Bluetooth: Add support for utilizing Fast Advertising Interval

Changes made to add support for fast advertising interval
as per core 4.1 specification, section 9.3.11.2.

A peripheral device entering any of the following GAP modes and
sending either non-connectable advertising events or scannable
undirected advertising events should use adv_fast_interval2
(100ms - 150ms) for adv_fast_period(30s).

- Non-Discoverable Mode
- Non-Connectable Mode
- Limited Discoverable Mode
- General Discoverable Mode

Signed-off-by: Spoorthi Ravishankar Koppad <[e-mail]>
Signed-off-by: Marcel Holtmann <[e-mail]>

include/net/bluetooth/hci_core.h

···
 #define DISCOV_INTERLEAVED_INQUIRY_LEN	0x04
 #define DISCOV_BREDR_INQUIRY_LEN	0x08
 #define DISCOV_LE_RESTART_DELAY		msecs_to_jiffies(200)	/* msec */
+#define DISCOV_LE_FAST_ADV_INT_MIN     100     /* msec */
+#define DISCOV_LE_FAST_ADV_INT_MAX     150     /* msec */
 
 void mgmt_fill_version_info(void *ver);
 int mgmt_new_settings(struct hci_dev *hdev);

net/bluetooth/hci_request.c

···
 	struct hci_cp_le_set_adv_param cp;
 	u8 own_addr_type, enable = 0x01;
 	bool connectable;
+	u16 adv_min_interval, adv_max_interval;
 	u32 flags;
 
 	flags = get_adv_instance_flags(hdev, hdev->cur_adv_instance);
···
 		return;
 
 	memset(&cp, 0, sizeof(cp));
-	cp.min_interval = cpu_to_le16(hdev->le_adv_min_interval);
-	cp.max_interval = cpu_to_le16(hdev->le_adv_max_interval);
 
-	if (connectable)
+	if (connectable) {
 		cp.type = LE_ADV_IND;
-	else if (get_cur_adv_instance_scan_rsp_len(hdev))
-		cp.type = LE_ADV_SCAN_IND;
-	else
-		cp.type = LE_ADV_NONCONN_IND;
 
+		adv_min_interval = hdev->le_adv_min_interval;
+		adv_max_interval = hdev->le_adv_max_interval;
+	} else {
+		if (get_cur_adv_instance_scan_rsp_len(hdev))
+			cp.type = LE_ADV_SCAN_IND;
+		else
+			cp.type = LE_ADV_NONCONN_IND;
+
+		if (!hci_dev_test_flag(hdev, HCI_DISCOVERABLE) ||
+		    hci_dev_test_flag(hdev, HCI_LIMITED_DISCOVERABLE)) {
+			adv_min_interval = DISCOV_LE_FAST_ADV_INT_MIN;
+			adv_max_interval = DISCOV_LE_FAST_ADV_INT_MAX;
+		} else {
+			adv_min_interval = hdev->le_adv_min_interval;
+			adv_max_interval = hdev->le_adv_max_interval;
+		}
+	}
+
+	cp.min_interval = cpu_to_le16(adv_min_interval);
+	cp.max_interval = cpu_to_le16(adv_max_interval);
 	cp.own_address_type = own_addr_type;
 	cp.channel_map = hdev->le_adv_channel_map;