xref: /openbmc/linux/drivers/watchdog/pcwd_usb.c (revision bc000245)
1 /*
2  *	Berkshire USB-PC Watchdog Card Driver
3  *
4  *	(c) Copyright 2004-2007 Wim Van Sebroeck <wim@iguana.be>.
5  *
6  *	Based on source code of the following authors:
7  *	  Ken Hollis <kenji@bitgate.com>,
8  *	  Alan Cox <alan@lxorguk.ukuu.org.uk>,
9  *	  Matt Domsch <Matt_Domsch@dell.com>,
10  *	  Rob Radez <rob@osinvestor.com>,
11  *	  Greg Kroah-Hartman <greg@kroah.com>
12  *
13  *	This program is free software; you can redistribute it and/or
14  *	modify it under the terms of the GNU General Public License
15  *	as published by the Free Software Foundation; either version
16  *	2 of the License, or (at your option) any later version.
17  *
18  *	Neither Wim Van Sebroeck nor Iguana vzw. admit liability nor
19  *	provide warranty for any of this software. This material is
20  *	provided "AS-IS" and at no charge.
21  *
22  *	Thanks also to Simon Machell at Berkshire Products Inc. for
23  *	providing the test hardware. More info is available at
24  *	http://www.berkprod.com/ or http://www.pcwatchdog.com/
25  */
26 
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28 
29 #include <linux/module.h>	/* For module specific items */
30 #include <linux/moduleparam.h>	/* For new moduleparam's */
31 #include <linux/types.h>	/* For standard types (like size_t) */
32 #include <linux/errno.h>	/* For the -ENODEV/... values */
33 #include <linux/kernel.h>	/* For printk/panic/... */
34 #include <linux/delay.h>	/* For mdelay function */
35 #include <linux/miscdevice.h>	/* For struct miscdevice */
36 #include <linux/watchdog.h>	/* For the watchdog specific items */
37 #include <linux/notifier.h>	/* For notifier support */
38 #include <linux/reboot.h>	/* For reboot_notifier stuff */
39 #include <linux/init.h>		/* For __init/__exit/... */
40 #include <linux/fs.h>		/* For file operations */
41 #include <linux/usb.h>		/* For USB functions */
42 #include <linux/slab.h>		/* For kmalloc, ... */
43 #include <linux/mutex.h>	/* For mutex locking */
44 #include <linux/hid.h>		/* For HID_REQ_SET_REPORT & HID_DT_REPORT */
45 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
46 
47 #ifdef CONFIG_USB_DEBUG
48 static int debug = 1;
49 #else
50 static int debug;
51 #endif
52 
53 /* Use our own dbg macro */
54 
55 #undef dbg
56 #ifndef DEBUG
57 #define DEBUG
58 #endif
59 #define dbg(format, ...)				\
60 do {							\
61 	if (debug)					\
62 		pr_debug(format "\n", ##__VA_ARGS__);	\
63 } while (0)
64 
65 /* Module and Version Information */
66 #define DRIVER_VERSION "1.02"
67 #define DRIVER_AUTHOR "Wim Van Sebroeck <wim@iguana.be>"
68 #define DRIVER_DESC "Berkshire USB-PC Watchdog driver"
69 #define DRIVER_LICENSE "GPL"
70 #define DRIVER_NAME "pcwd_usb"
71 
72 MODULE_AUTHOR(DRIVER_AUTHOR);
73 MODULE_DESCRIPTION(DRIVER_DESC);
74 MODULE_LICENSE(DRIVER_LICENSE);
75 
76 /* Module Parameters */
77 module_param(debug, int, 0);
78 MODULE_PARM_DESC(debug, "Debug enabled or not");
79 
