path: root/drivers/char/watchdog/pcwd_usb.c

/*
 *	Berkshire USB-PC Watchdog Card Driver
 *
 *	(c) Copyright 2004 Wim Van Sebroeck <wim@iguana.be>.
 *
 *	Based on source code of the following authors:
 *	  Ken Hollis <kenji@bitgate.com>,
 *	  Alan Cox <alan@redhat.com>,
 *	  Matt Domsch <Matt_Domsch@dell.com>,
 *	  Rob Radez <rob@osinvestor.com>,
 *	  Greg Kroah-Hartman <greg@kroah.com>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	Neither Wim Van Sebroeck nor Iguana vzw. admit liability nor
 *	provide warranty for any of this software. This material is
 *	provided "AS-IS" and at no charge.
 *
 *	Thanks also to Simon Machell at Berkshire Products Inc. for
 *	providing the test hardware. More info is available at
 *	http://www.berkprod.com/ or http://www.pcwatchdog.com/
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>
#include <asm/uaccess.h>
#include <linux/usb.h>


#ifdef CONFIG_USB_DEBUG
	static int debug = 1;
#else
	static int debug;
#endif

/* Use our own dbg macro */
#undef dbg
#define dbg(format, arg...) do { if (debug) printk(KERN_DEBUG PFX format "\n" , ## arg); } while (0)


/* Module and Version Information */
#define DRIVER_VERSION "1.01"
#define DRIVER_DATE "15 Mar 2005"
#define DRIVER_AUTHOR "Wim Van Sebroeck <wim@iguana.be>"
#define DRIVER_DESC "Berkshire USB-PC Watchdog driver"
#define DRIVER_LICENSE "GPL"
#define DRIVER_NAME "pcwd_usb"
#define PFX DRIVER_NAME ": "

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE(DRIVER_LICENSE);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS_MISCDEV(TEMP_MINOR);

/* Module Parameters */
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug enabled or not");

#define WATCHDOG_HEARTBEAT 2	/* 2 sec default heartbeat */
static int heartbeat = WATCHDOG_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (0<heartbeat<65536, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
#else
static int nowayout = 0;
#endif

module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

/* The vendor and product id's for the USB-PC Watchdog card */
#define USB_PCWD_VENDOR_ID	0x0c98
#define USB_PCWD_PRODUCT_ID	0x1140

/* table of devices that work with this driver */
static struct usb_device_id usb_pcwd_table [] = {
	{ USB_DEVICE(USB_PCWD_VENDOR_ID, USB_PCWD_PRODUCT_ID) },
	{ }					/* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, usb_pcwd_table);

/* according to documentation max. time to process a command for the USB
 * watchdog card is 100 or 200 ms, so we give it 250 ms to do it's job */
#define USB_COMMAND_TIMEOUT	250

/* Watchdog's internal commands */
#define CMD_READ_TEMP			0x02	/* Read Temperature; Re-trigger Watchdog */
#define CMD_TRIGGER			CMD_READ_TEMP
#define CMD_GET_STATUS			0x04	/* Get Status Information */
#define CMD_GET_FIRMWARE_VERSION	0x08	/* Get Firmware Version */
#define CMD_GET_DIP_SWITCH_SETTINGS	0x0c	/* Get Dip Switch Settings */
#define CMD_READ_WATCHDOG_TIMEOUT	0x18	/* Read Current Watchdog Time */
#define CMD_WRITE_WATCHDOG_TIMEOUT	0x19	/* Write Current Watchdog Time */
#define CMD_ENABLE_WATCHDOG		0x30	/* Enable / Disable Watchdog */
#define CMD_DISABLE_WATCHDOG		CMD_ENABLE_WATCHDOG

/* Some defines that I like to be somewhere else like include/linux/usb_hid.h */
#define HID_REQ_SET_REPORT		0x09
#define HID_DT_REPORT			(USB_TYPE_CLASS | 0x02)

/* We can only use 1 card due to the /dev/watchdog restriction */
static int cards_found;

/* some internal variables */
static unsigned long is_active;
static char expect_release;

