1 /*
2 * Watchdog driver for the wm8350
3 *
4 * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.com>
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/mfd/wm8350/core.h>
21
22 static int nowayout = WATCHDOG_NOWAYOUT;
23 module_param(nowayout, int, 0);
24 MODULE_PARM_DESC(nowayout,
25 "Watchdog cannot be stopped once started (default="
26 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
27
28 static unsigned long wm8350_wdt_users;
29 static struct miscdevice wm8350_wdt_miscdev;
30 static int wm8350_wdt_expect_close;
31 static DEFINE_MUTEX(wdt_mutex);
32
33 static struct {
34 int time; /* Seconds */
35 u16 val; /* To be set in WM8350_SYSTEM_CONTROL_2 */
36 } wm8350_wdt_cfgs[] = {
37 { 1, 0x02 },
38 { 2, 0x04 },
39 { 4, 0x05 },
40 };
41
get_wm8350(void)42 static struct wm8350 *get_wm8350(void)
43 {
44 return dev_get_drvdata(wm8350_wdt_miscdev.parent);
45 }
46
wm8350_wdt_set_timeout(struct wm8350 * wm8350,u16 value)47 static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
48 {
49 int ret;
50 u16 reg;
51
52 mutex_lock(&wdt_mutex);
53 wm8350_reg_unlock(wm8350);
54
55 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
56 reg &= ~WM8350_WDOG_TO_MASK;
57 reg |= value;
58 ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
59
60 wm8350_reg_lock(wm8350);
61 mutex_unlock(&wdt_mutex);
62
63 return ret;
64 }
65
wm8350_wdt_start(struct wm8350 * wm8350)66 static int wm8350_wdt_start(struct wm8350 *wm8350)
67 {
68 int ret;
69 u16 reg;
70
71 mutex_lock(&wdt_mutex);
72 wm8350_reg_unlock(wm8350);
73
74 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
75 reg &= ~WM8350_WDOG_MODE_MASK;
76 reg |= 0x20;
77 ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
78
79 wm8350_reg_lock(wm8350);
80 mutex_unlock(&wdt_mutex);
81
82 return ret;
83 }
84
wm8350_wdt_stop(struct wm8350 * wm8350)85 static int wm8350_wdt_stop(struct wm8350 *wm8350)
86 {
87 int ret;
88 u16 reg;
89
90 mutex_lock(&wdt_mutex);
91 wm8350_reg_unlock(wm8350);
92
93 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
94 reg &= ~WM8350_WDOG_MODE_MASK;
95 ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
96
97 wm8350_reg_lock(wm8350);
98 mutex_unlock(&wdt_mutex);
99
100 return ret;
101 }
102
wm8350_wdt_kick(struct wm8350 * wm8350)103 static int wm8350_wdt_kick(struct wm8350 *wm8350)
104 {
105 int ret;
106 u16 reg;
107
108 mutex_lock(&wdt_mutex);
109
110 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
111 ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
112
113 mutex_unlock(&wdt_mutex);
114
115 return ret;
116 }
117
wm8350_wdt_open(struct inode * inode,struct file * file)118 static int wm8350_wdt_open(struct inode *inode, struct file *file)
119 {
120 struct wm8350 *wm8350 = get_wm8350();
121 int ret;
122
123 if (!wm8350)
124 return -ENODEV;
125
126 if (test_and_set_bit(0, &wm8350_wdt_users))
127 return -EBUSY;
128
129 ret = wm8350_wdt_start(wm8350);
130 if (ret != 0)
131 return ret;
132
133 return nonseekable_open(inode, file);
134 }
135
wm8350_wdt_release(struct inode * inode,struct file * file)136 static int wm8350_wdt_release(struct inode *inode, struct file *file)
137 {
138 struct wm8350 *wm8350 = get_wm8350();
139
140 if (wm8350_wdt_expect_close)
141 wm8350_wdt_stop(wm8350);
142 else {
143 dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
144 wm8350_wdt_kick(wm8350);
145 }
146
147 clear_bit(0, &wm8350_wdt_users);
148
149 return 0;
150 }
151
wm8350_wdt_write(struct file * file,const char __user * data,size_t count,loff_t * ppos)152 static ssize_t wm8350_wdt_write(struct file *file,
153 const char __user *data, size_t count,
154 loff_t *ppos)
155 {
156 struct wm8350 *wm8350 = get_wm8350();
157 size_t i;
158
159 if (count) {
160 wm8350_wdt_kick(wm8350);
161
162 if (!nowayout) {
163 /* In case it was set long ago */
164 wm8350_wdt_expect_close = 0;
165
166 /* scan to see whether or not we got the magic
167 character */
168 for (i = 0; i != count; i++) {
169 char c;
170 if (get_user(c, data + i))
