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@lxorguk.ukuu.org.uk>,
8 * All Rights Reserved.
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/types.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
27 #include <linux/fs.h>
28 #include <linux/reboot.h>
29 #include <linux/init.h>
30 #include <linux/interrupt.h>
31 #include <linux/platform_device.h>
32 #include <linux/uaccess.h>
33 #include <linux/slab.h>
34 #include <linux/io.h>
35
36 #include <asm/smp_twd.h>
37
38 struct mpcore_wdt {
39 unsigned long timer_alive;
40 struct device *dev;
41 void __iomem *base;
42 int irq;
43 unsigned int perturb;
44 char expect_close;
45 };
46
47 static struct platform_device *mpcore_wdt_dev;
48 static DEFINE_SPINLOCK(wdt_lock);
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,
54 "MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
55 __MODULE_STRING(TIMER_MARGIN) ")");
56
57 static int nowayout = WATCHDOG_NOWAYOUT;
58 module_param(nowayout, int, 0);
59 MODULE_PARM_DESC(nowayout,
60 "Watchdog cannot be stopped once started (default="
61 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
62
63 #define ONLY_TESTING 0
64 static int mpcore_noboot = ONLY_TESTING;
65 module_param(mpcore_noboot, int, 0);
66 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
67 "set to 1 to ignore reboots, 0 to reboot (default="
68 __MODULE_STRING(ONLY_TESTING) ")");
69
70 /*
71 * This is the interrupt handler. Note that we only use this
72 * in testing mode, so don't actually do a reboot here.
73 */
mpcore_wdt_fire(int irq,void * arg)74 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
75 {
76 struct mpcore_wdt *wdt = arg;
77
78 /* Check it really was our interrupt */
79 if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
80 dev_printk(KERN_CRIT, wdt->dev,
81 "Triggered - Reboot ignored.\n");
82 /* Clear the interrupt on the watchdog */
83 writel(1, wdt->base + TWD_WDOG_INTSTAT);
84 return IRQ_HANDLED;
85 }
86 return IRQ_NONE;
87 }
88
89 /*
90 * mpcore_wdt_keepalive - reload the timer
91 *
92 * Note that the spec says a DIFFERENT value must be written to the reload
93 * register each time. The "perturb" variable deals with this by adding 1
94 * to the count every other time the function is called.
95 */
mpcore_wdt_keepalive(struct mpcore_wdt * wdt)96 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
97 {
98 unsigned long count;
99
100 spin_lock(&wdt_lock);
101 /* Assume prescale is set to 256 */
102 count = __raw_readl(wdt->base + TWD_WDOG_COUNTER);
103 count = (0xFFFFFFFFU - count) * (HZ / 5);
104 count = (count / 256) * mpcore_margin;
105
106 /* Reload the counter */
107 writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
108 wdt->perturb = wdt->perturb ? 0 : 1;
109 spin_unlock(&wdt_lock);
110 }
111
mpcore_wdt_stop(struct mpcore_wdt * wdt)112 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
113 {
114 spin_lock(&wdt_lock);
115 writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
116 writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
117 writel(0x0, wdt->base + TWD_WDOG_CONTROL);
118 spin_unlock(&wdt_lock);
119 }
120
mpcore_wdt_start(struct mpcore_wdt * wdt)121 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
122 {
123 dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
124
125 /* This loads the count register but does NOT start the count yet */
126 mpcore_wdt_keepalive(wdt);
127
128 if (mpcore_noboot) {
129 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
130 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
131 } else {
132 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
133 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
134 }
135 }
136
mpcore_wdt_set_heartbeat(int t)137 static int mpcore_wdt_set_heartbeat(int t)
138 {
139 if (t < 0x0001 || t > 0xFFFF)
140 return -EINVAL;
141
142 mpcore_margin = t;
143 return 0;
144 }
145
146 /*
147 * /dev/watchdog handling
148 */
mpcore_wdt_open(struct inode * inode,struct file * file)149 static int mpcore_wdt_open(struct inode *inode, struct file *file)
150 {
151 struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
152
153 if (test_and_set_bit(0, &wdt->timer_alive))
154 return -EBUSY;
155
156 if (nowayout)
157 __module_get(THIS_MODULE);
158
159 file->private_data = wdt;
160
161 /*
162 * Activate timer
163 */
164 mpcore_wdt_start(wdt);
165
166 return nonseekable_open(inode, file);
167 }
168
mpcore_wdt_release(struct inode * inode,struct file * file)169 static int mpcore_wdt_release(struct inode *inode, struct file *file)
170 {
171 struct mpcore_wdt *wdt = file->private_data;
172
173 /*
174 * Shut off the timer.
