/*
 * USB driver for Gigaset 307x base via direct USB connection.
 *
 * Copyright (c) 2001 by Hansjoerg Lipp <hjlipp@web.de>,
 *                       Tilman Schmidt <tilman@imap.cc>,
 *                       Stefan Eilers.
 *
 * =====================================================================
 *      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.
 * =====================================================================
 */

#include "gigaset.h"
#include <linux/usb.h>
#include <linux/module.h>
#include <linux/moduleparam.h>

/* Version Information */
#define DRIVER_AUTHOR "Tilman Schmidt <tilman@imap.cc>, Hansjoerg Lipp <hjlipp@web.de>, Stefan Eilers"
#define DRIVER_DESC "USB Driver for Gigaset 307x"


/* Module parameters */

static int startmode = SM_ISDN;
static int cidmode = 1;

module_param(startmode, int, S_IRUGO);
module_param(cidmode, int, S_IRUGO);
MODULE_PARM_DESC(startmode, "start in isdn4linux mode");
MODULE_PARM_DESC(cidmode, "Call-ID mode");

#define GIGASET_MINORS     1
#define GIGASET_MINOR      16
#define GIGASET_MODULENAME "bas_gigaset"
#define GIGASET_DEVNAME    "ttyGB"

/* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
#define IF_WRITEBUF 264

/* interrupt pipe message size according to ibid. ch. 2.2 */
#define IP_MSGSIZE 3

/* Values for the Gigaset 307x */
#define USB_GIGA_VENDOR_ID      0x0681
#define USB_3070_PRODUCT_ID     0x0001
#define USB_3075_PRODUCT_ID     0x0002
#define USB_SX303_PRODUCT_ID    0x0021
#define USB_SX353_PRODUCT_ID    0x0022

/* table of devices that work with this driver */
static const struct usb_device_id gigaset_table[] = {
        { USB_DEVICE(USB_GIGA_VENDOR_ID, USB_3070_PRODUCT_ID) },
        { USB_DEVICE(USB_GIGA_VENDOR_ID, USB_3075_PRODUCT_ID) },
        { USB_DEVICE(USB_GIGA_VENDOR_ID, USB_SX303_PRODUCT_ID) },
        { USB_DEVICE(USB_GIGA_VENDOR_ID, USB_SX353_PRODUCT_ID) },
        { } /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, gigaset_table);

/*======================= local function prototypes ==========================*/

/* function called if a new device belonging to this driver is connected */
static int gigaset_probe(struct usb_interface *interface,
                         const struct usb_device_id *id);

/* Function will be called if the device is unplugged */
static void gigaset_disconnect(struct usb_interface *interface);

/* functions called before/after suspend */
static int gigaset_suspend(struct usb_interface *intf, pm_message_t message);
static int gigaset_resume(struct usb_interface *intf);

/* functions called before/after device reset */
static int gigaset_pre_reset(struct usb_interface *intf);
static int gigaset_post_reset(struct usb_interface *intf);

static int atread_submit(struct cardstate *, int);
static void stopurbs(struct bas_bc_state *);
static int req_submit(struct bc_state *, int, int, int);
static int atwrite_submit(struct cardstate *, unsigned char *, int);
static int start_cbsend(struct cardstate *);

/*============================================================================*/

struct bas_cardstate {
        struct usb_device       *udev;          /* USB device pointer */
        struct cardstate        *cs;
        struct usb_interface    *interface;     /* interface for this device */
        unsigned char           minor;          /* starting minor number */

        struct urb              *urb_ctrl;      /* control pipe default URB */
        struct usb_ctrlrequest  dr_ctrl;
        struct timer_list       timer_ctrl;     /* control request timeout */
        int                     retry_ctrl;

        struct timer_list       timer_atrdy;    /* AT command ready timeout */
        struct urb              *urb_cmd_out;   /* for sending AT commands */
        struct usb_ctrlrequest  dr_cmd_out;
        int                     retry_cmd_out;

        struct urb              *urb_cmd_in;    /* for receiving AT replies */
        struct usb_ctrlrequest  dr_cmd_in;
        struct timer_list       timer_cmd_in;   /* receive request timeout */
        unsigned char           *rcvbuf;        /* AT reply receive buffer */

        struct urb              *urb_int_in;    /* URB for interrupt pipe */
        unsigned char           *int_in_buf;
        struct work_struct      int_in_wq;      /* for usb_clear_halt() */
        struct timer_list       timer_int_in;   /* int read retry delay */
        int                     retry_int_in;

        spinlock_t              lock;           /* locks all following */
        int                     basstate;       /* bitmap (BS_*) */
        int                     pending;        /* uncompleted base request */
        wait_queue_head_t       waitqueue;
        int                     rcvbuf_size;    /* size of AT receive buffer */
                                                /* 0: no receive in progress */
        int                     retry_cmd_in;   /* receive req retry count */
};

/* status of direct USB connection to 307x base (bits in basstate) */
#define BS_ATOPEN       0x001   /* AT channel open */
#define BS_B1OPEN       0x002   /* B channel 1 open */
#define BS_B2OPEN       0x004   /* B channel 2 open */
#define BS_ATREADY      0x008   /* base ready for AT command */
#define BS_INIT         0x010   /* base has signalled INIT_OK */
#define BS_ATTIMER      0x020   /* waiting for HD_READY_SEND_ATDATA */
#define BS_ATRDPEND     0x040   /* urb_cmd_in in use */
#define BS_ATWRPEND     0x080   /* urb_cmd_out in use */
#define BS_SUSPEND      0x100   /* USB port suspended */
#define BS_RESETTING    0x200   /* waiting for HD_RESET_INTERRUPT_PIPE_ACK */


static struct gigaset_driver *driver;

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver gigaset_usb_driver = {
        .name =         GIGASET_MODULENAME,
        .probe =        gigaset_probe,
        .disconnect =   gigaset_disconnect,
        .id_table =     gigaset_table,
        .suspend =      gigaset_suspend,
        .resume =       gigaset_resume,
        .reset_resume = gigaset_post_reset,
        .pre_reset =    gigaset_pre_reset,
        .post_reset =   gigaset_post_reset,
        .disable_hub_initiated_lpm = 1,
};

/* get message text for usb_submit_urb return code
 */
static char *get_usb_rcmsg(int rc)
{
        static char unkmsg[28];

        switch (rc) {
        case 0:
                return "success";
        case -ENOMEM:
                return "out of memory";
        case -ENODEV:
                return "device not present";
        case -ENOENT:
                return "endpoint not present";
        case -ENXIO:
                return "URB type not supported";
        case -EINVAL:
                return "invalid argument";
        case -EAGAIN:
                return "start frame too early or too much scheduled";
        case -EFBIG:
                return "too many isoc frames requested";
        case -EPIPE:
                return "endpoint stalled";
        case -EMSGSIZE:
                return "invalid packet size";
        case -ENOSPC:
                return "would overcommit USB bandwidth";
        case -ESHUTDOWN:
                return "device shut down";
        case -EPERM:
                return "reject flag set";
        case -EHOSTUNREACH:
                return "device suspended";
        default:
                snprintf(unkmsg, sizeof(unkmsg), "unknown error %d", rc);
                return unkmsg;
        }
}

/* get message text for USB status code
 */
static char *get_usb_statmsg(int status)
{
        static char unkmsg[28];

        switch (status) {
        case 0:
                return "success";
        case -ENOENT:
                return "unlinked (sync)";
        case -EINPROGRESS:
                return "URB still pending";
        case -EPROTO:
                return "bitstuff error, timeout, or unknown USB error";
        case -EILSEQ:
                return "CRC mismatch, timeout, or unknown USB error";
        case -ETIME:
                return "USB response timeout";
        case -EPIPE:
                return "endpoint stalled";
        case -ECOMM:
                return "IN buffer overrun";
        case -ENOSR:
                return "OUT buffer underrun";
        case -EOVERFLOW:
                return "endpoint babble";
        case -EREMOTEIO:
                return "short packet";
        case -ENODEV:
                return "device removed";
        case -EXDEV:
                return "partial isoc transfer";
        case -EINVAL:
                return "ISO madness";
        case -ECONNRESET:
                return "unlinked (async)";
        case -ESHUTDOWN:
                return "device shut down";
        default:
                snprintf(unkmsg, sizeof(unkmsg), "unknown status %d", status);
                return unkmsg;
        }
}

/* usb_pipetype_str
 * retrieve string representation of USB pipe type
 */
static inline char *usb_pipetype_str(int pipe)
{
        if (usb_pipeisoc(pipe))
                return "Isoc";
        if (usb_pipeint(pipe))
                return "Int";
        if (usb_pipecontrol(pipe))
                return "Ctrl";
        if (usb_pipebulk(pipe))
                return "Bulk";
        return "?";
}

/* dump_urb
 * write content of URB to syslog for debugging
 */
static inline void dump_urb(enum debuglevel level, const char *tag,
                            struct urb *urb)
{
#ifdef CONFIG_GIGASET_DEBUG
        int i;
        gig_dbg(level, "%s urb(0x%08lx)->{", tag, (unsigned long) urb);
        if (urb) {
                gig_dbg(level,
                        "  dev=0x%08lx, pipe=%s:EP%d/DV%d:%s, "
                        "hcpriv=0x%08lx, transfer_flags=0x%x,",
                        (unsigned long) urb->dev,
                        usb_pipetype_str(urb->pipe),
                        usb_pipeendpoint(urb->pipe), usb_pipedevice(urb->pipe),
                        usb_pipein(urb->pipe) ? "in" : "out",
                        (unsigned long) urb->hcpriv,
                        urb->transfer_flags);
                gig_dbg(level,
                        "  transfer_buffer=0x%08lx[%d], actual_length=%d, "
                        "setup_packet=0x%08lx,",
                        (unsigned long) urb->transfer_buffer,
                        urb->transfer_buffer_length, urb->actual_length,
                        (unsigned long) urb->setup_packet);
                gig_dbg(level,
                        "  start_frame=%d, number_of_packets=%d, interval=%d, "
                        "error_count=%d,",
                        urb->start_frame, urb->number_of_packets, urb->interval,
                        urb->error_count);
                gig_dbg(level,
                        "  context=0x%08lx, complete=0x%08lx, "
                        "iso_frame_desc[]={",
                        (unsigned long) urb->context,
                        (unsigned long) urb->complete);
                for (i = 0; i < urb->number_of_packets; i++) {
                        struct usb_iso_packet_descriptor *pifd
                                = &urb->iso_frame_desc[i];
                        gig_dbg(level,
                                "    {offset=%u, length=%u, actual_length=%u, "
                                "status=%u}",
                                pifd->offset, pifd->length, pifd->actual_length,
                                pifd->status);
                }
        }
        gig_dbg(level, "}}");
#endif
}

/* read/set modem control bits etc. (m10x only) */
static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state,
                                  unsigned new_state)
{
        return -EINVAL;
}

static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
{
        return -EINVAL;
}

static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
{
        return -EINVAL;
}

/* set/clear bits in base connection state, return previous state
 */
static inline int update_basstate(struct bas_cardstate *ucs,
                                  int set, int clear)
{
        unsigned long flags;
        int state;

        spin_lock_irqsave(&ucs->lock, flags);
        state = ucs->basstate;
        ucs->basstate = (state & ~clear) | set;
        spin_unlock_irqrestore(&ucs->lock, flags);
        return state;
}

/* error_hangup
 * hang up any existing connection because of an unrecoverable error
 * This function may be called from any context and takes care of scheduling
 * the necessary actions for execution outside of interrupt context.
 * cs->lock must not be held.
 * argument:
 *      B channel control structure
 */
static inline void error_hangup(struct bc_state *bcs)
{
        struct cardstate *cs = bcs->cs;

        gigaset_add_event(cs, &bcs->at_state, EV_HUP, NULL, 0, NULL);
        gigaset_schedule_event(cs);
}

