Skip to content

Commit

Permalink
Bluetooth: Add basic packet parsing to Three-wire UART driver
Browse files Browse the repository at this point in the history 
This patch adds basic packet parsing to the Three-wire UART HCI driver
for packets received from the controller.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
  • Loading branch information
Johan Hedberg authored and Gustavo Padovan committed Jul 17, 2012
1 parent 3f27e95 commit bc1f35b
Showing 1 changed file with 222 additions and 8 deletions.
230 changes: 222 additions & 8 deletions drivers/bluetooth/hci_h5.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,20 +34,37 @@

#define H5_ACK_TIMEOUT msecs_to_jiffies(250)

/*
* Maximum Three-wire packet:
* 4 byte header + max value for 12-bit length + 2 bytes for CRC
*/
#define H5_MAX_LEN (4 + 0xfff + 2)

#define SLIP_DELIMITER 0xc0
#define SLIP_ESC 0xdb
#define SLIP_ESC_DELIM 0xdc
#define SLIP_ESC_ESC 0xdd

struct h5 {
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 */
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 */

struct sk_buff *rx_skb;
struct sk_buff *rx_skb; /* Receive buffer */
size_t rx_pending; /* Expecting more bytes */
bool rx_esc; /* SLIP escape mode */

struct timer_list timer; /* Retransmission timer */
int (*rx_func) (struct hci_uart *hu, u8 c);

bool txack_req;
struct timer_list timer; /* Retransmission timer */

u8 msgq_txseq;
bool txack_req;

u8 msgq_txseq;
};

static void h5_reset_rx(struct h5 *h5);

static void h5_timed_event(unsigned long arg)
{
struct hci_uart *hu = (struct hci_uart *) arg;
Expand Down Expand Up @@ -85,6 +102,8 @@ static int h5_open(struct hci_uart *hu)
skb_queue_head_init(&h5->rel);
skb_queue_head_init(&h5->unrel);

h5_reset_rx(h5);

init_timer(&h5->timer);
h5->timer.function = h5_timed_event;
h5->timer.data = (unsigned long) hu;
Expand All @@ -107,9 +126,204 @@ static int h5_close(struct hci_uart *hu)
return 0;
}

static void h5_handle_internal_rx(struct hci_uart *hu)
{
BT_DBG("%s", hu->hdev->name);
}

static void h5_complete_rx_pkt(struct hci_uart *hu)
{
struct h5 *h5 = hu->priv;
u8 pkt_type;

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

pkt_type = h5->rx_skb->data[1] & 0x0f;

switch (pkt_type) {
case HCI_EVENT_PKT:
case HCI_ACLDATA_PKT:
case HCI_SCODATA_PKT:
bt_cb(h5->rx_skb)->pkt_type = pkt_type;

/* Remove Three-wire header */
skb_pull(h5->rx_skb, 4);

hci_recv_frame(h5->rx_skb);
h5->rx_skb = NULL;

break;

default:
h5_handle_internal_rx(hu);
break;
}

h5_reset_rx(h5);
}

static int h5_rx_crc(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;

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

h5_complete_rx_pkt(hu);
h5_reset_rx(h5);

return 0;
}

static int h5_rx_payload(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;
const unsigned char *hdr = h5->rx_skb->data;

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

if ((hdr[0] >> 4) & 0x01) {
h5->rx_func = h5_rx_crc;
h5->rx_pending = 2;
} else {
h5_complete_rx_pkt(hu);
h5_reset_rx(h5);
}

return 0;
}

static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;
const unsigned char *hdr = h5->rx_skb->data;

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

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

h5->rx_func = h5_rx_payload;
h5->rx_pending = ((hdr[1] >> 4) & 0xff) + (hdr[2] << 4);

return 0;
}

static int h5_rx_pkt_start(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;

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

if (c == SLIP_DELIMITER)
return 1;

h5->rx_func = h5_rx_3wire_hdr;
h5->rx_pending = 4;

h5->rx_skb = bt_skb_alloc(H5_MAX_LEN, GFP_ATOMIC);
if (!h5->rx_skb) {
BT_ERR("Can't allocate mem for new packet");
h5_reset_rx(h5);
return -ENOMEM;
}

h5->rx_skb->dev = (void *) hu->hdev;

return 0;
}

static int h5_rx_delimiter(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;

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

if (c == SLIP_DELIMITER)
h5->rx_func = h5_rx_pkt_start;

return 1;
}

static void h5_unslip_one_byte(struct h5 *h5, unsigned char c)
{
const u8 delim = SLIP_DELIMITER, esc = SLIP_ESC;
const u8 *byte = &c;

if (!h5->rx_esc && c == SLIP_ESC) {
h5->rx_esc = true;
return;
}

if (h5->rx_esc) {
switch (c) {
case SLIP_ESC_DELIM:
byte = &delim;
break;
case SLIP_ESC_ESC:
byte = &esc;
break;
default:
BT_ERR("Invalid esc byte 0x%02hhx", c);
h5_reset_rx(h5);
return;
}

h5->rx_esc = false;
}

memcpy(skb_put(h5->rx_skb, 1), byte, 1);
h5->rx_pending--;

BT_DBG("unsliped 0x%02hhx", *byte);
}

static void h5_reset_rx(struct h5 *h5)
{
if (h5->rx_skb) {
kfree_skb(h5->rx_skb);
h5->rx_skb = NULL;
}

h5->rx_func = h5_rx_delimiter;
h5->rx_pending = 0;
h5->rx_esc = false;
}

static int h5_recv(struct hci_uart *hu, void *data, int count)
{
return -ENOSYS;
struct h5 *h5 = hu->priv;
unsigned char *ptr = data;

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

while (count > 0) {
int processed;

if (h5->rx_pending > 0) {
if (*ptr == SLIP_DELIMITER) {
BT_ERR("Too short H5 packet");
h5_reset_rx(h5);
continue;
}

h5_unslip_one_byte(h5, *ptr);

ptr++; count--;
continue;
}

processed = h5->rx_func(hu, *ptr);
if (processed < 0)
return processed;

ptr += processed;
count -= processed;
}

return 0;
}

static int h5_enqueue(struct hci_uart *hu, struct sk_buff *skb)
Expand Down

0 comments on commit bc1f35b

Please sign in to comment.