171 return -EFAULT;
172 if (c == 'V')
173 wm8350_wdt_expect_close = 42;
174 }
175 }
176 }
177 return count;
178 }
179
180 static const struct watchdog_info ident = {
181 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
182 .identity = "WM8350 Watchdog",
183 };
184
wm8350_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)185 static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
186 unsigned long arg)
187 {
188 struct wm8350 *wm8350 = get_wm8350();
189 int ret = -ENOTTY, time, i;
190 void __user *argp = (void __user *)arg;
191 int __user *p = argp;
192 u16 reg;
193
194 switch (cmd) {
195 case WDIOC_GETSUPPORT:
196 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
197 break;
198
199 case WDIOC_GETSTATUS:
200 case WDIOC_GETBOOTSTATUS:
201 ret = put_user(0, p);
202 break;
203
204 case WDIOC_SETOPTIONS:
205 {
206 int options;
207
208 if (get_user(options, p))
209 return -EFAULT;
210
211 ret = -EINVAL;
212
213 /* Setting both simultaneously means at least one must fail */
214 if (options == WDIOS_DISABLECARD)
215 ret = wm8350_wdt_start(wm8350);
216
217 if (options == WDIOS_ENABLECARD)
218 ret = wm8350_wdt_stop(wm8350);
219 break;
220 }
221
222 case WDIOC_KEEPALIVE:
223 ret = wm8350_wdt_kick(wm8350);
224 break;
225
226 case WDIOC_SETTIMEOUT:
227 ret = get_user(time, p);
228 if (ret)
229 break;
230
231 if (time == 0) {
232 if (nowayout)
233 ret = -EINVAL;
234 else
235 wm8350_wdt_stop(wm8350);
236 break;
237 }
238
239 for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
240 if (wm8350_wdt_cfgs[i].time == time)
241 break;
242 if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
243 ret = -EINVAL;
244 else
245 ret = wm8350_wdt_set_timeout(wm8350,
246 wm8350_wdt_cfgs[i].val);
247 break;
248
249 case WDIOC_GETTIMEOUT:
250 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
251 reg &= WM8350_WDOG_TO_MASK;
252 for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
253 if (wm8350_wdt_cfgs[i].val == reg)
254 break;
255 if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
256 dev_warn(wm8350->dev,
257 "Unknown watchdog configuration: %x\n", reg);
258 ret = -EINVAL;
259 } else
260 ret = put_user(wm8350_wdt_cfgs[i].time, p);
261
262 }
263
264 return ret;
265 }
266
267 static const struct file_operations wm8350_wdt_fops = {
268 .owner = THIS_MODULE,
269 .llseek = no_llseek,
270 .write = wm8350_wdt_write,
271 .unlocked_ioctl = wm8350_wdt_ioctl,
272 .open = wm8350_wdt_open,
273 .release = wm8350_wdt_release,
274 };
275
276 static struct miscdevice wm8350_wdt_miscdev = {
277 .minor = WATCHDOG_MINOR,
278 .name = "watchdog",
279 .fops = &wm8350_wdt_fops,
280 };
281
wm8350_wdt_probe(struct platform_device * pdev)282 static int __devinit wm8350_wdt_probe(struct platform_device *pdev)
283 {
284 struct wm8350 *wm8350 = platform_get_drvdata(pdev);
285
286 if (!wm8350) {
287 pr_err("No driver data supplied\n");
288 return -ENODEV;
289 }
290
291 /* Default to 4s timeout */
292 wm8350_wdt_set_timeout(wm8350, 0x05);
293
294 wm8350_wdt_miscdev.parent = &pdev->dev;
295
296 return misc_register(&wm8350_wdt_miscdev);
297 }
298
wm8350_wdt_remove(struct platform_device * pdev)299 static int __devexit wm8350_wdt_remove(struct platform_device *pdev)
300 {
301 misc_deregister(&wm8350_wdt_miscdev);
302
303 return 0;
304 }
305
306 static struct platform_driver wm8350_wdt_driver = {
307 .probe = wm8350_wdt_probe,
308 .remove = __devexit_p(wm8350_wdt_remove),
309 .driver = {
310 .name = "wm8350-wdt",
311 },
312 };
313
wm8350_wdt_init(void)314 static int __init wm8350_wdt_init(void)
315 {
316 return platform_driver_register(&wm8350_wdt_driver);
317 }
318 module_init(wm8350_wdt_init);
319
wm8350_wdt_exit(void)320 static void __exit wm8350_wdt_exit(void)
321 {
322 platform_driver_unregister(&wm8350_wdt_driver);
323 }
324 module_exit(wm8350_wdt_exit);
325
326 MODULE_AUTHOR("Mark Brown");
327 MODULE_DESCRIPTION("WM8350 Watchdog");
328 MODULE_LICENSE("GPL");
329 MODULE_ALIAS("platform:wm8350-wdt");
330