/* error_reset
 * reset Gigaset device because of an unrecoverable error
 * This function may be called from any context, and takes care of
 * scheduling the necessary actions for execution outside of interrupt context.
 * cs->hw.bas->lock must not be held.
 * argument:
 *      controller state structure
 */
static inline void error_reset(struct cardstate *cs)
{
        /* reset interrupt pipe to recover (ignore errors) */
        update_basstate(cs->hw.bas, BS_RESETTING, 0);
        if (req_submit(cs->bcs, HD_RESET_INTERRUPT_PIPE, 0, BAS_TIMEOUT))
                /* submission failed, escalate to USB port reset */
                usb_queue_reset_device(cs->hw.bas->interface);
}

/* check_pending
 * check for completion of pending control request
 * parameter:
 *      ucs     hardware specific controller state structure
 */
static void check_pending(struct bas_cardstate *ucs)
{
        unsigned long flags;

        spin_lock_irqsave(&ucs->lock, flags);
        switch (ucs->pending) {
        case 0:
                break;
        case HD_OPEN_ATCHANNEL:
                if (ucs->basstate & BS_ATOPEN)
                        ucs->pending = 0;
                break;
        case HD_OPEN_B1CHANNEL:
                if (ucs->basstate & BS_B1OPEN)
                        ucs->pending = 0;
                break;
        case HD_OPEN_B2CHANNEL:
                if (ucs->basstate & BS_B2OPEN)
                        ucs->pending = 0;
                break;
        case HD_CLOSE_ATCHANNEL:
                if (!(ucs->basstate & BS_ATOPEN))
                        ucs->pending = 0;
                break;
        case HD_CLOSE_B1CHANNEL:
                if (!(ucs->basstate & BS_B1OPEN))
                        ucs->pending = 0;
                break;
        case HD_CLOSE_B2CHANNEL:
                if (!(ucs->basstate & BS_B2OPEN))
                        ucs->pending = 0;
                break;
        case HD_DEVICE_INIT_ACK:                /* no reply expected */
                ucs->pending = 0;
                break;
        case HD_RESET_INTERRUPT_PIPE:
                if (!(ucs->basstate & BS_RESETTING))
                        ucs->pending = 0;
                break;
        /*
         * HD_READ_ATMESSAGE and HD_WRITE_ATMESSAGE are handled separately
         * and should never end up here
         */
        default:
                dev_warn(&ucs->interface->dev,
                         "unknown pending request 0x%02x cleared\n",
                         ucs->pending);
                ucs->pending = 0;
        }

        if (!ucs->pending)
                del_timer(&ucs->timer_ctrl);

        spin_unlock_irqrestore(&ucs->lock, flags);
}

/* cmd_in_timeout
 * timeout routine for command input request
 * argument:
 *      controller state structure
 */
static void cmd_in_timeout(struct timer_list *t)
{
        struct bas_cardstate *ucs = from_timer(ucs, t, timer_cmd_in);
        struct cardstate *cs = ucs->cs;
        int rc;

        if (!ucs->rcvbuf_size) {
                gig_dbg(DEBUG_USBREQ, "%s: no receive in progress", __func__);
                return;
        }

        if (ucs->retry_cmd_in++ >= BAS_RETRY) {
                dev_err(cs->dev,
                        "control read: timeout, giving up after %d tries\n",
                        ucs->retry_cmd_in);
                kfree(ucs->rcvbuf);
                ucs->rcvbuf = NULL;
                ucs->rcvbuf_size = 0;
                error_reset(cs);
                return;
        }

        gig_dbg(DEBUG_USBREQ, "%s: timeout, retry %d",
                __func__, ucs->retry_cmd_in);
        rc = atread_submit(cs, BAS_TIMEOUT);
        if (rc < 0) {
                kfree(ucs->rcvbuf);
                ucs->rcvbuf = NULL;
                ucs->rcvbuf_size = 0;
                if (rc != -ENODEV)
                        error_reset(cs);
        }
}

/* read_ctrl_callback
 * USB completion handler for control pipe input
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block
 *              urb->context = inbuf structure for controller state
 */
static void read_ctrl_callback(struct urb *urb)
{
        struct inbuf_t *inbuf = urb->context;
        struct cardstate *cs = inbuf->cs;
        struct bas_cardstate *ucs = cs->hw.bas;
        int status = urb->status;
        unsigned numbytes;
        int rc;

        update_basstate(ucs, 0, BS_ATRDPEND);
        wake_up(&ucs->waitqueue);
        del_timer(&ucs->timer_cmd_in);

        switch (status) {
        case 0:                         /* normal completion */
                numbytes = urb->actual_length;
                if (unlikely(numbytes != ucs->rcvbuf_size)) {
                        dev_warn(cs->dev,
                                 "control read: received %d chars, expected %d\n",
                                 numbytes, ucs->rcvbuf_size);
                        if (numbytes > ucs->rcvbuf_size)
                                numbytes = ucs->rcvbuf_size;
                }

                /* copy received bytes to inbuf, notify event layer */
                if (gigaset_fill_inbuf(inbuf, ucs->rcvbuf, numbytes)) {
                        gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
                        gigaset_schedule_event(cs);
                }
                break;

        case -ENOENT:                   /* cancelled */
        case -ECONNRESET:               /* cancelled (async) */
        case -EINPROGRESS:              /* pending */
        case -ENODEV:                   /* device removed */
        case -ESHUTDOWN:                /* device shut down */
                /* no further action necessary */
                gig_dbg(DEBUG_USBREQ, "%s: %s",
                        __func__, get_usb_statmsg(status));
                break;

        default:                        /* other errors: retry */
                if (ucs->retry_cmd_in++ < BAS_RETRY) {
                        gig_dbg(DEBUG_USBREQ, "%s: %s, retry %d", __func__,
                                get_usb_statmsg(status), ucs->retry_cmd_in);
                        rc = atread_submit(cs, BAS_TIMEOUT);
                        if (rc >= 0)
                                /* successfully resubmitted, skip freeing */
                                return;
                        if (rc == -ENODEV)
                                /* disconnect, no further action necessary */
                                break;
                }
                dev_err(cs->dev, "control read: %s, giving up after %d tries\n",
                        get_usb_statmsg(status), ucs->retry_cmd_in);
                error_reset(cs);
        }

        /* read finished, free buffer */
        kfree(ucs->rcvbuf);
        ucs->rcvbuf = NULL;
        ucs->rcvbuf_size = 0;
}

/* atread_submit
 * submit an HD_READ_ATMESSAGE command URB and optionally start a timeout
 * parameters:
 *      cs      controller state structure
 *      timeout timeout in 1/10 sec., 0: none
 * return value:
 *      0 on success
 *      -EBUSY if another request is pending
 *      any URB submission error code
 */
static int atread_submit(struct cardstate *cs, int timeout)
{
        struct bas_cardstate *ucs = cs->hw.bas;
        int basstate;
        int ret;

        gig_dbg(DEBUG_USBREQ, "-------> HD_READ_ATMESSAGE (%d)",
                ucs->rcvbuf_size);

        basstate = update_basstate(ucs, BS_ATRDPEND, 0);
        if (basstate & BS_ATRDPEND) {
                dev_err(cs->dev,
                        "could not submit HD_READ_ATMESSAGE: URB busy\n");
                return -EBUSY;
        }

        if (basstate & BS_SUSPEND) {
                dev_notice(cs->dev,
                           "HD_READ_ATMESSAGE not submitted, "
                           "suspend in progress\n");
                update_basstate(ucs, 0, BS_ATRDPEND);
                /* treat like disconnect */
                return -ENODEV;
        }

        ucs->dr_cmd_in.bRequestType = IN_VENDOR_REQ;
        ucs->dr_cmd_in.bRequest = HD_READ_ATMESSAGE;
        ucs->dr_cmd_in.wValue = 0;
        ucs->dr_cmd_in.wIndex = 0;
        ucs->dr_cmd_in.wLength = cpu_to_le16(ucs->rcvbuf_size);
        usb_fill_control_urb(ucs->urb_cmd_in, ucs->udev,
                             usb_rcvctrlpipe(ucs->udev, 0),
                             (unsigned char *) &ucs->dr_cmd_in,
                             ucs->rcvbuf, ucs->rcvbuf_size,
                             read_ctrl_callback, cs->inbuf);

        ret = usb_submit_urb(ucs->urb_cmd_in, GFP_ATOMIC);
        if (ret != 0) {
                update_basstate(ucs, 0, BS_ATRDPEND);
                dev_err(cs->dev, "could not submit HD_READ_ATMESSAGE: %s\n",
                        get_usb_rcmsg(ret));
                return ret;
        }

        if (timeout > 0) {
                gig_dbg(DEBUG_USBREQ, "setting timeout of %d/10 secs", timeout);
                mod_timer(&ucs->timer_cmd_in, jiffies + timeout * HZ / 10);
        }
        return 0;
}

/* int_in_work
 * workqueue routine to clear halt on interrupt in endpoint
 */

static void int_in_work(struct work_struct *work)
{
        struct bas_cardstate *ucs =
                container_of(work, struct bas_cardstate, int_in_wq);
        struct urb *urb = ucs->urb_int_in;
        struct cardstate *cs = urb->context;
        int rc;

        /* clear halt condition */
        rc = usb_clear_halt(ucs->udev, urb->pipe);
        gig_dbg(DEBUG_USBREQ, "clear_halt: %s", get_usb_rcmsg(rc));
        if (rc == 0)
                /* success, resubmit interrupt read URB */
                rc = usb_submit_urb(urb, GFP_ATOMIC);

        switch (rc) {
        case 0:         /* success */
        case -ENODEV:   /* device gone */
        case -EINVAL:   /* URB already resubmitted, or terminal badness */
                break;
        default:        /* failure: try to recover by resetting the device */
                dev_err(cs->dev, "clear halt failed: %s\n", get_usb_rcmsg(rc));
                rc = usb_lock_device_for_reset(ucs->udev, ucs->interface);
                if (rc == 0) {
                        rc = usb_reset_device(ucs->udev);
                        usb_unlock_device(ucs->udev);
                }
        }
        ucs->retry_int_in = 0;
}

/* int_in_resubmit
 * timer routine for interrupt read delayed resubmit
 * argument:
 *      controller state structure
 */
static void int_in_resubmit(struct timer_list *t)
{
        struct bas_cardstate *ucs = from_timer(ucs, t, timer_int_in);
        struct cardstate *cs = ucs->cs;
        int rc;

        if (ucs->retry_int_in++ >= BAS_RETRY) {
                dev_err(cs->dev, "interrupt read: giving up after %d tries\n",
                        ucs->retry_int_in);
                usb_queue_reset_device(ucs->interface);
                return;
        }

        gig_dbg(DEBUG_USBREQ, "%s: retry %d", __func__, ucs->retry_int_in);
        rc = usb_submit_urb(ucs->urb_int_in, GFP_ATOMIC);
        if (rc != 0 && rc != -ENODEV) {
                dev_err(cs->dev, "could not resubmit interrupt URB: %s\n",
                        get_usb_rcmsg(rc));
                usb_queue_reset_device(ucs->interface);
        }
}

/* read_int_callback
 * USB completion handler for interrupt pipe input
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block
 *              urb->context = controller state structure
 */
static void read_int_callback(struct urb *urb)
{
        struct cardstate *cs = urb->context;
        struct bas_cardstate *ucs = cs->hw.bas;
        struct bc_state *bcs;
        int status = urb->status;
        unsigned long flags;
        int rc;
        unsigned l;
        int channel;

        switch (status) {
        case 0:                 /* success */
                ucs->retry_int_in = 0;
                break;
        case -EPIPE:                    /* endpoint stalled */
                schedule_work(&ucs->int_in_wq);
                /* fall through */
        case -ENOENT:                   /* cancelled */
        case -ECONNRESET:               /* cancelled (async) */
        case -EINPROGRESS:              /* pending */
        case -ENODEV:                   /* device removed */
        case -ESHUTDOWN:                /* device shut down */
                /* no further action necessary */
                gig_dbg(DEBUG_USBREQ, "%s: %s",
                        __func__, get_usb_statmsg(status));
                return;
        case -EPROTO:                   /* protocol error or unplug */
        case -EILSEQ:
        case -ETIME:
                /* resubmit after delay */
                gig_dbg(DEBUG_USBREQ, "%s: %s",
                        __func__, get_usb_statmsg(status));
                mod_timer(&ucs->timer_int_in, jiffies + HZ / 10);
                return;
        default:                /* other errors: just resubmit */
                dev_warn(cs->dev, "interrupt read: %s\n",
                         get_usb_statmsg(status));
                goto resubmit;
        }

