Subject: [PATCH 1 of 7] USB auserwald driver added
From: Greg KH <[email-masked]>
To: [email-masked]
Cc: [email-masked], [email-masked]

Hi,

Here's a patch against 2.5.2-pre9 that adds a USB driver for all of the
auerswald ISDN devices.  The patch was written by Wolfgang Mües.

thanks,

greg k-h

diff -Nru a/Documentation/Configure.help b/Documentation/Configure.help
--- a/Documentation/Configure.help	Sun Jan  6 12:18:36 2002
+++ b/Documentation/Configure.help	Sun Jan  6 12:18:36 2002
@@ -13514,6 +13514,16 @@
   The module will be called rio500.o. If you want to compile it as
   a module, say M here and read <file:Documentation/modules.txt>.
 
+USB Auerswald ISDN device support
+CONFIG_USB_AUERSWALD
+  Say Y here if you want to connect an Auerswald USB ISDN Device
+  to your computer's USB port.
+
+  This code is also available as a module ( = code which can be
+  inserted in and removed from the running kernel whenever you want).
+  The module will be called auerswald.o. If you want to compile it as
+  a module, say M here and read <file:Documentation/modules.txt>.
+
 D-Link DSB-R100 FM radio support
 CONFIG_USB_DSBR
   Say Y here if you want to connect this type of radio to your
diff -Nru a/Documentation/usb/auerswald.txt b/Documentation/usb/auerswald.txt
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/Documentation/usb/auerswald.txt	Sun Jan  6 12:18:37 2002
@@ -0,0 +1,30 @@
+		Auerswald USB kernel driver
+		===========================
+
+What is it? What can I do with it?
+==================================
+The auerswald USB kernel driver connects your linux 2.4.x
+system to the auerswald usb-enabled devices.
+
+There are two types of auerswald usb devices:
+a) small PBX systems (ISDN)
+b) COMfort system telephones (ISDN)
+
+The driver installation creates the devices
+/dev/usb/auer0..15. These devices carry a vendor-
+specific protocol. You may run all auerswald java
+software on it. The java software needs a native
+library "libAuerUsbJNINative.so" installed on
+your system. This library is available from
+auerswald and shipped as part of the java software.
+
+You may create the devices with:
+	mknod -m 666 /dev/usb/auer0 c 180 80
+	...
+	mknod -m 666 /dev/usb/auer15 c 180 95
+
+Future plans
+============
+- Connection to ISDN4LINUX (the hisax interface)
+
+The maintainer of this driver is [email-masked]
diff -Nru a/drivers/usb/auerswald.c b/drivers/usb/auerswald.c
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/drivers/usb/auerswald.c	Sun Jan  6 12:18:37 2002
@@ -0,0 +1,2156 @@
+/*****************************************************************************/
+/*
+ *      auerswald.c  --  Auerswald PBX/System Telephone usb driver.
+ *
+ *      Copyright (C) 2001  Wolfgang Mües ([email-masked])
+ *
+ *      Very much code of this driver is borrowed from dabusb.c (Deti Fliegl)
+ *      and from the USB Skeleton driver (Greg Kroah-Hartman). Thank you.
+ *
+ *      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.
+ */
+ /*****************************************************************************/
+
+/* Standard Linux module include files */
+#include <asm/uaccess.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/devfs_fs_kernel.h>
+#undef DEBUG   		/* include debug macros until it's done	*/
+#include <linux/usb.h>
+
+/*-------------------------------------------------------------------*/
+/* Debug support 						     */
+#ifdef DEBUG
+#define dump( adr, len) \
+do {			\
+	unsigned int u;	\
+	printk (KERN_DEBUG); \
+	for (u = 0; u < len; u++) \
+		printk (" %02X", adr[u] & 0xFF); \
+	printk ("\n"); \
+} while (0)
+#else
+#define dump( adr, len)
+#endif
+
+/*-------------------------------------------------------------------*/
+/* Version Information */
+#define DRIVER_VERSION "0.9.9"
+#define DRIVER_AUTHOR  "Wolfgang Mües <[email-masked]>"
+#define DRIVER_DESC    "Auerswald PBX/System Telephone usb driver"
+
+/*-------------------------------------------------------------------*/
+/* Private declarations for Auerswald USB driver                     */
+
+/* Auerswald Vendor ID */
+#define ID_AUERSWALD  	0x09BF
+
+#ifndef AUER_MINOR_BASE		/* allow external override */
+#define AUER_MINOR_BASE	80	/* auerswald driver minor number */
+#endif
+
+/* we can have up to this number of device plugged in at once */
+#define AUER_MAX_DEVICES 16
+
+/* prefix for the device descriptors in /dev/usb */
+#define AU_PREFIX	"auer"
+
+/* Number of read buffers for each device */
+#define AU_RBUFFERS     10
+
+/* Number of chain elements for each control chain */
+#define AUCH_ELEMENTS   20
+
+/* Number of retries in communication */
+#define AU_RETRIES	10
+
+/*-------------------------------------------------------------------*/
+/* vendor specific protocol                                          */
+/* Header Byte */
+#define AUH_INDIRMASK   0x80    /* mask for direct/indirect bit */
+#define AUH_DIRECT      0x00    /* data is for USB device */
+#define AUH_INDIRECT    0x80    /* USB device is relay */
+
+#define AUH_SPLITMASK   0x40    /* mask for split bit */
+#define AUH_UNSPLIT     0x00    /* data block is full-size */
+#define AUH_SPLIT       0x40    /* data block is part of a larger one,
+                                   split-byte follows */
+
+#define AUH_TYPEMASK    0x3F    /* mask for type of data transfer */
+#define AUH_TYPESIZE    0x40    /* different types */
+#define AUH_DCHANNEL    0x00    /* D channel data */
+#define AUH_B1CHANNEL   0x01    /* B1 channel transparent */
+#define AUH_B2CHANNEL   0x02    /* B2 channel transparent */
+/*                0x03..0x0F       reserved for driver internal use */
+#define AUH_COMMAND     0x10    /* Command channel */
+#define AUH_BPROT       0x11    /* Configuration block protocol */
+#define AUH_DPROTANA    0x12    /* D channel protocol analyzer */
+#define AUH_TAPI        0x13    /* telephone api data (ATD) */
+/*                0x14..0x3F       reserved for other protocols */
+#define AUH_UNASSIGNED  0xFF    /* if char device has no assigned service */
+#define AUH_FIRSTUSERCH 0x11    /* first channel which is available for driver users */
+
+#define AUH_SIZE	1 	/* Size of Header Byte */
+
+/* Split Byte. Only present if split bit in header byte set.*/
+#define AUS_STARTMASK   0x80    /* mask for first block of splitted frame */
+#define AUS_FIRST       0x80    /* first block */
+#define AUS_FOLLOW      0x00    /* following block */
+
+#define AUS_ENDMASK     0x40    /* mask for last block of splitted frame */
+#define AUS_END         0x40    /* last block */
+#define AUS_NOEND       0x00    /* not the last block */
+
+#define AUS_LENMASK     0x3F    /* mask for block length information */
+
+/* Request types */
+#define AUT_RREQ        (USB_DIR_IN  | USB_TYPE_VENDOR | USB_RECIP_OTHER)   /* Read Request */
+#define AUT_WREQ        (USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER)   /* Write Request */
+
+/* Vendor Requests */
+#define AUV_GETINFO     0x00    /* GetDeviceInfo */
+#define AUV_WBLOCK      0x01    /* Write Block */
+#define AUV_RBLOCK      0x02    /* Read Block */
+#define AUV_CHANNELCTL  0x03    /* Channel Control */
+#define AUV_DUMMY	0x04	/* Dummy Out for retry */
+
+/* Device Info Types */
+#define AUDI_NUMBCH     0x0000  /* Number of supported B channels */
+#define AUDI_OUTFSIZE   0x0001  /* Size of OUT B channel fifos */
+#define AUDI_MBCTRANS   0x0002  /* max. Blocklength of control transfer */
+
+/* Interrupt endpoint definitions */
+#define AU_IRQENDP      1       /* Endpoint number */
+#define AU_IRQCMDID     16      /* Command-block ID */
+#define AU_BLOCKRDY     0       /* Command: Block data ready on ctl endpoint */
+#define AU_IRQMINSIZE	5	/* Nr. of bytes decoded in this driver */
+
+/* Device String Descriptors */
+#define AUSI_VENDOR   	1	/* "Auerswald GmbH & Co. KG" */
+#define AUSI_DEVICE   	2	/* Name of the Device */
+#define AUSI_SERIALNR 	3	/* Serial Number */
+#define AUSI_MSN      	4	/* "MSN ..." (first) Multiple Subscriber Number */
+
+#define AUSI_DLEN	100	/* Max. Length of Device Description */
+
+#define AUV_RETRY	0x101	/* First Firmware version which can do control retries */
+
+/*-------------------------------------------------------------------*/
+/* External data structures / Interface                              */
+typedef struct
+{
+        char *buf;               /* return buffer for string contents */
+        unsigned int bsize;      /* size of return buffer */
+} audevinfo_t,*paudevinfo_t;
+
+/* IO controls */
+#define IOCTL_AU_SLEN	  _IOR( 'U', 0xF0, int)         /* return the max. string descriptor length */
+#define IOCTL_AU_DEVINFO  _IOWR('U', 0xF1, audevinfo_t) /* get name of a specific device */
+#define IOCTL_AU_SERVREQ  _IOW( 'U', 0xF2, int) 	/* request a service channel */
+#define IOCTL_AU_BUFLEN	  _IOR( 'U', 0xF3, int)         /* return the max. buffer length for the device */
+#define IOCTL_AU_RXAVAIL  _IOR( 'U', 0xF4, int)         /* return != 0 if Receive Data available */
+#define IOCTL_AU_CONNECT  _IOR( 'U', 0xF5, int)         /* return != 0 if connected to a service channel */
+#define IOCTL_AU_TXREADY  _IOR( 'U', 0xF6, int)         /* return != 0 if Transmitt channel ready to send */
+/*                              'U'  0xF7..0xFF reseved */
+
+/*-------------------------------------------------------------------*/
+/* Internal data structures                                          */
+
+/* ..................................................................*/
+/* urb chain element */
+struct  auerchain;                      /* forward for circular reference */
+typedef struct
+{
+        struct auerchain *chain;        /* pointer to the chain to which this element belongs */
+        urb_t * urbp;                   /* pointer to attached urb */
+        void *context;                  /* saved URB context */
+        usb_complete_t complete;        /* saved URB completion function */
+        struct list_head list;          /* to include element into a list */
+} auerchainelement_t,*pauerchainelement_t;
+
+/* urb chain */
+typedef struct auerchain
+{
