Re: [PATCH] input: Add support for Wacom protocol 4 serial tablets

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Hans,

On Sat, Jul 19, 2014 at 06:38:40PM +0200, Hans de Goede wrote:
> Recent version of xf86-input-wacom no longer support directly accessing
> serial tablets. Instead xf86-input-wacom now expects all wacom tablets to
> be driven by the kernel and to show up as evdev devices.
> 
> This has caused old serial Wacom tablets to stop working for people who still
> have such tablets. Julian Squires has written a serio input driver to fix this:
> https://github.com/tokenrove/wacom-serial-iv
> 
> This is a cleaned up version of this driver with improved Graphire support
> (I own an old Graphire myself).
> 
> Signed-off-by: Julian Squires <julian@cipht.net>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  MAINTAINERS                          |   7 +
>  drivers/input/tablet/Kconfig         |  12 +
>  drivers/input/tablet/Makefile        |   1 +
>  drivers/input/tablet/wacom_serial4.c | 600 +++++++++++++++++++++++++++++++++++
>  include/uapi/linux/serio.h           |   1 +
>  5 files changed, 621 insertions(+)
>  create mode 100644 drivers/input/tablet/wacom_serial4.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1629ac9..1128b57 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9855,6 +9855,13 @@ M:	Pierre Ossman <pierre@ossman.eu>
>  S:	Maintained
>  F:	drivers/mmc/host/wbsd.*
>  
> +WACOM PROTOCOL 4 SERIAL TABLETS
> +M:	Julian Squires <julian@cipht.net>
> +M:	Hans de Goede <hdegoede@redhat.com>
> +L:	linux-input@vger.kernel.org
> +S:	Maintained
> +F:	drivers/input/tablet/wacom_serial4.c
> +
>  WATCHDOG DEVICE DRIVERS
>  M:	Wim Van Sebroeck <wim@iguana.be>
>  L:	linux-watchdog@vger.kernel.org
> diff --git a/drivers/input/tablet/Kconfig b/drivers/input/tablet/Kconfig
> index bed7cbf..d7c764a 100644
> --- a/drivers/input/tablet/Kconfig
> +++ b/drivers/input/tablet/Kconfig
> @@ -89,4 +89,16 @@ config TABLET_USB_WACOM
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called wacom.
>  
> +config TABLET_SERIAL_WACOM4
> +	tristate "Wacom protocol 4 serial tablet support"
> +	select SERIO
> +	help
> +	  Say Y here if you want to use Wacom protocol 4 serial tablets.
> +	  E.g. serial versions of the Cintiq, Graphire or Penpartner.
> +	  Make sure to say Y to "Mouse support" (CONFIG_INPUT_MOUSEDEV) and/or
> +	  "Event interface support" (CONFIG_INPUT_EVDEV) as well.

Do we really need mousedev for wacom to work?

> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called wacom_serial4.
> +
>  endif
> diff --git a/drivers/input/tablet/Makefile b/drivers/input/tablet/Makefile
> index 3f6c252..4d9339f 100644
> --- a/drivers/input/tablet/Makefile
> +++ b/drivers/input/tablet/Makefile
> @@ -11,3 +11,4 @@ obj-$(CONFIG_TABLET_USB_GTCO)	+= gtco.o
>  obj-$(CONFIG_TABLET_USB_HANWANG) += hanwang.o
>  obj-$(CONFIG_TABLET_USB_KBTAB)	+= kbtab.o
>  obj-$(CONFIG_TABLET_USB_WACOM)	+= wacom.o
> +obj-$(CONFIG_TABLET_SERIAL_WACOM4) += wacom_serial4.o
> diff --git a/drivers/input/tablet/wacom_serial4.c b/drivers/input/tablet/wacom_serial4.c
> new file mode 100644
> index 0000000..587e47c
> --- /dev/null
> +++ b/drivers/input/tablet/wacom_serial4.c
> @@ -0,0 +1,600 @@
> +/*
> + * Wacom protocol 4 serial tablet driver
> + *
> + * Copyright 2014      Hans de Goede <hdegoede@redhat.com>
> + * Copyright 2011-2012 Julian Squires <julian@cipht.net>
> + *
> + * 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 of 2 of the License, or (at your
> + * option) any later version. See the file COPYING in the main directory of
> + * this archive for more details.
> + *
> + * Many thanks to Bill Seremetis, without whom PenPartner support
> + * would not have been possible. Thanks to Patrick Mahoney.
> + *
> + * This driver was developed with reference to much code written by others,
> + * particularly:
> + *  - elo, gunze drivers by Vojtech Pavlik <vojtech@ucw.cz>;
> + *  - wacom_w8001 driver by Jaya Kumar <jayakumar.lkml@gmail.com>;
> + *  - the USB wacom input driver, credited to many people
> + *    (see drivers/input/tablet/wacom.h);
> + *  - new and old versions of linuxwacom / xf86-input-wacom credited to
> + *    Frederic Lepied, France. <Lepied@XFree86.org> and
> + *    Ping Cheng, Wacom. <pingc@wacom.com>;
> + *  - and xf86wacom.c (a presumably ancient version of the linuxwacom code),
> + *    by Frederic Lepied and Raph Levien <raph@gtk.org>.
> + *
> + * To do:
> + *  - support pad buttons; (requires access to a model with pad buttons)
> + *  - support (protocol 4-style) tilt (requires access to a > 1.4 rom model)
> + */
> +
> +/*
> + * Wacom serial protocol 4 documentation taken from linuxwacom-0.9.9 code,
> + * protocol 4 uses 7 or 9 byte of data in the following format:
> + *
> + *	Byte 1
> + *	bit 7  Sync bit always 1
> + *	bit 6  Pointing device detected
> + *	bit 5  Cursor = 0 / Stylus = 1
> + *	bit 4  Reserved
> + *	bit 3  1 if a button on the pointing device has been pressed
> + *	bit 2  P0 (optional)
> + *	bit 1  X15
> + *	bit 0  X14
> + *
> + *	Byte 2
> + *	bit 7  Always 0
> + *	bits 6-0 = X13 - X7
> + *
> + *	Byte 3
> + *	bit 7  Always 0
> + *	bits 6-0 = X6 - X0
> + *
> + *	Byte 4
> + *	bit 7  Always 0
> + *	bit 6  B3
> + *	bit 5  B2
> + *	bit 4  B1
> + *	bit 3  B0
> + *	bit 2  P1 (optional)
> + *	bit 1  Y15
> + *	bit 0  Y14
> + *
> + *	Byte 5
> + *	bit 7  Always 0
> + *	bits 6-0 = Y13 - Y7
> + *
> + *	Byte 6
> + *	bit 7  Always 0
> + *	bits 6-0 = Y6 - Y0
> + *
> + *	Byte 7
> + *	bit 7 Always 0
> + *	bit 6  Sign of pressure data; or wheel-rel for cursor tool
> + *	bit 5  P7; or REL1 for cursor tool
> + *	bit 4  P6; or REL0 for cursor tool
> + *	bit 3  P5
> + *	bit 2  P4
> + *	bit 1  P3
> + *	bit 0  P2
> + *
> + *	byte 8 and 9 are optional and present only
> + *	in tilt mode.
> + *
> + *	Byte 8
> + *	bit 7 Always 0
> + *	bit 6 Sign of tilt X
> + *	bit 5  Xt6
> + *	bit 4  Xt5
> + *	bit 3  Xt4
> + *	bit 2  Xt3
> + *	bit 1  Xt2
> + *	bit 0  Xt1
> + *
> + *	Byte 9
> + *	bit 7 Always 0
> + *	bit 6 Sign of tilt Y
> + *	bit 5  Yt6
> + *	bit 4  Yt5
> + *	bit 3  Yt4
> + *	bit 2  Yt3
> + *	bit 1  Yt2
> + *	bit 0  Yt1
> + *
> + *	For more info see:
> + *	http://sourceforge.net/apps/mediawiki/linuxwacom/index.php?title=Serial_Protocol_IV

It looks this link is stale.

