xref: /openbmc/linux/drivers/usb/misc/uss720.c (revision 57904291176fa16a981cefca5cbe1a0b50196792)

// SPDX-License-Identifier: GPL-2.0+
/*****************************************************************************/

/*
 *	uss720.c  --  USS720 USB Parport Cable.
 *
 *	Copyright (C) 1999, 2005, 2010
 *	    Thomas Sailer (t.sailer@alumni.ethz.ch)
 *
 *  Based on parport_pc.c
 *
 *  History:
 *   0.1  04.08.1999  Created
 *   0.2  07.08.1999  Some fixes mainly suggested by Tim Waugh
 *		      Interrupt handling currently disabled because
 *		      usb_request_irq crashes somewhere within ohci.c
 *		      for no apparent reason (that is for me, anyway)
 *		      ECP currently untested
 *   0.3  10.08.1999  fixing merge errors
 *   0.4  13.08.1999  Added Vendor/Product ID of Brad Hard's cable
 *   0.5  20.09.1999  usb_control_msg wrapper used
 *        Nov01.2000  usb_device_table support by Adam J. Richter
 *        08.04.2001  Identify version on module load.  gb
 *   0.6  02.09.2005  Fix "scheduling in interrupt" problem by making save/restore
 *                    context asynchronous
 *
 */

/*****************************************************************************/

#include <linux/module.h>
#include <linux/socket.h>
#include <linux/parport.h>
#include <linux/init.h>
#include <linux/usb.h>
#include <linux/delay.h>
#include <linux/completion.h>
#include <linux/kref.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>

#define DRIVER_AUTHOR "Thomas M. Sailer, t.sailer@alumni.ethz.ch"
#define DRIVER_DESC "USB Parport Cable driver for Cables using the Lucent Technologies USS720 Chip"

/* --------------------------------------------------------------------- */

struct parport_uss720_private {
	struct usb_device *usbdev;
	struct parport *pp;
	struct kref ref_count;
	__u8 reg[7];  /* USB registers */
	struct list_head asynclist;
	spinlock_t asynclock;
};

struct uss720_async_request {
	struct parport_uss720_private *priv;
	struct kref ref_count;
	struct list_head asynclist;
	struct completion compl;
	struct urb *urb;
	struct usb_ctrlrequest *dr;
	__u8 reg[7];
};

/* --------------------------------------------------------------------- */

static void destroy_priv(struct kref *kref)
{
	struct parport_uss720_private *priv = container_of(kref, struct parport_uss720_private, ref_count);

	dev_dbg(&priv->usbdev->dev, "destroying priv datastructure\n");
	usb_put_dev(priv->usbdev);
	priv->usbdev = NULL;
	kfree(priv);
}

static void destroy_async(struct kref *kref)
{
	struct uss720_async_request *rq = container_of(kref, struct uss720_async_request, ref_count);
	struct parport_uss720_private *priv = rq->priv;
	unsigned long flags;

	if (likely(rq->urb))
		usb_free_urb(rq->urb);
	kfree(rq->dr);
	spin_lock_irqsave(&priv->asynclock, flags);
	list_del_init(&rq->asynclist);
	spin_unlock_irqrestore(&priv->asynclock, flags);
	kfree(rq);
	kref_put(&priv->ref_count, destroy_priv);
}

/* --------------------------------------------------------------------- */

static void async_complete(struct urb *urb)
{
	struct uss720_async_request *rq;
	struct parport *pp;
	struct parport_uss720_private *priv;
	int status = urb->status;

	rq = urb->context;
	priv = rq->priv;
	pp = priv->pp;
	if (status) {
		dev_err(&urb->dev->dev, "async_complete: urb error %d\n",
			status);
	} else if (rq->dr->bRequest == 3) {
		memcpy(priv->reg, rq->reg, sizeof(priv->reg));
#if 0
		dev_dbg(&priv->usbdev->dev, "async_complete regs %7ph\n",
			priv->reg);
#endif
		/* if nAck interrupts are enabled and we have an interrupt, call the interrupt procedure */
		if (rq->reg[2] & rq->reg[1] & 0x10 && pp)
			parport_generic_irq(pp);
	}
	complete(&rq->compl);
	kref_put(&rq->ref_count, destroy_async);
}

