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
wm831x_wdt_set_timeout(struct wm831x * wm831x,u16 value)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
wm831x_wdt_start(struct wm831x * wm831x)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
wm831x_wdt_stop(struct wm831x * wm831x)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
wm831x_wdt_kick(struct wm831x * wm831x)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
wm831x_wdt_open(struct inode * inode,struct file * file)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
wm831x_wdt_release(struct inode * inode,struct file * file)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
wm831x_wdt_write(struct file * file,const char __user * data,size_t count,loff_t * ppos)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
wm831x_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
wm831x_wdt_probe(struct platform_device * pdev)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 wm831x = dev_get_drvdata(pdev->dev.parent);
324
325 ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
326 if (ret < 0) {
327 dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
328 ret);
329 goto err;
330 }
331 reg = ret;
332
333 if (reg & WM831X_WDOG_DEBUG)
334 dev_warn(wm831x->dev, "Watchdog is paused\n");
335
336 /* Apply any configuration */
337 if (pdev->dev.parent->platform_data) {
338 chip_pdata = pdev->dev.parent->platform_data;
339 pdata = chip_pdata->watchdog;
340 } else {
341 pdata = NULL;
342 }
343
344 if (pdata) {
345 reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
346 WM831X_WDOG_RST_SRC);
347
348 reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
349 reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
350 reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
351
352 if (pdata->update_gpio) {
353 ret = gpio_request(pdata->update_gpio,
354 "Watchdog update");
355 if (ret < 0) {
356 dev_err(wm831x->dev,
357 "Failed to request update GPIO: %d\n",
358 ret);
359 goto err;
360 }
361
362 ret = gpio_direction_output(pdata->update_gpio, 0);
363 if (ret != 0) {
364 dev_err(wm831x->dev,
365 "gpio_direction_output returned: %d\n",
366 ret);
367 goto err_gpio;
368 }
369
370 update_gpio = pdata->update_gpio;
371
372 /* Make sure the watchdog takes hardware updates */
373 reg |= WM831X_WDOG_RST_SRC;
374 }
375
376 ret = wm831x_reg_unlock(wm831x);
377 if (ret == 0) {
378 ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
379 wm831x_reg_lock(wm831x);
380 } else {
381 dev_err(wm831x->dev,
382 "Failed to unlock security key: %d\n", ret);
383 goto err_gpio;
384 }
385 }
386
387 wm831x_wdt_miscdev.parent = &pdev->dev;
388
389 ret = misc_register(&wm831x_wdt_miscdev);
390 if (ret != 0) {
391 dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
392 goto err_gpio;
393 }
394
395 return 0;
396
397 err_gpio:
398 if (update_gpio) {
399 gpio_free(update_gpio);
400 update_gpio = 0;
401 }
402 err:
403 return ret;
404 }
405
wm831x_wdt_remove(struct platform_device * pdev)406 static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
407 {
408 if (update_gpio) {
409 gpio_free(update_gpio);
410 update_gpio = 0;
411 }
412
413 misc_deregister(&wm831x_wdt_miscdev);
414
415 return 0;
416 }
417
418 static struct platform_driver wm831x_wdt_driver = {
419 .probe = wm831x_wdt_probe,
420 .remove = __devexit_p(wm831x_wdt_remove),
421 .driver = {
422 .name = "wm831x-watchdog",
423 },
424 };
425
wm831x_wdt_init(void)426 static int __init wm831x_wdt_init(void)
427 {
428 return platform_driver_register(&wm831x_wdt_driver);
429 }
430 module_init(wm831x_wdt_init);
431
wm831x_wdt_exit(void)432 static void __exit wm831x_wdt_exit(void)
433 {
434 platform_driver_unregister(&wm831x_wdt_driver);
435 }
436 module_exit(wm831x_wdt_exit);
437
438 MODULE_AUTHOR("Mark Brown");
439 MODULE_DESCRIPTION("WM831x Watchdog");
440 MODULE_LICENSE("GPL");
441 MODULE_ALIAS("platform:wm831x-watchdog");
442