Linux Driver Posted Enabling Bluetooth Support For Apple M1/M2, Some x86 Macs
This Bluetooth "hci_bcm4377" driver posted for review is for enabling the Broadcom BCM4377/4378/4387 controllers as found in the Apple M1/M2 systems and select Apple x86 Macs too.
There are some peculiarities to these Broadcom controllers used by Apple:
Unlike regular Broadcom chips attached over UART or SDIO these no longer support the usual patchram / minidriver firmware loading. Instead the firmware is just directly mapped to the PCIe device and then booted. In general the entire PCIe configuration space is similar to brcmfmac (or the Android downstream bcmdhd driver). There are not many similarities with UART Broadcom devices.
The firmware naming itself is a bit annoying but similar to the WiFi function / brcmfmac: We need the chip id (e.g. 4377), the chip stepping (e.g. b3), the module name (e.g. apple,atlantisb) and the antenna vendor (e.g. m for Murata) to select the correct firmware file.
...
This has been tested by quite a few people on various M1/M2 machines and a few people with x86 T2 machines. So far we only know that WiFi/Bluetooth coexistence is not working yet, but that needs to be configured inside brcmfmac as far as we can tell.
Unfortunately, there isn't an easy means of distributing the necessary firmware for this driver on Linux. Sven noted that currently the Asahi Linux installer extracts it from the macOS image with not being able to redistribute the binary directly, "We unfortunately can't distribute the firmware itself but we can extract it from the official macOS update packages Apple distributes. Our installer for M1/M2 extracts the latest firmware and prepares it for Linux (and BSD) automatically"
This Bluetooth driver for modern Apple Macs is now under review on the kernel mailing list. This new Bluetooth driver comes in at 2.6k lines of code.
Add A Comment