> + */
> +
> +#include <linux/completion.h>
> +#include <linux/init.h>
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/serio.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include "wacom_wac.h"
> +
> +MODULE_AUTHOR("Julian Squires <julian@cipht.net>, Hans de Goede <hdegoede@redhat.com>");
> +MODULE_DESCRIPTION("Wacom protocol 4 serial tablet driver");
> +MODULE_LICENSE("GPL");
> +
> +#define REQUEST_MODEL_AND_ROM_VERSION	"~#"
> +#define REQUEST_MAX_COORDINATES		"~C\r"
> +#define REQUEST_CONFIGURATION_STRING	"~R\r"
> +#define REQUEST_RESET_TO_PROTOCOL_IV	"\r#"
> +/* Note: sending "\r$\r" causes at least the Digitizer II to send
> + * packets in ASCII instead of binary.  "\r#" seems to undo that. */
> +
> +#define COMMAND_START_SENDING_PACKETS		"ST\r"
> +#define COMMAND_STOP_SENDING_PACKETS		"SP\r"
> +#define COMMAND_MULTI_MODE_INPUT		"MU1\r"
> +#define COMMAND_ORIGIN_IN_UPPER_LEFT		"OC1\r"
> +#define COMMAND_ENABLE_ALL_MACRO_BUTTONS	"~M0\r"
> +#define COMMAND_DISABLE_GROUP_1_MACRO_BUTTONS	"~M1\r"
> +#define COMMAND_TRANSMIT_AT_MAX_RATE		"IT0\r"
> +#define COMMAND_DISABLE_INCREMENTAL_MODE	"IN0\r"
> +#define COMMAND_ENABLE_CONTINUOUS_MODE		"SR\r"
> +#define COMMAND_ENABLE_PRESSURE_MODE		"PH1\r"
> +#define COMMAND_Z_FILTER			"ZF1\r"
> +
> +/* Note that this is a protocol 4 packet without tilt information. */
> +#define PACKET_LENGTH		7
> +#define DATA_SIZE		32
> +
> +/* flags */
> +#define F_COVERS_SCREEN		0x01
> +#define F_HAS_STYLUS2		0x02
> +#define F_HAS_SCROLLWHEEL	0x04
> +
> +enum { STYLUS = 1, ERASER, CURSOR };
> +struct { int device_id; int input_id; } tools[] = {
> +	{ 0, 0 },
> +	{ STYLUS_DEVICE_ID, BTN_TOOL_PEN },
> +	{ ERASER_DEVICE_ID, BTN_TOOL_RUBBER },
> +	{ CURSOR_DEVICE_ID, BTN_TOOL_MOUSE },
> +};
> +
> +struct wacom {
> +	struct input_dev *dev;
> +	struct completion cmd_done;
> +	int expect;
> +	int result;

I think these 2 should be u8.

> +	int extra_z_bits;
> +	int eraser_mask;
> +	int flags;
> +	int res_x, res_y;
> +	int max_x, max_y;
> +	int tool;
> +	int idx;

And these are unsigned ints.

