tsc2007.c

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/*
 * drivers/input/touchscreen/tsc2007.c
 *
 * Copyright (c) 2008 MtekVision Co., Ltd.
 *  Kwangwoo Lee <[email protected]>
 *
 * Using code from:
 *  - ads7846.c
 *  Copyright (c) 2005 David Brownell
 *  Copyright (c) 2006 Nokia Corporation
 *  - corgi_ts.c
 *  Copyright (C) 2004-2005 Richard Purdie
 *  - omap_ts.[hc], ads7846.h, ts_osk.c
 *  Copyright (C) 2002 MontaVista Software
 *  Copyright (C) 2004 Texas Instruments
 *  Copyright (C) 2005 Dirk Behme
 *
 *  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/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/i2c/tsc2007.h>

#define TSC2007_MEASURE_TEMP0       (0x0 << 4)
#define TSC2007_MEASURE_AUX     (0x2 << 4)
#define TSC2007_MEASURE_TEMP1       (0x4 << 4)
#define TSC2007_ACTIVATE_XN     (0x8 << 4)
#define TSC2007_ACTIVATE_YN     (0x9 << 4)
#define TSC2007_ACTIVATE_YP_XN      (0xa << 4)
#define TSC2007_SETUP           (0xb << 4)
#define TSC2007_MEASURE_X       (0xc << 4)
#define TSC2007_MEASURE_Y       (0xd << 4)
#define TSC2007_MEASURE_Z1      (0xe << 4)
#define TSC2007_MEASURE_Z2      (0xf << 4)

#define TSC2007_POWER_OFF_IRQ_EN    (0x0 << 2)
#define TSC2007_ADC_ON_IRQ_DIS0     (0x1 << 2)
#define TSC2007_ADC_OFF_IRQ_EN      (0x2 << 2)
#define TSC2007_ADC_ON_IRQ_DIS1     (0x3 << 2)

#define TSC2007_12BIT           (0x0 << 1)
#define TSC2007_8BIT            (0x1 << 1)

#define MAX_12BIT           ((1 << 12) - 1)

#define ADC_ON_12BIT    (TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)

#define READ_Y      (ADC_ON_12BIT | TSC2007_MEASURE_Y)
#define READ_Z1     (ADC_ON_12BIT | TSC2007_MEASURE_Z1)
#define READ_Z2     (ADC_ON_12BIT | TSC2007_MEASURE_Z2)
#define READ_X      (ADC_ON_12BIT | TSC2007_MEASURE_X)
#define PWRDOWN     (TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)

struct ts_event {
    u16 x;
    u16 y;
    u16 z1, z2;
};

struct tsc2007 {
    struct input_dev    *input;
    char            phys[32];

    struct i2c_client   *client;

    u16         model;
    u16         x_plate_ohms;
    u16         max_rt;
    unsigned long       poll_delay;
    unsigned long       poll_period;

    int         irq;

    wait_queue_head_t   wait;
    bool            stopped;

    int         (*get_pendown_state)(void);
    void            (*clear_penirq)(void);
};

static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
{
    s32 data;
    u16 val;

    data = i2c_smbus_read_word_data(tsc->client, cmd);
    if (data < 0) {
        dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
        return data;
    }

    /* The protocol and raw data format from i2c interface:
     * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
     * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
     */
    val = swab16(data) >> 4;

    dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);

    return val;
}

static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
{
    /* y- still on; turn on only y+ (and ADC) */
    tc->y = tsc2007_xfer(tsc, READ_Y);

    /* turn y- off, x+ on, then leave in lowpower */
    tc->x = tsc2007_xfer(tsc, READ_X);

    /* turn y+ off, x- on; we'll use formula #1 */
    tc->z1 = tsc2007_xfer(tsc, READ_Z1);
    tc->z2 = tsc2007_xfer(tsc, READ_Z2);

    /* Prepare for next touch reading - power down ADC, enable PENIRQ */
    tsc2007_xfer(tsc, PWRDOWN);
}

static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
{
    u32 rt = 0;

    /* range filtering */
    if (tc->x == MAX_12BIT)
        tc->x = 0;

    if (likely(tc->x && tc->z1)) {
        /* compute touch pressure resistance using equation #1 */
        rt = tc->z2 - tc->z1;
        rt *= tc->x;
        rt *= tsc->x_plate_ohms;
        rt /= tc->z1;
        rt = (rt + 2047) >> 12;
    }

    return rt;
}

static bool tsc2007_is_pen_down(struct tsc2007 *ts)
{
    /*
     * NOTE: We can't rely on the pressure to determine the pen down
     * state, even though this controller has a pressure sensor.
     * The pressure value can fluctuate for quite a while after
     * lifting the pen and in some cases may not even settle at the
     * expected value.
     *
     * The only safe way to check for the pen up condition is in the
     * work function by reading the pen signal state (it's a GPIO
     * and IRQ). Unfortunately such callback is not always available,
     * in that case we assume that the pen is down and expect caller
     * to fall back on the pressure reading.
     */

    if (!ts->get_pendown_state)
        return true;

    return ts->get_pendown_state();
}

static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
{
    struct tsc2007 *ts = handle;
    struct input_dev *input = ts->input;
    struct ts_event tc;
    u32 rt;

    while (!ts->stopped && tsc2007_is_pen_down(ts)) {

        /* pen is down, continue with the measurement */
        tsc2007_read_values(ts, &tc);

        rt = tsc2007_calculate_pressure(ts, &tc);

        if (rt == 0 && !ts->get_pendown_state) {
            /*
             * If pressure reported is 0 and we don't have
             * callback to check pendown state, we have to
             * assume that pen was lifted up.
             */
            break;
        }

        if (rt <= ts->max_rt) {
            dev_dbg(&ts->client->dev,
                "DOWN point(%4d,%4d), pressure (%4u)\n",
                tc.x, tc.y, rt);

            input_report_key(input, BTN_TOUCH, 1);
            input_report_abs(input, ABS_X, tc.x);
            input_report_abs(input, ABS_Y, tc.y);
            input_report_abs(input, ABS_PRESSURE, rt);

            input_sync(input);

