ad7877.c

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/*
 * Copyright (C) 2006-2008 Michael Hennerich, Analog Devices Inc.
 *
 * Description: AD7877 based touchscreen, sensor (ADCs), DAC and GPIO driver
 * Based on:    ads7846.c
 *
 * Bugs:        Enter bugs at http://blackfin.uclinux.org/
 *
 * This program 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 program 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 program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * History:
 * Copyright (c) 2005 David Brownell
 * Copyright (c) 2006 Nokia Corporation
 * Various changes: Imre Deak <[email protected]>
 *
 * Using code from:
 *  - 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
 */


#include <linux/device.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/spi/ad7877.h>
#include <linux/module.h>
#include <asm/irq.h>

#define TS_PEN_UP_TIMEOUT   msecs_to_jiffies(100)

#define MAX_SPI_FREQ_HZ         20000000
#define MAX_12BIT           ((1<<12)-1)

#define AD7877_REG_ZEROS            0
#define AD7877_REG_CTRL1            1
#define AD7877_REG_CTRL2            2
#define AD7877_REG_ALERT            3
#define AD7877_REG_AUX1HIGH         4
#define AD7877_REG_AUX1LOW          5
#define AD7877_REG_BAT1HIGH         6
#define AD7877_REG_BAT1LOW          7
#define AD7877_REG_BAT2HIGH         8
#define AD7877_REG_BAT2LOW          9
#define AD7877_REG_TEMP1HIGH            10
#define AD7877_REG_TEMP1LOW         11
#define AD7877_REG_SEQ0             12
#define AD7877_REG_SEQ1             13
#define AD7877_REG_DAC              14
#define AD7877_REG_NONE1            15
#define AD7877_REG_EXTWRITE         15
#define AD7877_REG_XPLUS            16
#define AD7877_REG_YPLUS            17
#define AD7877_REG_Z2               18
#define AD7877_REG_aux1             19
#define AD7877_REG_aux2             20
#define AD7877_REG_aux3             21
#define AD7877_REG_bat1             22
#define AD7877_REG_bat2             23
#define AD7877_REG_temp1            24
#define AD7877_REG_temp2            25
#define AD7877_REG_Z1               26
#define AD7877_REG_GPIOCTRL1            27
#define AD7877_REG_GPIOCTRL2            28
#define AD7877_REG_GPIODATA         29
#define AD7877_REG_NONE2            30
#define AD7877_REG_NONE3            31

#define AD7877_SEQ_YPLUS_BIT            (1<<11)
#define AD7877_SEQ_XPLUS_BIT            (1<<10)
#define AD7877_SEQ_Z2_BIT           (1<<9)
#define AD7877_SEQ_AUX1_BIT         (1<<8)
#define AD7877_SEQ_AUX2_BIT         (1<<7)
#define AD7877_SEQ_AUX3_BIT         (1<<6)
#define AD7877_SEQ_BAT1_BIT         (1<<5)
#define AD7877_SEQ_BAT2_BIT         (1<<4)
#define AD7877_SEQ_TEMP1_BIT            (1<<3)
#define AD7877_SEQ_TEMP2_BIT            (1<<2)
#define AD7877_SEQ_Z1_BIT           (1<<1)

enum {
    AD7877_SEQ_YPOS  = 0,
    AD7877_SEQ_XPOS  = 1,
    AD7877_SEQ_Z2    = 2,
    AD7877_SEQ_AUX1  = 3,
    AD7877_SEQ_AUX2  = 4,
    AD7877_SEQ_AUX3  = 5,
    AD7877_SEQ_BAT1  = 6,
    AD7877_SEQ_BAT2  = 7,
    AD7877_SEQ_TEMP1 = 8,
    AD7877_SEQ_TEMP2 = 9,
    AD7877_SEQ_Z1    = 10,
    AD7877_NR_SENSE  = 11,
};

/* DAC Register Default RANGE 0 to Vcc, Volatge Mode, DAC On */
#define AD7877_DAC_CONF         0x1

/* If gpio3 is set AUX3/GPIO3 acts as GPIO Output */
#define AD7877_EXTW_GPIO_3_CONF     0x1C4
#define AD7877_EXTW_GPIO_DATA       0x200

/* Control REG 2 */
#define AD7877_TMR(x)           ((x & 0x3) << 0)
#define AD7877_REF(x)           ((x & 0x1) << 2)
#define AD7877_POL(x)           ((x & 0x1) << 3)
#define AD7877_FCD(x)           ((x & 0x3) << 4)
#define AD7877_PM(x)            ((x & 0x3) << 6)
#define AD7877_ACQ(x)           ((x & 0x3) << 8)
#define AD7877_AVG(x)           ((x & 0x3) << 10)

