--- /dev/null
+/*
+ *
+ *  Generic Bluetooth HCI UART driver
+ *
+ *  Copyright (C) 2015-2018  Intel Corporation
+ *
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <asm/unaligned.h>
+
+struct h4_recv_pkt {
+       u8  type;       /* Packet type */
+       u8  hlen;       /* Header length */
+       u8  loff;       /* Data length offset in header */
+       u8  lsize;      /* Data length field size */
+       u16 maxlen;     /* Max overall packet length */
+       int (*recv)(struct hci_dev *hdev, struct sk_buff *skb);
+};
+
+#define H4_RECV_ACL \
+       .type = HCI_ACLDATA_PKT, \
+       .hlen = HCI_ACL_HDR_SIZE, \
+       .loff = 2, \
+       .lsize = 2, \
+       .maxlen = HCI_MAX_FRAME_SIZE \
+
+#define H4_RECV_SCO \
+       .type = HCI_SCODATA_PKT, \
+       .hlen = HCI_SCO_HDR_SIZE, \
+       .loff = 2, \
+       .lsize = 1, \
+       .maxlen = HCI_MAX_SCO_SIZE
+
+#define H4_RECV_EVENT \
+       .type = HCI_EVENT_PKT, \
+       .hlen = HCI_EVENT_HDR_SIZE, \
+       .loff = 1, \
+       .lsize = 1, \
+       .maxlen = HCI_MAX_EVENT_SIZE
+
+static inline struct sk_buff *h4_recv_buf(struct hci_dev *hdev,
+                                         struct sk_buff *skb,
+                                         const unsigned char *buffer,
+                                         int count,
+                                         const struct h4_recv_pkt *pkts,
+                                         int pkts_count)
+{
+       while (count) {
+               int i, len;
+
+               if (!count)
+                       break;
+
+               if (!skb) {
+                       for (i = 0; i < pkts_count; i++) {
+                               if (buffer[0] != (&pkts[i])->type)
+                                       continue;
+
+                               skb = bt_skb_alloc((&pkts[i])->maxlen,
+                                                  GFP_ATOMIC);
+                               if (!skb)
+                                       return ERR_PTR(-ENOMEM);
+
+                               hci_skb_pkt_type(skb) = (&pkts[i])->type;
+                               hci_skb_expect(skb) = (&pkts[i])->hlen;
+                               break;
+                       }
+
+                       /* Check for invalid packet type */
+                       if (!skb)
+                               return ERR_PTR(-EILSEQ);
+
+                       count -= 1;
+                       buffer += 1;
+               }
+
+               len = min_t(uint, hci_skb_expect(skb) - skb->len, count);
+               skb_put_data(skb, buffer, len);
+
+               count -= len;
+               buffer += len;
+
+               /* Check for partial packet */
+               if (skb->len < hci_skb_expect(skb))
+                       continue;
+
+               for (i = 0; i < pkts_count; i++) {
+                       if (hci_skb_pkt_type(skb) == (&pkts[i])->type)
+                               break;
+               }
+
+               if (i >= pkts_count) {
+                       kfree_skb(skb);
+                       return ERR_PTR(-EILSEQ);
+               }
+
+               if (skb->len == (&pkts[i])->hlen) {
+                       u16 dlen;
+
+                       switch ((&pkts[i])->lsize) {
+                       case 0:
+                               /* No variable data length */
+                               dlen = 0;
+                               break;
+                       case 1:
+                               /* Single octet variable length */
+                               dlen = skb->data[(&pkts[i])->loff];
+                               hci_skb_expect(skb) += dlen;
+
+                               if (skb_tailroom(skb) < dlen) {
+                                       kfree_skb(skb);
+                                       return ERR_PTR(-EMSGSIZE);
+                               }
+                               break;
+                       case 2:
+                               /* Double octet variable length */
+                               dlen = get_unaligned_le16(skb->data +
+                                                         (&pkts[i])->loff);
+                               hci_skb_expect(skb) += dlen;
+
+                               if (skb_tailroom(skb) < dlen) {
+                                       kfree_skb(skb);
+                                       return ERR_PTR(-EMSGSIZE);
+                               }
+                               break;
+                       default:
+                               /* Unsupported variable length */
+                               kfree_skb(skb);
+                               return ERR_PTR(-EILSEQ);
+                       }
+
+                       if (!dlen) {
+                               /* No more data, complete frame */
+                               (&pkts[i])->recv(hdev, skb);
+                               skb = NULL;
+                       }
+               } else {
+                       /* Complete frame */
+                       (&pkts[i])->recv(hdev, skb);
+                       skb = NULL;
+               }
+       }
+
+       return skb;
+}