Re: [libusb] USB Keyboard driver for new OS

[Tim R. <ti...@pr...>]

David Grayson wrote:
> libusb is meant to be run in user space, not the kernel.  It uses 
> system calls to talk to the kernel and tell the kernel what kind of 
> I/O it wants to perform on the USB devices connected to the system.  
> The kernel needs to have its own sophisticated USB drivers in order to 
> handle those requests from libusb.  It would take those requests and 
> figure out how to pass them on to the USB controller devices in your 
> computer.  I don't know much about the lower-level interfaces used by 
> USB controllers, but I've heard keywords like UHCI and XHCI.

This is good advice.  If you want your operating system to be more than 
a toy, then you will have to have host controller drivers: EHCI for USB 
2, and XHCI for USB 3.  They are complicated, but there are a few 
samples on the internet.  Above that, you need a USB hub driver to 
manage collections of devices. Above that, you put drivers for the 
various pre-defined device classes, like HID (mouse and keyboard), 
storage (for USB disks), audio, video, etc.

HOWEVER, if this is just a toy for you to play with, USB HID devices 
have a special "boot mode" that allow them to operate in a much simpler 
environment.  That's how your BIOS can understand your keyboard and 
mouse.  The BIOS does not have a full USB stack by any means.

-- 
Tim Roberts, ti...@pr...
Providenza & Boekelheide, Inc.