+        pauerchainelement_t active;     /* element which is submitted to urb */
+	spinlock_t lock;                /* protection agains interrupts */
+        struct list_head waiting_list;  /* list of waiting elements */
+        struct list_head free_list;     /* list of available elements */
+} auerchain_t,*pauerchain_t;
+
+/* ...................................................................*/
+/* buffer element */
+struct  auerbufctl;                     /* forward */
+typedef struct
+{
+        char *bufp;                     /* reference to allocated data buffer */
+        unsigned int len;               /* number of characters in data buffer */
+	unsigned int retries;		/* for urb retries */
+        struct usb_ctrlrequest *dr;	/* for setup data in control messages */
+        urb_t * urbp;                   /* USB urb */
+        struct auerbufctl *list;        /* pointer to list */
+        struct list_head buff_list;     /* reference to next buffer in list */
+} auerbuf_t,*pauerbuf_t;
+
+/* buffer list control block */
+typedef struct auerbufctl
+{
+        spinlock_t lock;                /* protection in interrupt */
+        struct list_head free_buff_list;/* free buffers */
+        struct list_head rec_buff_list; /* buffers with receive data */
+} auerbufctl_t,*pauerbufctl_t;
+
+/* ...................................................................*/
+/* service context */
+struct  auerscon;                       /* forward */
+typedef void (*auer_dispatch_t)(struct auerscon*, pauerbuf_t);
+typedef void (*auer_disconn_t) (struct auerscon*);
+typedef struct auerscon
+{
+        unsigned int id;                /* protocol service id AUH_xxxx */
+        auer_dispatch_t dispatch;       /* dispatch read buffer */
+	auer_disconn_t disconnect;	/* disconnect from device, wake up all char readers */
+} auerscon_t,*pauerscon_t;
+
+/* ...................................................................*/
+/* USB device context */
+typedef struct
+{
+	struct semaphore 	mutex;         	    /* protection in user context */
+	char 			name[16];	    /* name of the /dev/usb entry */
+	unsigned int		dtindex;	    /* index in the device table */
+	devfs_handle_t 		devfs;	 	    /* devfs device node */
+	struct usb_device *	usbdev;      	    /* USB device handle */
+	int			open_count;	    /* count the number of open character channels */
+        char 			dev_desc[AUSI_DLEN];/* for storing a textual description */
+        unsigned int 		maxControlLength;   /* max. Length of control paket (without header) */
+        urb_t * 		inturbp;            /* interrupt urb */
+        char *			intbufp;            /* data buffer for interrupt urb */
+	unsigned int 		irqsize;	    /* size of interrupt endpoint 1 */
+        struct auerchain 	controlchain;  	    /* for chaining of control messages */
+	auerbufctl_t 		bufctl;             /* Buffer control for control transfers */
+        pauerscon_t 	     	services[AUH_TYPESIZE];/* context pointers for each service */
+	unsigned int		version;	    /* Version of the device */
+	wait_queue_head_t 	bufferwait;         /* wait for a control buffer */
+} auerswald_t,*pauerswald_t;
+
+/* the global usb devfs handle */
+extern devfs_handle_t usb_devfs_handle;
+
+/* array of pointers to our devices that are currently connected */
+static pauerswald_t dev_table[AUER_MAX_DEVICES];
+
+/* lock to protect the dev_table structure */
+static struct semaphore dev_table_mutex;
+
+/* ................................................................... */
+/* character device context */
+typedef struct
+{
+	struct semaphore mutex;         /* protection in user context */
+	pauerswald_t auerdev;           /* context pointer of assigned device */
+        auerbufctl_t bufctl;            /* controls the buffer chain */
+        auerscon_t scontext;            /* service context */
+	wait_queue_head_t readwait;     /* for synchronous reading */
+	struct semaphore readmutex;     /* protection against multiple reads */
+	pauerbuf_t readbuf;		/* buffer held for partial reading */
+	unsigned int readoffset;	/* current offset in readbuf */
+	unsigned int removed;		/* is != 0 if device is removed */
+} auerchar_t,*pauerchar_t;
+
+
+/*-------------------------------------------------------------------*/
+/* Forwards */
+static void auerswald_ctrlread_complete (urb_t * urb);
+static void auerswald_removeservice (pauerswald_t cp, pauerscon_t scp);
+
+
+/*-------------------------------------------------------------------*/
+/* USB chain helper functions                                        */
+/* --------------------------                                        */
+
+/* completion function for chained urbs */
+static void auerchain_complete (urb_t * urb)
+{
+	unsigned long flags;
+        int result;
+
+        /* get pointer to element and to chain */
+        pauerchainelement_t acep = (pauerchainelement_t) urb->context;
+        pauerchain_t         acp = acep->chain;
+
+        /* restore original entries in urb */
+        urb->context  = acep->context;
+        urb->complete = acep->complete;
+
+        dbg ("auerchain_complete called");
+
+        /* call original completion function
+           NOTE: this function may lead to more urbs submitted into the chain.
+                 (no chain lock at calling complete()!)
+                 acp->active != NULL is protecting us against recursion.*/
+        urb->complete (urb);
+
+        /* detach element from chain data structure */
+	spin_lock_irqsave (&acp->lock, flags);
+        if (acp->active != acep) /* paranoia debug check */
+	        dbg ("auerchain_complete: completion on non-active element called!");
+        else
+                acp->active = NULL;
+
+        /* add the used chain element to the list of free elements */
+	list_add_tail (&acep->list, &acp->free_list);
+        acep = NULL;
+
+        /* is there a new element waiting in the chain? */
+        if (!acp->active && !list_empty (&acp->waiting_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = acp->waiting_list.next;
+                list_del (tmp);
+                acep = list_entry (tmp, auerchainelement_t, list);
+                acp->active = acep;
+        }
+        spin_unlock_irqrestore (&acp->lock, flags);
+
+        /* submit the new urb */
+        if (acep) {
+                urb    = acep->urbp;
+                dbg ("auerchain_complete: submitting next urb from chain");
+		urb->status = 0;	/* needed! */
+		result = usb_submit_urb( urb);
+
+                /* check for submit errors */
+                if (result) {
+                        urb->status = result;
+                        dbg("auerchain_complete: usb_submit_urb with error code %d", result);
+                        /* and do error handling via *this* completion function (recursive) */
+                        auerchain_complete( urb);
+                }
+        } else {
+                /* simple return without submitting a new urb.
+                   The empty chain is detected with acp->active == NULL. */
+        };
+}
+
+
+/* submit function for chained urbs
+   this function may be called from completion context or from user space!
+   early = 1 -> submit in front of chain
+*/
+static int auerchain_submit_urb_list (pauerchain_t acp, urb_t * urb, int early)
+{
+        int result;
+        unsigned long flags;
+        pauerchainelement_t acep = NULL;
+
+        dbg ("auerchain_submit_urb called");
+
+        /* try to get a chain element */
+        spin_lock_irqsave (&acp->lock, flags);
+        if (!list_empty (&acp->free_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = acp->free_list.next;
+                list_del (tmp);
+                acep = list_entry (tmp, auerchainelement_t, list);
+        }
+        spin_unlock_irqrestore (&acp->lock, flags);
+
+        /* if no chain element available: return with error */
+        if (!acep) {
+                return -ENOMEM;
+        }
+
+        /* fill in the new chain element values */
+        acep->chain    = acp;
+        acep->context  = urb->context;
+        acep->complete = urb->complete;
+        acep->urbp     = urb;
+        INIT_LIST_HEAD (&acep->list);
+
+        /* modify urb */
+        urb->context   = acep;
+        urb->complete  = auerchain_complete;
+        urb->status    = -EINPROGRESS;    /* usb_submit_urb does this, too */
+
+        /* add element to chain - or start it immediately */
+        spin_lock_irqsave (&acp->lock, flags);
+        if (acp->active) {
+                /* there is traffic in the chain, simple add element to chain */
+		if (early) {
+			dbg ("adding new urb to head of chain");
+			list_add (&acep->list, &acp->waiting_list);
+		} else {
+			dbg ("adding new urb to end of chain");
+			list_add_tail (&acep->list, &acp->waiting_list);
+		}
+		acep = NULL;
+        } else {
+                /* the chain is empty. Prepare restart */
+                acp->active = acep;
+        }
+        /* Spin has to be removed before usb_submit_urb! */
+        spin_unlock_irqrestore (&acp->lock, flags);
+
+        /* Submit urb if immediate restart */
+        if (acep) {
+                dbg("submitting urb immediate");
+		urb->status = 0;	/* needed! */
+                result = usb_submit_urb( urb);
+                /* check for submit errors */
+                if (result) {
+                        urb->status = result;
+                        dbg("auerchain_submit_urb: usb_submit_urb with error code %d", result);
+                        /* and do error handling via completion function */
+                        auerchain_complete( urb);
+                }
+        }
+
+        return 0;
+}
+
+/* submit function for chained urbs
+   this function may be called from completion context or from user space!
+*/
+static int auerchain_submit_urb (pauerchain_t acp, urb_t * urb)
+{
+	return auerchain_submit_urb_list (acp, urb, 0);
+}
+
+/* cancel an urb which is submitted to the chain
+   the result is 0 if the urb is cancelled, or -EINPROGRESS if
+   USB_ASYNC_UNLINK is set and the function is successfully started.
