/*
 * Written by Oron Peled <oron@actcom.co.il>
 * Copyright (C) 2004-2006, Xorcom
 *
 * All rights reserved.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/delay.h>	/* for udelay */
#include <linux/seq_file.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/timex.h>
#include <linux/proc_fs.h>
#include <linux/usb.h>
#include "xpd.h"
#include "xproto.h"
#include "xbus-core.h"
#include "xframe_queue.h"
#ifdef	DEBUG
#include "card_fxs.h"
#include "card_fxo.h"
#endif
#include "parport_debug.h"

static const char rcsid[] = "$Id$";

/* must be before dahdi_debug.h */
static DEF_PARM(int, debug, 0, 0644, "Print DBG statements");
static DEF_PARM(int, usb1, 0, 0644, "Allow using USB 1.1 interfaces");
static DEF_PARM(uint, tx_sluggish, 2000, 0644, "A sluggish transmit (usec)");
static DEF_PARM(uint, drop_pcm_after, 6, 0644,
		"Number of consecutive tx_sluggish to start dropping PCM");
static DEF_PARM(uint, sluggish_pcm_keepalive, 50, 0644,
		"During sluggish -- Keep-alive PCM (1 every #)");

#include "dahdi_debug.h"

#define	XUSB_PRINTK(level, xusb, fmt, ...)	\
	printk(KERN_ ## level "%s-%s: xusb-%d (%s) [%s]: " fmt, #level,	\
		THIS_MODULE->name, (xusb)->index, xusb->path, \
		xusb->serial, ## __VA_ARGS__)

#define	XUSB_DBG(bits, xusb, fmt, ...)	\
	((void)((debug & (DBG_ ## bits)) && XUSB_PRINTK(DEBUG, \
		xusb, "%s: " fmt, __func__, ## __VA_ARGS__)))
#define	XUSB_ERR(xusb, fmt, ...) \
	XUSB_PRINTK(ERR, xusb, fmt, ## __VA_ARGS__)
#define	XUSB_NOTICE(xusb, fmt, ...) \
	XUSB_PRINTK(NOTICE, xusb, fmt, ## __VA_ARGS__)
#define	XUSB_INFO(xusb, fmt, ...) \
	XUSB_PRINTK(INFO, xusb, fmt, ## __VA_ARGS__)

/* Get a minor range for your devices from the usb maintainer */
#define USB_SKEL_MINOR_BASE	192

#ifdef CONFIG_PROC_FS
#define	PROC_USBXPP_SUMMARY	"xpp_usb"
#endif

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34)
#define usb_alloc_coherent(dev, size, mem_flags, dma) \
	usb_buffer_alloc(dev, size, mem_flags, dma)
#define usb_free_coherent(dev, size, addr, dma) \
	usb_buffer_free(dev, size, addr, dma)
#endif

#ifdef	DEBUG_PCM_TIMING
static cycles_t stamp_last_pcm_read;
static cycles_t accumulate_diff;
#endif

struct xusb_model_info;

struct xusb_endpoint {
	int ep_addr;
	int max_size;
	usb_complete_t callback;
};

enum xusb_dir {
	XUSB_RECV = 0,
	XUSB_SEND = 1,
};

static __must_check int xframe_send_pcm(xbus_t *xbus, xframe_t *xframe);
static __must_check int xframe_send_cmd(xbus_t *xbus, xframe_t *xframe);
static __must_check xframe_t *alloc_xframe(xbus_t *xbus, gfp_t flags);
static void free_xframe(xbus_t *xbus, xframe_t *frm);

static struct xbus_ops xusb_ops = {
	.xframe_send_pcm = xframe_send_pcm,
	.xframe_send_cmd = xframe_send_cmd,
	.alloc_xframe = alloc_xframe,
	.free_xframe = free_xframe,
};

enum {
	XUSB_N_RX_FRAMES,
	XUSB_N_TX_FRAMES,
	XUSB_N_RX_ERRORS,
	XUSB_N_TX_ERRORS,
	XUSB_N_RX_DROPS,
	XUSB_N_TX_DROPS,
	XUSB_N_RCV_ZERO_LEN,
};

#define	XUSB_COUNTER(xusb, counter)	((xusb)->counters[XUSB_N_ ## counter])

#define	C_(x)	[ XUSB_N_ ## x ] = { #x }

static struct xusb_counters {
	char *name;
} xusb_counters[] = {
	C_(RX_FRAMES),
	C_(TX_FRAMES),
	C_(RX_ERRORS),
	C_(TX_ERRORS),
	C_(RX_DROPS),
	C_(TX_DROPS),
	C_(RCV_ZERO_LEN),
};

#undef C_

#define	XUSB_COUNTER_MAX	ARRAY_SIZE(xusb_counters)

#define	MAX_PENDING_WRITES	100

static KMEM_CACHE_T *xusb_cache;

typedef struct xusb xusb_t;