/* Structure to hold all of our device specific stuff */
struct usb_pcwd_private {
	struct usb_device *	udev;			/* save off the usb device pointer */
	struct usb_interface *	interface;		/* the interface for this device */

	unsigned int		interface_number;	/* the interface number used for cmd's */

	unsigned char *		intr_buffer;		/* the buffer to intr data */
	dma_addr_t		intr_dma;		/* the dma address for the intr buffer */
	size_t			intr_size;		/* the size of the intr buffer */
	struct urb *		intr_urb;		/* the urb used for the intr pipe */

	unsigned char		cmd_command;		/* The command that is reported back */
	unsigned char		cmd_data_msb;		/* The data MSB that is reported back */
	unsigned char		cmd_data_lsb;		/* The data LSB that is reported back */
	atomic_t		cmd_received;		/* true if we received a report after a command */

	int			exists;			/* Wether or not the device exists */
	struct semaphore	sem;			/* locks this structure */
};
static struct usb_pcwd_private *usb_pcwd_device;

/* prevent races between open() and disconnect() */
static DECLARE_MUTEX (disconnect_sem);

/* local function prototypes */
static int usb_pcwd_probe	(struct usb_interface *interface, const struct usb_device_id *id);
static void usb_pcwd_disconnect	(struct usb_interface *interface);

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver usb_pcwd_driver = {
	.owner =	THIS_MODULE,
	.name =		DRIVER_NAME,
	.probe =	usb_pcwd_probe,
	.disconnect =	usb_pcwd_disconnect,
	.id_table =	usb_pcwd_table,
};


static void usb_pcwd_intr_done(struct urb *urb, struct pt_regs *regs)
{
	struct usb_pcwd_private *usb_pcwd = (struct usb_pcwd_private *)urb->context;
	unsigned char *data = usb_pcwd->intr_buffer;
	int retval;

	switch (urb->status) {
	case 0:			/* success */
		break;
	case -ECONNRESET:	/* unlink */
	case -ENOENT:
	case -ESHUTDOWN:
		/* this urb is terminated, clean up */
		dbg("%s - urb shutting down with status: %d", __FUNCTION__, urb->status);
		return;
	/* -EPIPE:  should clear the halt */
	default:		/* error */
		dbg("%s - nonzero urb status received: %d", __FUNCTION__, urb->status);
		goto resubmit;
	}

	dbg("received following data cmd=0x%02x msb=0x%02x lsb=0x%02x",
		data[0], data[1], data[2]);

	usb_pcwd->cmd_command  = data[0];
	usb_pcwd->cmd_data_msb = data[1];
	usb_pcwd->cmd_data_lsb = data[2];

	/* notify anyone waiting that the cmd has finished */
	atomic_set (&usb_pcwd->cmd_received, 1);

resubmit:
	retval = usb_submit_urb (urb, GFP_ATOMIC);
	if (retval)
		printk(KERN_ERR PFX "can't resubmit intr, usb_submit_urb failed with result %d\n",
			retval);
}

static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd, unsigned char cmd,
	unsigned char *msb, unsigned char *lsb)
{
	int got_response, count;
	unsigned char buf[6];

	/* We will not send any commands if the USB PCWD device does not exist */
	if ((!usb_pcwd) || (!usb_pcwd->exists))
		return -1;

	/* The USB PC Watchdog uses a 6 byte report format. The board currently uses
	 * only 3 of the six bytes of the report. */
	buf[0] = cmd;			/* Byte 0 = CMD */
	buf[1] = *msb;			/* Byte 1 = Data MSB */
	buf[2] = *lsb;			/* Byte 2 = Data LSB */
	buf[3] = buf[4] = buf[5] = 0;	/* All other bytes not used */

	dbg("sending following data cmd=0x%02x msb=0x%02x lsb=0x%02x",
		buf[0], buf[1], buf[2]);

	atomic_set (&usb_pcwd->cmd_received, 0);

	if (usb_control_msg(usb_pcwd->udev, usb_sndctrlpipe(usb_pcwd->udev, 0),
			HID_REQ_SET_REPORT, HID_DT_REPORT,
			0x0200, usb_pcwd->interface_number, buf, sizeof(buf),
			USB_COMMAND_TIMEOUT) != sizeof(buf)) {
		dbg("usb_pcwd_send_command: error in usb_control_msg for cmd 0x%x 0x%x 0x%x\n", cmd, *msb, *lsb);
	}
	/* wait till the usb card processed the command,
	 * with a max. timeout of USB_COMMAND_TIMEOUT */
	got_response = 0;
	for (count = 0; (count < USB_COMMAND_TIMEOUT) && (!got_response); count++) {
		mdelay(1);
		if (atomic_read (&usb_pcwd->cmd_received))
			got_response = 1;
	}

