Writing HID driver

[John Baldwin]

On Wednesday, October 19, 2011 7:56:30 am Alexandr Matveev wrote:
> Hi,
> 
> I'm writing the driver for the USB keyboard, which has two interfaces:
> first is generic keyboard and second is HID device. If I load driver and
> then attach the keyboard - everything is OK. But if I attach keyboard
> and then kldload driver, it won't attach to the device because the default
> uhid driver already attached to it first. To prevent this, driver 
> searches for
> uhid devices after being loaded and compares a pnpinfo string to search
> for suitable devices and detach them.
> 
> Everything works fine, but I have two questions:
> 1) Is there any simpler way to do the same thing?

Not currently, no.

> 2) Is there a way to get device vendor & product without using device
> bus-specific functions?

No, but you can probably implement lkbd_detach_uhid() a bit simpler by doing 
something like:

	devclass_t dc;
	device_t devices;
	int devcount, error, i;

	dc = devclass_find("uhid");
	if (dc == NULL)
		return;
	error = devclass_get_devices(dc, &devices, &devcount);
	if (error) {
		printf("Unable to fetch uhid device list: %d\n", error);
		return;
	}
	for (i = 0; i < devcount; i++) {
		/*
		 * Do the same checks you do in your probe routine and
		 * detach the devices that match.
		 */
	}
	free(devlist, M_TEMP);

-- 
John Baldwin