eeti_ts.c

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/*
 * Touch Screen driver for EETI's I2C connected touch screen panels
 *   Copyright (c) 2009 Daniel Mack <[email protected]>
 *
 * See EETI's software guide for the protocol specification:
 *   http://home.eeti.com.tw/web20/eg/guide.htm
 *
 * Based on migor_ts.c
 *   Copyright (c) 2008 Magnus Damm
 *   Copyright (c) 2007 Ujjwal Pande <[email protected]>
 *
 * This file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU  General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This file is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/timer.h>
#include <linux/gpio.h>
#include <linux/input/eeti_ts.h>
#include <linux/slab.h>

static bool flip_x;
module_param(flip_x, bool, 0644);
MODULE_PARM_DESC(flip_x, "flip x coordinate");

static bool flip_y;
module_param(flip_y, bool, 0644);
MODULE_PARM_DESC(flip_y, "flip y coordinate");

struct eeti_ts_priv {
    struct i2c_client *client;
    struct input_dev *input;
    struct work_struct work;
    struct mutex mutex;
    int irq_gpio, irq, irq_active_high;
};

#define EETI_TS_BITDEPTH    (11)
#define EETI_MAXVAL     ((1 << (EETI_TS_BITDEPTH + 1)) - 1)

#define REPORT_BIT_PRESSED  (1 << 0)
#define REPORT_BIT_AD0      (1 << 1)
#define REPORT_BIT_AD1      (1 << 2)
#define REPORT_BIT_HAS_PRESSURE (1 << 6)
#define REPORT_RES_BITS(v)  (((v) >> 1) + EETI_TS_BITDEPTH)

static inline int eeti_ts_irq_active(struct eeti_ts_priv *priv)
{
    return gpio_get_value(priv->irq_gpio) == priv->irq_active_high;
}

static void eeti_ts_read(struct work_struct *work)
{
    char buf[6];
    unsigned int x, y, res, pressed, to = 100;
    struct eeti_ts_priv *priv =
        container_of(work, struct eeti_ts_priv, work);

    mutex_lock(&priv->mutex);

    while (eeti_ts_irq_active(priv) && --to)
        i2c_master_recv(priv->client, buf, sizeof(buf));

    if (!to) {
        dev_err(&priv->client->dev,
            "unable to clear IRQ - line stuck?\n");
        goto out;
    }

    /* drop non-report packets */
    if (!(buf[0] & 0x80))
        goto out;

    pressed = buf[0] & REPORT_BIT_PRESSED;
    res = REPORT_RES_BITS(buf[0] & (REPORT_BIT_AD0 | REPORT_BIT_AD1));
    x = buf[2] | (buf[1] << 8);
    y = buf[4] | (buf[3] << 8);

    /* fix the range to 11 bits */
    x >>= res - EETI_TS_BITDEPTH;
    y >>= res - EETI_TS_BITDEPTH;

    if (flip_x)
        x = EETI_MAXVAL - x;

    if (flip_y)
        y = EETI_MAXVAL - y;

    if (buf[0] & REPORT_BIT_HAS_PRESSURE)
        input_report_abs(priv->input, ABS_PRESSURE, buf[5]);

    input_report_abs(priv->input, ABS_X, x);
    input_report_abs(priv->input, ABS_Y, y);
    input_report_key(priv->input, BTN_TOUCH, !!pressed);
    input_sync(priv->input);

out:
    mutex_unlock(&priv->mutex);
}

static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
{
    struct eeti_ts_priv *priv = dev_id;

     /* postpone I2C transactions as we are atomic */
    schedule_work(&priv->work);

    return IRQ_HANDLED;
}

static void eeti_ts_start(struct eeti_ts_priv *priv)
{
    enable_irq(priv->irq);

    /* Read the events once to arm the IRQ */
    eeti_ts_read(&priv->work);
}

static void eeti_ts_stop(struct eeti_ts_priv *priv)
{
    disable_irq(priv->irq);
    cancel_work_sync(&priv->work);
}

static int eeti_ts_open(struct input_dev *dev)
{
    struct eeti_ts_priv *priv = input_get_drvdata(dev);

    eeti_ts_start(priv);

    return 0;
}

static void eeti_ts_close(struct input_dev *dev)
{
    struct eeti_ts_priv *priv = input_get_drvdata(dev);

    eeti_ts_stop(priv);
}

static int __devinit eeti_ts_probe(struct i2c_client *client,
                   const struct i2c_device_id *idp)
{
    struct eeti_ts_platform_data *pdata = client->dev.platform_data;
    struct eeti_ts_priv *priv;
    struct input_dev *input;
    unsigned int irq_flags;
    int err = -ENOMEM;

