svc.usbd¶

USB hotplug daemon that polls for USB port changes once per second.

Overview¶

svc.usbd spawns a single usbd preemptive process that calls driver.bus.usb.core.usb_check_hotplug on each iteration and then sleeps for approximately one second using proc.mgr.proc_sleep_ms. This provides ongoing detection of USB device connection and disconnection events without dedicating an interrupt to the task.

The daemon runs at priority 2, giving it a quantum of 10 ticks, which is sufficient for the low-frequency polling workload.

Dependencies¶

driver.bus.usb.core
proc.mgr
proc.types
io.syslog

Functions and Procedures¶

init¶

procedure init;

Creates the usbd process at priority 2 with usbd_loop as its entry point and logs a confirmation via io.syslog.

usbd_loop (internal)¶

procedure usbd_loop(ctx: PProcessContext);

Process entry point. Loops indefinitely, calling driver.bus.usb.core.usb_check_hotplug and then sleeping for 1000 ms via proc.mgr.proc_sleep_ms(1000).

Notes¶

proc_sleep_ms(1000) translates to approximately 1024 BDA ticks at the 1024 Hz tick rate, so the actual polling interval is close to but not exactly one second.

The loop does not check for smTerminate; the usbd process can be stopped by calling proc.mgr.kill with its PID.