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
28 #define KS8695_TMR_OFFSET (0xF0000 + 0xE400)
29 #define KS8695_TMR_VA (KS8695_IO_VA + KS8695_TMR_OFFSET)
30
31 /*
32 * Timer registers
33 */
34 #define KS8695_TMCON (0x00) /* Timer Control Register */
35 #define KS8695_T0TC (0x08) /* Timer 0 Timeout Count Register */
36 #define TMCON_T0EN (1 << 0) /* Timer 0 Enable */
37
38 /* Timer0 Timeout Counter Register */
39 #define T0TC_WATCHDOG (0xff) /* Enable watchdog mode */
40
41 #define WDT_DEFAULT_TIME 5 /* seconds */
42 #define WDT_MAX_TIME 171 /* seconds */
43
44 static int wdt_time = WDT_DEFAULT_TIME;
45 static bool nowayout = WATCHDOG_NOWAYOUT;
46
47 module_param(wdt_time, int, 0);
48 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
49 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
50
51 #ifdef CONFIG_WATCHDOG_NOWAYOUT
52 module_param(nowayout, bool, 0);
53 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
54 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
55 #endif
56
57
58 static unsigned long ks8695wdt_busy;
59 static DEFINE_SPINLOCK(ks8695_lock);
60
61 /* ......................................................................... */
62
63 /*
64 * Disable the watchdog.
65 */
ks8695_wdt_stop(void)66 static inline void ks8695_wdt_stop(void)
67 {
68 unsigned long tmcon;
69
70 spin_lock(&ks8695_lock);
71 /* disable timer0 */
72 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
73 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
74 spin_unlock(&ks8695_lock);
75 }
76
77 /*
78 * Enable and reset the watchdog.
79 */
ks8695_wdt_start(void)80 static inline void ks8695_wdt_start(void)
81 {
82 unsigned long tmcon;
83 unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
84
85 spin_lock(&ks8695_lock);
86 /* disable timer0 */
87 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
88 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
89
90 /* program timer0 */
91 __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
92
93 /* re-enable timer0 */
94 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
95 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
96 spin_unlock(&ks8695_lock);
97 }
98
99 /*
100 * Reload the watchdog timer. (ie, pat the watchdog)
101 */
ks8695_wdt_reload(void)102 static inline void ks8695_wdt_reload(void)
103 {
104 unsigned long tmcon;
105
106 spin_lock(&ks8695_lock);
107 /* disable, then re-enable timer0 */
108 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
109 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
110 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
111 spin_unlock(&ks8695_lock);
112 }
113
114 /*
115 * Change the watchdog time interval.
116 */
ks8695_wdt_settimeout(int new_time)117 static int ks8695_wdt_settimeout(int new_time)
118 {
119 /*
120 * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
121 *
122 * Since WDV is a 16-bit counter, the maximum period is
123 * 65536 / 0.256 = 256 seconds.
124 */
125 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
126 return -EINVAL;
127
128 /* Set new watchdog time. It will be used when
129 ks8695_wdt_start() is called. */
130 wdt_time = new_time;
131 return 0;
132 }
133
134 /* ......................................................................... */
135
136 /*
137 * Watchdog device is opened, and watchdog starts running.
138 */
ks8695_wdt_open(struct inode * inode,struct file * file)139 static int ks8695_wdt_open(struct inode *inode, struct file *file)
140 {
141 if (test_and_set_bit(0, &ks8695wdt_busy))
142 return -EBUSY;
143
144 ks8695_wdt_start();
145 return nonseekable_open(inode, file);
146 }
147
148 /*
149 * Close the watchdog device.
150 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
151 * disabled.
152 */
ks8695_wdt_close(struct inode * inode,struct file * file)153 static int ks8695_wdt_close(struct inode *inode, struct file *file)
154 {
155 /* Disable the watchdog when file is closed */
156 if (!nowayout)
157 ks8695_wdt_stop();
158 clear_bit(0, &ks8695wdt_busy);
159 return 0;
160 }
161
162 static const struct watchdog_info ks8695_wdt_info = {
163 .identity = "ks8695 watchdog",
164 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
165 };
166
167 /*
168 * Handle commands from user-space.