    /*
     * In contrast to what's described in the datasheet, there seems
     * to be no way of probing the presence of that device using I2C
     * commands. So we need to blindly believe it is there, and wait
     * for interrupts to occur.
     */

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (!priv) {
        dev_err(&client->dev, "failed to allocate driver data\n");
        goto err0;
    }

    mutex_init(&priv->mutex);
    input = input_allocate_device();

    if (!input) {
        dev_err(&client->dev, "Failed to allocate input device.\n");
        goto err1;
    }

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

    input_set_abs_params(input, ABS_X, 0, EETI_MAXVAL, 0, 0);
    input_set_abs_params(input, ABS_Y, 0, EETI_MAXVAL, 0, 0);
    input_set_abs_params(input, ABS_PRESSURE, 0, 0xff, 0, 0);

    input->name = client->name;
    input->id.bustype = BUS_I2C;
    input->dev.parent = &client->dev;
    input->open = eeti_ts_open;
    input->close = eeti_ts_close;

    priv->client = client;
    priv->input = input;
    priv->irq_gpio = pdata->irq_gpio;
    priv->irq = gpio_to_irq(pdata->irq_gpio);

    err = gpio_request_one(pdata->irq_gpio, GPIOF_IN, client->name);
    if (err < 0)
        goto err1;

    if (pdata)
        priv->irq_active_high = pdata->irq_active_high;

    irq_flags = priv->irq_active_high ?
        IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;

    INIT_WORK(&priv->work, eeti_ts_read);
    i2c_set_clientdata(client, priv);
    input_set_drvdata(input, priv);

    err = input_register_device(input);
    if (err)
        goto err2;

    err = request_irq(priv->irq, eeti_ts_isr, irq_flags,
              client->name, priv);
    if (err) {
        dev_err(&client->dev, "Unable to request touchscreen IRQ.\n");
        goto err3;
    }

    /*
     * Disable the device for now. It will be enabled once the
     * input device is opened.
     */
    eeti_ts_stop(priv);

    device_init_wakeup(&client->dev, 0);
    return 0;

err3:
    input_unregister_device(input);
    input = NULL; /* so we dont try to free it below */
err2:
    gpio_free(pdata->irq_gpio);
err1:
    input_free_device(input);
    kfree(priv);
err0:
    return err;
}

static int __devexit eeti_ts_remove(struct i2c_client *client)
{
    struct eeti_ts_priv *priv = i2c_get_clientdata(client);

    free_irq(priv->irq, priv);
    /*
     * eeti_ts_stop() leaves IRQ disabled. We need to re-enable it
     * so that device still works if we reload the driver.
     */
    enable_irq(priv->irq);

    input_unregister_device(priv->input);
    kfree(priv);

    return 0;
}

#ifdef CONFIG_PM
static int eeti_ts_suspend(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct eeti_ts_priv *priv = i2c_get_clientdata(client);
    struct input_dev *input_dev = priv->input;

    mutex_lock(&input_dev->mutex);

    if (input_dev->users)
        eeti_ts_stop(priv);

    mutex_unlock(&input_dev->mutex);

    if (device_may_wakeup(&client->dev))
        enable_irq_wake(priv->irq);

    return 0;
}

static int eeti_ts_resume(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct eeti_ts_priv *priv = i2c_get_clientdata(client);
    struct input_dev *input_dev = priv->input;

    if (device_may_wakeup(&client->dev))
        disable_irq_wake(priv->irq);

    mutex_lock(&input_dev->mutex);

    if (input_dev->users)
        eeti_ts_start(priv);

    mutex_unlock(&input_dev->mutex);

    return 0;
}

static SIMPLE_DEV_PM_OPS(eeti_ts_pm, eeti_ts_suspend, eeti_ts_resume);
#endif

static const struct i2c_device_id eeti_ts_id[] = {
    { "eeti_ts", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, eeti_ts_id);

static struct i2c_driver eeti_ts_driver = {
    .driver = {
        .name = "eeti_ts",
#ifdef CONFIG_PM
        .pm = &eeti_ts_pm,
#endif
    },
    .probe = eeti_ts_probe,
    .remove = __devexit_p(eeti_ts_remove),
    .id_table = eeti_ts_id,
};

module_i2c_driver(eeti_ts_driver);

MODULE_DESCRIPTION("EETI Touchscreen driver");
MODULE_AUTHOR("Daniel Mack <[email protected]>");
MODULE_LICENSE("GPL");