        /* drop incomplete packets even if the missing bytes wouldn't matter */
        if (unlikely(urb->actual_length < IP_MSGSIZE)) {
                dev_warn(cs->dev, "incomplete interrupt packet (%d bytes)\n",
                         urb->actual_length);
                goto resubmit;
        }

        l = (unsigned) ucs->int_in_buf[1] +
                (((unsigned) ucs->int_in_buf[2]) << 8);

        gig_dbg(DEBUG_USBREQ, "<-------%d: 0x%02x (%u [0x%02x 0x%02x])",
                urb->actual_length, (int)ucs->int_in_buf[0], l,
                (int)ucs->int_in_buf[1], (int)ucs->int_in_buf[2]);

        channel = 0;

        switch (ucs->int_in_buf[0]) {
        case HD_DEVICE_INIT_OK:
                update_basstate(ucs, BS_INIT, 0);
                break;

        case HD_READY_SEND_ATDATA:
                del_timer(&ucs->timer_atrdy);
                update_basstate(ucs, BS_ATREADY, BS_ATTIMER);
                start_cbsend(cs);
                break;

        case HD_OPEN_B2CHANNEL_ACK:
                ++channel;
        case HD_OPEN_B1CHANNEL_ACK:
                bcs = cs->bcs + channel;
                update_basstate(ucs, BS_B1OPEN << channel, 0);
                gigaset_bchannel_up(bcs);
                break;

        case HD_OPEN_ATCHANNEL_ACK:
                update_basstate(ucs, BS_ATOPEN, 0);
                start_cbsend(cs);
                break;

        case HD_CLOSE_B2CHANNEL_ACK:
                ++channel;
        case HD_CLOSE_B1CHANNEL_ACK:
                bcs = cs->bcs + channel;
                update_basstate(ucs, 0, BS_B1OPEN << channel);
                stopurbs(bcs->hw.bas);
                gigaset_bchannel_down(bcs);
                break;

        case HD_CLOSE_ATCHANNEL_ACK:
                update_basstate(ucs, 0, BS_ATOPEN);
                break;

        case HD_B2_FLOW_CONTROL:
                ++channel;
        case HD_B1_FLOW_CONTROL:
                bcs = cs->bcs + channel;
                atomic_add((l - BAS_NORMFRAME) * BAS_CORRFRAMES,
                           &bcs->hw.bas->corrbytes);
                gig_dbg(DEBUG_ISO,
                        "Flow control (channel %d, sub %d): 0x%02x => %d",
                        channel, bcs->hw.bas->numsub, l,
                        atomic_read(&bcs->hw.bas->corrbytes));
                break;

        case HD_RECEIVEATDATA_ACK:      /* AT response ready to be received */
                if (!l) {
                        dev_warn(cs->dev,
                                 "HD_RECEIVEATDATA_ACK with length 0 ignored\n");
                        break;
                }
                spin_lock_irqsave(&cs->lock, flags);
                if (ucs->basstate & BS_ATRDPEND) {
                        spin_unlock_irqrestore(&cs->lock, flags);
                        dev_warn(cs->dev,
                                 "HD_RECEIVEATDATA_ACK(%d) during HD_READ_ATMESSAGE(%d) ignored\n",
                                 l, ucs->rcvbuf_size);
                        break;
                }
                if (ucs->rcvbuf_size) {
                        /* throw away previous buffer - we have no queue */
                        dev_err(cs->dev,
                                "receive AT data overrun, %d bytes lost\n",
                                ucs->rcvbuf_size);
                        kfree(ucs->rcvbuf);
                        ucs->rcvbuf_size = 0;
                }
                ucs->rcvbuf = kmalloc(l, GFP_ATOMIC);
                if (ucs->rcvbuf == NULL) {
                        spin_unlock_irqrestore(&cs->lock, flags);
                        dev_err(cs->dev, "out of memory receiving AT data\n");
                        break;
                }
                ucs->rcvbuf_size = l;
                ucs->retry_cmd_in = 0;
                rc = atread_submit(cs, BAS_TIMEOUT);
                if (rc < 0) {
                        kfree(ucs->rcvbuf);
                        ucs->rcvbuf = NULL;
                        ucs->rcvbuf_size = 0;
                }
                spin_unlock_irqrestore(&cs->lock, flags);
                if (rc < 0 && rc != -ENODEV)
                        error_reset(cs);
                break;

        case HD_RESET_INTERRUPT_PIPE_ACK:
                update_basstate(ucs, 0, BS_RESETTING);
                dev_notice(cs->dev, "interrupt pipe reset\n");
                break;

        case HD_SUSPEND_END:
                gig_dbg(DEBUG_USBREQ, "HD_SUSPEND_END");
                break;

        default:
                dev_warn(cs->dev,
                         "unknown Gigaset signal 0x%02x (%u) ignored\n",
                         (int) ucs->int_in_buf[0], l);
        }

        check_pending(ucs);
        wake_up(&ucs->waitqueue);

resubmit:
        rc = usb_submit_urb(urb, GFP_ATOMIC);
        if (unlikely(rc != 0 && rc != -ENODEV)) {
                dev_err(cs->dev, "could not resubmit interrupt URB: %s\n",
                        get_usb_rcmsg(rc));
                error_reset(cs);
        }
}

/* read_iso_callback
 * USB completion handler for B channel isochronous input
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block of completed request
 *              urb->context = bc_state structure
 */
static void read_iso_callback(struct urb *urb)
{
        struct bc_state *bcs;
        struct bas_bc_state *ubc;
        int status = urb->status;
        unsigned long flags;
        int i, rc;

        /* status codes not worth bothering the tasklet with */
        if (unlikely(status == -ENOENT ||
                     status == -ECONNRESET ||
                     status == -EINPROGRESS ||
                     status == -ENODEV ||
                     status == -ESHUTDOWN)) {
                gig_dbg(DEBUG_ISO, "%s: %s",
                        __func__, get_usb_statmsg(status));
                return;
        }

        bcs = urb->context;
        ubc = bcs->hw.bas;

        spin_lock_irqsave(&ubc->isoinlock, flags);
        if (likely(ubc->isoindone == NULL)) {
                /* pass URB to tasklet */
                ubc->isoindone = urb;
                ubc->isoinstatus = status;
                tasklet_hi_schedule(&ubc->rcvd_tasklet);
        } else {
                /* tasklet still busy, drop data and resubmit URB */
                gig_dbg(DEBUG_ISO, "%s: overrun", __func__);
                ubc->loststatus = status;
                for (i = 0; i < BAS_NUMFRAMES; i++) {
                        ubc->isoinlost += urb->iso_frame_desc[i].actual_length;
                        if (unlikely(urb->iso_frame_desc[i].status != 0 &&
                                     urb->iso_frame_desc[i].status != -EINPROGRESS))
                                ubc->loststatus = urb->iso_frame_desc[i].status;
                        urb->iso_frame_desc[i].status = 0;
                        urb->iso_frame_desc[i].actual_length = 0;
                }
                if (likely(ubc->running)) {
                        /* urb->dev is clobbered by USB subsystem */
                        urb->dev = bcs->cs->hw.bas->udev;
                        urb->transfer_flags = URB_ISO_ASAP;
                        urb->number_of_packets = BAS_NUMFRAMES;
                        rc = usb_submit_urb(urb, GFP_ATOMIC);
                        if (unlikely(rc != 0 && rc != -ENODEV)) {
                                dev_err(bcs->cs->dev,
                                        "could not resubmit isoc read URB: %s\n",
                                        get_usb_rcmsg(rc));
                                dump_urb(DEBUG_ISO, "isoc read", urb);
                                error_hangup(bcs);
                        }
                }
        }
        spin_unlock_irqrestore(&ubc->isoinlock, flags);
}

/* write_iso_callback
 * USB completion handler for B channel isochronous output
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block of completed request
 *              urb->context = isow_urbctx_t structure
 */
static void write_iso_callback(struct urb *urb)
{
        struct isow_urbctx_t *ucx;
        struct bas_bc_state *ubc;
        int status = urb->status;
        unsigned long flags;

        /* status codes not worth bothering the tasklet with */
        if (unlikely(status == -ENOENT ||
                     status == -ECONNRESET ||
                     status == -EINPROGRESS ||
                     status == -ENODEV ||
                     status == -ESHUTDOWN)) {
                gig_dbg(DEBUG_ISO, "%s: %s",
                        __func__, get_usb_statmsg(status));
                return;
        }

        /* pass URB context to tasklet */
        ucx = urb->context;
        ubc = ucx->bcs->hw.bas;
        ucx->status = status;

        spin_lock_irqsave(&ubc->isooutlock, flags);
        ubc->isooutovfl = ubc->isooutdone;
        ubc->isooutdone = ucx;
        spin_unlock_irqrestore(&ubc->isooutlock, flags);
        tasklet_hi_schedule(&ubc->sent_tasklet);
}

/* starturbs
 * prepare and submit USB request blocks for isochronous input and output
 * argument:
 *      B channel control structure
 * return value:
 *      0 on success
 *      < 0 on error (no URBs submitted)
 */
static int starturbs(struct bc_state *bcs)
{
        struct bas_bc_state *ubc = bcs->hw.bas;
        struct urb *urb;
        int j, k;
        int rc;

        /* initialize L2 reception */
        if (bcs->proto2 == L2_HDLC)
                bcs->inputstate |= INS_flag_hunt;

        /* submit all isochronous input URBs */
        ubc->running = 1;
        for (k = 0; k < BAS_INURBS; k++) {
                urb = ubc->isoinurbs[k];
                if (!urb) {
                        rc = -EFAULT;
                        goto error;
                }

                urb->dev = bcs->cs->hw.bas->udev;
                urb->pipe = usb_rcvisocpipe(urb->dev, 3 + 2 * bcs->channel);
                urb->transfer_flags = URB_ISO_ASAP;
                urb->transfer_buffer = ubc->isoinbuf + k * BAS_INBUFSIZE;
                urb->transfer_buffer_length = BAS_INBUFSIZE;
                urb->number_of_packets = BAS_NUMFRAMES;
                urb->interval = BAS_FRAMETIME;
                urb->complete = read_iso_callback;
                urb->context = bcs;
                for (j = 0; j < BAS_NUMFRAMES; j++) {
                        urb->iso_frame_desc[j].offset = j * BAS_MAXFRAME;
                        urb->iso_frame_desc[j].length = BAS_MAXFRAME;
                        urb->iso_frame_desc[j].status = 0;
                        urb->iso_frame_desc[j].actual_length = 0;
                }

                dump_urb(DEBUG_ISO, "Initial isoc read", urb);
                rc = usb_submit_urb(urb, GFP_ATOMIC);
                if (rc != 0)
                        goto error;
        }

        /* initialize L2 transmission */
        gigaset_isowbuf_init(ubc->isooutbuf, PPP_FLAG);

