[PATCH v2] Bluetooth: btusb: Add Realtek RTL8852BE BT 0x04c5/0x1670 (Fujitsu)

[Jaroslav Srba <jarys.cz@gmail.com>]

The Fujitsu LIFEBOOK E5512A ships with a Realtek RTL8852BE combo chip
whose Bluetooth half is exposed as a Fujitsu-rebranded USB device
0x04c5/0x1670. Without this entry in quirks_table, btusb binds via the
generic Bluetooth class match but never sets the BTUSB_REALTEK quirk,
so btrtl_setup_realtek() is never called and the rtl8852bu firmware
patch is never loaded. As a result HCI works (hci0 UP RUNNING), but
RF reception is non-functional: inquiry and LE scan find nothing and
pairing is impossible.

Other Fujitsu OEM rebrands of Realtek chips are already in quirks_table
(0x04c5/0x165c, 0x04c5/0x1675, 0x04c5/0x161f). Add 0x04c5/0x1670 in
the same "Realtek 8852BE Bluetooth devices" block, alongside 0x04c5/0x165c.

USB descriptors of the device:

    Bus 001 Device 004: ID 04c5:1670 Fujitsu, Ltd Bluetooth Radio
      bDeviceClass          224 Wireless
      bDeviceSubClass         1 Radio Frequency
      bDeviceProtocol         1 Bluetooth
      iManufacturer           1 Realtek
      iProduct                2 Bluetooth Radio

Tested on Fujitsu LIFEBOOK E5512A (Ryzen 7 PRO 5875U, Ubuntu 25.10,
kernel 6.17.0-29-generic). After the patch:

  Bluetooth: hci0: RTL: rom_version status=0 version=1
  Bluetooth: hci0: RTL: loading rtl_bt/rtl8852bu_fw.bin
  Bluetooth: hci0: RTL: loading rtl_bt/rtl8852bu_config.bin
  Bluetooth: hci0: RTL: fw version 0x098b154b
  Bluetooth: hci0: AOSP extensions version v1.00

Scanning, pairing and A2DP audio playback to BT headphones all work
after the firmware patch is loaded.

Signed-off-by: Jaroslav Srba <jarys.cz@gmail.com>
---
Changes in v2:
 - Drop a long "RTL: examining hci_ver=..." line from the commit body
   to satisfy checkpatch/gitlint 75-char limit. Chip identification is
   conveyed by the firmware filename (rtl8852bu_fw.bin) and the
   subsequent rom_version line, so no information is lost.

 drivers/bluetooth/btusb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 7f5fce93d..93fcc02e0 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -543,6 +543,8 @@ static const struct usb_device_id quirks_table[] = {
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x04c5, 0x165c), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },
+	{ USB_DEVICE(0x04c5, 0x1670), .driver_info = BTUSB_REALTEK |
+						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x04ca, 0x4006), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x0cb8, 0xc549), .driver_info = BTUSB_REALTEK |
-- 
2.51.0