80 #define WATCHDOG_HEARTBEAT 0	/* default heartbeat =
81 						delay-time from dip-switches */
82 static int heartbeat = WATCHDOG_HEARTBEAT;
83 module_param(heartbeat, int, 0);
84 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. "
85 	"(0<heartbeat<65536 or 0=delay-time from dip-switches, default="
86 				__MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
87 
88 static bool nowayout = WATCHDOG_NOWAYOUT;
89 module_param(nowayout, bool, 0);
90 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
91 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
92 
93 /* The vendor and product id's for the USB-PC Watchdog card */
94 #define USB_PCWD_VENDOR_ID	0x0c98
95 #define USB_PCWD_PRODUCT_ID	0x1140
96 
97 /* table of devices that work with this driver */
98 static struct usb_device_id usb_pcwd_table[] = {
99 	{ USB_DEVICE(USB_PCWD_VENDOR_ID, USB_PCWD_PRODUCT_ID) },
100 	{ }					/* Terminating entry */
101 };
102 MODULE_DEVICE_TABLE(usb, usb_pcwd_table);
103 
104 /* according to documentation max. time to process a command for the USB
105  * watchdog card is 100 or 200 ms, so we give it 250 ms to do it's job */
106 #define USB_COMMAND_TIMEOUT	250
107 
108 /* Watchdog's internal commands */
109 #define CMD_READ_TEMP			0x02	/* Read Temperature;
110 							Re-trigger Watchdog */
111 #define CMD_TRIGGER			CMD_READ_TEMP
112 #define CMD_GET_STATUS			0x04	/* Get Status Information */
113 #define CMD_GET_FIRMWARE_VERSION	0x08	/* Get Firmware Version */
114 #define CMD_GET_DIP_SWITCH_SETTINGS	0x0c	/* Get Dip Switch Settings */
115 #define CMD_READ_WATCHDOG_TIMEOUT	0x18	/* Read Current Watchdog Time */
116 #define CMD_WRITE_WATCHDOG_TIMEOUT	0x19	/* Write Current WatchdogTime */
117 #define CMD_ENABLE_WATCHDOG		0x30	/* Enable / Disable Watchdog */
118 #define CMD_DISABLE_WATCHDOG		CMD_ENABLE_WATCHDOG
119 
120 /* Watchdog's Dip Switch heartbeat values */
121 static const int heartbeat_tbl[] = {
122 	5,	/* OFF-OFF-OFF	=  5 Sec  */
123 	10,	/* OFF-OFF-ON	= 10 Sec  */
124 	30,	/* OFF-ON-OFF	= 30 Sec  */
125 	60,	/* OFF-ON-ON	=  1 Min  */
126 	300,	/* ON-OFF-OFF	=  5 Min  */
127 	600,	/* ON-OFF-ON	= 10 Min  */
128 	1800,	/* ON-ON-OFF	= 30 Min  */
129 	3600,	/* ON-ON-ON	=  1 hour */
130 };
131 
132 /* We can only use 1 card due to the /dev/watchdog restriction */
133 static int cards_found;
134 
135 /* some internal variables */
136 static unsigned long is_active;
137 static char expect_release;
138 
139 /* Structure to hold all of our device specific stuff */
140 struct usb_pcwd_private {
141 	/* save off the usb device pointer */
142 	struct usb_device	*udev;
143 	/* the interface for this device */
144 	struct usb_interface	*interface;
145 
146 	/* the interface number used for cmd's */
147 	unsigned int		interface_number;
148 
149 	/* the buffer to intr data */
150 	unsigned char		*intr_buffer;
151 	/* the dma address for the intr buffer */
152 	dma_addr_t		intr_dma;
153 	/* the size of the intr buffer */
154 	size_t			intr_size;
155 	/* the urb used for the intr pipe */
