xref: /openbmc/linux/drivers/watchdog/ts72xx_wdt.c (revision bc000245) 
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/slab.h>
24 #include <linux/watchdog.h>
25 #include <linux/uaccess.h>
26 
27 #define TS72XX_WDT_FEED_VAL		0x05
28 #define TS72XX_WDT_DEFAULT_TIMEOUT	8
29 
30 static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
31 module_param(timeout, int, 0);
32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
33 			  "(1 <= timeout <= 8, default="
34 			  __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
35 			  ")");
36 
37 static bool nowayout = WATCHDOG_NOWAYOUT;
38 module_param(nowayout, bool, 0);
39 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
40 
41 /**
42  * struct ts72xx_wdt - watchdog control structure
43  * @lock: lock that protects this structure
44  * @regval: watchdog timeout value suitable for control register
45  * @flags: flags controlling watchdog device state
46  * @control_reg: watchdog control register
47  * @feed_reg: watchdog feed register
48  * @pdev: back pointer to platform dev
49  */
50 struct ts72xx_wdt {
51 	struct mutex	lock;
52 	int		regval;
53 
54 #define TS72XX_WDT_BUSY_FLAG		1
55 #define TS72XX_WDT_EXPECT_CLOSE_FLAG	2
56 	int		flags;
57 
58 	void __iomem	*control_reg;
59 	void __iomem	*feed_reg;
60 
61 	struct platform_device *pdev;
62 };
63 
64 struct platform_device *ts72xx_wdt_pdev;
65 
66 /*
67  * TS-72xx Watchdog supports following timeouts (value written
68  * to control register):
69  *	value	description
70  *	-------------------------
71  *	0x00	watchdog disabled
72  *	0x01	250ms
73  *	0x02	500ms
74  *	0x03	1s
75  *	0x04	reserved
76  *	0x05	2s
77  *	0x06	4s
78  *	0x07	8s
79  *
80  * Timeouts below 1s are not very usable so we don't
81  * allow them at all.
82  *
83  * We provide two functions that convert between these:
84  * timeout_to_regval() and regval_to_timeout().
85  */
86 static const struct {
87 	int	timeout;
88 	int	regval;
89 } ts72xx_wdt_map[] = {
90 	{ 1, 3 },
91 	{ 2, 5 },
92 	{ 4, 6 },
93 	{ 8, 7 },
94 };
95 
96 /**
97  * timeout_to_regval() - converts given timeout to control register value
98  * @new_timeout: timeout in seconds to be converted
99  *
100  * Function converts given @new_timeout into valid value that can
101  * be programmed into watchdog control register. When conversion is
102  * not possible, function returns %-EINVAL.
103  */
104 static int timeout_to_regval(int new_timeout)
105 {
106 	int i;
107 
108 	/* first limit it to 1 - 8 seconds */
109 	new_timeout = clamp_val(new_timeout, 1, 8);
110 
111 	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
112 		if (ts72xx_wdt_map[i].timeout >= new_timeout)
113 			return ts72xx_wdt_map[i].regval;
114 	}
115 
116 	return -EINVAL;
117 }
118 
119 /**
120  * regval_to_timeout() - converts control register value to timeout
121  * @regval: control register value to be converted
122  *
123  * Function converts given @regval to timeout in seconds (1, 2, 4 or 8).
124  * If @regval cannot be converted, function returns %-EINVAL.
125  */
126 static int regval_to_timeout(int regval)
127 {
128 	int i;
129 
130 	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
131 		if (ts72xx_wdt_map[i].regval == regval)
132 			return ts72xx_wdt_map[i].timeout;
133 	}
134 
135 	return -EINVAL;
136 }
137 
138 /**
139  * ts72xx_wdt_kick() - kick the watchdog
140  * @wdt: watchdog to be kicked
141  *
142  * Called with @wdt->lock held.
143  */
144 static inline void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
145 {
146 	__raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
147 }
148 
149 /**
150  * ts72xx_wdt_start() - starts the watchdog timer
151  * @wdt: watchdog to be started
152  *
153  * This function programs timeout to watchdog timer
154  * and starts it.
155  *
156  * Called with @wdt->lock held.
157  */
158 static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
159 {
160 	/*
161 	 * To program the wdt, it first must be "fed" and
162 	 * only after that (within 30 usecs) the configuration
163 	 * can be changed.