/*
 * A uframe is our low level representation of a frame.
 *
 * It contains the metadata for the usb stack (a urb)
 * and the metadata for the xbus-core (an xframe)
 * as well as pointing to the data (transfer_buffer, transfer_buffer_length)
 * directionality (send/receive) and ownership (xusb).
 */
struct uframe {
	unsigned long uframe_magic;
#define	UFRAME_MAGIC	654321L
	struct urb urb;
	xframe_t xframe;
	size_t transfer_buffer_length;
	void *transfer_buffer;	/* max XFRAME_DATASIZE */
	xusb_t *xusb;
};

#define	urb_to_uframe(urb) \
		container_of(urb, struct uframe, urb)
#define	xframe_to_uframe(xframe) \
		container_of(xframe, struct uframe, xframe)
#define	xusb_of(xbus) \
		((xusb_t *)((xbus)->transport.priv))

#define	USEC_BUCKET		100	/* usec */
#define	NUM_BUCKETS		15
#define	BUCKET_START		(500/USEC_BUCKET)	/* skip uninteresting */

/*
 * USB XPP Bus (a USB Device)
 */
struct xusb {
	uint xbus_num;
	struct usb_device *udev;	/* save off the usb device pointer */
	struct usb_interface *interface; /* the interface for this device */
	unsigned char minor;	/* the starting minor number for this device */
	uint index;
	char path[XBUS_DESCLEN];	/* a unique path */

	struct xusb_model_info *model_info;
	struct xusb_endpoint endpoints[2];	/* RECV/SEND endpoints */

	int present;		/* if the device is not disconnected */
	atomic_t pending_writes;	/* submited but not out yet */
	atomic_t pending_reads;	/* submited but not in yet */
	struct semaphore sem;	/* locks this structure */
	int counters[XUSB_COUNTER_MAX];

	/* metrics */
	ktime_t last_tx;
	unsigned int max_tx_delay;
	uint usb_tx_delay[NUM_BUCKETS];
	uint sluggish_debounce;
	bool drop_pcm;	/* due to sluggishness */
	atomic_t usb_sluggish_count;

	const char *manufacturer;
	const char *product;
	const char *serial;
	const char *interface_name;

};

static DEFINE_SPINLOCK(xusb_lock);
static xusb_t *xusb_array[MAX_BUSES] = { };

static unsigned bus_count;

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

static void xpp_send_callback(struct urb *urb);
static void xpp_receive_callback(struct urb *urb);
static int xusb_probe(struct usb_interface *interface,
		      const struct usb_device_id *id);
static void xusb_disconnect(struct usb_interface *interface);
#ifdef	CONFIG_PROC_FS
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
static const struct proc_ops xusb_read_proc_ops;
#else
static const struct file_operations xusb_read_proc_ops;
#endif
#endif

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

/*
 * Updates the urb+xframe metadata from the uframe information.
 */
static void uframe_recompute(struct uframe *uframe, enum xusb_dir dir)
{
	struct urb *urb = &uframe->urb;
	xusb_t *xusb = uframe->xusb;
	struct usb_device *udev = xusb->udev;
	struct xusb_endpoint *xusb_ep = &xusb->endpoints[dir];
	unsigned int ep_addr = xusb_ep->ep_addr;
	usb_complete_t urb_cb = xusb_ep->callback;
	unsigned int epnum = ep_addr & USB_ENDPOINT_NUMBER_MASK;
	int pipe = usb_pipein(ep_addr)
	    ? usb_rcvbulkpipe(udev, epnum)
	    : usb_sndbulkpipe(udev, epnum);

	BUG_ON(uframe->uframe_magic != UFRAME_MAGIC);
	usb_fill_bulk_urb(urb, udev, pipe, uframe->transfer_buffer,
			  uframe->transfer_buffer_length, urb_cb, uframe);
	urb->transfer_flags = (URB_NO_TRANSFER_DMA_MAP);
}

static xframe_t *alloc_xframe(xbus_t *xbus, gfp_t gfp_flags)
{
	struct uframe *uframe;
	xusb_t *xusb;
	void *p;
	int size;
	static int rate_limit;

	BUG_ON(!xbus);
	xusb = xusb_of(xbus);
	BUG_ON(!xusb);
	if (!xusb->present) {
		if ((rate_limit++ % 1003) == 0)
			XUSB_ERR(xusb,
				"abort allocations during "
				"device disconnect (%d)\n",
				rate_limit);
		return NULL;
	}
	size =
	    min(xusb->endpoints[XUSB_SEND].max_size,
		xusb->endpoints[XUSB_RECV].max_size);
	uframe = kmem_cache_alloc(xusb_cache, gfp_flags);
	if (!uframe) {
		if ((rate_limit++ % 1003) == 0)
			XUSB_ERR(xusb, "frame allocation failed (%d)\n",
				 rate_limit);
		return NULL;
	}
	usb_init_urb(&uframe->urb);
	p = usb_alloc_coherent(xusb->udev, size, gfp_flags,
			       &uframe->urb.transfer_dma);
	if (!p) {
		if ((rate_limit++ % 1003) == 0)
			XUSB_ERR(xusb, "buffer allocation failed (%d)\n",
				 rate_limit);
		kmem_cache_free(xusb_cache, uframe);
		return NULL;
	}
	uframe->uframe_magic = UFRAME_MAGIC;
	uframe->transfer_buffer_length = size;
	uframe->transfer_buffer = p;
	uframe->xusb = xusb;
	xframe_init(xbus, &uframe->xframe, uframe->transfer_buffer,
		    uframe->transfer_buffer_length, uframe);
	return &uframe->xframe;
}