+*/
+static int auerchain_unlink_urb (pauerchain_t acp, urb_t * urb)
+{
+	unsigned long flags;
+        urb_t * urbp;
+        pauerchainelement_t acep;
+        struct list_head *tmp;
+
+        dbg ("auerchain_unlink_urb called");
+
+        /* search the chain of waiting elements */
+        spin_lock_irqsave (&acp->lock, flags);
+        list_for_each (tmp, &acp->waiting_list) {
+                acep = list_entry (tmp, auerchainelement_t, list);
+                if (acep->urbp == urb) {
+                        list_del (tmp);
+                        urb->context = acep->context;
+                        urb->complete = acep->complete;
+                        list_add_tail (&acep->list, &acp->free_list);
+                        spin_unlock_irqrestore (&acp->lock, flags);
+                        dbg ("unlink waiting urb");
+                        urb->status = -ENOENT;
+                        urb->complete (urb);
+                        return 0;
+                }
+        }
+        /* not found. */
+        spin_unlock_irqrestore (&acp->lock, flags);
+
+        /* get the active urb */
+        acep = acp->active;
+        if (acep) {
+                urbp = acep->urbp;
+
+                /* check if we have to cancel the active urb */
+                if (urbp == urb) {
+                        /* note that there is a race condition between the check above
+                           and the unlink() call because of no lock. This race is harmless,
+                           because the usb module will detect the unlink() after completion.
+                           We can't use the acp->lock here because the completion function
+                           wants to grab it.
+			*/
+                        dbg ("unlink active urb");
+                        return usb_unlink_urb (urbp);
+                }
+        }
+
+        /* not found anyway
+           ... is some kind of success
+	*/
+        dbg ("urb to unlink not found in chain");
+        return 0;
+}
+
+/* cancel all urbs which are in the chain.
+   this function must not be called from interrupt or completion handler.
+*/
+static void auerchain_unlink_all (pauerchain_t acp)
+{
+	unsigned long flags;
+        urb_t * urbp;
+        pauerchainelement_t acep;
+
+        dbg ("auerchain_unlink_all called");
+
+        /* clear the chain of waiting elements */
+        spin_lock_irqsave (&acp->lock, flags);
+        while (!list_empty (&acp->waiting_list)) {
+                /* get the next entry */
+                struct list_head *tmp = acp->waiting_list.next;
+                list_del (tmp);
+                acep = list_entry (tmp, auerchainelement_t, list);
+                urbp = acep->urbp;
+                urbp->context = acep->context;
+                urbp->complete = acep->complete;
+                list_add_tail (&acep->list, &acp->free_list);
+                spin_unlock_irqrestore (&acp->lock, flags);
+                dbg ("unlink waiting urb");
+                urbp->status = -ENOENT;
+                urbp->complete (urbp);
+                spin_lock_irqsave (&acp->lock, flags);
+        }
+        spin_unlock_irqrestore (&acp->lock, flags);
+
+        /* clear the active urb */
+        acep = acp->active;
+        if (acep) {
+                urbp = acep->urbp;
+                urbp->transfer_flags &= ~USB_ASYNC_UNLINK;
+                dbg ("unlink active urb");
+                usb_unlink_urb (urbp);
+        }
+}
+
+
+/* free the chain.
+   this function must not be called from interrupt or completion handler.
+*/
+static void auerchain_free (pauerchain_t acp)
+{
+	unsigned long flags;
+        pauerchainelement_t acep;
+
+        dbg ("auerchain_free called");
+
+        /* first, cancel all pending urbs */
+        auerchain_unlink_all (acp);
+
+        /* free the elements */
+        spin_lock_irqsave (&acp->lock, flags);
+        while (!list_empty (&acp->free_list)) {
+                /* get the next entry */
+                struct list_head *tmp = acp->free_list.next;
+                list_del (tmp);
+                spin_unlock_irqrestore (&acp->lock, flags);
+		acep = list_entry (tmp, auerchainelement_t, list);
+                kfree (acep);
+	        spin_lock_irqsave (&acp->lock, flags);
+	}
+        spin_unlock_irqrestore (&acp->lock, flags);
+}
+
+
+/* Init the chain control structure */
+static void auerchain_init (pauerchain_t acp)
+{
+        /* init the chain data structure */
+        acp->active = NULL;
+	spin_lock_init (&acp->lock);
+        INIT_LIST_HEAD (&acp->waiting_list);
+        INIT_LIST_HEAD (&acp->free_list);
+}
+
+/* setup a chain.
+   It is assumed that there is no concurrency while setting up the chain
+   requirement: auerchain_init()
+*/
+static int auerchain_setup (pauerchain_t acp, unsigned int numElements)
+{
+        pauerchainelement_t acep;
+
+        dbg ("auerchain_setup called with %d elements", numElements);
+
+        /* fill the list of free elements */
+        for (;numElements; numElements--) {
+                acep = (pauerchainelement_t) kmalloc (sizeof (auerchainelement_t), GFP_KERNEL);
+                if (!acep) goto ac_fail;
+		memset (acep, 0, sizeof (auerchainelement_t));
+                INIT_LIST_HEAD (&acep->list);
+                list_add_tail (&acep->list, &acp->free_list);
+        }
+        return 0;
+
+ac_fail:/* free the elements */
+        while (!list_empty (&acp->free_list)) {
+                /* get the next entry */
+                struct list_head *tmp = acp->free_list.next;
+                list_del (tmp);
+                acep = list_entry (tmp, auerchainelement_t, list);
+                kfree (acep);
+        }
+        return -ENOMEM;
+}
+
+
+/* completion handler for synchronous chained URBs */
+static void auerchain_blocking_completion (urb_t *urb)
+{
+	wait_queue_head_t *wakeup = (wait_queue_head_t *)urb->context;
+	wake_up (wakeup);
+}
+
+
+/* Starts chained urb and waits for completion or timeout */
+static int auerchain_start_wait_urb (pauerchain_t acp, urb_t *urb, int timeout, int* actual_length)
+{
+	DECLARE_WAITQUEUE (wait, current);
+	DECLARE_WAIT_QUEUE_HEAD (wqh);
+	int status;
+
+	dbg ("auerchain_start_wait_urb called");
+	init_waitqueue_head (&wqh);
+	current->state = TASK_INTERRUPTIBLE;
+	add_wait_queue (&wqh, &wait);
+	urb->context = &wqh;
+	status = auerchain_submit_urb ( acp, urb);
+	if (status) {
+		/* something went wrong */
+		current->state = TASK_RUNNING;
+		remove_wait_queue (&wqh, &wait);
+		return status;
+	}
+
+	if (urb->status == -EINPROGRESS) {
+		while (timeout && urb->status == -EINPROGRESS)
+			status = timeout = schedule_timeout (timeout);
+	} else
+		status = 1;
+
+	current->state = TASK_RUNNING;
+	remove_wait_queue (&wqh, &wait);
+
+	if (!status) {
+		/* timeout */
+		dbg ("auerchain_start_wait_urb: timeout");
+		auerchain_unlink_urb (acp, urb);  /* remove urb safely */
+		status = -ETIMEDOUT;
+	} else
+		status = urb->status;
+
+	if (actual_length)
+		*actual_length = urb->actual_length;
+
+  	return status;
+}
+
+
+/* auerchain_control_msg - Builds a control urb, sends it off and waits for completion
+   acp: pointer to the auerchain
+   dev: pointer to the usb device to send the message to
+   pipe: endpoint "pipe" to send the message to
+   request: USB message request value
+   requesttype: USB message request type value
+   value: USB message value
+   index: USB message index value
+   data: pointer to the data to send
+   size: length in bytes of the data to send
+   timeout: time to wait for the message to complete before timing out (if 0 the wait is forever)
+
+   This function sends a simple control message to a specified endpoint
+   and waits for the message to complete, or timeout.
+
+   If successful, it returns the transfered length, othwise a negative error number.
