tsc40.c

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/*
 * TSC-40 serial touchscreen driver. It should be compatible with
 * TSC-10 and 25.
 *
 * Author: Sebastian Andrzej Siewior <[email protected]>
 * License: GPLv2 as published by the FSF.
 */

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

#define PACKET_LENGTH  5
struct tsc_ser {
    struct input_dev *dev;
    struct serio *serio;
    u32 idx;
    unsigned char data[PACKET_LENGTH];
    char phys[32];
};

static void tsc_process_data(struct tsc_ser *ptsc)
{
    struct input_dev *dev = ptsc->dev;
    u8 *data = ptsc->data;
    u32 x;
    u32 y;

    x = ((data[1] & 0x03) << 8) | data[2];
    y = ((data[3] & 0x03) << 8) | data[4];

    input_report_abs(dev, ABS_X, x);
    input_report_abs(dev, ABS_Y, y);
    input_report_key(dev, BTN_TOUCH, 1);

    input_sync(dev);
}

static irqreturn_t tsc_interrupt(struct serio *serio,
        unsigned char data, unsigned int flags)
{
    struct tsc_ser *ptsc = serio_get_drvdata(serio);
    struct input_dev *dev = ptsc->dev;

    ptsc->data[ptsc->idx] = data;
    switch (ptsc->idx++) {
    case 0:
        if (unlikely((data & 0x3e) != 0x10)) {
            dev_dbg(&serio->dev,
                "unsynchronized packet start (0x%02x)\n", data);
            ptsc->idx = 0;
        } else if (!(data & 0x01)) {
            input_report_key(dev, BTN_TOUCH, 0);
            input_sync(dev);
            ptsc->idx = 0;
        }
        break;

    case 1:
    case 3:
        if (unlikely(data & 0xfc)) {
            dev_dbg(&serio->dev,
                "unsynchronized data 0x%02x at offset %d\n",
                data, ptsc->idx - 1);
            ptsc->idx = 0;
        }
        break;

    case 4:
        tsc_process_data(ptsc);
        ptsc->idx = 0;
        break;
    }

    return IRQ_HANDLED;
}

static int tsc_connect(struct serio *serio, struct serio_driver *drv)
{
    struct tsc_ser *ptsc;
    struct input_dev *input_dev;
    int error;

    ptsc = kzalloc(sizeof(struct tsc_ser), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!ptsc || !input_dev) {
        error = -ENOMEM;
        goto fail1;
    }

    ptsc->serio = serio;
    ptsc->dev = input_dev;
    snprintf(ptsc->phys, sizeof(ptsc->phys), "%s/input0", serio->phys);

    input_dev->name = "TSC-10/25/40 Serial TouchScreen";
    input_dev->phys = ptsc->phys;
    input_dev->id.bustype = BUS_RS232;
    input_dev->id.vendor = SERIO_TSC40;
    input_dev->id.product = 40;
    input_dev->id.version = 0x0001;
    input_dev->dev.parent = &serio->dev;

    input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    __set_bit(BTN_TOUCH, input_dev->keybit);
    input_set_abs_params(ptsc->dev, ABS_X, 0, 0x3ff, 0, 0);
    input_set_abs_params(ptsc->dev, ABS_Y, 0, 0x3ff, 0, 0);

    serio_set_drvdata(serio, ptsc);

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

    error = input_register_device(ptsc->dev);
    if (error)
        goto fail3;

    return 0;

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

static void tsc_disconnect(struct serio *serio)
{
    struct tsc_ser *ptsc = serio_get_drvdata(serio);

    serio_close(serio);

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

    serio_set_drvdata(serio, NULL);
}

static struct serio_device_id tsc_serio_ids[] = {
    {
        .type   = SERIO_RS232,
        .proto  = SERIO_TSC40,
        .id     = SERIO_ANY,
        .extra  = SERIO_ANY,
    },
    { 0 }
};
MODULE_DEVICE_TABLE(serio, tsc_serio_ids);

#define DRIVER_DESC    "TSC-10/25/40 serial touchscreen driver"

static struct serio_driver tsc_drv = {
    .driver = {
        .name   = "tsc40",
    },
    .description    = DRIVER_DESC,
    .id_table   = tsc_serio_ids,
    .interrupt      = tsc_interrupt,
    .connect    = tsc_connect,
    .disconnect     = tsc_disconnect,
};

module_serio_driver(tsc_drv);

MODULE_AUTHOR("Sebastian Andrzej Siewior <[email protected]>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");