static void free_xframe(xbus_t *xbus, xframe_t *xframe)
{
	struct uframe *uframe = xframe_to_uframe(xframe);
	struct urb *urb = &uframe->urb;

	BUG_ON(xbus->transport.priv != uframe->xusb);
	//XUSB_INFO(uframe->xusb, "frame_free\n");
	usb_free_coherent(urb->dev, uframe->transfer_buffer_length,
			  urb->transfer_buffer, urb->transfer_dma);
	memset(uframe, 0, sizeof(*uframe));
	kmem_cache_free(xusb_cache, uframe);
}

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

/*
 * Actuall frame sending -- both PCM and commands.
 */
static int do_send_xframe(xbus_t *xbus, xframe_t *xframe)
{
	struct urb *urb;
	xusb_t *xusb;
	int ret = 0;
	struct uframe *uframe;

	BUG_ON(!xframe);
	BUG_ON(xframe->xframe_magic != XFRAME_MAGIC);
	xusb = xusb_of(xbus);
	BUG_ON(!xusb);
	if (!xusb->present) {
		static int rate_limit;

		if ((rate_limit++ % 1003) == 0)
			XUSB_ERR(xusb,
				"abort do_send_xframe during "
				"device disconnect (%d)\n",
				rate_limit);
		ret = -ENODEV;
		goto failure;
	}
	/*
	 * If something really bad happend, do not overflow the USB stack
	 */
	if (atomic_read(&xusb->pending_writes) > MAX_PENDING_WRITES) {
		static int rate_limit;

		if ((rate_limit++ % 5000) == 0)
			XUSB_ERR(xusb,
				"USB device is totaly stuck. "
				"Dropping packets (#%d).\n",
				rate_limit);
		ret = -ENODEV;
		goto failure;
	}
	uframe = xframe->priv;
	BUG_ON(!uframe);
	BUG_ON(uframe->uframe_magic != UFRAME_MAGIC);
	uframe_recompute(uframe, XUSB_SEND);
	urb = &uframe->urb;
	BUG_ON(!urb);
	/* update urb length */
	urb->transfer_buffer_length = XFRAME_LEN(xframe);
	xframe->kt_submitted = ktime_get();
	ret = usb_submit_urb(urb, GFP_ATOMIC);
	if (ret < 0) {
		static int rate_limit;

		if ((rate_limit++ % 1000) == 0)
			XBUS_ERR(xbus, "%s: usb_submit_urb failed: %d\n",
				 __func__, ret);
		ret = -EBADF;
		goto failure;
	}
//      if (debug)
//              dump_xframe("USB_FRAME_SEND", xbus, xframe, debug);
	atomic_inc(&xusb->pending_writes);
	return 0;
failure:
	XUSB_COUNTER(xusb, TX_ERRORS)++;
	FREE_SEND_XFRAME(xbus, xframe);	/* return to pool */
	return ret;
}

/*
 * PCM wrapper
 */
static int xframe_send_pcm(xbus_t *xbus, xframe_t *xframe)
{
	xusb_t *xusb;

	BUG_ON(!xbus);
	BUG_ON(!xframe);
	xusb = xusb_of(xbus);
	BUG_ON(!xusb);
	if (xusb->drop_pcm) {
		static int rate_limit;

		if ((rate_limit++ % 1000) == 0)
			XUSB_ERR(xusb, "Sluggish USB: drop tx-pcm (%d)\n",
					rate_limit);
		/* Let trickle of TX-PCM, so Astribank will not reset */
		if (sluggish_pcm_keepalive &&
				((rate_limit % sluggish_pcm_keepalive) != 0)) {
			XUSB_COUNTER(xusb, TX_DROPS)++;
			goto err;
		}
	}
	return do_send_xframe(xbus, xframe);
err:
	FREE_SEND_XFRAME(xbus, xframe);	/* return to pool */
	return -EIO;
}

/*
 * commands wrapper
 */
static int xframe_send_cmd(xbus_t *xbus, xframe_t *xframe)
{
	BUG_ON(!xbus);
	BUG_ON(!xframe);
	//XBUS_INFO(xbus, "%s:\n", __func__);
	return do_send_xframe(xbus, xframe);
}

