Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6

[mirror_ubuntu-artful-kernel.git] / drivers / input / touchscreen / ads7846.c

/*
 * ADS7846 based touchscreen and sensor driver
 *
 * 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
 *
 *  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/device.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/spi/ads7846.h>
#include <asm/irq.h>

#ifdef  CONFIG_ARM
#include <asm/mach-types.h>
#ifdef  CONFIG_ARCH_OMAP
#include <asm/arch/gpio.h>
#endif
#endif


/*
 * This code has been heavily tested on a Nokia 770, and lightly
 * tested on other ads7846 devices (OSK/Mistral, Lubbock).
 * Support for ads7843 and ads7845 has only been stubbed in.
 *
 * IRQ handling needs a workaround because of a shortcoming in handling
 * edge triggered IRQs on some platforms like the OMAP1/2. These
 * platforms don't handle the ARM lazy IRQ disabling properly, thus we
 * have to maintain our own SW IRQ disabled status. This should be
 * removed as soon as the affected platform's IRQ handling is fixed.
 *
 * app note sbaa036 talks in more detail about accurate sampling...
 * that ought to help in situations like LCDs inducing noise (which
 * can also be helped by using synch signals) and more generally.
 * This driver tries to utilize the measures described in the app
 * note. The strength of filtering can be set in the board-* specific
 * files.
 */

#define TS_POLL_PERIOD  msecs_to_jiffies(10)

/* this driver doesn't aim at the peak continuous sample rate */
#define SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)

struct ts_event {
        /* For portability, we can't read 12 bit values using SPI (which
         * would make the controller deliver them as native byteorder u16
         * with msbs zeroed).  Instead, we read them as two 8-bit values,
         * which need byteswapping then range adjustment.
         */
        __be16 x;
        __be16 y;
        __be16 z1, z2;
        int    ignore;
};

struct ads7846 {
        struct input_dev        *input;
        char                    phys[32];

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

        u8                      read_x, read_y, read_z1, read_z2, pwrdown;
        u16                     dummy;          /* for the pwrdown read */
        struct ts_event         tc;

        struct spi_transfer     xfer[10];
        struct spi_message      msg[5];
        struct spi_message      *last_msg;
        int                     msg_idx;
        int                     read_cnt;
        int                     read_rep;
        int                     last_read;

        u16                     debounce_max;
        u16                     debounce_tol;
        u16                     debounce_rep;

        spinlock_t              lock;
        struct timer_list       timer;          /* P: lock */
        unsigned                pendown:1;      /* P: lock */
        unsigned                pending:1;      /* P: lock */
// FIXME remove "irq_disabled"
        unsigned                irq_disabled:1; /* P: lock */
        unsigned                disabled:1;

        int                     (*get_pendown_state)(void);
};

/* leave chip selected when we're done, for quicker re-select? */
#if     0
#define CS_CHANGE(xfer) ((xfer).cs_change = 1)
#else
#define CS_CHANGE(xfer) ((xfer).cs_change = 0)
#endif

/*--------------------------------------------------------------------------*/

/* The ADS7846 has touchscreen and other sensors.
 * Earlier ads784x chips are somewhat compatible.
 */
#define ADS_START               (1 << 7)
#define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
#define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
#define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
#define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
#define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
#define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
#define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
#define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
#define ADS_8_BIT               (1 << 3)
#define ADS_12_BIT              (0 << 3)
#define ADS_SER                 (1 << 2)        /* non-differential */
#define ADS_DFR                 (0 << 2)        /* differential */
#define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
#define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
#define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
#define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */

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

/* leave ADC powered up (disables penirq) between differential samples */
#define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
        | ADS_12_BIT | ADS_DFR)

#define READ_Y  (READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)
#define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
#define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)

#define READ_X  (READ_12BIT_DFR(x)  | ADS_PD10_ADC_ON)
#define PWRDOWN (READ_12BIT_DFR(y)  | ADS_PD10_PDOWN)   /* LAST */

/* single-ended samples need to first power up reference voltage;
 * we leave both ADC and VREF powered
 */
#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
        | ADS_12_BIT | ADS_SER)

#define REF_ON  (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
#define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)

