// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   *
   *  Bluetooth HCI UART driver
   *
   *  Copyright (C) 2002-2003  Fabrizio Gennari <fabrizio.gennari@philips.com>
   *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>

   */

  #include <linux/module.h>
  
  #include <linux/kernel.h>
  #include <linux/init.h>

  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/interrupt.h>
  #include <linux/ptrace.h>
  #include <linux/poll.h>
  
  #include <linux/slab.h>
  #include <linux/tty.h>
  #include <linux/errno.h>
  #include <linux/string.h>
  #include <linux/signal.h>
  #include <linux/ioctl.h>
  #include <linux/skbuff.h>

  #include <linux/bitrev.h>
  #include <asm/unaligned.h>

  
  #include <net/bluetooth/bluetooth.h>
  #include <net/bluetooth/hci_core.h>

  #include "hci_uart.h"

  static bool txcrc = true;
  static bool hciextn = true;

  #define BCSP_TXWINSIZE	4
  
  #define BCSP_ACK_PKT	0x05
  #define BCSP_LE_PKT	0x06
  
  struct bcsp_struct {
  	struct sk_buff_head unack;	/* Unack'ed packets queue */
  	struct sk_buff_head rel;	/* Reliable packets queue */
  	struct sk_buff_head unrel;	/* Unreliable packets queue */
  
  	unsigned long rx_count;
  	struct	sk_buff *rx_skb;
  	u8	rxseq_txack;		/* rxseq == txack. */
  	u8	rxack;			/* Last packet sent by us that the peer ack'ed */
  	struct	timer_list tbcsp;

  	struct	hci_uart *hu;

  
  	enum {
  		BCSP_W4_PKT_DELIMITER,
  		BCSP_W4_PKT_START,
  		BCSP_W4_BCSP_HDR,
  		BCSP_W4_DATA,
  		BCSP_W4_CRC
  	} rx_state;
  
  	enum {
  		BCSP_ESCSTATE_NOESC,
  		BCSP_ESCSTATE_ESC
  	} rx_esc_state;
  
  	u8	use_crc;
  	u16	message_crc;
  	u8	txack_req;		/* Do we need to send ack's to the peer? */
  
  	/* Reliable packet sequence number - used to assign seq to each rel pkt. */
  	u8	msgq_txseq;
  };

  /* ---- BCSP CRC calculation ---- */
  
  /* Table for calculating CRC for polynomial 0x1021, LSB processed first,

   * initial value 0xffff, bits shifted in reverse order.
   */

  
  static const u16 crc_table[] = {
  	0x0000, 0x1081, 0x2102, 0x3183,
  	0x4204, 0x5285, 0x6306, 0x7387,
  	0x8408, 0x9489, 0xa50a, 0xb58b,
  	0xc60c, 0xd68d, 0xe70e, 0xf78f
  };
  
  /* Initialise the crc calculator */
  #define BCSP_CRC_INIT(x) x = 0xffff

  /* Update crc with next data byte
   *
   * Implementation note
   *     The data byte is treated as two nibbles.  The crc is generated
   *     in reverse, i.e., bits are fed into the register from the top.
   */

  static void bcsp_crc_update(u16 *crc, u8 d)
  {
  	u16 reg = *crc;
  
  	reg = (reg >> 4) ^ crc_table[(reg ^ d) & 0x000f];
  	reg = (reg >> 4) ^ crc_table[(reg ^ (d >> 4)) & 0x000f];
  
  	*crc = reg;
  }

  /* ---- BCSP core ---- */
  
  static void bcsp_slip_msgdelim(struct sk_buff *skb)
  {
  	const char pkt_delim = 0xc0;

  	skb_put_data(skb, &pkt_delim, 1);

  }
  
  static void bcsp_slip_one_byte(struct sk_buff *skb, u8 c)
  {
  	const char esc_c0[2] = { 0xdb, 0xdc };
  	const char esc_db[2] = { 0xdb, 0xdd };
  
  	switch (c) {
  	case 0xc0:

  		skb_put_data(skb, &esc_c0, 2);

  		break;
  	case 0xdb:

  		skb_put_data(skb, &esc_db, 2);

  		break;
  	default:

  		skb_put_data(skb, &c, 1);

