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[linux-2.6.git] / drivers / watchdog / wm831x_wdt.c
1 /*
2  * Watchdog driver for the wm831x PMICs
3  *
4  * Copyright (C) 2009 Wolfson Microelectronics
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation
9  */
10
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/fs.h>
16 #include <linux/miscdevice.h>
17 #include <linux/platform_device.h>
18 #include <linux/watchdog.h>
19 #include <linux/uaccess.h>
20 #include <linux/gpio.h>
21
22 #include <linux/mfd/wm831x/core.h>
23 #include <linux/mfd/wm831x/pdata.h>
24 #include <linux/mfd/wm831x/watchdog.h>
25
26 static int nowayout = WATCHDOG_NOWAYOUT;
27 module_param(nowayout, int, 0);
28 MODULE_PARM_DESC(nowayout,
29                  "Watchdog cannot be stopped once started (default="
30                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
31
32 static unsigned long wm831x_wdt_users;
33 static struct miscdevice wm831x_wdt_miscdev;
34 static int wm831x_wdt_expect_close;
35 static DEFINE_MUTEX(wdt_mutex);
36 static struct wm831x *wm831x;
37 static unsigned int update_gpio;
38 static unsigned int update_state;
39
40 /* We can't use the sub-second values here but they're included
41  * for completeness.  */
42 static struct {
43         int time;  /* Seconds */
44         u16 val;   /* WDOG_TO value */
45 } wm831x_wdt_cfgs[] = {
46         {  1, 2 },
47         {  2, 3 },
48         {  4, 4 },
49         {  8, 5 },
50         { 16, 6 },
51         { 32, 7 },
52         { 33, 7 },  /* Actually 32.768s so include both, others round down */
53 };
54
55 static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
56 {
57         int ret;
58
59         mutex_lock(&wdt_mutex);
60
61         ret = wm831x_reg_unlock(wm831x);
62         if (ret == 0) {
63                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
64                                       WM831X_WDOG_TO_MASK, value);
65                 wm831x_reg_lock(wm831x);
66         } else {
67                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
68                         ret);
69         }
70
71         mutex_unlock(&wdt_mutex);
72
73         return ret;
74 }
75
76 static int wm831x_wdt_start(struct wm831x *wm831x)
77 {
78         int ret;
79
80         mutex_lock(&wdt_mutex);
81
82         ret = wm831x_reg_unlock(wm831x);
83         if (ret == 0) {
84                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
85                                       WM831X_WDOG_ENA, WM831X_WDOG_ENA);
86                 wm831x_reg_lock(wm831x);
87         } else {
88                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
89                         ret);
90         }
91
92         mutex_unlock(&wdt_mutex);
93
94         return ret;
95 }
96
97 static int wm831x_wdt_stop(struct wm831x *wm831x)
98 {
99         int ret;
100
101         mutex_lock(&wdt_mutex);
102
103         ret = wm831x_reg_unlock(wm831x);
104         if (ret == 0) {
105                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
106                                       WM831X_WDOG_ENA, 0);
107                 wm831x_reg_lock(wm831x);
108         } else {
109                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
110                         ret);
111         }
112
113         mutex_unlock(&wdt_mutex);
114
115         return ret;
116 }
117
118 static int wm831x_wdt_kick(struct wm831x *wm831x)
119 {
120         int ret;
121         u16 reg;
122
123         mutex_lock(&wdt_mutex);
124
125         if (update_gpio) {
126                 gpio_set_value_cansleep(update_gpio, update_state);
127                 update_state = !update_state;
128                 ret = 0;
129                 goto out;
130         }
131
132
133         reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
134
135         if (!(reg & WM831X_WDOG_RST_SRC)) {
136                 dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
137                 ret = -EINVAL;
138                 goto out;
139         }
140
141         reg |= WM831X_WDOG_RESET;
142
143         ret = wm831x_reg_unlock(wm831x);
144         if (ret == 0) {
145                 ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
146                 wm831x_reg_lock(wm831x);
147         } else {
148                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
149                         ret);
150         }
151
152 out:
153         mutex_unlock(&wdt_mutex);
154
155         return ret;
156 }
157
158 static int wm831x_wdt_open(struct inode *inode, struct file *file)
159 {
160         int ret;
161
162         if (!wm831x)
163                 return -ENODEV;
164
165         if (test_and_set_bit(0, &wm831x_wdt_users))
166                 return -EBUSY;
167
168         ret = wm831x_wdt_start(wm831x);
169         if (ret != 0)