        /* set up isochronous output URBs for flag idling */
        for (k = 0; k < BAS_OUTURBS; ++k) {
                urb = ubc->isoouturbs[k].urb;
                if (!urb) {
                        rc = -EFAULT;
                        goto error;
                }
                urb->dev = bcs->cs->hw.bas->udev;
                urb->pipe = usb_sndisocpipe(urb->dev, 4 + 2 * bcs->channel);
                urb->transfer_flags = URB_ISO_ASAP;
                urb->transfer_buffer = ubc->isooutbuf->data;
                urb->transfer_buffer_length = sizeof(ubc->isooutbuf->data);
                urb->number_of_packets = BAS_NUMFRAMES;
                urb->interval = BAS_FRAMETIME;
                urb->complete = write_iso_callback;
                urb->context = &ubc->isoouturbs[k];
                for (j = 0; j < BAS_NUMFRAMES; ++j) {
                        urb->iso_frame_desc[j].offset = BAS_OUTBUFSIZE;
                        urb->iso_frame_desc[j].length = BAS_NORMFRAME;
                        urb->iso_frame_desc[j].status = 0;
                        urb->iso_frame_desc[j].actual_length = 0;
                }
                ubc->isoouturbs[k].limit = -1;
        }

        /* keep one URB free, submit the others */
        for (k = 0; k < BAS_OUTURBS - 1; ++k) {
                dump_urb(DEBUG_ISO, "Initial isoc write", urb);
                rc = usb_submit_urb(ubc->isoouturbs[k].urb, GFP_ATOMIC);
                if (rc != 0)
                        goto error;
        }
        dump_urb(DEBUG_ISO, "Initial isoc write (free)", urb);
        ubc->isooutfree = &ubc->isoouturbs[BAS_OUTURBS - 1];
        ubc->isooutdone = ubc->isooutovfl = NULL;
        return 0;
error:
        stopurbs(ubc);
        return rc;
}

/* stopurbs
 * cancel the USB request blocks for isochronous input and output
 * errors are silently ignored
 * argument:
 *      B channel control structure
 */
static void stopurbs(struct bas_bc_state *ubc)
{
        int k, rc;

        ubc->running = 0;

        for (k = 0; k < BAS_INURBS; ++k) {
                rc = usb_unlink_urb(ubc->isoinurbs[k]);
                gig_dbg(DEBUG_ISO,
                        "%s: isoc input URB %d unlinked, result = %s",
                        __func__, k, get_usb_rcmsg(rc));
        }

        for (k = 0; k < BAS_OUTURBS; ++k) {
                rc = usb_unlink_urb(ubc->isoouturbs[k].urb);
                gig_dbg(DEBUG_ISO,
                        "%s: isoc output URB %d unlinked, result = %s",
                        __func__, k, get_usb_rcmsg(rc));
        }
}

/* Isochronous Write - Bottom Half */
/* =============================== */

/* submit_iso_write_urb
 * fill and submit the next isochronous write URB
 * parameters:
 *      ucx     context structure containing URB
 * return value:
 *      number of frames submitted in URB
 *      0 if URB not submitted because no data available (isooutbuf busy)
 *      error code < 0 on error
 */
static int submit_iso_write_urb(struct isow_urbctx_t *ucx)
{
        struct urb *urb = ucx->urb;
        struct bas_bc_state *ubc = ucx->bcs->hw.bas;
        struct usb_iso_packet_descriptor *ifd;
        int corrbytes, nframe, rc;

        /* urb->dev is clobbered by USB subsystem */
        urb->dev = ucx->bcs->cs->hw.bas->udev;
        urb->transfer_flags = URB_ISO_ASAP;
        urb->transfer_buffer = ubc->isooutbuf->data;
        urb->transfer_buffer_length = sizeof(ubc->isooutbuf->data);

        for (nframe = 0; nframe < BAS_NUMFRAMES; nframe++) {
                ifd = &urb->iso_frame_desc[nframe];

                /* compute frame length according to flow control */
                ifd->length = BAS_NORMFRAME;
                corrbytes = atomic_read(&ubc->corrbytes);
                if (corrbytes != 0) {
                        gig_dbg(DEBUG_ISO, "%s: corrbytes=%d",
                                __func__, corrbytes);
                        if (corrbytes > BAS_HIGHFRAME - BAS_NORMFRAME)
                                corrbytes = BAS_HIGHFRAME - BAS_NORMFRAME;
                        else if (corrbytes < BAS_LOWFRAME - BAS_NORMFRAME)
                                corrbytes = BAS_LOWFRAME - BAS_NORMFRAME;
                        ifd->length += corrbytes;
                        atomic_add(-corrbytes, &ubc->corrbytes);
                }

                /* retrieve block of data to send */
                rc = gigaset_isowbuf_getbytes(ubc->isooutbuf, ifd->length);
                if (rc < 0) {
                        if (rc == -EBUSY) {
                                gig_dbg(DEBUG_ISO,
                                        "%s: buffer busy at frame %d",
                                        __func__, nframe);
                                /* tasklet will be restarted from
                                   gigaset_isoc_send_skb() */
                        } else {
                                dev_err(ucx->bcs->cs->dev,
                                        "%s: buffer error %d at frame %d\n",
                                        __func__, rc, nframe);
                                return rc;
                        }
                        break;
                }
                ifd->offset = rc;
                ucx->limit = ubc->isooutbuf->nextread;
                ifd->status = 0;
                ifd->actual_length = 0;
        }
        if (unlikely(nframe == 0))
                return 0;       /* no data to send */
        urb->number_of_packets = nframe;

        rc = usb_submit_urb(urb, GFP_ATOMIC);
        if (unlikely(rc)) {
                if (rc == -ENODEV)
                        /* device removed - give up silently */
                        gig_dbg(DEBUG_ISO, "%s: disconnected", __func__);
                else
                        dev_err(ucx->bcs->cs->dev,
                                "could not submit isoc write URB: %s\n",
                                get_usb_rcmsg(rc));
                return rc;
        }
        ++ubc->numsub;
        return nframe;
}

/* write_iso_tasklet
 * tasklet scheduled when an isochronous output URB from the Gigaset device
 * has completed
 * parameter:
 *      data    B channel state structure
 */
static void write_iso_tasklet(unsigned long data)
{
        struct bc_state *bcs = (struct bc_state *) data;
        struct bas_bc_state *ubc = bcs->hw.bas;
        struct cardstate *cs = bcs->cs;
        struct isow_urbctx_t *done, *next, *ovfl;
        struct urb *urb;
        int status;
        struct usb_iso_packet_descriptor *ifd;
        unsigned long flags;
        int i;
        struct sk_buff *skb;
        int len;
        int rc;

        /* loop while completed URBs arrive in time */
        for (;;) {
                if (unlikely(!(ubc->running))) {
                        gig_dbg(DEBUG_ISO, "%s: not running", __func__);
                        return;
                }

                /* retrieve completed URBs */
                spin_lock_irqsave(&ubc->isooutlock, flags);
                done = ubc->isooutdone;
                ubc->isooutdone = NULL;
                ovfl = ubc->isooutovfl;
                ubc->isooutovfl = NULL;
                spin_unlock_irqrestore(&ubc->isooutlock, flags);
                if (ovfl) {
                        dev_err(cs->dev, "isoc write underrun\n");
                        error_hangup(bcs);
                        break;
                }
                if (!done)
                        break;

                /* submit free URB if available */
                spin_lock_irqsave(&ubc->isooutlock, flags);
                next = ubc->isooutfree;
                ubc->isooutfree = NULL;
                spin_unlock_irqrestore(&ubc->isooutlock, flags);
                if (next) {
                        rc = submit_iso_write_urb(next);
                        if (unlikely(rc <= 0 && rc != -ENODEV)) {
                                /* could not submit URB, put it back */
                                spin_lock_irqsave(&ubc->isooutlock, flags);
                                if (ubc->isooutfree == NULL) {
                                        ubc->isooutfree = next;
                                        next = NULL;
                                }
                                spin_unlock_irqrestore(&ubc->isooutlock, flags);
                                if (next) {
                                        /* couldn't put it back */
                                        dev_err(cs->dev,
                                                "losing isoc write URB\n");
                                        error_hangup(bcs);
                                }
                        }
                }

                /* process completed URB */
                urb = done->urb;
                status = done->status;
                switch (status) {
                case -EXDEV:                    /* partial completion */
                        gig_dbg(DEBUG_ISO, "%s: URB partially completed",
                                __func__);
                        /* fall through - what's the difference anyway? */
                case 0:                         /* normal completion */
                        /* inspect individual frames
                         * assumptions (for lack of documentation):
                         * - actual_length bytes of first frame in error are
                         *   successfully sent
                         * - all following frames are not sent at all
                         */
                        for (i = 0; i < BAS_NUMFRAMES; i++) {
                                ifd = &urb->iso_frame_desc[i];
                                if (ifd->status ||
                                    ifd->actual_length != ifd->length) {
                                        dev_warn(cs->dev,
                                                 "isoc write: frame %d[%d/%d]: %s\n",
                                                 i, ifd->actual_length,
                                                 ifd->length,
                                                 get_usb_statmsg(ifd->status));
                                        break;
                                }
                        }
                        break;
                case -EPIPE:                    /* stall - probably underrun */
                        dev_err(cs->dev, "isoc write: stalled\n");
                        error_hangup(bcs);
                        break;
                default:                        /* other errors */
                        dev_warn(cs->dev, "isoc write: %s\n",
                                 get_usb_statmsg(status));
                }

                /* mark the write buffer area covered by this URB as free */
                if (done->limit >= 0)
                        ubc->isooutbuf->read = done->limit;

                /* mark URB as free */
                spin_lock_irqsave(&ubc->isooutlock, flags);
                next = ubc->isooutfree;
                ubc->isooutfree = done;
                spin_unlock_irqrestore(&ubc->isooutlock, flags);
                if (next) {
                        /* only one URB still active - resubmit one */
                        rc = submit_iso_write_urb(next);
                        if (unlikely(rc <= 0 && rc != -ENODEV)) {
                                /* couldn't submit */
                                error_hangup(bcs);
                        }
                }
        }

        /* process queued SKBs */
        while ((skb = skb_dequeue(&bcs->squeue))) {
                /* copy to output buffer, doing L2 encapsulation */
                len = skb->len;
                if (gigaset_isoc_buildframe(bcs, skb->data, len) == -EAGAIN) {
                        /* insufficient buffer space, push back onto queue */
                        skb_queue_head(&bcs->squeue, skb);
                        gig_dbg(DEBUG_ISO, "%s: skb requeued, qlen=%d",
                                __func__, skb_queue_len(&bcs->squeue));
                        break;
                }
                skb_pull(skb, len);
                gigaset_skb_sent(bcs, skb);
                dev_kfree_skb_any(skb);
        }
}

/* Isochronous Read - Bottom Half */
/* ============================== */

/* read_iso_tasklet
 * tasklet scheduled when an isochronous input URB from the Gigaset device
 * has completed
 * parameter:
 *      data    B channel state structure
 */
static void read_iso_tasklet(unsigned long data)
{
        struct bc_state *bcs = (struct bc_state *) data;
        struct bas_bc_state *ubc = bcs->hw.bas;
        struct cardstate *cs = bcs->cs;
        struct urb *urb;
        int status;
        struct usb_iso_packet_descriptor *ifd;
        char *rcvbuf;
        unsigned long flags;
        int totleft, numbytes, offset, frame, rc;