> +	unsigned char data[DATA_SIZE];
> +	char phys[32];
> +};
> +
> +enum {
> +	MODEL_CINTIQ		= 0x504C, /* PL */
> +	MODEL_CINTIQ2		= 0x4454, /* DT */
> +	MODEL_DIGITIZER_II	= 0x5544, /* UD */
> +	MODEL_GRAPHIRE		= 0x4554, /* ET */
> +	MODEL_PENPARTNER	= 0x4354, /* CT */
> +};
> +
> +static void handle_model_response(struct wacom *wacom)
> +{
> +	int major_v, minor_v, r = 0;
> +	char *p;
> +
> +	p = strrchr(wacom->data, 'V');
> +	if (p)
> +		r = sscanf(p + 1, "%u.%u", &major_v, &minor_v);
> +	if (r != 2)
> +		major_v = minor_v = 0;
> +
> +	switch (wacom->data[2] << 8 | wacom->data[3]) {
> +	case MODEL_CINTIQ:	/* UNTESTED */
> +	case MODEL_CINTIQ2:
> +		if ((wacom->data[2] << 8 | wacom->data[3]) == MODEL_CINTIQ) {
> +			wacom->dev->name = "Wacom Cintiq";
> +			wacom->dev->id.version = MODEL_CINTIQ;
> +		} else {
> +			wacom->dev->name = "Wacom Cintiq II";
> +			wacom->dev->id.version = MODEL_CINTIQ2;
> +		}
> +		wacom->res_x = 508;
> +		wacom->res_y = 508;
> +		switch (wacom->data[5]<<8 | wacom->data[6]) {
> +		case 0x3731: /* PL-710 */
> +			wacom->res_x = 2540;
> +			wacom->res_y = 2540;
> +			/* fall through */
> +		case 0x3535: /* PL-550 */
> +		case 0x3830: /* PL-800 */
> +			wacom->extra_z_bits = 2;
> +		}
> +		wacom->flags = F_COVERS_SCREEN;
> +		break;
> +	case MODEL_PENPARTNER:
> +		wacom->dev->name = "Wacom Penpartner";
> +		wacom->dev->id.version = MODEL_PENPARTNER;
> +		wacom->res_x = 1000;
> +		wacom->res_y = 1000;
> +		break;
> +	case MODEL_GRAPHIRE:
> +		wacom->dev->name = "Wacom Graphire";
> +		wacom->dev->id.version = MODEL_GRAPHIRE;
> +		wacom->res_x = 1016;
> +		wacom->res_y = 1016;
> +		wacom->max_x = 5103;
> +		wacom->max_y = 3711;
> +		wacom->extra_z_bits = 2;
> +		wacom->eraser_mask = 0x08;
> +		wacom->flags = F_HAS_STYLUS2 | F_HAS_SCROLLWHEEL;
> +		break;
> +	case MODEL_DIGITIZER_II:
> +		wacom->dev->name = "Wacom Digitizer II";
> +		wacom->dev->id.version = MODEL_DIGITIZER_II;
> +		if (major_v == 1 && minor_v <= 2)
> +			wacom->extra_z_bits = 0; /* UNTESTED */
> +		break;
> +	default:
> +		dev_err(&wacom->dev->dev, "Unsupported Wacom model %s\n",
> +			wacom->data);
> +		wacom->result = -ENODEV;
> +		return;
> +	}
> +	dev_info(&wacom->dev->dev, "%s tablet, version %u.%u\n",
> +		 wacom->dev->name, major_v, minor_v);
> +}
> +
> +static void handle_configuration_response(struct wacom *wacom)
> +{
> +	int r, skip;
> +
> +	dev_dbg(&wacom->dev->dev, "Configuration string: %s\n", wacom->data);
> +	r = sscanf(wacom->data, "~R%x,%u,%u,%u,%u", &skip, &skip, &skip,
> +		   &wacom->res_x, &wacom->res_y);
> +	if (r != 5)
> +		dev_warn(&wacom->dev->dev, "could not get resolution\n");
> +}
> +
> +static void handle_coordinates_response(struct wacom *wacom)
> +{
> +	int r;
> +
> +	dev_dbg(&wacom->dev->dev, "Coordinates string: %s\n", wacom->data);
> +	r = sscanf(wacom->data, "~C%u,%u", &wacom->max_x, &wacom->max_y);
> +	if (r != 2)
> +		dev_warn(&wacom->dev->dev, "could not get max coordinates\n");
> +}
> +
> +static void handle_response(struct wacom *wacom)
> +{
> +	if (wacom->data[0] != '~' || wacom->data[1] != wacom->expect) {
> +		dev_err(&wacom->dev->dev,
> +			"Wacom got an unexpected response: %s\n", wacom->data);
> +		wacom->result = -EIO;
> +		complete(&wacom->cmd_done);
> +		return;
> +	}
> +
> +	wacom->result = 0;
> +
> +	switch (wacom->data[1]) {
> +	case '#':
> +		handle_model_response(wacom);
> +		break;
> +	case 'R':
> +		handle_configuration_response(wacom);
> +		break;
> +	case 'C':
> +		handle_coordinates_response(wacom);
> +		break;
> +	}
> +
> +	complete(&wacom->cmd_done);
> +}
> +
> +static void handle_packet(struct wacom *wacom)
> +{
> +	int in_proximity_p, stylus_p, button, x, y, z;
> +	int tool;
> +
> +	in_proximity_p = wacom->data[0] & 0x40;
> +	stylus_p = wacom->data[0] & 0x20;
> +	button = (wacom->data[3] & 0x78) >> 3;
> +	x = (wacom->data[0] & 3) << 14 | wacom->data[1]<<7 | wacom->data[2];
> +	y = (wacom->data[3] & 3) << 14 | wacom->data[4]<<7 | wacom->data[5];
> +
> +	if (in_proximity_p && stylus_p) {
> +		z = wacom->data[6] & 0x7f;
> +		if (wacom->extra_z_bits >= 1)
> +			z = z << 1 | (wacom->data[3] & 0x4) >> 2;
> +		if (wacom->extra_z_bits > 1)
> +			z = z << 1 | (wacom->data[0] & 0x4) >> 2;
> +		z = z ^ (0x40 << wacom->extra_z_bits);
> +	} else {
> +		z = -1;