+
+   Don't use this function from within an interrupt context, like a
+   bottom half handler.  If you need a asyncronous message, or need to send
+   a message from within interrupt context, use auerchain_submit_urb()
+*/
+static int auerchain_control_msg (pauerchain_t acp, struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
+			          __u16 value, __u16 index, void *data, __u16 size, int timeout)
+{
+	int ret;
+	struct usb_ctrlrequest *dr;
+	urb_t *urb;
+        int length;
+
+        dbg ("auerchain_control_msg");
+        dr = kmalloc (sizeof (struct usb_ctrlrequest), GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
+	urb = usb_alloc_urb (0);
+	if (!urb) {
+        	kfree (dr);
+		return -ENOMEM;
+        }
+
+	dr->bRequestType = requesttype;
+	dr->bRequest = request;
+	dr->wValue  = cpu_to_le16 (value);
+	dr->wIndex  = cpu_to_le16 (index);
+	dr->wlength = cpu_to_le16 (size);
+
+	FILL_CONTROL_URB (urb, dev, pipe, (unsigned char*)dr, data, size,    /* build urb */
+		          (usb_complete_t)auerchain_blocking_completion,0);
+	ret = auerchain_start_wait_urb (acp, urb, timeout, &length);
+
+	usb_free_urb (urb);
+	kfree (dr);
+
+        if (ret < 0)
+		return ret;
+	else
+		return length;
+}
+
+
+/*-------------------------------------------------------------------*/
+/* Buffer List helper functions                                      */
+
+/* free a single auerbuf */
+static void auerbuf_free (pauerbuf_t bp)
+{
+	if (bp->bufp) {
+		kfree (bp->bufp);
+	}
+	if (bp->dr) {
+		kfree (bp->dr);
+	}
+	if (bp->urbp) {
+		usb_free_urb (bp->urbp);
+	}
+	kfree (bp);
+}
+
+/* free the buffers from an auerbuf list */
+static void auerbuf_free_list (struct list_head *q)
+{
+        struct list_head *tmp;
+	struct list_head *p;
+	pauerbuf_t bp;
+
+	dbg ("auerbuf_free_list");
+	for (p = q->next; p != q;) {
+		bp = list_entry (p, auerbuf_t, buff_list);
+		tmp = p->next;
+		list_del (p);
+		p = tmp;
+		auerbuf_free (bp);
+	}
+}
+
+/* init the members of a list control block */
+static void auerbuf_init (pauerbufctl_t bcp)
+{
+	dbg ("auerbuf_init");
+	spin_lock_init (&bcp->lock);
+        INIT_LIST_HEAD (&bcp->free_buff_list);
+        INIT_LIST_HEAD (&bcp->rec_buff_list);
+}
+
+/* free all buffers from an auerbuf chain */
+static void auerbuf_free_buffers (pauerbufctl_t bcp)
+{
+	unsigned long flags;
+	dbg ("auerbuf_free_buffers");
+
+        spin_lock_irqsave (&bcp->lock, flags);
+
+	auerbuf_free_list (&bcp->free_buff_list);
+	auerbuf_free_list (&bcp->rec_buff_list);
+
+        spin_unlock_irqrestore (&bcp->lock, flags);
+}
+
+/* setup a list of buffers */
+/* requirement: auerbuf_init() */
+static int auerbuf_setup (pauerbufctl_t bcp, unsigned int numElements, unsigned int bufsize)
+{
+        pauerbuf_t bep;
+
+        dbg ("auerbuf_setup called with %d elements of %d bytes", numElements, bufsize);
+
+        /* fill the list of free elements */
+        for (;numElements; numElements--) {
+                bep = (pauerbuf_t) kmalloc (sizeof (auerbuf_t), GFP_KERNEL);
+                if (!bep) goto bl_fail;
+	        memset (bep, 0, sizeof (auerbuf_t));
+                bep->list = bcp;
+                INIT_LIST_HEAD (&bep->buff_list);
+                bep->bufp = (char *) kmalloc (bufsize, GFP_KERNEL);
+                if (!bep->bufp) goto bl_fail;
+                bep->dr = (struct usb_ctrlrequest *) kmalloc (sizeof (struct usb_ctrlrequest), GFP_KERNEL);
+                if (!bep->dr) goto bl_fail;
+                bep->urbp = usb_alloc_urb (0);
+                if (!bep->urbp) goto bl_fail;
+                list_add_tail (&bep->buff_list, &bcp->free_buff_list);
+        }
+        return 0;
+
+bl_fail:/* not enought memory. Free allocated elements */
+        dbg ("auerbuf_setup: no more memory");
+        auerbuf_free_buffers (bcp);
+        return -ENOMEM;
+}
+
+/* insert a used buffer into the free list */
+static void auerbuf_releasebuf( pauerbuf_t bp)
+{
+        unsigned long flags;
+        pauerbufctl_t bcp = bp->list;
+	bp->retries = 0;
+
+        dbg ("auerbuf_releasebuf called");
+        spin_lock_irqsave (&bcp->lock, flags);
+	list_add_tail (&bp->buff_list, &bcp->free_buff_list);
+        spin_unlock_irqrestore (&bcp->lock, flags);
+}
+
+
+/*-------------------------------------------------------------------*/
+/* Completion handlers */
+
+/* Values of urb->status or results of usb_submit_urb():
+0		Initial, OK
+-EINPROGRESS	during submission until end
+-ENOENT		if urb is unlinked
+-ETIMEDOUT	Transfer timed out, NAK
+-ENOMEM		Memory Overflow
+-ENODEV		Specified USB-device or bus doesn't exist
+-ENXIO		URB already queued
+-EINVAL		a) Invalid transfer type specified (or not supported)
+		b) Invalid interrupt interval (0n256)
+-EAGAIN		a) Specified ISO start frame too early
+		b) (using ISO-ASAP) Too much scheduled for the future wait some time and try again.
+-EFBIG		Too much ISO frames requested (currently uhci900)
+-EPIPE		Specified pipe-handle/Endpoint is already stalled
+-EMSGSIZE	Endpoint message size is zero, do interface/alternate setting
+-EPROTO		a) Bitstuff error
+		b) Unknown USB error
+-EILSEQ		CRC mismatch
+-ENOSR		Buffer error
+-EREMOTEIO	Short packet detected
+-EXDEV		ISO transfer only partially completed look at individual frame status for details
+-EINVAL		ISO madness, if this happens: Log off and go home
+-EOVERFLOW	babble
+*/
+
+/* check if a status code allows a retry */
+static int auerswald_status_retry (int status)
+{
+	switch (status) {
+	case 0:
+	case -ETIMEDOUT:
+	case -EOVERFLOW:
+	case -EAGAIN:
+	case -EPIPE:
+	case -EPROTO:
+	case -EILSEQ:
+	case -ENOSR:
+	case -EREMOTEIO:
+		return 1; /* do a retry */
+	}
+	return 0;	/* no retry possible */
+}
+
+/* Completion of asynchronous write block */
+static void auerchar_ctrlwrite_complete (urb_t * urb)
+{
+	pauerbuf_t bp = (pauerbuf_t) urb->context;
+	pauerswald_t cp = ((pauerswald_t)((char *)(bp->list)-(unsigned long)(&((pauerswald_t)0)->bufctl)));
+	dbg ("auerchar_ctrlwrite_complete called");
+
+	/* reuse the buffer */
+	auerbuf_releasebuf (bp);
+	/* Wake up all processes waiting for a buffer */
+	wake_up (&cp->bufferwait);
+}
+
+/* Completion handler for dummy retry packet */
+static void auerswald_ctrlread_wretcomplete (urb_t * urb)
+{
+        pauerbuf_t bp = (pauerbuf_t) urb->context;
+        pauerswald_t cp;
+	int ret;
+        dbg ("auerswald_ctrlread_wretcomplete called");
+        dbg ("complete with status: %d", urb->status);
+	cp = ((pauerswald_t)((char *)(bp->list)-(unsigned long)(&((pauerswald_t)0)->bufctl)));
+
+	/* check if it is possible to advance */
+	if (!auerswald_status_retry (urb->status) || !cp->usbdev) {
+		/* reuse the buffer */
+		err ("control dummy: transmission error %d, can not retry", urb->status);
+		auerbuf_releasebuf (bp);
+		/* Wake up all processes waiting for a buffer */
+		wake_up (&cp->bufferwait);
+		return;
+	}
+
+	/* fill the control message */
+	bp->dr->requesttype = AUT_RREQ;
+	bp->dr->request     = AUV_RBLOCK;
+	bp->dr->length      = bp->dr->value;	/* temporary stored */
+	bp->dr->value       = cpu_to_le16 (1);	/* Retry Flag */
+	/* bp->dr->index    = channel id;          remains */
+	FILL_CONTROL_URB (bp->urbp, cp->usbdev, usb_rcvctrlpipe (cp->usbdev, 0),
+                          (unsigned char*)bp->dr, bp->bufp, le16_to_cpu (bp->dr->length),
+		          (usb_complete_t)auerswald_ctrlread_complete,bp);
+
+	/* submit the control msg as next paket */
+	ret = auerchain_submit_urb_list (&cp->controlchain, bp->urbp, 1);
+        if (ret) {
+        	dbg ("auerswald_ctrlread_complete: nonzero result of auerchain_submit_urb_list %d", ret);
+        	bp->urbp->status = ret;
+        	auerswald_ctrlread_complete (bp->urbp);
+    	}
+}
+
+/* completion handler for receiving of control messages */
+static void auerswald_ctrlread_complete (urb_t * urb)
+{
+        unsigned int  serviceid;
+        pauerswald_t  cp;
+        pauerscon_t   scp;
+        pauerbuf_t    bp  = (pauerbuf_t) urb->context;
+	int ret;
+        dbg ("auerswald_ctrlread_complete called");
+
+	cp = ((pauerswald_t)((char *)(bp->list)-(unsigned long)(&((pauerswald_t)0)->bufctl)));
+
+	/* check if there is valid data in this urb */
+        if (urb->status) {
+		dbg ("complete with non-zero status: %d", urb->status);
+		/* should we do a retry? */
+		if (!auerswald_status_retry (urb->status)
+		 || !cp->usbdev
+		 || (cp->version < AUV_RETRY)
+                 || (bp->retries >= AU_RETRIES)) {
+			/* reuse the buffer */
+			err ("control read: transmission error %d, can not retry", urb->status);
+			auerbuf_releasebuf (bp);
+			return;
+		}
+		bp->retries++;
+		dbg ("Retry count = %d", bp->retries);
+		/* send a long dummy control-write-message to allow device firmware to react */
+		bp->dr->requesttype = AUT_WREQ;
+		bp->dr->request     = AUV_DUMMY;
+		bp->dr->value       = bp->dr->length; /* temporary storage */
+		// bp->dr->index    channel ID remains
+		bp->dr->length      = cpu_to_le16 (32); /* >= 8 bytes */
+		FILL_CONTROL_URB (bp->urbp, cp->usbdev, usb_sndctrlpipe (cp->usbdev, 0),
+  			(unsigned char*)bp->dr, bp->bufp, 32,
+	   		(usb_complete_t)auerswald_ctrlread_wretcomplete,bp);
+
+		/* submit the control msg as next paket */
+       		ret = auerchain_submit_urb_list (&cp->controlchain, bp->urbp, 1);
+       		if (ret) {
+               		dbg ("auerswald_ctrlread_complete: nonzero result of auerchain_submit_urb_list %d", ret);
+               		bp->urbp->status = ret;
+               		auerswald_ctrlread_wretcomplete (bp->urbp);
+		}
+                return;
+        }
+
+        /* get the actual bytecount (incl. headerbyte) */
+        bp->len = urb->actual_length;
+        serviceid = bp->bufp[0] & AUH_TYPEMASK;
+        dbg ("Paket with serviceid %d and %d bytes received", serviceid, bp->len);
+
+        /* dispatch the paket */
+        scp = cp->services[serviceid];
+        if (scp) {
+                /* look, Ma, a listener! */
+                scp->dispatch (scp, bp);
+        }
+
+        /* release the paket */
+        auerbuf_releasebuf (bp);
+	/* Wake up all processes waiting for a buffer */
+	wake_up (&cp->bufferwait);
+}
+
+/*-------------------------------------------------------------------*/
+/* Handling of Interrupt Endpoint                                    */
+/* This interrupt Endpoint is used to inform the host about waiting
+   messages from the USB device.
