/*
 *      Berkshire USB-PC Watchdog Card Driver
 *
 *      (c) Copyright 2004-2007 Wim Van Sebroeck <wim@iguana.be>.
 *
 *      Based on source code of the following authors:
 *        Ken Hollis <kenji@bitgate.com>,
 *        Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *        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/
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>       /* For module specific items */
#include <linux/moduleparam.h>  /* For new moduleparam's */
#include <linux/types.h>        /* For standard types (like size_t) */
#include <linux/errno.h>        /* For the -ENODEV/... values */
#include <linux/kernel.h>       /* For printk/panic/... */
#include <linux/delay.h>        /* For mdelay function */
#include <linux/miscdevice.h>   /* For struct miscdevice */
#include <linux/watchdog.h>     /* For the watchdog specific items */
#include <linux/notifier.h>     /* For notifier support */
#include <linux/reboot.h>       /* For reboot_notifier stuff */
#include <linux/init.h>         /* For __init/__exit/... */
#include <linux/fs.h>           /* For file operations */
#include <linux/usb.h>          /* For USB functions */
#include <linux/slab.h>         /* For kmalloc, ... */
#include <linux/mutex.h>        /* For mutex locking */
#include <linux/hid.h>          /* For HID_REQ_SET_REPORT & HID_DT_REPORT */
#include <linux/uaccess.h>      /* For copy_to_user/put_user/... */


/* Module and Version Information */
#define DRIVER_VERSION "1.02"
#define DRIVER_AUTHOR "Wim Van Sebroeck <wim@iguana.be>"
#define DRIVER_DESC "Berkshire USB-PC Watchdog driver"
#define DRIVER_NAME "pcwd_usb"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define WATCHDOG_HEARTBEAT 0    /* default heartbeat =
                                                delay-time from dip-switches */
static int heartbeat = WATCHDOG_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. "
        "(0<heartbeat<65536 or 0=delay-time from dip-switches, default="
                                __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                                __MODULE_STRING(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 const 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 WatchdogTime */
#define CMD_ENABLE_WATCHDOG             0x30    /* Enable / Disable Watchdog */
#define CMD_DISABLE_WATCHDOG            CMD_ENABLE_WATCHDOG

/* Watchdog's Dip Switch heartbeat values */
static const int heartbeat_tbl[] = {
        5,      /* OFF-OFF-OFF  =  5 Sec  */
        10,     /* OFF-OFF-ON   = 10 Sec  */
        30,     /* OFF-ON-OFF   = 30 Sec  */
        60,     /* OFF-ON-ON    =  1 Min  */
        300,    /* ON-OFF-OFF   =  5 Min  */
        600,    /* ON-OFF-ON    = 10 Min  */
        1800,   /* ON-ON-OFF    = 30 Min  */
        3600,   /* ON-ON-ON     =  1 hour */
};

/* 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 {
        /* save off the usb device pointer */
        struct usb_device       *udev;
        /* the interface for this device */
        struct usb_interface    *interface;

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

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

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

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

/* prevent races between open() and disconnect() */
static DEFINE_MUTEX(disconnect_mutex);

/* 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 = {
        .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 usb_pcwd_private *usb_pcwd =
                                (struct usb_pcwd_private *)urb->context;
        unsigned char *data = usb_pcwd->intr_buffer;
        struct device *dev = &usb_pcwd->interface->dev;
        int retval;

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

        dev_dbg(dev, "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)
                pr_err("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;

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

        buf = kmalloc(6, GFP_KERNEL);
        if (buf == NULL)
                return 0;

        /* 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 */

        dev_dbg(&usb_pcwd->interface->dev,
                "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, 6,
                        USB_COMMAND_TIMEOUT) != 6) {
                dev_dbg(&usb_pcwd->interface->dev,
                        "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;
        }

        kfree(buf);

        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)) {
                pr_err("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)) {
                pr_err("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;
}

static int usb_pcwd_get_timeleft(struct usb_pcwd_private *usb_pcwd,
                                                                int *time_left)
{
        unsigned char msb, lsb;

        /* Read the time that's left before rebooting */
        /* Note: if the board is not yet armed then we will read 0xFFFF */
        usb_pcwd_send_command(usb_pcwd, CMD_READ_WATCHDOG_TIMEOUT, &msb, &lsb);

        *time_left = (msb << 8) + lsb;

        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 long usb_pcwd_ioctl(struct file *file, unsigned int cmd,
                                                unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        int __user *p = argp;
        static const 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_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_KEEPALIVE:
                usb_pcwd_keepalive(usb_pcwd_device);
                return 0;

        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 through */

        case WDIOC_GETTIMEOUT:
                return put_user(heartbeat, p);

        case WDIOC_GETTIMELEFT:
        {
                int time_left;

                if (usb_pcwd_get_timeleft(usb_pcwd_device, &time_left))
                        return -EFAULT;

                return put_user(time_left, p);
        }

        default:
                return -ENOTTY;
        }
}

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 {
                pr_crit("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)
                usb_pcwd_stop(usb_pcwd_device); /* Turn the WDT off */

        return NOTIFY_DONE;
}

/*
 *      Kernel Interfaces
 */

static const struct file_operations usb_pcwd_fops = {
        .owner =        THIS_MODULE,
        .llseek =       no_llseek,
        .write =        usb_pcwd_write,
        .unlocked_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 const 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)
{
        usb_free_urb(usb_pcwd->intr_urb);
        if (usb_pcwd->intr_buffer != NULL)
                usb_free_coherent(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;
        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) {
                pr_err("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)) {
                pr_err("The device isn't a Human Interface Device\n");
                return -ENODEV;
        }

        if (iface_desc->desc.bNumEndpoints < 1)
                return -ENODEV;

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

        if (!usb_endpoint_is_int_in(endpoint)) {
                /* we didn't find a Interrupt endpoint with direction IN */
                pr_err("Couldn't find an INTR & IN endpoint\n");
                return -ENODEV;
        }

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

        /* allocate memory for our device and initialize it */
        usb_pcwd = kzalloc(sizeof(struct usb_pcwd_private), GFP_KERNEL);
        if (usb_pcwd == NULL)
                goto error;

        usb_pcwd_device = usb_pcwd;

        mutex_init(&usb_pcwd->mtx);
        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 */
        usb_pcwd->intr_buffer = usb_alloc_coherent(udev, usb_pcwd->intr_size,
                                        GFP_ATOMIC, &usb_pcwd->intr_dma);
        if (!usb_pcwd->intr_buffer) {
                pr_err("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)
                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)) {
                pr_err("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>");

        pr_info("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);

        pr_info("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"));

        /* If heartbeat = 0 then we use the heartbeat from the dip-switches */
        if (heartbeat == 0)
                heartbeat = heartbeat_tbl[(option_switches & 0x07)];

        /* 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);
                pr_info("heartbeat value must be 0<heartbeat<65536, using %d\n",
                        WATCHDOG_HEARTBEAT);
        }

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

        retval = misc_register(&usb_pcwd_temperature_miscdev);
        if (retval != 0) {
                pr_err("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) {
                pr_err("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);

        pr_info("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:
        if (usb_pcwd)
                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() */
        mutex_lock(&disconnect_mutex);

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

        mutex_lock(&usb_pcwd->mtx);

        /* 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);

        mutex_unlock(&usb_pcwd->mtx);

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

        cards_found--;

        mutex_unlock(&disconnect_mutex);

        pr_info("USB PC Watchdog disconnected\n");
}

module_usb_driver(usb_pcwd_driver);