[WATCHDOG] ep93xx: implemented watchdog timer driver for TS-72xx SBCs
[linux-2.6.git] / drivers / watchdog / ts72xx_wdt.c
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_KEEPALIVE:
311                 ts72xx_wdt_kick(wdt);
312                 break;
313
314         case WDIOC_SETOPTIONS: {
315                 int options;
316
317                 if (get_user(options, p)) {
318                         error = -EFAULT;
319                         break;
320                 }
321
322                 error = -EINVAL;
323
324                 if ((options & WDIOS_DISABLECARD) != 0) {
325                         ts72xx_wdt_stop(wdt);
326                         error = 0;
327                 }
328                 if ((options & WDIOS_ENABLECARD) != 0) {
329                         ts72xx_wdt_start(wdt);
330                         error = 0;
331                 }
332
333                 break;
334         }
335
336         case WDIOC_SETTIMEOUT: {
337                 int new_timeout;
338
339                 if (get_user(new_timeout, p)) {
340                         error = -EFAULT;
341                 } else {
342                         int regval;
343
344                         regval = timeout_to_regval(new_timeout);
345                         if (regval < 0) {
346                                 error = -EINVAL;
347                         } else {
348                                 ts72xx_wdt_stop(wdt);
349                                 wdt->regval = regval;
350                                 ts72xx_wdt_start(wdt);
351                         }
352                 }
353                 if (error)
354                         break;
355
356                 /*FALLTHROUGH*/
357         }
358
359         case WDIOC_GETTIMEOUT:
360                 if (put_user(regval_to_timeout(wdt->regval), p))
361                         error = -EFAULT;
362                 break;
363
364         default:
365                 error = -ENOTTY;
366                 break;
367         }
368
369         mutex_unlock(&wdt->lock);
370         return error;
371 }
372
373 static const struct file_operations ts72xx_wdt_fops = {
374         .owner          = THIS_MODULE,
375         .llseek         = no_llseek,
376         .open           = ts72xx_wdt_open,
377         .release        = ts72xx_wdt_release,
378         .write          = ts72xx_wdt_write,
379         .unlocked_ioctl = ts72xx_wdt_ioctl,
380 };
381
382 static struct miscdevice ts72xx_wdt_miscdev = {
383         .minor          = WATCHDOG_MINOR,
384         .name           = "watchdog",
385         .fops           = &ts72xx_wdt_fops,
386 };
387
388 static __devinit int ts72xx_wdt_probe(struct platform_device *pdev)
389 {
390         struct ts72xx_wdt *wdt;
391         struct resource *r1, *r2;
392         int error = 0;
393
394         wdt = kzalloc(sizeof(struct ts72xx_wdt), GFP_KERNEL);
395         if (!wdt) {
396                 dev_err(&pdev->dev, "failed to allocate memory\n");
397                 return -ENOMEM;
398         }
399
400         r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
401         if (!r1) {
402                 dev_err(&pdev->dev, "failed to get memory resource\n");
403                 error = -ENODEV;
404                 goto fail;
405         }
406
407         r1 = request_mem_region(r1->start, resource_size(r1), pdev->name);
408         if (!r1) {
409                 dev_err(&pdev->dev, "cannot request memory region\n");
410                 error = -EBUSY;
411                 goto fail;
412         }
413
414         wdt->control_reg = ioremap(r1->start, resource_size(r1));
415         if (!wdt->control_reg) {
416                 dev_err(&pdev->dev, "failed to map memory\n");
417                 error = -ENODEV;
418                 goto fail_free_control;
419         }
420
421         r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
422         if (!r2) {
423                 dev_err(&pdev->dev, "failed to get memory resource\n");
424                 error = -ENODEV;
425                 goto fail_unmap_control;
426         }
427
428         r2 = request_mem_region(r2->start, resource_size(r2), pdev->name);
429         if (!r2) {
430                 dev_err(&pdev->dev, "cannot request memory region\n");
431                 error = -EBUSY;
432                 goto fail_unmap_control;
433         }
434
435         wdt->feed_reg = ioremap(r2->start, resource_size(r2));
436         if (!wdt->feed_reg) {
437                 dev_err(&pdev->dev, "failed to map memory\n");
438                 error = -ENODEV;
439                 goto fail_free_feed;
440         }
441
442         platform_set_drvdata(pdev, wdt);
443         ts72xx_wdt_pdev = pdev;
444         wdt->pdev = pdev;
445         mutex_init(&wdt->lock);
446
447         error = misc_register(&ts72xx_wdt_miscdev);
448         if (error) {
449                 dev_err(&pdev->dev, "failed to register miscdev\n");
450                 goto fail_unmap_feed;
451         }
452
453         dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
454
455         return 0;
456
457 fail_unmap_feed:
458         platform_set_drvdata(pdev, NULL);
459         iounmap(wdt->feed_reg);
460 fail_free_feed:
461         release_mem_region(r2->start, resource_size(r2));
462 fail_unmap_control:
463         iounmap(wdt->control_reg);
464 fail_free_control:
465         release_mem_region(r1->start, resource_size(r1));
466 fail:
467         kfree(wdt);
468         return error;
469 }
470
471 static __devexit int ts72xx_wdt_remove(struct platform_device *pdev)
472 {
473         struct ts72xx_wdt *wdt = platform_get_drvdata(pdev);
474         struct resource *res;
475         int error;
476
477         error = misc_deregister(&ts72xx_wdt_miscdev);
478         platform_set_drvdata(pdev, NULL);
479
480         iounmap(wdt->control_reg);
481         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
482         release_mem_region(res->start, resource_size(res));
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         kfree(wdt);
489         return error;
490 }
491
492 static struct platform_driver ts72xx_wdt_driver = {
493         .probe          = ts72xx_wdt_probe,
494         .remove         = __devexit_p(ts72xx_wdt_remove),
495         .driver         = {
496                 .name   = "ts72xx-wdt",
497                 .owner  = THIS_MODULE,
498         },
499 };
500
501 static __init int ts72xx_wdt_init(void)
502 {
503         return platform_driver_register(&ts72xx_wdt_driver);
504 }
505 module_init(ts72xx_wdt_init);
506
507 static __exit void ts72xx_wdt_exit(void)
508 {
509         platform_driver_unregister(&ts72xx_wdt_driver);
510 }
511 module_exit(ts72xx_wdt_exit);
512
513 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
514 MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
515 MODULE_LICENSE("GPL");
516 MODULE_ALIAS("platform:ts72xx-wdt");