/* Control REG 1 */
#define AD7877_SER          (1 << 11)   /* non-differential */
#define AD7877_DFR          (0 << 11)   /* differential */

#define AD7877_MODE_NOC  (0)    /* Do not convert */
#define AD7877_MODE_SCC  (1)    /* Single channel conversion */
#define AD7877_MODE_SEQ0 (2)    /* Sequence 0 in Slave Mode */
#define AD7877_MODE_SEQ1 (3)    /* Sequence 1 in Master Mode */

#define AD7877_CHANADD(x)       ((x&0xF)<<7)
#define AD7877_READADD(x)       ((x)<<2)
#define AD7877_WRITEADD(x)      ((x)<<12)

#define AD7877_READ_CHAN(x) (AD7877_WRITEADD(AD7877_REG_CTRL1) | AD7877_SER | \
        AD7877_MODE_SCC | AD7877_CHANADD(AD7877_REG_ ## x) | \
        AD7877_READADD(AD7877_REG_ ## x))

#define AD7877_MM_SEQUENCE (AD7877_SEQ_YPLUS_BIT | AD7877_SEQ_XPLUS_BIT | \
        AD7877_SEQ_Z2_BIT | AD7877_SEQ_Z1_BIT)

/*
 * Non-touchscreen sensors only use single-ended conversions.
 */

struct ser_req {
    u16         reset;
    u16         ref_on;
    u16         command;
    struct spi_message  msg;
    struct spi_transfer xfer[6];

    /*
     * DMA (thus cache coherency maintenance) requires the
     * transfer buffers to live in their own cache lines.
     */
    u16 sample ____cacheline_aligned;
};

struct ad7877 {
    struct input_dev    *input;
    char            phys[32];

    struct spi_device   *spi;
    u16         model;
    u16         vref_delay_usecs;
    u16         x_plate_ohms;
    u16         pressure_max;

    u16         cmd_crtl1;
    u16         cmd_crtl2;
    u16         cmd_dummy;
    u16         dac;

    u8          stopacq_polarity;
    u8          first_conversion_delay;
    u8          acquisition_time;
    u8          averaging;
    u8          pen_down_acc_interval;

    struct spi_transfer xfer[AD7877_NR_SENSE + 2];
    struct spi_message  msg;

    struct mutex        mutex;
    bool            disabled;   /* P: mutex */
    bool            gpio3;      /* P: mutex */
    bool            gpio4;      /* P: mutex */

    spinlock_t      lock;
    struct timer_list   timer;      /* P: lock */

    /*
     * DMA (thus cache coherency maintenance) requires the
     * transfer buffers to live in their own cache lines.
     */
    u16 conversion_data[AD7877_NR_SENSE] ____cacheline_aligned;
};

static bool gpio3;
module_param(gpio3, bool, 0);
MODULE_PARM_DESC(gpio3, "If gpio3 is set to 1 AUX3 acts as GPIO3");

/*
 * ad7877_read/write are only used for initial setup and for sysfs controls.
 * The main traffic is done using spi_async() in the interrupt handler.
 */

static int ad7877_read(struct spi_device *spi, u16 reg)
{
    struct ser_req *req;
    int status, ret;

    req = kzalloc(sizeof *req, GFP_KERNEL);
    if (!req)
        return -ENOMEM;

    spi_message_init(&req->msg);

    req->command = (u16) (AD7877_WRITEADD(AD7877_REG_CTRL1) |
            AD7877_READADD(reg));
    req->xfer[0].tx_buf = &req->command;
    req->xfer[0].len = 2;
    req->xfer[0].cs_change = 1;

    req->xfer[1].rx_buf = &req->sample;
    req->xfer[1].len = 2;

    spi_message_add_tail(&req->xfer[0], &req->msg);
    spi_message_add_tail(&req->xfer[1], &req->msg);

    status = spi_sync(spi, &req->msg);
    ret = status ? : req->sample;

    kfree(req);

    return ret;
}

static int ad7877_write(struct spi_device *spi, u16 reg, u16 val)
{
    struct ser_req *req;
    int status;

    req = kzalloc(sizeof *req, GFP_KERNEL);
    if (!req)
        return -ENOMEM;

    spi_message_init(&req->msg);