I do not believe it is nice to send -1 as pressure. What does it even
mean to userspace? Does wacom_usb do this as well?

> +	}
> +
> +	if (stylus_p)
> +		tool = (button & wacom->eraser_mask) ? ERASER : STYLUS;
> +	else
> +		tool = CURSOR;
> +
> +	if (tool != wacom->tool && wacom->tool != 0) {
> +		input_report_key(wacom->dev, tools[wacom->tool].input_id, 0);
> +		input_sync(wacom->dev);
> +	}
> +	wacom->tool = tool;
> +
> +	input_report_key(wacom->dev, tools[tool].input_id, in_proximity_p);
> +	input_report_abs(wacom->dev, ABS_MISC,
> +			 in_proximity_p ? tools[tool].device_id : 0);
> +	input_report_abs(wacom->dev, ABS_X, x);
> +	input_report_abs(wacom->dev, ABS_Y, y);
> +	input_report_abs(wacom->dev, ABS_PRESSURE, z);
> +	if (stylus_p) {
> +		input_report_key(wacom->dev, BTN_TOUCH, button & 1);
> +		input_report_key(wacom->dev, BTN_STYLUS, button & 2);
> +		input_report_key(wacom->dev, BTN_STYLUS2, button & 4);
> +	} else {
> +		input_report_key(wacom->dev, BTN_LEFT, button & 1);
> +		input_report_key(wacom->dev, BTN_RIGHT, button & 2);
> +		input_report_key(wacom->dev, BTN_MIDDLE, button & 4);
> +		/* handle relative wheel for non-stylus device */
> +		z = (wacom->data[6] & 0x30) >> 4;
> +		if (wacom->data[6] & 0x40)
> +			z = -z;
> +		input_report_rel(wacom->dev, REL_WHEEL, z);
> +	}
> +	input_sync(wacom->dev);
> +}
> +
> +static void wacom_clear_data_buf(struct wacom *wacom)
> +{
> +	memset(wacom->data, 0, DATA_SIZE);
> +	wacom->idx = 0;
> +}
> +
> +static irqreturn_t wacom_interrupt(struct serio *serio, unsigned char data,
> +				   unsigned int flags)
> +{
> +	struct wacom *wacom = serio_get_drvdata(serio);
> +
> +	if (data & 0x80)
> +		wacom->idx = 0;
> +
> +	/*
> +	 * We're either expecting a carriage return-terminated ASCII
> +	 * response string, or a seven-byte packet with the MSB set on
> +	 * the first byte.
> +	 *
> +	 * Note however that some tablets (the PenPartner, for
> +	 * example) don't send a carriage return at the end of a
> +	 * command.  We handle these by waiting for timeout.
> +	 */
> +	if (data == '\r' && !(wacom->data[0] & 0x80)) {
> +		handle_response(wacom);
> +		wacom_clear_data_buf(wacom);
> +		return IRQ_HANDLED;
> +	}
> +
> +	/* Leave place for 0 termination */
> +	if (wacom->idx > (DATA_SIZE - 2)) {
> +		dev_dbg(&wacom->dev->dev,
> +			"throwing away %d bytes of garbage\n", wacom->idx);
> +		wacom_clear_data_buf(wacom);
> +	}
> +	wacom->data[wacom->idx++] = data;
> +
> +	if (wacom->idx == PACKET_LENGTH && (wacom->data[0] & 0x80)) {
> +		handle_packet(wacom);
> +		wacom_clear_data_buf(wacom);
> +	}
> +	return IRQ_HANDLED;
> +}
> +
> +static void wacom_disconnect(struct serio *serio)
> +{
> +	struct wacom *wacom = serio_get_drvdata(serio);
> +
> +	serio_close(serio);
> +	serio_set_drvdata(serio, NULL);
> +	input_unregister_device(wacom->dev);
> +	kfree(wacom);
> +}
> +