        /* loop while more completed URBs arrive in the meantime */
        for (;;) {
                /* retrieve URB */
                spin_lock_irqsave(&ubc->isoinlock, flags);
                urb = ubc->isoindone;
                if (!urb) {
                        spin_unlock_irqrestore(&ubc->isoinlock, flags);
                        return;
                }
                status = ubc->isoinstatus;
                ubc->isoindone = NULL;
                if (unlikely(ubc->loststatus != -EINPROGRESS)) {
                        dev_warn(cs->dev,
                                 "isoc read overrun, URB dropped (status: %s, %d bytes)\n",
                                 get_usb_statmsg(ubc->loststatus),
                                 ubc->isoinlost);
                        ubc->loststatus = -EINPROGRESS;
                }
                spin_unlock_irqrestore(&ubc->isoinlock, flags);

                if (unlikely(!(ubc->running))) {
                        gig_dbg(DEBUG_ISO,
                                "%s: channel not running, "
                                "dropped URB with status: %s",
                                __func__, get_usb_statmsg(status));
                        return;
                }

                switch (status) {
                case 0:                         /* normal completion */
                        break;
                case -EXDEV:                    /* inspect individual frames
                                                   (we do that anyway) */
                        gig_dbg(DEBUG_ISO, "%s: URB partially completed",
                                __func__);
                        break;
                case -ENOENT:
                case -ECONNRESET:
                case -EINPROGRESS:
                        gig_dbg(DEBUG_ISO, "%s: %s",
                                __func__, get_usb_statmsg(status));
                        continue;               /* -> skip */
                case -EPIPE:
                        dev_err(cs->dev, "isoc read: stalled\n");
                        error_hangup(bcs);
                        continue;               /* -> skip */
                default:                        /* other error */
                        dev_warn(cs->dev, "isoc read: %s\n",
                                 get_usb_statmsg(status));
                        goto error;
                }

                rcvbuf = urb->transfer_buffer;
                totleft = urb->actual_length;
                for (frame = 0; totleft > 0 && frame < BAS_NUMFRAMES; frame++) {
                        ifd = &urb->iso_frame_desc[frame];
                        numbytes = ifd->actual_length;
                        switch (ifd->status) {
                        case 0:                 /* success */
                                break;
                        case -EPROTO:           /* protocol error or unplug */
                        case -EILSEQ:
                        case -ETIME:
                                /* probably just disconnected, ignore */
                                gig_dbg(DEBUG_ISO,
                                        "isoc read: frame %d[%d]: %s\n",
                                        frame, numbytes,
                                        get_usb_statmsg(ifd->status));
                                break;
                        default:                /* other error */
                                /* report, assume transferred bytes are ok */
                                dev_warn(cs->dev,
                                         "isoc read: frame %d[%d]: %s\n",
                                         frame, numbytes,
                                         get_usb_statmsg(ifd->status));
                        }
                        if (unlikely(numbytes > BAS_MAXFRAME))
                                dev_warn(cs->dev,
                                         "isoc read: frame %d[%d]: %s\n",
                                         frame, numbytes,
                                         "exceeds max frame size");
                        if (unlikely(numbytes > totleft)) {
                                dev_warn(cs->dev,
                                         "isoc read: frame %d[%d]: %s\n",
                                         frame, numbytes,
                                         "exceeds total transfer length");
                                numbytes = totleft;
                        }
                        offset = ifd->offset;
                        if (unlikely(offset + numbytes > BAS_INBUFSIZE)) {
                                dev_warn(cs->dev,
                                         "isoc read: frame %d[%d]: %s\n",
                                         frame, numbytes,
                                         "exceeds end of buffer");
                                numbytes = BAS_INBUFSIZE - offset;
                        }
                        gigaset_isoc_receive(rcvbuf + offset, numbytes, bcs);
                        totleft -= numbytes;
                }
                if (unlikely(totleft > 0))
                        dev_warn(cs->dev, "isoc read: %d data bytes missing\n",
                                 totleft);

error:
                /* URB processed, resubmit */
                for (frame = 0; frame < BAS_NUMFRAMES; frame++) {
                        urb->iso_frame_desc[frame].status = 0;
                        urb->iso_frame_desc[frame].actual_length = 0;
                }
                /* urb->dev is clobbered by USB subsystem */
                urb->dev = bcs->cs->hw.bas->udev;
                urb->transfer_flags = URB_ISO_ASAP;
                urb->number_of_packets = BAS_NUMFRAMES;
                rc = usb_submit_urb(urb, GFP_ATOMIC);
                if (unlikely(rc != 0 && rc != -ENODEV)) {
                        dev_err(cs->dev,
                                "could not resubmit isoc read URB: %s\n",
                                get_usb_rcmsg(rc));
                        dump_urb(DEBUG_ISO, "resubmit isoc read", urb);
                        error_hangup(bcs);
                }
        }
}

/* Channel Operations */
/* ================== */

/* req_timeout
 * timeout routine for control output request
 * argument:
 *      controller state structure
 */
static void req_timeout(struct timer_list *t)
{
        struct bas_cardstate *ucs = from_timer(ucs, t, timer_ctrl);
        struct cardstate *cs = ucs->cs;
        int pending;
        unsigned long flags;

        check_pending(ucs);

        spin_lock_irqsave(&ucs->lock, flags);
        pending = ucs->pending;
        ucs->pending = 0;
        spin_unlock_irqrestore(&ucs->lock, flags);

        switch (pending) {
        case 0:                                 /* no pending request */
                gig_dbg(DEBUG_USBREQ, "%s: no request pending", __func__);
                break;

        case HD_OPEN_ATCHANNEL:
                dev_err(cs->dev, "timeout opening AT channel\n");
                error_reset(cs);
                break;

        case HD_OPEN_B1CHANNEL:
                dev_err(cs->dev, "timeout opening channel 1\n");
                error_hangup(&cs->bcs[0]);
                break;

        case HD_OPEN_B2CHANNEL:
                dev_err(cs->dev, "timeout opening channel 2\n");
                error_hangup(&cs->bcs[1]);
                break;

        case HD_CLOSE_ATCHANNEL:
                dev_err(cs->dev, "timeout closing AT channel\n");
                error_reset(cs);
                break;

        case HD_CLOSE_B1CHANNEL:
                dev_err(cs->dev, "timeout closing channel 1\n");
                error_reset(cs);
                break;

        case HD_CLOSE_B2CHANNEL:
                dev_err(cs->dev, "timeout closing channel 2\n");
                error_reset(cs);
                break;

        case HD_RESET_INTERRUPT_PIPE:
                /* error recovery escalation */
                dev_err(cs->dev,
                        "reset interrupt pipe timeout, attempting USB reset\n");
                usb_queue_reset_device(ucs->interface);
                break;

        default:
                dev_warn(cs->dev, "request 0x%02x timed out, clearing\n",
                         pending);
        }

        wake_up(&ucs->waitqueue);
}

/* write_ctrl_callback
 * USB completion handler for control pipe output
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block of completed request
 *              urb->context = hardware specific controller state structure
 */
static void write_ctrl_callback(struct urb *urb)
{
        struct bas_cardstate *ucs = urb->context;
        int status = urb->status;
        int rc;
        unsigned long flags;

        /* check status */
        switch (status) {
        case 0:                                 /* normal completion */
                spin_lock_irqsave(&ucs->lock, flags);
                switch (ucs->pending) {
                case HD_DEVICE_INIT_ACK:        /* no reply expected */
                        del_timer(&ucs->timer_ctrl);
                        ucs->pending = 0;
                        break;
                }
                spin_unlock_irqrestore(&ucs->lock, flags);
                return;

        case -ENOENT:                   /* cancelled */
        case -ECONNRESET:               /* cancelled (async) */
        case -EINPROGRESS:              /* pending */
        case -ENODEV:                   /* device removed */
        case -ESHUTDOWN:                /* device shut down */
                /* ignore silently */
                gig_dbg(DEBUG_USBREQ, "%s: %s",
                        __func__, get_usb_statmsg(status));
                break;

        default:                                /* any failure */
                /* don't retry if suspend requested */
                if (++ucs->retry_ctrl > BAS_RETRY ||
                    (ucs->basstate & BS_SUSPEND)) {
                        dev_err(&ucs->interface->dev,
                                "control request 0x%02x failed: %s\n",
                                ucs->dr_ctrl.bRequest,
                                get_usb_statmsg(status));
                        break;          /* give up */
                }
                dev_notice(&ucs->interface->dev,
                           "control request 0x%02x: %s, retry %d\n",
                           ucs->dr_ctrl.bRequest, get_usb_statmsg(status),
                           ucs->retry_ctrl);
                /* urb->dev is clobbered by USB subsystem */
                urb->dev = ucs->udev;
                rc = usb_submit_urb(urb, GFP_ATOMIC);
                if (unlikely(rc)) {
                        dev_err(&ucs->interface->dev,
                                "could not resubmit request 0x%02x: %s\n",
                                ucs->dr_ctrl.bRequest, get_usb_rcmsg(rc));
                        break;
                }
                /* resubmitted */
                return;
        }

        /* failed, clear pending request */
        spin_lock_irqsave(&ucs->lock, flags);
        del_timer(&ucs->timer_ctrl);
        ucs->pending = 0;
        spin_unlock_irqrestore(&ucs->lock, flags);
        wake_up(&ucs->waitqueue);
}

/* req_submit
 * submit a control output request without message buffer to the Gigaset base
 * and optionally start a timeout
 * parameters:
 *      bcs     B channel control structure
 *      req     control request code (HD_*)
 *      val     control request parameter value (set to 0 if unused)
 *      timeout timeout in seconds (0: no timeout)
 * return value:
 *      0 on success
 *      -EBUSY if another request is pending
 *      any URB submission error code
 */
static int req_submit(struct bc_state *bcs, int req, int val, int timeout)
{
        struct bas_cardstate *ucs = bcs->cs->hw.bas;
        int ret;
        unsigned long flags;

        gig_dbg(DEBUG_USBREQ, "-------> 0x%02x (%d)", req, val);

        spin_lock_irqsave(&ucs->lock, flags);
        if (ucs->pending) {
                spin_unlock_irqrestore(&ucs->lock, flags);
                dev_err(bcs->cs->dev,
                        "submission of request 0x%02x failed: "
                        "request 0x%02x still pending\n",
                        req, ucs->pending);
                return -EBUSY;
        }

        ucs->dr_ctrl.bRequestType = OUT_VENDOR_REQ;
        ucs->dr_ctrl.bRequest = req;
        ucs->dr_ctrl.wValue = cpu_to_le16(val);
        ucs->dr_ctrl.wIndex = 0;
        ucs->dr_ctrl.wLength = 0;
        usb_fill_control_urb(ucs->urb_ctrl, ucs->udev,
                             usb_sndctrlpipe(ucs->udev, 0),
                             (unsigned char *) &ucs->dr_ctrl, NULL, 0,
                             write_ctrl_callback, ucs);
        ucs->retry_ctrl = 0;
        ret = usb_submit_urb(ucs->urb_ctrl, GFP_ATOMIC);
        if (unlikely(ret)) {
                dev_err(bcs->cs->dev, "could not submit request 0x%02x: %s\n",
                        req, get_usb_rcmsg(ret));
                spin_unlock_irqrestore(&ucs->lock, flags);
                return ret;
        }
        ucs->pending = req;

        if (timeout > 0) {
                gig_dbg(DEBUG_USBREQ, "setting timeout of %d/10 secs", timeout);
                mod_timer(&ucs->timer_ctrl, jiffies + timeout * HZ / 10);
        }

        spin_unlock_irqrestore(&ucs->lock, flags);
        return 0;
}

/* gigaset_init_bchannel
 * called by common.c to connect a B channel
 * initialize isochronous I/O and tell the Gigaset base to open the channel
 * argument:
 *      B channel control structure
 * return value:
 *      0 on success, error code < 0 on error
 */
static int gigaset_init_bchannel(struct bc_state *bcs)
{
        struct cardstate *cs = bcs->cs;
        int req, ret;
        unsigned long flags;

        spin_lock_irqsave(&cs->lock, flags);
        if (unlikely(!cs->connected)) {
                gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
                spin_unlock_irqrestore(&cs->lock, flags);
                return -ENODEV;
        }

        if (cs->hw.bas->basstate & BS_SUSPEND) {
                dev_notice(cs->dev,
                           "not starting isoc I/O, suspend in progress\n");
                spin_unlock_irqrestore(&cs->lock, flags);
                return -EHOSTUNREACH;
        }

        ret = starturbs(bcs);
        if (ret < 0) {
                spin_unlock_irqrestore(&cs->lock, flags);
                dev_err(cs->dev,
                        "could not start isoc I/O for channel B%d: %s\n",
                        bcs->channel + 1,
                        ret == -EFAULT ? "null URB" : get_usb_rcmsg(ret));
                if (ret != -ENODEV)
                        error_hangup(bcs);
                return ret;
        }

        req = bcs->channel ? HD_OPEN_B2CHANNEL : HD_OPEN_B1CHANNEL;
        ret = req_submit(bcs, req, 0, BAS_TIMEOUT);
        if (ret < 0) {
                dev_err(cs->dev, "could not open channel B%d\n",
                        bcs->channel + 1);
                stopurbs(bcs->hw.bas);
        }

        spin_unlock_irqrestore(&cs->lock, flags);
        if (ret < 0 && ret != -ENODEV)
                error_hangup(bcs);
        return ret;
}