    req->command = (u16) (AD7877_WRITEADD(reg) | (val & MAX_12BIT));
    req->xfer[0].tx_buf = &req->command;
    req->xfer[0].len = 2;

    spi_message_add_tail(&req->xfer[0], &req->msg);

    status = spi_sync(spi, &req->msg);

    kfree(req);

    return status;
}

static int ad7877_read_adc(struct spi_device *spi, unsigned command)
{
    struct ad7877 *ts = dev_get_drvdata(&spi->dev);
    struct ser_req *req;
    int status;
    int sample;
    int i;

    req = kzalloc(sizeof *req, GFP_KERNEL);
    if (!req)
        return -ENOMEM;

    spi_message_init(&req->msg);

    /* activate reference, so it has time to settle; */
    req->ref_on = AD7877_WRITEADD(AD7877_REG_CTRL2) |
             AD7877_POL(ts->stopacq_polarity) |
             AD7877_AVG(0) | AD7877_PM(2) | AD7877_TMR(0) |
             AD7877_ACQ(ts->acquisition_time) | AD7877_FCD(0);

    req->reset = AD7877_WRITEADD(AD7877_REG_CTRL1) | AD7877_MODE_NOC;

    req->command = (u16) command;

    req->xfer[0].tx_buf = &req->reset;
    req->xfer[0].len = 2;
    req->xfer[0].cs_change = 1;

    req->xfer[1].tx_buf = &req->ref_on;
    req->xfer[1].len = 2;
    req->xfer[1].delay_usecs = ts->vref_delay_usecs;
    req->xfer[1].cs_change = 1;

    req->xfer[2].tx_buf = &req->command;
    req->xfer[2].len = 2;
    req->xfer[2].delay_usecs = ts->vref_delay_usecs;
    req->xfer[2].cs_change = 1;

    req->xfer[3].rx_buf = &req->sample;
    req->xfer[3].len = 2;
    req->xfer[3].cs_change = 1;

    req->xfer[4].tx_buf = &ts->cmd_crtl2;   /*REF OFF*/
    req->xfer[4].len = 2;
    req->xfer[4].cs_change = 1;

    req->xfer[5].tx_buf = &ts->cmd_crtl1;   /*DEFAULT*/
    req->xfer[5].len = 2;

    /* group all the transfers together, so we can't interfere with
     * reading touchscreen state; disable penirq while sampling
     */
    for (i = 0; i < 6; i++)
        spi_message_add_tail(&req->xfer[i], &req->msg);

    status = spi_sync(spi, &req->msg);
    sample = req->sample;

    kfree(req);

    return status ? : sample;
}

static int ad7877_process_data(struct ad7877 *ts)
{
    struct input_dev *input_dev = ts->input;
    unsigned Rt;
    u16 x, y, z1, z2;

    x = ts->conversion_data[AD7877_SEQ_XPOS] & MAX_12BIT;
    y = ts->conversion_data[AD7877_SEQ_YPOS] & MAX_12BIT;
    z1 = ts->conversion_data[AD7877_SEQ_Z1] & MAX_12BIT;
    z2 = ts->conversion_data[AD7877_SEQ_Z2] & MAX_12BIT;

    /*
     * The samples processed here are already preprocessed by the AD7877.
     * The preprocessing function consists of an averaging filter.
     * The combination of 'first conversion delay' and averaging provides a robust solution,
     * discarding the spurious noise in the signal and keeping only the data of interest.
     * The size of the averaging filter is programmable. (dev.platform_data, see linux/spi/ad7877.h)
     * Other user-programmable conversion controls include variable acquisition time,
     * and first conversion delay. Up to 16 averages can be taken per conversion.
     */

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

        /*
         * Sample found inconsistent, pressure is beyond
         * the maximum. Don't report it to user space.
         */
        if (Rt > ts->pressure_max)
            return -EINVAL;

        if (!timer_pending(&ts->timer))
            input_report_key(input_dev, BTN_TOUCH, 1);

        input_report_abs(input_dev, ABS_X, x);
        input_report_abs(input_dev, ABS_Y, y);
        input_report_abs(input_dev, ABS_PRESSURE, Rt);
        input_sync(input_dev);

        return 0;
    }

    return -EINVAL;
}

static inline void ad7877_ts_event_release(struct ad7877 *ts)
{
    struct input_dev *input_dev = ts->input;

    input_report_abs(input_dev, ABS_PRESSURE, 0);
    input_report_key(input_dev, BTN_TOUCH, 0);
    input_sync(input_dev);
}

