Merge branch 'for-linus' of git://www.atmel.no/~hskinnemoen/linux/kernel/avr32
[linux-2.6] / drivers / char / watchdog / mpcore_wdt.c
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/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
33 #include <asm/hardware/arm_twd.h>
34 #include <asm/uaccess.h>
35
36 struct mpcore_wdt {
37         unsigned long   timer_alive;
38         struct device   *dev;
39         void __iomem    *base;
40         int             irq;
41         unsigned int    perturb;
42         char            expect_close;
43 };
44
45 static struct platform_device *mpcore_wdt_dev;
46
47 extern unsigned int mpcore_timer_rate;
48
49 #define TIMER_MARGIN    60
50 static int mpcore_margin = TIMER_MARGIN;
51 module_param(mpcore_margin, int, 0);
52 MODULE_PARM_DESC(mpcore_margin, "MPcore timer margin in seconds. (0<mpcore_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
53
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 module_param(nowayout, int, 0);
56 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
57
58 #define ONLY_TESTING    0
59 static int mpcore_noboot = ONLY_TESTING;
60 module_param(mpcore_noboot, int, 0);
61 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
62
63 /*
64  *      This is the interrupt handler.  Note that we only use this
65  *      in testing mode, so don't actually do a reboot here.
66  */
67 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
68 {
69         struct mpcore_wdt *wdt = arg;
70
71         /* Check it really was our interrupt */
72         if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
73                 dev_printk(KERN_CRIT, wdt->dev, "Triggered - Reboot ignored.\n");
74
75                 /* Clear the interrupt on the watchdog */
76                 writel(1, wdt->base + TWD_WDOG_INTSTAT);
77
78                 return IRQ_HANDLED;
79         }
80
81         return IRQ_NONE;
82 }
83
84 /*
85  *      mpcore_wdt_keepalive - reload the timer
86  *
87  *      Note that the spec says a DIFFERENT value must be written to the reload
88  *      register each time.  The "perturb" variable deals with this by adding 1
89  *      to the count every other time the function is called.
90  */
91 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
92 {
93         unsigned int count;
94
95         /* Assume prescale is set to 256 */
96         count = (mpcore_timer_rate / 256) * mpcore_margin;
97
98         /* Reload the counter */
99         writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
100
101         wdt->perturb = wdt->perturb ? 0 : 1;
102 }
103
104 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
105 {
106         writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
107         writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
108         writel(0x0, wdt->base + TWD_WDOG_CONTROL);
109 }
110
111 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
112 {
113         dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
114
115         /* This loads the count register but does NOT start the count yet */
116         mpcore_wdt_keepalive(wdt);
117
118         if (mpcore_noboot) {
119                 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
120                 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
121         } else {
122                 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
123                 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
124         }
125 }
126
127 static int mpcore_wdt_set_heartbeat(int t)
128 {
129         if (t < 0x0001 || t > 0xFFFF)
130                 return -EINVAL;
131
132         mpcore_margin = t;
133         return 0;
134 }
135
136 /*
137  *      /dev/watchdog handling
138  */
139 static int mpcore_wdt_open(struct inode *inode, struct file *file)
140 {
141         struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
142
143         if (test_and_set_bit(0, &wdt->timer_alive))
144                 return -EBUSY;
145
146         if (nowayout)
147                 __module_get(THIS_MODULE);
148
149         file->private_data = wdt;
150
151         /*
152          *      Activate timer
153          */
154         mpcore_wdt_start(wdt);
155
156         return nonseekable_open(inode, file);
157 }
158
159 static int mpcore_wdt_release(struct inode *inode, struct file *file)
160 {
161         struct mpcore_wdt *wdt = file->private_data;
162
163         /*
164          *      Shut off the timer.