        } else {
            /*
             * Sample found inconsistent by debouncing or pressure is
             * beyond the maximum. Don't report it to user space,
             * repeat at least once more the measurement.
             */
            dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
        }

        wait_event_timeout(ts->wait, ts->stopped,
                   msecs_to_jiffies(ts->poll_period));
    }

    dev_dbg(&ts->client->dev, "UP\n");

    input_report_key(input, BTN_TOUCH, 0);
    input_report_abs(input, ABS_PRESSURE, 0);
    input_sync(input);

    if (ts->clear_penirq)
        ts->clear_penirq();

    return IRQ_HANDLED;
}

static irqreturn_t tsc2007_hard_irq(int irq, void *handle)
{
    struct tsc2007 *ts = handle;

    if (!ts->get_pendown_state || likely(ts->get_pendown_state()))
        return IRQ_WAKE_THREAD;

    if (ts->clear_penirq)
        ts->clear_penirq();

    return IRQ_HANDLED;
}

static void tsc2007_stop(struct tsc2007 *ts)
{
    ts->stopped = true;
    mb();
    wake_up(&ts->wait);

    disable_irq(ts->irq);
}

static int tsc2007_open(struct input_dev *input_dev)
{
    struct tsc2007 *ts = input_get_drvdata(input_dev);
    int err;

    ts->stopped = false;
    mb();

    enable_irq(ts->irq);

    /* Prepare for touch readings - power down ADC and enable PENIRQ */
    err = tsc2007_xfer(ts, PWRDOWN);
    if (err < 0) {
        tsc2007_stop(ts);
        return err;
    }

    return 0;
}

static void tsc2007_close(struct input_dev *input_dev)
{
    struct tsc2007 *ts = input_get_drvdata(input_dev);

    tsc2007_stop(ts);
}

static int __devinit tsc2007_probe(struct i2c_client *client,
                   const struct i2c_device_id *id)
{
    struct tsc2007 *ts;
    struct tsc2007_platform_data *pdata = client->dev.platform_data;
    struct input_dev *input_dev;
    int err;

    if (!pdata) {
        dev_err(&client->dev, "platform data is required!\n");
        return -EINVAL;
    }

    if (!i2c_check_functionality(client->adapter,
                     I2C_FUNC_SMBUS_READ_WORD_DATA))
        return -EIO;

    ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!ts || !input_dev) {
        err = -ENOMEM;
        goto err_free_mem;
    }

    ts->client = client;
    ts->irq = client->irq;
    ts->input = input_dev;
    init_waitqueue_head(&ts->wait);

    ts->model             = pdata->model;
    ts->x_plate_ohms      = pdata->x_plate_ohms;
    ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
    ts->poll_delay        = pdata->poll_delay ? : 1;
    ts->poll_period       = pdata->poll_period ? : 1;
    ts->get_pendown_state = pdata->get_pendown_state;
    ts->clear_penirq      = pdata->clear_penirq;

    if (pdata->x_plate_ohms == 0) {
        dev_err(&client->dev, "x_plate_ohms is not set up in platform data");
        err = -EINVAL;
        goto err_free_mem;
    }

    snprintf(ts->phys, sizeof(ts->phys),
         "%s/input0", dev_name(&client->dev));

    input_dev->name = "TSC2007 Touchscreen";
    input_dev->phys = ts->phys;
    input_dev->id.bustype = BUS_I2C;

    input_dev->open = tsc2007_open;
    input_dev->close = tsc2007_close;

    input_set_drvdata(input_dev, ts);

    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, MAX_12BIT, pdata->fuzzx, 0);
    input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, pdata->fuzzy, 0);
    input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
            pdata->fuzzz, 0);

    if (pdata->init_platform_hw)
        pdata->init_platform_hw();

    err = request_threaded_irq(ts->irq, tsc2007_hard_irq, tsc2007_soft_irq,
                   IRQF_ONESHOT, client->dev.driver->name, ts);
    if (err < 0) {
        dev_err(&client->dev, "irq %d busy?\n", ts->irq);
        goto err_free_mem;
    }

    tsc2007_stop(ts);

    err = input_register_device(input_dev);
    if (err)
        goto err_free_irq;

    i2c_set_clientdata(client, ts);

    return 0;

 err_free_irq:
    free_irq(ts->irq, ts);
    if (pdata->exit_platform_hw)
        pdata->exit_platform_hw();
 err_free_mem:
    input_free_device(input_dev);
    kfree(ts);
    return err;
}

static int __devexit tsc2007_remove(struct i2c_client *client)
{
    struct tsc2007  *ts = i2c_get_clientdata(client);
    struct tsc2007_platform_data *pdata = client->dev.platform_data;

    free_irq(ts->irq, ts);

    if (pdata->exit_platform_hw)
        pdata->exit_platform_hw();

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

    return 0;
}

static const struct i2c_device_id tsc2007_idtable[] = {
    { "tsc2007", 0 },
    { }
};

MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);

static struct i2c_driver tsc2007_driver = {
    .driver = {
        .owner  = THIS_MODULE,
        .name   = "tsc2007"
    },
    .id_table   = tsc2007_idtable,
    .probe      = tsc2007_probe,
    .remove     = __devexit_p(tsc2007_remove),
};

module_i2c_driver(tsc2007_driver);

MODULE_AUTHOR("Kwangwoo Lee <[email protected]>");
MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
MODULE_LICENSE("GPL");