1 /*
2 * Watchdog driver for the mpcore watchdog timer
3 *
4 * (c) Copyright 2004 ARM Limited
5 *
6 * Based on the SoftDog driver:
7 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
8 * http://www.redhat.com
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
16 * warranty for any of this software. This material is provided
17 * "AS-IS" and at no charge.
18 *
19 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
20 *
21 */
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/config.h>
25 #include <linux/types.h>
26 #include <linux/miscdevice.h>
27 #include <linux/watchdog.h>
28 #include <linux/fs.h>
29 #include <linux/reboot.h>
30 #include <linux/init.h>
31 #include <linux/interrupt.h>
32 #include <linux/platform_device.h>
33
34 #include <asm/hardware/arm_twd.h>
35 #include <asm/uaccess.h>
36
37 struct mpcore_wdt {
38 unsigned long timer_alive;
39 struct device *dev;
40 void __iomem *base;
41 int irq;
42 unsigned int perturb;
43 char expect_close;
44 };
45
46 static struct platform_device *mpcore_wdt_dev;
47
48 extern unsigned int mpcore_timer_rate;
49
50 #define TIMER_MARGIN 60
51 static int mpcore_margin = TIMER_MARGIN;
52 module_param(mpcore_margin, int, 0);
53 MODULE_PARM_DESC(mpcore_margin, "MPcore timer margin in seconds. (0<mpcore_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
54
55 static int nowayout = WATCHDOG_NOWAYOUT;
56 module_param(nowayout, int, 0);
57 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
58
59 #define ONLY_TESTING 0
60 static int mpcore_noboot = ONLY_TESTING;
61 module_param(mpcore_noboot, int, 0);
62 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
63
64 /*
65 * This is the interrupt handler. Note that we only use this
66 * in testing mode, so don't actually do a reboot here.
67 */
68 static irqreturn_t mpcore_wdt_fire(int irq, void *arg, struct pt_regs *regs)
69 {
70 struct mpcore_wdt *wdt = arg;
71
72 /* Check it really was our interrupt */
73 if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
74 dev_printk(KERN_CRIT, wdt->dev, "Triggered - Reboot ignored.\n");
75
76 /* Clear the interrupt on the watchdog */
77 writel(1, wdt->base + TWD_WDOG_INTSTAT);
78
79 return IRQ_HANDLED;
80 }
81
82 return IRQ_NONE;
83 }
84
85 /*
86 * mpcore_wdt_keepalive - reload the timer
87 *
88 * Note that the spec says a DIFFERENT value must be written to the reload
89 * register each time. The "perturb" variable deals with this by adding 1
90 * to the count every other time the function is called.
91 */
92 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
93 {
94 unsigned int count;
95
96 /* Assume prescale is set to 256 */
97 count = (mpcore_timer_rate / 256) * mpcore_margin;
98
99 /* Reload the counter */
100 writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
101
102 wdt->perturb = wdt->perturb ? 0 : 1;
103 }
104
105 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
106 {
107 writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
108 writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
109 writel(0x0, wdt->base + TWD_WDOG_CONTROL);
110 }
111
112 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
113 {
114 dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
115
116 /* This loads the count register but does NOT start the count yet */
117 mpcore_wdt_keepalive(wdt);
118
119 if (mpcore_noboot) {
120 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
121 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
122 } else {
123 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
124 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
125 }
126 }
127
128 static int mpcore_wdt_set_heartbeat(int t)
129 {
130 if (t < 0x0001 || t > 0xFFFF)
131 return -EINVAL;
132
133 mpcore_margin = t;
134 return 0;
135 }
136
137 /*
138 * /dev/watchdog handling
139 */
140 static int mpcore_wdt_open(struct inode *inode, struct file *file)
141 {
142 struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
143
144 if (test_and_set_bit(0, &wdt->timer_alive))
145 return -EBUSY;
146
147 if (nowayout)
148 __module_get(THIS_MODULE);
149
150 file->private_data = wdt;
151
152 /*
153 * Activate timer
154 */
155 mpcore_wdt_start(wdt);
156
157 return nonseekable_open(inode, file);
158 }
159
160 static int mpcore_wdt_release(struct inode *inode, struct file *file)
161 {
162 struct mpcore_wdt *wdt = file->private_data;
163
164 /*
165 * Shut off the timer.
