// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Wacom protocol 4 serial tablet driver
 *
 * Copyright 2014      Hans de Goede <hdegoede@redhat.com>
 * Copyright 2011-2012 Julian Squires <julian@cipht.net>
 *
 * 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>

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

/* device IDs */
#define STYLUS_DEVICE_ID        0x02
#define CURSOR_DEVICE_ID        0x06
#define ERASER_DEVICE_ID        0x0A

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 */
        MODEL_ARTPAD_II         = 0x4B54, /* KT */
};

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;
                        fallthrough;
                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_ARTPAD_II:
        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_obj(*wacom);
        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 const 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);