout)
104 {
105 	int i;
106 
107 	/* first limit it to 1 - 8 seconds */
108 	new_timeout = clamp_val(new_timeout, 1, 8);
109 
110 	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
111 		if (ts72xx_wdt_map[i].timeout >= new_timeout)
112 			return ts72xx_wdt_map[i].regval;
113 	}
114 
115 	return -EINVAL;
116 }
117 
118 /**
119  * regval_to_timeout() - converts control register value to timeout
120  * @regval: control register value to be converted
121  *
122  * Function converts given @regval to timeout in seconds (1, 2, 4 or 8).
123  * If @regval cannot be converted, function returns %-EINVAL.
124  */
125 static int regval_to_timeout(int regval)
126 {
127 	int i;
128 
129 	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
130 		if (ts72xx_wdt_map[i].regval == regval)
131 			return ts72xx_wdt_map[i].timeout;
132 	}
133 
134 	return -EINVAL;
135 }
136 
137 /**
138  * ts72xx_wdt_kick() - kick the watchdog
139  * @wdt: watchdog to be kicked
140  *
141  * Called with @wdt->lock held.
142  */
143 static inline void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
144 {
145 	__raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
146 }
147 
148 /**
149  * ts72xx_wdt_start() - starts the watchdog timer
150  * @wdt: watchdog to be started
151  *
152  * This function programs timeout to watchdog timer
153  * and starts it.
154  *
155  * Called with @wdt->lock held.
156  */
157 static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
158 {
159 	/*
160 	 * To program the wdt, it first must be "fed" and
161 	 * only after that (within 30 usecs) the configuration
162 	 * can be changed.
163 	 */
164 	ts72xx_wdt_kick(wdt);
165 	__raw_writeb((u8)wdt->regval, wdt->control_reg);
166 }
167 
168 /**
169  * ts72xx_wdt_stop() - stops the watchdog timer
170  * @wdt: watchdog to be stopped
171  *
172  * Called with @wdt->lock held.
173  */
174 static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
175 {
176 	ts72xx_wdt_kick(wdt);
177 	__raw_writeb(0, wdt->control_reg);
178 }
179 
180 static int ts72xx_wdt_open(struct inode *inode, struct file *file)
181 {
182 	struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
183 	int regval;
184 
185 	/*
186 	 * Try to convert default timeout to valid register
187 	 * value first.
188 	 */
189 	regval = timeout_to_regval(timeout);
190 	if (regval < 0) {
191 		dev_err(&wdt->pdev->dev,
192 			"failed to convert timeout (%d) to register value\n",
193 			timeout);
194 		return -EINVAL;
195 	}
196 
197 	if (mutex_lock_interruptible(&wdt->lock))
198 		return -ERESTARTSYS;
199 
200 	if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
201 		mutex_unlock(&wdt->lock);
202 		return -EBUSY;
203 	}
204 
205 	wdt->flags = TS72XX_WDT_BUSY_FLAG;
206 	wdt->regval = regval;
207 	file->private_data = wdt;
208 
209 	ts72xx_wdt_start(wdt);
210 
211 	mutex_unlock(&wdt->lock);
212 	return nonseekable_open(inode, file);
213 }
214 
215 static int ts72xx_wdt_release(struct inode *inode, struct file *file)
216 {
217 	struct ts72xx_wdt *wdt = file->private_data;
218 
219 	if (mutex_lock_interruptible(&wdt->lock))
220 		return -ERESTARTSYS;
221 
222 	if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
223 		ts72xx_wdt_stop(wdt);
224 	} else {
225 		dev_warn(&wdt->pdev->dev,
226 			 "TS-72XX WDT device closed unexpectly. "
227 			 "Watchdog timer will not stop!\n");
228 		/*
229 		 * Kick it one more time, to give userland some time
230 		 * to recover (for example, respawning the kicker
231 		 * daemon).
232 		 */
233 		ts72xx_wdt_kick(wdt);
234 	}
235 
236 	wdt->flags = 0;
237 
238 	mutex_unlock(&wdt->lock);
239 	return 0;
240 }
241 
242 static ssize_t ts72xx_wdt_write(struct file *file,
243 				const char __user *data,
244 				size_t len,
245 				loff_t *ppos)
246 {
247 	struct ts72xx_wdt *wdt = file->private_data;
248 
249 	if (!len)
250 		return 0;
251 
252 	if (mutex_lock_interruptible(&wdt->lock))
253 		return -ERESTARTSYS;
254 
255 	ts72xx_wdt_kick(wdt);
256 
257 	/*
258 	 * Support for magic character closing. User process
259 	 * writes 'V' into the device, just before it is closed.
