The SET_LINE_CODING request contains data and must be
handled as such.
Previously, the only requests that had data were IN
requests. SET_LINE_CODING is an OUT request so it
required additional changes to support a new type of
data request.
The CDC interface is always advertised in the FW USB
descriptors. It is NOT always enabled/initialized at
runtime. Specifically, it can be Disabled in HwSettings.
Previously, any CDC-related query that the host would send
resulted in an assert and a watchdog.
Now, a suitable return code indicating that the request is
unsupported is returned in this scenario.
Summary of changes:
* USB CDC and HID drivers are completely split apart.
* This will allow different max buffer sizes for HID and CDC.
* USB descriptors have been overhauled:
* Proper structs/macros/enums declared for USB (see pios_usb_defs.h)
* Two common descriptor definitions. One for HID+CDC another for HID only.
See pios_usb_desc_{hid_cdc,hid_only}.c for details.
* Long standing bugs in OP USB descriptors became much more obvious with the
new struct definitions.
* Board specific USB initialization is now in pios_usb_board_data.h in each build target.
* Definition of USB descriptors is now entirely indpendent of STM32 libs.
Glue into STM32 libs is provided by pios_usbhook.c.
* Removed a lot of stale/irrelevant USB #defines throughout the tree.
* Improved naming consistency throughout USB code:
* PIOS_USB_HID_* now refers to the HID endpoint code.
* PIOS_USB_CDC_* now refers to the CDC endpoint code.
* PIOS_USB_* now refers to the low-level USB code.
* PIOS_USB_BOARD_* now refers to board-specific USB data
* PIOS_USBHOOK_* is glue between PIOS and STM32 USB libs.
* struct usb_* and enum usb_* and USB_* and HID_* are all types from the USB spec.
* Shrunk the buffer size on the CDC call mgmt endpoint to save some RAM.
* Made a few more USB related variables static to save some RAM.
