/*
   * Stuff used by all variants of the driver
   *
   * Copyright (c) 2001 by Stefan Eilers,
   *                       Hansjoerg Lipp <hjlipp@web.de>,
   *                       Tilman Schmidt <tilman@imap.cc>.
   *
   * =====================================================================
   *	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/isdnif.h>
  #include <linux/export.h>
  
  #define SBUFSIZE	4096	/* sk_buff payload size */
  #define TRANSBUFSIZE	768	/* bytes per skb for transparent receive */
  #define HW_HDR_LEN	2	/* Header size used to store ack info */
  #define MAX_BUF_SIZE	(SBUFSIZE - HW_HDR_LEN)	/* max data packet from LL */
  
  /* == Handling of I4L IO =====================================================*/
  
  /* writebuf_from_LL
   * called by LL to transmit data on an open channel
   * inserts the buffer data into the send queue and starts the transmission
   * Note that this operation must not sleep!
   * When the buffer is processed completely, gigaset_skb_sent() should be called.
   * parameters:
   *	driverID	driver ID as assigned by LL
   *	channel		channel number
   *	ack		if != 0 LL wants to be notified on completion via
   *			statcallb(ISDN_STAT_BSENT)
   *	skb		skb containing data to send
   * return value:
   *	number of accepted bytes
   *	0 if temporarily unable to accept data (out of buffer space)
   *	<0 on error (eg. -EINVAL)
   */
  static int writebuf_from_LL(int driverID, int channel, int ack,
  			    struct sk_buff *skb)
  {
  	struct cardstate *cs = gigaset_get_cs_by_id(driverID);
  	struct bc_state *bcs;
  	unsigned char *ack_header;
  	unsigned len;
  
  	if (!cs) {
  		pr_err("%s: invalid driver ID (%d)
  ", __func__, driverID);
  		return -ENODEV;
  	}
  	if (channel < 0 || channel >= cs->channels) {
  		dev_err(cs->dev, "%s: invalid channel ID (%d)
  ",
  			__func__, channel);
  		return -ENODEV;
  	}
  	bcs = &cs->bcs[channel];
  
  	/* can only handle linear sk_buffs */
  	if (skb_linearize(skb) < 0) {
  		dev_err(cs->dev, "%s: skb_linearize failed
  ", __func__);
  		return -ENOMEM;
  	}
  	len = skb->len;
  
  	gig_dbg(DEBUG_LLDATA,
  		"Receiving data from LL (id: %d, ch: %d, ack: %d, sz: %d)",
  		driverID, channel, ack, len);
  
  	if (!len) {
  		if (ack)
  			dev_notice(cs->dev, "%s: not ACKing empty packet
  ",
  				   __func__);
  		return 0;
  	}
  	if (len > MAX_BUF_SIZE) {
  		dev_err(cs->dev, "%s: packet too large (%d bytes)
  ",
  			__func__, len);
  		return -EINVAL;
  	}
  
  	/* set up acknowledgement header */
  	if (skb_headroom(skb) < HW_HDR_LEN) {
  		/* should never happen */
  		dev_err(cs->dev, "%s: insufficient skb headroom
  ", __func__);
  		return -ENOMEM;
  	}
  	skb_set_mac_header(skb, -HW_HDR_LEN);
  	skb->mac_len = HW_HDR_LEN;
  	ack_header = skb_mac_header(skb);
  	if (ack) {
  		ack_header[0] = len & 0xff;
  		ack_header[1] = len >> 8;
  	} else {
  		ack_header[0] = ack_header[1] = 0;
  	}
  	gig_dbg(DEBUG_MCMD, "skb: len=%u, ack=%d: %02x %02x",
  		len, ack, ack_header[0], ack_header[1]);
  
  	/* pass to device-specific module */
  	return cs->ops->send_skb(bcs, skb);
  }
  
  /**
   * gigaset_skb_sent() - acknowledge sending an skb
   * @bcs:	B channel descriptor structure.
   * @skb:	sent data.
   *
   * Called by hardware module {bas,ser,usb}_gigaset when the data in a
   * skb has been successfully sent, for signalling completion to the LL.
   */
  void gigaset_skb_sent(struct bc_state *bcs, struct sk_buff *skb)
  {
  	isdn_if *iif = bcs->cs->iif;
  	unsigned char *ack_header = skb_mac_header(skb);
  	unsigned len;
  	isdn_ctrl response;
  