static void ad7877_timer(unsigned long handle)
{
    struct ad7877 *ts = (void *)handle;
    unsigned long flags;

    spin_lock_irqsave(&ts->lock, flags);
    ad7877_ts_event_release(ts);
    spin_unlock_irqrestore(&ts->lock, flags);
}

static irqreturn_t ad7877_irq(int irq, void *handle)
{
    struct ad7877 *ts = handle;
    unsigned long flags;
    int error;

    error = spi_sync(ts->spi, &ts->msg);
    if (error) {
        dev_err(&ts->spi->dev, "spi_sync --> %d\n", error);
        goto out;
    }

    spin_lock_irqsave(&ts->lock, flags);
    error = ad7877_process_data(ts);
    if (!error)
        mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);
    spin_unlock_irqrestore(&ts->lock, flags);

out:
    return IRQ_HANDLED;
}

static void ad7877_disable(struct ad7877 *ts)
{
    mutex_lock(&ts->mutex);

    if (!ts->disabled) {
        ts->disabled = true;
        disable_irq(ts->spi->irq);

        if (del_timer_sync(&ts->timer))
            ad7877_ts_event_release(ts);
    }

    /*
     * We know the chip's in lowpower mode since we always
     * leave it that way after every request
     */

    mutex_unlock(&ts->mutex);
}

static void ad7877_enable(struct ad7877 *ts)
{
    mutex_lock(&ts->mutex);

    if (ts->disabled) {
        ts->disabled = false;
        enable_irq(ts->spi->irq);
    }

    mutex_unlock(&ts->mutex);
}

#define SHOW(name) static ssize_t \
name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
    struct ad7877 *ts = dev_get_drvdata(dev); \
    ssize_t v = ad7877_read_adc(ts->spi, \
            AD7877_READ_CHAN(name)); \
    if (v < 0) \
        return v; \
    return sprintf(buf, "%u\n", (unsigned) v); \
} \
static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);

SHOW(aux1)
SHOW(aux2)
SHOW(aux3)
SHOW(bat1)
SHOW(bat2)
SHOW(temp1)
SHOW(temp2)

static ssize_t ad7877_disable_show(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    return sprintf(buf, "%u\n", ts->disabled);
}

static ssize_t ad7877_disable_store(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    struct ad7877 *ts = dev_get_drvdata(dev);
    unsigned int val;
    int error;

    error = kstrtouint(buf, 10, &val);
    if (error)
        return error;

    if (val)
        ad7877_disable(ts);
    else
        ad7877_enable(ts);

    return count;
}

static DEVICE_ATTR(disable, 0664, ad7877_disable_show, ad7877_disable_store);

static ssize_t ad7877_dac_show(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    return sprintf(buf, "%u\n", ts->dac);
}

static ssize_t ad7877_dac_store(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    struct ad7877 *ts = dev_get_drvdata(dev);
    unsigned int val;
    int error;

    error = kstrtouint(buf, 10, &val);
    if (error)
        return error;

    mutex_lock(&ts->mutex);
    ts->dac = val & 0xFF;
    ad7877_write(ts->spi, AD7877_REG_DAC, (ts->dac << 4) | AD7877_DAC_CONF);
    mutex_unlock(&ts->mutex);

    return count;
}

static DEVICE_ATTR(dac, 0664, ad7877_dac_show, ad7877_dac_store);

static ssize_t ad7877_gpio3_show(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    return sprintf(buf, "%u\n", ts->gpio3);
}

static ssize_t ad7877_gpio3_store(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    struct ad7877 *ts = dev_get_drvdata(dev);
    unsigned int val;
    int error;

    error = kstrtouint(buf, 10, &val);
    if (error)
        return error;

    mutex_lock(&ts->mutex);
    ts->gpio3 = !!val;
    ad7877_write(ts->spi, AD7877_REG_EXTWRITE, AD7877_EXTW_GPIO_DATA |
         (ts->gpio4 << 4) | (ts->gpio3 << 5));
    mutex_unlock(&ts->mutex);

    return count;
}

static DEVICE_ATTR(gpio3, 0664, ad7877_gpio3_show, ad7877_gpio3_store);

static ssize_t ad7877_gpio4_show(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    return sprintf(buf, "%u\n", ts->gpio4);
}

static ssize_t ad7877_gpio4_store(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    struct ad7877 *ts = dev_get_drvdata(dev);
    unsigned int val;
    int error;

