Re: HID gadget driver supports get/set features ?

[Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>]

Ranran <ranshalit@xxxxxxxxx> writes:

> Hello,
>
> From my reading about HID gadget driver (hidg), it seems that it
> support input reports, but not get/set features.
> This is my understanding from the documentation:
> https://www.kernel.org/doc/Documentation/usb/gadget_hid.txt
>
> Is that correct ?

you might wanna read the actual implementation, instead. If you're keen,
please update the documentation where it's lacking.

static int hidg_setup(struct usb_function *f,
		const struct usb_ctrlrequest *ctrl)
{
	struct f_hidg			*hidg = func_to_hidg(f);
	struct usb_composite_dev	*cdev = f->config->cdev;
	struct usb_request		*req  = cdev->req;
	int status = 0;
	__u16 value, length;

	value	= __le16_to_cpu(ctrl->wValue);
	length	= __le16_to_cpu(ctrl->wLength);

	VDBG(cdev,
	     "%s crtl_request : bRequestType:0x%x bRequest:0x%x Value:0x%x\n",
	     __func__, ctrl->bRequestType, ctrl->bRequest, value);

	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
		  | HID_REQ_GET_REPORT):
		VDBG(cdev, "get_report\n");

		/* send an empty report */
		length = min_t(unsigned, length, hidg->report_length);
		memset(req->buf, 0x0, length);

		goto respond;
		break;

	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
		  | HID_REQ_GET_PROTOCOL):
		VDBG(cdev, "get_protocol\n");
		length = min_t(unsigned int, length, 1);
		((u8 *) req->buf)[0] = hidg->protocol;
		goto respond;
		break;

	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
		  | HID_REQ_SET_REPORT):
		VDBG(cdev, "set_report | wLength=%d\n", ctrl->wLength);
		goto stall;
		break;

	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
		  | HID_REQ_SET_PROTOCOL):
		VDBG(cdev, "set_protocol\n");
		if (value > HID_REPORT_PROTOCOL)
			goto stall;
		length = 0;
		/*
		 * We assume that programs implementing the Boot protocol
		 * are also compatible with the Report Protocol
		 */
		if (hidg->bInterfaceSubClass == USB_INTERFACE_SUBCLASS_BOOT) {
			hidg->protocol = value;
			goto respond;
		}
		goto stall;
		break;

	case ((USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_INTERFACE) << 8
		  | USB_REQ_GET_DESCRIPTOR):
		switch (value >> 8) {
		case HID_DT_HID:
		{
			struct hid_descriptor hidg_desc_copy = hidg_desc;

			VDBG(cdev, "USB_REQ_GET_DESCRIPTOR: HID\n");
			hidg_desc_copy.desc[0].bDescriptorType = HID_DT_REPORT;
			hidg_desc_copy.desc[0].wDescriptorLength =
				cpu_to_le16(hidg->report_desc_length);

			length = min_t(unsigned short, length,
						   hidg_desc_copy.bLength);
			memcpy(req->buf, &hidg_desc_copy, length);
			goto respond;
			break;
		}
		case HID_DT_REPORT:
			VDBG(cdev, "USB_REQ_GET_DESCRIPTOR: REPORT\n");
			length = min_t(unsigned short, length,
						   hidg->report_desc_length);
			memcpy(req->buf, hidg->report_desc, length);
			goto respond;
			break;

		default:
			VDBG(cdev, "Unknown descriptor request 0x%x\n",
				 value >> 8);
			goto stall;
			break;
		}
		break;

	default:
		VDBG(cdev, "Unknown request 0x%x\n",
			 ctrl->bRequest);
		goto stall;
		break;
	}

stall:
	return -EOPNOTSUPP;

respond:
	req->zero = 0;
	req->length = length;
	status = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
	if (status < 0)
		ERROR(cdev, "usb_ep_queue error on ep0 %d\n", value);
	return status;
}

-- 
balbi

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