  	++bcs->trans_up;
  
  	if (skb->len)
  		dev_warn(bcs->cs->dev, "%s: skb->len==%d
  ",
  			 __func__, skb->len);
  
  	len = ack_header[0] + ((unsigned) ack_header[1] << 8);
  	if (len) {
  		gig_dbg(DEBUG_MCMD, "ACKing to LL (id: %d, ch: %d, sz: %u)",
  			bcs->cs->myid, bcs->channel, len);
  
  		response.driver = bcs->cs->myid;
  		response.command = ISDN_STAT_BSENT;
  		response.arg = bcs->channel;
  		response.parm.length = len;
  		iif->statcallb(&response);
  	}
  }
  EXPORT_SYMBOL_GPL(gigaset_skb_sent);
  
  /**
   * gigaset_skb_rcvd() - pass received skb to LL
   * @bcs:	B channel descriptor structure.
   * @skb:	received data.
   *
   * Called by hardware module {bas,ser,usb}_gigaset when user data has
   * been successfully received, for passing to the LL.
   * Warning: skb must not be accessed anymore!
   */
  void gigaset_skb_rcvd(struct bc_state *bcs, struct sk_buff *skb)
  {
  	isdn_if *iif = bcs->cs->iif;
  
  	iif->rcvcallb_skb(bcs->cs->myid, bcs->channel, skb);
  	bcs->trans_down++;
  }
  EXPORT_SYMBOL_GPL(gigaset_skb_rcvd);
  
  /**
   * gigaset_isdn_rcv_err() - signal receive error
   * @bcs:	B channel descriptor structure.
   *
   * Called by hardware module {bas,ser,usb}_gigaset when a receive error
   * has occurred, for signalling to the LL.
   */
  void gigaset_isdn_rcv_err(struct bc_state *bcs)
  {
  	isdn_if *iif = bcs->cs->iif;
  	isdn_ctrl response;
  
  	/* if currently ignoring packets, just count down */
  	if (bcs->ignore) {
  		bcs->ignore--;
  		return;
  	}
  
  	/* update statistics */
  	bcs->corrupted++;
  
  	/* error -> LL */
  	gig_dbg(DEBUG_CMD, "sending L1ERR");
  	response.driver = bcs->cs->myid;
  	response.command = ISDN_STAT_L1ERR;
  	response.arg = bcs->channel;
  	response.parm.errcode = ISDN_STAT_L1ERR_RECV;
  	iif->statcallb(&response);
  }
  EXPORT_SYMBOL_GPL(gigaset_isdn_rcv_err);
  
  /* This function will be called by LL to send commands
   * NOTE: LL ignores the returned value, for commands other than ISDN_CMD_IOCTL,
   * so don't put too much effort into it.
   */
  static int command_from_LL(isdn_ctrl *cntrl)
  {
  	struct cardstate *cs;
  	struct bc_state *bcs;
  	int retval = 0;
  	char **commands;
  	int ch;
  	int i;
  	size_t l;
  
  	gig_dbg(DEBUG_CMD, "driver: %d, command: %d, arg: 0x%lx",
  		cntrl->driver, cntrl->command, cntrl->arg);
  
  	cs = gigaset_get_cs_by_id(cntrl->driver);
  	if (cs == NULL) {
  		pr_err("%s: invalid driver ID (%d)
  ", __func__, cntrl->driver);
  		return -ENODEV;
  	}
  	ch = cntrl->arg & 0xff;
  
  	switch (cntrl->command) {
  	case ISDN_CMD_IOCTL:
  		dev_warn(cs->dev, "ISDN_CMD_IOCTL not supported
  ");
  		return -EINVAL;
  
  	case ISDN_CMD_DIAL:
  		gig_dbg(DEBUG_CMD,
  			"ISDN_CMD_DIAL (phone: %s, msn: %s, si1: %d, si2: %d)",
  			cntrl->parm.setup.phone, cntrl->parm.setup.eazmsn,
  			cntrl->parm.setup.si1, cntrl->parm.setup.si2);
  
  		if (ch >= cs->channels) {
  			dev_err(cs->dev,
  				"ISDN_CMD_DIAL: invalid channel (%d)
  ", ch);
  			return -EINVAL;
  		}
  		bcs = cs->bcs + ch;
  		if (gigaset_get_channel(bcs) < 0) {
  			dev_err(cs->dev, "ISDN_CMD_DIAL: channel not free
  ");
  			return -EBUSY;
  		}
  		switch (bcs->proto2) {
  		case L2_HDLC:
  			bcs->rx_bufsize = SBUFSIZE;
  			break;
  		default:			/* assume transparent */
  			bcs->rx_bufsize = TRANSBUFSIZE;
  		}
  		dev_kfree_skb(bcs->rx_skb);
  		gigaset_new_rx_skb(bcs);
  