  	}
  }
  
  static int bcsp_enqueue(struct hci_uart *hu, struct sk_buff *skb)
  {
  	struct bcsp_struct *bcsp = hu->priv;
  
  	if (skb->len > 0xFFF) {
  		BT_ERR("Packet too long");
  		kfree_skb(skb);
  		return 0;
  	}

  	switch (hci_skb_pkt_type(skb)) {

  	case HCI_ACLDATA_PKT:
  	case HCI_COMMAND_PKT:
  		skb_queue_tail(&bcsp->rel, skb);
  		break;
  
  	case HCI_SCODATA_PKT:
  		skb_queue_tail(&bcsp->unrel, skb);
  		break;
  
  	default:
  		BT_ERR("Unknown packet type");
  		kfree_skb(skb);
  		break;
  	}
  
  	return 0;
  }
  
  static struct sk_buff *bcsp_prepare_pkt(struct bcsp_struct *bcsp, u8 *data,

  					int len, int pkt_type)

  {
  	struct sk_buff *nskb;
  	u8 hdr[4], chan;

  	u16 BCSP_CRC_INIT(bcsp_txmsg_crc);

  	int rel, i;

  
  	switch (pkt_type) {
  	case HCI_ACLDATA_PKT:
  		chan = 6;	/* BCSP ACL channel */
  		rel = 1;	/* reliable channel */
  		break;
  	case HCI_COMMAND_PKT:
  		chan = 5;	/* BCSP cmd/evt channel */
  		rel = 1;	/* reliable channel */
  		break;
  	case HCI_SCODATA_PKT:
  		chan = 7;	/* BCSP SCO channel */
  		rel = 0;	/* unreliable channel */
  		break;
  	case BCSP_LE_PKT:
  		chan = 1;	/* BCSP LE channel */
  		rel = 0;	/* unreliable channel */
  		break;
  	case BCSP_ACK_PKT:
  		chan = 0;	/* BCSP internal channel */
  		rel = 0;	/* unreliable channel */
  		break;
  	default:
  		BT_ERR("Unknown packet type");
  		return NULL;
  	}
  
  	if (hciextn && chan == 5) {

  		__le16 opcode = ((struct hci_command_hdr *)data)->opcode;

  		/* Vendor specific commands */

  		if (hci_opcode_ogf(__le16_to_cpu(opcode)) == 0x3f) {

  			u8 desc = *(data + HCI_COMMAND_HDR_SIZE);

  			if ((desc & 0xf0) == 0xc0) {
  				data += HCI_COMMAND_HDR_SIZE + 1;
  				len  -= HCI_COMMAND_HDR_SIZE + 1;
  				chan = desc & 0x0f;
  			}
  		}
  	}
  
  	/* Max len of packet: (original len +4(bcsp hdr) +2(crc))*2

  	 * (because bytes 0xc0 and 0xdb are escaped, worst case is
  	 * when the packet is all made of 0xc0 and 0xdb :) )
  	 * + 2 (0xc0 delimiters at start and end).
  	 */

  
  	nskb = alloc_skb((len + 6) * 2 + 2, GFP_ATOMIC);
  	if (!nskb)
  		return NULL;

  	hci_skb_pkt_type(nskb) = pkt_type;

  
  	bcsp_slip_msgdelim(nskb);
  
  	hdr[0] = bcsp->rxseq_txack << 3;
  	bcsp->txack_req = 0;
  	BT_DBG("We request packet no %u to card", bcsp->rxseq_txack);
  
  	if (rel) {
  		hdr[0] |= 0x80 + bcsp->msgq_txseq;
  		BT_DBG("Sending packet with seqno %u", bcsp->msgq_txseq);

  		bcsp->msgq_txseq = (bcsp->msgq_txseq + 1) & 0x07;

  	}

  
  	if (bcsp->use_crc)
  		hdr[0] |= 0x40;

  
  	hdr[1] = ((len << 4) & 0xff) | chan;
  	hdr[2] = len >> 4;
  	hdr[3] = ~(hdr[0] + hdr[1] + hdr[2]);
  
