Re: [PATCH 1/2] rust: usb: add basic USB abstractions

[Daniel Almeida <daniel.almeida@collabora.com>]

Hi Danilo,


>> +/// A USB device.
>> +///
>> +/// This structure represents the Rust abstraction for a C [`struct usb_device`].
>> +/// The implementation abstracts the usage of a C [`struct usb_device`] passed in
>> +/// from the C side.
>> +///
>> +/// # Invariants
>> +///
>> +/// A [`Device`] instance represents a valid [`struct usb_device`] created by the C portion of the
>> +/// kernel.
>> +///
>> +/// [`struct usb_device`]: https://www.kernel.org/doc/html/latest/driver-api/usb/usb.html#c.usb_device
>> +#[repr(transparent)]
>> +pub struct Device<Ctx: device::DeviceContext = device::Normal>(
>> +    Opaque<bindings::usb_device>,
>> +    PhantomData<Ctx>,
>> +);
> 
> What do you use the struct usb_device abstraction for? I only see the sample
> driver probing a USB interface instead.

What I was brainstorming with Greg is to submit this initial support, and then
follow up with all the other abstractions needed to implement a Rust version of
usb-skeleton.c. IIUC, the plan is to submit any fixes as follow-ups, as we're
close to the merge window.

struct usb_device would be used for the skeleton driver, so we should keep it if
we're following the plan above, IMHO.

— Daniel