165          *      Lock it in if it's a module and we set nowayout
166          */
167         if (wdt->expect_close == 42) {
168                 mpcore_wdt_stop(wdt);
169         } else {
170                 dev_printk(KERN_CRIT, wdt->dev, "unexpected close, not stopping watchdog!\n");
171                 mpcore_wdt_keepalive(wdt);
172         }
173         clear_bit(0, &wdt->timer_alive);
174         wdt->expect_close = 0;
175         return 0;
176 }
177
178 static ssize_t mpcore_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
179 {
180         struct mpcore_wdt *wdt = file->private_data;
181
182         /*
183          *      Refresh the timer.
184          */
185         if (len) {
186                 if (!nowayout) {
187                         size_t i;
188
189                         /* In case it was set long ago */
190                         wdt->expect_close = 0;
191
192                         for (i = 0; i != len; i++) {
193                                 char c;
194
195                                 if (get_user(c, data + i))
196                                         return -EFAULT;
197                                 if (c == 'V')
198                                         wdt->expect_close = 42;
199                         }
200                 }
201                 mpcore_wdt_keepalive(wdt);
202         }
203         return len;
204 }
205
206 static struct watchdog_info ident = {
207         .options                = WDIOF_SETTIMEOUT |
208                                   WDIOF_KEEPALIVEPING |
209                                   WDIOF_MAGICCLOSE,
210         .identity               = "MPcore Watchdog",
211 };
212
213 static int mpcore_wdt_ioctl(struct inode *inode, struct file *file,
214                              unsigned int cmd, unsigned long arg)
215 {
216         struct mpcore_wdt *wdt = file->private_data;
217         int ret;
218         union {
219                 struct watchdog_info ident;
220                 int i;
221         } uarg;
222
223         if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
224                 return -ENOTTY;
225
226         if (_IOC_DIR(cmd) & _IOC_WRITE) {
227                 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
228                 if (ret)
229                         return -EFAULT;
230         }
231
232         switch (cmd) {
233         case WDIOC_GETSUPPORT:
234                 uarg.ident = ident;
235                 ret = 0;
236                 break;
237
238         case WDIOC_SETOPTIONS:
239                 ret = -EINVAL;
240                 if (uarg.i & WDIOS_DISABLECARD) {
241                         mpcore_wdt_stop(wdt);
242                         ret = 0;
243                 }
244                 if (uarg.i & WDIOS_ENABLECARD) {
245                         mpcore_wdt_start(wdt);
246                         ret = 0;
247                 }
248                 break;
249
250         case WDIOC_GETSTATUS:
251         case WDIOC_GETBOOTSTATUS:
252                 uarg.i = 0;
253                 ret = 0;
254                 break;
255
256         case WDIOC_KEEPALIVE:
257                 mpcore_wdt_keepalive(wdt);
258                 ret = 0;
259                 break;
260
261         case WDIOC_SETTIMEOUT:
262                 ret = mpcore_wdt_set_heartbeat(uarg.i);
263                 if (ret)
264                         break;
265
266                 mpcore_wdt_keepalive(wdt);
267                 /* Fall */
268         case WDIOC_GETTIMEOUT:
269                 uarg.i = mpcore_margin;
270                 ret = 0;
271                 break;
272
273         default:
274                 return -ENOTTY;
275         }
276
277         if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
278                 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
279                 if (ret)
280                         ret = -EFAULT;
281         }
282         return ret;
283 }
284
285 /*
286  *      System shutdown handler.  Turn off the watchdog if we're
287  *      restarting or halting the system.
