// SPDX-License-Identifier: GPL-2.0-only
/*
 * Elo serial touchscreen driver
 *
 * Copyright (c) 2004 Vojtech Pavlik
 */


/*
 * This driver can handle serial Elo touchscreens using either the Elo standard
 * 'E271-2210' 10-byte protocol, Elo legacy 'E281A-4002' 6-byte protocol, Elo
 * legacy 'E271-140' 4-byte protocol and Elo legacy 'E261-280' 3-byte protocol.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/ctype.h>

#define DRIVER_DESC     "Elo serial touchscreen driver"

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define ELO_MAX_LENGTH          10

#define ELO10_PACKET_LEN        8
#define ELO10_TOUCH             0x03
#define ELO10_PRESSURE          0x80

#define ELO10_LEAD_BYTE         'U'

#define ELO10_ID_CMD            'i'

#define ELO10_TOUCH_PACKET      'T'
#define ELO10_ACK_PACKET        'A'
#define ELI10_ID_PACKET         'I'

/*
 * Per-touchscreen data.
 */

struct elo {
        struct input_dev *dev;
        struct serio *serio;
        struct mutex cmd_mutex;
        struct completion cmd_done;
        int id;
        int idx;
        unsigned char expected_packet;
        unsigned char csum;
        unsigned char data[ELO_MAX_LENGTH];
        unsigned char response[ELO10_PACKET_LEN];
        char phys[32];
};

static void elo_process_data_10(struct elo *elo, unsigned char data)
{
        struct input_dev *dev = elo->dev;

        elo->data[elo->idx] = data;

        switch (elo->idx++) {
        case 0:
                elo->csum = 0xaa;
                if (data != ELO10_LEAD_BYTE) {
                        dev_dbg(&elo->serio->dev,
                                "unsynchronized data: 0x%02x\n", data);
                        elo->idx = 0;
                }
                break;

        case 9:
                elo->idx = 0;
                if (data != elo->csum) {
                        dev_dbg(&elo->serio->dev,
                                "bad checksum: 0x%02x, expected 0x%02x\n",
                                 data, elo->csum);
                        break;
                }
                if (elo->data[1] != elo->expected_packet) {
                        if (elo->data[1] != ELO10_TOUCH_PACKET)
                                dev_dbg(&elo->serio->dev,
                                        "unexpected packet: 0x%02x\n",
                                         elo->data[1]);
                        break;
                }
                if (likely(elo->data[1] == ELO10_TOUCH_PACKET)) {
                        input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
                        input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
                        if (elo->data[2] & ELO10_PRESSURE)
                                input_report_abs(dev, ABS_PRESSURE,
                                                (elo->data[8] << 8) | elo->data[7]);
                        input_report_key(dev, BTN_TOUCH, elo->data[2] & ELO10_TOUCH);
                        input_sync(dev);
                } else if (elo->data[1] == ELO10_ACK_PACKET) {
                        if (elo->data[2] == '0')
                                elo->expected_packet = ELO10_TOUCH_PACKET;
                        complete(&elo->cmd_done);
                } else {
                        memcpy(elo->response, &elo->data[1], ELO10_PACKET_LEN);
                        elo->expected_packet = ELO10_ACK_PACKET;
                }
                break;
        }
        elo->csum += data;
}

static void elo_process_data_6(struct elo *elo, unsigned char data)
{
        struct input_dev *dev = elo->dev;

        elo->data[elo->idx] = data;

        switch (elo->idx++) {

        case 0:
                if ((data & 0xc0) != 0xc0)
                        elo->idx = 0;
                break;

        case 1:
                if ((data & 0xc0) != 0x80)
                        elo->idx = 0;
                break;

        case 2:
                if ((data & 0xc0) != 0x40)
                        elo->idx = 0;
                break;

        case 3:
                if (data & 0xc0) {
                        elo->idx = 0;
                        break;
                }

                input_report_abs(dev, ABS_X, ((elo->data[0] & 0x3f) << 6) | (elo->data[1] & 0x3f));
                input_report_abs(dev, ABS_Y, ((elo->data[2] & 0x3f) << 6) | (elo->data[3] & 0x3f));

                if (elo->id == 2) {
                        input_report_key(dev, BTN_TOUCH, 1);
                        input_sync(dev);
                        elo->idx = 0;
                }

                break;

        case 4:
                if (data) {
                        input_sync(dev);
                        elo->idx = 0;
                }
                break;

        case 5:
                if ((data & 0xf0) == 0) {
                        input_report_abs(dev, ABS_PRESSURE, elo->data[5]);
                        input_report_key(dev, BTN_TOUCH, !!elo->data[5]);
                }
                input_sync(dev);
                elo->idx = 0;
                break;
        }
}

static void elo_process_data_3(struct elo *elo, unsigned char data)
{
        struct input_dev *dev = elo->dev;

        elo->data[elo->idx] = data;

        switch (elo->idx++) {

        case 0:
                if ((data & 0x7f) != 0x01)
                        elo->idx = 0;
                break;
        case 2:
                input_report_key(dev, BTN_TOUCH, !(elo->data[1] & 0x80));
                input_report_abs(dev, ABS_X, elo->data[1]);
                input_report_abs(dev, ABS_Y, elo->data[2]);
                input_sync(dev);
                elo->idx = 0;
                break;
        }
}

static irqreturn_t elo_interrupt(struct serio *serio,
                unsigned char data, unsigned int flags)
{
        struct elo *elo = serio_get_drvdata(serio);