156 	struct urb		*intr_urb;
157 
158 	/* The command that is reported back */
159 	unsigned char		cmd_command;
160 	/* The data MSB that is reported back */
161 	unsigned char		cmd_data_msb;
162 	/* The data LSB that is reported back */
163 	unsigned char		cmd_data_lsb;
164 	/* true if we received a report after a command */
165 	atomic_t		cmd_received;
166 
167 	/* Wether or not the device exists */
168 	int			exists;
169 	/* locks this structure */
170 	struct mutex		mtx;
171 };
172 static struct usb_pcwd_private *usb_pcwd_device;
173 
174 /* prevent races between open() and disconnect() */
175 static DEFINE_MUTEX(disconnect_mutex);
176 
177 /* local function prototypes */
178 static int usb_pcwd_probe(struct usb_interface *interface,
179 						const struct usb_device_id *id);
180 static void usb_pcwd_disconnect(struct usb_interface *interface);
181 
182 /* usb specific object needed to register this driver with the usb subsystem */
183 static struct usb_driver usb_pcwd_driver = {
184 	.name =		DRIVER_NAME,
185 	.probe =	usb_pcwd_probe,
186 	.disconnect =	usb_pcwd_disconnect,
187 	.id_table =	usb_pcwd_table,
188 };
189 
190 
191 static void usb_pcwd_intr_done(struct urb *urb)
192 {
193 	struct usb_pcwd_private *usb_pcwd =
194 				(struct usb_pcwd_private *)urb->context;
195 	unsigned char *data = usb_pcwd->intr_buffer;
196 	int retval;
197 
198 	switch (urb->status) {
199 	case 0:			/* success */
200 		break;
201 	case -ECONNRESET:	/* unlink */
202 	case -ENOENT:
203 	case -ESHUTDOWN:
204 		/* this urb is terminated, clean up */
205 		dbg("%s - urb shutting down with status: %d", __func__,
206 								urb->status);
207 		return;
208 	/* -EPIPE:  should clear the halt */
209 	default:		/* error */
210 		dbg("%s - nonzero urb status received: %d", __func__,
211 								urb->status);
212 		goto resubmit;
213 	}
214 
215 	dbg("received following data cmd=0x%02x msb=0x%02x lsb=0x%02x",
216 		data[0], data[1], data[2]);
217 
218 	usb_pcwd->cmd_command  = data[0];
219 	usb_pcwd->cmd_data_msb = data[1];
220 	usb_pcwd->cmd_data_lsb = data[2];
221 
222 	/* notify anyone waiting that the cmd has finished */
223 	atomic_set(&usb_pcwd->cmd_received, 1);
224 
225 resubmit:
226 	retval = usb_submit_urb(urb, GFP_ATOMIC);
227 	if (retval)
228 		pr_err("can't resubmit intr, usb_submit_urb failed with result %d\n",
229 		       retval);
230 }
231 
232 static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
233 		unsigned char cmd, unsigned char *msb, unsigned char *lsb)
234 {
235 	int got_response, count;
236 	unsigned char *buf;
237 
238 	/* We will not send any commands if the USB PCWD device does
239 	 * not exist */
240 	if ((!usb_pcwd) || (!usb_pcwd->exists))
241 		return -1;
242 
243 	buf = kmalloc(6, GFP_KERNEL);
244 	if (buf == NULL)
245 		return 0;
246 
247 	/* The USB PC Watchdog uses a 6 byte report format.
248 	 * The board currently uses only 3 of the six bytes of the report. */
249 	buf[0] = cmd;			/* Byte 0 = CMD */
250 	buf[1] = *msb;			/* Byte 1 = Data MSB */