+*/
+/* int completion handler. */
+static void auerswald_int_complete (urb_t * urb)
+{
+        unsigned long flags;
+        unsigned  int channelid;
+        unsigned  int bytecount;
+        int ret;
+        pauerbuf_t   bp = NULL;
+        pauerswald_t cp = (pauerswald_t) urb->context;
+
+        dbg ("auerswald_int_complete called");
+
+        /* do not respond to an error condition */
+        if (urb->status != 0) {
+                dbg ("nonzero URB status = %d", urb->status);
+                return;
+        }
+
+        /* check if all needed data was received */
+	if (urb->actual_length < AU_IRQMINSIZE) {
+                dbg ("invalid data length received: %d bytes", urb->actual_length);
+                return;
+        }
+
+        /* check the command code */
+        if (cp->intbufp[0] != AU_IRQCMDID) {
+                dbg ("invalid command received: %d", cp->intbufp[0]);
+                return;
+        }
+
+        /* check the command type */
+        if (cp->intbufp[1] != AU_BLOCKRDY) {
+                dbg ("invalid command type received: %d", cp->intbufp[1]);
+                return;
+        }
+
+        /* now extract the information */
+        channelid = cp->intbufp[2];
+        bytecount = le16_to_cpup (&cp->intbufp[3]);
+
+        /* check the channel id */
+        if (channelid >= AUH_TYPESIZE) {
+                dbg ("invalid channel id received: %d", channelid);
+                return;
+        }
+
+        /* check the byte count */
+        if (bytecount > (cp->maxControlLength+AUH_SIZE)) {
+                dbg ("invalid byte count received: %d", bytecount);
+                return;
+        }
+        dbg ("Service Channel = %d", channelid);
+        dbg ("Byte Count = %d", bytecount);
+
+        /* get a buffer for the next data paket */
+        spin_lock_irqsave (&cp->bufctl.lock, flags);
+        if (!list_empty (&cp->bufctl.free_buff_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = cp->bufctl.free_buff_list.next;
+                list_del (tmp);
+                bp = list_entry (tmp, auerbuf_t, buff_list);
+        }
+        spin_unlock_irqrestore (&cp->bufctl.lock, flags);
+
+        /* if no buffer available: skip it */
+        if (!bp) {
+                dbg ("auerswald_int_complete: no data buffer available");
+                /* can we do something more?
+		   This is a big problem: if this int packet is ignored, the
+		   device will wait forever and not signal any more data.
+		   The only real solution is: having enought buffers!
+		   Or perhaps temporary disabling the int endpoint?
+		*/
+		return;
+        }
+
+	/* fill the control message */
+        bp->dr->requesttype = AUT_RREQ;
+	bp->dr->request     = AUV_RBLOCK;
+	bp->dr->value       = cpu_to_le16 (0);
+	bp->dr->index       = cpu_to_le16 (channelid | AUH_DIRECT | AUH_UNSPLIT);
+	bp->dr->length      = cpu_to_le16 (bytecount);
+	FILL_CONTROL_URB (bp->urbp, cp->usbdev, usb_rcvctrlpipe (cp->usbdev, 0),
+                          (unsigned char*)bp->dr, bp->bufp, bytecount,
+		          (usb_complete_t)auerswald_ctrlread_complete,bp);
+
+        /* submit the control msg */
+        ret = auerchain_submit_urb (&cp->controlchain, bp->urbp);
+        if (ret) {
+                dbg ("auerswald_int_complete: nonzero result of auerchain_submit_urb %d", ret);
+                bp->urbp->status = ret;
+                auerswald_ctrlread_complete( bp->urbp);
+		/* here applies the same problem as above: device locking! */
+        }
+}
+
+/* int memory deallocation
+   NOTE: no mutex please!
+*/
+static void auerswald_int_free (pauerswald_t cp)
+{
+        if (cp->inturbp) {
+                usb_free_urb (cp->inturbp);
+                cp->inturbp = NULL;
+        }
+        if (cp->intbufp) {
+                kfree (cp->intbufp);
+                cp->intbufp = NULL;
+        }
+}
+
+/* This function is called to activate the interrupt
+   endpoint. This function returns 0 if successfull or an error code.
+   NOTE: no mutex please!
+*/
+static int auerswald_int_open (pauerswald_t cp)
+{
+        int ret;
+	struct usb_endpoint_descriptor *ep;
+	int irqsize;
+	dbg ("auerswald_int_open");
+
+	ep = usb_epnum_to_ep_desc (cp->usbdev, USB_DIR_IN | AU_IRQENDP);
+	if (!ep) {
+		ret = -EFAULT;
+  		goto intoend;
+    	}
+	irqsize = ep->wMaxPacketSize;
+	cp->irqsize = irqsize;
+
+	/* allocate the urb and data buffer */
+        if (!cp->inturbp) {
+                cp->inturbp = usb_alloc_urb (0);
+                if (!cp->inturbp) {
+                        ret = -ENOMEM;
+                        goto intoend;
+                }
+        }
+        if (!cp->intbufp) {
+                cp->intbufp = (char *) kmalloc (irqsize, GFP_KERNEL);
+                if (!cp->intbufp) {
+                        ret = -ENOMEM;
+                        goto intoend;
+                }
+        }
+        /* setup urb */
+        FILL_INT_URB (cp->inturbp, cp->usbdev, usb_rcvintpipe (cp->usbdev,AU_IRQENDP), cp->intbufp, irqsize, auerswald_int_complete, cp, ep->bInterval);
+        /* start the urb */
+	cp->inturbp->status = 0;	/* needed! */
+	ret = usb_submit_urb (cp->inturbp);
+
+intoend:
+        if (ret < 0) {
+                /* activation of interrupt endpoint has failed. Now clean up. */
+                dbg ("auerswald_int_open: activation of int endpoint failed");
+
+                /* deallocate memory */
+                auerswald_int_free (cp);
+        }
+        return ret;
+}
+
+/* This function is called to deactivate the interrupt
+   endpoint. This function returns 0 if successfull or an error code.
+   NOTE: no mutex please!
+*/
+static int auerswald_int_release (pauerswald_t cp)
+{
+        int ret = 0;
+        dbg ("auerswald_int_release");
+
+        /* stop the int endpoint */
+        if (cp->inturbp) {
+                ret = usb_unlink_urb (cp->inturbp);
+                if (ret)
+	                dbg ("nonzero int unlink result received: %d", ret);
+        }
+
+        /* deallocate memory */
+        auerswald_int_free (cp);
+
+        return ret;
+}
+
+/* --------------------------------------------------------------------- */
+/* Helper functions                                                      */
+
+/* wake up waiting readers */
+static void auerchar_disconnect (pauerscon_t scp)
+{
+        pauerchar_t ccp = ((pauerchar_t)((char *)(scp)-(unsigned long)(&((pauerchar_t)0)->scontext)));
+	dbg ("auerchar_disconnect called");
+	ccp->removed = 1;
+	wake_up (&ccp->readwait);
+}
+
+
+/* dispatch a read paket to a waiting character device */
+static void auerchar_ctrlread_dispatch (pauerscon_t scp, pauerbuf_t bp)
+{
+	unsigned long flags;
+        pauerchar_t ccp;
+        pauerbuf_t newbp = NULL;
+        char * charp;
+        dbg ("auerchar_ctrlread_dispatch called");
+        ccp = ((pauerchar_t)((char *)(scp)-(unsigned long)(&((pauerchar_t)0)->scontext)));
+
+        /* get a read buffer from character device context */
+        spin_lock_irqsave (&ccp->bufctl.lock, flags);
+        if (!list_empty (&ccp->bufctl.free_buff_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = ccp->bufctl.free_buff_list.next;
+                list_del (tmp);
+                newbp = list_entry (tmp, auerbuf_t, buff_list);
+        }
+        spin_unlock_irqrestore (&ccp->bufctl.lock, flags);
+
+        if (!newbp) {
+                dbg ("No read buffer available, discard paket!");
+                return;     /* no buffer, no dispatch */
+        }
+
+        /* copy information to new buffer element
+           (all buffers have the same length) */
+        charp = newbp->bufp;
+        newbp->bufp = bp->bufp;
+        bp->bufp = charp;
+        newbp->len = bp->len;
+
+        /* insert new buffer in read list */
+        spin_lock_irqsave (&ccp->bufctl.lock, flags);
+	list_add_tail (&newbp->buff_list, &ccp->bufctl.rec_buff_list);
+        spin_unlock_irqrestore (&ccp->bufctl.lock, flags);
+        dbg ("read buffer appended to rec_list");
+
+        /* wake up pending synchronous reads */
+	wake_up (&ccp->readwait);
+}
+
+
+/* Delete an auerswald driver context */
+static void auerswald_delete( pauerswald_t cp)
+{
+	dbg( "auerswald_delete");
+	if (cp == NULL) return;
+
+	/* Wake up all processes waiting for a buffer */
+	wake_up (&cp->bufferwait);
+
+	/* Cleaning up */
+	auerswald_int_release (cp);
+	auerchain_free (&cp->controlchain);
+	auerbuf_free_buffers (&cp->bufctl);
+
+	/* release the memory */
+	kfree( cp);
+}
+
+
+/* Delete an auerswald character context */
+static void auerchar_delete( pauerchar_t ccp)
+{
+	dbg ("auerchar_delete");
+	if (ccp == NULL) return;
+
+        /* wake up pending synchronous reads */
+	ccp->removed = 1;
+	wake_up (&ccp->readwait);
+
+	/* remove the read buffer */
+	if (ccp->readbuf) {
+		auerbuf_releasebuf (ccp->readbuf);
+		ccp->readbuf = NULL;
+	}
+
+	/* remove the character buffers */
+	auerbuf_free_buffers (&ccp->bufctl);
+
+	/* release the memory */
+	kfree( ccp);
+}
+
+
+/* add a new service to the device
+   scp->id must be set!