175 * Lock it in if it's a module and we set nowayout
176 */
177 if (wdt->expect_close == 42)
178 mpcore_wdt_stop(wdt);
179 else {
180 dev_printk(KERN_CRIT, wdt->dev,
181 "unexpected close, not stopping watchdog!\n");
182 mpcore_wdt_keepalive(wdt);
183 }
184 clear_bit(0, &wdt->timer_alive);
185 wdt->expect_close = 0;
186 return 0;
187 }
188
mpcore_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)189 static ssize_t mpcore_wdt_write(struct file *file, const char *data,
190 size_t len, loff_t *ppos)
191 {
192 struct mpcore_wdt *wdt = file->private_data;
193
194 /*
195 * Refresh the timer.
196 */
197 if (len) {
198 if (!nowayout) {
199 size_t i;
200
201 /* In case it was set long ago */
202 wdt->expect_close = 0;
203
204 for (i = 0; i != len; i++) {
205 char c;
206
207 if (get_user(c, data + i))
208 return -EFAULT;
209 if (c == 'V')
210 wdt->expect_close = 42;
211 }
212 }
213 mpcore_wdt_keepalive(wdt);
214 }
215 return len;
216 }
217
218 static const struct watchdog_info ident = {
219 .options = WDIOF_SETTIMEOUT |
220 WDIOF_KEEPALIVEPING |
221 WDIOF_MAGICCLOSE,
222 .identity = "MPcore Watchdog",
223 };
224
mpcore_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)225 static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
226 unsigned long arg)
227 {
228 struct mpcore_wdt *wdt = file->private_data;
229 int ret;
230 union {
231 struct watchdog_info ident;
232 int i;
233 } uarg;
234
235 if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
236 return -ENOTTY;
237
238 if (_IOC_DIR(cmd) & _IOC_WRITE) {
239 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
240 if (ret)
241 return -EFAULT;
242 }
243
244 switch (cmd) {
245 case WDIOC_GETSUPPORT:
246 uarg.ident = ident;
247 ret = 0;
248 break;
249
250 case WDIOC_GETSTATUS:
251 case WDIOC_GETBOOTSTATUS:
252 uarg.i = 0;
253 ret = 0;
254 break;
255
256 case WDIOC_SETOPTIONS:
257 ret = -EINVAL;
258 if (uarg.i & WDIOS_DISABLECARD) {
259 mpcore_wdt_stop(wdt);
260 ret = 0;
261 }
262 if (uarg.i & WDIOS_ENABLECARD) {
263 mpcore_wdt_start(wdt);
264 ret = 0;
265 }
266 break;
267
268 case WDIOC_KEEPALIVE:
269 mpcore_wdt_keepalive(wdt);
270 ret = 0;
271 break;
272
273 case WDIOC_SETTIMEOUT:
274 ret = mpcore_wdt_set_heartbeat(uarg.i);
275 if (ret)
276 break;
277
278 mpcore_wdt_keepalive(wdt);
279 /* Fall */
280 case WDIOC_GETTIMEOUT:
281 uarg.i = mpcore_margin;
282 ret = 0;
283 break;
284
285 default:
286 return -ENOTTY;
287 }
288
289 if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
290 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
291 if (ret)
292 ret = -EFAULT;
293 }
294 return ret;
295 }
296
297 /*
298 * System shutdown handler. Turn off the watchdog if we're
299 * restarting or halting the system.
