Module usbdev 

A USB host’s report to the supervisor about a device it does not drive itself, so the supervisor can start that device’s driver when it arrives and stop it when it leaves (docs/usb-device-drivers.md).

The host reports FACTS - present or not, VID:PID, how many times it has bound one - and never names a driver: which driver a device gets is the supervisor’s table. Sent with try_send and never answered, so a host never waits on the supervisor (8.9). Each report is the host’s whole state for that device, not a change, so a duplicate is harmless and a lost one is corrected by the next.

Structs

Report

One report. gen counts every bind on that host, so the same dongle bound again - a replug, or the host re-enumerating it - reads differently from the same dongle still bound.

Constants

ASK

Supervisor to host, one byte and no reply capability: send your report again. How a respawned supervisor learns what is attached (6.2). In the host’s request space beside usbfn’s ops (0x20 up), clear of them and of every block and net op.

HOSTS

How many host numbers there are: a table indexed by one is this long.

HOST_DWC2

Which host a report is from: a PC has two that bind a device for a driver of its own, xhci and ehci, and each reports only what IT has bound - so “nothing attached” from one says nothing of the other’s.

HOST_EHCI

HOST_XHCI

LEN

REPORT

The report’s opcode, after supcmd::MARKER: [MARKER, REPORT, present, gen(4 LE), vid(2 LE), pid(2 LE), host].

Functions

decode

None for anything that is not exactly a report.

encode

host_name

The service a host number names, or None for a number that is not one.