// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (c) 1999-2001 Vojtech Pavlik
 */

/*
 *  Serial mouse driver for Linux
 */

#include <linux/delay.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/serio.h>

#define DRIVER_DESC     "Serial mouse driver"

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

static const char *sermouse_protocols[] = { "None", "Mouse Systems Mouse", "Sun Mouse", "Microsoft Mouse",
                                        "Logitech M+ Mouse", "Microsoft MZ Mouse", "Logitech MZ+ Mouse",
                                        "Logitech MZ++ Mouse"};

struct sermouse {
        struct input_dev *dev;
        signed char buf[8];
        unsigned char count;
        unsigned char type;
        unsigned long last;
        char phys[32];
};

/*
 * sermouse_process_msc() analyzes the incoming MSC/Sun bytestream and
 * applies some prediction to the data, resulting in 96 updates per
 * second, which is as good as a PS/2 or USB mouse.
 */

static void sermouse_process_msc(struct sermouse *sermouse, signed char data)
{
        struct input_dev *dev = sermouse->dev;
        signed char *buf = sermouse->buf;

        switch (sermouse->count) {

                case 0:
                        if ((data & 0xf8) != 0x80)
                                return;
                        input_report_key(dev, BTN_LEFT,   !(data & 4));
                        input_report_key(dev, BTN_RIGHT,  !(data & 1));
                        input_report_key(dev, BTN_MIDDLE, !(data & 2));
                        break;

                case 1:
                case 3:
                        input_report_rel(dev, REL_X, data / 2);
                        input_report_rel(dev, REL_Y, -buf[1]);
                        buf[0] = data - data / 2;
                        break;

                case 2:
                case 4:
                        input_report_rel(dev, REL_X, buf[0]);
                        input_report_rel(dev, REL_Y, buf[1] - data);
                        buf[1] = data / 2;
                        break;
        }

        input_sync(dev);

        if (++sermouse->count == 5)
                sermouse->count = 0;
}

/*
 * sermouse_process_ms() anlyzes the incoming MS(Z/+/++) bytestream and
 * generates events. With prediction it gets 80 updates/sec, assuming
 * standard 3-byte packets and 1200 bps.
 */

static void sermouse_process_ms(struct sermouse *sermouse, signed char data)
{
        struct input_dev *dev = sermouse->dev;
        signed char *buf = sermouse->buf;

        if (data & 0x40)
                sermouse->count = 0;
        else if (sermouse->count == 0)
                return;

        switch (sermouse->count) {

                case 0:
                        buf[1] = data;
                        input_report_key(dev, BTN_LEFT,   (data >> 5) & 1);
                        input_report_key(dev, BTN_RIGHT,  (data >> 4) & 1);
                        break;

                case 1:
                        buf[2] = data;
                        data = (signed char) (((buf[1] << 6) & 0xc0) | (data & 0x3f));
                        input_report_rel(dev, REL_X, data / 2);
                        input_report_rel(dev, REL_Y, buf[4]);
                        buf[3] = data - data / 2;
                        break;

                case 2:
                        /* Guessing the state of the middle button on 3-button MS-protocol mice - ugly. */
                        if ((sermouse->type == SERIO_MS) && !data && !buf[2] && !((buf[0] & 0xf0) ^ buf[1]))
                                input_report_key(dev, BTN_MIDDLE, !test_bit(BTN_MIDDLE, dev->key));
                        buf[0] = buf[1];

                        data = (signed char) (((buf[1] << 4) & 0xc0) | (data & 0x3f));
                        input_report_rel(dev, REL_X, buf[3]);
                        input_report_rel(dev, REL_Y, data - buf[4]);
                        buf[4] = data / 2;
                        break;

                case 3:

                        switch (sermouse->type) {

                                case SERIO_MS:
                                        sermouse->type = SERIO_MP;
                                        fallthrough;

                                case SERIO_MP:
                                        if ((data >> 2) & 3) break;     /* M++ Wireless Extension packet. */
                                        input_report_key(dev, BTN_MIDDLE, (data >> 5) & 1);
                                        input_report_key(dev, BTN_SIDE,   (data >> 4) & 1);
                                        break;

                                case SERIO_MZP:
                                case SERIO_MZPP:
                                        input_report_key(dev, BTN_SIDE,   (data >> 5) & 1);
                                        fallthrough;