+   return: 0 if OK, else error code
+*/
+static int auerswald_addservice (pauerswald_t cp, pauerscon_t scp)
+{
+	int ret;
+
+	/* is the device available? */
+	if (!cp->usbdev) {
+		dbg ("usbdev == NULL");
+		return -EIO;	/*no: can not add a service, sorry*/
+	}
+
+	/* is the service available? */
+	if (cp->services[scp->id]) {
+		dbg ("service is busy");
+                return -EBUSY;
+	}
+
+	/* device is available, service is free */
+	cp->services[scp->id] = scp;
+
+	/* register service in device */
+	ret = auerchain_control_msg(
+		&cp->controlchain,                      /* pointer to control chain */
+		cp->usbdev,                             /* pointer to device */
+		usb_sndctrlpipe (cp->usbdev, 0),        /* pipe to control endpoint */
+		AUV_CHANNELCTL,                         /* USB message request value */
+		AUT_WREQ,                               /* USB message request type value */
+		0x01,              /* open                 USB message value */
+		scp->id,            		        /* USB message index value */
+		NULL,                                   /* pointer to the data to send */
+		0,                                      /* length in bytes of the data to send */
+		HZ * 2);                                /* time to wait for the message to complete before timing out */
+	if (ret < 0) {
+		dbg ("auerswald_addservice: auerchain_control_msg returned error code %d", ret);
+		/* undo above actions */
+		cp->services[scp->id] = NULL;
+		return ret;
+	}
+
+	dbg ("auerswald_addservice: channel open OK");
+	return 0;
+}
+
+
+/* remove a service from the the device
+   scp->id must be set! */
+static void auerswald_removeservice (pauerswald_t cp, pauerscon_t scp)
+{
+	dbg ("auerswald_removeservice called");
+
+	/* check if we have a service allocated */
+	if (scp->id == AUH_UNASSIGNED) return;
+
+	/* If there is a device: close the channel */
+	if (cp->usbdev) {
+		/* Close the service channel inside the device */
+		int ret = auerchain_control_msg(
+		&cp->controlchain,            		/* pointer to control chain */
+		cp->usbdev,         		        /* pointer to device */
+		usb_sndctrlpipe (cp->usbdev, 0),	/* pipe to control endpoint */
+		AUV_CHANNELCTL,                         /* USB message request value */
+		AUT_WREQ,                               /* USB message request type value */
+		0x00,              // close             /* USB message value */
+		scp->id,            		        /* USB message index value */
+		NULL,                                   /* pointer to the data to send */
+		0,                                      /* length in bytes of the data to send */
+		HZ * 2);                                /* time to wait for the message to complete before timing out */
+		if (ret < 0) {
+			dbg ("auerswald_removeservice: auerchain_control_msg returned error code %d", ret);
+		}
+		else {
+			dbg ("auerswald_removeservice: channel close OK");
+		}
+	}
+
+	/* remove the service from the device */
+	cp->services[scp->id] = NULL;
+	scp->id = AUH_UNASSIGNED;
+}
+
+
+/* --------------------------------------------------------------------- */
+/* Char device functions                                                 */
+
+/* Open a new character device */
+static int auerchar_open (struct inode *inode, struct file *file)
+{
+	int dtindex = minor(inode->i_rdev) - AUER_MINOR_BASE;
+	pauerswald_t cp = NULL;
+	pauerchar_t ccp = NULL;
+        int ret;
+
+        /* minor number in range? */
+	if ((dtindex < 0) || (dtindex >= AUER_MAX_DEVICES)) {
+		return -ENODEV;
+        }
+	/* usb device available? */
+	if (down_interruptible (&dev_table_mutex)) {
+		return -ERESTARTSYS;
+	}
+	cp = dev_table[dtindex];
+	if (cp == NULL) {
+		up (&dev_table_mutex);
+		return -ENODEV;
+	}
+	if (down_interruptible (&cp->mutex)) {
+		up (&dev_table_mutex);
+		return -ERESTARTSYS;
+	}
+	up (&dev_table_mutex);
+
+	/* prevent module unloading */
+	MOD_INC_USE_COUNT;
+
+	/* we have access to the device. Now lets allocate memory */
+	ccp = (pauerchar_t) kmalloc(sizeof(auerchar_t), GFP_KERNEL);
+	if (ccp == NULL) {
+		err ("out of memory");
+		ret = -ENOMEM;
+		goto ofail;
+	}
+
+	/* Initialize device descriptor */
+	memset( ccp, 0, sizeof(auerchar_t));
+	init_MUTEX( &ccp->mutex);
+	init_MUTEX( &ccp->readmutex);
+        auerbuf_init (&ccp->bufctl);
+        ccp->scontext.id = AUH_UNASSIGNED;
+        ccp->scontext.dispatch = auerchar_ctrlread_dispatch;
+	ccp->scontext.disconnect = auerchar_disconnect;
+	init_waitqueue_head (&ccp->readwait);
+
+	ret = auerbuf_setup (&ccp->bufctl, AU_RBUFFERS, cp->maxControlLength+AUH_SIZE);
+       	if (ret) {
+		goto ofail;
+	}
+
+	cp->open_count++;
+	ccp->auerdev = cp;
+	dbg("open %s as /dev/usb/%s", cp->dev_desc, cp->name);
+	up (&cp->mutex);
+
+	/* file IO stuff */
+	file->f_pos = 0;
+	file->private_data = ccp;
+	return 0;
+
+	/* Error exit */
+ofail:	up (&cp->mutex);
+	auerchar_delete (ccp);
+  	MOD_DEC_USE_COUNT;
+	return ret;
+}
+
+
+/* IOCTL functions */
+static int auerchar_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
+{
+	pauerchar_t ccp = (pauerchar_t) file->private_data;
+	int ret = 0;
+        audevinfo_t devinfo;
+        pauerswald_t cp = NULL;
+	unsigned int u;
+        dbg ("ioctl");
+
+	/* get the mutexes */
+	if (down_interruptible (&ccp->mutex)) {
+		return -ERESTARTSYS;
+	}
+	cp = ccp->auerdev;
+	if (!cp) {
+		up (&ccp->mutex);
+                return -ENODEV;
+	}
+	if (down_interruptible (&cp->mutex)) {
+		up(&ccp->mutex);
+		return -ERESTARTSYS;
+	}
+
+	/* Check for removal */
+	if (!cp->usbdev) {
+		up(&cp->mutex);
+		up(&ccp->mutex);
+                return -ENODEV;
+	}
+
+	switch (cmd) {
+
+	/* return != 0 if Transmitt channel ready to send */
+	case IOCTL_AU_TXREADY:
+		dbg ("IOCTL_AU_TXREADY");
+		u   = ccp->auerdev
+		   && (ccp->scontext.id != AUH_UNASSIGNED)
+		   && !list_empty (&cp->bufctl.free_buff_list);
+	        ret = put_user (u, (unsigned int *) arg);
+		break;
+
+	/* return != 0 if connected to a service channel */
+	case IOCTL_AU_CONNECT:
+		dbg ("IOCTL_AU_CONNECT");
+		u = (ccp->scontext.id != AUH_UNASSIGNED);
+	        ret = put_user (u, (unsigned int *) arg);
+		break;
+
+	/* return != 0 if Receive Data available */
+	case IOCTL_AU_RXAVAIL:
+		dbg ("IOCTL_AU_RXAVAIL");
+		if (ccp->scontext.id == AUH_UNASSIGNED) {
+                        ret = -EIO;
+                        break;
+                }
+		u = 0;	/* no data */
+		if (ccp->readbuf) {
+			int restlen = ccp->readbuf->len - ccp->readoffset;
+			if (restlen > 0) u = 1;
+		}
+		if (!u) {
+        		if (!list_empty (&ccp->bufctl.rec_buff_list)) {
+				u = 1;
+			}
+		}
+	        ret = put_user (u, (unsigned int *) arg);
+		break;
+
+	/* return the max. buffer length for the device */
+	case IOCTL_AU_BUFLEN:
+		dbg ("IOCTL_AU_BUFLEN");
+		u = cp->maxControlLength;
+	        ret = put_user (u, (unsigned int *) arg);
+		break;
+
+	/* requesting a service channel */
+        case IOCTL_AU_SERVREQ:
+		dbg ("IOCTL_AU_SERVREQ");
+                /* requesting a service means: release the previous one first */
+		auerswald_removeservice (cp, &ccp->scontext);
+		/* get the channel number */
+		ret = get_user (u, (unsigned int *) arg);
+		if (ret) {
+			break;
+		}
+		if ((u < AUH_FIRSTUSERCH) || (u >= AUH_TYPESIZE)) {
+                        ret = -EIO;
+                        break;
+                }
+                dbg ("auerchar service request parameters are ok");
+		ccp->scontext.id = u;
+
+		/* request the service now */
+		ret = auerswald_addservice (cp, &ccp->scontext);
+		if (ret) {
+			/* no: revert service entry */
+                	ccp->scontext.id = AUH_UNASSIGNED;
+		}
+		break;
+
+	/* get a string descriptor for the device */
+	case IOCTL_AU_DEVINFO:
+		dbg ("IOCTL_AU_DEVINFO");
+                if (copy_from_user (&devinfo, (void *) arg, sizeof (audevinfo_t))) {
+        		ret = -EFAULT;
+	        	break;
+                }
+		u = strlen(cp->dev_desc)+1;
+		if (u > devinfo.bsize) {
+			u = devinfo.bsize;
+		}
+		ret = copy_to_user(devinfo.buf, cp->dev_desc, u);
+		break;
+
+	/* get the max. string descriptor length */
+        case IOCTL_AU_SLEN:
+		dbg ("IOCTL_AU_SLEN");
+		u = AUSI_DLEN;
+	        ret = put_user (u, (unsigned int *) arg);
+		break;
+
+	default:
+		dbg ("IOCTL_AU_UNKNOWN");
+		ret = -ENOIOCTLCMD;
+		break;
+        }
+	/* release the mutexes */
+	up(&cp->mutex);
+	up(&ccp->mutex);
+	return ret;
+}
+
+
+/* Seek is not supported */
+static loff_t auerchar_llseek (struct file *file, loff_t offset, int origin)
+{
+        dbg ("auerchar_seek");
+        return -ESPIPE;
+}
+
+