  		commands = kzalloc(AT_NUM * (sizeof *commands), GFP_ATOMIC);
  		if (!commands) {
  			gigaset_free_channel(bcs);
  			dev_err(cs->dev, "ISDN_CMD_DIAL: out of memory
  ");
  			return -ENOMEM;
  		}
  
  		l = 3 + strlen(cntrl->parm.setup.phone);
  		commands[AT_DIAL] = kmalloc(l, GFP_ATOMIC);
  		if (!commands[AT_DIAL])
  			goto oom;
  		if (cntrl->parm.setup.phone[0] == '*' &&
  		    cntrl->parm.setup.phone[1] == '*') {
  			/* internal call: translate ** prefix to CTP value */
  			commands[AT_TYPE] = kstrdup("^SCTP=0\r", GFP_ATOMIC);
  			if (!commands[AT_TYPE])
  				goto oom;
  			snprintf(commands[AT_DIAL], l,
  				 "D%s\r", cntrl->parm.setup.phone + 2);
  		} else {
  			commands[AT_TYPE] = kstrdup("^SCTP=1\r", GFP_ATOMIC);
  			if (!commands[AT_TYPE])
  				goto oom;
  			snprintf(commands[AT_DIAL], l,
  				 "D%s\r", cntrl->parm.setup.phone);
  		}
  
  		l = strlen(cntrl->parm.setup.eazmsn);
  		if (l) {
  			l += 8;
  			commands[AT_MSN] = kmalloc(l, GFP_ATOMIC);
  			if (!commands[AT_MSN])
  				goto oom;
  			snprintf(commands[AT_MSN], l, "^SMSN=%s\r",
  				 cntrl->parm.setup.eazmsn);
  		}
  
  		switch (cntrl->parm.setup.si1) {
  		case 1:		/* audio */
  			/* BC = 9090A3: 3.1 kHz audio, A-law */
  			commands[AT_BC] = kstrdup("^SBC=9090A3\r", GFP_ATOMIC);
  			if (!commands[AT_BC])
  				goto oom;
  			break;
  		case 7:		/* data */
  		default:	/* hope the app knows what it is doing */
  			/* BC = 8890: unrestricted digital information */
  			commands[AT_BC] = kstrdup("^SBC=8890\r", GFP_ATOMIC);
  			if (!commands[AT_BC])
  				goto oom;
  		}
  		/* ToDo: other si1 values, inspect si2, set HLC/LLC */
  
  		commands[AT_PROTO] = kmalloc(9, GFP_ATOMIC);
  		if (!commands[AT_PROTO])
  			goto oom;
  		snprintf(commands[AT_PROTO], 9, "^SBPR=%u\r", bcs->proto2);
  
  		commands[AT_ISO] = kmalloc(9, GFP_ATOMIC);
  		if (!commands[AT_ISO])
  			goto oom;
  		snprintf(commands[AT_ISO], 9, "^SISO=%u\r",
  			 (unsigned) bcs->channel + 1);
  
  		if (!gigaset_add_event(cs, &bcs->at_state, EV_DIAL, commands,
  				       bcs->at_state.seq_index, NULL)) {
  			for (i = 0; i < AT_NUM; ++i)
  				kfree(commands[i]);
  			kfree(commands);
  			gigaset_free_channel(bcs);
  			return -ENOMEM;
  		}
  		gigaset_schedule_event(cs);
  		break;
  	case ISDN_CMD_ACCEPTD:
  		gig_dbg(DEBUG_CMD, "ISDN_CMD_ACCEPTD");
  		if (ch >= cs->channels) {
  			dev_err(cs->dev,
  				"ISDN_CMD_ACCEPTD: invalid channel (%d)
  ", ch);
  			return -EINVAL;
  		}
  		bcs = cs->bcs + ch;
  		switch (bcs->proto2) {
  		case L2_HDLC:
  			bcs->rx_bufsize = SBUFSIZE;
  			break;
  		default:			/* assume transparent */
  			bcs->rx_bufsize = TRANSBUFSIZE;
  		}
  		dev_kfree_skb(bcs->rx_skb);
  		gigaset_new_rx_skb(bcs);
  		if (!gigaset_add_event(cs, &bcs->at_state,
  				       EV_ACCEPT, NULL, 0, NULL))
  			return -ENOMEM;
  		gigaset_schedule_event(cs);
  