	if ((got_response) && (cmd == usb_pcwd->cmd_command)) {
		/* read back response */
		*msb = usb_pcwd->cmd_data_msb;
		*lsb = usb_pcwd->cmd_data_lsb;
	}

	return got_response;
}

static int usb_pcwd_start(struct usb_pcwd_private *usb_pcwd)
{
	unsigned char msb = 0x00;
	unsigned char lsb = 0x00;
	int retval;

	/* Enable Watchdog */
	retval = usb_pcwd_send_command(usb_pcwd, CMD_ENABLE_WATCHDOG, &msb, &lsb);

	if ((retval == 0) || (lsb == 0)) {
		printk(KERN_ERR PFX "Card did not acknowledge enable attempt\n");
		return -1;
	}

	return 0;
}

static int usb_pcwd_stop(struct usb_pcwd_private *usb_pcwd)
{
	unsigned char msb = 0xA5;
	unsigned char lsb = 0xC3;
	int retval;

	/* Disable Watchdog */
	retval = usb_pcwd_send_command(usb_pcwd, CMD_DISABLE_WATCHDOG, &msb, &lsb);

	if ((retval == 0) || (lsb != 0)) {
		printk(KERN_ERR PFX "Card did not acknowledge disable attempt\n");
		return -1;
	}

	return 0;
}

static int usb_pcwd_keepalive(struct usb_pcwd_private *usb_pcwd)
{
	unsigned char dummy;

	/* Re-trigger Watchdog */
	usb_pcwd_send_command(usb_pcwd, CMD_TRIGGER, &dummy, &dummy);

	return 0;
}

static int usb_pcwd_set_heartbeat(struct usb_pcwd_private *usb_pcwd, int t)
{
	unsigned char msb = t / 256;
	unsigned char lsb = t % 256;

	if ((t < 0x0001) || (t > 0xFFFF))
		return -EINVAL;

	/* Write new heartbeat to watchdog */
	usb_pcwd_send_command(usb_pcwd, CMD_WRITE_WATCHDOG_TIMEOUT, &msb, &lsb);

	heartbeat = t;
	return 0;
}

static int usb_pcwd_get_temperature(struct usb_pcwd_private *usb_pcwd, int *temperature)
{
	unsigned char msb, lsb;

	usb_pcwd_send_command(usb_pcwd, CMD_READ_TEMP, &msb, &lsb);

	/*
	 * Convert celsius to fahrenheit, since this was
	 * the decided 'standard' for this return value.
	 */
	*temperature = (lsb * 9 / 5) + 32;

	return 0;
}

/*
 *	/dev/watchdog handling
 */

static ssize_t usb_pcwd_write(struct file *file, const char __user *data,
			      size_t len, loff_t *ppos)
{
	/* See if we got the magic character 'V' and reload the timer */
	if (len) {
		if (!nowayout) {
			size_t i;

			/* note: just in case someone wrote the magic character
			 * five months ago... */
			expect_release = 0;

			/* scan to see whether or not we got the magic character */
			for (i = 0; i != len; i++) {
				char c;
				if(get_user(c, data+i))
					return -EFAULT;
				if (c == 'V')
					expect_release = 42;
			}
		}

		/* someone wrote to us, we should reload the timer */
		usb_pcwd_keepalive(usb_pcwd_device);
	}
	return len;
}

static int usb_pcwd_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static struct watchdog_info ident = {
		.options =		WDIOF_KEEPALIVEPING |
					WDIOF_SETTIMEOUT |
					WDIOF_MAGICCLOSE,
		.firmware_version =	1,
		.identity =		DRIVER_NAME,
	};

	switch (cmd) {
		case WDIOC_GETSUPPORT:
			return copy_to_user(argp, &ident,
				sizeof (ident)) ? -EFAULT : 0;

