Man page 9 : usb_get_status

usb_get_status - issues a GET_STATUS call

int usb_get_status(struct usb_device *  dev , int  type , int  target , void *  data );

dev
    the device whose status is being checked

type
    USB_RECIP_*; for device, interface, or endpoint

target
    zero (for device), else interface or endpoint number

data
    pointer to two bytes of bitmap data

!in_interrupt ()

Returns device, interface, or endpoint status. Normally only of interest to see if the device is self powered, or has enabled the remote wakeup facility; or whether a bulk or interrupt endpoint is halted (« stalled »).

Bits in these status bitmaps are set using the SET_FEATURE request, and cleared using the CLEAR_FEATURE request. The usb_clear_halt function should be used to clear halt (« stall ») status.

This call is synchronous, and may not be used in an interrupt context.

Returns the number of bytes received on success, or else the status code returned by the underlying usb_control_msg call.