    error = kstrtouint(buf, 10, &val);
    if (error)
        return error;

    mutex_lock(&ts->mutex);
    ts->gpio4 = !!val;
    ad7877_write(ts->spi, AD7877_REG_EXTWRITE, AD7877_EXTW_GPIO_DATA |
             (ts->gpio4 << 4) | (ts->gpio3 << 5));
    mutex_unlock(&ts->mutex);

    return count;
}

static DEVICE_ATTR(gpio4, 0664, ad7877_gpio4_show, ad7877_gpio4_store);

static struct attribute *ad7877_attributes[] = {
    &dev_attr_temp1.attr,
    &dev_attr_temp2.attr,
    &dev_attr_aux1.attr,
    &dev_attr_aux2.attr,
    &dev_attr_aux3.attr,
    &dev_attr_bat1.attr,
    &dev_attr_bat2.attr,
    &dev_attr_disable.attr,
    &dev_attr_dac.attr,
    &dev_attr_gpio3.attr,
    &dev_attr_gpio4.attr,
    NULL
};

static umode_t ad7877_attr_is_visible(struct kobject *kobj,
                     struct attribute *attr, int n)
{
    umode_t mode = attr->mode;

    if (attr == &dev_attr_aux3.attr) {
        if (gpio3)
            mode = 0;
    } else if (attr == &dev_attr_gpio3.attr) {
        if (!gpio3)
            mode = 0;
    }

    return mode;
}

static const struct attribute_group ad7877_attr_group = {
    .is_visible = ad7877_attr_is_visible,
    .attrs      = ad7877_attributes,
};

static void ad7877_setup_ts_def_msg(struct spi_device *spi, struct ad7877 *ts)
{
    struct spi_message *m;
    int i;

    ts->cmd_crtl2 = AD7877_WRITEADD(AD7877_REG_CTRL2) |
            AD7877_POL(ts->stopacq_polarity) |
            AD7877_AVG(ts->averaging) | AD7877_PM(1) |
            AD7877_TMR(ts->pen_down_acc_interval) |
            AD7877_ACQ(ts->acquisition_time) |
            AD7877_FCD(ts->first_conversion_delay);

    ad7877_write(spi, AD7877_REG_CTRL2, ts->cmd_crtl2);

    ts->cmd_crtl1 = AD7877_WRITEADD(AD7877_REG_CTRL1) |
            AD7877_READADD(AD7877_REG_XPLUS-1) |
            AD7877_MODE_SEQ1 | AD7877_DFR;

    ad7877_write(spi, AD7877_REG_CTRL1, ts->cmd_crtl1);

    ts->cmd_dummy = 0;

    m = &ts->msg;

    spi_message_init(m);

    m->context = ts;

    ts->xfer[0].tx_buf = &ts->cmd_crtl1;
    ts->xfer[0].len = 2;
    ts->xfer[0].cs_change = 1;

    spi_message_add_tail(&ts->xfer[0], m);

    ts->xfer[1].tx_buf = &ts->cmd_dummy; /* Send ZERO */
    ts->xfer[1].len = 2;
    ts->xfer[1].cs_change = 1;

    spi_message_add_tail(&ts->xfer[1], m);

    for (i = 0; i < AD7877_NR_SENSE; i++) {
        ts->xfer[i + 2].rx_buf = &ts->conversion_data[AD7877_SEQ_YPOS + i];
        ts->xfer[i + 2].len = 2;
        if (i < (AD7877_NR_SENSE - 1))
            ts->xfer[i + 2].cs_change = 1;
        spi_message_add_tail(&ts->xfer[i + 2], m);
    }
}

static int __devinit ad7877_probe(struct spi_device *spi)
{
    struct ad7877           *ts;
    struct input_dev        *input_dev;
    struct ad7877_platform_data *pdata = spi->dev.platform_data;
    int             err;
    u16             verify;

    if (!spi->irq) {
        dev_dbg(&spi->dev, "no IRQ?\n");
        return -ENODEV;
    }

    if (!pdata) {
        dev_dbg(&spi->dev, "no platform data?\n");
        return -ENODEV;
    }

