Tried snooping around mailing lists and forums for the past couple of days but seems this is a fairly new thing.
One thing I've managed get back is the hci0 device, I've had to (re)start (enable it also, if disabled) the
brcm43438.service that actually executes:
/usr/bin/btattach -B /dev/ttyAMA0 -P bcm -S 3000000
This service file is in the pi-bluetooth package which -- misleadingly -- advertises itself as something for the rPi 3...
But even though I now have the bluetooth device created:
$ ls -la /sys/class/bluetooth/
drwxr-xr-x 2 root root 0 2020-06-22 20:40:10 ./
drwxr-xr-x 62 root root 0 2020-06-21 21:48:01 ../
lrwxrwxrwx 1 root root 0 2020-06-22 20:40:10 hci0 -> ../../devices/platform/soc/fe201000.serial/tty/ttyAMA0/hci0/
I still can't get bluetoothd (from bluez) to recognize the adapter:
$ bluetoothctl show
No default controller available
Can you check if you have anything under /sys/class/bluetooth?
Also, do you have something like this in your /boot/config.txt:
And do you have something along these lines in your dmesg output?
Bluetooth: hci0: command 0x1001 tx timeout
Bluetooth: hci0: BCM: Reading local version info failed (-110)