  	/* Put BCSP header */
  	for (i = 0; i < 4; i++) {
  		bcsp_slip_one_byte(nskb, hdr[i]);

  
  		if (bcsp->use_crc)
  			bcsp_crc_update(&bcsp_txmsg_crc, hdr[i]);

  	}
  
  	/* Put payload */
  	for (i = 0; i < len; i++) {
  		bcsp_slip_one_byte(nskb, data[i]);

  
  		if (bcsp->use_crc)
  			bcsp_crc_update(&bcsp_txmsg_crc, data[i]);

  	}

  	/* Put CRC */

  	if (bcsp->use_crc) {

  		bcsp_txmsg_crc = bitrev16(bcsp_txmsg_crc);

  		bcsp_slip_one_byte(nskb, (u8)((bcsp_txmsg_crc >> 8) & 0x00ff));
  		bcsp_slip_one_byte(nskb, (u8)(bcsp_txmsg_crc & 0x00ff));

  	}

  
  	bcsp_slip_msgdelim(nskb);
  	return nskb;
  }
  
  /* This is a rewrite of pkt_avail in ABCSP */
  static struct sk_buff *bcsp_dequeue(struct hci_uart *hu)
  {
  	struct bcsp_struct *bcsp = hu->priv;
  	unsigned long flags;
  	struct sk_buff *skb;

  	/* First of all, check for unreliable messages in the queue,

  	 * since they have priority
  	 */

  	skb = skb_dequeue(&bcsp->unrel);
  	if (skb != NULL) {

  		struct sk_buff *nskb;
  
  		nskb = bcsp_prepare_pkt(bcsp, skb->data, skb->len,
  					hci_skb_pkt_type(skb));

  		if (nskb) {
  			kfree_skb(skb);
  			return nskb;
  		} else {
  			skb_queue_head(&bcsp->unrel, skb);
  			BT_ERR("Could not dequeue pkt because alloc_skb failed");
  		}
  	}
  
  	/* Now, try to send a reliable pkt. We can only send a

  	 * reliable packet if the number of packets sent but not yet ack'ed
  	 * is < than the winsize
  	 */

  	spin_lock_irqsave_nested(&bcsp->unack.lock, flags, SINGLE_DEPTH_NESTING);

  	if (bcsp->unack.qlen < BCSP_TXWINSIZE) {
  		skb = skb_dequeue(&bcsp->rel);
  		if (skb != NULL) {

  			struct sk_buff *nskb;
  
  			nskb = bcsp_prepare_pkt(bcsp, skb->data, skb->len,
  						hci_skb_pkt_type(skb));

  			if (nskb) {
  				__skb_queue_tail(&bcsp->unack, skb);
  				mod_timer(&bcsp->tbcsp, jiffies + HZ / 4);
  				spin_unlock_irqrestore(&bcsp->unack.lock, flags);
  				return nskb;
  			} else {
  				skb_queue_head(&bcsp->rel, skb);
  				BT_ERR("Could not dequeue pkt because alloc_skb failed");
  			}

  		}
  	}
  
  	spin_unlock_irqrestore(&bcsp->unack.lock, flags);

  	/* We could not send a reliable packet, either because there are

  	 * none or because there are too many unack'ed pkts. Did we receive
  	 * any packets we have not acknowledged yet ?
  	 */

  
  	if (bcsp->txack_req) {
  		/* if so, craft an empty ACK pkt and send it on BCSP unreliable

  		 * channel 0
  		 */

  		struct sk_buff *nskb = bcsp_prepare_pkt(bcsp, NULL, 0, BCSP_ACK_PKT);
  		return nskb;
  	}
  
  	/* We have nothing to send */
  	return NULL;
  }
  
  static int bcsp_flush(struct hci_uart *hu)
  {
  	BT_DBG("hu %p", hu);
  	return 0;
  }
  
  /* Remove ack'ed packets */
  static void bcsp_pkt_cull(struct bcsp_struct *bcsp)
  {

  	struct sk_buff *skb, *tmp;

  	unsigned long flags;

  	int i, pkts_to_be_removed;
  	u8 seqno;
  
  	spin_lock_irqsave(&bcsp->unack.lock, flags);

  	pkts_to_be_removed = skb_queue_len(&bcsp->unack);

  	seqno = bcsp->msgq_txseq;
  
  	while (pkts_to_be_removed) {
  		if (bcsp->rxack == seqno)
  			break;
  		pkts_to_be_removed--;
  		seqno = (seqno - 1) & 0x07;
  	}
  
  	if (bcsp->rxack != seqno)
  		BT_ERR("Peer acked invalid packet");
  