    /* don't exceed max specified SPI CLK frequency */
    if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
        dev_dbg(&spi->dev, "SPI CLK %d Hz?\n",spi->max_speed_hz);
        return -EINVAL;
    }

    spi->bits_per_word = 16;
    err = spi_setup(spi);
    if (err) {
        dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
        return err;
    }

    ts = kzalloc(sizeof(struct ad7877), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!ts || !input_dev) {
        err = -ENOMEM;
        goto err_free_mem;
    }

    dev_set_drvdata(&spi->dev, ts);
    ts->spi = spi;
    ts->input = input_dev;

    setup_timer(&ts->timer, ad7877_timer, (unsigned long) ts);
    mutex_init(&ts->mutex);
    spin_lock_init(&ts->lock);

    ts->model = pdata->model ? : 7877;
    ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
    ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
    ts->pressure_max = pdata->pressure_max ? : ~0;

    ts->stopacq_polarity = pdata->stopacq_polarity;
    ts->first_conversion_delay = pdata->first_conversion_delay;
    ts->acquisition_time = pdata->acquisition_time;
    ts->averaging = pdata->averaging;
    ts->pen_down_acc_interval = pdata->pen_down_acc_interval;

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

    input_dev->name = "AD7877 Touchscreen";
    input_dev->phys = ts->phys;
    input_dev->dev.parent = &spi->dev;

    __set_bit(EV_KEY, input_dev->evbit);
    __set_bit(BTN_TOUCH, input_dev->keybit);
    __set_bit(EV_ABS, input_dev->evbit);
    __set_bit(ABS_X, input_dev->absbit);
    __set_bit(ABS_Y, input_dev->absbit);
    __set_bit(ABS_PRESSURE, input_dev->absbit);

    input_set_abs_params(input_dev, ABS_X,
            pdata->x_min ? : 0,
            pdata->x_max ? : MAX_12BIT,
            0, 0);
    input_set_abs_params(input_dev, ABS_Y,
            pdata->y_min ? : 0,
            pdata->y_max ? : MAX_12BIT,
            0, 0);
    input_set_abs_params(input_dev, ABS_PRESSURE,
            pdata->pressure_min, pdata->pressure_max, 0, 0);

    ad7877_write(spi, AD7877_REG_SEQ1, AD7877_MM_SEQUENCE);

    verify = ad7877_read(spi, AD7877_REG_SEQ1);

    if (verify != AD7877_MM_SEQUENCE){
        dev_err(&spi->dev, "%s: Failed to probe %s\n",
            dev_name(&spi->dev), input_dev->name);
        err = -ENODEV;
        goto err_free_mem;
    }

    if (gpio3)
        ad7877_write(spi, AD7877_REG_EXTWRITE, AD7877_EXTW_GPIO_3_CONF);

    ad7877_setup_ts_def_msg(spi, ts);

    /* Request AD7877 /DAV GPIO interrupt */

    err = request_threaded_irq(spi->irq, NULL, ad7877_irq,
                   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                   spi->dev.driver->name, ts);
    if (err) {
        dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
        goto err_free_mem;
    }

    err = sysfs_create_group(&spi->dev.kobj, &ad7877_attr_group);
    if (err)
        goto err_free_irq;

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

    return 0;

err_remove_attr_group:
    sysfs_remove_group(&spi->dev.kobj, &ad7877_attr_group);
err_free_irq:
    free_irq(spi->irq, ts);
err_free_mem:
    input_free_device(input_dev);
    kfree(ts);
    dev_set_drvdata(&spi->dev, NULL);
    return err;
}

static int __devexit ad7877_remove(struct spi_device *spi)
{
    struct ad7877 *ts = dev_get_drvdata(&spi->dev);

    sysfs_remove_group(&spi->dev.kobj, &ad7877_attr_group);

    ad7877_disable(ts);
    free_irq(ts->spi->irq, ts);

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

    dev_dbg(&spi->dev, "unregistered touchscreen\n");
    dev_set_drvdata(&spi->dev, NULL);

    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int ad7877_suspend(struct device *dev)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    ad7877_disable(ts);

    return 0;
}

static int ad7877_resume(struct device *dev)
{
    struct ad7877 *ts = dev_get_drvdata(dev);

    ad7877_enable(ts);

    return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(ad7877_pm, ad7877_suspend, ad7877_resume);

static struct spi_driver ad7877_driver = {
    .driver = {
        .name   = "ad7877",
        .owner  = THIS_MODULE,
        .pm = &ad7877_pm,
    },
    .probe      = ad7877_probe,
    .remove     = __devexit_p(ad7877_remove),
};

module_spi_driver(ad7877_driver);

MODULE_AUTHOR("Michael Hennerich <[email protected]>");
MODULE_DESCRIPTION("AD7877 touchscreen Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:ad7877");