/*
 * get a urb from the receive_pool and submit it on the read endpoint.
 */
static bool xusb_listen(xusb_t *xusb)
{
	xbus_t *xbus = xbus_num(xusb->xbus_num);
	xframe_t *xframe;
	struct uframe *uframe;
	int ret = 0;

	BUG_ON(!xbus);
	xframe = ALLOC_RECV_XFRAME(xbus);
	if (!xframe) {
		XBUS_ERR(xbus, "Empty receive_pool\n");
		goto out;
	}
	uframe = xframe_to_uframe(xframe);
	uframe_recompute(uframe, XUSB_RECV);
	ret = usb_submit_urb(&uframe->urb, GFP_ATOMIC);
	if (ret < 0) {
		static int rate_limit;

		if ((rate_limit++ % 1000) == 0)
			XBUS_ERR(xbus, "%s: usb_submit_urb failed: %d\n",
				 __func__, ret);
		FREE_RECV_XFRAME(xbus, xframe);
		goto out;
	}
	atomic_inc(&xusb->pending_reads);
	ret = 1;
out:
	return ret;
}

/*------------------------- XPP USB Bus Handling -------------------*/

enum XUSB_MODELS {
	MODEL_FPGA_XPD
};

static const struct xusb_model_info {
	const char *desc;
	int iface_num;
	struct xusb_endpoint in;
	struct xusb_endpoint out;
} model_table[] = {
	[MODEL_FPGA_XPD] = {
		.iface_num = 0,
		.in = { .ep_addr = 0x86 },
		.out = { .ep_addr = 0x02 },
		.desc = "FPGA_XPD"
	},
};

/* table of devices that work with this driver */
static const struct usb_device_id xusb_table[] = {
/* FPGA_FXS */	{USB_DEVICE(0xE4E4, 0x1132),
		.driver_info = (kernel_ulong_t)&model_table[MODEL_FPGA_XPD]},
/* FPGA_1141 */	{USB_DEVICE(0xE4E4, 0x1142),
		.driver_info = (kernel_ulong_t)&model_table[MODEL_FPGA_XPD]},
/* FPGA_1151 */	{USB_DEVICE(0xE4E4, 0x1152),
		.driver_info = (kernel_ulong_t)&model_table[MODEL_FPGA_XPD]},
/* FPGA_1161 */	{USB_DEVICE(0xE4E4, 0x1162),
		.driver_info = (kernel_ulong_t)&model_table[MODEL_FPGA_XPD]},
/* Terminate */	{}
};

MODULE_DEVICE_TABLE(usb, xusb_table);

/*
 * USB specific object needed to register this driver
 * with the usb subsystem
 */
static struct usb_driver xusb_driver = {
	.name = "xpp_usb",
	.probe = xusb_probe,
	.disconnect = xusb_disconnect,
	.id_table = xusb_table,
};

/*
 * File operations needed when we register this driver.
 * This assumes that this driver NEEDS file operations,
 * of course, which means that the driver is expected
 * to have a node in the /dev directory. If the USB
 * device were for a network interface then the driver
 * would use "struct net_driver" instead, and a serial
 * device would use "struct tty_driver".
 */
static const struct file_operations xusb_fops = {
	/*
	 * The owner field is part of the module-locking
	 * mechanism. The idea is that the kernel knows
	 * which module to increment the use-counter of
	 * BEFORE it calls the device's open() function.
	 * This also means that the kernel can decrement
	 * the use-counter again before calling release()
	 * or should the open() function fail.
	 */
	.owner = THIS_MODULE,
};

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

/*
 * Check that an endpoint's wMaxPacketSize attribute is 512. This
 * indicates that it is a USB2's high speed end point.
 *
 * If it is 64, it means we have a USB1 controller. By default we do not
 * support it and just fail the probe of the device. However if the user
 * has set usb1=1, we continue and just put a notice.
 *
 * Returns true if all OK, false otherwise.
 */
static int check_usb1(struct usb_endpoint_descriptor *endpoint)
{
	const char *msg =
	    (usb_pipein(endpoint->bEndpointAddress)) ? "input" : "output";

	if (endpoint->wMaxPacketSize >= sizeof(xpacket_t))
		return 1;

	if (usb1) {
		NOTICE("USB1 endpoint detected: "
			"USB %s endpoint 0x%X support only wMaxPacketSize=%d\n",
			msg,
			endpoint->bEndpointAddress,
			endpoint->wMaxPacketSize);
		return 1;
	}
	NOTICE("USB1 endpoint detected: "
		"Device disabled. To enable: usb1=1, and read docs. "
		"(%s, endpoint %d, size %d)\n",
		msg, endpoint->bEndpointAddress, endpoint->wMaxPacketSize);
	return 0;
}

/*
 * set up the endpoint information
 * check out the endpoints
 * FIXME: Should be simplified (above 2.6.10) to use
 *        usb_dev->ep_in[0..16] and usb_dev->ep_out[0..16]
 */
static int set_endpoints(xusb_t *xusb, struct usb_host_interface *iface_desc,
			 struct xusb_model_info *model_info)
{
	struct usb_endpoint_descriptor *endpoint;
	struct xusb_endpoint *xusb_ep;
	int ep_addr;
	int i;

