Repurpose usb crate name for something useful

[kevinmehall]

This obsolete library is sitting on a valuable crate name. We should repurpose it to create some common USB types, constants and traits that can be used across USB host and device implementations in Rust to improve interoperability, kind of like the http crate does for HTTP servers and clients.

Descriptors

These should be constructed by const fn and store their data in wire format so they can be constructed in flash as a static and used directly in DMA on devices that support this.

• Device
• Configuration
• Interface
• Endpoint
• String
• BOS
• HID, CDC, etc (or should classes go in a separate crate?)
• setup packets

Constants

• bDeviceClass codes
• Endpoint types
• Standard control transfer requests

Traits for USB IO?

Not sure if these should be defined before async is usable in traits and on no_std.

[NickAtAccuPS]

• HID, CDC, etc (or should classes go in a separate crate?)

Probably best as a separate crate at least for HID, given that HID is abstracted over several buses.

[kevinmehall]

@japaric I noticed you're working on something like this at https://github.com/japaric/usb2 and would be happy to give you the usb name on crates.io for it.