// SPDX-License-Identifier: GPL-2.0-only
/*
 * Penmount serial touchscreen driver
 *
 * Copyright (c) 2006 Rick Koch <n1gp@hotmail.com>
 * Copyright (c) 2011 John Sung <penmount.touch@gmail.com>
 *
 * Based on ELO driver (drivers/input/touchscreen/elo.c)
 * Copyright (c) 2004 Vojtech Pavlik
 */


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

#define DRIVER_DESC     "PenMount serial touchscreen driver"

MODULE_AUTHOR("Rick Koch <n1gp@hotmail.com>");
MODULE_AUTHOR("John Sung <penmount.touch@gmail.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define PM_MAX_LENGTH   6
#define PM_MAX_MTSLOT   16
#define PM_3000_MTSLOT  2
#define PM_6250_MTSLOT  12

/*
 * Multi-touch slot
 */

struct mt_slot {
        unsigned short x, y;
        bool active; /* is the touch valid? */
};

/*
 * Per-touchscreen data.
 */

struct pm {
        struct input_dev *dev;
        struct serio *serio;
        int idx;
        unsigned char data[PM_MAX_LENGTH];
        char phys[32];
        unsigned char packetsize;
        unsigned char maxcontacts;
        struct mt_slot slots[PM_MAX_MTSLOT];
        void (*parse_packet)(struct pm *);
};

/*
 * pm_mtevent() sends mt events and also emulates pointer movement
 */

static void pm_mtevent(struct pm *pm, struct input_dev *input)
{
        int i;

        for (i = 0; i < pm->maxcontacts; ++i) {
                input_mt_slot(input, i);
                input_mt_report_slot_state(input, MT_TOOL_FINGER,
                                pm->slots[i].active);
                if (pm->slots[i].active) {
                        input_event(input, EV_ABS, ABS_MT_POSITION_X, pm->slots[i].x);
                        input_event(input, EV_ABS, ABS_MT_POSITION_Y, pm->slots[i].y);
                }
        }

        input_mt_report_pointer_emulation(input, true);
        input_sync(input);
}

/*
 * pm_checkpacket() checks if data packet is valid
 */

static bool pm_checkpacket(unsigned char *packet)
{
        int total = 0;
        int i;

        for (i = 0; i < 5; i++)
                total += packet[i];

        return packet[5] == (unsigned char)~(total & 0xff);
}

static void pm_parse_9000(struct pm *pm)
{
        struct input_dev *dev = pm->dev;

        if ((pm->data[0] & 0x80) && pm->packetsize == ++pm->idx) {
                input_report_abs(dev, ABS_X, pm->data[1] * 128 + pm->data[2]);
                input_report_abs(dev, ABS_Y, pm->data[3] * 128 + pm->data[4]);
                input_report_key(dev, BTN_TOUCH, !!(pm->data[0] & 0x40));
                input_sync(dev);
                pm->idx = 0;
        }
}

static void pm_parse_6000(struct pm *pm)
{
        struct input_dev *dev = pm->dev;

        if ((pm->data[0] & 0xbf) == 0x30 && pm->packetsize == ++pm->idx) {
                if (pm_checkpacket(pm->data)) {
                        input_report_abs(dev, ABS_X,
                                        pm->data[2] * 256 + pm->data[1]);
                        input_report_abs(dev, ABS_Y,
                                        pm->data[4] * 256 + pm->data[3]);
                        input_report_key(dev, BTN_TOUCH, pm->data[0] & 0x40);
                        input_sync(dev);
                }
                pm->idx = 0;
        }
}

static void pm_parse_3000(struct pm *pm)
{
        struct input_dev *dev = pm->dev;

        if ((pm->data[0] & 0xce) == 0x40 && pm->packetsize == ++pm->idx) {
                if (pm_checkpacket(pm->data)) {
                        int slotnum = pm->data[0] & 0x0f;
                        pm->slots[slotnum].active = pm->data[0] & 0x30;
                        pm->slots[slotnum].x = pm->data[2] * 256 + pm->data[1];
                        pm->slots[slotnum].y = pm->data[4] * 256 + pm->data[3];
                        pm_mtevent(pm, dev);
                }
                pm->idx = 0;
        }
}