170                 return ret;
171
172         return nonseekable_open(inode, file);
173 }
174
175 static int wm831x_wdt_release(struct inode *inode, struct file *file)
176 {
177         if (wm831x_wdt_expect_close)
178                 wm831x_wdt_stop(wm831x);
179         else {
180                 dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
181                 wm831x_wdt_kick(wm831x);
182         }
183
184         clear_bit(0, &wm831x_wdt_users);
185
186         return 0;
187 }
188
189 static ssize_t wm831x_wdt_write(struct file *file,
190                                 const char __user *data, size_t count,
191                                 loff_t *ppos)
192 {
193         size_t i;
194
195         if (count) {
196                 wm831x_wdt_kick(wm831x);
197
198                 if (!nowayout) {
199                         /* In case it was set long ago */
200                         wm831x_wdt_expect_close = 0;
201
202                         /* scan to see whether or not we got the magic
203                            character */
204                         for (i = 0; i != count; i++) {
205                                 char c;
206                                 if (get_user(c, data + i))
207                                         return -EFAULT;
208                                 if (c == 'V')
209                                         wm831x_wdt_expect_close = 42;
210                         }
211                 }
212         }
213         return count;
214 }
215
216 static const struct watchdog_info ident = {
217         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
218         .identity = "WM831x Watchdog",
219 };
220
221 static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
222                              unsigned long arg)
223 {
224         int ret = -ENOTTY, time, i;
225         void __user *argp = (void __user *)arg;
226         int __user *p = argp;
227         u16 reg;
228
229         switch (cmd) {
230         case WDIOC_GETSUPPORT:
231                 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
232                 break;
233
234         case WDIOC_GETSTATUS:
235         case WDIOC_GETBOOTSTATUS:
236                 ret = put_user(0, p);
237                 break;
238
239         case WDIOC_SETOPTIONS:
240         {
241                 int options;
242
243                 if (get_user(options, p))
244                         return -EFAULT;
245
246                 ret = -EINVAL;
247
248                 /* Setting both simultaneously means at least one must fail */
249                 if (options == WDIOS_DISABLECARD)
250                         ret = wm831x_wdt_start(wm831x);
251
252                 if (options == WDIOS_ENABLECARD)
253                         ret = wm831x_wdt_stop(wm831x);
254                 break;
255         }
256
257         case WDIOC_KEEPALIVE:
258                 ret = wm831x_wdt_kick(wm831x);
259                 break;
260
261         case WDIOC_SETTIMEOUT:
262                 ret = get_user(time, p);
263                 if (ret)
264                         break;
265
266                 if (time == 0) {
267                         if (nowayout)
268                                 ret = -EINVAL;
269                         else
270                                 wm831x_wdt_stop(wm831x);
271                         break;
272                 }
273
274                 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
275                         if (wm831x_wdt_cfgs[i].time == time)
276                                 break;
277                 if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
278                         ret = -EINVAL;
279                 else
280                         ret = wm831x_wdt_set_timeout(wm831x,
281                                                      wm831x_wdt_cfgs[i].val);
282                 break;
283
284         case WDIOC_GETTIMEOUT:
285                 reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
286                 reg &= WM831X_WDOG_TO_MASK;
287                 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
288                         if (wm831x_wdt_cfgs[i].val == reg)
289                                 break;
290                 if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
291                         dev_warn(wm831x->dev,
292                                  "Unknown watchdog configuration: %x\n", reg);
293                         ret = -EINVAL;
294                 } else
295                         ret = put_user(wm831x_wdt_cfgs[i].time, p);
296
297         }
298
299         return ret;
300 }
301
302 static const struct file_operations wm831x_wdt_fops = {
303         .owner = THIS_MODULE,
304         .llseek = no_llseek,
305         .write = wm831x_wdt_write,