  		break;
  	case ISDN_CMD_HANGUP:
  		gig_dbg(DEBUG_CMD, "ISDN_CMD_HANGUP");
  		if (ch >= cs->channels) {
  			dev_err(cs->dev,
  				"ISDN_CMD_HANGUP: invalid channel (%d)
  ", ch);
  			return -EINVAL;
  		}
  		bcs = cs->bcs + ch;
  		if (!gigaset_add_event(cs, &bcs->at_state,
  				       EV_HUP, NULL, 0, NULL))
  			return -ENOMEM;
  		gigaset_schedule_event(cs);
  
  		break;
  	case ISDN_CMD_CLREAZ: /* Do not signal incoming signals */
  		dev_info(cs->dev, "ignoring ISDN_CMD_CLREAZ
  ");
  		break;
  	case ISDN_CMD_SETEAZ: /* Signal incoming calls for given MSN */
  		dev_info(cs->dev, "ignoring ISDN_CMD_SETEAZ (%s)
  ",
  			 cntrl->parm.num);
  		break;
  	case ISDN_CMD_SETL2: /* Set L2 to given protocol */
  		if (ch >= cs->channels) {
  			dev_err(cs->dev,
  				"ISDN_CMD_SETL2: invalid channel (%d)
  ", ch);
  			return -EINVAL;
  		}
  		bcs = cs->bcs + ch;
  		if (bcs->chstate & CHS_D_UP) {
  			dev_err(cs->dev,
  				"ISDN_CMD_SETL2: channel active (%d)
  ", ch);
  			return -EINVAL;
  		}
  		switch (cntrl->arg >> 8) {
  		case ISDN_PROTO_L2_HDLC:
  			gig_dbg(DEBUG_CMD, "ISDN_CMD_SETL2: setting L2_HDLC");
  			bcs->proto2 = L2_HDLC;
  			break;
  		case ISDN_PROTO_L2_TRANS:
  			gig_dbg(DEBUG_CMD, "ISDN_CMD_SETL2: setting L2_VOICE");
  			bcs->proto2 = L2_VOICE;
  			break;
  		default:
  			dev_err(cs->dev,
  				"ISDN_CMD_SETL2: unsupported protocol (%lu)
  ",
  				cntrl->arg >> 8);
  			return -EINVAL;
  		}
  		break;
  	case ISDN_CMD_SETL3: /* Set L3 to given protocol */
  		gig_dbg(DEBUG_CMD, "ISDN_CMD_SETL3");
  		if (ch >= cs->channels) {
  			dev_err(cs->dev,
  				"ISDN_CMD_SETL3: invalid channel (%d)
  ", ch);
  			return -EINVAL;
  		}
  
  		if (cntrl->arg >> 8 != ISDN_PROTO_L3_TRANS) {
  			dev_err(cs->dev,
  				"ISDN_CMD_SETL3: unsupported protocol (%lu)
  ",
  				cntrl->arg >> 8);
  			return -EINVAL;
  		}
  
  		break;
  
  	default:
  		gig_dbg(DEBUG_CMD, "unknown command %d from LL",
  			cntrl->command);
  		return -EINVAL;
  	}
  
  	return retval;
  
  oom:
  	dev_err(bcs->cs->dev, "out of memory
  ");
  	for (i = 0; i < AT_NUM; ++i)
  		kfree(commands[i]);
  	kfree(commands);
  	gigaset_free_channel(bcs);
  	return -ENOMEM;
  }
  
  static void gigaset_i4l_cmd(struct cardstate *cs, int cmd)
  {
  	isdn_if *iif = cs->iif;
  	isdn_ctrl command;
  
  	command.driver = cs->myid;
  	command.command = cmd;
  	command.arg = 0;
  	iif->statcallb(&command);
  }
  
  static void gigaset_i4l_channel_cmd(struct bc_state *bcs, int cmd)
  {
  	isdn_if *iif = bcs->cs->iif;
  	isdn_ctrl command;
  
  	command.driver = bcs->cs->myid;
  	command.command = cmd;
  	command.arg = bcs->channel;
  	iif->statcallb(&command);
  }
  
  /**
   * gigaset_isdn_icall() - signal incoming call
   * @at_state:	connection state structure.
   *
   * Called by main module to notify the LL that an incoming call has been
   * received. @at_state contains the parameters of the call.
   *
   * Return value: call disposition (ICALL_*)
   */
  int gigaset_isdn_icall(struct at_state_t *at_state)
  {
  	struct cardstate *cs = at_state->cs;
  	struct bc_state *bcs = at_state->bcs;
  	isdn_if *iif = cs->iif;
  	isdn_ctrl response;
  	int retval;
  