static void pm_parse_6250(struct pm *pm)
{
        struct input_dev *dev = pm->dev;

        if ((pm->data[0] & 0xb0) == 0x30 && pm->packetsize == ++pm->idx) {
                if (pm_checkpacket(pm->data)) {
                        int slotnum = pm->data[0] & 0x0f;
                        pm->slots[slotnum].active = pm->data[0] & 0x40;
                        pm->slots[slotnum].x = pm->data[2] * 256 + pm->data[1];
                        pm->slots[slotnum].y = pm->data[4] * 256 + pm->data[3];
                        pm_mtevent(pm, dev);
                }
                pm->idx = 0;
        }
}

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

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

        pm->parse_packet(pm);

        return IRQ_HANDLED;
}

/*
 * pm_disconnect() is the opposite of pm_connect()
 */

static void pm_disconnect(struct serio *serio)
{
        struct pm *pm = serio_get_drvdata(serio);

        serio_close(serio);

        input_unregister_device(pm->dev);
        kfree(pm);

        serio_set_drvdata(serio, NULL);
}

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

static int pm_connect(struct serio *serio, struct serio_driver *drv)
{
        struct pm *pm;
        struct input_dev *input_dev;
        int max_x, max_y;
        int err;

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

        pm->serio = serio;
        pm->dev = input_dev;
        scnprintf(pm->phys, sizeof(pm->phys), "%s/input0", serio->phys);
        pm->maxcontacts = 1;

        input_dev->name = "PenMount Serial TouchScreen";
        input_dev->phys = pm->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_PENMOUNT;
        input_dev->id.product = 0;
        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);

        switch (serio->id.id) {
        default:
        case 0:
                pm->packetsize = 5;
                pm->parse_packet = pm_parse_9000;
                input_dev->id.product = 0x9000;
                max_x = max_y = 0x3ff;
                break;

        case 1:
                pm->packetsize = 6;
                pm->parse_packet = pm_parse_6000;
                input_dev->id.product = 0x6000;
                max_x = max_y = 0x3ff;
                break;

        case 2:
                pm->packetsize = 6;
                pm->parse_packet = pm_parse_3000;
                input_dev->id.product = 0x3000;
                max_x = max_y = 0x7ff;
                pm->maxcontacts = PM_3000_MTSLOT;
                break;

        case 3:
                pm->packetsize = 6;
                pm->parse_packet = pm_parse_6250;
                input_dev->id.product = 0x6250;
                max_x = max_y = 0x3ff;
                pm->maxcontacts = PM_6250_MTSLOT;
                break;
        }

        input_set_abs_params(pm->dev, ABS_X, 0, max_x, 0, 0);
        input_set_abs_params(pm->dev, ABS_Y, 0, max_y, 0, 0);

        if (pm->maxcontacts > 1) {
                input_mt_init_slots(pm->dev, pm->maxcontacts, 0);
                input_set_abs_params(pm->dev,
                                     ABS_MT_POSITION_X, 0, max_x, 0, 0);
                input_set_abs_params(pm->dev,
                                     ABS_MT_POSITION_Y, 0, max_y, 0, 0);
        }

        serio_set_drvdata(serio, pm);

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

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

        return 0;

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

/*
 * The serio driver structure.
 */

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

MODULE_DEVICE_TABLE(serio, pm_serio_ids);

static struct serio_driver pm_drv = {
        .driver         = {
                .name   = "serio-penmount",
        },
        .description    = DRIVER_DESC,
        .id_table       = pm_serio_ids,
        .interrupt      = pm_interrupt,
        .connect        = pm_connect,
        .disconnect     = pm_disconnect,
};

module_serio_driver(pm_drv);