Re: [RFC 2/4] Bluetooth: Connection Parameter Update Procedure

[Marcel Holtmann <marcel@holtmann.org>]

Hi Andre,

> This patch adds support for LE Connection Parameters Request Link
> Layer control procedure introduced in Core spec 4.1. This procedure
> allows a Peripheral or Central to update the Link Layer connection
> parameters of an established connection.
> 
> Regarding the acceptance of connection parameters, the LL procedure
> follows the same approach of L2CAP procedure (see l2cap_conn_param_
> update_req function). We accept any connection parameters values as
> long as they are within the valid range.
> 
> Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
> ---
> include/net/bluetooth/hci.h | 28 +++++++++++++++++++++++++
> net/bluetooth/hci_event.c   | 50 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 78 insertions(+)
> 
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index cc2e88d..59bad0b 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -355,6 +355,7 @@ enum {
> #define HCI_LK_AUTH_COMBINATION_P256	0x08
> 
> /* ---- HCI Error Codes ---- */
> +#define HCI_ERROR_UNKNOWN_CONN_ID	0x02
> #define HCI_ERROR_AUTH_FAILURE		0x05
> #define HCI_ERROR_MEMORY_EXCEEDED	0x07
> #define HCI_ERROR_CONNECTION_TIMEOUT	0x08
> @@ -364,6 +365,7 @@ enum {
> #define HCI_ERROR_REMOTE_POWER_OFF	0x15
> #define HCI_ERROR_LOCAL_HOST_TERM	0x16
> #define HCI_ERROR_PAIRING_NOT_ALLOWED	0x18
> +#define HCI_ERROR_INVALID_LL_PARAMS	0x1E
> #define HCI_ERROR_ADVERTISING_TIMEOUT	0x3c
> 
> /* Flow control modes */
> @@ -1288,6 +1290,23 @@ struct hci_rp_le_read_supported_states {
> 	__u8	le_states[8];
> } __packed;
> 
> +#define HCI_OP_LE_CONN_PARAM_REQ_REPLY	0x2020
> +struct hci_cp_le_conn_param_req_reply {
> +	__le16	handle;
> +	__le16	interval_min;
> +	__le16	interval_max;
> +	__le16	latency;
> +	__le16	timeout;
> +	__le16	min_ce_len;
> +	__le16	max_ce_len;
> +} __packed;
> +
> +#define HCI_OP_LE_CONN_PARAM_REQ_NEG_REPLY	0x2021
> +struct hci_cp_le_conn_param_req_neg_reply {
> +	__le16	handle;
> +	__u8	reason;
> +} __packed;
> +
> /* ---- HCI Events ---- */
> #define HCI_EV_INQUIRY_COMPLETE		0x01
> 
> @@ -1683,6 +1702,15 @@ struct hci_ev_le_ltk_req {
> 	__le16	ediv;
> } __packed;
> 
> +#define HCI_EV_LE_REMOTE_CONN_PARAM_REQ	0x06
> +struct hci_ev_le_remote_conn_param_req {
> +	__le16 handle;
> +	__le16 interval_min;
> +	__le16 interval_max;
> +	__le16 latency;
> +	__le16 timeout;
> +} __packed;
> +
> /* Advertising report event types */
> #define LE_ADV_IND		0x00
> #define LE_ADV_DIRECT_IND	0x01
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 7a23324..4ded97b 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -4309,6 +4309,52 @@ not_found:
> 	hci_dev_unlock(hdev);
> }
> 
> +static void send_conn_param_neg_reply(struct hci_dev *hdev, u16 handle,
> +				      u8 reason)
> +{
> +	struct hci_cp_le_conn_param_req_neg_reply cp;
> +
> +	cp.handle = cpu_to_le16(handle);
> +	cp.reason = reason;
> +
> +	hci_send_cmd(hdev, HCI_OP_LE_CONN_PARAM_REQ_NEG_REPLY, sizeof(cp),
> +		     &cp);
> +}
> +
> +static void hci_le_remote_conn_param_req_evt(struct hci_dev *hdev,
> +					     struct sk_buff *skb)
> +{
> +	struct hci_ev_le_remote_conn_param_req *ev = (void *) skb->data;
> +	struct hci_cp_le_conn_param_req_reply cp;
> +	struct hci_conn *hcon;
> +	u16 handle, min, max, latency, timeout;
> +
> +	handle = le16_to_cpu(ev->handle);
> +	min = le16_to_cpu(ev->interval_min);
> +	max = le16_to_cpu(ev->interval_max);
> +	latency = le16_to_cpu(ev->latency);
> +	timeout = le16_to_cpu(ev->timeout);
> +
> +	hcon = hci_conn_hash_lookup_handle(hdev, handle);
> +	if (!hcon || hcon->state != BT_CONNECTED)
> +		return send_conn_param_neg_reply(hdev, handle,
> +						 HCI_ERROR_UNKNOWN_CONN_ID);
> +
> +	if (hci_check_conn_params(min, max, latency, timeout))
> +		return send_conn_param_neg_reply(hdev, handle,
> +						 HCI_ERROR_INVALID_LL_PARAMS);
> +
> +	cp.handle = ev->handle;
> +	cp.interval_min = ev->interval_min;
> +	cp.interval_max = ev->interval_max;
> +	cp.latency = ev->latency;
> +	cp.timeout = ev->timeout;
> +	cp.min_ce_len = 0;
> +	cp.max_ce_len = 0;
> +
> +	hci_send_cmd(hdev, HCI_OP_LE_CONN_PARAM_REQ_REPLY, sizeof(cp), &cp);
> +}
> +
> static void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
> {
> 	struct hci_ev_le_meta *le_ev = (void *) skb->data;
> @@ -4332,6 +4378,10 @@ static void hci_le_meta_evt(struct hci_dev *hdev, struct sk_buff *skb)
> 		hci_le_ltk_request_evt(hdev, skb);
> 		break;
> 
> +	case HCI_EV_LE_REMOTE_CONN_PARAM_REQ:
> +		hci_le_remote_conn_param_req_evt(hdev, skb);
> +		break;
> +

you also need a patch that will enable this event.

Regards

Marcel