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The USB abstractions target to support USB interface drivers.
While internally the abstraction has to deal with the interface's parent
USB device, there shouldn't be a need for users to deal with the parent
USB device directly.
Functions, such as for preparing and sending USB URBs, can be
implemented for the usb::Interface structure directly. Whether this
internal implementation has to deal with the parent USB device can
remain transparent to USB interface drivers.
Hence, keep the usb::Device structure private for now, in order to avoid
confusion for users and to make it less likely to accidentally expose
APIs with unnecessary indirections.
Should we start supporting USB device drivers, or need it for any other
reason we do not foresee yet, it should be trivial to make it public
again.
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250925190400.144699-2-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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When deriving the parent USB device (struct usb_device) from a USB
interface (struct usb_interface), do not retain the device context.
For the Bound context, as pointed out by Alan in [1], it is not
guaranteed that the parent USB device is always bound when the interface
is bound.
The bigger problem, however, is that we can't infer the Core context,
since eventually it indicates that the device lock is held. However,
there is no guarantee that if the device lock of the interface is held,
also the device lock of the parent USB device is held.
Hence, fix this by not inferring any device context information; while
at it, fix up the (affected) safety comments.
Link: https://lore.kernel.org/all/0ff2a825-1115-426a-a6f9-df544cd0c5fc@rowland.harvard.edu/ [1]
Fixes: e7e2296b0ecf ("rust: usb: add basic USB abstractions")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250925190400.144699-1-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add basic USB abstractions, consisting of usb::{Device, Interface,
Driver, Adapter, DeviceId} and the module_usb_driver macro. This is the
first step in being able to write USB device drivers, which paves the
way for USB media drivers - for example - among others.
This initial support will then be used by a subsequent sample driver,
which constitutes the only user of the USB abstractions so far.
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://lore.kernel.org/r/20250825-b4-usb-v1-1-7aa024de7ae8@collabora.com
[ force USB = y for now - gregkh ]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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