288  */
289 static void mpcore_wdt_shutdown(struct platform_device *dev)
290 {
291         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
292
293         if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
294                 mpcore_wdt_stop(wdt);
295 }
296
297 /*
298  *      Kernel Interfaces
299  */
300 static const struct file_operations mpcore_wdt_fops = {
301         .owner          = THIS_MODULE,
302         .llseek         = no_llseek,
303         .write          = mpcore_wdt_write,
304         .ioctl          = mpcore_wdt_ioctl,
305         .open           = mpcore_wdt_open,
306         .release        = mpcore_wdt_release,
307 };
308
309 static struct miscdevice mpcore_wdt_miscdev = {
310         .minor          = WATCHDOG_MINOR,
311         .name           = "watchdog",
312         .fops           = &mpcore_wdt_fops,
313 };
314
315 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
316 {
317         struct mpcore_wdt *wdt;
318         struct resource *res;
319         int ret;
320
321         /* We only accept one device, and it must have an id of -1 */
322         if (dev->id != -1)
323                 return -ENODEV;
324
325         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
326         if (!res) {
327                 ret = -ENODEV;
328                 goto err_out;
329         }
330
331         wdt = kmalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
332         if (!wdt) {
333                 ret = -ENOMEM;
334                 goto err_out;
335         }
336         memset(wdt, 0, sizeof(struct mpcore_wdt));
337
338         wdt->dev = &dev->dev;
339         wdt->irq = platform_get_irq(dev, 0);
340         if (wdt->irq < 0) {
341                 ret = -ENXIO;
342                 goto err_free;
343         }
344         wdt->base = ioremap(res->start, res->end - res->start + 1);
345         if (!wdt->base) {
346                 ret = -ENOMEM;
347                 goto err_free;
348         }
349
350         mpcore_wdt_miscdev.dev = &dev->dev;
351         ret = misc_register(&mpcore_wdt_miscdev);
352         if (ret) {
353                 dev_printk(KERN_ERR, _dev, "cannot register miscdev on minor=%d (err=%d)\n",
354                            WATCHDOG_MINOR, ret);
355                 goto err_misc;
356         }
357
358         ret = request_irq(wdt->irq, mpcore_wdt_fire, IRQF_DISABLED, "mpcore_wdt", wdt);
359         if (ret) {
360                 dev_printk(KERN_ERR, _dev, "cannot register IRQ%d for watchdog\n", wdt->irq);
361                 goto err_irq;
362         }
363
364         mpcore_wdt_stop(wdt);
365         platform_set_drvdata(&dev->dev, wdt);
366         mpcore_wdt_dev = dev;
367
368         return 0;
369
370  err_irq:
371         misc_deregister(&mpcore_wdt_miscdev);
372  err_misc:
373         iounmap(wdt->base);
374  err_free:
375         kfree(wdt);
376  err_out:
377         return ret;
378 }
379
380 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
381 {
382         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
383
384         platform_set_drvdata(dev, NULL);
385
386         misc_deregister(&mpcore_wdt_miscdev);
387
388         mpcore_wdt_dev = NULL;
389
390         free_irq(wdt->irq, wdt);
391         iounmap(wdt->base);
392         kfree(wdt);
393         return 0;
394 }
395
396 static struct platform_driver mpcore_wdt_driver = {
397         .probe          = mpcore_wdt_probe,
398         .remove         = __devexit_p(mpcore_wdt_remove),
399         .shutdown       = mpcore_wdt_shutdown,
400         .driver         = {
401                 .owner  = THIS_MODULE,
402                 .name   = "mpcore_wdt",
403         },
404 };
405
406 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
407
408 static int __init mpcore_wdt_init(void)
409 {
410         /*
411          * Check that the margin value is within it's range;
412          * if not reset to the default
413          */
414         if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
415                 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
416                 printk(KERN_INFO "mpcore_margin value must be 0<mpcore_margin<65536, using %d\n",
417                         TIMER_MARGIN);
418         }
419
420         printk(banner, mpcore_noboot, mpcore_margin, nowayout);
421
422         return platform_driver_register(&mpcore_wdt_driver);
423 }
424
425 static void __exit mpcore_wdt_exit(void)
426 {
427         platform_driver_unregister(&mpcore_wdt_driver);
428 }
429
430 module_init(mpcore_wdt_init);
431 module_exit(mpcore_wdt_exit);
432
433 MODULE_AUTHOR("ARM Limited");
434 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
435 MODULE_LICENSE("GPL");
436 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);