  	/* fill ICALL structure */
  	response.parm.setup.si1 = 0;	/* default: unknown */
  	response.parm.setup.si2 = 0;
  	response.parm.setup.screen = 0;
  	response.parm.setup.plan = 0;
  	if (!at_state->str_var[STR_ZBC]) {
  		/* no BC (internal call): assume speech, A-law */
  		response.parm.setup.si1 = 1;
  	} else if (!strcmp(at_state->str_var[STR_ZBC], "8890")) {
  		/* unrestricted digital information */
  		response.parm.setup.si1 = 7;
  	} else if (!strcmp(at_state->str_var[STR_ZBC], "8090A3")) {
  		/* speech, A-law */
  		response.parm.setup.si1 = 1;
  	} else if (!strcmp(at_state->str_var[STR_ZBC], "9090A3")) {
  		/* 3,1 kHz audio, A-law */
  		response.parm.setup.si1 = 1;
  		response.parm.setup.si2 = 2;
  	} else {
  		dev_warn(cs->dev, "RING ignored - unsupported BC %s
  ",
  			 at_state->str_var[STR_ZBC]);
  		return ICALL_IGNORE;
  	}
  	if (at_state->str_var[STR_NMBR]) {
  		strlcpy(response.parm.setup.phone, at_state->str_var[STR_NMBR],
  			sizeof response.parm.setup.phone);
  	} else
  		response.parm.setup.phone[0] = 0;
  	if (at_state->str_var[STR_ZCPN]) {
  		strlcpy(response.parm.setup.eazmsn, at_state->str_var[STR_ZCPN],
  			sizeof response.parm.setup.eazmsn);
  	} else
  		response.parm.setup.eazmsn[0] = 0;
  
  	if (!bcs) {
  		dev_notice(cs->dev, "no channel for incoming call
  ");
  		response.command = ISDN_STAT_ICALLW;
  		response.arg = 0;
  	} else {
  		gig_dbg(DEBUG_CMD, "Sending ICALL");
  		response.command = ISDN_STAT_ICALL;
  		response.arg = bcs->channel;
  	}
  	response.driver = cs->myid;
  	retval = iif->statcallb(&response);
  	gig_dbg(DEBUG_CMD, "Response: %d", retval);
  	switch (retval) {
  	case 0:	/* no takers */
  		return ICALL_IGNORE;
  	case 1:	/* alerting */
  		bcs->chstate |= CHS_NOTIFY_LL;
  		return ICALL_ACCEPT;
  	case 2:	/* reject */
  		return ICALL_REJECT;
  	case 3:	/* incomplete */
  		dev_warn(cs->dev,
  			 "LL requested unsupported feature: Incomplete Number
  ");
  		return ICALL_IGNORE;
  	case 4:	/* proceeding */
  		/* Gigaset will send ALERTING anyway.
  		 * There doesn't seem to be a way to avoid this.
  		 */
  		return ICALL_ACCEPT;
  	case 5:	/* deflect */
  		dev_warn(cs->dev,
  			 "LL requested unsupported feature: Call Deflection
  ");
  		return ICALL_IGNORE;
  	default:
  		dev_err(cs->dev, "LL error %d on ICALL
  ", retval);
  		return ICALL_IGNORE;
  	}
  }
  
  /**
   * gigaset_isdn_connD() - signal D channel connect
   * @bcs:	B channel descriptor structure.
   *
   * Called by main module to notify the LL that the D channel connection has
   * been established.
   */
  void gigaset_isdn_connD(struct bc_state *bcs)
  {
  	gig_dbg(DEBUG_CMD, "sending DCONN");
  	gigaset_i4l_channel_cmd(bcs, ISDN_STAT_DCONN);
  }
  
  /**
   * gigaset_isdn_hupD() - signal D channel hangup
   * @bcs:	B channel descriptor structure.
   *
   * Called by main module to notify the LL that the D channel connection has
   * been shut down.
   */
  void gigaset_isdn_hupD(struct bc_state *bcs)
  {
  	gig_dbg(DEBUG_CMD, "sending DHUP");
  	gigaset_i4l_channel_cmd(bcs, ISDN_STAT_DHUP);
  }
  