static struct uss720_async_request *submit_async_request(struct parport_uss720_private *priv,
							 __u8 request, __u8 requesttype, __u16 value, __u16 index,
							 gfp_t mem_flags)
{
	struct usb_device *usbdev;
	struct uss720_async_request *rq;
	unsigned long flags;
	int ret;

	if (!priv)
		return NULL;
	usbdev = priv->usbdev;
	if (!usbdev)
		return NULL;
	rq = kzalloc(sizeof(struct uss720_async_request), mem_flags);
	if (!rq)
		return NULL;
	kref_init(&rq->ref_count);
	INIT_LIST_HEAD(&rq->asynclist);
	init_completion(&rq->compl);
	kref_get(&priv->ref_count);
	rq->priv = priv;
	rq->urb = usb_alloc_urb(0, mem_flags);
	if (!rq->urb) {
		kref_put(&rq->ref_count, destroy_async);
		return NULL;
	}
	rq->dr = kmalloc(sizeof(*rq->dr), mem_flags);
	if (!rq->dr) {
		kref_put(&rq->ref_count, destroy_async);
		return NULL;
	}
	rq->dr->bRequestType = requesttype;
	rq->dr->bRequest = request;
	rq->dr->wValue = cpu_to_le16(value);
	rq->dr->wIndex = cpu_to_le16(index);
	rq->dr->wLength = cpu_to_le16((request == 3) ? sizeof(rq->reg) : 0);
	usb_fill_control_urb(rq->urb, usbdev, (requesttype & 0x80) ? usb_rcvctrlpipe(usbdev, 0) : usb_sndctrlpipe(usbdev, 0),
			     (unsigned char *)rq->dr,
			     (request == 3) ? rq->reg : NULL, (request == 3) ? sizeof(rq->reg) : 0, async_complete, rq);
	/* rq->urb->transfer_flags |= URB_ASYNC_UNLINK; */
	spin_lock_irqsave(&priv->asynclock, flags);
	list_add_tail(&rq->asynclist, &priv->asynclist);
	spin_unlock_irqrestore(&priv->asynclock, flags);
	kref_get(&rq->ref_count);
	ret = usb_submit_urb(rq->urb, mem_flags);
	if (!ret)
		return rq;
	destroy_async(&rq->ref_count);
	dev_err(&usbdev->dev, "submit_async_request submit_urb failed with %d\n", ret);
	return NULL;
}

static unsigned int kill_all_async_requests_priv(struct parport_uss720_private *priv)
{
	struct uss720_async_request *rq;
	unsigned long flags;
	unsigned int ret = 0;

	spin_lock_irqsave(&priv->asynclock, flags);
	list_for_each_entry(rq, &priv->asynclist, asynclist) {
		usb_unlink_urb(rq->urb);
		ret++;
	}
	spin_unlock_irqrestore(&priv->asynclock, flags);
	return ret;
}

/* --------------------------------------------------------------------- */

static int get_1284_register(struct parport *pp, unsigned char reg, unsigned char *val, gfp_t mem_flags)
{
	struct parport_uss720_private *priv;
	struct uss720_async_request *rq;
	static const unsigned char regindex[9] = {
		4, 0, 1, 5, 5, 0, 2, 3, 6
	};
	int ret;

	if (!pp)
		return -EIO;
	priv = pp->private_data;
	rq = submit_async_request(priv, 3, 0xc0, ((unsigned int)reg) << 8, 0, mem_flags);
	if (!rq) {
		dev_err(&priv->usbdev->dev, "get_1284_register(%u) failed",
			(unsigned int)reg);
		return -EIO;
	}
	if (!val) {
		kref_put(&rq->ref_count, destroy_async);
		return 0;
	}
	if (wait_for_completion_timeout(&rq->compl, HZ)) {
		ret = rq->urb->status;
		*val = priv->reg[(reg >= 9) ? 0 : regindex[reg]];
		if (ret)
			printk(KERN_WARNING "get_1284_register: "
			       "usb error %d\n", ret);
		kref_put(&rq->ref_count, destroy_async);
		return ret;
	}
	printk(KERN_WARNING "get_1284_register timeout\n");
	kill_all_async_requests_priv(priv);
	return -EIO;
}