> +static int wacom_send(struct serio *serio, const char *command)
> +{
> +	int err = 0;
> +
> +	for (; !err && *command; command++)
> +		err = serio_write(serio, *command);
> +
> +	return err;
> +}
> +
> +static int send_setup_string(struct wacom *wacom, struct serio *serio)
> +{
> +	const char *s;
> +
> +	switch (wacom->dev->id.version) {
> +	case MODEL_CINTIQ:	/* UNTESTED */
> +		s = COMMAND_ORIGIN_IN_UPPER_LEFT
> +			COMMAND_TRANSMIT_AT_MAX_RATE
> +			COMMAND_ENABLE_CONTINUOUS_MODE
> +			COMMAND_START_SENDING_PACKETS;
> +		break;
> +	case MODEL_PENPARTNER:
> +		s = COMMAND_ENABLE_PRESSURE_MODE
> +			COMMAND_START_SENDING_PACKETS;
> +		break;
> +	default:
> +		s = COMMAND_MULTI_MODE_INPUT
> +			COMMAND_ORIGIN_IN_UPPER_LEFT
> +			COMMAND_ENABLE_ALL_MACRO_BUTTONS
> +			COMMAND_DISABLE_GROUP_1_MACRO_BUTTONS
> +			COMMAND_TRANSMIT_AT_MAX_RATE
> +			COMMAND_DISABLE_INCREMENTAL_MODE
> +			COMMAND_ENABLE_CONTINUOUS_MODE
> +			COMMAND_Z_FILTER
> +			COMMAND_START_SENDING_PACKETS;
> +		break;
> +	}
> +	return wacom_send(serio, s);
> +}
> +
> +static int wacom_send_and_wait(struct wacom *wacom, struct serio *serio,
> +	const char *cmd, const char *desc)
> +{
> +	int err;
> +	unsigned long u;
> +
> +	wacom->expect = cmd[1];
> +	init_completion(&wacom->cmd_done);
> +	err = wacom_send(serio, cmd);
> +	if (err)
> +		return err;
> +	u = wait_for_completion_timeout(&wacom->cmd_done, HZ);
> +	if (u == 0) {
> +		/* Timeout, process what we've received. */
> +		handle_response(wacom);
> +	}
> +	wacom->expect = 0;
> +	return wacom->result;
> +}
> +
> +static int wacom_setup(struct wacom *wacom, struct serio *serio)
> +{
> +	int err;
> +
> +	/* Note that setting the link speed is the job of inputattach.
> +	 * We assume that reset negotiation has already happened,
> +	 * here. */
> +	err = wacom_send_and_wait(wacom, serio, REQUEST_MODEL_AND_ROM_VERSION,
> +				  "model and version");
> +	if (err)
> +		return err;
> +
> +	if (!(wacom->res_x && wacom->res_y)) {
> +		err = wacom_send_and_wait(wacom, serio,
> +					  REQUEST_CONFIGURATION_STRING,
> +					  "configuration string");
> +		if (err)
> +			return err;
> +	}
> +
> +	if (!(wacom->max_x && wacom->max_y)) {
> +		err = wacom_send_and_wait(wacom, serio,
> +					  REQUEST_MAX_COORDINATES,
> +					  "coordinates string");
> +		if (err)
> +			return err;
> +	}
> +
> +	return send_setup_string(wacom, serio);
> +}
> +
> +static int wacom_connect(struct serio *serio, struct serio_driver *drv)
> +{
> +	struct wacom *wacom;
> +	struct input_dev *input_dev;
> +	int err = -ENOMEM;
> +
> +	wacom = kzalloc(sizeof(struct wacom), GFP_KERNEL);
> +	input_dev = input_allocate_device();
> +	if (!wacom || !input_dev)
> +		goto free_device;
> +
> +	wacom->dev = input_dev;
> +	wacom->extra_z_bits = 1;
> +	wacom->eraser_mask = 0x04;
> +	wacom->tool = wacom->idx = 0;
> +	snprintf(wacom->phys, sizeof(wacom->phys), "%s/input0", serio->phys);