  	BT_DBG("Removing %u pkts out of %u, up to seqno %u",

  	       pkts_to_be_removed, skb_queue_len(&bcsp->unack),
  	       (seqno - 1) & 0x07);

  	i = 0;
  	skb_queue_walk_safe(&bcsp->unack, skb, tmp) {

  		if (i >= pkts_to_be_removed)

  			break;

  		i++;

  		__skb_unlink(skb, &bcsp->unack);
  		kfree_skb(skb);

  	}

  	if (skb_queue_empty(&bcsp->unack))

  		del_timer(&bcsp->tbcsp);

  	spin_unlock_irqrestore(&bcsp->unack.lock, flags);
  
  	if (i != pkts_to_be_removed)
  		BT_ERR("Removed only %u out of %u pkts", i, pkts_to_be_removed);
  }
  
  /* Handle BCSP link-establishment packets. When we

   * detect a "sync" packet, symptom that the BT module has reset,
   * we do nothing :) (yet)
   */

  static void bcsp_handle_le_pkt(struct hci_uart *hu)
  {
  	struct bcsp_struct *bcsp = hu->priv;
  	u8 conf_pkt[4]     = { 0xad, 0xef, 0xac, 0xed };
  	u8 conf_rsp_pkt[4] = { 0xde, 0xad, 0xd0, 0xd0 };
  	u8 sync_pkt[4]     = { 0xda, 0xdc, 0xed, 0xed };
  
  	/* spot "conf" pkts and reply with a "conf rsp" pkt */
  	if (bcsp->rx_skb->data[1] >> 4 == 4 && bcsp->rx_skb->data[2] == 0 &&

  	    !memcmp(&bcsp->rx_skb->data[4], conf_pkt, 4)) {

  		struct sk_buff *nskb = alloc_skb(4, GFP_ATOMIC);
  
  		BT_DBG("Found a LE conf pkt");
  		if (!nskb)
  			return;

  		skb_put_data(nskb, conf_rsp_pkt, 4);

  		hci_skb_pkt_type(nskb) = BCSP_LE_PKT;

  
  		skb_queue_head(&bcsp->unrel, nskb);
  		hci_uart_tx_wakeup(hu);
  	}
  	/* Spot "sync" pkts. If we find one...disaster! */
  	else if (bcsp->rx_skb->data[1] >> 4 == 4 && bcsp->rx_skb->data[2] == 0 &&

  		 !memcmp(&bcsp->rx_skb->data[4], sync_pkt, 4)) {

  		BT_ERR("Found a LE sync pkt, card has reset");
  	}
  }
  
  static inline void bcsp_unslip_one_byte(struct bcsp_struct *bcsp, unsigned char byte)
  {
  	const u8 c0 = 0xc0, db = 0xdb;
  
  	switch (bcsp->rx_esc_state) {
  	case BCSP_ESCSTATE_NOESC:
  		switch (byte) {
  		case 0xdb:
  			bcsp->rx_esc_state = BCSP_ESCSTATE_ESC;
  			break;
  		default:

  			skb_put_data(bcsp->rx_skb, &byte, 1);

  			if ((bcsp->rx_skb->data[0] & 0x40) != 0 &&

  			    bcsp->rx_state != BCSP_W4_CRC)

  				bcsp_crc_update(&bcsp->message_crc, byte);
  			bcsp->rx_count--;
  		}
  		break;
  
  	case BCSP_ESCSTATE_ESC:
  		switch (byte) {
  		case 0xdc:

  			skb_put_data(bcsp->rx_skb, &c0, 1);

  			if ((bcsp->rx_skb->data[0] & 0x40) != 0 &&

  			    bcsp->rx_state != BCSP_W4_CRC)

  				bcsp_crc_update(&bcsp->message_crc, 0xc0);

  			bcsp->rx_esc_state = BCSP_ESCSTATE_NOESC;
  			bcsp->rx_count--;
  			break;
  
  		case 0xdd:

  			skb_put_data(bcsp->rx_skb, &db, 1);

  			if ((bcsp->rx_skb->data[0] & 0x40) != 0 &&

  			    bcsp->rx_state != BCSP_W4_CRC)

  				bcsp_crc_update(&bcsp->message_crc, 0xdb);

  			bcsp->rx_esc_state = BCSP_ESCSTATE_NOESC;
  			bcsp->rx_count--;
  			break;
  
  		default:

