Bluetooth: A2MP: Process A2MP Discover Request

Adds helper functions to count HCI devs and process A2MP Discover
Request, code makes sure that first controller in the list is
BREDR one. Trace is shown below:

...
> ACL data: handle 11 flags 0x02 dlen 16
    A2MP: Discover req: mtu/mps 670 mask: 0x0000
< ACL data: handle 11 flags 0x00 dlen 22
    A2MP: Discover rsp: mtu/mps 670 mask: 0x0000
      Controller list:
        id 0 type 0 (BR-EDR) status 0x01 (Bluetooth only)
        id 1 type 1 (802.11 AMP) status 0x01 (Bluetooth only)
...
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

include/net/bluetooth/a2mp.h

@@ -15,6 +15,8 @@
 #ifndef __A2MP_H
 #define __A2MP_H
 
+#define A2MP_FEAT_EXT	0x8000
+
 struct amp_mgr {
 	struct l2cap_conn	*l2cap_conn;
 	struct l2cap_chan	*a2mp_chan;

include/net/bluetooth/hci.h

@@ -59,6 +59,9 @@
 #define HCI_BREDR	0x00
 #define HCI_AMP		0x01
 
+/* First BR/EDR Controller shall have ID = 0 */
+#define HCI_BREDR_ID	0
+
 /* HCI device quirks */
 enum {
 	HCI_QUIRK_RESET_ON_CLOSE,

include/net/bluetooth/hci_core.h

@@ -641,6 +641,19 @@ static inline void hci_set_drvdata(struct hci_dev *hdev, void *data)
 	dev_set_drvdata(&hdev->dev, data);
 }
 
+/* hci_dev_list shall be locked */
+static inline uint8_t __hci_num_ctrl(void)
+{
+	uint8_t count = 0;
+	struct list_head *p;
+
+	list_for_each(p, &hci_dev_list) {
+		count++;
+	}
+
+	return count;
+}
+
 struct hci_dev *hci_dev_get(int index);
 struct hci_dev *hci_get_route(bdaddr_t *src, bdaddr_t *dst);
 

net/bluetooth/a2mp.c

@@ -63,6 +63,36 @@ static void a2mp_send(struct amp_mgr *mgr, u8 code, u8 ident, u16 len,
 	kfree(cmd);
 }
 
+static inline void __a2mp_cl_bredr(struct a2mp_cl *cl)
+{
+	cl->id = 0;
+	cl->type = 0;
+	cl->status = 1;
+}
+
+/* hci_dev_list shall be locked */
+static void __a2mp_add_cl(struct amp_mgr *mgr, struct a2mp_cl *cl, u8 num_ctrl)
+{
+	int i = 0;
+	struct hci_dev *hdev;
+
+	__a2mp_cl_bredr(cl);
+
+	list_for_each_entry(hdev, &hci_dev_list, list) {
+		/* Iterate through AMP controllers */
+		if (hdev->id == HCI_BREDR_ID)
+			continue;
+
+		/* Starting from second entry */
+		if (++i >= num_ctrl)
+			return;
+
+		cl[i].id = hdev->id;
+		cl[i].type = hdev->amp_type;
+		cl[i].status = hdev->amp_status;
+	}
+}
+
 /* Processing A2MP messages */
 static int a2mp_command_rej(struct amp_mgr *mgr, struct sk_buff *skb,
 			    struct a2mp_cmd *hdr)
@@ -79,6 +109,58 @@ static int a2mp_command_rej(struct amp_mgr *mgr, struct sk_buff *skb,
 	return 0;
 }
 
+static int a2mp_discover_req(struct amp_mgr *mgr, struct sk_buff *skb,
+			     struct a2mp_cmd *hdr)
+{
+	struct a2mp_discov_req *req = (void *) skb->data;
+	u16 len = le16_to_cpu(hdr->len);
+	struct a2mp_discov_rsp *rsp;
+	u16 ext_feat;
+	u8 num_ctrl;
+
+	if (len < sizeof(*req))
+		return -EINVAL;
+
+	skb_pull(skb, sizeof(*req));
+
+	ext_feat = le16_to_cpu(req->ext_feat);
+
+	BT_DBG("mtu %d efm 0x%4.4x", le16_to_cpu(req->mtu), ext_feat);
+
+	/* check that packet is not broken for now */
+	while (ext_feat & A2MP_FEAT_EXT) {
+		if (len < sizeof(ext_feat))
+			return -EINVAL;
+
+		ext_feat = get_unaligned_le16(skb->data);
+		BT_DBG("efm 0x%4.4x", ext_feat);
+		len -= sizeof(ext_feat);
+		skb_pull(skb, sizeof(ext_feat));
+	}
+
+	read_lock(&hci_dev_list_lock);
+
+	num_ctrl = __hci_num_ctrl();
+	len = num_ctrl * sizeof(struct a2mp_cl) + sizeof(*rsp);
+	rsp = kmalloc(len, GFP_ATOMIC);
+	if (!rsp) {
+		read_unlock(&hci_dev_list_lock);
+		return -ENOMEM;
+	}
+
+	rsp->mtu = __constant_cpu_to_le16(L2CAP_A2MP_DEFAULT_MTU);
+	rsp->ext_feat = 0;
+
+	__a2mp_add_cl(mgr, rsp->cl, num_ctrl);
+
+	read_unlock(&hci_dev_list_lock);
+
+	a2mp_send(mgr, A2MP_DISCOVER_RSP, hdr->ident, len, rsp);
+
+	kfree(rsp);
+	return 0;
+}
+
 /* Handle A2MP signalling */
 static int a2mp_chan_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
 {
@@ -109,6 +191,9 @@ static int a2mp_chan_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
 			break;
 
 		case A2MP_DISCOVER_REQ:
+			err = a2mp_discover_req(mgr, skb, hdr);
+			break;
+
 		case A2MP_CHANGE_NOTIFY:
 		case A2MP_GETINFO_REQ:
 		case A2MP_GETAMPASSOC_REQ: