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Bluetooth: Add support for Three-wire Link Control packets
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This patch adds basic support for parsing and sending Three-wire UART
Link Control packets.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
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Johan Hedberg authored and Gustavo Padovan committed Jul 17, 2012
1 parent 43eb12d commit 40f1022
Showing 1 changed file with 79 additions and 17 deletions.
96 changes: 79 additions & 17 deletions drivers/bluetooth/hci_h5.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
#define H5_TXWINSIZE 4

#define H5_ACK_TIMEOUT msecs_to_jiffies(250)
#define H5_SYNC_TIMEOUT msecs_to_jiffies(100)

/*
* Maximum Three-wire packet:
Expand Down Expand Up @@ -65,14 +66,14 @@ struct h5 {
size_t rx_pending; /* Expecting more bytes */
bool rx_esc; /* SLIP escape mode */
u8 rx_ack; /* Last ack number received */
u8 rx_seq; /* Last seq number received */

int (*rx_func) (struct hci_uart *hu, u8 c);

struct timer_list timer; /* Retransmission timer */

bool tx_ack_req; /* Pending ack to send */
u8 tx_seq; /* Next seq number to send */
u8 tx_ack; /* Next ack number to send */
};

static void h5_reset_rx(struct h5 *h5);
Expand All @@ -98,9 +99,26 @@ static void h5_timed_event(unsigned long arg)
hci_uart_tx_wakeup(hu);
}

static void h5_link_control(struct hci_uart *hu, const void *data, size_t len)
{
struct h5 *h5 = hu->priv;
struct sk_buff *nskb;

nskb = alloc_skb(3, GFP_ATOMIC);
if (!nskb)
return;

bt_cb(nskb)->pkt_type = HCI_3WIRE_LINK_PKT;

memcpy(skb_put(nskb, len), data, len);

skb_queue_tail(&h5->unrel, nskb);
}

static int h5_open(struct hci_uart *hu)
{
struct h5 *h5;
const unsigned char sync[] = { 0x01, 0x7e };

BT_DBG("hu %p", hu);

Expand All @@ -120,6 +138,10 @@ static int h5_open(struct hci_uart *hu)
h5->timer.function = h5_timed_event;
h5->timer.data = (unsigned long) hu;

/* Send initial sync request */
h5_link_control(hu, sync, sizeof(sync));
mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);

return 0;
}

Expand Down Expand Up @@ -148,6 +170,8 @@ static void h5_pkt_cull(struct h5 *h5)
spin_lock_irqsave(&h5->unack.lock, flags);

to_remove = skb_queue_len(&h5->unack);
if (to_remove == 0)
goto unlock;

seq = h5->tx_seq;

Expand All @@ -174,12 +198,44 @@ static void h5_pkt_cull(struct h5 *h5)
if (skb_queue_empty(&h5->unack))
del_timer(&h5->timer);

unlock:
spin_unlock_irqrestore(&h5->unack.lock, flags);
}

static void h5_handle_internal_rx(struct hci_uart *hu)
{
struct h5 *h5 = hu->priv;
const unsigned char sync_req[] = { 0x01, 0x7e };
const unsigned char sync_rsp[] = { 0x02, 0x7d };
const unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
const unsigned char conf_rsp[] = { 0x04, 0x7b, 0x01 };
const unsigned char *hdr = h5->rx_skb->data;
const unsigned char *data = &h5->rx_skb->data[4];

BT_DBG("%s", hu->hdev->name);

if (H5_HDR_PKT_TYPE(hdr) != HCI_3WIRE_LINK_PKT)
return;

if (H5_HDR_LEN(hdr) < 2)
return;

if (memcmp(data, sync_req, 2) == 0) {
h5_link_control(hu, sync_rsp, 2);
} else if (memcmp(data, sync_rsp, 2) == 0) {
h5_link_control(hu, conf_req, 3);
} else if (memcmp(data, conf_req, 2) == 0) {
h5_link_control(hu, conf_rsp, 2);
h5_link_control(hu, conf_req, 3);
} else if (memcmp(data, conf_rsp, 2) == 0) {
BT_DBG("Three-wire init sequence complete");
return;
} else {
BT_DBG("Link Control: 0x%02hhx 0x%02hhx", data[0], data[1]);
return;
}

hci_uart_tx_wakeup(hu);
}

static void h5_complete_rx_pkt(struct hci_uart *hu)
Expand All @@ -190,8 +246,9 @@ static void h5_complete_rx_pkt(struct hci_uart *hu)
BT_DBG("%s", hu->hdev->name);

if (H5_HDR_RELIABLE(hdr)) {
h5->tx_seq = (h5->tx_seq + 1) % 8;
h5->tx_ack = (h5->tx_ack + 1) % 8;
h5->tx_ack_req = true;
hci_uart_tx_wakeup(hu);
}

h5->rx_ack = H5_HDR_ACK(hdr);
Expand Down Expand Up @@ -257,15 +314,20 @@ static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)

BT_DBG("%s 0x%02hhx", hu->hdev->name, c);

BT_DBG("%s rx: seq %u ack %u crc %u rel %u type %u len %u",
hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
H5_HDR_LEN(hdr));

if (((hdr[0] + hdr[1] + hdr[2] + hdr[3]) & 0xff) != 0xff) {
BT_ERR("Invalid header checksum");
h5_reset_rx(h5);
return 0;
}

if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_seq) {
if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
BT_ERR("Out-of-order packet arrived (%u != %u)",
H5_HDR_SEQ(hdr), h5->tx_seq);
H5_HDR_SEQ(hdr), h5->tx_ack);
h5_reset_rx(h5);
return 0;
}
Expand Down Expand Up @@ -444,9 +506,10 @@ static void h5_slip_one_byte(struct sk_buff *skb, u8 c)
}
}

static struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,
static struct sk_buff *h5_build_pkt(struct hci_uart *hu, bool rel, u8 pkt_type,
const u8 *data, size_t len)
{
struct h5 *h5 = hu->priv;
struct sk_buff *nskb;
u8 hdr[4];
int i;
Expand All @@ -465,7 +528,7 @@ static struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,

h5_slip_delim(nskb);

hdr[0] = h5->rx_seq << 3;
hdr[0] = h5->tx_ack << 3;
h5->tx_ack_req = false;

if (rel) {
Expand All @@ -478,6 +541,11 @@ static struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,
hdr[2] = len >> 4;
hdr[3] = ~((hdr[0] + hdr[1] + hdr[2]) & 0xff);

BT_DBG("%s tx: seq %u ack %u crc %u rel %u type %u len %u",
hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
H5_HDR_LEN(hdr));

for (i = 0; i < 4; i++)
h5_slip_one_byte(nskb, hdr[i]);

Expand All @@ -489,7 +557,7 @@ static struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,
return nskb;
}

static struct sk_buff *h5_prepare_pkt(struct h5 *h5, u8 pkt_type,
static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
const u8 *data, size_t len)
{
bool rel;
Expand All @@ -509,13 +577,7 @@ static struct sk_buff *h5_prepare_pkt(struct h5 *h5, u8 pkt_type,
return NULL;
}

return h5_build_pkt(h5, rel, pkt_type, data, len);
}

static struct sk_buff *h5_prepare_ack(struct h5 *h5)
{
h5->tx_ack_req = false;
return NULL;
return h5_build_pkt(hu, rel, pkt_type, data, len);
}

static struct sk_buff *h5_dequeue(struct hci_uart *hu)
Expand All @@ -525,7 +587,7 @@ static struct sk_buff *h5_dequeue(struct hci_uart *hu)
struct sk_buff *skb, *nskb;

if ((skb = skb_dequeue(&h5->unrel)) != NULL) {
nskb = h5_prepare_pkt(h5, bt_cb(skb)->pkt_type,
nskb = h5_prepare_pkt(hu, bt_cb(skb)->pkt_type,
skb->data, skb->len);
if (nskb) {
kfree_skb(skb);
Expand All @@ -542,7 +604,7 @@ static struct sk_buff *h5_dequeue(struct hci_uart *hu)
goto unlock;

if ((skb = skb_dequeue(&h5->rel)) != NULL) {
nskb = h5_prepare_pkt(h5, bt_cb(skb)->pkt_type,
nskb = h5_prepare_pkt(hu, bt_cb(skb)->pkt_type,
skb->data, skb->len);
if (nskb) {
__skb_queue_tail(&h5->unack, skb);
Expand All @@ -559,7 +621,7 @@ static struct sk_buff *h5_dequeue(struct hci_uart *hu)
spin_unlock_irqrestore(&h5->unack.lock, flags);

if (h5->tx_ack_req)
return h5_prepare_ack(h5);
return h5_prepare_pkt(hu, HCI_3WIRE_ACK_PKT, NULL, 0);

return NULL;
}
Expand Down

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