#define	BULK_ENDPOINT(ep) \
	(((ep)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == \
	USB_ENDPOINT_XFER_BULK)

	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;
		ep_addr = endpoint->bEndpointAddress;

		if (!BULK_ENDPOINT(endpoint)) {
			DBG(DEVICES,
			    "endpoint 0x%x is not bulk: mbAttributes=0x%X\n",
			    ep_addr, endpoint->bmAttributes);
			continue;
		}
		if (usb_pipein(ep_addr)) {	/* Input */
			if (ep_addr == model_info->in.ep_addr) {
				if (!check_usb1(endpoint))
					return 0;
				xusb_ep = &xusb->endpoints[XUSB_RECV];
				xusb_ep->ep_addr = ep_addr;
				xusb_ep->max_size = endpoint->wMaxPacketSize;
				xusb_ep->callback = xpp_receive_callback;
			}
		} else {			/* Output */
			if (ep_addr == model_info->out.ep_addr) {
				if (!check_usb1(endpoint))
					return 0;
				xusb_ep = &xusb->endpoints[XUSB_SEND];
				xusb_ep->ep_addr = ep_addr;
				xusb_ep->max_size = endpoint->wMaxPacketSize;
				xusb_ep->callback = xpp_send_callback;
			}
		}
	}
	if (!xusb->endpoints[XUSB_RECV].ep_addr
	    || !xusb->endpoints[XUSB_SEND].ep_addr) {
		XUSB_ERR(xusb, "Couldn't find bulk-in or bulk-out endpoints\n");
		return 0;
	}
	DBG(DEVICES, "in=0x%02X out=0x%02X\n",
	    xusb->endpoints[XUSB_RECV].ep_addr,
	    xusb->endpoints[XUSB_SEND].ep_addr);
	return 1;
}

/**
 *	xusb_probe
 *
 *	Called by the usb core when a new device is connected that it thinks
 *	this driver might be interested in.
 */
static int xusb_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 =
	    usb_altnum_to_altsetting(interface, 0);
	xusb_t *xusb = NULL;
	struct xusb_model_info *model_info =
	    (struct xusb_model_info *)id->driver_info;
#ifdef CONFIG_PROC_FS
	struct proc_dir_entry *procsummary = NULL;
#endif
	xbus_t *xbus = NULL;
	unsigned long flags;
	int retval = -ENOMEM;
	int i;

	DBG(DEVICES, "New XUSB device MODEL=%s\n", model_info->desc);
	if (iface_desc->desc.bInterfaceNumber != model_info->iface_num) {
		DBG(DEVICES, "Skip interface #%d != #%d\n",
		    iface_desc->desc.bInterfaceNumber, model_info->iface_num);
		return -ENODEV;
	}
	mutex_lock(&protect_xusb_devices);
	if ((retval = usb_reset_device(udev)) < 0) {
		ERR("usb_reset_device failed: %d\n", retval);
		goto probe_failed;
	}
	if (!model_info) {
		ERR("Missing endpoint setup for this device %d:%d\n",
		    udev->descriptor.idVendor, udev->descriptor.idProduct);
		retval = -ENODEV;
		goto probe_failed;
	}

	/* allocate memory for our device state and initialize it */
	xusb = KZALLOC(sizeof(xusb_t), GFP_KERNEL);
	if (xusb == NULL) {
		ERR("xpp_usb: Unable to allocate new xpp usb bus\n");
		retval = -ENOMEM;
		goto probe_failed;
	}
	sema_init(&xusb->sem, 1);
	atomic_set(&xusb->pending_writes, 0);
	atomic_set(&xusb->pending_reads, 0);
	atomic_set(&xusb->usb_sluggish_count, 0);
	xusb->udev = udev;
	xusb->interface = interface;
	xusb->model_info = model_info;

	if (!set_endpoints(xusb, iface_desc, model_info)) {
		retval = -ENODEV;
		goto probe_failed;
	}
	xusb->serial = udev->serial;
	xusb->manufacturer = udev->manufacturer;
	xusb->product = udev->product;
	xusb->interface_name = iface_desc->string;
	INFO("XUSB: %s -- %s -- %s\n", xusb->manufacturer, xusb->product,
	     xusb->interface_name);

	/* allow device read, write and ioctl */
	xusb->present = 1;

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

	xusb->minor = interface->minor;

