Bluetooth: Add basic packet parsing to Three-wire UART driver

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>

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index ae1bd32..ddf7ebb 100644 (file)
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -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;
@@ -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;
@@ -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)