This commit adds the preliminary version of the USB Host Library. This commit contains:
- USBH (USB Host Driver)
- Hub Driver that only supports a single device and device enumeration
- USB Host Library (asychronous API)
- Test cases for USB Host Library asychronous API
The following changes were made to the existing HCD:
- Removed HCD_PIPE_STATE_INVALID. Pipes are no longer invalidated
- Changed pipe commands to halt, flush, and clear. Pipes need to be manually
halted, flush, and cleared.
- Halting and flushing a pipe will execute the pipe callback if it causes a
HCD_PIPE_EVENT_URB_DONE event
This commit changes the IRP (I/O Request Packet) structure to
the URB (USB Request Block) in order to represent USB transfers
in the host stack. The new URB strcuture:
- Add extra safety with const fields
- Allows each layer of the stack to add their own overhead variables
The HCD layer API and tests have been updated to use this new URB structure