static int set_1284_register(struct parport *pp, unsigned char reg, unsigned char val, gfp_t mem_flags)
{
	struct parport_uss720_private *priv;
	struct uss720_async_request *rq;

	if (!pp)
		return -EIO;
	priv = pp->private_data;
	rq = submit_async_request(priv, 4, 0x40, (((unsigned int)reg) << 8) | val, 0, mem_flags);
	if (!rq) {
		dev_err(&priv->usbdev->dev, "set_1284_register(%u,%u) failed",
			(unsigned int)reg, (unsigned int)val);
		return -EIO;
	}
	kref_put(&rq->ref_count, destroy_async);
	return 0;
}

/* --------------------------------------------------------------------- */

/* ECR modes */
#define ECR_SPP 00
#define ECR_PS2 01
#define ECR_PPF 02
#define ECR_ECP 03
#define ECR_EPP 04

/* Safely change the mode bits in the ECR */
static int change_mode(struct parport *pp, int m)
{
	struct parport_uss720_private *priv = pp->private_data;
	int mode;
	__u8 reg;

	if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
		return -EIO;
	/* Bits <7:5> contain the mode. */
	mode = (priv->reg[2] >> 5) & 0x7;
	if (mode == m)
		return 0;
	/* We have to go through mode 000 or 001 */
	if (mode > ECR_PS2 && m > ECR_PS2)
		if (change_mode(pp, ECR_PS2))
			return -EIO;

	if (m <= ECR_PS2 && !(priv->reg[1] & 0x20)) {
		/* This mode resets the FIFO, so we may
		 * have to wait for it to drain first. */
		unsigned long expire = jiffies + pp->physport->cad->timeout;
		switch (mode) {
		case ECR_PPF: /* Parallel Port FIFO mode */
		case ECR_ECP: /* ECP Parallel Port mode */
			/* Poll slowly. */
			for (;;) {
				if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
					return -EIO;
				if (priv->reg[2] & 0x01)
					break;
				if (time_after_eq (jiffies, expire))
					/* The FIFO is stuck. */
					return -EBUSY;
				msleep_interruptible(10);
				if (signal_pending (current))
					break;
			}
		}
	}
	/* Set the mode. */
	if (set_1284_register(pp, 6, m << 5, GFP_KERNEL))
		return -EIO;
	if (get_1284_register(pp, 6, &reg, GFP_KERNEL))
		return -EIO;
	return 0;
}

/*
 * Clear TIMEOUT BIT in EPP MODE
 */
static int clear_epp_timeout(struct parport *pp)
{
	unsigned char stat;

	if (get_1284_register(pp, 1, &stat, GFP_KERNEL))
		return 1;
	return stat & 1;
}

/*
 * Access functions.
 */
#if 0
static int uss720_irq(int usbstatus, void *buffer, int len, void *dev_id)
{
	struct parport *pp = (struct parport *)dev_id;
	struct parport_uss720_private *priv = pp->private_data;

	if (usbstatus != 0 || len < 4 || !buffer)
		return 1;
	memcpy(priv->reg, buffer, 4);
	/* if nAck interrupts are enabled and we have an interrupt, call the interrupt procedure */
	if (priv->reg[2] & priv->reg[1] & 0x10)
		parport_generic_irq(pp);
	return 1;
}
#endif

static void parport_uss720_write_data(struct parport *pp, unsigned char d)
{
	set_1284_register(pp, 0, d, GFP_KERNEL);
}

static unsigned char parport_uss720_read_data(struct parport *pp)
{
	unsigned char ret;