	/* let the user know what node this device is now attached to */
	DBG(DEVICES, "USB XPP device now attached to minor %d\n", xusb->minor);
	xbus =
	    xbus_new(&xusb_ops,
		     min(xusb->endpoints[XUSB_SEND].max_size,
			 xusb->endpoints[XUSB_RECV].max_size), &udev->dev,
		     xusb);
	if (!xbus) {
		retval = -ENOMEM;
		goto probe_failed;
	}
	snprintf(xbus->transport.model_string,
		 ARRAY_SIZE(xbus->transport.model_string), "usb:%04x/%04x/%x",
		 udev->descriptor.idVendor, udev->descriptor.idProduct,
		 udev->descriptor.bcdDevice);
	spin_lock_irqsave(&xusb_lock, flags);
	for (i = 0; i < MAX_BUSES; i++) {
		if (xusb_array[i] == NULL)
			break;
	}
	spin_unlock_irqrestore(&xusb_lock, flags);
	if (i >= MAX_BUSES) {
		ERR("xpp_usb: Too many XPP USB buses\n");
		retval = -ENOMEM;
		goto probe_failed;
	}
	/* May trunacte... ignore */
	usb_make_path(udev, xusb->path, XBUS_DESCLEN);
	snprintf(xbus->connector, XBUS_DESCLEN, "%s", xusb->path);
	if (xusb->serial && xusb->serial[0])
		snprintf(xbus->label, LABEL_SIZE, "usb:%s", xusb->serial);
	xusb->index = i;
	xusb_array[i] = xusb;
	XUSB_DBG(DEVICES, xusb, "GOT XPP USB BUS: %s\n", xbus->connector);

#ifdef CONFIG_PROC_FS
	DBG(PROC,
	    "Creating proc entry " PROC_USBXPP_SUMMARY " in bus proc dir.\n");
	procsummary = proc_create_data(PROC_USBXPP_SUMMARY, 0444,
				   xbus->proc_xbus_dir, &xusb_read_proc_ops,
				   xusb);
	if (!procsummary) {
		XBUS_ERR(xbus, "Failed to create proc file '%s'\n",
			 PROC_USBXPP_SUMMARY);
		// FIXME: better error handling
		retval = -EIO;
		goto probe_failed;
	}
#endif
	bus_count++;
	xusb->xbus_num = xbus->num;
	/* prepare several pending frames for receive side */
	for (i = 0; i < 10; i++)
		xusb_listen(xusb);
	xbus_connect(xbus);
	mutex_unlock(&protect_xusb_devices);
	return retval;
probe_failed:
	ERR("Failed to initialize xpp usb bus: %d\n", retval);
	usb_set_intfdata(interface, NULL);
	if (xusb) {
		if (xusb->minor) {	/* passed registration phase */
			ERR("Calling usb_deregister_dev()\n");
			usb_deregister_dev(interface, &xusb_class);
		}
		ERR("Removing failed xusb\n");
		KZFREE(xusb);
	}
	if (xbus) {
#ifdef CONFIG_PROC_FS
		if (procsummary) {
			XBUS_DBG(PROC, xbus,
				 "Remove proc_entry: " PROC_USBXPP_SUMMARY
				 "\n");
			remove_proc_entry(PROC_USBXPP_SUMMARY,
					  xbus->proc_xbus_dir);
			procsummary = NULL;
		}
#endif
		ERR("Calling xbus_disconnect()\n");
		xbus_disconnect(xbus);	// Blocking until fully deactivated!
	}
	mutex_unlock(&protect_xusb_devices);
	return retval;
}

/**
 *	xusb_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.  It is also supposed to terminate any currently
 *	active urbs.  Unfortunately, usb_bulk_msg(), used in xusb_read(), does
 *	not provide any way to do this.  But at least we can cancel an active
 *	write.
 */
static void xusb_disconnect(struct usb_interface *interface)
{
	struct usb_host_interface *iface_desc =
	    usb_altnum_to_altsetting(interface, 0);
	xusb_t *xusb;
	xbus_t *xbus;
	int i;

	DBG(DEVICES, "CALLED on interface #%d\n",
	    iface_desc->desc.bInterfaceNumber);
	/* prevent races with open() */
	mutex_lock(&protect_xusb_devices);

	xusb = usb_get_intfdata(interface);
	usb_set_intfdata(interface, NULL);
	xusb->present = 0;
	xbus = xbus_num(xusb->xbus_num);

	/* find our xusb */
	for (i = 0; i < MAX_BUSES; i++) {
		if (xusb_array[i] == xusb)
			break;
	}
	BUG_ON(i >= MAX_BUSES);
	xusb_array[i] = NULL;

#ifdef CONFIG_PROC_FS
	if (xbus->proc_xbus_dir) {
		XBUS_DBG(PROC, xbus,
			 "Remove proc_entry: " PROC_USBXPP_SUMMARY "\n");
		remove_proc_entry(PROC_USBXPP_SUMMARY, xbus->proc_xbus_dir);
	}
#endif
	xbus_disconnect(xbus);	// Blocking until fully deactivated!

	down(&xusb->sem);