251 	buf[2] = *lsb;			/* Byte 2 = Data LSB */
252 	buf[3] = buf[4] = buf[5] = 0;	/* All other bytes not used */
253 
254 	dbg("sending following data cmd=0x%02x msb=0x%02x lsb=0x%02x",
255 		buf[0], buf[1], buf[2]);
256 
257 	atomic_set(&usb_pcwd->cmd_received, 0);
258 
259 	if (usb_control_msg(usb_pcwd->udev, usb_sndctrlpipe(usb_pcwd->udev, 0),
260 			HID_REQ_SET_REPORT, HID_DT_REPORT,
261 			0x0200, usb_pcwd->interface_number, buf, 6,
262 			USB_COMMAND_TIMEOUT) != 6) {
263 		dbg("usb_pcwd_send_command: error in usb_control_msg for "
264 				"cmd 0x%x 0x%x 0x%x\n", cmd, *msb, *lsb);
265 	}
266 	/* wait till the usb card processed the command,
267 	 * with a max. timeout of USB_COMMAND_TIMEOUT */
268 	got_response = 0;
269 	for (count = 0; (count < USB_COMMAND_TIMEOUT) && (!got_response);
270 								count++) {
271 		mdelay(1);
272 		if (atomic_read(&usb_pcwd->cmd_received))
273 			got_response = 1;
274 	}
275 
276 	if ((got_response) && (cmd == usb_pcwd->cmd_command)) {
277 		/* read back response */
278 		*msb = usb_pcwd->cmd_data_msb;
279 		*lsb = usb_pcwd->cmd_data_lsb;
280 	}
281 
282 	kfree(buf);
283 
284 	return got_response;
285 }
286 
287 static int usb_pcwd_start(struct usb_pcwd_private *usb_pcwd)
288 {
289 	unsigned char msb = 0x00;
290 	unsigned char lsb = 0x00;
291 	int retval;
292 
293 	/* Enable Watchdog */
294 	retval = usb_pcwd_send_command(usb_pcwd, CMD_ENABLE_WATCHDOG,
295 								&msb, &lsb);
296 
297 	if ((retval == 0) || (lsb == 0)) {
298 		pr_err("Card did not acknowledge enable attempt\n");
299 		return -1;
300 	}
301 
302 	return 0;
303 }
304 
305 static int usb_pcwd_stop(struct usb_pcwd_private *usb_pcwd)
306 {
307 	unsigned char msb = 0xA5;
308 	unsigned char lsb = 0xC3;
309 	int retval;
310 
311 	/* Disable Watchdog */
312 	retval = usb_pcwd_send_command(usb_pcwd, CMD_DISABLE_WATCHDOG,
313 								&msb, &lsb);
314 
315 	if ((retval == 0) || (lsb != 0)) {
316 		pr_err("Card did not acknowledge disable attempt\n");
317 		return -1;
318 	}
319 
320 	return 0;
321 }
322 
323 static int usb_pcwd_keepalive(struct usb_pcwd_private *usb_pcwd)
324 {
325 	unsigned char dummy;
326 
327 	/* Re-trigger Watchdog */
328 	usb_pcwd_send_command(usb_pcwd, CMD_TRIGGER, &dummy, &dummy);
329 
330 	return 0;
331 }
332 
333 static int usb_pcwd_set_heartbeat(struct usb_pcwd_private *usb_pcwd, int t)
334 {
335 	unsigned char msb = t / 256;
336 	unsigned char lsb = t % 256;
337 
338 	if ((t < 0x0001) || (t > 0xFFFF))
339 		return -EINVAL;
340 
341 	/* Write new heartbeat to watchdog */
342 	usb_pcwd_send_command(usb_pcwd, CMD_WRITE_WATCHDOG_TIMEOUT, &msb, &lsb);
343 
344 	heartbeat = t;
345 	return 0;
346 }
347 
348 static int usb_pcwd_get_temperature(struct usb_pcwd_private *usb_pcwd,
349 							int *temperature)
350 {
351 	unsigned char msb, lsb;
352 
353 	usb_pcwd_send_command(usb_pcwd, CMD_READ_TEMP, &msb, &lsb);
354 
355 	/*
356 	 * Convert celsius to fahrenheit, since this was
357 	 * the decided 'standard' for this return value.
