When the firmware hang or command no response, driver can reset the
bluetooth mcu via USB to recovery it. The reset steps as follows.

1. Cancel USB transfer requests before reset.
2. It use speicific USB HW Register to reset Bluetooth MCU, at the
  same time, the USB Endpoint0 still keep alive.
3. Poll the USB HW register until reset is completed by Endpoint0.
4. To recovery unexpected USB state and behavior during resetting the
  Bluetooth MCU, the driver need to reset the USB device for MT7921.
5. After the reset is completed, the Bluetooth MCU need to re-setup,
  such as download patch, power-on sequence and etc.

Signed-off-by: mark-yw.chen <redacted>
---
drivers/bluetooth/btusb.c | 127 ++++++++++++++++++++++++++++++++++++++
1 file changed, 127 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index b1249b664981..122a928ebcb5 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c

@@ -3076,6 +3076,17 @@ static int btusb_shutdown_intel_new(struct hci_dev *hdev)

	return 0;
}

+/* UHW CR mapping */
+#define BT_MISC			0x70002510
+#define BT_SUBSYS_RST		0x70002610
+#define UDMA_INT_STA_BT		0x74000024
+#define UDMA_INT_STA_BT1	0x74000308
+#define BT_WDT_STATUS		0x740003A0
+#define EP_RST_OPT		0x74011890
+#define EP_RST_IN_OUT_OPT	0x00010001
+#define BT_RST_DONE		0x00000100
+#define BT_RESET_WAIT_MS	100
+#define BT_RESET_NUM_TRIES	10