260 	 * This means that we know that the wdt timer can be
261 	 * stopped after user closes the device.
262 	 */
263 	if (!nowayout) {
264 		int i;
265 
266 		for (i = 0; i < len; i++) {
267 			char c;
268 
269 			/* In case it was set long ago */
270 			wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
271 
272 			if (get_user(c, data + i)) {
273 				mutex_unlock(&wdt->lock);
274 				return -EFAULT;
275 			}
276 			if (c == 'V') {
277 				wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
278 				break;
279 			}
280 		}
281 	}
282 
283 	mutex_unlock(&wdt->lock);
284 	return len;
285 }
286 
287 static const struct watchdog_info winfo = {
288 	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
289 				  WDIOF_MAGICCLOSE,
290 	.firmware_version	= 1,
291 	.identity		= "TS-72XX WDT",
292 };
293 
294 static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
295 			     unsigned long arg)
296 {
297 	struct ts72xx_wdt *wdt = file->private_data;
298 	void __user *argp = (void __user *)arg;
299 	int __user *p = (int __user *)argp;
300 	int error = 0;
301 
302 	if (mutex_lock_interruptible(&wdt->lock))
303 		return -ERESTARTSYS;
304 
305 	switch (cmd) {
306 	case WDIOC_GETSUPPORT:
307 		error = copy_to_user(argp, &winfo, sizeof(winfo));
308 		break;
309 
310 	case WDIOC_GETSTATUS:
311 	case WDIOC_GETBOOTSTATUS:
312 		return put_user(0, p);
313 
314 	case WDIOC_KEEPALIVE:
315 		ts72xx_wdt_kick(wdt);
316 		break;
317 
318 	case WDIOC_SETOPTIONS: {
319 		int options;
320 
321 		if (get_user(options, p)) {
322 			error = -EFAULT;
323 			break;
324 		}
325 
326 		error = -EINVAL;
327 
328 		if ((options & WDIOS_DISABLECARD) != 0) {
329 			ts72xx_wdt_stop(wdt);
330 			error = 0;
331 		}
332 		if ((options & WDIOS_ENABLECARD) != 0) {
333 			ts72xx_wdt_start(wdt);
334 			error = 0;
335 		}
336 
337 		break;
338 	}
339 
340 	case WDIOC_SETTIMEOUT: {
341 		int new_timeout;
342 
343 		if (get_user(new_timeout, p)) {
344 			error = -EFAULT;
345 		} else {
346 			int regval;
347 
348 			regval = timeout_to_regval(new_timeout);
349 			if (regval < 0) {
350 				error = -EINVAL;
351 			} else {
352 				ts72xx_wdt_stop(wdt);
353 				wdt->regval = regval;
354 				ts72xx_wdt_start(wdt);
355 			}
356 		}
357 		if (error)
358 			break;
359 
360 		/*FALLTHROUGH*/
361 	}
362 
363 	case WDIOC_GETTIMEOUT:
364 		if (put_user(regval_to_timeout(wdt->regval), p))
365 			error = -EFAULT;
366 		break;
367 
368 	default:
369 		error = -ENOTTY;
370 		break;
371 	}
372 
373 	mutex_unlock(&wdt->lock);
374 	return error;
375 }
376 
377 static const struct file_operations ts72xx_wdt_fops = {
378 	.owner		= THIS_MODULE,
379 	.llseek		= no_llseek,
380 	.open		= ts72xx_wdt_open,
381 	.release	= ts72xx_wdt_release,
382 	.write		= ts72xx_wdt_write,
383 	.unlocked_ioctl	= ts72xx_wdt_ioctl,
384 };
385 
386 static struct miscdevice ts72xx_wdt_miscdev = {
387 	.minor		= WATCHDOG_MINOR,
388 	.name		= "watchdog",
389 	.fops		= &ts72xx_wdt_fops,
390 };
391 
392 static __devinit int ts72xx_wdt_probe(struct platform_device *pdev)
393 {
394 	struct ts72xx_wdt *wdt;
395 	struct resource *r1, *r2;
396 	int error = 0;
397 
398 	wdt = kzalloc(sizeof(struct ts72xx_wdt), GFP_KERNEL);
399 	if (!wdt) {
400 		dev_err(&pdev->dev, "failed to allocate memory\n");
401 		return -ENOMEM;
402 	}
403 
