How to open USB device in user mode via sysfs.
 

I would like to something like:
int fd = open("/sys/bus/usb/devices/5-1/<something>", O_RDWR);
and then use fd for ioctl() calls (submit urbs, etc.)
I was able to do the same on usbfs:
int fd = open("/proc/bus/usb/005/007", O_RDWR);

Now I need to access the USB via sysfs, because not all Linux platforms have usbfs available. I cannot open("/sys/bus/usb/devices/5-1", O_RDWR) because this is a directory :-( What file in this directory should be opened for ioctl() ?
Please help.
Thank you.

So the answer is, that the device must be found in /dev/bus/usb sub-tree and opened here.