/* gigaset_close_bchannel
 * called by common.c to disconnect a B channel
 * tell the Gigaset base to close the channel
 * stopping isochronous I/O and LL notification will be done when the
 * acknowledgement for the close arrives
 * argument:
 *      B channel control structure
 * return value:
 *      0 on success, error code < 0 on error
 */
static int gigaset_close_bchannel(struct bc_state *bcs)
{
        struct cardstate *cs = bcs->cs;
        int req, ret;
        unsigned long flags;

        spin_lock_irqsave(&cs->lock, flags);
        if (unlikely(!cs->connected)) {
                spin_unlock_irqrestore(&cs->lock, flags);
                gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
                return -ENODEV;
        }

        if (!(cs->hw.bas->basstate & (bcs->channel ? BS_B2OPEN : BS_B1OPEN))) {
                /* channel not running: just signal common.c */
                spin_unlock_irqrestore(&cs->lock, flags);
                gigaset_bchannel_down(bcs);
                return 0;
        }

        /* channel running: tell device to close it */
        req = bcs->channel ? HD_CLOSE_B2CHANNEL : HD_CLOSE_B1CHANNEL;
        ret = req_submit(bcs, req, 0, BAS_TIMEOUT);
        if (ret < 0)
                dev_err(cs->dev, "closing channel B%d failed\n",
                        bcs->channel + 1);

        spin_unlock_irqrestore(&cs->lock, flags);
        return ret;
}

/* Device Operations */
/* ================= */

/* complete_cb
 * unqueue first command buffer from queue, waking any sleepers
 * must be called with cs->cmdlock held
 * parameter:
 *      cs      controller state structure
 */
static void complete_cb(struct cardstate *cs)
{
        struct cmdbuf_t *cb = cs->cmdbuf;

        /* unqueue completed buffer */
        cs->cmdbytes -= cs->curlen;
        gig_dbg(DEBUG_OUTPUT, "write_command: sent %u bytes, %u left",
                cs->curlen, cs->cmdbytes);
        if (cb->next != NULL) {
                cs->cmdbuf = cb->next;
                cs->cmdbuf->prev = NULL;
                cs->curlen = cs->cmdbuf->len;
        } else {
                cs->cmdbuf = NULL;
                cs->lastcmdbuf = NULL;
                cs->curlen = 0;
        }

        if (cb->wake_tasklet)
                tasklet_schedule(cb->wake_tasklet);

        kfree(cb);
}

/* write_command_callback
 * USB completion handler for AT command transmission
 * called by the USB subsystem in interrupt context
 * parameter:
 *      urb     USB request block of completed request
 *              urb->context = controller state structure
 */
static void write_command_callback(struct urb *urb)
{
        struct cardstate *cs = urb->context;
        struct bas_cardstate *ucs = cs->hw.bas;
        int status = urb->status;
        unsigned long flags;

        update_basstate(ucs, 0, BS_ATWRPEND);
        wake_up(&ucs->waitqueue);

        /* check status */
        switch (status) {
        case 0:                                 /* normal completion */
                break;
        case -ENOENT:                   /* cancelled */
        case -ECONNRESET:               /* cancelled (async) */
        case -EINPROGRESS:              /* pending */
        case -ENODEV:                   /* device removed */
        case -ESHUTDOWN:                /* device shut down */
                /* ignore silently */
                gig_dbg(DEBUG_USBREQ, "%s: %s",
                        __func__, get_usb_statmsg(status));
                return;
        default:                                /* any failure */
                if (++ucs->retry_cmd_out > BAS_RETRY) {
                        dev_warn(cs->dev,
                                 "command write: %s, "
                                 "giving up after %d retries\n",
                                 get_usb_statmsg(status),
                                 ucs->retry_cmd_out);
                        break;
                }
                if (ucs->basstate & BS_SUSPEND) {
                        dev_warn(cs->dev,
                                 "command write: %s, "
                                 "won't retry - suspend requested\n",
                                 get_usb_statmsg(status));
                        break;
                }
                if (cs->cmdbuf == NULL) {
                        dev_warn(cs->dev,
                                 "command write: %s, "
                                 "cannot retry - cmdbuf gone\n",
                                 get_usb_statmsg(status));
                        break;
                }
                dev_notice(cs->dev, "command write: %s, retry %d\n",
                           get_usb_statmsg(status), ucs->retry_cmd_out);
                if (atwrite_submit(cs, cs->cmdbuf->buf, cs->cmdbuf->len) >= 0)
                        /* resubmitted - bypass regular exit block */
                        return;
                /* command send failed, assume base still waiting */
                update_basstate(ucs, BS_ATREADY, 0);
        }

        spin_lock_irqsave(&cs->cmdlock, flags);
        if (cs->cmdbuf != NULL)
                complete_cb(cs);
        spin_unlock_irqrestore(&cs->cmdlock, flags);
}

/* atrdy_timeout
 * timeout routine for AT command transmission
 * argument:
 *      controller state structure
 */
static void atrdy_timeout(struct timer_list *t)
{
        struct bas_cardstate *ucs = from_timer(ucs, t, timer_atrdy);
        struct cardstate *cs = ucs->cs;

        dev_warn(cs->dev, "timeout waiting for HD_READY_SEND_ATDATA\n");

        /* fake the missing signal - what else can I do? */
        update_basstate(ucs, BS_ATREADY, BS_ATTIMER);
        start_cbsend(cs);
}

/* atwrite_submit
 * submit an HD_WRITE_ATMESSAGE command URB
 * parameters:
 *      cs      controller state structure
 *      buf     buffer containing command to send
 *      len     length of command to send
 * return value:
 *      0 on success
 *      -EBUSY if another request is pending
 *      any URB submission error code
 */
static int atwrite_submit(struct cardstate *cs, unsigned char *buf, int len)
{
        struct bas_cardstate *ucs = cs->hw.bas;
        int rc;

        gig_dbg(DEBUG_USBREQ, "-------> HD_WRITE_ATMESSAGE (%d)", len);

        if (update_basstate(ucs, BS_ATWRPEND, 0) & BS_ATWRPEND) {
                dev_err(cs->dev,
                        "could not submit HD_WRITE_ATMESSAGE: URB busy\n");
                return -EBUSY;
        }

        ucs->dr_cmd_out.bRequestType = OUT_VENDOR_REQ;
        ucs->dr_cmd_out.bRequest = HD_WRITE_ATMESSAGE;
        ucs->dr_cmd_out.wValue = 0;
        ucs->dr_cmd_out.wIndex = 0;
        ucs->dr_cmd_out.wLength = cpu_to_le16(len);
        usb_fill_control_urb(ucs->urb_cmd_out, ucs->udev,
                             usb_sndctrlpipe(ucs->udev, 0),
                             (unsigned char *) &ucs->dr_cmd_out, buf, len,
                             write_command_callback, cs);
        rc = usb_submit_urb(ucs->urb_cmd_out, GFP_ATOMIC);
        if (unlikely(rc)) {
                update_basstate(ucs, 0, BS_ATWRPEND);
                dev_err(cs->dev, "could not submit HD_WRITE_ATMESSAGE: %s\n",
                        get_usb_rcmsg(rc));
                return rc;
        }

        /* submitted successfully, start timeout if necessary */
        if (!(update_basstate(ucs, BS_ATTIMER, BS_ATREADY) & BS_ATTIMER)) {
                gig_dbg(DEBUG_OUTPUT, "setting ATREADY timeout of %d/10 secs",
                        ATRDY_TIMEOUT);
                mod_timer(&ucs->timer_atrdy, jiffies + ATRDY_TIMEOUT * HZ / 10);
        }
        return 0;
}

/* start_cbsend
 * start transmission of AT command queue if necessary
 * parameter:
 *      cs              controller state structure
 * return value:
 *      0 on success
 *      error code < 0 on error
 */
static int start_cbsend(struct cardstate *cs)
{
        struct cmdbuf_t *cb;
        struct bas_cardstate *ucs = cs->hw.bas;
        unsigned long flags;
        int rc;
        int retval = 0;

        /* check if suspend requested */
        if (ucs->basstate & BS_SUSPEND) {
                gig_dbg(DEBUG_OUTPUT, "suspending");
                return -EHOSTUNREACH;
        }

        /* check if AT channel is open */
        if (!(ucs->basstate & BS_ATOPEN)) {
                gig_dbg(DEBUG_OUTPUT, "AT channel not open");
                rc = req_submit(cs->bcs, HD_OPEN_ATCHANNEL, 0, BAS_TIMEOUT);
                if (rc < 0) {
                        /* flush command queue */
                        spin_lock_irqsave(&cs->cmdlock, flags);
                        while (cs->cmdbuf != NULL)
                                complete_cb(cs);
                        spin_unlock_irqrestore(&cs->cmdlock, flags);
                }
                return rc;
        }

        /* try to send first command in queue */
        spin_lock_irqsave(&cs->cmdlock, flags);

        while ((cb = cs->cmdbuf) != NULL && (ucs->basstate & BS_ATREADY)) {
                ucs->retry_cmd_out = 0;
                rc = atwrite_submit(cs, cb->buf, cb->len);
                if (unlikely(rc)) {
                        retval = rc;
                        complete_cb(cs);
                }
        }

        spin_unlock_irqrestore(&cs->cmdlock, flags);
        return retval;
}

/* gigaset_write_cmd
 * This function is called by the device independent part of the driver
 * to transmit an AT command string to the Gigaset device.
 * It encapsulates the device specific method for transmission over the
 * direct USB connection to the base.
 * The command string is added to the queue of commands to send, and
 * USB transmission is started if necessary.
 * parameters:
 *      cs              controller state structure
 *      cb              command buffer structure
 * return value:
 *      number of bytes queued on success
 *      error code < 0 on error
 */
static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb)
{
        unsigned long flags;
        int rc;

        gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
                           DEBUG_TRANSCMD : DEBUG_LOCKCMD,
                           "CMD Transmit", cb->len, cb->buf);

        /* translate "+++" escape sequence sent as a single separate command
         * into "close AT channel" command for error recovery
         * The next command will reopen the AT channel automatically.
         */
        if (cb->len == 3 && !memcmp(cb->buf, "+++", 3)) {
                /* If an HD_RECEIVEATDATA_ACK message remains unhandled
                 * because of an error, the base never sends another one.
                 * The response channel is thus effectively blocked.
                 * Closing and reopening the AT channel does *not* clear
                 * this condition.
                 * As a stopgap measure, submit a zero-length AT read
                 * before closing the AT channel. This has the undocumented
                 * effect of triggering a new HD_RECEIVEATDATA_ACK message
                 * from the base if necessary.
                 * The subsequent AT channel close then discards any pending
                 * messages.
                 */
                spin_lock_irqsave(&cs->lock, flags);
                if (!(cs->hw.bas->basstate & BS_ATRDPEND)) {
                        kfree(cs->hw.bas->rcvbuf);
                        cs->hw.bas->rcvbuf = NULL;
                        cs->hw.bas->rcvbuf_size = 0;
                        cs->hw.bas->retry_cmd_in = 0;