/*--------------------------------------------------------------------------*/

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

struct ser_req {
        u8                      ref_on;
        u8                      command;
        u8                      ref_off;
        u16                     scratch;
        __be16                  sample;
        struct spi_message      msg;
        struct spi_transfer     xfer[6];
};

static void ads7846_enable(struct ads7846 *ts);
static void ads7846_disable(struct ads7846 *ts);

static int device_suspended(struct device *dev)
{
        struct ads7846 *ts = dev_get_drvdata(dev);
        return dev->power.power_state.event != PM_EVENT_ON || ts->disabled;
}

static int ads7846_read12_ser(struct device *dev, unsigned command)
{
        struct spi_device       *spi = to_spi_device(dev);
        struct ads7846          *ts = dev_get_drvdata(dev);
        struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
        int                     status;
        int                     sample;
        int                     i;

        if (!req)
                return -ENOMEM;

        spi_message_init(&req->msg);

        /* activate reference, so it has time to settle; */
        req->ref_on = REF_ON;
        req->xfer[0].tx_buf = &req->ref_on;
        req->xfer[0].len = 1;
        req->xfer[1].rx_buf = &req->scratch;
        req->xfer[1].len = 2;

        /*
         * for external VREF, 0 usec (and assume it's always on);
         * for 1uF, use 800 usec;
         * no cap, 100 usec.
         */
        req->xfer[1].delay_usecs = ts->vref_delay_usecs;

        /* take sample */
        req->command = (u8) command;
        req->xfer[2].tx_buf = &req->command;
        req->xfer[2].len = 1;
        req->xfer[3].rx_buf = &req->sample;
        req->xfer[3].len = 2;

        /* REVISIT:  take a few more samples, and compare ... */

        /* turn off reference */
        req->ref_off = REF_OFF;
        req->xfer[4].tx_buf = &req->ref_off;
        req->xfer[4].len = 1;
        req->xfer[5].rx_buf = &req->scratch;
        req->xfer[5].len = 2;

        CS_CHANGE(req->xfer[5]);

        /* 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);

        ts->irq_disabled = 1;
        disable_irq(spi->irq);
        status = spi_sync(spi, &req->msg);
        ts->irq_disabled = 0;
        enable_irq(spi->irq);

        if (req->msg.status)
                status = req->msg.status;

        /* on-wire is a must-ignore bit, a BE12 value, then padding */
        sample = be16_to_cpu(req->sample);
        sample = sample >> 3;
        sample &= 0x0fff;

        kfree(req);
        return status ? status : sample;
}

#define SHOW(name) static ssize_t \
name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
        ssize_t v = ads7846_read12_ser(dev, \
                        READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
        if (v < 0) \
                return v; \
        return sprintf(buf, "%u\n", (unsigned) v); \
} \
static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);

SHOW(temp0)
SHOW(temp1)
SHOW(vaux)
SHOW(vbatt)

static int is_pen_down(struct device *dev)
{
        struct ads7846          *ts = dev_get_drvdata(dev);

        return ts->pendown;
}

static ssize_t ads7846_pen_down_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%u\n", is_pen_down(dev));
}

static DEVICE_ATTR(pen_down, S_IRUGO, ads7846_pen_down_show, NULL);

static ssize_t ads7846_disable_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct ads7846  *ts = dev_get_drvdata(dev);

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

static ssize_t ads7846_disable_store(struct device *dev,
                                     struct device_attribute *attr,
                                     const char *buf, size_t count)
{
        struct ads7846 *ts = dev_get_drvdata(dev);
        char *endp;
        int i;

        i = simple_strtoul(buf, &endp, 10);
        spin_lock_irq(&ts->lock);

        if (i)
                ads7846_disable(ts);
        else
                ads7846_enable(ts);

        spin_unlock_irq(&ts->lock);

        return count;
}

static DEVICE_ATTR(disable, 0664, ads7846_disable_show, ads7846_disable_store);

/*--------------------------------------------------------------------------*/

/*
 * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
 * to retrieve touchscreen status.
 *
 * The SPI transfer completion callback does the real work.  It reports
 * touchscreen events and reactivates the timer (or IRQ) as appropriate.
 */

static void ads7846_rx(void *ads)
{
        struct ads7846          *ts = ads;
        struct input_dev        *input_dev = ts->input;
        unsigned                Rt;
        unsigned                sync = 0;
        u16                     x, y, z1, z2;
        unsigned long           flags;

        /* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
         * built from two 8 bit values written msb-first.
         */
        x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
        y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
        z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
        z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;

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

        if (likely(x && z1 && !device_suspended(&ts->spi->dev))) {
                /* compute touch pressure resistance using equation #2 */
                Rt = z2;
                Rt -= z1;
                Rt *= x;
                Rt *= ts->x_plate_ohms;
                Rt /= z1;
                Rt = (Rt + 2047) >> 12;
        } else
                Rt = 0;