	if (get_1284_register(pp, 0, &ret, GFP_KERNEL))
		return 0;
	return ret;
}

static void parport_uss720_write_control(struct parport *pp, unsigned char d)
{
	struct parport_uss720_private *priv = pp->private_data;

	d = (d & 0xf) | (priv->reg[1] & 0xf0);
	if (set_1284_register(pp, 2, d, GFP_KERNEL))
		return;
	priv->reg[1] = d;
}

static unsigned char parport_uss720_read_control(struct parport *pp)
{
	struct parport_uss720_private *priv = pp->private_data;
	return priv->reg[1] & 0xf; /* Use soft copy */
}

static unsigned char parport_uss720_frob_control(struct parport *pp, unsigned char mask, unsigned char val)
{
	struct parport_uss720_private *priv = pp->private_data;
	unsigned char d;

	mask &= 0x0f;
	val &= 0x0f;
	d = (priv->reg[1] & (~mask)) ^ val;
	if (set_1284_register(pp, 2, d, GFP_ATOMIC))
		return 0;
	priv->reg[1] = d;
	return d & 0xf;
}

static unsigned char parport_uss720_read_status(struct parport *pp)
{
	unsigned char ret;

	if (get_1284_register(pp, 1, &ret, GFP_ATOMIC))
		return 0;
	return ret & 0xf8;
}

static void parport_uss720_disable_irq(struct parport *pp)
{
	struct parport_uss720_private *priv = pp->private_data;
	unsigned char d;

	d = priv->reg[1] & ~0x10;
	if (set_1284_register(pp, 2, d, GFP_KERNEL))
		return;
	priv->reg[1] = d;
}

static void parport_uss720_enable_irq(struct parport *pp)
{
	struct parport_uss720_private *priv = pp->private_data;
	unsigned char d;

	d = priv->reg[1] | 0x10;
	if (set_1284_register(pp, 2, d, GFP_KERNEL))
		return;
	priv->reg[1] = d;
}

static void parport_uss720_data_forward (struct parport *pp)
{
	struct parport_uss720_private *priv = pp->private_data;
	unsigned char d;

	d = priv->reg[1] & ~0x20;
	if (set_1284_register(pp, 2, d, GFP_KERNEL))
		return;
	priv->reg[1] = d;
}

static void parport_uss720_data_reverse (struct parport *pp)
{
	struct parport_uss720_private *priv = pp->private_data;
	unsigned char d;

	d = priv->reg[1] | 0x20;
	if (set_1284_register(pp, 2, d, GFP_KERNEL))
		return;
	priv->reg[1] = d;
}

static void parport_uss720_init_state(struct pardevice *dev, struct parport_state *s)
{
	s->u.pc.ctr = 0xc | (dev->irq_func ? 0x10 : 0x0);
	s->u.pc.ecr = 0x24;
}

static void parport_uss720_save_state(struct parport *pp, struct parport_state *s)
{
	struct parport_uss720_private *priv = pp->private_data;

#if 0
	if (get_1284_register(pp, 2, NULL, GFP_ATOMIC))
		return;
#endif
	s->u.pc.ctr = priv->reg[1];
	s->u.pc.ecr = priv->reg[2];
}

static void parport_uss720_restore_state(struct parport *pp, struct parport_state *s)
{
	struct parport_uss720_private *priv = pp->private_data;

	set_1284_register(pp, 2, s->u.pc.ctr, GFP_ATOMIC);
	set_1284_register(pp, 6, s->u.pc.ecr, GFP_ATOMIC);
	get_1284_register(pp, 2, NULL, GFP_ATOMIC);
	priv->reg[1] = s->u.pc.ctr;
	priv->reg[2] = s->u.pc.ecr;
}

static size_t parport_uss720_epp_read_data(struct parport *pp, void *buf, size_t length, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	size_t got = 0;

	if (change_mode(pp, ECR_EPP))
		return 0;
	for (; got < length; got++) {
		if (get_1284_register(pp, 4, (char *)buf, GFP_KERNEL))
			break;
		buf++;
		if (priv->reg[0] & 0x01) {
			clear_epp_timeout(pp);
			break;
		}
	}
	change_mode(pp, ECR_PS2);
	return got;
}