358 	 */
359 	*temperature = (lsb * 9 / 5) + 32;
360 
361 	return 0;
362 }
363 
364 static int usb_pcwd_get_timeleft(struct usb_pcwd_private *usb_pcwd,
365 								int *time_left)
366 {
367 	unsigned char msb, lsb;
368 
369 	/* Read the time that's left before rebooting */
370 	/* Note: if the board is not yet armed then we will read 0xFFFF */
371 	usb_pcwd_send_command(usb_pcwd, CMD_READ_WATCHDOG_TIMEOUT, &msb, &lsb);
372 
373 	*time_left = (msb << 8) + lsb;
374 
375 	return 0;
376 }
377 
378 /*
379  *	/dev/watchdog handling
380  */
381 
382 static ssize_t usb_pcwd_write(struct file *file, const char __user *data,
383 						size_t len, loff_t *ppos)
384 {
385 	/* See if we got the magic character 'V' and reload the timer */
386 	if (len) {
387 		if (!nowayout) {
388 			size_t i;
389 
390 			/* note: just in case someone wrote the magic character
391 			 * five months ago... */
392 			expect_release = 0;
393 
394 			/* scan to see whether or not we got the
395 			 * magic character */
396 			for (i = 0; i != len; i++) {
397 				char c;
398 				if (get_user(c, data + i))
399 					return -EFAULT;
400 				if (c == 'V')
401 					expect_release = 42;
402 			}
403 		}
404 
405 		/* someone wrote to us, we should reload the timer */
406 		usb_pcwd_keepalive(usb_pcwd_device);
407 	}
408 	return len;
409 }
410 
411 static long usb_pcwd_ioctl(struct file *file, unsigned int cmd,
412 						unsigned long arg)
413 {
414 	void __user *argp = (void __user *)arg;
415 	int __user *p = argp;
416 	static const struct watchdog_info ident = {
417 		.options =		WDIOF_KEEPALIVEPING |
418 					WDIOF_SETTIMEOUT |
419 					WDIOF_MAGICCLOSE,
420 		.firmware_version =	1,
421 		.identity =		DRIVER_NAME,
422 	};
423 
424 	switch (cmd) {
425 	case WDIOC_GETSUPPORT:
426 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
427 
428 	case WDIOC_GETSTATUS:
429 	case WDIOC_GETBOOTSTATUS:
430 		return put_user(0, p);
431 
432 	case WDIOC_GETTEMP:
433 	{
434 		int temperature;
435 
436 		if (usb_pcwd_get_temperature(usb_pcwd_device, &temperature))
437 			return -EFAULT;
438 
439 		return put_user(temperature, p);
440 	}
441 
442 	case WDIOC_SETOPTIONS:
443 	{
444 		int new_options, retval = -EINVAL;
445 
446 		if (get_user(new_options, p))
447 			return -EFAULT;
448 
449 		if (new_options & WDIOS_DISABLECARD) {
450 			usb_pcwd_stop(usb_pcwd_device);
451 			retval = 0;
452 		}
453 
454 		if (new_options & WDIOS_ENABLECARD) {
455 			usb_pcwd_start(usb_pcwd_device);
456 			retval = 0;
457 		}
458 
459 		return retval;
460 	}
461 
462 	case WDIOC_KEEPALIVE:
463 		usb_pcwd_keepalive(usb_pcwd_device);
464 		return 0;
465 
466 	case WDIOC_SETTIMEOUT:
467 	{
468 		int new_heartbeat;
469 
470 		if (get_user(new_heartbeat, p))
471 			return -EFAULT;
472 
473 		if (usb_pcwd_set_heartbeat(usb_pcwd_device, new_heartbeat))
474 			return -EINVAL;
475 
476 		usb_pcwd_keepalive(usb_pcwd_device);
477 		/* Fall */
478 	}
479 
480 	case WDIOC_GETTIMEOUT:
481 		return put_user(heartbeat, p);
482 
483 	case WDIOC_GETTIMELEFT:
484 	{
485 		int time_left;
486 
487 		if (usb_pcwd_get_timeleft(usb_pcwd_device, &time_left))
488 			return -EFAULT;
489 
490 		return put_user(time_left, p);
491 	}
492 
493 	default:
494 		return -ENOTTY;
495 	}
496 }
497 
498 static int usb_pcwd_open(struct inode *inode, struct file *file)
499 {
500 	/* /dev/watchdog can only be opened once */
501 	if (test_and_set_bit(0, &is_active))
502 		return -EBUSY;
503 
504 	/* Activate */
505 	usb_pcwd_start(usb_pcwd_device);
506 	usb_pcwd_keepalive(usb_pcwd_device);
507 	return nonseekable_open(inode, file);
508 }
509 
510 static int usb_pcwd_release(struct inode *inode, struct file *file)
511 {
512 	/*
513 	 *      Shut off the timer.
