/*
* usb class driver info in order to get a minor number from the usb core,
* and to have the device registered with the driver core
*/
static struct usb_class_driver skel_class = {
.name = "skel%d",
.fops = &skel_fops,
.minor_base = USB_SKEL_MINOR_BASE,
};

static int skel_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
struct usb_skel *dev;
struct usb_host_interface *iface_desc;
struct usb_endpoint_descriptor *endpoint;
size_t buffer_size;
int i;
int retval = -ENOMEM;

/* allocate memory for our device state and initialize it */
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev) {
err("Out of memory");
goto error;
}
kref_init(&dev->kref);
sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
mutex_init(&dev->io_mutex);
spin_lock_init(&dev->err_lock);
init_usb_anchor(&dev->submitted);
init_completion(&dev->bulk_in_completion);

dev->udev = usb_get_dev(interface_to_usbdev(interface));
dev->interface = interface;

/* set up the endpoint information */
/* use only the first bulk-in and bulk-out endpoints */
iface_desc = interface->cur_altsetting;
for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
endpoint = &iface_desc->endpoint[i].desc;

if (!dev->bulk_in_endpointAddr &&
usb_endpoint_is_bulk_in(endpoint)) {
/* we found a bulk in endpoint */
buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
dev->bulk_in_size = buffer_size;
dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
if (!dev->bulk_in_buffer) {
err("Could not allocate bulk_in_buffer");
goto error;
}
dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!dev->bulk_in_urb) {
err("Could not allocate bulk_in_urb");
goto error;
}
}

if (!dev->bulk_out_endpointAddr &&
usb_endpoint_is_bulk_out(endpoint)) {
/* we found a bulk out endpoint */
dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
}
}
if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
err("Could not find both bulk-in and bulk-out endpoints");
goto error;
}

/* save our data pointer in this interface device */
usb_set_intfdata(interface, dev);

/* we can register the device now, as it is ready */
retval = usb_register_dev(interface, &skel_class);
if (retval) {
/* something prevented us from registering this driver */
err("Not able to get a minor for this device.");
usb_set_intfdata(interface, NULL);
goto error;
}

/* let the user know what node this device is now attached to */
dev_info(&interface->dev,
"USB Skeleton device now attached to USBSkel-%d",
interface->minor);
return 0;

error:
if (dev)
/* this frees allocated memory */
kref_put(&dev->kref, skel_delete);
return retval;
}