169 */
ks8695_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)170 static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
171 unsigned long arg)
172 {
173 void __user *argp = (void __user *)arg;
174 int __user *p = argp;
175 int new_value;
176
177 switch (cmd) {
178 case WDIOC_GETSUPPORT:
179 return copy_to_user(argp, &ks8695_wdt_info,
180 sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
181 case WDIOC_GETSTATUS:
182 case WDIOC_GETBOOTSTATUS:
183 return put_user(0, p);
184 case WDIOC_SETOPTIONS:
185 if (get_user(new_value, p))
186 return -EFAULT;
187 if (new_value & WDIOS_DISABLECARD)
188 ks8695_wdt_stop();
189 if (new_value & WDIOS_ENABLECARD)
190 ks8695_wdt_start();
191 return 0;
192 case WDIOC_KEEPALIVE:
193 ks8695_wdt_reload(); /* pat the watchdog */
194 return 0;
195 case WDIOC_SETTIMEOUT:
196 if (get_user(new_value, p))
197 return -EFAULT;
198 if (ks8695_wdt_settimeout(new_value))
199 return -EINVAL;
200 /* Enable new time value */
201 ks8695_wdt_start();
202 /* Return current value */
203 return put_user(wdt_time, p);
204 case WDIOC_GETTIMEOUT:
205 return put_user(wdt_time, p);
206 default:
207 return -ENOTTY;
208 }
209 }
210
211 /*
212 * Pat the watchdog whenever device is written to.
213 */
ks8695_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)214 static ssize_t ks8695_wdt_write(struct file *file, const char *data,
215 size_t len, loff_t *ppos)
216 {
217 ks8695_wdt_reload(); /* pat the watchdog */
218 return len;
219 }
220
221 /* ......................................................................... */
222
223 static const struct file_operations ks8695wdt_fops = {
224 .owner = THIS_MODULE,
225 .llseek = no_llseek,
226 .unlocked_ioctl = ks8695_wdt_ioctl,
227 .open = ks8695_wdt_open,
228 .release = ks8695_wdt_close,
229 .write = ks8695_wdt_write,
230 };
231
232 static struct miscdevice ks8695wdt_miscdev = {
233 .minor = WATCHDOG_MINOR,
234 .name = "watchdog",
235 .fops = &ks8695wdt_fops,
236 };
237
ks8695wdt_probe(struct platform_device * pdev)238 static int ks8695wdt_probe(struct platform_device *pdev)
239 {
240 int res;
241
242 if (ks8695wdt_miscdev.parent)
243 return -EBUSY;
244 ks8695wdt_miscdev.parent = &pdev->dev;
245
246 res = misc_register(&ks8695wdt_miscdev);
247 if (res)
248 return res;
249
250 pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)\n",
251 wdt_time, nowayout ? ", nowayout" : "");
252 return 0;
253 }
254
ks8695wdt_remove(struct platform_device * pdev)255 static int ks8695wdt_remove(struct platform_device *pdev)
256 {
257 misc_deregister(&ks8695wdt_miscdev);
258 ks8695wdt_miscdev.parent = NULL;
259
260 return 0;
261 }
262
ks8695wdt_shutdown(struct platform_device * pdev)263 static void ks8695wdt_shutdown(struct platform_device *pdev)
264 {
265 ks8695_wdt_stop();
266 }
267
268 #ifdef CONFIG_PM
269
ks8695wdt_suspend(struct platform_device * pdev,pm_message_t message)270 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
271 {
272 ks8695_wdt_stop();
273 return 0;
274 }
275
ks8695wdt_resume(struct platform_device * pdev)276 static int ks8695wdt_resume(struct platform_device *pdev)
277 {
278 if (ks8695wdt_busy)
279 ks8695_wdt_start();
280 return 0;
281 }
282
283 #else
284 #define ks8695wdt_suspend NULL
285 #define ks8695wdt_resume NULL
286 #endif
287
288 static struct platform_driver ks8695wdt_driver = {
289 .probe = ks8695wdt_probe,
290 .remove = ks8695wdt_remove,
291 .shutdown = ks8695wdt_shutdown,
292 .suspend = ks8695wdt_suspend,
293 .resume = ks8695wdt_resume,
294 .driver = {
295 .name = "ks8695_wdt",
296 },
297 };
298
ks8695_wdt_init(void)299 static int __init ks8695_wdt_init(void)
300 {
301 /* Check that the heartbeat value is within range;
302 if not reset to the default */
303 if (ks8695_wdt_settimeout(wdt_time)) {
304 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
305 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
306 ", using %d\n", wdt_time, WDT_MAX_TIME);
307 }
308 return platform_driver_register(&ks8695wdt_driver);
309 }
310
ks8695_wdt_exit(void)311 static void __exit ks8695_wdt_exit(void)
312 {
313 platform_driver_unregister(&ks8695wdt_driver);
314 }
315
316 module_init(ks8695_wdt_init);
317 module_exit(ks8695_wdt_exit);
318
319 MODULE_AUTHOR("Andrew Victor");
320 MODULE_DESCRIPTION("Watchdog driver for KS8695");
321 MODULE_LICENSE("GPL");
322 MODULE_ALIAS("platform:ks8695_wdt");
323