514 	 */
515 	if (expect_release == 42) {
516 		usb_pcwd_stop(usb_pcwd_device);
517 	} else {
518 		pr_crit("Unexpected close, not stopping watchdog!\n");
519 		usb_pcwd_keepalive(usb_pcwd_device);
520 	}
521 	expect_release = 0;
522 	clear_bit(0, &is_active);
523 	return 0;
524 }
525 
526 /*
527  *	/dev/temperature handling
528  */
529 
530 static ssize_t usb_pcwd_temperature_read(struct file *file, char __user *data,
531 				size_t len, loff_t *ppos)
532 {
533 	int temperature;
534 
535 	if (usb_pcwd_get_temperature(usb_pcwd_device, &temperature))
536 		return -EFAULT;
537 
538 	if (copy_to_user(data, &temperature, 1))
539 		return -EFAULT;
540 
541 	return 1;
542 }
543 
544 static int usb_pcwd_temperature_open(struct inode *inode, struct file *file)
545 {
546 	return nonseekable_open(inode, file);
547 }
548 
549 static int usb_pcwd_temperature_release(struct inode *inode, struct file *file)
550 {
551 	return 0;
552 }
553 
554 /*
555  *	Notify system
556  */
557 
558 static int usb_pcwd_notify_sys(struct notifier_block *this, unsigned long code,
559 								void *unused)
560 {
561 	if (code == SYS_DOWN || code == SYS_HALT)
562 		usb_pcwd_stop(usb_pcwd_device);	/* Turn the WDT off */
563 
564 	return NOTIFY_DONE;
565 }
566 
567 /*
568  *	Kernel Interfaces
569  */
570 
571 static const struct file_operations usb_pcwd_fops = {
572 	.owner =	THIS_MODULE,
573 	.llseek =	no_llseek,
574 	.write =	usb_pcwd_write,
575 	.unlocked_ioctl = usb_pcwd_ioctl,
576 	.open =		usb_pcwd_open,
577 	.release =	usb_pcwd_release,
578 };
579 
580 static struct miscdevice usb_pcwd_miscdev = {
581 	.minor =	WATCHDOG_MINOR,
582 	.name =		"watchdog",
583 	.fops =		&usb_pcwd_fops,
584 };
585 
586 static const struct file_operations usb_pcwd_temperature_fops = {
587 	.owner =	THIS_MODULE,
588 	.llseek =	no_llseek,
589 	.read =		usb_pcwd_temperature_read,
590 	.open =		usb_pcwd_temperature_open,
591 	.release =	usb_pcwd_temperature_release,
592 };
593 
594 static struct miscdevice usb_pcwd_temperature_miscdev = {
595 	.minor =	TEMP_MINOR,
596 	.name =		"temperature",
597 	.fops =		&usb_pcwd_temperature_fops,
598 };
599 
600 static struct notifier_block usb_pcwd_notifier = {
601 	.notifier_call =	usb_pcwd_notify_sys,
602 };
603 
604 /**
605  *	usb_pcwd_delete
606  */
607 static inline void usb_pcwd_delete(struct usb_pcwd_private *usb_pcwd)
608 {
609 	usb_free_urb(usb_pcwd->intr_urb);
610 	if (usb_pcwd->intr_buffer != NULL)
611 		usb_free_coherent(usb_pcwd->udev, usb_pcwd->intr_size,
612 				  usb_pcwd->intr_buffer, usb_pcwd->intr_dma);
613 	kfree(usb_pcwd);
614 }
615 
616 /**
617  *	usb_pcwd_probe
618  *
619  *	Called by the usb core when a new device is connected that it thinks
620  *	this driver might be interested in.