166 * Lock it in if it's a module and we set nowayout
167 */
168 if (wdt->expect_close == 42) {
169 mpcore_wdt_stop(wdt);
170 } else {
171 dev_printk(KERN_CRIT, wdt->dev, "unexpected close, not stopping watchdog!\n");
172 mpcore_wdt_keepalive(wdt);
173 }
174 clear_bit(0, &wdt->timer_alive);
175 wdt->expect_close = 0;
176 return 0;
177 }
178
179 static ssize_t mpcore_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
180 {
181 struct mpcore_wdt *wdt = file->private_data;
182
183 /*
184 * Refresh the timer.
185 */
186 if (len) {
187 if (!nowayout) {
188 size_t i;
189
190 /* In case it was set long ago */
191 wdt->expect_close = 0;
192
193 for (i = 0; i != len; i++) {
194 char c;
195
196 if (get_user(c, data + i))
197 return -EFAULT;
198 if (c == 'V')
199 wdt->expect_close = 42;
200 }
201 }
202 mpcore_wdt_keepalive(wdt);
203 }
204 return len;
205 }
206
207 static struct watchdog_info ident = {
208 .options = WDIOF_SETTIMEOUT |
209 WDIOF_KEEPALIVEPING |
210 WDIOF_MAGICCLOSE,
211 .identity = "MPcore Watchdog",
212 };
213
214 static int mpcore_wdt_ioctl(struct inode *inode, struct file *file,
215 unsigned int cmd, unsigned long arg)
216 {
217 struct mpcore_wdt *wdt = file->private_data;
218 int ret;
219 union {
220 struct watchdog_info ident;
221 int i;
222 } uarg;
223
224 if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
225 return -ENOIOCTLCMD;
226
227 if (_IOC_DIR(cmd) & _IOC_WRITE) {
228 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
229 if (ret)
230 return -EFAULT;
231 }
232
233 switch (cmd) {
234 case WDIOC_GETSUPPORT:
235 uarg.ident = ident;
236 ret = 0;
237 break;
238
239 case WDIOC_SETOPTIONS:
240 ret = -EINVAL;
241 if (uarg.i & WDIOS_DISABLECARD) {
242 mpcore_wdt_stop(wdt);
243 ret = 0;
244 }
245 if (uarg.i & WDIOS_ENABLECARD) {
246 mpcore_wdt_start(wdt);
247 ret = 0;
248 }
249 break;
250
251 case WDIOC_GETSTATUS:
252 case WDIOC_GETBOOTSTATUS:
253 uarg.i = 0;
254 ret = 0;
255 break;
256
257 case WDIOC_KEEPALIVE:
258 mpcore_wdt_keepalive(wdt);
259 ret = 0;
260 break;
261
262 case WDIOC_SETTIMEOUT:
263 ret = mpcore_wdt_set_heartbeat(uarg.i);
264 if (ret)
265 break;
266
267 mpcore_wdt_keepalive(wdt);
268 /* Fall */
269 case WDIOC_GETTIMEOUT:
270 uarg.i = mpcore_margin;
271 ret = 0;
272 break;
273
274 default:
275 return -ENOIOCTLCMD;
276 }
277
278 if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
279 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
280 if (ret)
281 ret = -EFAULT;
282 }
283 return ret;
284 }
285
286 /*
287 * System shutdown handler. Turn off the watchdog if we're
288 * restarting or halting the system.