164 	 */
165 	ts72xx_wdt_kick(wdt);
166 	__raw_writeb((u8)wdt->regval, wdt->control_reg);
167 }
168 
169 /**
170  * ts72xx_wdt_stop() - stops the watchdog timer
171  * @wdt: watchdog to be stopped
172  *
173  * Called with @wdt->lock held.
174  */
175 static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
176 {
177 	ts72xx_wdt_kick(wdt);
178 	__raw_writeb(0, wdt->control_reg);
179 }
180 
181 static int ts72xx_wdt_open(struct inode *inode, struct file *file)
182 {
183 	struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
184 	int regval;
185 
186 	/*
187 	 * Try to convert default timeout to valid register
188 	 * value first.
189 	 */
190 	regval = timeout_to_regval(timeout);
191 	if (regval < 0) {
192 		dev_err(&wdt->pdev->dev,
193 			"failed to convert timeout (%d) to register value\n",
194 			timeout);
195 		return regval;
196 	}
197 
198 	if (mutex_lock_interruptible(&wdt->lock))
199 		return -ERESTARTSYS;
200 
201 	if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
202 		mutex_unlock(&wdt->lock);
203 		return -EBUSY;
204 	}
205 
206 	wdt->flags = TS72XX_WDT_BUSY_FLAG;
207 	wdt->regval = regval;
208 	file->private_data = wdt;
209 
210 	ts72xx_wdt_start(wdt);
211 
212 	mutex_unlock(&wdt->lock);
213 	return nonseekable_open(inode, file);
214 }
215 
216 static int ts72xx_wdt_release(struct inode *inode, struct file *file)
217 {
218 	struct ts72xx_wdt *wdt = file->private_data;
219 
220 	if (mutex_lock_interruptible(&wdt->lock))
221 		return -ERESTARTSYS;
222 
223 	if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
224 		ts72xx_wdt_stop(wdt);
225 	} else {
226 		dev_warn(&wdt->pdev->dev,
227 			 "TS-72XX WDT device closed unexpectly. "
228 			 "Watchdog timer will not stop!\n");
229 		/*
230 		 * Kick it one more time, to give userland some time
231 		 * to recover (for example, respawning the kicker
232 		 * daemon).
233 		 */
234 		ts72xx_wdt_kick(wdt);
235 	}
236 
237 	wdt->flags = 0;
238 
239 	mutex_unlock(&wdt->lock);
240 	return 0;
241 }
242 
243 static ssize_t ts72xx_wdt_write(struct file *file,
244 				const char __user *data,
245 				size_t len,
246 				loff_t *ppos)
247 {
248 	struct ts72xx_wdt *wdt = file->private_data;
249 
250 	if (!len)
251 		return 0;
252 
253 	if (mutex_lock_interruptible(&wdt->lock))
254 		return -ERESTARTSYS;
255 
256 	ts72xx_wdt_kick(wdt);
257 
258 	/*
259 	 * Support for magic character closing. User process
260 	 * writes 'V' into the device, just before it is closed.
261 	 * This means that we know that the wdt timer can be
262 	 * stopped after user closes the device.
263 	 */
264 	if (!nowayout) {
265 		int i;
266 
267 		for (i = 0; i < len; i++) {
268 			char c;
269 
270 			/* In case it was set long ago */
271 			wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
272 
273 			if (get_user(c, data + i)) {
274 				mutex_unlock(&wdt->lock);
275 				return -EFAULT;
276 			}
277 			if (c == 'V') {
278 				wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
279 				break;
280 			}
281 		}
282 	}
283 
284 	mutex_unlock(&wdt->lock);
285 	return len;
286 }
287 
288 static const struct watchdog_info winfo = {
289 	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
290 				  WDIOF_MAGICCLOSE,
291 	.firmware_version	= 1,
292 	.identity		= "TS-72XX WDT",
293 };
294 
295 static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
296 			     unsigned long arg)
297 {
298 	struct ts72xx_wdt *wdt = file->private_data;
299 	void __user *argp = (void __user *)arg;
300 	int __user *p = (int __user *)argp;
301 	int error = 0;
302 
303 	if (mutex_lock_interruptible(&wdt->lock))
