hci_bcsp.c

linux蓝牙USB HCI层驱动,简单明了非常适合蓝牙开发人员学习

	for (i = 0, skb = ((struct sk_buff *) &bcsp->unack)->next; i < pkts_to_be_removed
			&& skb != (struct sk_buff *) &bcsp->unack; i++) {
		struct sk_buff *nskb;

		nskb = skb->next;
		__skb_unlink(skb, &bcsp->unack);
		kfree_skb(skb);
		skb = nskb;
	}
	if (bcsp->unack.qlen == 0)
		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;
		memcpy(skb_put(nskb, 4), conf_rsp_pkt, 4);
		nskb->pkt_type = 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:
			memcpy(skb_put(bcsp->rx_skb, 1), &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:
			memcpy(skb_put(bcsp->rx_skb, 1), &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:
			memcpy(skb_put(bcsp->rx_skb, 1), &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 inline void bcsp_complete_rx_pkt(struct hci_uart *hu)
{
	struct bcsp_struct *bcsp = hu->priv;
	int pass_up;

	if (bcsp->rx_skb->data[0] & 0x80) {	/* reliable pkt */
		BT_DBG("Received seqno %u from card", bcsp->rxseq_txack);
		bcsp->rxseq_txack++;
		bcsp->rxseq_txack %= 0x8;
		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);

	bcsp_pkt_cull(bcsp);
	if ((bcsp->rx_skb->data[1] & 0x0f) == 6 &&
			bcsp->rx_skb->data[0] & 0x80) {
		bcsp->rx_skb->pkt_type = HCI_ACLDATA_PKT;
		pass_up = 1;
	} else if ((bcsp->rx_skb->data[1] & 0x0f) == 5 &&
			bcsp->rx_skb->data[0] & 0x80) {
		bcsp->rx_skb->pkt_type = HCI_EVENT_PKT;
		pass_up = 1;
	} else if ((bcsp->rx_skb->data[1] & 0x0f) == 7) {
		bcsp->rx_skb->pkt_type = 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) {
		if ((bcsp->rx_skb->data[1] & 0x0f) != 0 &&
	    		(bcsp->rx_skb->data[1] & 0x0f) != 1) {
			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 {
		/* Pull out BCSP hdr */
		skb_pull(bcsp->rx_skb, 4);

		hci_recv_frame(bcsp->rx_skb);
	}
	bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
	bcsp->rx_skb = NULL;
}

/* Recv data */
static int bcsp_recv(struct hci_uart *hu, void *data, int count)
{
	struct bcsp_struct *bcsp = hu->priv;
	register unsigned char *ptr;

	BT_DBG("hu %p count %d rx_state %ld 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_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_state = BCSP_W4_PKT_DELIMITER;
				bcsp->rx_count = 0;
				continue;
			}
			if (bcsp->rx_skb->data[0] & 0x80	/* reliable pkt */
			    		&& (bcsp->rx_skb->data[0] & 0x07) != bcsp->rxseq_txack) {
				BT_ERR ("Out-of-order packet arrived, got %u expected %u",
					bcsp->rx_skb->data[0] & 0x07, bcsp->rxseq_txack);

				kfree_skb(bcsp->rx_skb);
				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 (bcsp_crc_reverse(bcsp->message_crc) !=
					(bcsp->rx_skb->data[bcsp->rx_skb->len - 2] << 8) +
					bcsp->rx_skb->data[bcsp->rx_skb->len - 1]) {

				BT_ERR ("Checksum failed: computed %04x received %04x",
					bcsp_crc_reverse(bcsp->message_crc),
				     	(bcsp->rx_skb-> data[bcsp->rx_skb->len - 2] << 8) +
				     	bcsp->rx_skb->data[bcsp->rx_skb->len - 1]);

				kfree_skb(bcsp->rx_skb);
				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 = bluez_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;
				}
				bcsp->rx_skb->dev = (void *) &hu->hdev;
				break;
			}
			break;
		}
	}
	return count;
}

	/* Arrange to retransmit all messages in the relq. */
static void bcsp_timed_event(unsigned long arg)
{
	struct hci_uart *hu = (struct hci_uart *) arg;
	struct bcsp_struct *bcsp = (struct bcsp_struct *) hu->priv;
	struct sk_buff *skb;
	unsigned long flags;

	BT_ERR("Timeout, retransmitting %u pkts", bcsp->unack.qlen);
	spin_lock_irqsave(&bcsp->unack.lock, flags);

	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 = kmalloc(sizeof(*bcsp), GFP_ATOMIC);
	if (!bcsp)
		return -ENOMEM;
	memset(bcsp, 0, sizeof(*bcsp));

	hu->priv = bcsp;
	skb_queue_head_init(&bcsp->unack);
	skb_queue_head_init(&bcsp->rel);
	skb_queue_head_init(&bcsp->unrel);

	init_timer(&bcsp->tbcsp);
	bcsp->tbcsp.function = bcsp_timed_event;
	bcsp->tbcsp.data     = (u_long) hu;

	bcsp->rx_state = BCSP_W4_PKT_DELIMITER;

	return 0;
}

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

	BT_DBG("hu %p", hu);

	skb_queue_purge(&bcsp->unack);
	skb_queue_purge(&bcsp->rel);
	skb_queue_purge(&bcsp->unrel);
	del_timer(&bcsp->tbcsp);

	kfree(bcsp);
	return 0;
}

static struct hci_uart_proto bcsp = {
	id:      HCI_UART_BCSP,
	open:    bcsp_open,
	close:   bcsp_close,
	enqueue: bcsp_enqueue,
	dequeue: bcsp_dequeue,
	recv:    bcsp_recv,
	flush:   bcsp_flush
};

int bcsp_init(void)
{
	return hci_uart_register_proto(&bcsp);
}

int bcsp_deinit(void)
{
	return hci_uart_unregister_proto(&bcsp);
}