        /* 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 */
        if (ts->tc.ignore || Rt > ts->pressure_max) {
                mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
                return;
        }

        /* NOTE:  "pendown" is inferred from pressure; we don't rely on
         * being able to check nPENIRQ status, or "friendly" trigger modes
         * (both-edges is much better than just-falling or low-level).
         *
         * REVISIT:  some boards may require reading nPENIRQ; it's
         * needed on 7843.  and 7845 reads pressure differently...
         *
         * REVISIT:  the touchscreen might not be connected; this code
         * won't notice that, even if nPENIRQ never fires ...
         */
        if (!ts->pendown && Rt != 0) {
                input_report_key(input_dev, BTN_TOUCH, 1);
                sync = 1;
        } else if (ts->pendown && Rt == 0) {
                input_report_key(input_dev, BTN_TOUCH, 0);
                sync = 1;
        }

        if (Rt) {
                input_report_abs(input_dev, ABS_X, x);
                input_report_abs(input_dev, ABS_Y, y);
                sync = 1;
        }

        if (sync) {
                input_report_abs(input_dev, ABS_PRESSURE, Rt);
                input_sync(input_dev);
        }

#ifdef  VERBOSE
        if (Rt || ts->pendown)
                pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
                        x, y, Rt, Rt ? "" : " UP");
#endif

        spin_lock_irqsave(&ts->lock, flags);

        ts->pendown = (Rt != 0);
        mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);

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

static void ads7846_debounce(void *ads)
{
        struct ads7846          *ts = ads;
        struct spi_message      *m;
        struct spi_transfer     *t;
        int                     val;
        int                     status;

        m = &ts->msg[ts->msg_idx];
        t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
        val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
        if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
                /* Repeat it, if this was the first read or the read
                 * wasn't consistent enough. */
                if (ts->read_cnt < ts->debounce_max) {
                        ts->last_read = val;
                        ts->read_cnt++;
                } else {
                        /* Maximum number of debouncing reached and still
                         * not enough number of consistent readings. Abort
                         * the whole sample, repeat it in the next sampling
                         * period.
                         */
                        ts->tc.ignore = 1;
                        ts->read_cnt = 0;
                        /* Last message will contain ads7846_rx() as the
                         * completion function.
                         */
                        m = ts->last_msg;
                }
                /* Start over collecting consistent readings. */
                ts->read_rep = 0;
        } else {
                if (++ts->read_rep > ts->debounce_rep) {
                        /* Got a good reading for this coordinate,
                         * go for the next one. */
                        ts->tc.ignore = 0;
                        ts->msg_idx++;
                        ts->read_cnt = 0;
                        ts->read_rep = 0;
                        m++;
                } else
                        /* Read more values that are consistent. */
                        ts->read_cnt++;
        }
        status = spi_async(ts->spi, m);
        if (status)
                dev_err(&ts->spi->dev, "spi_async --> %d\n",
                                status);
}

static void ads7846_timer(unsigned long handle)
{
        struct ads7846  *ts = (void *)handle;
        int             status = 0;

        spin_lock_irq(&ts->lock);

        if (unlikely(ts->msg_idx && !ts->pendown)) {
                /* measurement cycle ended */
                if (!device_suspended(&ts->spi->dev)) {
                        ts->irq_disabled = 0;
                        enable_irq(ts->spi->irq);
                }
                ts->pending = 0;
                ts->msg_idx = 0;
        } else {
                /* pen is still down, continue with the measurement */
                ts->msg_idx = 0;
                status = spi_async(ts->spi, &ts->msg[0]);
                if (status)
                        dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
        }

        spin_unlock_irq(&ts->lock);
}

static irqreturn_t ads7846_irq(int irq, void *handle)
{
        struct ads7846 *ts = handle;
        unsigned long flags;

        spin_lock_irqsave(&ts->lock, flags);
        if (likely(ts->get_pendown_state())) {
                if (!ts->irq_disabled) {
                        /* The ARM do_simple_IRQ() dispatcher doesn't act
                         * like the other dispatchers:  it will report IRQs
                         * even after they've been disabled.  We work around
                         * that here.  (The "generic irq" framework may help...)
                         */
                        ts->irq_disabled = 1;
                        disable_irq(ts->spi->irq);
                        ts->pending = 1;
                        mod_timer(&ts->timer, jiffies);
                }
        }
        spin_unlock_irqrestore(&ts->lock, flags);

        return IRQ_HANDLED;
}

/*--------------------------------------------------------------------------*/

/* Must be called with ts->lock held */
static void ads7846_disable(struct ads7846 *ts)
{
        if (ts->disabled)
                return;

        ts->disabled = 1;