        switch (elo->id) {
        case 0:
                elo_process_data_10(elo, data);
                break;

        case 1:
        case 2:
                elo_process_data_6(elo, data);
                break;

        case 3:
                elo_process_data_3(elo, data);
                break;
        }

        return IRQ_HANDLED;
}

static int elo_command_10(struct elo *elo, unsigned char *packet)
{
        int rc = -1;
        int i;
        unsigned char csum = 0xaa + ELO10_LEAD_BYTE;

        mutex_lock(&elo->cmd_mutex);

        scoped_guard(serio_pause_rx, elo->serio) {
                elo->expected_packet = toupper(packet[0]);
                init_completion(&elo->cmd_done);
        }

        if (serio_write(elo->serio, ELO10_LEAD_BYTE))
                goto out;

        for (i = 0; i < ELO10_PACKET_LEN; i++) {
                csum += packet[i];
                if (serio_write(elo->serio, packet[i]))
                        goto out;
        }

        if (serio_write(elo->serio, csum))
                goto out;

        wait_for_completion_timeout(&elo->cmd_done, HZ);

        if (elo->expected_packet == ELO10_TOUCH_PACKET) {
                /* We are back in reporting mode, the command was ACKed */
                memcpy(packet, elo->response, ELO10_PACKET_LEN);
                rc = 0;
        }

 out:
        mutex_unlock(&elo->cmd_mutex);
        return rc;
}

static int elo_setup_10(struct elo *elo)
{
        static const char *elo_types[] = { "Accu", "Dura", "Intelli", "Carroll" };
        struct input_dev *dev = elo->dev;
        unsigned char packet[ELO10_PACKET_LEN] = { ELO10_ID_CMD };

        if (elo_command_10(elo, packet))
                return -1;

        dev->id.version = (packet[5] << 8) | packet[4];

        input_set_abs_params(dev, ABS_X, 96, 4000, 0, 0);
        input_set_abs_params(dev, ABS_Y, 96, 4000, 0, 0);
        if (packet[3] & ELO10_PRESSURE)
                input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);

        dev_info(&elo->serio->dev,
                 "%sTouch touchscreen, fw: %02x.%02x, features: 0x%02x, controller: 0x%02x\n",
                 elo_types[(packet[1] -'0') & 0x03],
                 packet[5], packet[4], packet[3], packet[7]);

        return 0;
}

/*
 * elo_disconnect() is the opposite of elo_connect()
 */

static void elo_disconnect(struct serio *serio)
{
        struct elo *elo = serio_get_drvdata(serio);

        input_get_device(elo->dev);
        input_unregister_device(elo->dev);
        serio_close(serio);
        serio_set_drvdata(serio, NULL);
        input_put_device(elo->dev);
        kfree(elo);
}

/*
 * elo_connect() is the routine that is called when someone adds a
 * new serio device that supports Gunze protocol and registers it as
 * an input device.
 */

static int elo_connect(struct serio *serio, struct serio_driver *drv)
{
        struct elo *elo;
        struct input_dev *input_dev;
        int err;

        elo = kzalloc_obj(*elo);
        input_dev = input_allocate_device();
        if (!elo || !input_dev) {
                err = -ENOMEM;
                goto fail1;
        }

        elo->serio = serio;
        elo->id = serio->id.id;
        elo->dev = input_dev;
        elo->expected_packet = ELO10_TOUCH_PACKET;
        mutex_init(&elo->cmd_mutex);
        init_completion(&elo->cmd_done);
        scnprintf(elo->phys, sizeof(elo->phys), "%s/input0", serio->phys);

        input_dev->name = "Elo Serial TouchScreen";
        input_dev->phys = elo->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_ELO;
        input_dev->id.product = elo->id;
        input_dev->id.version = 0x0100;
        input_dev->dev.parent = &serio->dev;

        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
        input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

        serio_set_drvdata(serio, elo);
        err = serio_open(serio, drv);
        if (err)
                goto fail2;

        switch (elo->id) {

        case 0: /* 10-byte protocol */
                if (elo_setup_10(elo)) {
                        err = -EIO;
                        goto fail3;
                }

                break;

        case 1: /* 6-byte protocol */
                input_set_abs_params(input_dev, ABS_PRESSURE, 0, 15, 0, 0);
                fallthrough;

        case 2: /* 4-byte protocol */
                input_set_abs_params(input_dev, ABS_X, 96, 4000, 0, 0);
                input_set_abs_params(input_dev, ABS_Y, 96, 4000, 0, 0);
                break;

        case 3: /* 3-byte protocol */
                input_set_abs_params(input_dev, ABS_X, 0, 255, 0, 0);
                input_set_abs_params(input_dev, ABS_Y, 0, 255, 0, 0);
                break;
        }

        err = input_register_device(elo->dev);
        if (err)
                goto fail3;

        return 0;

 fail3: serio_close(serio);
 fail2: serio_set_drvdata(serio, NULL);
 fail1: input_free_device(input_dev);
        kfree(elo);
        return err;
}

/*
 * The serio driver structure.
 */

static const struct serio_device_id elo_serio_ids[] = {
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_ELO,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        { 0 }
};

MODULE_DEVICE_TABLE(serio, elo_serio_ids);

static struct serio_driver elo_drv = {
        .driver         = {
                .name   = "elo",
        },
        .description    = DRIVER_DESC,
        .id_table       = elo_serio_ids,
        .interrupt      = elo_interrupt,
        .connect        = elo_connect,
        .disconnect     = elo_disconnect,
};

module_serio_driver(elo_drv);