289 */
290 static void mpcore_wdt_shutdown(struct platform_device *dev)
291 {
292 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
293
294 if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
295 mpcore_wdt_stop(wdt);
296 }
297
298 /*
299 * Kernel Interfaces
300 */
301 static struct file_operations mpcore_wdt_fops = {
302 .owner = THIS_MODULE,
303 .llseek = no_llseek,
304 .write = mpcore_wdt_write,
305 .ioctl = mpcore_wdt_ioctl,
306 .open = mpcore_wdt_open,
307 .release = mpcore_wdt_release,
308 };
309
310 static struct miscdevice mpcore_wdt_miscdev = {
311 .minor = WATCHDOG_MINOR,
312 .name = "watchdog",
313 .fops = &mpcore_wdt_fops,
314 };
315
316 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
317 {
318 struct mpcore_wdt *wdt;
319 struct resource *res;
320 int ret;
321
322 /* We only accept one device, and it must have an id of -1 */
323 if (dev->id != -1)
324 return -ENODEV;
325
326 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
327 if (!res) {
328 ret = -ENODEV;
329 goto err_out;
330 }
331
332 wdt = kmalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
333 if (!wdt) {
334 ret = -ENOMEM;
335 goto err_out;
336 }
337 memset(wdt, 0, sizeof(struct mpcore_wdt));
338
339 wdt->dev = &dev->dev;
340 wdt->irq = platform_get_irq(dev, 0);
341 if (wdt->irq < 0) {
342 ret = -ENXIO;
343 goto err_free;
344 }
345 wdt->base = ioremap(res->start, res->end - res->start + 1);
346 if (!wdt->base) {
347 ret = -ENOMEM;
348 goto err_free;
349 }
350
351 mpcore_wdt_miscdev.dev = &dev->dev;
352 ret = misc_register(&mpcore_wdt_miscdev);
353 if (ret) {
354 dev_printk(KERN_ERR, _dev, "cannot register miscdev on minor=%d (err=%d)\n",
355 WATCHDOG_MINOR, ret);
356 goto err_misc;
357 }
358
359 ret = request_irq(wdt->irq, mpcore_wdt_fire, SA_INTERRUPT, "mpcore_wdt", wdt);
360 if (ret) {
361 dev_printk(KERN_ERR, _dev, "cannot register IRQ%d for watchdog\n", wdt->irq);
362 goto err_irq;
363 }
364
365 mpcore_wdt_stop(wdt);
366 platform_set_drvdata(&dev->dev, wdt);
367 mpcore_wdt_dev = dev;
368
369 return 0;
370
371 err_irq:
372 misc_deregister(&mpcore_wdt_miscdev);
373 err_misc:
374 iounmap(wdt->base);
375 err_free:
376 kfree(wdt);
377 err_out:
378 return ret;
379 }
380
381 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
382 {
383 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
384
385 platform_set_drvdata(dev, NULL);
386
387 misc_deregister(&mpcore_wdt_miscdev);
388
389 mpcore_wdt_dev = NULL;
390
391 free_irq(wdt->irq, wdt);
392 iounmap(wdt->base);
393 kfree(wdt);
394 return 0;
395 }
396
397 static struct platform_driver mpcore_wdt_driver = {
398 .probe = mpcore_wdt_probe,
399 .remove = __devexit_p(mpcore_wdt_remove),
400 .shutdown = mpcore_wdt_shutdown,
401 .driver = {
402 .owner = THIS_MODULE,
403 .name = "mpcore_wdt",
404 },
405 };
406
407 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
408
409 static int __init mpcore_wdt_init(void)
410 {
411 /*
412 * Check that the margin value is within it's range;
413 * if not reset to the default
414 */
415 if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
416 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
417 printk(KERN_INFO "mpcore_margin value must be 0<mpcore_margin<65536, using %d\n",
418 TIMER_MARGIN);
419 }
420
421 printk(banner, mpcore_noboot, mpcore_margin, nowayout);
422
423 return platform_driver_register(&mpcore_wdt_driver);
424 }
425
426 static void __exit mpcore_wdt_exit(void)
427 {
428 platform_driver_unregister(&mpcore_wdt_driver);
429 }
430
431 module_init(mpcore_wdt_init);
432 module_exit(mpcore_wdt_exit);
433
434 MODULE_AUTHOR("ARM Limited");
435 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
436 MODULE_LICENSE("GPL");
437 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
438
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