        /* are we waiting for IRQ, or polling? */
        if (!ts->pending) {
                ts->irq_disabled = 1;
                disable_irq(ts->spi->irq);
        } else {
                /* the timer will run at least once more, and
                 * leave everything in a clean state, IRQ disabled
                 */
                while (ts->pending) {
                        spin_unlock_irq(&ts->lock);
                        msleep(1);
                        spin_lock_irq(&ts->lock);
                }
        }

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

}

/* Must be called with ts->lock held */
static void ads7846_enable(struct ads7846 *ts)
{
        if (!ts->disabled)
                return;

        ts->disabled = 0;
        ts->irq_disabled = 0;
        enable_irq(ts->spi->irq);
}

static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
{
        struct ads7846 *ts = dev_get_drvdata(&spi->dev);

        spin_lock_irq(&ts->lock);

        spi->dev.power.power_state = message;
        ads7846_disable(ts);

        spin_unlock_irq(&ts->lock);

        return 0;

}

static int ads7846_resume(struct spi_device *spi)
{
        struct ads7846 *ts = dev_get_drvdata(&spi->dev);

        spin_lock_irq(&ts->lock);

        spi->dev.power.power_state = PMSG_ON;
        ads7846_enable(ts);

        spin_unlock_irq(&ts->lock);

        return 0;
}

static int __devinit ads7846_probe(struct spi_device *spi)
{
        struct ads7846                  *ts;
        struct input_dev                *input_dev;
        struct ads7846_platform_data    *pdata = spi->dev.platform_data;
        struct spi_message              *m;
        struct spi_transfer             *x;
        int                             err;

        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 sample rate */
        if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
                dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
                                (spi->max_speed_hz/SAMPLE_BITS)/1000);
                return -EINVAL;
        }

        /* REVISIT when the irq can be triggered active-low, or if for some
         * reason the touchscreen isn't hooked up, we don't need to access
         * the pendown state.
         */
        if (pdata->get_pendown_state == NULL) {
                dev_dbg(&spi->dev, "no get_pendown_state function?\n");
                return -EINVAL;
        }

        /* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
         * that even if the hardware can do that, the SPI controller driver
         * may not.  So we stick to very-portable 8 bit words, both RX and TX.
         */
        spi->bits_per_word = 8;

        ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
        input_dev = input_allocate_device();
        if (!ts || !input_dev) {
                err = -ENOMEM;
                goto err_free_mem;
        }

        dev_set_drvdata(&spi->dev, ts);
        spi->dev.power.power_state = PMSG_ON;

        ts->spi = spi;
        ts->input = input_dev;

        init_timer(&ts->timer);
        ts->timer.data = (unsigned long) ts;
        ts->timer.function = ads7846_timer;

        spin_lock_init(&ts->lock);

        ts->model = pdata->model ? : 7846;
        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;
        if (pdata->debounce_max) {
                ts->debounce_max = pdata->debounce_max;
                ts->debounce_tol = pdata->debounce_tol;
                ts->debounce_rep = pdata->debounce_rep;
                if (ts->debounce_rep > ts->debounce_max + 1)
                        ts->debounce_rep = ts->debounce_max - 1;
        } else
                ts->debounce_tol = ~0;
        ts->get_pendown_state = pdata->get_pendown_state;

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

        input_dev->name = "ADS784x Touchscreen";
        input_dev->phys = ts->phys;
        input_dev->cdev.dev = &spi->dev;

        input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
        input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
        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);

        /* set up the transfers to read touchscreen state; this assumes we
         * use formula #2 for pressure, not #3.
         */
        m = &ts->msg[0];
        x = ts->xfer;

        spi_message_init(m);

        /* y- still on; turn on only y+ (and ADC) */
        ts->read_y = READ_Y;
        x->tx_buf = &ts->read_y;
        x->len = 1;
        spi_message_add_tail(x, m);

        x++;
        x->rx_buf = &ts->tc.y;
        x->len = 2;
        spi_message_add_tail(x, m);

        m->complete = ads7846_debounce;
        m->context = ts;

        m++;
        spi_message_init(m);

        /* turn y- off, x+ on, then leave in lowpower */
        x++;
        ts->read_x = READ_X;
        x->tx_buf = &ts->read_x;
        x->len = 1;
        spi_message_add_tail(x, m);

        x++;
        x->rx_buf = &ts->tc.x;
        x->len = 2;
        spi_message_add_tail(x, m);

        m->complete = ads7846_debounce;
        m->context = ts;