static size_t parport_uss720_epp_write_data(struct parport *pp, const void *buf, size_t length, int flags)
{
#if 0
	struct parport_uss720_private *priv = pp->private_data;
	size_t written = 0;

	if (change_mode(pp, ECR_EPP))
		return 0;
	for (; written < length; written++) {
		if (set_1284_register(pp, 4, (char *)buf, GFP_KERNEL))
			break;
		((char*)buf)++;
		if (get_1284_register(pp, 1, NULL, GFP_KERNEL))
			break;
		if (priv->reg[0] & 0x01) {
			clear_epp_timeout(pp);
			break;
		}
	}
	change_mode(pp, ECR_PS2);
	return written;
#else
	struct parport_uss720_private *priv = pp->private_data;
	struct usb_device *usbdev = priv->usbdev;
	int rlen = 0;
	int i;

	if (!usbdev)
		return 0;
	if (change_mode(pp, ECR_EPP))
		return 0;
	i = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, 1), (void *)buf, length, &rlen, 20000);
	if (i)
		printk(KERN_ERR "uss720: sendbulk ep 1 buf %p len %zu rlen %u\n", buf, length, rlen);
	change_mode(pp, ECR_PS2);
	return rlen;
#endif
}

static size_t parport_uss720_epp_read_addr(struct parport *pp, void *buf, size_t length, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	size_t got = 0;

	if (change_mode(pp, ECR_EPP))
		return 0;
	for (; got < length; got++) {
		if (get_1284_register(pp, 3, (char *)buf, GFP_KERNEL))
			break;
		buf++;
		if (priv->reg[0] & 0x01) {
			clear_epp_timeout(pp);
			break;
		}
	}
	change_mode(pp, ECR_PS2);
	return got;
}

static size_t parport_uss720_epp_write_addr(struct parport *pp, const void *buf, size_t length, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	size_t written = 0;

	if (change_mode(pp, ECR_EPP))
		return 0;
	for (; written < length; written++) {
		if (set_1284_register(pp, 3, *(char *)buf, GFP_KERNEL))
			break;
		buf++;
		if (get_1284_register(pp, 1, NULL, GFP_KERNEL))
			break;
		if (priv->reg[0] & 0x01) {
			clear_epp_timeout(pp);
			break;
		}
	}
	change_mode(pp, ECR_PS2);
	return written;
}

static size_t parport_uss720_ecp_write_data(struct parport *pp, const void *buffer, size_t len, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	struct usb_device *usbdev = priv->usbdev;
	int rlen = 0;
	int i;

	if (!usbdev)
		return 0;
	if (change_mode(pp, ECR_ECP))
		return 0;
	i = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, 1), (void *)buffer, len, &rlen, 20000);
	if (i)
		printk(KERN_ERR "uss720: sendbulk ep 1 buf %p len %zu rlen %u\n", buffer, len, rlen);
	change_mode(pp, ECR_PS2);
	return rlen;
}

static size_t parport_uss720_ecp_read_data(struct parport *pp, void *buffer, size_t len, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	struct usb_device *usbdev = priv->usbdev;
	int rlen = 0;
	int i;

	if (!usbdev)
		return 0;
	if (change_mode(pp, ECR_ECP))
		return 0;
	i = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, 2), buffer, len, &rlen, 20000);
	if (i)
		printk(KERN_ERR "uss720: recvbulk ep 2 buf %p len %zu rlen %u\n", buffer, len, rlen);
	change_mode(pp, ECR_PS2);
	return rlen;
}

static size_t parport_uss720_ecp_write_addr(struct parport *pp, const void *buffer, size_t len, int flags)
{
	size_t written = 0;

	if (change_mode(pp, ECR_ECP))
		return 0;
	for (; written < len; written++) {
		if (set_1284_register(pp, 5, *(char *)buffer, GFP_KERNEL))
			break;
		buffer++;
	}
	change_mode(pp, ECR_PS2);
	return written;
}

