/*
 * 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 <imre.deak@nokia.com>
 *
 * 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/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");

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 = spi_get_drvdata(spi);
        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 ad7877_probe(struct spi_device *spi)
{
        struct ad7877                   *ts;
        struct input_dev                *input_dev;
        struct ad7877_platform_data     *pdata = dev_get_platdata(&spi->dev);
        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;
        }

        spi_set_drvdata(spi, 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);
        return err;
}

static int ad7877_remove(struct spi_device *spi)
{
        struct ad7877 *ts = spi_get_drvdata(spi);

        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");

        return 0;
}

static int __maybe_unused ad7877_suspend(struct device *dev)
{
        struct ad7877 *ts = dev_get_drvdata(dev);

        ad7877_disable(ts);

        return 0;
}

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

        ad7877_enable(ts);

        return 0;
}

static SIMPLE_DEV_PM_OPS(ad7877_pm, ad7877_suspend, ad7877_resume);

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

module_spi_driver(ad7877_driver);

MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("AD7877 touchscreen Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:ad7877");