> +	input_dev->phys = wacom->phys;
> +	input_dev->id.bustype = BUS_RS232;
> +	input_dev->id.vendor  = SERIO_WACOM_IV;
> +	input_dev->id.product = serio->id.extra;
> +	input_dev->dev.parent = &serio->dev;
> +
> +	input_dev->evbit[0] =
> +		BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) | BIT_MASK(EV_REL);
> +	set_bit(ABS_MISC, input_dev->absbit);
> +	set_bit(BTN_TOOL_PEN, input_dev->keybit);
> +	set_bit(BTN_TOOL_RUBBER, input_dev->keybit);
> +	set_bit(BTN_TOOL_MOUSE, input_dev->keybit);
> +	set_bit(BTN_TOUCH, input_dev->keybit);
> +	set_bit(BTN_STYLUS, input_dev->keybit);
> +	set_bit(BTN_LEFT, input_dev->keybit);
> +	set_bit(BTN_RIGHT, input_dev->keybit);
> +	set_bit(BTN_MIDDLE, input_dev->keybit);
> +
> +	serio_set_drvdata(serio, wacom);
> +
> +	err = serio_open(serio, drv);
> +	if (err)
> +		goto free_device;
> +
> +	err = wacom_setup(wacom, serio);
> +	if (err)
> +		goto close_serio;
> +
> +	set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
> +	if (!(wacom->flags & F_COVERS_SCREEN))
> +		set_bit(INPUT_PROP_POINTER, input_dev->propbit);
> +
> +	if (wacom->flags & F_HAS_STYLUS2)
> +		set_bit(BTN_STYLUS2, input_dev->keybit);
> +
> +	if (wacom->flags & F_HAS_SCROLLWHEEL)
> +		set_bit(REL_WHEEL, input_dev->relbit);
> +
> +	input_abs_set_res(wacom->dev, ABS_X, wacom->res_x);
> +	input_abs_set_res(wacom->dev, ABS_Y, wacom->res_y);
> +	input_set_abs_params(wacom->dev, ABS_X, 0, wacom->max_x, 0, 0);
> +	input_set_abs_params(wacom->dev, ABS_Y, 0, wacom->max_y, 0, 0);
> +	input_set_abs_params(wacom->dev, ABS_PRESSURE, -1,
> +			     (1 << (7 + wacom->extra_z_bits)) - 1, 0, 0);
> +
> +	err = input_register_device(wacom->dev);
> +	if (err)
> +		goto close_serio;
> +
> +	return 0;
> +
> +close_serio:
> +	serio_close(serio);
> +free_device:
> +	serio_set_drvdata(serio, NULL);
> +	input_free_device(input_dev);
> +	kfree(wacom);
> +	return err;
> +}
> +
> +static struct serio_device_id wacom_serio_ids[] = {
> +	{
> +		.type	= SERIO_RS232,
> +		.proto	= SERIO_WACOM_IV,
> +		.id	= SERIO_ANY,
> +		.extra	= SERIO_ANY,
> +	},
> +	{ 0 }
> +};
> +
> +MODULE_DEVICE_TABLE(serio, wacom_serio_ids);
> +
> +static struct serio_driver wacom_drv = {
> +	.driver		= {
> +		.name	= "wacom_serial4",
> +	},
> +	.description	= "Wacom protocol 4 serial tablet driver",
> +	.id_table	= wacom_serio_ids,
> +	.interrupt	= wacom_interrupt,
> +	.connect	= wacom_connect,
> +	.disconnect	= wacom_disconnect,
> +};
> +
> +module_serio_driver(wacom_drv);
> diff --git a/include/uapi/linux/serio.h b/include/uapi/linux/serio.h
> index 9f53fa7..becdd78 100644
> --- a/include/uapi/linux/serio.h
> +++ b/include/uapi/linux/serio.h
> @@ -76,5 +76,6 @@
>  #define SERIO_HAMPSHIRE	0x3b
>  #define SERIO_PS2MULT	0x3c
>  #define SERIO_TSC40	0x3d
> +#define SERIO_WACOM_IV	0x3e
>  
>  #endif /* _UAPI_SERIO_H */
> -- 
> 2.0.1
> 

Thanks.

-- 
Dmitry