	/* give back our minor */
	usb_deregister_dev(interface, &xusb_class);

	up(&xusb->sem);
	DBG(DEVICES, "Semaphore released\n");
	XUSB_INFO(xusb, "now disconnected\n");
	KZFREE(xusb);

	mutex_unlock(&protect_xusb_devices);
}

static void xpp_send_callback(struct urb *urb)
{
	struct uframe *uframe = urb_to_uframe(urb);
	xframe_t *xframe = &uframe->xframe;
	xusb_t *xusb = uframe->xusb;
	xbus_t *xbus = xbus_num(xusb->xbus_num);
	ktime_t now;
	s64 usec;
	int writes = atomic_read(&xusb->pending_writes);
	int i;

	if (!xbus) {
		XUSB_ERR(xusb,
			"Sent URB does not belong to a valid xbus...\n");
		return;
	}
	//flip_parport_bit(6);
	atomic_dec(&xusb->pending_writes);
	now = ktime_get();
	xusb->last_tx = xframe->kt_submitted;
	usec = ktime_us_delta(now, xframe->kt_submitted);
	if (usec < 0)
		usec = 0; /* System clock jumped */
	if (usec > xusb->max_tx_delay)
		xusb->max_tx_delay = usec;
	i = div_s64(usec, USEC_BUCKET);
	if (i >= NUM_BUCKETS)
		i = NUM_BUCKETS - 1;
	xusb->usb_tx_delay[i]++;
	if (unlikely(usec > tx_sluggish)) {
		if (xusb->sluggish_debounce++ > drop_pcm_after) {
			static int rate_limit;

			/* skip first messages */
			if ((rate_limit++ % 1003) == 500)
				XUSB_NOTICE(xusb,
					"Sluggish USB. Dropping next PCM frame "
					"(pending_writes=%d)\n",
					writes);
			atomic_inc(&xusb->usb_sluggish_count);
			xusb->drop_pcm = 1;
			xusb->sluggish_debounce = 0;
		}
	} else {
		xusb->sluggish_debounce = 0;
		xusb->drop_pcm = 0;
	}
	/* sync/async unlink faults aren't errors */
	if (urb->status
	    && !(urb->status == -ENOENT || urb->status == -ECONNRESET)) {
		static int rate_limit;
		if ((rate_limit++ % 1000) < 10) {
			XUSB_ERR(xusb,
				"nonzero write bulk status received: "
				"%d (pending_writes=%d)\n",
				urb->status, writes);
			dump_xframe("usb-write-error", xbus, xframe, DBG_ANY);
		}
		XUSB_COUNTER(xusb, TX_ERRORS)++;
	} else
		XUSB_COUNTER(xusb, TX_FRAMES)++;
	FREE_SEND_XFRAME(xbus, xframe);
	if (!xusb->present)
		XUSB_ERR(xusb, "A urb from non-connected device?\n");
}

static void xpp_receive_callback(struct urb *urb)
{
	struct uframe *uframe = urb_to_uframe(urb);
	xframe_t *xframe = &uframe->xframe;
	xusb_t *xusb = uframe->xusb;
	xbus_t *xbus = xbus_num(xusb->xbus_num);
	size_t size;
	bool do_resubmit = 1;
	ktime_t now = ktime_get();

	atomic_dec(&xusb->pending_reads);
	if (!xbus) {
		XUSB_ERR(xusb,
			"Received URB does not belong to a valid xbus...\n");
		return;
	}
	if (!xusb->present) {
		do_resubmit = 0;
		goto err;
	}
	if (urb->status) {
		DBG(GENERAL, "nonzero read bulk status received: %d\n",
		    urb->status);
		XUSB_COUNTER(xusb, RX_ERRORS)++;
		goto err;
	}
	size = urb->actual_length;
	if (size == 0) {
		static int rate_limit;

		if ((rate_limit++ % 5003) == 0)
			XUSB_NOTICE(xusb, "Received a zero length URBs (%d)\n",
				    rate_limit);
		XUSB_COUNTER(xusb, RCV_ZERO_LEN)++;
		goto err;
	}
	atomic_set(&xframe->frame_len, size);
	xframe->kt_received = now;

//      if (debug)
//              dump_xframe("USB_FRAME_RECEIVE", xbus, xframe, debug);
	XUSB_COUNTER(xusb, RX_FRAMES)++;
	if (xusb->drop_pcm) {
		/* some protocol analysis */
		static int rate_limit;
		xpacket_t *pack = (xpacket_t *)(xframe->packets);
		bool is_pcm = XPACKET_IS_PCM(pack);

		if (is_pcm) {
			if ((rate_limit++ % 1000) == 0)
				XUSB_ERR(xusb,
					"Sluggish USB: drop rx-pcm (%d)\n",
					rate_limit);
			/* Let trickle of RX-PCM, so Astribank will not reset */
			if (sluggish_pcm_keepalive &&
					((rate_limit % sluggish_pcm_keepalive)
					 != 0)) {
				XUSB_COUNTER(xusb, RX_DROPS)++;
				goto err;
			}
		}
	}
	/* Send UP */
	xbus_receive_xframe(xbus, xframe);
end:
	if (do_resubmit)
		xusb_listen(xusb);
	return;
err:
	FREE_RECV_XFRAME(xbus, xframe);
	goto end;
}