		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0, p);

		case WDIOC_GETTEMP:
		{
			int temperature;

			if (usb_pcwd_get_temperature(usb_pcwd_device, &temperature))
				return -EFAULT;

			return put_user(temperature, p);
		}

		case WDIOC_KEEPALIVE:
			usb_pcwd_keepalive(usb_pcwd_device);
			return 0;

		case WDIOC_SETOPTIONS:
		{
			int new_options, retval = -EINVAL;

			if (get_user (new_options, p))
				return -EFAULT;

			if (new_options & WDIOS_DISABLECARD) {
				usb_pcwd_stop(usb_pcwd_device);
				retval = 0;
			}

			if (new_options & WDIOS_ENABLECARD) {
				usb_pcwd_start(usb_pcwd_device);
				retval = 0;
			}

			return retval;
		}

		case WDIOC_SETTIMEOUT:
		{
			int new_heartbeat;

			if (get_user(new_heartbeat, p))
				return -EFAULT;

			if (usb_pcwd_set_heartbeat(usb_pcwd_device, new_heartbeat))
			    return -EINVAL;

			usb_pcwd_keepalive(usb_pcwd_device);
			/* Fall */
		}

		case WDIOC_GETTIMEOUT:
			return put_user(heartbeat, p);

		default:
			return -ENOIOCTLCMD;
	}
}

static int usb_pcwd_open(struct inode *inode, struct file *file)
{
	/* /dev/watchdog can only be opened once */
	if (test_and_set_bit(0, &is_active))
		return -EBUSY;

	/* Activate */
	usb_pcwd_start(usb_pcwd_device);
	usb_pcwd_keepalive(usb_pcwd_device);
	return nonseekable_open(inode, file);
}

static int usb_pcwd_release(struct inode *inode, struct file *file)
{
	/*
	 *      Shut off the timer.
	 */
	if (expect_release == 42) {
		usb_pcwd_stop(usb_pcwd_device);
	} else {
		printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
		usb_pcwd_keepalive(usb_pcwd_device);
	}
	expect_release = 0;
	clear_bit(0, &is_active);
	return 0;
}

/*
 *	/dev/temperature handling
 */

static ssize_t usb_pcwd_temperature_read(struct file *file, char __user *data,
				size_t len, loff_t *ppos)
{
	int temperature;

	if (usb_pcwd_get_temperature(usb_pcwd_device, &temperature))
		return -EFAULT;

	if (copy_to_user(data, &temperature, 1))
		return -EFAULT;

	return 1;
}

static int usb_pcwd_temperature_open(struct inode *inode, struct file *file)
{
	return nonseekable_open(inode, file);
}

static int usb_pcwd_temperature_release(struct inode *inode, struct file *file)
{
	return 0;
}

/*
 *	Notify system
 */

static int usb_pcwd_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
{
	if (code==SYS_DOWN || code==SYS_HALT) {
		/* Turn the WDT off */
		usb_pcwd_stop(usb_pcwd_device);
	}

	return NOTIFY_DONE;
}

/*
 *	Kernel Interfaces
 */

static struct file_operations usb_pcwd_fops = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,
	.write =	usb_pcwd_write,
	.ioctl =	usb_pcwd_ioctl,
	.open =		usb_pcwd_open,
	.release =	usb_pcwd_release,
};

static struct miscdevice usb_pcwd_miscdev = {
	.minor =	WATCHDOG_MINOR,
	.name =		"watchdog",
	.fops =		&usb_pcwd_fops,
};

static struct file_operations usb_pcwd_temperature_fops = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,
	.read =		usb_pcwd_temperature_read,
	.open =		usb_pcwd_temperature_open,
	.release =	usb_pcwd_temperature_release,
};

static struct miscdevice usb_pcwd_temperature_miscdev = {
	.minor =	TEMP_MINOR,
	.name =		"temperature",
	.fops =		&usb_pcwd_temperature_fops,
};

static struct notifier_block usb_pcwd_notifier = {
	.notifier_call =	usb_pcwd_notify_sys,
};

/**
 *	usb_pcwd_delete
 */
static inline void usb_pcwd_delete (struct usb_pcwd_private *usb_pcwd)
{
	if (usb_pcwd->intr_urb != NULL)
		usb_free_urb (usb_pcwd->intr_urb);
	if (usb_pcwd->intr_buffer != NULL)
		usb_buffer_free(usb_pcwd->udev, usb_pcwd->intr_size,
				usb_pcwd->intr_buffer, usb_pcwd->intr_dma);
	kfree (usb_pcwd);
}