  			BT_ERR("Invalid byte %02x after esc byte", byte);

  			kfree_skb(bcsp->rx_skb);
  			bcsp->rx_skb = NULL;
  			bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
  			bcsp->rx_count = 0;
  		}
  	}
  }

  static void bcsp_complete_rx_pkt(struct hci_uart *hu)

  {
  	struct bcsp_struct *bcsp = hu->priv;

  	int pass_up = 0;

  
  	if (bcsp->rx_skb->data[0] & 0x80) {	/* reliable pkt */
  		BT_DBG("Received seqno %u from card", bcsp->rxseq_txack);

  
  		/* check the rx sequence number is as expected */
  		if ((bcsp->rx_skb->data[0] & 0x07) == bcsp->rxseq_txack) {
  			bcsp->rxseq_txack++;
  			bcsp->rxseq_txack %= 0x8;
  		} else {
  			/* handle re-transmitted packet or
  			 * when packet was missed
  			 */
  			BT_ERR("Out-of-order packet arrived, got %u expected %u",
  			       bcsp->rx_skb->data[0] & 0x07, bcsp->rxseq_txack);
  
  			/* do not process out-of-order packet payload */
  			pass_up = 2;
  		}
  
  		/* send current txack value to all received reliable packets */
  		bcsp->txack_req = 1;

  
  		/* If needed, transmit an ack pkt */
  		hci_uart_tx_wakeup(hu);
  	}
  
  	bcsp->rxack = (bcsp->rx_skb->data[0] >> 3) & 0x07;
  	BT_DBG("Request for pkt %u from card", bcsp->rxack);

  	/* handle received ACK indications,
  	 * including those from out-of-order packets
  	 */

  	bcsp_pkt_cull(bcsp);

  
  	if (pass_up != 2) {
  		if ((bcsp->rx_skb->data[1] & 0x0f) == 6 &&
  		    (bcsp->rx_skb->data[0] & 0x80)) {
  			hci_skb_pkt_type(bcsp->rx_skb) = HCI_ACLDATA_PKT;
  			pass_up = 1;
  		} else if ((bcsp->rx_skb->data[1] & 0x0f) == 5 &&
  			   (bcsp->rx_skb->data[0] & 0x80)) {
  			hci_skb_pkt_type(bcsp->rx_skb) = HCI_EVENT_PKT;
  			pass_up = 1;
  		} else if ((bcsp->rx_skb->data[1] & 0x0f) == 7) {
  			hci_skb_pkt_type(bcsp->rx_skb) = HCI_SCODATA_PKT;
  			pass_up = 1;
  		} else if ((bcsp->rx_skb->data[1] & 0x0f) == 1 &&
  			   !(bcsp->rx_skb->data[0] & 0x80)) {
  			bcsp_handle_le_pkt(hu);
  			pass_up = 0;
  		} else {
  			pass_up = 0;
  		}
  	}
  
  	if (pass_up == 0) {

  		struct hci_event_hdr hdr;
  		u8 desc = (bcsp->rx_skb->data[1] & 0x0f);
  
  		if (desc != 0 && desc != 1) {
  			if (hciextn) {
  				desc |= 0xc0;
  				skb_pull(bcsp->rx_skb, 4);
  				memcpy(skb_push(bcsp->rx_skb, 1), &desc, 1);
  
  				hdr.evt = 0xff;
  				hdr.plen = bcsp->rx_skb->len;
  				memcpy(skb_push(bcsp->rx_skb, HCI_EVENT_HDR_SIZE), &hdr, HCI_EVENT_HDR_SIZE);

  				hci_skb_pkt_type(bcsp->rx_skb) = HCI_EVENT_PKT;

  				hci_recv_frame(hu->hdev, bcsp->rx_skb);