static size_t parport_uss720_write_compat(struct parport *pp, const void *buffer, size_t len, int flags)
{
	struct parport_uss720_private *priv = pp->private_data;
	struct usb_device *usbdev = priv->usbdev;
	int rlen = 0;
	int i;

	if (!usbdev)
		return 0;
	if (change_mode(pp, ECR_PPF))
		return 0;
	i = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, 1), (void *)buffer, len, &rlen, 20000);
	if (i)
		printk(KERN_ERR "uss720: sendbulk ep 1 buf %p len %zu rlen %u\n", buffer, len, rlen);
	change_mode(pp, ECR_PS2);
	return rlen;
}

/* --------------------------------------------------------------------- */

static struct parport_operations parport_uss720_ops =
{
	.owner =		THIS_MODULE,
	.write_data =		parport_uss720_write_data,
	.read_data =		parport_uss720_read_data,

	.write_control =	parport_uss720_write_control,
	.read_control =		parport_uss720_read_control,
	.frob_control =		parport_uss720_frob_control,

	.read_status =		parport_uss720_read_status,

	.enable_irq =		parport_uss720_enable_irq,
	.disable_irq =		parport_uss720_disable_irq,

	.data_forward =		parport_uss720_data_forward,
	.data_reverse =		parport_uss720_data_reverse,

	.init_state =		parport_uss720_init_state,
	.save_state =		parport_uss720_save_state,
	.restore_state =	parport_uss720_restore_state,

	.epp_write_data =	parport_uss720_epp_write_data,
	.epp_read_data =	parport_uss720_epp_read_data,
	.epp_write_addr =	parport_uss720_epp_write_addr,
	.epp_read_addr =	parport_uss720_epp_read_addr,

	.ecp_write_data =	parport_uss720_ecp_write_data,
	.ecp_read_data =	parport_uss720_ecp_read_data,
	.ecp_write_addr =	parport_uss720_ecp_write_addr,

	.compat_write_data =	parport_uss720_write_compat,
	.nibble_read_data =	parport_ieee1284_read_nibble,
	.byte_read_data =	parport_ieee1284_read_byte,
};

/* --------------------------------------------------------------------- */

static int uss720_probe(struct usb_interface *intf,
			const struct usb_device_id *id)
{
	struct usb_device *usbdev = usb_get_dev(interface_to_usbdev(intf));
	struct usb_host_interface *interface;
	struct usb_endpoint_descriptor *epd;
	struct parport_uss720_private *priv;
	struct parport *pp;
	unsigned char reg;
	int ret;

	dev_dbg(&intf->dev, "probe: vendor id 0x%x, device id 0x%x\n",
		le16_to_cpu(usbdev->descriptor.idVendor),
		le16_to_cpu(usbdev->descriptor.idProduct));

	/* our known interfaces have 3 alternate settings */
	if (intf->num_altsetting != 3) {
		usb_put_dev(usbdev);
		return -ENODEV;
	}
	ret = usb_set_interface(usbdev, intf->altsetting->desc.bInterfaceNumber, 2);
	dev_dbg(&intf->dev, "set interface result %d\n", ret);

	interface = intf->cur_altsetting;

	if (interface->desc.bNumEndpoints < 3) {
		usb_put_dev(usbdev);
		return -ENODEV;
	}

	/*
	 * Allocate parport interface
	 */
	priv = kzalloc(sizeof(struct parport_uss720_private), GFP_KERNEL);
	if (!priv) {
		usb_put_dev(usbdev);
		return -ENOMEM;
	}
	priv->pp = NULL;
	priv->usbdev = usbdev;
	kref_init(&priv->ref_count);
	spin_lock_init(&priv->asynclock);
	INIT_LIST_HEAD(&priv->asynclist);
	pp = parport_register_port(0, PARPORT_IRQ_NONE, PARPORT_DMA_NONE, &parport_uss720_ops);
	if (!pp) {
		printk(KERN_WARNING "uss720: could not register parport\n");
		goto probe_abort;
	}

	priv->pp = pp;
	pp->private_data = priv;
	pp->modes = PARPORT_MODE_PCSPP | PARPORT_MODE_TRISTATE | PARPORT_MODE_EPP | PARPORT_MODE_ECP | PARPORT_MODE_COMPAT;