+/* Read data from the device */
+static ssize_t auerchar_read (struct file *file, char *buf, size_t count, loff_t * ppos)
+{
+        unsigned long flags;
+	pauerchar_t ccp = (pauerchar_t) file->private_data;
+        pauerbuf_t   bp = NULL;
+        dbg ("auerchar_read");
+
+	/* Error checking */
+	if (!ccp)
+		return -EIO;
+	if (*ppos)
+ 		return -ESPIPE;
+        if (count == 0)
+		return 0;
+
+	/* get the mutex */
+	if (down_interruptible (&ccp->mutex))
+		return -ERESTARTSYS;
+
+	/* Can we expect to read something? */
+	if (ccp->scontext.id == AUH_UNASSIGNED) {
+		up (&ccp->mutex);
+                return -EIO;
+	}
+
+	/* only one reader per device allowed */
+	if (down_interruptible (&ccp->readmutex)) {
+		up (&ccp->mutex);
+		return -ERESTARTSYS;
+	}
+
+	/* read data from readbuf, if available */
+doreadbuf:
+	bp = ccp->readbuf;
+	if (bp) {
+		/* read the maximum bytes */
+		int restlen = bp->len - ccp->readoffset;
+		if (restlen < 0)
+			restlen = 0;
+		if (count > restlen)
+			count = restlen;
+		if (count) {
+			if (copy_to_user (buf, bp->bufp+ccp->readoffset, count)) {
+				dbg ("auerswald_read: copy_to_user failed");
+				up (&ccp->readmutex);
+				up (&ccp->mutex);
+				return -EFAULT;
+			}
+		}
+		/* advance the read offset */
+		ccp->readoffset += count;
+		restlen -= count;
+		// reuse the read buffer
+		if (restlen <= 0) {
+			auerbuf_releasebuf (bp);
+			ccp->readbuf = NULL;
+		}
+		/* return with number of bytes read */
+		if (count) {
+			up (&ccp->readmutex);
+			up (&ccp->mutex);
+			return count;
+		}
+	}
+
+	/* a read buffer is not available. Try to get the next data block. */
+doreadlist:
+	bp = NULL;
+	spin_lock_irqsave (&ccp->bufctl.lock, flags);
+        if (!list_empty (&ccp->bufctl.rec_buff_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = ccp->bufctl.rec_buff_list.next;
+                list_del (tmp);
+                bp = list_entry (tmp, auerbuf_t, buff_list);
+        }
+        spin_unlock_irqrestore (&ccp->bufctl.lock, flags);
+
+	/* have we got data? */
+	if (bp) {
+		ccp->readbuf = bp;
+		ccp->readoffset = AUH_SIZE; /* for headerbyte */
+		goto doreadbuf;		  /* now we can read! */
+	}
+
+	/* no data available. Should we wait? */
+	if (file->f_flags & O_NONBLOCK) {
+                dbg ("No read buffer available, returning -EAGAIN");
+		up (&ccp->readmutex);
+		up (&ccp->mutex);
+                return -EAGAIN;  /* nonblocking, no data available */
+        }
+
+	/* yes, we should wait! */
+	up (&ccp->mutex); /* allow other operations while we wait */
+	interruptible_sleep_on (&ccp->readwait);
+	if (signal_pending (current)) {
+		/* waked up by a signal */
+		up (&ccp->readmutex);
+		return -ERESTARTSYS;
+	}
+
+	/* Anything left to read? */
+	if ((ccp->scontext.id == AUH_UNASSIGNED) || ccp->removed) {
+		up (&ccp->readmutex);
+		return -EIO;
+	}
+
+	if (down_interruptible (&ccp->mutex)) {
+		up (&ccp->readmutex);
+		return -ERESTARTSYS;
+	}
+
+	/* try to read the incomming data again */
+	goto doreadlist;
+}
+
+
+/* Write a data block into the right service channel of the device */
+static ssize_t auerchar_write (struct file *file, const char *buf, size_t len, loff_t *ppos)
+{
+	pauerchar_t ccp = (pauerchar_t) file->private_data;
+        pauerswald_t cp = NULL;
+        pauerbuf_t bp;
+        unsigned long flags;
+	int ret;
+
+        dbg ("auerchar_write %d bytes", len);
+
+	/* Error checking */
+	if (!ccp)
+		return -EIO;
+        if (*ppos)
+		return -ESPIPE;
+        if (len == 0)
+                return 0;
+
+write_again:
+	/* get the mutex */
+	if (down_interruptible (&ccp->mutex))
+		return -ERESTARTSYS;
+
+	/* Can we expect to write something? */
+	if (ccp->scontext.id == AUH_UNASSIGNED) {
+		up (&ccp->mutex);
+                return -EIO;
+	}
+
+	cp = ccp->auerdev;
+	if (!cp) {
+		up (&ccp->mutex);
+		return -ERESTARTSYS;
+	}
+	if (down_interruptible (&cp->mutex)) {
+		up (&ccp->mutex);
+		return -ERESTARTSYS;
+	}
+	if (!cp->usbdev) {
+		up (&cp->mutex);
+		up (&ccp->mutex);
+		return -EIO;
+	}
+	/* Try to get a buffer from the device pool.
+	   We can't use a buffer from ccp->bufctl because the write
+	   command will last beond a release() */
+	bp = NULL;
+	spin_lock_irqsave (&cp->bufctl.lock, flags);
+        if (!list_empty (&cp->bufctl.free_buff_list)) {
+                /* yes: get the entry */
+                struct list_head *tmp = cp->bufctl.free_buff_list.next;
+                list_del (tmp);
+                bp = list_entry (tmp, auerbuf_t, buff_list);
+        }
+        spin_unlock_irqrestore (&cp->bufctl.lock, flags);
+
+	/* are there any buffers left? */
+	if (!bp) {
+		up (&cp->mutex);
+		up (&ccp->mutex);
+
+		/* NONBLOCK: don't wait */
+		if (file->f_flags & O_NONBLOCK) {
+			return -EAGAIN;
+		}
+
+		/* BLOCKING: wait */
+		interruptible_sleep_on (&cp->bufferwait);
+		if (signal_pending (current)) {
+			/* waked up by a signal */
+			return -ERESTARTSYS;
+		}
+		goto write_again;
+	}
+
+	/* protect against too big write requests */
+	if (len > cp->maxControlLength) len = cp->maxControlLength;
+
+	/* Fill the buffer */
+	if (copy_from_user ( bp->bufp+AUH_SIZE, buf, len)) {
+		dbg ("copy_from_user failed");
+		auerbuf_releasebuf (bp);
+		up (&cp->mutex);
+		up (&ccp->mutex);
+		return -EIO;
+	}
+
+	/* set the header byte */
+        *(bp->bufp) = ccp->scontext.id | AUH_DIRECT | AUH_UNSPLIT;
+
+	/* Set the transfer Parameters */
+	bp->len = len+AUH_SIZE;
+        bp->dr->requesttype = AUT_WREQ;
+	bp->dr->request     = AUV_WBLOCK;
+	bp->dr->value       = cpu_to_le16 (0);
+	bp->dr->index       = cpu_to_le16 (ccp->scontext.id | AUH_DIRECT | AUH_UNSPLIT);
+	bp->dr->length      = cpu_to_le16 (len+AUH_SIZE);
+	FILL_CONTROL_URB (bp->urbp, cp->usbdev, usb_sndctrlpipe (cp->usbdev, 0),
+                   (unsigned char*)bp->dr, bp->bufp, len+AUH_SIZE,
+		    auerchar_ctrlwrite_complete, bp);
+	/* up we go */
+	ret = auerchain_submit_urb (&cp->controlchain, bp->urbp);
+	up (&cp->mutex);
+	if (ret) {
+		dbg ("auerchar_write: nonzero result of auerchain_submit_urb %d", ret);
+		auerbuf_releasebuf (bp);
+		up (&ccp->mutex);
+		return -EIO;
+	}
+	else {
+		dbg ("auerchar_write: Write OK");
+		up (&ccp->mutex);
+		return len;
+	}
+}
+
+
+/* Close a character device */
+static int auerchar_release (struct inode *inode, struct file *file)
+{
+	pauerchar_t ccp = (pauerchar_t) file->private_data;
+	pauerswald_t cp;
+	dbg("release");
+
+	/* get the mutexes */
+	if (down_interruptible (&ccp->mutex)) {
+		return -ERESTARTSYS;
+	}
+	cp = ccp->auerdev;
+	if (cp) {
+		if (down_interruptible (&cp->mutex)) {
+			up (&ccp->mutex);
+			return -ERESTARTSYS;
+		}
+		/* remove an open service */
+		auerswald_removeservice (cp, &ccp->scontext);
+		/* detach from device */
+		if ((--cp->open_count <= 0) && (cp->usbdev == NULL)) {
+			/* usb device waits for removal */
+			up (&cp->mutex);
+			auerswald_delete (cp);
+		} else {
+			up (&cp->mutex);
+		}
+		cp = NULL;
+		ccp->auerdev = NULL;
+	}
+	up (&ccp->mutex);
+	auerchar_delete (ccp);
+
+	/* release the module */
+	MOD_DEC_USE_COUNT;
+
+	return 0;
+}
+
+
+/*----------------------------------------------------------------------*/
+/* File operation structure                                             */
+static struct file_operations auerswald_fops =
+{
+	owner:		THIS_MODULE,
+	llseek:		auerchar_llseek,
+	read:		auerchar_read,
+	write:          auerchar_write,
+	ioctl:		auerchar_ioctl,
+	open:		auerchar_open,
+	release:	auerchar_release,
+};
+
+
+/* --------------------------------------------------------------------- */
+/* Special USB driver functions                                          */
+
+/* Probe if this driver wants to serve an USB device
+
+   This entry point is called whenever a new device is attached to the bus.
+   Then the device driver has to create a new instance of its internal data
+   structures for the new device.
+
+   The  dev argument specifies the device context, which contains pointers
+   to all USB descriptors. The  interface argument specifies the interface
+   number. If a USB driver wants to bind itself to a particular device and
+   interface it has to return a pointer. This pointer normally references
+   the device driver's context structure.
+
+   Probing normally is done by checking the vendor and product identifications
+   or the class and subclass definitions. If they match the interface number
+   is compared with the ones supported by the driver. When probing is done
+   class based it might be necessary to parse some more USB descriptors because
+   the device properties can differ in a wide range.