/**
 *	usb_pcwd_probe
 *
 *	Called by the usb core when a new device is connected that it thinks
 *	this driver might be interested in.
 */
static int usb_pcwd_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(interface);
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	struct usb_pcwd_private *usb_pcwd = NULL;
	int pipe, maxp;
	int retval = -ENOMEM;
	int got_fw_rev;
	unsigned char fw_rev_major, fw_rev_minor;
	char fw_ver_str[20];
	unsigned char option_switches, dummy;

	cards_found++;
	if (cards_found > 1) {
		printk(KERN_ERR PFX "This driver only supports 1 device\n");
		return -ENODEV;
	}

	/* get the active interface descriptor */
	iface_desc = interface->cur_altsetting;

	/* check out that we have a HID device */
	if (!(iface_desc->desc.bInterfaceClass == USB_CLASS_HID)) {
		printk(KERN_ERR PFX "The device isn't a Human Interface Device\n");
		return -ENODEV;
	}

	/* check out the endpoint: it has to be Interrupt & IN */
	endpoint = &iface_desc->endpoint[0].desc;

	if (!((endpoint->bEndpointAddress & USB_DIR_IN) &&
	     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
				== USB_ENDPOINT_XFER_INT))) {
		/* we didn't find a Interrupt endpoint with direction IN */
		printk(KERN_ERR PFX "Couldn't find an INTR & IN endpoint\n");
		return -ENODEV;
	}

	/* get a handle to the interrupt data pipe */
	pipe = usb_rcvintpipe(udev, endpoint->bEndpointAddress);
	maxp = usb_maxpacket(udev, pipe, usb_pipeout(pipe));

	/* allocate memory for our device and initialize it */
	usb_pcwd = kmalloc (sizeof(struct usb_pcwd_private), GFP_KERNEL);
	if (usb_pcwd == NULL) {
		printk(KERN_ERR PFX "Out of memory\n");
		goto error;
	}
	memset (usb_pcwd, 0x00, sizeof (*usb_pcwd));

	usb_pcwd_device = usb_pcwd;

	init_MUTEX (&usb_pcwd->sem);
	usb_pcwd->udev = udev;
	usb_pcwd->interface = interface;
	usb_pcwd->interface_number = iface_desc->desc.bInterfaceNumber;
	usb_pcwd->intr_size = (le16_to_cpu(endpoint->wMaxPacketSize) > 8 ? le16_to_cpu(endpoint->wMaxPacketSize) : 8);

	/* set up the memory buffer's */
	if (!(usb_pcwd->intr_buffer = usb_buffer_alloc(udev, usb_pcwd->intr_size, SLAB_ATOMIC, &usb_pcwd->intr_dma))) {
		printk(KERN_ERR PFX "Out of memory\n");
		goto error;
	}

	/* allocate the urb's */
	usb_pcwd->intr_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!usb_pcwd->intr_urb) {
		printk(KERN_ERR PFX "Out of memory\n");
		goto error;
	}

	/* initialise the intr urb's */
	usb_fill_int_urb(usb_pcwd->intr_urb, udev, pipe,
			usb_pcwd->intr_buffer, usb_pcwd->intr_size,
			usb_pcwd_intr_done, usb_pcwd, endpoint->bInterval);
	usb_pcwd->intr_urb->transfer_dma = usb_pcwd->intr_dma;
	usb_pcwd->intr_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

	/* register our interrupt URB with the USB system */
	if (usb_submit_urb(usb_pcwd->intr_urb, GFP_KERNEL)) {
		printk(KERN_ERR PFX "Problem registering interrupt URB\n");
		retval = -EIO; /* failure */
		goto error;
	}

	/* The device exists and can be communicated with */
	usb_pcwd->exists = 1;

	/* disable card */
	usb_pcwd_stop(usb_pcwd);