304 		return -ERESTARTSYS;
305 
306 	switch (cmd) {
307 	case WDIOC_GETSUPPORT:
308 		if (copy_to_user(argp, &winfo, sizeof(winfo)))
309 			error = -EFAULT;
310 		break;
311 
312 	case WDIOC_GETSTATUS:
313 	case WDIOC_GETBOOTSTATUS:
314 		error = put_user(0, p);
315 		break;
316 
317 	case WDIOC_KEEPALIVE:
318 		ts72xx_wdt_kick(wdt);
319 		break;
320 
321 	case WDIOC_SETOPTIONS: {
322 		int options;
323 
324 		error = get_user(options, p);
325 		if (error)
326 			break;
327 
328 		error = -EINVAL;
329 
330 		if ((options & WDIOS_DISABLECARD) != 0) {
331 			ts72xx_wdt_stop(wdt);
332 			error = 0;
333 		}
334 		if ((options & WDIOS_ENABLECARD) != 0) {
335 			ts72xx_wdt_start(wdt);
336 			error = 0;
337 		}
338 
339 		break;
340 	}
341 
342 	case WDIOC_SETTIMEOUT: {
343 		int new_timeout;
344 		int regval;
345 
346 		error = get_user(new_timeout, p);
347 		if (error)
348 			break;
349 
350 		regval = timeout_to_regval(new_timeout);
351 		if (regval < 0) {
352 			error = regval;
353 			break;
354 		}
355 		ts72xx_wdt_stop(wdt);
356 		wdt->regval = regval;
357 		ts72xx_wdt_start(wdt);
358 
359 		/*FALLTHROUGH*/
360 	}
361 
362 	case WDIOC_GETTIMEOUT:
363 		error = put_user(regval_to_timeout(wdt->regval), p);
364 		break;
365 
366 	default:
367 		error = -ENOTTY;
368 		break;
369 	}
370 
371 	mutex_unlock(&wdt->lock);
372 	return error;
373 }
374 
375 static const struct file_operations ts72xx_wdt_fops = {
376 	.owner		= THIS_MODULE,
377 	.llseek		= no_llseek,
378 	.open		= ts72xx_wdt_open,
379 	.release	= ts72xx_wdt_release,
380 	.write		= ts72xx_wdt_write,
381 	.unlocked_ioctl	= ts72xx_wdt_ioctl,
382 };
383 
384 static struct miscdevice ts72xx_wdt_miscdev = {
385 	.minor		= WATCHDOG_MINOR,
386 	.name		= "watchdog",
387 	.fops		= &ts72xx_wdt_fops,
388 };
389 
390 static int ts72xx_wdt_probe(struct platform_device *pdev)
391 {
392 	struct ts72xx_wdt *wdt;
393 	struct resource *r1, *r2;
394 	int error = 0;
395 
396 	wdt = devm_kzalloc(&pdev->dev, sizeof(struct ts72xx_wdt), GFP_KERNEL);
397 	if (!wdt) {
398 		dev_err(&pdev->dev, "failed to allocate memory\n");
399 		return -ENOMEM;
400 	}
401 
402 	r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
403 	wdt->control_reg = devm_ioremap_resource(&pdev->dev, r1);
404 	if (IS_ERR(wdt->control_reg))
405 		return PTR_ERR(wdt->control_reg);
406 
407 	r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
408 	wdt->feed_reg = devm_ioremap_resource(&pdev->dev, r2);
409 	if (IS_ERR(wdt->feed_reg))
410 		return PTR_ERR(wdt->feed_reg);
411 
412 	platform_set_drvdata(pdev, wdt);
413 	ts72xx_wdt_pdev = pdev;
414 	wdt->pdev = pdev;
415 	mutex_init(&wdt->lock);
416 
417 	/* make sure that the watchdog is disabled */
418 	ts72xx_wdt_stop(wdt);
419 
420 	error = misc_register(&ts72xx_wdt_miscdev);
421 	if (error) {
422 		dev_err(&pdev->dev, "failed to register miscdev\n");
423 		return error;
424 	}
425 
426 	dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
427 
428 	return 0;
429 }
430 
431 static int ts72xx_wdt_remove(struct platform_device *pdev)
432 {
433 	int error;
434 
435 	error = misc_deregister(&ts72xx_wdt_miscdev);
436 
437 	return error;
438 }
439 
440 static struct platform_driver ts72xx_wdt_driver = {
441 	.probe		= ts72xx_wdt_probe,
442 	.remove		= ts72xx_wdt_remove,
443 	.driver		= {
444 		.name	= "ts72xx-wdt",
445 		.owner	= THIS_MODULE,
446 	},
447 };
448 
449 module_platform_driver(ts72xx_wdt_driver);
450 
451 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
452 MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
453 MODULE_LICENSE("GPL");
454 MODULE_ALIAS("platform:ts72xx-wdt");
455