5 files changed, 635 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 51ebb779c5f3..c68bd8b6f8e9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9708,6 +9708,13 @@ 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 bed7cbf84cfd..a5121b09c63f 100644
--- a/drivers/input/tablet/Kconfig
+++ b/drivers/input/tablet/Kconfig
@@ -89,4 +89,14 @@ 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.
+
+          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 3f6c25220638..4d9339fb3b63 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 000000000000..d3d251e27307
--- /dev/null
+++ b/drivers/input/tablet/wacom_serial4.c
@@ -0,0 +1,616 @@
+/*
+ * 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
+ */
+
+#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 };
+
+static const 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 result;
+        u8 expect;
+        u8 eraser_mask;
+        unsigned int extra_z_bits;
+        unsigned int flags;
+        unsigned int res_x, res_y;
+        unsigned int max_x, max_y;
+        unsigned int tool;
+        unsigned int idx;
+        u8 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 wacom_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 wacom_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 wacom_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 wacom_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;
+        } else {
+                wacom->result = 0;
+
+                switch (wacom->data[1]) {
+                case '#':
+                        wacom_handle_model_response(wacom);
+                        break;
+                case 'R':
+                        wacom_handle_configuration_response(wacom);
+                        break;
+                case 'C':
+                        wacom_handle_coordinates_response(wacom);
+                        break;
+                }
+        }
+
+        complete(&wacom->cmd_done);
+}
+
+static void wacom_handle_packet(struct wacom *wacom)
+{
+        u8 in_proximity_p, stylus_p, button;
+        unsigned int tool;
+        int x, y, z;
+
+        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;
+        }
+
+        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)) {
+                wacom_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)) {
+                wacom_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 u8 *command)
+{
+        int err = 0;
+
+        for (; !err && *command; command++)
+                err = serio_write(serio, *command);
+
+        return err;
+}
+
+static int wacom_send_setup_string(struct wacom *wacom, struct serio *serio)
+{
+        const u8 *cmd;
+
+        switch (wacom->dev->id.version) {
+        case MODEL_CINTIQ:      /* UNTESTED */
+                cmd = COMMAND_ORIGIN_IN_UPPER_LEFT
+                        COMMAND_TRANSMIT_AT_MAX_RATE
+                        COMMAND_ENABLE_CONTINUOUS_MODE
+                        COMMAND_START_SENDING_PACKETS;
+                break;
+
+        case MODEL_PENPARTNER:
+                cmd = COMMAND_ENABLE_PRESSURE_MODE
+                        COMMAND_START_SENDING_PACKETS;
+                break;
+
+        default:
+                cmd = 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, cmd);
+}
+
+static int wacom_send_and_wait(struct wacom *wacom, struct serio *serio,
+                               const u8 *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. */
+                wacom_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 wacom_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 9f53fa7fc132..becdd78295cc 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 */