HID: add support for Huion 580 tablet

Add hid-huion.c with support for Huion 580 tablet, which is simple
8x5" tablet with 4000LPI resolution and 2048 levels pressure-sensitive
pen manufactured by the Chinese company Huion.

The driver fixes incorrect report descriptor sent by the device,
performs custom initialization required to switch the tablet into
its native resolution mode and inverts the in-range bit.

Signed-off-by: Martin Rusko <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/Kconfig

···
 	  Say Y here if you have a Holtek On Line Grip based game controller
 	  and want to have force feedback support for it.
 
+config HID_HUION
+	tristate "Huion tablets"
+	depends on USB_HID
+	---help---
+	Support for Huion 580 tablet.
+
 config HID_KEYTOUCH
 	tristate "Keytouch HID devices"
 	depends on HID

drivers/hid/Makefile

···
 obj-$(CONFIG_HID_GYRATION)	+= hid-gyration.o
 obj-$(CONFIG_HID_HOLTEK)	+= hid-holtek-kbd.o
 obj-$(CONFIG_HID_HOLTEK)	+= hid-holtekff.o
+obj-$(CONFIG_HID_HUION)		+= hid-huion.o
 obj-$(CONFIG_HID_HYPERV_MOUSE)	+= hid-hyperv.o
 obj-$(CONFIG_HID_ICADE)		+= hid-icade.o
 obj-$(CONFIG_HID_KENSINGTON)	+= hid-kensington.o

drivers/hid/hid-core.c

···
 	{ HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE_3) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK, USB_DEVICE_ID_HOLTEK_ON_LINE_GRIP) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT, USB_DEVICE_ID_HOLTEK_ALT_KEYBOARD) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HUION, USB_DEVICE_ID_HUION_580) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_JESS2, USB_DEVICE_ID_JESS2_COLOR_RUMBLE_PAD) },
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ION, USB_DEVICE_ID_ICADE) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_KENSINGTON, USB_DEVICE_ID_KS_SLIMBLADE) },