621  */
622 static int usb_pcwd_probe(struct usb_interface *interface,
623 						const struct usb_device_id *id)
624 {
625 	struct usb_device *udev = interface_to_usbdev(interface);
626 	struct usb_host_interface *iface_desc;
627 	struct usb_endpoint_descriptor *endpoint;
628 	struct usb_pcwd_private *usb_pcwd = NULL;
629 	int pipe, maxp;
630 	int retval = -ENOMEM;
631 	int got_fw_rev;
632 	unsigned char fw_rev_major, fw_rev_minor;
633 	char fw_ver_str[20];
634 	unsigned char option_switches, dummy;
635 
636 	cards_found++;
637 	if (cards_found > 1) {
638 		pr_err("This driver only supports 1 device\n");
639 		return -ENODEV;
640 	}
641 
642 	/* get the active interface descriptor */
643 	iface_desc = interface->cur_altsetting;
644 
645 	/* check out that we have a HID device */
646 	if (!(iface_desc->desc.bInterfaceClass == USB_CLASS_HID)) {
647 		pr_err("The device isn't a Human Interface Device\n");
648 		return -ENODEV;
649 	}
650 
651 	/* check out the endpoint: it has to be Interrupt & IN */
652 	endpoint = &iface_desc->endpoint[0].desc;
653 
654 	if (!usb_endpoint_is_int_in(endpoint)) {
655 		/* we didn't find a Interrupt endpoint with direction IN */
656 		pr_err("Couldn't find an INTR & IN endpoint\n");
657 		return -ENODEV;
658 	}
659 
660 	/* get a handle to the interrupt data pipe */
661 	pipe = usb_rcvintpipe(udev, endpoint->bEndpointAddress);
662 	maxp = usb_maxpacket(udev, pipe, usb_pipeout(pipe));
663 
664 	/* allocate memory for our device and initialize it */
665 	usb_pcwd = kzalloc(sizeof(struct usb_pcwd_private), GFP_KERNEL);
666 	if (usb_pcwd == NULL) {
667 		pr_err("Out of memory\n");
668 		goto error;
669 	}
670 
671 	usb_pcwd_device = usb_pcwd;
672 
673 	mutex_init(&usb_pcwd->mtx);
674 	usb_pcwd->udev = udev;
675 	usb_pcwd->interface = interface;
676 	usb_pcwd->interface_number = iface_desc->desc.bInterfaceNumber;
677 	usb_pcwd->intr_size = (le16_to_cpu(endpoint->wMaxPacketSize) > 8 ?
678 				le16_to_cpu(endpoint->wMaxPacketSize) : 8);
679 
680 	/* set up the memory buffer's */
681 	usb_pcwd->intr_buffer = usb_alloc_coherent(udev, usb_pcwd->intr_size,
682 					GFP_ATOMIC, &usb_pcwd->intr_dma);
683 	if (!usb_pcwd->intr_buffer) {
684 		pr_err("Out of memory\n");
685 		goto error;
686 	}
687 
688 	/* allocate the urb's */
689 	usb_pcwd->intr_urb = usb_alloc_urb(0, GFP_KERNEL);
690 	if (!usb_pcwd->intr_urb) {
691 		pr_err("Out of memory\n");
692 		goto error;
693 	}
694 
695 	/* initialise the intr urb's */
696 	usb_fill_int_urb(usb_pcwd->intr_urb, udev, pipe,
697 			usb_pcwd->intr_buffer, usb_pcwd->intr_size,
698 			usb_pcwd_intr_done, usb_pcwd, endpoint->bInterval);
699 	usb_pcwd->intr_urb->transfer_dma = usb_pcwd->intr_dma;
700 	usb_pcwd->intr_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
701 
702 	/* register our interrupt URB with the USB system */
703 	if (usb_submit_urb(usb_pcwd->intr_urb, GFP_KERNEL)) {
704 		pr_err("Problem registering interrupt URB\n");
705 		retval = -EIO; /* failure */
706 		goto error;
707 	}
708 
709 	/* The device exists and can be communicated with */
710 	usb_pcwd->exists = 1;
711 
712 	/* disable card */
713 	usb_pcwd_stop(usb_pcwd);
714 
715 	/* Get the Firmware Version */
716 	got_fw_rev = usb_pcwd_send_command(usb_pcwd, CMD_GET_FIRMWARE_VERSION,
717 						&fw_rev_major, &fw_rev_minor);
718 	if (got_fw_rev)
719 		sprintf(fw_ver_str, "%u.%02u", fw_rev_major, fw_rev_minor);
