> On 9 Mar 2025, at 2:24 PM, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > On Sun, Mar 09, 2025 at 08:40:31AM +0000, Aditya Garg wrote: >> From: Paul Pawlowski <paul@xxxxxxxx> >> >> This patch adds a driver named apple-bce, to add support for the T2 >> Security Chip found on certain Macs. >> >> The driver has 3 main components: >> >> BCE (Buffer Copy Engine) - this is what the files in the root directory >> are for. This estabilishes a basic communication channel with the T2. >> VHCI and Audio both require this component. > > So this is a new "bus" type? Or a platform resource? Or something > else? It's a PCI device > >> VHCI - this is a virtual USB host controller; keyboard, mouse and >> other system components are provided by this component (other >> drivers use this host controller to provide more functionality). > > I don't understand, why does a security chip have a USB virtual > interface in it? What "devices" hang off of it that are found and > enumerated by the host OS? The t2 chip not only handles security, but also has a usb hub, which connects the internal keyboard, trackpad, touchbar, webcam, and other internal devices. The external usb ports are separate. > > And what other drivers use this controller, just normal Linux drivers, > or vendor-specific ones? The already upstream drivers like hid-Apple etc will use this, basically depending upon what usb device is exposed. > >> Audio - a driver for the T2 audio interface, currently only audio >> output is supported. > > Again, is this a platform device or does it sit on the BCE "bus" you > will create here? Again, audio video encoders are also a part of this chip. You can say this chip is more of a co processor. > > thanks, > > greg k-h