+*/
+static void *auerswald_probe (struct usb_device *usbdev, unsigned int ifnum,
+			      const struct usb_device_id *id)
+{
+	pauerswald_t cp = NULL;
+	DECLARE_WAIT_QUEUE_HEAD (wqh);
+	unsigned int dtindex;
+	unsigned int u = 0;
+	char *pbuf;
+	int ret;
+
+	dbg ("probe: vendor id 0x%x, device id 0x%x ifnum:%d",
+	     usbdev->descriptor.idVendor, usbdev->descriptor.idProduct, ifnum);
+
+	/* See if the device offered us matches that we can accept */
+	if (usbdev->descriptor.idVendor != ID_AUERSWALD) return NULL;
+
+        /* we use only the first -and only- interface */
+        if (ifnum != 0) return NULL;
+
+	/* prevent module unloading while sleeping */
+	MOD_INC_USE_COUNT;
+
+	/* allocate memory for our device and intialize it */
+	cp = kmalloc (sizeof(auerswald_t), GFP_KERNEL);
+	if (cp == NULL) {
+		err ("out of memory");
+		goto pfail;
+	}
+
+	/* Initialize device descriptor */
+	memset (cp, 0, sizeof(auerswald_t));
+	init_MUTEX (&cp->mutex);
+	cp->usbdev = usbdev;
+	auerchain_init (&cp->controlchain);
+        auerbuf_init (&cp->bufctl);
+	init_waitqueue_head (&cp->bufferwait);
+
+	/* find a free slot in the device table */
+	down (&dev_table_mutex);
+	for (dtindex = 0; dtindex < AUER_MAX_DEVICES; ++dtindex) {
+		if (dev_table[dtindex] == NULL)
+			break;
+	}
+	if ( dtindex >= AUER_MAX_DEVICES) {
+		err ("more than %d devices plugged in, can not handle this device", AUER_MAX_DEVICES);
+		up (&dev_table_mutex);
+		goto pfail;
+	}
+
+	/* Give the device a name */
+	sprintf (cp->name, AU_PREFIX "%d", dtindex);
+
+	/* Store the index */
+	cp->dtindex = dtindex;
+	dev_table[dtindex] = cp;
+	up (&dev_table_mutex);
+
+	/* initialize the devfs node for this device and register it */
+	cp->devfs = devfs_register (usb_devfs_handle, cp->name,
+				    DEVFS_FL_DEFAULT, USB_MAJOR,
+				    AUER_MINOR_BASE + dtindex,
+				    S_IFCHR | S_IRUGO | S_IWUGO,
+				    &auerswald_fops, NULL);
+
+	/* Get the usb version of the device */
+	cp->version = cp->usbdev->descriptor.bcdDevice;
+	dbg ("Version is %X", cp->version);
+
+	/* allow some time to settle the device */
+	sleep_on_timeout (&wqh, HZ / 3 );
+
+	/* Try to get a suitable textual description of the device */
+	/* Device name:*/
+	ret = usb_string( cp->usbdev, AUSI_DEVICE, cp->dev_desc, AUSI_DLEN-1);
+	if (ret >= 0) {
+		u += ret;
+		/* Append Serial Number */
+		memcpy(&cp->dev_desc[u], ",Ser# ", 6);
+		u += 6;
+		ret = usb_string( cp->usbdev, AUSI_SERIALNR, &cp->dev_desc[u], AUSI_DLEN-u-1);
+		if (ret >= 0) {
+			u += ret;
+			/* Append subscriber number */
+			memcpy(&cp->dev_desc[u], ", ", 2);
+			u += 2;
+			ret = usb_string( cp->usbdev, AUSI_MSN, &cp->dev_desc[u], AUSI_DLEN-u-1);
+			if (ret >= 0) {
+				u += ret;
+			}
+		}
+	}
+	cp->dev_desc[u] = '\0';
+	info("device is a %s", cp->dev_desc);
+
+        /* get the maximum allowed control transfer length */
+        pbuf = (char *) kmalloc (2, GFP_KERNEL);    /* use an allocated buffer because of urb target */
+        if (!pbuf) {
+		err( "out of memory");
+		goto pfail;
+	}
+        ret = usb_control_msg(cp->usbdev,           /* pointer to device */
+                usb_rcvctrlpipe( cp->usbdev, 0 ),   /* pipe to control endpoint */
+                AUV_GETINFO,                        /* USB message request value */
+                AUT_RREQ,                           /* USB message request type value */
+                0,                                  /* USB message value */
+                AUDI_MBCTRANS,                      /* USB message index value */
+                pbuf,                               /* pointer to the receive buffer */
+                2,                                  /* length of the buffer */
+                HZ * 2);                            /* time to wait for the message to complete before timing out */
+        if (ret == 2) {
+	        cp->maxControlLength = le16_to_cpup(pbuf);
+                kfree(pbuf);
+                dbg("setup: max. allowed control transfersize is %d bytes", cp->maxControlLength);
+        } else {
+                kfree(pbuf);
+                err("setup: getting max. allowed control transfer length failed with error %d", ret);
+		goto pfail;
+        }
+
+	/* allocate a chain for the control messages */
+        if (auerchain_setup (&cp->controlchain, AUCH_ELEMENTS)) {
+		err ("out of memory");
+		goto pfail;
+	}
+
+        /* allocate buffers for control messages */
+	if (auerbuf_setup (&cp->bufctl, AU_RBUFFERS, cp->maxControlLength+AUH_SIZE)) {
+		err ("out of memory");
+		goto pfail;
+	}
+
+	/* start the interrupt endpoint */
+	if (auerswald_int_open (cp)) {
+		err ("int endpoint failed");
+		goto pfail;
+	}
+
+	/* all OK */
+	return cp;
+
+	/* Error exit: clean up the memory */
+pfail:	auerswald_delete (cp);
+	MOD_DEC_USE_COUNT;
+	return NULL;
+}
+
+
+/* Disconnect driver from a served device
+
+   This function is called whenever a device which was served by this driver
+   is disconnected.
+
+   The argument  dev specifies the device context and the  driver_context
+   returns a pointer to the previously registered  driver_context of the
+   probe function. After returning from the disconnect function the USB
+   framework completly deallocates all data structures associated with
+   this device. So especially the usb_device structure must not be used
+   any longer by the usb driver.
+*/
+static void auerswald_disconnect (struct usb_device *usbdev, void *driver_context)
+{
+	pauerswald_t cp = (pauerswald_t) driver_context;
+	unsigned int u;
+
+	down (&cp->mutex);
+	info ("device /dev/usb/%s now disconnecting", cp->name);
+
+	/* remove from device table */
+	/* Nobody can open() this device any more */
+	down (&dev_table_mutex);
+	dev_table[cp->dtindex] = NULL;
+	up (&dev_table_mutex);
+
+	/* remove our devfs node */
+	/* Nobody can see this device any more */
+	devfs_unregister (cp->devfs);
+
+	/* Stop the interrupt endpoint */
+	auerswald_int_release (cp);
+
+	/* remove the control chain allocated in auerswald_probe
+	   This has the benefit of
+	   a) all pending (a)synchronous urbs are unlinked
+	   b) all buffers dealing with urbs are reclaimed
+	*/
+	auerchain_free (&cp->controlchain);
+
+	if (cp->open_count == 0) {
+		/* nobody is using this device. So we can clean up now */
+		up (&cp->mutex);/* up() is possible here because no other task
+				   can open the device (see above). I don't want
+				   to kfree() a locked mutex. */
+		auerswald_delete (cp);
+	} else {
+		/* device is used. Remove the pointer to the
+		   usb device (it's not valid any more). The last
+		   release() will do the clean up */
+		cp->usbdev = NULL;
+		up (&cp->mutex);
+		/* Terminate waiting writers */
+		wake_up (&cp->bufferwait);
+		/* Inform all waiting readers */
+		for ( u = 0; u < AUH_TYPESIZE; u++) {
+			pauerscon_t scp = cp->services[u];
+			if (scp) scp->disconnect( scp);
+		}
+	}
+
+	/* The device releases this module */
+	MOD_DEC_USE_COUNT;
+}
+
+/* Descriptor for the devices which are served by this driver.
+   NOTE: this struct is parsed by the usbmanager install scripts.
+         Don't change without caution!
+*/
+static struct usb_device_id auerswald_ids [] = {
+	{ USB_DEVICE (ID_AUERSWALD, 0x00C0) },          /* COMpact 2104 USB */
+	{ USB_DEVICE (ID_AUERSWALD, 0x00DB) },          /* COMpact 4410/2206 USB */
+	{ USB_DEVICE (ID_AUERSWALD, 0x00F1) },          /* Comfort 2000 System Telephone */
+	{ USB_DEVICE (ID_AUERSWALD, 0x00F2) },          /* Comfort 1200 System Telephone */
+        { }			                        /* Terminating entry */
+};
+
+/* Standard module device table */
+MODULE_DEVICE_TABLE (usb, auerswald_ids);
+
+/* Standard usb driver struct */
+static struct usb_driver auerswald_driver = {
+	name:		"auerswald",
+	probe:		auerswald_probe,
+	disconnect:	auerswald_disconnect,
+	fops:		&auerswald_fops,
+	minor:		AUER_MINOR_BASE,
+	id_table:	auerswald_ids,
+};
+
+
+/* --------------------------------------------------------------------- */
+/* Module loading/unloading                                              */
+
+/* Driver initialisation. Called after module loading.
+   NOTE: there is no concurrency at _init
+*/
+static int __init auerswald_init (void)
+{
+	int result;
+	dbg ("init");
+
+	/* initialize the device table */
+	memset (&dev_table, 0, sizeof(dev_table));
+	init_MUTEX (&dev_table_mutex);
+
+	/* register driver at the USB subsystem */
+	result = usb_register (&auerswald_driver);
+	if (result < 0) {
+		err ("driver could not be registered");
+		return -1;
+	}
+	return 0;
+}
+
+/* Driver deinit. Called before module removal.
+   NOTE: there is no concurrency at _cleanup
+*/
+static void __exit auerswald_cleanup (void)
+{
+	dbg ("cleanup");
+	usb_deregister (&auerswald_driver);
+}
+
+/* --------------------------------------------------------------------- */
+/* Linux device driver module description                                */
+
+MODULE_AUTHOR (DRIVER_AUTHOR);
+MODULE_DESCRIPTION (DRIVER_DESC);
+
+module_init (auerswald_init);
+module_exit (auerswald_cleanup);
+
+/* --------------------------------------------------------------------- */