1 /*
2 * Watchdog driver for Kendin/Micrel KS8695.
3 *
4 * (C) 2007 Andrew Victor
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/bitops.h>
14 #include <linux/errno.h>
15 #include <linux/fs.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/miscdevice.h>
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/platform_device.h>
22 #include <linux/types.h>
23 #include <linux/watchdog.h>
24 #include <linux/io.h>
25 #include <linux/uaccess.h>
26 #include <mach/hardware.h>
27 #include <mach/regs-timer.h>
28
29 #define WDT_DEFAULT_TIME 5 /* seconds */
30 #define WDT_MAX_TIME 171 /* seconds */
31
32 static int wdt_time = WDT_DEFAULT_TIME;
33 static bool nowayout = WATCHDOG_NOWAYOUT;
34
35 module_param(wdt_time, int, 0);
36 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
37 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
38
39 #ifdef CONFIG_WATCHDOG_NOWAYOUT
40 module_param(nowayout, bool, 0);
41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
42 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
43 #endif
44
45
46 static unsigned long ks8695wdt_busy;
47 static DEFINE_SPINLOCK(ks8695_lock);
48
49 /* ......................................................................... */
50
51 /*
52 * Disable the watchdog.
53 */
ks8695_wdt_stop(void)54 static inline void ks8695_wdt_stop(void)
55 {
56 unsigned long tmcon;
57
58 spin_lock(&ks8695_lock);
59 /* disable timer0 */
60 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
61 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
62 spin_unlock(&ks8695_lock);
63 }
64
65 /*
66 * Enable and reset the watchdog.
67 */
ks8695_wdt_start(void)68 static inline void ks8695_wdt_start(void)
69 {
70 unsigned long tmcon;
71 unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
72
73 spin_lock(&ks8695_lock);
74 /* disable timer0 */
75 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
76 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
77
78 /* program timer0 */
79 __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
80
81 /* re-enable timer0 */
82 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
83 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
84 spin_unlock(&ks8695_lock);
85 }
86
87 /*
88 * Reload the watchdog timer. (ie, pat the watchdog)
89 */
ks8695_wdt_reload(void)90 static inline void ks8695_wdt_reload(void)
91 {
92 unsigned long tmcon;
93
94 spin_lock(&ks8695_lock);
95 /* disable, then re-enable timer0 */
96 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
97 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
98 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
99 spin_unlock(&ks8695_lock);
100 }
101
102 /*
103 * Change the watchdog time interval.
104 */
ks8695_wdt_settimeout(int new_time)105 static int ks8695_wdt_settimeout(int new_time)
106 {
107 /*
108 * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
109 *
110 * Since WDV is a 16-bit counter, the maximum period is
111 * 65536 / 0.256 = 256 seconds.
112 */
113 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
114 return -EINVAL;
115
116 /* Set new watchdog time. It will be used when
117 ks8695_wdt_start() is called. */
118 wdt_time = new_time;
119 return 0;
120 }
121
122 /* ......................................................................... */
123
124 /*
125 * Watchdog device is opened, and watchdog starts running.
126 */
ks8695_wdt_open(struct inode * inode,struct file * file)127 static int ks8695_wdt_open(struct inode *inode, struct file *file)
128 {
129 if (test_and_set_bit(0, &ks8695wdt_busy))
130 return -EBUSY;
131
132 ks8695_wdt_start();
133 return nonseekable_open(inode, file);
134 }
135
136 /*
137 * Close the watchdog device.
138 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
139 * disabled.
140 */
ks8695_wdt_close(struct inode * inode,struct file * file)141 static int ks8695_wdt_close(struct inode *inode, struct file *file)
142 {
143 /* Disable the watchdog when file is closed */
144 if (!nowayout)
145 ks8695_wdt_stop();
146 clear_bit(0, &ks8695wdt_busy);
147 return 0;
148 }
149
150 static const struct watchdog_info ks8695_wdt_info = {
151 .identity = "ks8695 watchdog",
152 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
153 };
154
155 /*
156 * Handle commands from user-space.