306         .unlocked_ioctl = wm831x_wdt_ioctl,
307         .open = wm831x_wdt_open,
308         .release = wm831x_wdt_release,
309 };
310
311 static struct miscdevice wm831x_wdt_miscdev = {
312         .minor = WATCHDOG_MINOR,
313         .name = "watchdog",
314         .fops = &wm831x_wdt_fops,
315 };
316
317 static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
318 {
319         struct wm831x_pdata *chip_pdata;
320         struct wm831x_watchdog_pdata *pdata;
321         int reg, ret;
322
323         if (wm831x) {
324                 dev_err(&pdev->dev, "wm831x watchdog already registered\n");
325                 return -EBUSY;
326         }
327
328         wm831x = dev_get_drvdata(pdev->dev.parent);
329
330         ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
331         if (ret < 0) {
332                 dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
333                         ret);
334                 goto err;
335         }
336         reg = ret;
337
338         if (reg & WM831X_WDOG_DEBUG)
339                 dev_warn(wm831x->dev, "Watchdog is paused\n");
340
341         /* Apply any configuration */
342         if (pdev->dev.parent->platform_data) {
343                 chip_pdata = pdev->dev.parent->platform_data;
344                 pdata = chip_pdata->watchdog;
345         } else {
346                 pdata = NULL;
347         }
348
349         if (pdata) {
350                 reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
351                          WM831X_WDOG_RST_SRC);
352
353                 reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
354                 reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
355                 reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
356
357                 if (pdata->update_gpio) {
358                         ret = gpio_request(pdata->update_gpio,
359                                            "Watchdog update");
360                         if (ret < 0) {
361                                 dev_err(wm831x->dev,
362                                         "Failed to request update GPIO: %d\n",
363                                         ret);
364                                 goto err;
365                         }
366
367                         ret = gpio_direction_output(pdata->update_gpio, 0);
368                         if (ret != 0) {
369                                 dev_err(wm831x->dev,
370                                         "gpio_direction_output returned: %d\n",
371                                         ret);
372                                 goto err_gpio;
373                         }
374
375                         update_gpio = pdata->update_gpio;
376
377                         /* Make sure the watchdog takes hardware updates */
378                         reg |= WM831X_WDOG_RST_SRC;
379                 }
380
381                 ret = wm831x_reg_unlock(wm831x);
382                 if (ret == 0) {
383                         ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
384                         wm831x_reg_lock(wm831x);
385                 } else {
386                         dev_err(wm831x->dev,
387                                 "Failed to unlock security key: %d\n", ret);
388                         goto err_gpio;
389                 }
390         }
391
392         wm831x_wdt_miscdev.parent = &pdev->dev;
393
394         ret = misc_register(&wm831x_wdt_miscdev);
395         if (ret != 0) {
396                 dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
397                 goto err_gpio;
398         }
399
400         return 0;
401
402 err_gpio:
403         if (update_gpio) {
404                 gpio_free(update_gpio);
405                 update_gpio = 0;
406         }
407 err:
408         return ret;
409 }
410
411 static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
412 {
413         if (update_gpio) {
414                 gpio_free(update_gpio);
415                 update_gpio = 0;
416         }
417
418         misc_deregister(&wm831x_wdt_miscdev);
419
420         return 0;
421 }
422
423 static struct platform_driver wm831x_wdt_driver = {
424         .probe = wm831x_wdt_probe,
425         .remove = __devexit_p(wm831x_wdt_remove),
426         .driver = {
427                 .name = "wm831x-watchdog",
428         },
429 };
430
431 static int __init wm831x_wdt_init(void)
432 {
433         return platform_driver_register(&wm831x_wdt_driver);
434 }
435 module_init(wm831x_wdt_init);
436
437 static void __exit wm831x_wdt_exit(void)
438 {
439         platform_driver_unregister(&wm831x_wdt_driver);
440 }
441 module_exit(wm831x_wdt_exit);
442
443 MODULE_AUTHOR("Mark Brown");
444 MODULE_DESCRIPTION("WM831x Watchdog");
445 MODULE_LICENSE("GPL");
446 MODULE_ALIAS("platform:wm831x-watchdog");