300 */
mpcore_wdt_shutdown(struct platform_device * dev)301 static void mpcore_wdt_shutdown(struct platform_device *dev)
302 {
303 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
304
305 if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
306 mpcore_wdt_stop(wdt);
307 }
308
309 /*
310 * Kernel Interfaces
311 */
312 static const struct file_operations mpcore_wdt_fops = {
313 .owner = THIS_MODULE,
314 .llseek = no_llseek,
315 .write = mpcore_wdt_write,
316 .unlocked_ioctl = mpcore_wdt_ioctl,
317 .open = mpcore_wdt_open,
318 .release = mpcore_wdt_release,
319 };
320
321 static struct miscdevice mpcore_wdt_miscdev = {
322 .minor = WATCHDOG_MINOR,
323 .name = "watchdog",
324 .fops = &mpcore_wdt_fops,
325 };
326
mpcore_wdt_probe(struct platform_device * dev)327 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
328 {
329 struct mpcore_wdt *wdt;
330 struct resource *res;
331 int ret;
332
333 /* We only accept one device, and it must have an id of -1 */
334 if (dev->id != -1)
335 return -ENODEV;
336
337 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
338 if (!res) {
339 ret = -ENODEV;
340 goto err_out;
341 }
342
343 wdt = kzalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
344 if (!wdt) {
345 ret = -ENOMEM;
346 goto err_out;
347 }
348
349 wdt->dev = &dev->dev;
350 wdt->irq = platform_get_irq(dev, 0);
351 if (wdt->irq < 0) {
352 ret = -ENXIO;
353 goto err_free;
354 }
355 wdt->base = ioremap(res->start, resource_size(res));
356 if (!wdt->base) {
357 ret = -ENOMEM;
358 goto err_free;
359 }
360
361 mpcore_wdt_miscdev.parent = &dev->dev;
362 ret = misc_register(&mpcore_wdt_miscdev);
363 if (ret) {
364 dev_printk(KERN_ERR, wdt->dev,
365 "cannot register miscdev on minor=%d (err=%d)\n",
366 WATCHDOG_MINOR, ret);
367 goto err_misc;
368 }
369
370 ret = request_irq(wdt->irq, mpcore_wdt_fire, 0, "mpcore_wdt", wdt);
371 if (ret) {
372 dev_printk(KERN_ERR, wdt->dev,
373 "cannot register IRQ%d for watchdog\n", wdt->irq);
374 goto err_irq;
375 }
376
377 mpcore_wdt_stop(wdt);
378 platform_set_drvdata(dev, wdt);
379 mpcore_wdt_dev = dev;
380
381 return 0;
382
383 err_irq:
384 misc_deregister(&mpcore_wdt_miscdev);
385 err_misc:
386 iounmap(wdt->base);
387 err_free:
388 kfree(wdt);
389 err_out:
390 return ret;
391 }
392
mpcore_wdt_remove(struct platform_device * dev)393 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
394 {
395 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
396
397 platform_set_drvdata(dev, NULL);
398
399 misc_deregister(&mpcore_wdt_miscdev);
400
401 mpcore_wdt_dev = NULL;
402
403 free_irq(wdt->irq, wdt);
404 iounmap(wdt->base);
405 kfree(wdt);
406 return 0;
407 }
408
409 #ifdef CONFIG_PM
mpcore_wdt_suspend(struct platform_device * dev,pm_message_t msg)410 static int mpcore_wdt_suspend(struct platform_device *dev, pm_message_t msg)
411 {
412 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
413 mpcore_wdt_stop(wdt); /* Turn the WDT off */
414 return 0;
415 }
416
mpcore_wdt_resume(struct platform_device * dev)417 static int mpcore_wdt_resume(struct platform_device *dev)
418 {
419 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
420 /* re-activate timer */
421 if (test_bit(0, &wdt->timer_alive))
422 mpcore_wdt_start(wdt);
423 return 0;
424 }
425 #else
426 #define mpcore_wdt_suspend NULL
427 #define mpcore_wdt_resume NULL
428 #endif
429
430 /* work with hotplug and coldplug */
431 MODULE_ALIAS("platform:mpcore_wdt");
432
433 static struct platform_driver mpcore_wdt_driver = {
434 .probe = mpcore_wdt_probe,
435 .remove = __devexit_p(mpcore_wdt_remove),
436 .suspend = mpcore_wdt_suspend,
437 .resume = mpcore_wdt_resume,
438 .shutdown = mpcore_wdt_shutdown,
439 .driver = {
440 .owner = THIS_MODULE,
441 .name = "mpcore_wdt",
442 },
443 };
444
445 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. "
446 "mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
447
mpcore_wdt_init(void)448 static int __init mpcore_wdt_init(void)
449 {
450 /*
451 * Check that the margin value is within it's range;
452 * if not reset to the default
453 */
454 if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
455 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
456 printk(KERN_INFO "mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
457 TIMER_MARGIN);
458 }
459
460 printk(banner, mpcore_noboot, mpcore_margin, nowayout);
461
462 return platform_driver_register(&mpcore_wdt_driver);
463 }
464
mpcore_wdt_exit(void)465 static void __exit mpcore_wdt_exit(void)
466 {
467 platform_driver_unregister(&mpcore_wdt_driver);
468 }
469
470 module_init(mpcore_wdt_init);
471 module_exit(mpcore_wdt_exit);
472
473 MODULE_AUTHOR("ARM Limited");
474 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
475 MODULE_LICENSE("GPL");
476 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
477