                        atread_submit(cs, 0);
                }
                spin_unlock_irqrestore(&cs->lock, flags);

                rc = req_submit(cs->bcs, HD_CLOSE_ATCHANNEL, 0, BAS_TIMEOUT);
                if (cb->wake_tasklet)
                        tasklet_schedule(cb->wake_tasklet);
                if (!rc)
                        rc = cb->len;
                kfree(cb);
                return rc;
        }

        spin_lock_irqsave(&cs->cmdlock, flags);
        cb->prev = cs->lastcmdbuf;
        if (cs->lastcmdbuf)
                cs->lastcmdbuf->next = cb;
        else {
                cs->cmdbuf = cb;
                cs->curlen = cb->len;
        }
        cs->cmdbytes += cb->len;
        cs->lastcmdbuf = cb;
        spin_unlock_irqrestore(&cs->cmdlock, flags);

        spin_lock_irqsave(&cs->lock, flags);
        if (unlikely(!cs->connected)) {
                spin_unlock_irqrestore(&cs->lock, flags);
                gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
                /* flush command queue */
                spin_lock_irqsave(&cs->cmdlock, flags);
                while (cs->cmdbuf != NULL)
                        complete_cb(cs);
                spin_unlock_irqrestore(&cs->cmdlock, flags);
                return -ENODEV;
        }
        rc = start_cbsend(cs);
        spin_unlock_irqrestore(&cs->lock, flags);
        return rc < 0 ? rc : cb->len;
}

/* gigaset_write_room
 * tty_driver.write_room interface routine
 * return number of characters the driver will accept to be written via
 * gigaset_write_cmd
 * parameter:
 *      controller state structure
 * return value:
 *      number of characters
 */
static int gigaset_write_room(struct cardstate *cs)
{
        return IF_WRITEBUF;
}

/* gigaset_chars_in_buffer
 * tty_driver.chars_in_buffer interface routine
 * return number of characters waiting to be sent
 * parameter:
 *      controller state structure
 * return value:
 *      number of characters
 */
static int gigaset_chars_in_buffer(struct cardstate *cs)
{
        return cs->cmdbytes;
}

/* gigaset_brkchars
 * implementation of ioctl(GIGASET_BRKCHARS)
 * parameter:
 *      controller state structure
 * return value:
 *      -EINVAL (unimplemented function)
 */
static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
{
        return -EINVAL;
}


/* Device Initialization/Shutdown */
/* ============================== */

/* Free hardware dependent part of the B channel structure
 * parameter:
 *      bcs     B channel structure
 */
static void gigaset_freebcshw(struct bc_state *bcs)
{
        struct bas_bc_state *ubc = bcs->hw.bas;
        int i;

        if (!ubc)
                return;

        /* kill URBs and tasklets before freeing - better safe than sorry */
        ubc->running = 0;
        gig_dbg(DEBUG_INIT, "%s: killing isoc URBs", __func__);
        for (i = 0; i < BAS_OUTURBS; ++i) {
                usb_kill_urb(ubc->isoouturbs[i].urb);
                usb_free_urb(ubc->isoouturbs[i].urb);
        }
        for (i = 0; i < BAS_INURBS; ++i) {
                usb_kill_urb(ubc->isoinurbs[i]);
                usb_free_urb(ubc->isoinurbs[i]);
        }
        tasklet_kill(&ubc->sent_tasklet);
        tasklet_kill(&ubc->rcvd_tasklet);
        kfree(ubc->isooutbuf);
        kfree(ubc);
        bcs->hw.bas = NULL;
}

/* Initialize hardware dependent part of the B channel structure
 * parameter:
 *      bcs     B channel structure
 * return value:
 *      0 on success, error code < 0 on failure
 */
static int gigaset_initbcshw(struct bc_state *bcs)
{
        int i;
        struct bas_bc_state *ubc;

        bcs->hw.bas = ubc = kmalloc(sizeof(struct bas_bc_state), GFP_KERNEL);
        if (!ubc) {
                pr_err("out of memory\n");
                return -ENOMEM;
        }

        ubc->running = 0;
        atomic_set(&ubc->corrbytes, 0);
        spin_lock_init(&ubc->isooutlock);
        for (i = 0; i < BAS_OUTURBS; ++i) {
                ubc->isoouturbs[i].urb = NULL;
                ubc->isoouturbs[i].bcs = bcs;
        }
        ubc->isooutdone = ubc->isooutfree = ubc->isooutovfl = NULL;
        ubc->numsub = 0;
        ubc->isooutbuf = kmalloc(sizeof(struct isowbuf_t), GFP_KERNEL);
        if (!ubc->isooutbuf) {
                pr_err("out of memory\n");
                kfree(ubc);
                bcs->hw.bas = NULL;
                return -ENOMEM;
        }
        tasklet_init(&ubc->sent_tasklet,
                     write_iso_tasklet, (unsigned long) bcs);

        spin_lock_init(&ubc->isoinlock);
        for (i = 0; i < BAS_INURBS; ++i)
                ubc->isoinurbs[i] = NULL;
        ubc->isoindone = NULL;
        ubc->loststatus = -EINPROGRESS;
        ubc->isoinlost = 0;
        ubc->seqlen = 0;
        ubc->inbyte = 0;
        ubc->inbits = 0;
        ubc->goodbytes = 0;
        ubc->alignerrs = 0;
        ubc->fcserrs = 0;
        ubc->frameerrs = 0;
        ubc->giants = 0;
        ubc->runts = 0;
        ubc->aborts = 0;
        ubc->shared0s = 0;
        ubc->stolen0s = 0;
        tasklet_init(&ubc->rcvd_tasklet,
                     read_iso_tasklet, (unsigned long) bcs);
        return 0;
}

static void gigaset_reinitbcshw(struct bc_state *bcs)
{
        struct bas_bc_state *ubc = bcs->hw.bas;

        bcs->hw.bas->running = 0;
        atomic_set(&bcs->hw.bas->corrbytes, 0);
        bcs->hw.bas->numsub = 0;
        spin_lock_init(&ubc->isooutlock);
        spin_lock_init(&ubc->isoinlock);
        ubc->loststatus = -EINPROGRESS;
}

static void gigaset_freecshw(struct cardstate *cs)
{
        /* timers, URBs and rcvbuf are disposed of in disconnect */
        kfree(cs->hw.bas->int_in_buf);
        kfree(cs->hw.bas);
        cs->hw.bas = NULL;
}

/* Initialize hardware dependent part of the cardstate structure
 * parameter:
 *      cs      cardstate structure
 * return value:
 *      0 on success, error code < 0 on failure
 */
static int gigaset_initcshw(struct cardstate *cs)
{
        struct bas_cardstate *ucs;

        cs->hw.bas = ucs = kzalloc(sizeof(*ucs), GFP_KERNEL);
        if (!ucs) {
                pr_err("out of memory\n");
                return -ENOMEM;
        }
        ucs->int_in_buf = kmalloc(IP_MSGSIZE, GFP_KERNEL);
        if (!ucs->int_in_buf) {
                kfree(ucs);
                pr_err("out of memory\n");
                return -ENOMEM;
        }

        spin_lock_init(&ucs->lock);
        ucs->cs = cs;
        timer_setup(&ucs->timer_ctrl, req_timeout, 0);
        timer_setup(&ucs->timer_atrdy, atrdy_timeout, 0);
        timer_setup(&ucs->timer_cmd_in, cmd_in_timeout, 0);
        timer_setup(&ucs->timer_int_in, int_in_resubmit, 0);
        init_waitqueue_head(&ucs->waitqueue);
        INIT_WORK(&ucs->int_in_wq, int_in_work);

        return 0;
}

/* freeurbs
 * unlink and deallocate all URBs unconditionally
 * caller must make sure that no commands are still in progress
 * parameter:
 *      cs      controller state structure
 */
static void freeurbs(struct cardstate *cs)
{
        struct bas_cardstate *ucs = cs->hw.bas;
        struct bas_bc_state *ubc;
        int i, j;

        gig_dbg(DEBUG_INIT, "%s: killing URBs", __func__);
        for (j = 0; j < BAS_CHANNELS; ++j) {
                ubc = cs->bcs[j].hw.bas;
                for (i = 0; i < BAS_OUTURBS; ++i) {
                        usb_kill_urb(ubc->isoouturbs[i].urb);
                        usb_free_urb(ubc->isoouturbs[i].urb);
                        ubc->isoouturbs[i].urb = NULL;
                }
                for (i = 0; i < BAS_INURBS; ++i) {
                        usb_kill_urb(ubc->isoinurbs[i]);
                        usb_free_urb(ubc->isoinurbs[i]);
                        ubc->isoinurbs[i] = NULL;
                }
        }
        usb_kill_urb(ucs->urb_int_in);
        usb_free_urb(ucs->urb_int_in);
        ucs->urb_int_in = NULL;
        usb_kill_urb(ucs->urb_cmd_out);
        usb_free_urb(ucs->urb_cmd_out);
        ucs->urb_cmd_out = NULL;
        usb_kill_urb(ucs->urb_cmd_in);
        usb_free_urb(ucs->urb_cmd_in);
        ucs->urb_cmd_in = NULL;
        usb_kill_urb(ucs->urb_ctrl);
        usb_free_urb(ucs->urb_ctrl);
        ucs->urb_ctrl = NULL;
}

/* gigaset_probe
 * This function is called when a new USB device is connected.
 * It checks whether the new device is handled by this driver.
 */
static int gigaset_probe(struct usb_interface *interface,
                         const struct usb_device_id *id)
{
        struct usb_host_interface *hostif;
        struct usb_device *udev = interface_to_usbdev(interface);
        struct cardstate *cs = NULL;
        struct bas_cardstate *ucs = NULL;
        struct bas_bc_state *ubc;
        struct usb_endpoint_descriptor *endpoint;
        int i, j;
        int rc;

        gig_dbg(DEBUG_INIT,
                "%s: Check if device matches .. (Vendor: 0x%x, Product: 0x%x)",
                __func__, le16_to_cpu(udev->descriptor.idVendor),
                le16_to_cpu(udev->descriptor.idProduct));

        /* set required alternate setting */
        hostif = interface->cur_altsetting;
        if (hostif->desc.bAlternateSetting != 3) {
                gig_dbg(DEBUG_INIT,
                        "%s: wrong alternate setting %d - trying to switch",
                        __func__, hostif->desc.bAlternateSetting);
                if (usb_set_interface(udev, hostif->desc.bInterfaceNumber, 3)
                    < 0) {
                        dev_warn(&udev->dev, "usb_set_interface failed, "
                                 "device %d interface %d altsetting %d\n",
                                 udev->devnum, hostif->desc.bInterfaceNumber,
                                 hostif->desc.bAlternateSetting);
                        return -ENODEV;
                }
                hostif = interface->cur_altsetting;
        }

        /* Reject application specific interfaces
         */
        if (hostif->desc.bInterfaceClass != 255) {
                dev_warn(&udev->dev, "%s: bInterfaceClass == %d\n",
                         __func__, hostif->desc.bInterfaceClass);
                return -ENODEV;
        }

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

        dev_info(&udev->dev,
                 "%s: Device matched (Vendor: 0x%x, Product: 0x%x)\n",
                 __func__, le16_to_cpu(udev->descriptor.idVendor),
                 le16_to_cpu(udev->descriptor.idProduct));

        /* allocate memory for our device state and initialize it */
        cs = gigaset_initcs(driver, BAS_CHANNELS, 0, 0, cidmode,
                            GIGASET_MODULENAME);
        if (!cs)
                return -ENODEV;
        ucs = cs->hw.bas;

        /* save off device structure ptrs for later use */
        usb_get_dev(udev);
        ucs->udev = udev;
        ucs->interface = interface;
        cs->dev = &interface->dev;

