Bluetooth: hci_h5: implement CRC data integrity

The UART-based H5 protocol supports CRC data integrity checks for
reliable packets. The host sets bit 5 in the configuration field of the
CONFIG link control message to indicate that CRC is supported. The
controller sets the same bit in the CONFIG RESPONSE message to indicate
that CRC may be used from then on.

Tested on a MangoPi MQ-Pro with a Realtek RTL8723DS Bluetooth controller
using the tip of the bluetooth-next tree.

Signed-off-by: Javier Nieto <jgnieto@cs.stanford.edu>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
index 7df69ccb660053ee63190eda6fac2d32b4033683..c5d45cf91f88274f5f17167b795904fe4f016800 100644 (file)
--- a/drivers/bluetooth/Kconfig
+++ b/drivers/bluetooth/Kconfig
@@ -188,6 +188,7 @@ config BT_HCIUART_3WIRE
        bool "Three-wire UART (H5) protocol support"
        depends on BT_HCIUART
        depends on BT_HCIUART_SERDEV
+       select CRC_CCITT
        help
          The HCI Three-wire UART Transport Layer makes it possible to
          user the Bluetooth HCI over a serial port interface. The HCI

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 863ee93dd8a8d97bfe959f3415f37093c2b9f369..43371f389fd2dbbd5f463b2f8c88c12a6ddbf02c 100644 (file)
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -7,6 +7,8 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/bitrev.h>
+#include <linux/crc-ccitt.h>
 #include <linux/errno.h>
 #include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
@@ -58,6 +60,7 @@ enum {
        H5_TX_ACK_REQ,          /* Pending ack to send */
        H5_WAKEUP_DISABLE,      /* Device cannot wake host */
        H5_HW_FLOW_CONTROL,     /* Use HW flow control */
+       H5_CRC,                 /* Use CRC */
 };
 
 struct h5 {
@@ -141,8 +144,8 @@ static void h5_link_control(struct hci_uart *hu, const void *data, size_t len)
 
 static u8 h5_cfg_field(struct h5 *h5)
 {
-       /* Sliding window size (first 3 bits) */
-       return h5->tx_win & 0x07;
+       /* Sliding window size (first 3 bits) and CRC request (fifth bit). */
+       return (h5->tx_win & 0x07) | 0x10;
 }
 
 static void h5_timed_event(struct timer_list *t)
@@ -361,8 +364,10 @@ static void h5_handle_internal_rx(struct hci_uart *hu)
                h5_link_control(hu, conf_rsp, 2);
                h5_link_control(hu, conf_req, 3);
        } else if (memcmp(data, conf_rsp, 2) == 0) {
-               if (H5_HDR_LEN(hdr) > 2)
+               if (H5_HDR_LEN(hdr) > 2) {
                        h5->tx_win = (data[2] & 0x07);
+                       assign_bit(H5_CRC, &h5->flags, data[2] & 0x10);
+               }
                BT_DBG("Three-wire init complete. tx_win %u", h5->tx_win);
                h5->state = H5_ACTIVE;
                hci_uart_init_ready(hu);
@@ -426,7 +431,24 @@ static void h5_complete_rx_pkt(struct hci_uart *hu)
 
 static int h5_rx_crc(struct hci_uart *hu, unsigned char c)
 {
-       h5_complete_rx_pkt(hu);
+       struct h5 *h5 = hu->priv;
+       const unsigned char *hdr = h5->rx_skb->data;
+       u16 crc;
+       __be16 crc_be;
+
+       crc = crc_ccitt(0xffff, hdr, 4 + H5_HDR_LEN(hdr));
+       crc = bitrev16(crc);
+
+       crc_be = cpu_to_be16(crc);
+
+       if (memcmp(&crc_be, hdr + 4 + H5_HDR_LEN(hdr), 2) != 0) {
+               bt_dev_err(hu->hdev, "Received packet with invalid CRC");
+               h5_reset_rx(h5);
+       } else {
+               /* Remove CRC bytes */
+               skb_trim(h5->rx_skb, 4 + H5_HDR_LEN(hdr));
+               h5_complete_rx_pkt(hu);
+       }
 
        return 0;
 }
@@ -557,6 +579,7 @@ static void h5_reset_rx(struct h5 *h5)
        h5->rx_func = h5_rx_delimiter;
        h5->rx_pending = 0;
        clear_bit(H5_RX_ESC, &h5->flags);
+       clear_bit(H5_CRC, &h5->flags);
 }
 
 static int h5_recv(struct hci_uart *hu, const void *data, int count)
@@ -687,6 +710,7 @@ static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
        struct h5 *h5 = hu->priv;
        struct sk_buff *nskb;
        u8 hdr[4];
+       u16 crc;
        int i;
 
        if (!valid_packet_type(pkt_type)) {
@@ -714,6 +738,7 @@ static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
        /* Reliable packet? */
        if (pkt_type == HCI_ACLDATA_PKT || pkt_type == HCI_COMMAND_PKT) {
                hdr[0] |= 1 << 7;
+               hdr[0] |= (test_bit(H5_CRC, &h5->flags) && 1) << 6;
                hdr[0] |= h5->tx_seq;
                h5->tx_seq = (h5->tx_seq + 1) % 8;
        }
@@ -733,6 +758,15 @@ static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
        for (i = 0; i < len; i++)
                h5_slip_one_byte(nskb, data[i]);
 
+       if (H5_HDR_CRC(hdr)) {
+               crc = crc_ccitt(0xffff, hdr, 4);
+               crc = crc_ccitt(crc, data, len);
+               crc = bitrev16(crc);
+
+               h5_slip_one_byte(nskb, (crc >> 8) & 0xff);
+               h5_slip_one_byte(nskb, crc & 0xff);
+       }
+
        h5_slip_delim(nskb);
 
        return nskb;