404 	r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
405 	if (!r1) {
406 		dev_err(&pdev->dev, "failed to get memory resource\n");
407 		error = -ENODEV;
408 		goto fail;
409 	}
410 
411 	r1 = request_mem_region(r1->start, resource_size(r1), pdev->name);
412 	if (!r1) {
413 		dev_err(&pdev->dev, "cannot request memory region\n");
414 		error = -EBUSY;
415 		goto fail;
416 	}
417 
418 	wdt->control_reg = ioremap(r1->start, resource_size(r1));
419 	if (!wdt->control_reg) {
420 		dev_err(&pdev->dev, "failed to map memory\n");
421 		error = -ENODEV;
422 		goto fail_free_control;
423 	}
424 
425 	r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
426 	if (!r2) {
427 		dev_err(&pdev->dev, "failed to get memory resource\n");
428 		error = -ENODEV;
429 		goto fail_unmap_control;
430 	}
431 
432 	r2 = request_mem_region(r2->start, resource_size(r2), pdev->name);
433 	if (!r2) {
434 		dev_err(&pdev->dev, "cannot request memory region\n");
435 		error = -EBUSY;
436 		goto fail_unmap_control;
437 	}
438 
439 	wdt->feed_reg = ioremap(r2->start, resource_size(r2));
440 	if (!wdt->feed_reg) {
441 		dev_err(&pdev->dev, "failed to map memory\n");
442 		error = -ENODEV;
443 		goto fail_free_feed;
444 	}
445 
446 	platform_set_drvdata(pdev, wdt);
447 	ts72xx_wdt_pdev = pdev;
448 	wdt->pdev = pdev;
449 	mutex_init(&wdt->lock);
450 
451 	error = misc_register(&ts72xx_wdt_miscdev);
452 	if (error) {
453 		dev_err(&pdev->dev, "failed to register miscdev\n");
454 		goto fail_unmap_feed;
455 	}
456 
457 	dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
458 
459 	return 0;
460 
461 fail_unmap_feed:
462 	platform_set_drvdata(pdev, NULL);
463 	iounmap(wdt->feed_reg);
464 fail_free_feed:
465 	release_mem_region(r2->start, resource_size(r2));
466 fail_unmap_control:
467 	iounmap(wdt->control_reg);
468 fail_free_control:
469 	release_mem_region(r1->start, resource_size(r1));
470 fail:
471 	kfree(wdt);
472 	return error;
473 }
474 
475 static __devexit int ts72xx_wdt_remove(struct platform_device *pdev)
476 {
477 	struct ts72xx_wdt *wdt = platform_get_drvdata(pdev);
478 	struct resource *res;
479 	int error;
480 
481 	error = misc_deregister(&ts72xx_wdt_miscdev);
482 	platform_set_drvdata(pdev, NULL);
483 
484 	iounmap(wdt->feed_reg);
485 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
486 	release_mem_region(res->start, resource_size(res));
487 
488 	iounmap(wdt->control_reg);
489 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
490 	release_mem_region(res->start, resource_size(res));
491 
492 	kfree(wdt);
493 	return error;
494 }
495 
496 static struct platform_driver ts72xx_wdt_driver = {
497 	.probe		= ts72xx_wdt_probe,
498 	.remove		= __devexit_p(ts72xx_wdt_remove),
499 	.driver		= {
500 		.name	= "ts72xx-wdt",
501 		.owner	= THIS_MODULE,
502 	},
503 };
504 
505 static __init int ts72xx_wdt_init(void)
506 {
507 	return platform_driver_register(&ts72xx_wdt_driver);
508 }
509 module_init(ts72xx_wdt_init);
510 
511 static __exit void ts72xx_wdt_exit(void)
512 {
513 	platform_driver_unregister(&ts72xx_wdt_driver);
514 }
515 module_exit(ts72xx_wdt_exit);
516 
517 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
518 MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
519 MODULE_LICENSE("GPL");
520 MODULE_ALIAS("platform:ts72xx-wdt");
521