157 */
ks8695_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)158 static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
159 unsigned long arg)
160 {
161 void __user *argp = (void __user *)arg;
162 int __user *p = argp;
163 int new_value;
164
165 switch (cmd) {
166 case WDIOC_GETSUPPORT:
167 return copy_to_user(argp, &ks8695_wdt_info,
168 sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
169 case WDIOC_GETSTATUS:
170 case WDIOC_GETBOOTSTATUS:
171 return put_user(0, p);
172 case WDIOC_SETOPTIONS:
173 if (get_user(new_value, p))
174 return -EFAULT;
175 if (new_value & WDIOS_DISABLECARD)
176 ks8695_wdt_stop();
177 if (new_value & WDIOS_ENABLECARD)
178 ks8695_wdt_start();
179 return 0;
180 case WDIOC_KEEPALIVE:
181 ks8695_wdt_reload(); /* pat the watchdog */
182 return 0;
183 case WDIOC_SETTIMEOUT:
184 if (get_user(new_value, p))
185 return -EFAULT;
186 if (ks8695_wdt_settimeout(new_value))
187 return -EINVAL;
188 /* Enable new time value */
189 ks8695_wdt_start();
190 /* Return current value */
191 return put_user(wdt_time, p);
192 case WDIOC_GETTIMEOUT:
193 return put_user(wdt_time, p);
194 default:
195 return -ENOTTY;
196 }
197 }
198
199 /*
200 * Pat the watchdog whenever device is written to.
201 */
ks8695_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)202 static ssize_t ks8695_wdt_write(struct file *file, const char *data,
203 size_t len, loff_t *ppos)
204 {
205 ks8695_wdt_reload(); /* pat the watchdog */
206 return len;
207 }
208
209 /* ......................................................................... */
210
211 static const struct file_operations ks8695wdt_fops = {
212 .owner = THIS_MODULE,
213 .llseek = no_llseek,
214 .unlocked_ioctl = ks8695_wdt_ioctl,
215 .open = ks8695_wdt_open,
216 .release = ks8695_wdt_close,
217 .write = ks8695_wdt_write,
218 };
219
220 static struct miscdevice ks8695wdt_miscdev = {
221 .minor = WATCHDOG_MINOR,
222 .name = "watchdog",
223 .fops = &ks8695wdt_fops,
224 };
225
ks8695wdt_probe(struct platform_device * pdev)226 static int __devinit ks8695wdt_probe(struct platform_device *pdev)
227 {
228 int res;
229
230 if (ks8695wdt_miscdev.parent)
231 return -EBUSY;
232 ks8695wdt_miscdev.parent = &pdev->dev;
233
234 res = misc_register(&ks8695wdt_miscdev);
235 if (res)
236 return res;
237
238 pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)\n",
239 wdt_time, nowayout ? ", nowayout" : "");
240 return 0;
241 }
242
ks8695wdt_remove(struct platform_device * pdev)243 static int __devexit ks8695wdt_remove(struct platform_device *pdev)
244 {
245 int res;
246
247 res = misc_deregister(&ks8695wdt_miscdev);
248 if (!res)
249 ks8695wdt_miscdev.parent = NULL;
250
251 return res;
252 }
253
ks8695wdt_shutdown(struct platform_device * pdev)254 static void ks8695wdt_shutdown(struct platform_device *pdev)
255 {
256 ks8695_wdt_stop();
257 }
258
259 #ifdef CONFIG_PM
260
ks8695wdt_suspend(struct platform_device * pdev,pm_message_t message)261 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
262 {
263 ks8695_wdt_stop();
264 return 0;
265 }
266
ks8695wdt_resume(struct platform_device * pdev)267 static int ks8695wdt_resume(struct platform_device *pdev)
268 {
269 if (ks8695wdt_busy)
270 ks8695_wdt_start();
271 return 0;
272 }
273
274 #else
275 #define ks8695wdt_suspend NULL
276 #define ks8695wdt_resume NULL
277 #endif
278
279 static struct platform_driver ks8695wdt_driver = {
280 .probe = ks8695wdt_probe,
281 .remove = __devexit_p(ks8695wdt_remove),
282 .shutdown = ks8695wdt_shutdown,
283 .suspend = ks8695wdt_suspend,
284 .resume = ks8695wdt_resume,
285 .driver = {
286 .name = "ks8695_wdt",
287 .owner = THIS_MODULE,
288 },
289 };
290
ks8695_wdt_init(void)291 static int __init ks8695_wdt_init(void)
292 {
293 /* Check that the heartbeat value is within range;
294 if not reset to the default */
295 if (ks8695_wdt_settimeout(wdt_time)) {
296 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
297 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
298 ", using %d\n", wdt_time, WDT_MAX_TIME);
299 }
300 return platform_driver_register(&ks8695wdt_driver);
301 }
302
ks8695_wdt_exit(void)303 static void __exit ks8695_wdt_exit(void)
304 {
305 platform_driver_unregister(&ks8695wdt_driver);
306 }
307
308 module_init(ks8695_wdt_init);
309 module_exit(ks8695_wdt_exit);
310
311 MODULE_AUTHOR("Andrew Victor");
312 MODULE_DESCRIPTION("Watchdog driver for KS8695");
313 MODULE_LICENSE("GPL");
314 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
315 MODULE_ALIAS("platform:ks8695_wdt");
316