Bluetooth: btusb: Add routine for applying Intel DDC parameters

This patch adds the routine to apply the DDC parameter from device
specific ddc file.

Once the device is rest to operational mode, optionally, it can
download the device specific configration (DDC) parameters before
the BlueZ starts the stack initialization.

It opens the DDC file based on HW_VARIANT and DEV_REVISION and
send ID/Value with HCI_Intel_Write_DDC command.

Format of DDC file
DDC file contains one or more number of DDC structure.

DDC Structure
It has 'Length' field of one octet, DDC 'ID' field of
two octets followed by the array of DDC 'Value' that gives
the value of parameters itself.
'Length' contains the length of DDC 'ID' and DDC 'Value'.

+------------+----------+
| Size(byte) |    Name  |
+------------+----------+
|      1     | Length   |
+------------+----------+
|      2     | ID       |
+------------+----------+
| Length - 2 | Value    |
+------------+----------+

Signed-off-by: Tedd Ho-Jeong An <tedd.an@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btusb.c

@@ -2083,6 +2083,12 @@ static int btusb_setup_intel_new(struct hci_dev *hdev)
 
 	BT_INFO("%s: Found device firmware: %s", hdev->name, fwname);
 
+	/* Save the DDC file name for later use to apply once the firmware
+	 * downloading is done.
+	 */
+	snprintf(fwname, sizeof(fwname), "intel/ibt-11-%u.ddc",
+		 le16_to_cpu(params->dev_revid));
+
 	kfree_skb(skb);
 
 	if (fw->size < 644) {
@@ -2244,6 +2250,43 @@ done:
 
 	clear_bit(BTUSB_BOOTLOADER, &data->flags);
 
+	/* Once the device is running in operational mode, it needs to apply
+	 * the device configuration (DDC) parameters.
+	 *
+	 * The device can work without DDC parameters, so even if it fails
+	 * to load the file, no need to fail the setup.
+	 */
+	err = request_firmware_direct(&fw, fwname, &hdev->dev);
+	if (err < 0)
+		return 0;
+
+	BT_INFO("%s: Found Intel DDC parameters: %s", hdev->name, fwname);
+
+	fw_ptr = fw->data;
+
+	/* DDC file contains one or more DDC structure which has
+	 * Length (1 byte), DDC ID (2 bytes), and DDC value (Length - 2).
+	 */
+	while (fw->size > fw_ptr - fw->data) {
+		u8 cmd_plen = fw_ptr[0] + sizeof(u8);
+
+		skb = __hci_cmd_sync(hdev, 0xfc8b, cmd_plen, fw_ptr,
+				     HCI_INIT_TIMEOUT);
+		if (IS_ERR(skb)) {
+			BT_ERR("%s: Failed to send Intel_Write_DDC (%ld)",
+			       hdev->name, PTR_ERR(skb));
+			release_firmware(fw);
+			return PTR_ERR(skb);
+		}
+
+		fw_ptr += cmd_plen;
+		kfree_skb(skb);
+	}
+
+	release_firmware(fw);
+
+	BT_INFO("%s: Applying Intel DDC parameters completed", hdev->name);
+
 	return 0;
 }