Bluetooth: NXP: Add protocol support for NXP Bluetooth chipsets

This adds a driver based on serdev driver for the NXP BT serial protocol
based on running H:4, which can enable the built-in Bluetooth device
inside an NXP BT chip.

This driver has Power Save feature that will put the chip into sleep state
whenever there is no activity for 2000ms, and will be woken up when any
activity is to be initiated over UART.

This driver enables the power save feature by default by sending the vendor
specific commands to the chip during setup.

During setup, the driver checks if a FW is already running on the chip
by waiting for the bootloader signature, and downloads device specific FW
file into the chip over UART if bootloader signature is received..
Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

MAINTAINERS

@@ -23242,6 +23242,7 @@ M:	Amitkumar Karwar <amitkumar.karwar@nxp.com>
 M:	Neeraj Kale <neeraj.sanjaykale@nxp.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-bt.yaml
+F:	drivers/bluetooth/btnxpuart.c
 
 THE REST
 M:	Linus Torvalds <torvalds@linux-foundation.org>

drivers/bluetooth/Kconfig

@@ -465,4 +465,16 @@ config BT_VIRTIO
 	  Say Y here to compile support for HCI over Virtio into the
 	  kernel or say M to compile as a module.
 
+config BT_NXPUART
+	tristate "NXP protocol support"
+	depends on SERIAL_DEV_BUS
+	select CRC32
+	help
+	  NXP is serial driver required for NXP Bluetooth
+	  devices with UART interface.
+
+	  Say Y here to compile support for NXP Bluetooth UART device into
+	  the kernel, or say M here to compile as a module (btnxpuart).
+
+
 endmenu

drivers/bluetooth/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_BT_QCA)		+= btqca.o
 obj-$(CONFIG_BT_MTK)		+= btmtk.o
 
 obj-$(CONFIG_BT_VIRTIO)		+= virtio_bt.o
+obj-$(CONFIG_BT_NXPUART)	+= btnxpuart.o
 
 obj-$(CONFIG_BT_HCIUART_NOKIA)	+= hci_nokia.o