  			} else {

  				BT_ERR("Packet for unknown channel (%u %s)",

  				       bcsp->rx_skb->data[1] & 0x0f,
  				       bcsp->rx_skb->data[0] & 0x80 ?
  				       "reliable" : "unreliable");

  				kfree_skb(bcsp->rx_skb);
  			}
  		} else
  			kfree_skb(bcsp->rx_skb);

  	} else if (pass_up == 1) {

  		/* Pull out BCSP hdr */
  		skb_pull(bcsp->rx_skb, 4);

  		hci_recv_frame(hu->hdev, bcsp->rx_skb);

  	} else {
  		/* ignore packet payload of already ACKed re-transmitted
  		 * packets or when a packet was missed in the BCSP window
  		 */
  		kfree_skb(bcsp->rx_skb);

  	}

  	bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
  	bcsp->rx_skb = NULL;
  }

  static u16 bscp_get_crc(struct bcsp_struct *bcsp)
  {
  	return get_unaligned_be16(&bcsp->rx_skb->data[bcsp->rx_skb->len - 2]);
  }

  /* Recv data */

  static int bcsp_recv(struct hci_uart *hu, const void *data, int count)

  {
  	struct bcsp_struct *bcsp = hu->priv;

  	const unsigned char *ptr;

  	BT_DBG("hu %p count %d rx_state %d rx_count %ld",

  	       hu, count, bcsp->rx_state, bcsp->rx_count);

  
  	ptr = data;
  	while (count) {
  		if (bcsp->rx_count) {
  			if (*ptr == 0xc0) {
  				BT_ERR("Short BCSP packet");
  				kfree_skb(bcsp->rx_skb);

  				bcsp->rx_skb = NULL;

  				bcsp->rx_state = BCSP_W4_PKT_START;
  				bcsp->rx_count = 0;
  			} else
  				bcsp_unslip_one_byte(bcsp, *ptr);
  
  			ptr++; count--;
  			continue;
  		}
  
  		switch (bcsp->rx_state) {
  		case BCSP_W4_BCSP_HDR:

  			if ((0xff & (u8)~(bcsp->rx_skb->data[0] + bcsp->rx_skb->data[1] +
  			    bcsp->rx_skb->data[2])) != bcsp->rx_skb->data[3]) {

  				BT_ERR("Error in BCSP hdr checksum");
  				kfree_skb(bcsp->rx_skb);

  				bcsp->rx_skb = NULL;

  				bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
  				bcsp->rx_count = 0;
  				continue;
  			}

  			bcsp->rx_state = BCSP_W4_DATA;

  			bcsp->rx_count = (bcsp->rx_skb->data[1] >> 4) +

  					(bcsp->rx_skb->data[2] << 4);	/* May be 0 */
  			continue;
  
  		case BCSP_W4_DATA:
  			if (bcsp->rx_skb->data[0] & 0x40) {	/* pkt with crc */
  				bcsp->rx_state = BCSP_W4_CRC;
  				bcsp->rx_count = 2;
  			} else
  				bcsp_complete_rx_pkt(hu);
  			continue;
  
  		case BCSP_W4_CRC:

  			if (bitrev16(bcsp->message_crc) != bscp_get_crc(bcsp)) {

  				BT_ERR("Checksum failed: computed %04x received %04x",

  				       bitrev16(bcsp->message_crc),
  				       bscp_get_crc(bcsp));

  
  				kfree_skb(bcsp->rx_skb);

  				bcsp->rx_skb = NULL;

  				bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
  				bcsp->rx_count = 0;
  				continue;
  			}
  			skb_trim(bcsp->rx_skb, bcsp->rx_skb->len - 2);
  			bcsp_complete_rx_pkt(hu);
  			continue;
  
  		case BCSP_W4_PKT_DELIMITER:
  			switch (*ptr) {
  			case 0xc0:
  				bcsp->rx_state = BCSP_W4_PKT_START;
  				break;
  			default:
  				/*BT_ERR("Ignoring byte %02x", *ptr);*/
  				break;
  			}
  			ptr++; count--;
  			break;
  
  		case BCSP_W4_PKT_START:
  			switch (*ptr) {
  			case 0xc0:
  				ptr++; count--;
  				break;
  
  			default:
  				bcsp->rx_state = BCSP_W4_BCSP_HDR;
  				bcsp->rx_count = 4;
  				bcsp->rx_esc_state = BCSP_ESCSTATE_NOESC;
  				BCSP_CRC_INIT(bcsp->message_crc);

