Merge HEAD from ../linux-2.6
[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/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);