danukeru authored Aug 24, 2019 and Rahix committed Aug 24, 2019

Previously, race-conditions between multiple serial writes could lead to
memory corruption and weird artifacts like I2C getting stuck.  This
patch introduces a write-streambuffer which queues all messages.

Co-authored-by: Rahix <rahix@rahix.de>
Signed-off-by: danukeru <danukeru@foulab.org>

swym authored Aug 24, 2019 and Rahix committed Aug 24, 2019

usb/epc_usb
====
Contains device-independent USB implementation, services MAXUSB stack
and is given the actual USB descriptors & callbacks on initialization.
Handles USB events and configures/deconfigures the device accordingly
during the USB setup procedure.

usb/mass_storage & cdcacm
====
Contain device-specific implementations, service MAXUSB's device class
APIs for cdcacm and mass storage.
Here, mass storage is independent of the underlying storage device.

modules/usb
====
Public apic_usb API, configuration and storage device management.
Defines the actual USB device descriptors and services the upc_usb API.

If we want to add SD card functionality, this would be the place to add
it.