  				/* Do not increment ptr or decrement count

  				 * Allocate packet. Max len of a BCSP pkt=
  				 * 0xFFF (payload) +4 (header) +2 (crc)
  				 */

  
  				bcsp->rx_skb = bt_skb_alloc(0x1005, GFP_ATOMIC);
  				if (!bcsp->rx_skb) {
  					BT_ERR("Can't allocate mem for new packet");
  					bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
  					bcsp->rx_count = 0;
  					return 0;
  				}

  				break;
  			}
  			break;
  		}
  	}
  	return count;
  }
  
  	/* Arrange to retransmit all messages in the relq. */

  static void bcsp_timed_event(struct timer_list *t)

  {

  	struct bcsp_struct *bcsp = from_timer(bcsp, t, tbcsp);
  	struct hci_uart *hu = bcsp->hu;

  	struct sk_buff *skb;
  	unsigned long flags;
  
  	BT_DBG("hu %p retransmitting %u pkts", hu, bcsp->unack.qlen);

  	spin_lock_irqsave_nested(&bcsp->unack.lock, flags, SINGLE_DEPTH_NESTING);

  
  	while ((skb = __skb_dequeue_tail(&bcsp->unack)) != NULL) {
  		bcsp->msgq_txseq = (bcsp->msgq_txseq - 1) & 0x07;
  		skb_queue_head(&bcsp->rel, skb);
  	}
  
  	spin_unlock_irqrestore(&bcsp->unack.lock, flags);
  
  	hci_uart_tx_wakeup(hu);
  }
  
  static int bcsp_open(struct hci_uart *hu)
  {
  	struct bcsp_struct *bcsp;
  
  	BT_DBG("hu %p", hu);

  	bcsp = kzalloc(sizeof(*bcsp), GFP_KERNEL);

  	if (!bcsp)
  		return -ENOMEM;

  
  	hu->priv = bcsp;

  	bcsp->hu = hu;

  	skb_queue_head_init(&bcsp->unack);
  	skb_queue_head_init(&bcsp->rel);
  	skb_queue_head_init(&bcsp->unrel);

  	timer_setup(&bcsp->tbcsp, bcsp_timed_event, 0);

  
  	bcsp->rx_state = BCSP_W4_PKT_DELIMITER;

  	if (txcrc)
  		bcsp->use_crc = 1;

  	return 0;
  }
  
  static int bcsp_close(struct hci_uart *hu)
  {
  	struct bcsp_struct *bcsp = hu->priv;

  
  	del_timer_sync(&bcsp->tbcsp);

  	hu->priv = NULL;
  
  	BT_DBG("hu %p", hu);
  
  	skb_queue_purge(&bcsp->unack);
  	skb_queue_purge(&bcsp->rel);
  	skb_queue_purge(&bcsp->unrel);

  	if (bcsp->rx_skb) {
  		kfree_skb(bcsp->rx_skb);
  		bcsp->rx_skb = NULL;
  	}

  	kfree(bcsp);
  	return 0;
  }

  static const struct hci_uart_proto bcsp = {

  	.id		= HCI_UART_BCSP,

  	.name		= "BCSP",

  	.open		= bcsp_open,
  	.close		= bcsp_close,
  	.enqueue	= bcsp_enqueue,
  	.dequeue	= bcsp_dequeue,
  	.recv		= bcsp_recv,
  	.flush		= bcsp_flush

  };

  int __init bcsp_init(void)

  {

  	return hci_uart_register_proto(&bcsp);

  }

  int __exit bcsp_deinit(void)

  {
  	return hci_uart_unregister_proto(&bcsp);
  }

  module_param(txcrc, bool, 0644);
  MODULE_PARM_DESC(txcrc, "Transmit CRC with every BCSP packet");

  module_param(hciextn, bool, 0644);
  MODULE_PARM_DESC(hciextn, "Convert HCI Extensions into BCSP packets");