	/* set the USS720 control register to manual mode, no ECP compression, enable all ints */
	set_1284_register(pp, 7, 0x00, GFP_KERNEL);
	set_1284_register(pp, 6, 0x30, GFP_KERNEL);  /* PS/2 mode */
	set_1284_register(pp, 2, 0x0c, GFP_KERNEL);

	/* The Belkin F5U002 Rev 2 P80453-B USB parallel port adapter shares the
	 * device ID 050d:0002 with some other device that works with this
	 * driver, but it itself does not. Detect and handle the bad cable
	 * here. */
	ret = get_1284_register(pp, 0, &reg, GFP_KERNEL);
	dev_dbg(&intf->dev, "reg: %7ph\n", priv->reg);
	if (ret < 0)
		return ret;

	ret = usb_find_last_int_in_endpoint(interface, &epd);
	if (!ret) {
		dev_dbg(&intf->dev, "epaddr %d interval %d\n",
				epd->bEndpointAddress, epd->bInterval);
	}
	parport_announce_port(pp);

	usb_set_intfdata(intf, pp);
	return 0;

probe_abort:
	kill_all_async_requests_priv(priv);
	kref_put(&priv->ref_count, destroy_priv);
	return -ENODEV;
}

static void uss720_disconnect(struct usb_interface *intf)
{
	struct parport *pp = usb_get_intfdata(intf);
	struct parport_uss720_private *priv;

	dev_dbg(&intf->dev, "disconnect\n");
	usb_set_intfdata(intf, NULL);
	if (pp) {
		priv = pp->private_data;
		priv->pp = NULL;
		dev_dbg(&intf->dev, "parport_remove_port\n");
		parport_remove_port(pp);
		parport_put_port(pp);
		kill_all_async_requests_priv(priv);
		kref_put(&priv->ref_count, destroy_priv);
	}
	dev_dbg(&intf->dev, "disconnect done\n");
}

/* table of cables that work through this driver */
static const struct usb_device_id uss720_table[] = {
	{ USB_DEVICE(0x047e, 0x1001) },
	{ USB_DEVICE(0x04b8, 0x0002) },
	{ USB_DEVICE(0x04b8, 0x0003) },
	{ USB_DEVICE(0x050d, 0x0002) },
	{ USB_DEVICE(0x050d, 0x1202) },
	{ USB_DEVICE(0x0557, 0x2001) },
	{ USB_DEVICE(0x05ab, 0x0002) },
	{ USB_DEVICE(0x06c6, 0x0100) },
	{ USB_DEVICE(0x0729, 0x1284) },
	{ USB_DEVICE(0x1293, 0x0002) },
	{ }						/* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, uss720_table);


static struct usb_driver uss720_driver = {
	.name =		"uss720",
	.probe =	uss720_probe,
	.disconnect =	uss720_disconnect,
	.id_table =	uss720_table,
};

/* --------------------------------------------------------------------- */

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

static int __init uss720_init(void)
{
	int retval;
	retval = usb_register(&uss720_driver);
	if (retval)
		goto out;

	printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_DESC "\n");
	printk(KERN_INFO KBUILD_MODNAME ": NOTE: this is a special purpose "
	       "driver to allow nonstandard\n");
	printk(KERN_INFO KBUILD_MODNAME ": protocols (eg. bitbang) over "
	       "USS720 usb to parallel cables\n");
	printk(KERN_INFO KBUILD_MODNAME ": If you just want to connect to a "
	       "printer, use usblp instead\n");
out:
	return retval;
}

static void __exit uss720_cleanup(void)
{
	usb_deregister(&uss720_driver);
}

module_init(uss720_init);
module_exit(uss720_cleanup);

/* --------------------------------------------------------------------- */