drivers/hid/hid-huion.c

···
+/*
+ *  HID driver for Huion devices not fully compliant with HID standard
+ *
+ *  Copyright (c) 2013 Martin Rusko
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include "usbhid/usbhid.h"
+
+#include "hid-ids.h"
+
+/* Original Huion 580 report descriptor size */
+#define HUION_580_RDESC_ORIG_SIZE	177
+
+/* Fixed Huion 580 report descriptor */
+static __u8 huion_580_rdesc_fixed[] = {
+	0x05, 0x0D,         /*  Usage Page (Digitizer),             */
+	0x09, 0x02,         /*  Usage (Pen),                        */
+	0xA1, 0x01,         /*  Collection (Application),           */
+	0x85, 0x07,         /*      Report ID (7),                  */
+	0x09, 0x20,         /*      Usage (Stylus),                 */
+	0xA0,               /*      Collection (Physical),          */
+	0x14,               /*          Logical Minimum (0),        */
+	0x25, 0x01,         /*          Logical Maximum (1),        */
+	0x75, 0x01,         /*          Report Size (1),            */
+	0x09, 0x42,         /*          Usage (Tip Switch),         */
+	0x09, 0x44,         /*          Usage (Barrel Switch),      */
+	0x09, 0x46,         /*          Usage (Tablet Pick),        */
+	0x95, 0x03,         /*          Report Count (3),           */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0x95, 0x03,         /*          Report Count (3),           */
+	0x81, 0x03,         /*          Input (Constant, Variable), */
+	0x09, 0x32,         /*          Usage (In Range),           */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x03,         /*          Input (Constant, Variable), */
+	0x75, 0x10,         /*          Report Size (16),           */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0xA4,               /*          Push,                       */
+	0x05, 0x01,         /*          Usage Page (Desktop),       */
+	0x65, 0x13,         /*          Unit (Inch),                */
+	0x55, 0xFD,         /*          Unit Exponent (-3),         */
+	0x34,               /*          Physical Minimum (0),       */
+	0x09, 0x30,         /*          Usage (X),                  */
+	0x46, 0x40, 0x1F,   /*          Physical Maximum (8000),    */
+	0x26, 0x00, 0x7D,   /*          Logical Maximum (32000),    */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0x09, 0x31,         /*          Usage (Y),                  */
+	0x46, 0x88, 0x13,   /*          Physical Maximum (5000),    */
+	0x26, 0x20, 0x4E,   /*          Logical Maximum (20000),    */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0xB4,               /*          Pop,                        */
+	0x09, 0x30,         /*          Usage (Tip Pressure),       */
+	0x26, 0xFF, 0x07,   /*          Logical Maximum (2047),     */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0xC0,               /*      End Collection,                 */
+	0xC0                /*  End Collection                      */
+};
+
+static __u8 *huion_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	switch (hdev->product) {
+	case USB_DEVICE_ID_HUION_580:
+		if (*rsize == HUION_580_RDESC_ORIG_SIZE) {
+			rdesc = huion_580_rdesc_fixed;
+			*rsize = sizeof(huion_580_rdesc_fixed);
+		}
+		break;
+	}
+	return rdesc;
+}
+
+/**
+ * Enable fully-functional tablet mode by reading special string
+ * descriptor.
+ *
+ * @hdev:	HID device
+ *
+ * The specific string descriptor and data were discovered by sniffing
+ * the Windows driver traffic.
+ */
+static int huion_tablet_enable(struct hid_device *hdev)
+{
+	int rc;
+	char buf[22];
+
+	rc = usb_string(hid_to_usb_dev(hdev), 0x64, buf, sizeof(buf));
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+static int huion_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+
+	/* Ignore interfaces 1 (mouse) and 2 (keyboard) for Huion 580 tablet,
+	 * as they are not used
+	 */
+	switch (id->product) {
+	case USB_DEVICE_ID_HUION_580:
+		if (intf->cur_altsetting->desc.bInterfaceNumber != 0x00)
+			return -ENODEV;
+		break;
+	}
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		goto err;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		goto err;
+	}
+
+	switch (id->product) {
+	case USB_DEVICE_ID_HUION_580:
+		ret = huion_tablet_enable(hdev);
+		if (ret) {
+			hid_err(hdev, "tablet enabling failed\n");
+			goto enabling_err;
+		}
+		break;
+	}
+
+	return 0;
+enabling_err:
+	hid_hw_stop(hdev);
+err:
+	return ret;
+}
+
+static int huion_raw_event(struct hid_device *hdev, struct hid_report *report,
+			u8 *data, int size)
+{
+	/* If this is a pen input report then invert the in-range bit */
+	if (report->type == HID_INPUT_REPORT && report->id == 0x07 && size >= 2)
+		data[1] ^= 0x40;
+
+	return 0;
+}
+
+static const struct hid_device_id huion_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HUION, USB_DEVICE_ID_HUION_580) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, huion_devices);
+
+static struct hid_driver huion_driver = {
+	.name = "huion",
+	.id_table = huion_devices,
+	.probe = huion_probe,
+	.report_fixup = huion_report_fixup,
+	.raw_event = huion_raw_event,
+};
+module_hid_driver(huion_driver);
+
+MODULE_AUTHOR("Martin Rusko");
+MODULE_DESCRIPTION("Huion HID driver");
+MODULE_LICENSE("GPL");

drivers/hid/hid-ids.h

···
 #define USB_DEVICE_ID_UGCI_FLYING	0x0020
 #define USB_DEVICE_ID_UGCI_FIGHTING	0x0030
 
+#define USB_VENDOR_ID_HUION		0x256c
+#define USB_DEVICE_ID_HUION_580		0x006e
+
 #define USB_VENDOR_ID_IDEACOM		0x1cb6
 #define USB_DEVICE_ID_IDEACOM_IDC6650	0x6650
 #define USB_DEVICE_ID_IDEACOM_IDC6651	0x6651