fujitsu_ts.c

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/*
 * Fujitsu serial touchscreen driver
 *
 * Copyright (c) Dmitry Torokhov <[email protected]>
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#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/init.h>

#define DRIVER_DESC "Fujitsu serial touchscreen driver"

MODULE_AUTHOR("Dmitry Torokhov <[email protected]>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define FUJITSU_LENGTH 5

/*
 * Per-touchscreen data.
 */
struct fujitsu {
    struct input_dev *dev;
    struct serio *serio;
    int idx;
    unsigned char data[FUJITSU_LENGTH];
    char phys[32];
};

/*
 * Decode serial data (5 bytes per packet)
 * First byte
 * 1 C 0 0 R S S S
 * Where C is 1 while in calibration mode (which we don't use)
 * R is 1 when no coordinate corection was done.
 * S are button state
 */
static irqreturn_t fujitsu_interrupt(struct serio *serio,
                     unsigned char data, unsigned int flags)
{
    struct fujitsu *fujitsu = serio_get_drvdata(serio);
    struct input_dev *dev = fujitsu->dev;

    if (fujitsu->idx == 0) {
        /* resync skip until start of frame */
        if ((data & 0xf0) != 0x80)
            return IRQ_HANDLED;
    } else {
        /* resync skip garbage */
        if (data & 0x80) {
            fujitsu->idx = 0;
            return IRQ_HANDLED;
        }
    }

    fujitsu->data[fujitsu->idx++] = data;
    if (fujitsu->idx == FUJITSU_LENGTH) {
        input_report_abs(dev, ABS_X,
                 (fujitsu->data[2] << 7) | fujitsu->data[1]);
        input_report_abs(dev, ABS_Y,
                 (fujitsu->data[4] << 7) | fujitsu->data[3]);
        input_report_key(dev, BTN_TOUCH,
                 (fujitsu->data[0] & 0x03) != 2);
        input_sync(dev);
        fujitsu->idx = 0;
    }

    return IRQ_HANDLED;
}

/*
 * fujitsu_disconnect() is the opposite of fujitsu_connect()
 */
static void fujitsu_disconnect(struct serio *serio)
{
    struct fujitsu *fujitsu = serio_get_drvdata(serio);

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

/*
 * fujitsu_connect() is the routine that is called when someone adds a
 * new serio device that supports the Fujitsu protocol and registers it
 * as input device.
 */
static int fujitsu_connect(struct serio *serio, struct serio_driver *drv)
{
    struct fujitsu *fujitsu;
    struct input_dev *input_dev;
    int err;

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

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

    input_dev->name = "Fujitsu Serial Touchscreen";
    input_dev->phys = fujitsu->phys;
    input_dev->id.bustype = BUS_RS232;
    input_dev->id.vendor = SERIO_FUJITSU;
    input_dev->id.product = 0;
    input_dev->id.version = 0x0100;
    input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

    input_set_abs_params(input_dev, ABS_X, 0, 4096, 0, 0);
    input_set_abs_params(input_dev, ABS_Y, 0, 4096, 0, 0);
    serio_set_drvdata(serio, fujitsu);

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

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

    return 0;

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

/*
 * The serio driver structure.
 */
static struct serio_device_id fujitsu_serio_ids[] = {
    {
        .type   = SERIO_RS232,
        .proto  = SERIO_FUJITSU,
        .id = SERIO_ANY,
        .extra  = SERIO_ANY,
    },
    { 0 }
};

MODULE_DEVICE_TABLE(serio, fujitsu_serio_ids);

static struct serio_driver fujitsu_drv = {
    .driver     = {
        .name   = "fujitsu_ts",
    },
    .description    = DRIVER_DESC,
    .id_table   = fujitsu_serio_ids,
    .interrupt  = fujitsu_interrupt,
    .connect    = fujitsu_connect,
    .disconnect = fujitsu_disconnect,
};

module_serio_driver(fujitsu_drv);