        /* allocate URBs:
         * - one for the interrupt pipe
         * - three for the different uses of the default control pipe
         * - three for each isochronous pipe
         */
        if (!(ucs->urb_int_in = usb_alloc_urb(0, GFP_KERNEL)) ||
            !(ucs->urb_cmd_in = usb_alloc_urb(0, GFP_KERNEL)) ||
            !(ucs->urb_cmd_out = usb_alloc_urb(0, GFP_KERNEL)) ||
            !(ucs->urb_ctrl = usb_alloc_urb(0, GFP_KERNEL)))
                goto allocerr;

        for (j = 0; j < BAS_CHANNELS; ++j) {
                ubc = cs->bcs[j].hw.bas;
                for (i = 0; i < BAS_OUTURBS; ++i)
                        if (!(ubc->isoouturbs[i].urb =
                              usb_alloc_urb(BAS_NUMFRAMES, GFP_KERNEL)))
                                goto allocerr;
                for (i = 0; i < BAS_INURBS; ++i)
                        if (!(ubc->isoinurbs[i] =
                              usb_alloc_urb(BAS_NUMFRAMES, GFP_KERNEL)))
                                goto allocerr;
        }

        ucs->rcvbuf = NULL;
        ucs->rcvbuf_size = 0;

        /* Fill the interrupt urb and send it to the core */
        endpoint = &hostif->endpoint[0].desc;
        usb_fill_int_urb(ucs->urb_int_in, udev,
                         usb_rcvintpipe(udev,
                                        usb_endpoint_num(endpoint)),
                         ucs->int_in_buf, IP_MSGSIZE, read_int_callback, cs,
                         endpoint->bInterval);
        rc = usb_submit_urb(ucs->urb_int_in, GFP_KERNEL);
        if (rc != 0) {
                dev_err(cs->dev, "could not submit interrupt URB: %s\n",
                        get_usb_rcmsg(rc));
                goto error;
        }
        ucs->retry_int_in = 0;

        /* tell the device that the driver is ready */
        rc = req_submit(cs->bcs, HD_DEVICE_INIT_ACK, 0, 0);
        if (rc != 0)
                goto error;

        /* tell common part that the device is ready */
        if (startmode == SM_LOCKED)
                cs->mstate = MS_LOCKED;

        /* save address of controller structure */
        usb_set_intfdata(interface, cs);

        rc = gigaset_start(cs);
        if (rc < 0)
                goto error;

        return 0;

allocerr:
        dev_err(cs->dev, "could not allocate URBs\n");
        rc = -ENOMEM;
error:
        freeurbs(cs);
        usb_set_intfdata(interface, NULL);
        usb_put_dev(udev);
        gigaset_freecs(cs);
        return rc;
}

/* gigaset_disconnect
 * This function is called when the Gigaset base is unplugged.
 */
static void gigaset_disconnect(struct usb_interface *interface)
{
        struct cardstate *cs;
        struct bas_cardstate *ucs;
        int j;

        cs = usb_get_intfdata(interface);

        ucs = cs->hw.bas;

        dev_info(cs->dev, "disconnecting Gigaset base\n");

        /* mark base as not ready, all channels disconnected */
        ucs->basstate = 0;

        /* tell LL all channels are down */
        for (j = 0; j < BAS_CHANNELS; ++j)
                gigaset_bchannel_down(cs->bcs + j);

        /* stop driver (common part) */
        gigaset_stop(cs);

        /* stop delayed work and URBs, free ressources */
        del_timer_sync(&ucs->timer_ctrl);
        del_timer_sync(&ucs->timer_atrdy);
        del_timer_sync(&ucs->timer_cmd_in);
        del_timer_sync(&ucs->timer_int_in);
        cancel_work_sync(&ucs->int_in_wq);
        freeurbs(cs);
        usb_set_intfdata(interface, NULL);
        kfree(ucs->rcvbuf);
        ucs->rcvbuf = NULL;
        ucs->rcvbuf_size = 0;
        usb_put_dev(ucs->udev);
        ucs->interface = NULL;
        ucs->udev = NULL;
        cs->dev = NULL;
        gigaset_freecs(cs);
}

/* gigaset_suspend
 * This function is called before the USB connection is suspended
 * or before the USB device is reset.
 * In the latter case, message == PMSG_ON.
 */
static int gigaset_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct cardstate *cs = usb_get_intfdata(intf);
        struct bas_cardstate *ucs = cs->hw.bas;
        int rc;

        /* set suspend flag; this stops AT command/response traffic */
        if (update_basstate(ucs, BS_SUSPEND, 0) & BS_SUSPEND) {
                gig_dbg(DEBUG_SUSPEND, "already suspended");
                return 0;
        }

        /* wait a bit for blocking conditions to go away */
        rc = wait_event_timeout(ucs->waitqueue,
                                !(ucs->basstate &
                                  (BS_B1OPEN | BS_B2OPEN | BS_ATRDPEND | BS_ATWRPEND)),
                                BAS_TIMEOUT * HZ / 10);
        gig_dbg(DEBUG_SUSPEND, "wait_event_timeout() -> %d", rc);

        /* check for conditions preventing suspend */
        if (ucs->basstate & (BS_B1OPEN | BS_B2OPEN | BS_ATRDPEND | BS_ATWRPEND)) {
                dev_warn(cs->dev, "cannot suspend:\n");
                if (ucs->basstate & BS_B1OPEN)
                        dev_warn(cs->dev, " B channel 1 open\n");
                if (ucs->basstate & BS_B2OPEN)
                        dev_warn(cs->dev, " B channel 2 open\n");
                if (ucs->basstate & BS_ATRDPEND)
                        dev_warn(cs->dev, " receiving AT reply\n");
                if (ucs->basstate & BS_ATWRPEND)
                        dev_warn(cs->dev, " sending AT command\n");
                update_basstate(ucs, 0, BS_SUSPEND);
                return -EBUSY;
        }

        /* close AT channel if open */
        if (ucs->basstate & BS_ATOPEN) {
                gig_dbg(DEBUG_SUSPEND, "closing AT channel");
                rc = req_submit(cs->bcs, HD_CLOSE_ATCHANNEL, 0, 0);
                if (rc) {
                        update_basstate(ucs, 0, BS_SUSPEND);
                        return rc;
                }
                wait_event_timeout(ucs->waitqueue, !ucs->pending,
                                   BAS_TIMEOUT * HZ / 10);
                /* in case of timeout, proceed anyway */
        }

        /* kill all URBs and delayed work that might still be pending */
        usb_kill_urb(ucs->urb_ctrl);
        usb_kill_urb(ucs->urb_int_in);
        del_timer_sync(&ucs->timer_ctrl);
        del_timer_sync(&ucs->timer_atrdy);
        del_timer_sync(&ucs->timer_cmd_in);
        del_timer_sync(&ucs->timer_int_in);

        /* don't try to cancel int_in_wq from within reset as it
         * might be the one requesting the reset
         */
        if (message.event != PM_EVENT_ON)
                cancel_work_sync(&ucs->int_in_wq);

        gig_dbg(DEBUG_SUSPEND, "suspend complete");
        return 0;
}

/* gigaset_resume
 * This function is called after the USB connection has been resumed.
 */
static int gigaset_resume(struct usb_interface *intf)
{
        struct cardstate *cs = usb_get_intfdata(intf);
        struct bas_cardstate *ucs = cs->hw.bas;
        int rc;

        /* resubmit interrupt URB for spontaneous messages from base */
        rc = usb_submit_urb(ucs->urb_int_in, GFP_KERNEL);
        if (rc) {
                dev_err(cs->dev, "could not resubmit interrupt URB: %s\n",
                        get_usb_rcmsg(rc));
                return rc;
        }
        ucs->retry_int_in = 0;

        /* clear suspend flag to reallow activity */
        update_basstate(ucs, 0, BS_SUSPEND);

        gig_dbg(DEBUG_SUSPEND, "resume complete");
        return 0;
}

/* gigaset_pre_reset
 * This function is called before the USB connection is reset.
 */
static int gigaset_pre_reset(struct usb_interface *intf)
{
        /* handle just like suspend */
        return gigaset_suspend(intf, PMSG_ON);
}

/* gigaset_post_reset
 * This function is called after the USB connection has been reset.
 */
static int gigaset_post_reset(struct usb_interface *intf)
{
        /* FIXME: send HD_DEVICE_INIT_ACK? */

        /* resume operations */
        return gigaset_resume(intf);
}


static const struct gigaset_ops gigops = {
        .write_cmd = gigaset_write_cmd,
        .write_room = gigaset_write_room,
        .chars_in_buffer = gigaset_chars_in_buffer,
        .brkchars = gigaset_brkchars,
        .init_bchannel = gigaset_init_bchannel,
        .close_bchannel = gigaset_close_bchannel,
        .initbcshw = gigaset_initbcshw,
        .freebcshw = gigaset_freebcshw,
        .reinitbcshw = gigaset_reinitbcshw,
        .initcshw = gigaset_initcshw,
        .freecshw = gigaset_freecshw,
        .set_modem_ctrl = gigaset_set_modem_ctrl,
        .baud_rate = gigaset_baud_rate,
        .set_line_ctrl = gigaset_set_line_ctrl,
        .send_skb = gigaset_isoc_send_skb,
        .handle_input = gigaset_isoc_input,
};

/* bas_gigaset_init
 * This function is called after the kernel module is loaded.
 */
static int __init bas_gigaset_init(void)
{
        int result;

        /* allocate memory for our driver state and initialize it */
        driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
                                    GIGASET_MODULENAME, GIGASET_DEVNAME,
                                    &gigops, THIS_MODULE);
        if (driver == NULL)
                goto error;

        /* register this driver with the USB subsystem */
        result = usb_register(&gigaset_usb_driver);
        if (result < 0) {
                pr_err("error %d registering USB driver\n", -result);
                goto error;
        }

        pr_info(DRIVER_DESC "\n");
        return 0;

error:
        if (driver)
                gigaset_freedriver(driver);
        driver = NULL;
        return -1;
}

/* bas_gigaset_exit
 * This function is called before the kernel module is unloaded.
 */
static void __exit bas_gigaset_exit(void)
{
        struct bas_cardstate *ucs;
        int i;

        gigaset_blockdriver(driver); /* => probe will fail
                                      * => no gigaset_start any more
                                      */

        /* stop all connected devices */
        for (i = 0; i < driver->minors; i++) {
                if (gigaset_shutdown(driver->cs + i) < 0)
                        continue;               /* no device */
                /* from now on, no isdn callback should be possible */

                /* close all still open channels */
                ucs = driver->cs[i].hw.bas;
                if (ucs->basstate & BS_B1OPEN) {
                        gig_dbg(DEBUG_INIT, "closing B1 channel");
                        usb_control_msg(ucs->udev,
                                        usb_sndctrlpipe(ucs->udev, 0),
                                        HD_CLOSE_B1CHANNEL, OUT_VENDOR_REQ,
                                        0, 0, NULL, 0, BAS_TIMEOUT);
                }
                if (ucs->basstate & BS_B2OPEN) {
                        gig_dbg(DEBUG_INIT, "closing B2 channel");
                        usb_control_msg(ucs->udev,
                                        usb_sndctrlpipe(ucs->udev, 0),
                                        HD_CLOSE_B2CHANNEL, OUT_VENDOR_REQ,
                                        0, 0, NULL, 0, BAS_TIMEOUT);
                }
                if (ucs->basstate & BS_ATOPEN) {
                        gig_dbg(DEBUG_INIT, "closing AT channel");
                        usb_control_msg(ucs->udev,
                                        usb_sndctrlpipe(ucs->udev, 0),
                                        HD_CLOSE_ATCHANNEL, OUT_VENDOR_REQ,
                                        0, 0, NULL, 0, BAS_TIMEOUT);
                }
                ucs->basstate = 0;
        }

        /* deregister this driver with the USB subsystem */
        usb_deregister(&gigaset_usb_driver);
        /* this will call the disconnect-callback */
        /* from now on, no disconnect/probe callback should be running */

        gigaset_freedriver(driver);
        driver = NULL;
}


module_init(bas_gigaset_init);
module_exit(bas_gigaset_exit);

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