Broadcom Bluetooth

Broadcom Article description::Bluetooth 4.x devices mostly based on BCM20702, BCM4354, BCM4356 chipsets and used in various devices including USB-dongles, hybrid WIFI+Bluetooth embedded chipsets and such.

Hardware
Mostly complete list of supported devices: https://github.com/winterheart/broadcom-bt-firmware/blob/master/DEVICES.md

Security Considerations
Recently several vulnerabilities have been discovered in the Bluetooth stack such as CVE-2018-5383, CVE-2019-9506 (KNOB), CVE-2020-10135 (BIAS) and more. Since Broadcom has stopped active support for its consumer devices, your system may be subject to security risks. You will have to use these devices at your own risk. The repository maintainer can't provide security fixes.

Firmware
Mostly Broadcom Bluetooth stack requires external firmware, supplied with Windows drivers. You can check this by using following commands:

Luckily, you can use package which install most recent firmware files for Broadcom Bluetooth:

After installing you need to reinsert Bluetooth device or reboot system for applying firmware. After that your output should looks like that:

Configuration
After enabling kernel options and installing firmware, you should proceed to Bluetooth manual.

Kernel requires BCM.hcd or BCM.hcd
Some VID/PIDs not yet defined in kernel driver so btbcm cannot properly identify your device:

In this case you need to retrieve VID/PID manually via or  command:

Here your VID/PID -. Next, check Devices list and choose your firmware. After that just copy firmware file into name that requires kernel:

After that reinsert device or reboot system.

After installing firmware device still won't work
Some Bluetooth controller (for example, BCM4354 and BCM4356) are integrated to WiFi chipset (this can be BCM43XX 802.11ac Wireless Network Adapter or just simple generic Broadcom PCIE Wireless). These devices requires two kinds of firmware - first for WiFi, and second for Bluetooth. Without WiFi firmware Bluetooth will not initialize and will not work properly. Firmware for WiFi already included to kernel, but you may need to do additional work to place correct NVRAM.

Here example how it can looks (note about loading - this is your customized NVRAM):