720 	else
721 		sprintf(fw_ver_str, "<card no answer>");
722 
723 	pr_info("Found card (Firmware: %s) with temp option\n", fw_ver_str);
724 
725 	/* Get switch settings */
726 	usb_pcwd_send_command(usb_pcwd, CMD_GET_DIP_SWITCH_SETTINGS, &dummy,
727 							&option_switches);
728 
729 	pr_info("Option switches (0x%02x): Temperature Reset Enable=%s, Power On Delay=%s\n",
730 		option_switches,
731 		((option_switches & 0x10) ? "ON" : "OFF"),
732 		((option_switches & 0x08) ? "ON" : "OFF"));
733 
734 	/* If heartbeat = 0 then we use the heartbeat from the dip-switches */
735 	if (heartbeat == 0)
736 		heartbeat = heartbeat_tbl[(option_switches & 0x07)];
737 
738 	/* Check that the heartbeat value is within it's range ;
739 	 * if not reset to the default */
740 	if (usb_pcwd_set_heartbeat(usb_pcwd, heartbeat)) {
741 		usb_pcwd_set_heartbeat(usb_pcwd, WATCHDOG_HEARTBEAT);
742 		pr_info("heartbeat value must be 0<heartbeat<65536, using %d\n",
743 			WATCHDOG_HEARTBEAT);
744 	}
745 
746 	retval = register_reboot_notifier(&usb_pcwd_notifier);
747 	if (retval != 0) {
748 		pr_err("cannot register reboot notifier (err=%d)\n", retval);
749 		goto error;
750 	}
751 
752 	retval = misc_register(&usb_pcwd_temperature_miscdev);
753 	if (retval != 0) {
754 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
755 		       TEMP_MINOR, retval);
756 		goto err_out_unregister_reboot;
757 	}
758 
759 	retval = misc_register(&usb_pcwd_miscdev);
760 	if (retval != 0) {
761 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
762 		       WATCHDOG_MINOR, retval);
763 		goto err_out_misc_deregister;
764 	}
765 
766 	/* we can register the device now, as it is ready */
767 	usb_set_intfdata(interface, usb_pcwd);
768 
769 	pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
770 		heartbeat, nowayout);
771 
772 	return 0;
773 
774 err_out_misc_deregister:
775 	misc_deregister(&usb_pcwd_temperature_miscdev);
776 err_out_unregister_reboot:
777 	unregister_reboot_notifier(&usb_pcwd_notifier);
778 error:
779 	if (usb_pcwd)
780 		usb_pcwd_delete(usb_pcwd);
781 	usb_pcwd_device = NULL;
782 	return retval;
783 }
784 
785 
786 /**
787  *	usb_pcwd_disconnect
788  *
789  *	Called by the usb core when the device is removed from the system.
790  *
791  *	This routine guarantees that the driver will not submit any more urbs
792  *	by clearing dev->udev.
793  */
794 static void usb_pcwd_disconnect(struct usb_interface *interface)
795 {
796 	struct usb_pcwd_private *usb_pcwd;
797 
798 	/* prevent races with open() */
799 	mutex_lock(&disconnect_mutex);
800 
801 	usb_pcwd = usb_get_intfdata(interface);
802 	usb_set_intfdata(interface, NULL);
803 
804 	mutex_lock(&usb_pcwd->mtx);
805 
806 	/* Stop the timer before we leave */
807 	if (!nowayout)
808 		usb_pcwd_stop(usb_pcwd);
809 
810 	/* We should now stop communicating with the USB PCWD device */
811 	usb_pcwd->exists = 0;
812 
813 	/* Deregister */
814 	misc_deregister(&usb_pcwd_miscdev);
815 	misc_deregister(&usb_pcwd_temperature_miscdev);
816 	unregister_reboot_notifier(&usb_pcwd_notifier);
817 
818 	mutex_unlock(&usb_pcwd->mtx);
819 
820 	/* Delete the USB PCWD device */
821 	usb_pcwd_delete(usb_pcwd);
822 
823 	cards_found--;
824 
825 	mutex_unlock(&disconnect_mutex);
826 
827 	pr_info("USB PC Watchdog disconnected\n");
828 }
829 
830 module_usb_driver(usb_pcwd_driver);
831