  /**
   * gigaset_isdn_connB() - signal B channel connect
   * @bcs:	B channel descriptor structure.
   *
   * Called by main module to notify the LL that the B channel connection has
   * been established.
   */
  void gigaset_isdn_connB(struct bc_state *bcs)
  {
  	gig_dbg(DEBUG_CMD, "sending BCONN");
  	gigaset_i4l_channel_cmd(bcs, ISDN_STAT_BCONN);
  }
  
  /**
   * gigaset_isdn_hupB() - signal B channel hangup
   * @bcs:	B channel descriptor structure.
   *
   * Called by main module to notify the LL that the B channel connection has
   * been shut down.
   */
  void gigaset_isdn_hupB(struct bc_state *bcs)
  {
  	gig_dbg(DEBUG_CMD, "sending BHUP");
  	gigaset_i4l_channel_cmd(bcs, ISDN_STAT_BHUP);
  }
  
  /**
   * gigaset_isdn_start() - signal device availability
   * @cs:		device descriptor structure.
   *
   * Called by main module to notify the LL that the device is available for
   * use.
   */
  void gigaset_isdn_start(struct cardstate *cs)
  {
  	gig_dbg(DEBUG_CMD, "sending RUN");
  	gigaset_i4l_cmd(cs, ISDN_STAT_RUN);
  }
  
  /**
   * gigaset_isdn_stop() - signal device unavailability
   * @cs:		device descriptor structure.
   *
   * Called by main module to notify the LL that the device is no longer
   * available for use.
   */
  void gigaset_isdn_stop(struct cardstate *cs)
  {
  	gig_dbg(DEBUG_CMD, "sending STOP");
  	gigaset_i4l_cmd(cs, ISDN_STAT_STOP);
  }
  
  /**
   * gigaset_isdn_regdev() - register to LL
   * @cs:		device descriptor structure.
   * @isdnid:	device name.
   *
   * Return value: 0 on success, error code < 0 on failure
   */
  int gigaset_isdn_regdev(struct cardstate *cs, const char *isdnid)
  {
  	isdn_if *iif;
  
  	iif = kmalloc(sizeof *iif, GFP_KERNEL);
  	if (!iif) {
  		pr_err("out of memory
  ");
  		return -ENOMEM;
  	}
  
  	if (snprintf(iif->id, sizeof iif->id, "%s_%u", isdnid, cs->minor_index)
  	    >= sizeof iif->id) {
  		pr_err("ID too long: %s
  ", isdnid);
  		kfree(iif);
  		return -EINVAL;
  	}
  
  	iif->owner = THIS_MODULE;
  	iif->channels = cs->channels;
  	iif->maxbufsize = MAX_BUF_SIZE;
  	iif->features = ISDN_FEATURE_L2_TRANS |
  		ISDN_FEATURE_L2_HDLC |
  		ISDN_FEATURE_L2_X75I |
  		ISDN_FEATURE_L3_TRANS |
  		ISDN_FEATURE_P_EURO;
  	iif->hl_hdrlen = HW_HDR_LEN;		/* Area for storing ack */
  	iif->command = command_from_LL;
  	iif->writebuf_skb = writebuf_from_LL;
  	iif->writecmd = NULL;			/* Don't support isdnctrl */
  	iif->readstat = NULL;			/* Don't support isdnctrl */
  	iif->rcvcallb_skb = NULL;		/* Will be set by LL */
  	iif->statcallb = NULL;			/* Will be set by LL */
  
  	if (!register_isdn(iif)) {
  		pr_err("register_isdn failed
  ");
  		kfree(iif);
  		return -EINVAL;
  	}
  
  	cs->iif = iif;
  	cs->myid = iif->channels;		/* Set my device id */
  	cs->hw_hdr_len = HW_HDR_LEN;
  	return 0;
  }
  
  /**
   * gigaset_isdn_unregdev() - unregister device from LL
   * @cs:		device descriptor structure.
   */
  void gigaset_isdn_unregdev(struct cardstate *cs)
  {
  	gig_dbg(DEBUG_CMD, "sending UNLOAD");
  	gigaset_i4l_cmd(cs, ISDN_STAT_UNLOAD);
  	kfree(cs->iif);
  	cs->iif = NULL;
  }
  
  /**
   * gigaset_isdn_regdrv() - register driver to LL
   */
  void gigaset_isdn_regdrv(void)
  {
  	pr_info("ISDN4Linux interface
  ");
  	/* nothing to do */
  }
  
  /**
   * gigaset_isdn_unregdrv() - unregister driver from LL
   */
  void gigaset_isdn_unregdrv(void)
  {
  	/* nothing to do */
  }