/*------------------------- Initialization -------------------------*/

static void xpp_usb_cleanup(void)
{
	if (xusb_cache) {
		kmem_cache_destroy(xusb_cache);
		xusb_cache = NULL;
	}
}

static int __init xpp_usb_init(void)
{
	int ret;
	//xusb_t *xusb;

	xusb_cache =
	    kmem_cache_create("xusb_cache", sizeof(xframe_t) + XFRAME_DATASIZE,
			      0, 0, NULL);
	if (!xusb_cache) {
		ret = -ENOMEM;
		goto failure;
	}

	/* register this driver with the USB subsystem */
	ret = usb_register(&xusb_driver);
	if (ret) {
		ERR("usb_register failed. Error number %d\n", ret);
		goto failure;
	}
	return 0;
failure:
	xpp_usb_cleanup();
	return ret;
}

static void __exit xpp_usb_shutdown(void)
{
	DBG(GENERAL, "\n");
	/* deregister this driver with the USB subsystem */
	usb_deregister(&xusb_driver);
	xpp_usb_cleanup();
}

#ifdef CONFIG_PROC_FS

static int xusb_read_proc_show(struct seq_file *sfile, void *data)
{
	unsigned long flags;
	int i;
	//unsigned long stamp = jiffies;
	xusb_t *xusb = sfile->private;
	uint usb_tx_delay[NUM_BUCKETS];
	const int mark_limit = tx_sluggish / USEC_BUCKET;

	if (!xusb)
		return 0;

	// TODO: probably needs a per-xusb lock:
	spin_lock_irqsave(&xusb_lock, flags);
	seq_printf(sfile, "Device: %03d/%03d\n", xusb->udev->bus->busnum,
		    xusb->udev->devnum);
	seq_printf(sfile, "USB: manufacturer=%s\n", xusb->manufacturer);
	seq_printf(sfile, "USB: product=%s\n", xusb->product);
	seq_printf(sfile, "USB: serial=%s\n", xusb->serial);
	seq_printf(sfile, "Minor: %d\nModel Info: %s\n", xusb->minor,
		    xusb->model_info->desc);
	seq_printf(sfile,
		    "Endpoints:\n" "\tIn:  0x%02X  - Size: %d)\n"
		    "\tOut: 0x%02X  - Size: %d)\n",
		    xusb->endpoints[XUSB_RECV].ep_addr,
		    xusb->endpoints[XUSB_RECV].max_size,
		    xusb->endpoints[XUSB_SEND].ep_addr,
		    xusb->endpoints[XUSB_SEND].max_size);
	seq_printf(sfile, "\npending_writes=%d\n",
		    atomic_read(&xusb->pending_writes));
	seq_printf(sfile, "pending_reads=%d\n",
		    atomic_read(&xusb->pending_reads));
	seq_printf(sfile, "max_tx_delay=%d\n", xusb->max_tx_delay);
	xusb->max_tx_delay = 0;
#ifdef	DEBUG_PCM_TIMING
	seq_printf(sfile,
		    "\nstamp_last_pcm_read=%lld accumulate_diff=%lld\n",
		    stamp_last_pcm_read, accumulate_diff);
#endif
	memcpy(usb_tx_delay, xusb->usb_tx_delay, sizeof(usb_tx_delay));
	seq_printf(sfile, "usb_tx_delay[%dus - %dus]: ",
		USEC_BUCKET * BUCKET_START,
		USEC_BUCKET * NUM_BUCKETS);
	for (i = BUCKET_START; i < NUM_BUCKETS; i++) {
		seq_printf(sfile, "%6d ", usb_tx_delay[i]);
		if (i == mark_limit)
			seq_printf(sfile, "| ");
	}
	seq_printf(sfile, "\nSluggish events: %d\n",
		    atomic_read(&xusb->usb_sluggish_count));
	seq_printf(sfile, "\nCOUNTERS:\n");
	for (i = 0; i < XUSB_COUNTER_MAX; i++) {
		seq_printf(sfile, "\t%-15s = %d\n", xusb_counters[i].name,
			    xusb->counters[i]);
	}
#if 0
	seq_printf(sfile, "<-- len=%d\n", len);
#endif
	spin_unlock_irqrestore(&xusb_lock, flags);
	return 0;
}

static int xusb_read_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, xusb_read_proc_show, PDE_DATA(inode));
}

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
static const struct proc_ops xusb_read_proc_ops = {
	.proc_open	= xusb_read_proc_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= single_release,
};
#else
static const struct file_operations xusb_read_proc_ops = {
	.owner		= THIS_MODULE,
	.open		= xusb_read_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
#endif


#endif

MODULE_DESCRIPTION("XPP USB Transport Driver");
MODULE_AUTHOR("Oron Peled <oron@actcom.co.il>");
MODULE_LICENSE("GPL");

module_init(xpp_usb_init);
module_exit(xpp_usb_shutdown);