	/* Get the Firmware Version */
	got_fw_rev = usb_pcwd_send_command(usb_pcwd, CMD_GET_FIRMWARE_VERSION, &fw_rev_major, &fw_rev_minor);
	if (got_fw_rev) {
		sprintf(fw_ver_str, "%u.%02u", fw_rev_major, fw_rev_minor);
	} else {
		sprintf(fw_ver_str, "<card no answer>");
	}

	printk(KERN_INFO PFX "Found card (Firmware: %s) with temp option\n",
		fw_ver_str);

	/* Get switch settings */
	usb_pcwd_send_command(usb_pcwd, CMD_GET_DIP_SWITCH_SETTINGS, &dummy, &option_switches);

	printk(KERN_INFO PFX "Option switches (0x%02x): Temperature Reset Enable=%s, Power On Delay=%s\n",
		option_switches,
		((option_switches & 0x10) ? "ON" : "OFF"),
		((option_switches & 0x08) ? "ON" : "OFF"));

	/* Check that the heartbeat value is within it's range ; if not reset to the default */
	if (usb_pcwd_set_heartbeat(usb_pcwd, heartbeat)) {
		usb_pcwd_set_heartbeat(usb_pcwd, WATCHDOG_HEARTBEAT);
		printk(KERN_INFO PFX "heartbeat value must be 0<heartbeat<65536, using %d\n",
			WATCHDOG_HEARTBEAT);
	}

	retval = register_reboot_notifier(&usb_pcwd_notifier);
	if (retval != 0) {
		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
			retval);
		goto error;
	}

	retval = misc_register(&usb_pcwd_temperature_miscdev);
	if (retval != 0) {
		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
			TEMP_MINOR, retval);
		goto err_out_unregister_reboot;
	}

	retval = misc_register(&usb_pcwd_miscdev);
	if (retval != 0) {
		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
			WATCHDOG_MINOR, retval);
		goto err_out_misc_deregister;
	}

	/* we can register the device now, as it is ready */
	usb_set_intfdata (interface, usb_pcwd);

	printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
		heartbeat, nowayout);

	return 0;

err_out_misc_deregister:
	misc_deregister(&usb_pcwd_temperature_miscdev);
err_out_unregister_reboot:
	unregister_reboot_notifier(&usb_pcwd_notifier);
error:
	usb_pcwd_delete (usb_pcwd);
	usb_pcwd_device = NULL;
	return retval;
}


/**
 *	usb_pcwd_disconnect
 *
 *	Called by the usb core when the device is removed from the system.
 *
 *	This routine guarantees that the driver will not submit any more urbs
 *	by clearing dev->udev.
 */
static void usb_pcwd_disconnect(struct usb_interface *interface)
{
	struct usb_pcwd_private *usb_pcwd;

	/* prevent races with open() */
	down (&disconnect_sem);

	usb_pcwd = usb_get_intfdata (interface);
	usb_set_intfdata (interface, NULL);

	down (&usb_pcwd->sem);

	/* Stop the timer before we leave */
	if (!nowayout)
		usb_pcwd_stop(usb_pcwd);

	/* We should now stop communicating with the USB PCWD device */
	usb_pcwd->exists = 0;

	/* Deregister */
	misc_deregister(&usb_pcwd_miscdev);
	misc_deregister(&usb_pcwd_temperature_miscdev);
	unregister_reboot_notifier(&usb_pcwd_notifier);

	up (&usb_pcwd->sem);

	/* Delete the USB PCWD device */
	usb_pcwd_delete(usb_pcwd);

	cards_found--;

	up (&disconnect_sem);

	printk(KERN_INFO PFX "USB PC Watchdog disconnected\n");
}



/**
 *	usb_pcwd_init
 */
static int __init usb_pcwd_init(void)
{
	int result;

	/* register this driver with the USB subsystem */
	result = usb_register(&usb_pcwd_driver);
	if (result) {
		printk(KERN_ERR PFX "usb_register failed. Error number %d\n",
		    result);
		return result;
	}

	printk(KERN_INFO PFX DRIVER_DESC " v" DRIVER_VERSION " (" DRIVER_DATE ")\n");
	return 0;
}


/**
 *	usb_pcwd_exit
 */
static void __exit usb_pcwd_exit(void)
{
	/* deregister this driver with the USB subsystem */
	usb_deregister(&usb_pcwd_driver);
}


module_init (usb_pcwd_init);
module_exit (usb_pcwd_exit);