                                case SERIO_MZ:
                                        input_report_key(dev, BTN_MIDDLE, (data >> 4) & 1);
                                        input_report_rel(dev, REL_WHEEL,  (data & 8) - (data & 7));
                                        break;
                        }

                        break;

                case 4:
                case 6: /* MZ++ packet type. We can get these bytes for M++ too but we ignore them later. */
                        buf[1] = (data >> 2) & 0x0f;
                        break;

                case 5:
                case 7: /* Ignore anything besides MZ++ */
                        if (sermouse->type != SERIO_MZPP)
                                break;

                        switch (buf[1]) {

                                case 1: /* Extra mouse info */

                                        input_report_key(dev, BTN_SIDE, (data >> 4) & 1);
                                        input_report_key(dev, BTN_EXTRA, (data >> 5) & 1);
                                        input_report_rel(dev, data & 0x80 ? REL_HWHEEL : REL_WHEEL, (data & 7) - (data & 8));

                                        break;

                                default: /* We don't decode anything else yet. */

                                        printk(KERN_WARNING
                                                "sermouse.c: Received MZ++ packet %x, don't know how to handle.\n", buf[1]);
                                        break;
                        }

                        break;
        }

        input_sync(dev);

        sermouse->count++;
}

/*
 * sermouse_interrupt() handles incoming characters, either gathering them into
 * packets or passing them to the command routine as command output.
 */

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

        if (time_after(jiffies, sermouse->last + HZ/10))
                sermouse->count = 0;

        sermouse->last = jiffies;

        if (sermouse->type > SERIO_SUN)
                sermouse_process_ms(sermouse, data);
        else
                sermouse_process_msc(sermouse, data);

        return IRQ_HANDLED;
}

/*
 * sermouse_disconnect() cleans up after we don't want talk
 * to the mouse anymore.
 */

static void sermouse_disconnect(struct serio *serio)
{
        struct sermouse *sermouse = serio_get_drvdata(serio);

        serio_close(serio);
        serio_set_drvdata(serio, NULL);
        input_unregister_device(sermouse->dev);
        kfree(sermouse);
}

/*
 * sermouse_connect() is a callback form the serio module when
 * an unhandled serio port is found.
 */

static int sermouse_connect(struct serio *serio, struct serio_driver *drv)
{
        struct sermouse *sermouse;
        struct input_dev *input_dev;
        unsigned char c = serio->id.extra;
        int err = -ENOMEM;

        sermouse = kzalloc_obj(*sermouse);
        input_dev = input_allocate_device();
        if (!sermouse || !input_dev)
                goto fail1;

        sermouse->dev = input_dev;
        snprintf(sermouse->phys, sizeof(sermouse->phys), "%s/input0", serio->phys);
        sermouse->type = serio->id.proto;

        input_dev->name = sermouse_protocols[sermouse->type];
        input_dev->phys = sermouse->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor  = sermouse->type;
        input_dev->id.product = c;
        input_dev->id.version = 0x0100;
        input_dev->dev.parent = &serio->dev;

        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
        input_dev->keybit[BIT_WORD(BTN_MOUSE)] = BIT_MASK(BTN_LEFT) |
                BIT_MASK(BTN_RIGHT);
        input_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);

        if (c & 0x01) set_bit(BTN_MIDDLE, input_dev->keybit);
        if (c & 0x02) set_bit(BTN_SIDE, input_dev->keybit);
        if (c & 0x04) set_bit(BTN_EXTRA, input_dev->keybit);
        if (c & 0x10) set_bit(REL_WHEEL, input_dev->relbit);
        if (c & 0x20) set_bit(REL_HWHEEL, input_dev->relbit);

        serio_set_drvdata(serio, sermouse);

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

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

        return 0;

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

static struct serio_device_id sermouse_serio_ids[] = {
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MSC,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_SUN,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MS,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MP,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MZ,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MZP,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_MZPP,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        { 0 }
};

MODULE_DEVICE_TABLE(serio, sermouse_serio_ids);

static struct serio_driver sermouse_drv = {
        .driver         = {
                .name   = "sermouse",
        },
        .description    = DRIVER_DESC,
        .id_table       = sermouse_serio_ids,
        .interrupt      = sermouse_interrupt,
        .connect        = sermouse_connect,
        .disconnect     = sermouse_disconnect,
};

module_serio_driver(sermouse_drv);