        /* turn y+ off, x- on; we'll use formula #2 */
        if (ts->model == 7846) {
                m++;
                spi_message_init(m);

                x++;
                ts->read_z1 = READ_Z1;
                x->tx_buf = &ts->read_z1;
                x->len = 1;
                spi_message_add_tail(x, m);

                x++;
                x->rx_buf = &ts->tc.z1;
                x->len = 2;
                spi_message_add_tail(x, m);

                m->complete = ads7846_debounce;
                m->context = ts;

                m++;
                spi_message_init(m);

                x++;
                ts->read_z2 = READ_Z2;
                x->tx_buf = &ts->read_z2;
                x->len = 1;
                spi_message_add_tail(x, m);

                x++;
                x->rx_buf = &ts->tc.z2;
                x->len = 2;
                spi_message_add_tail(x, m);

                m->complete = ads7846_debounce;
                m->context = ts;
        }

        /* power down */
        m++;
        spi_message_init(m);

        x++;
        ts->pwrdown = PWRDOWN;
        x->tx_buf = &ts->pwrdown;
        x->len = 1;
        spi_message_add_tail(x, m);

        x++;
        x->rx_buf = &ts->dummy;
        x->len = 2;
        CS_CHANGE(*x);
        spi_message_add_tail(x, m);

        m->complete = ads7846_rx;
        m->context = ts;

        ts->last_msg = m;

        if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
                        spi->dev.driver->name, ts)) {
                dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
                err = -EBUSY;
                goto err_free_mem;
        }

        dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);

        /* take a first sample, leaving nPENIRQ active; avoid
         * the touchscreen, in case it's not connected.
         */
        (void) ads7846_read12_ser(&spi->dev,
                          READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);

        /* ads7843/7845 don't have temperature sensors, and
         * use the other sensors a bit differently too
         */
        if (ts->model == 7846) {
                device_create_file(&spi->dev, &dev_attr_temp0);
                device_create_file(&spi->dev, &dev_attr_temp1);
        }
        if (ts->model != 7845)
                device_create_file(&spi->dev, &dev_attr_vbatt);
        device_create_file(&spi->dev, &dev_attr_vaux);

        device_create_file(&spi->dev, &dev_attr_pen_down);

        device_create_file(&spi->dev, &dev_attr_disable);

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

        return 0;

 err_remove_attr:
        device_remove_file(&spi->dev, &dev_attr_disable);
        device_remove_file(&spi->dev, &dev_attr_pen_down);
        if (ts->model == 7846) {
                device_remove_file(&spi->dev, &dev_attr_temp1);
                device_remove_file(&spi->dev, &dev_attr_temp0);
        }
        if (ts->model != 7845)
                device_remove_file(&spi->dev, &dev_attr_vbatt);
        device_remove_file(&spi->dev, &dev_attr_vaux);

        free_irq(spi->irq, ts);
 err_free_mem:
        input_free_device(input_dev);
        kfree(ts);
        return err;
}

static int __devexit ads7846_remove(struct spi_device *spi)
{
        struct ads7846          *ts = dev_get_drvdata(&spi->dev);

        input_unregister_device(ts->input);

        ads7846_suspend(spi, PMSG_SUSPEND);

        device_remove_file(&spi->dev, &dev_attr_disable);
        device_remove_file(&spi->dev, &dev_attr_pen_down);
        if (ts->model == 7846) {
                device_remove_file(&spi->dev, &dev_attr_temp1);
                device_remove_file(&spi->dev, &dev_attr_temp0);
        }
        if (ts->model != 7845)
                device_remove_file(&spi->dev, &dev_attr_vbatt);
        device_remove_file(&spi->dev, &dev_attr_vaux);

        free_irq(ts->spi->irq, ts);
        /* suspend left the IRQ disabled */
        enable_irq(ts->spi->irq);

        kfree(ts);

        dev_dbg(&spi->dev, "unregistered touchscreen\n");
        return 0;
}

static struct spi_driver ads7846_driver = {
        .driver = {
                .name   = "ads7846",
                .bus    = &spi_bus_type,
                .owner  = THIS_MODULE,
        },
        .probe          = ads7846_probe,
        .remove         = __devexit_p(ads7846_remove),
        .suspend        = ads7846_suspend,
        .resume         = ads7846_resume,
};

static int __init ads7846_init(void)
{
        /* grr, board-specific init should stay out of drivers!! */

#ifdef  CONFIG_ARCH_OMAP
        if (machine_is_omap_osk()) {
                /* GPIO4 = PENIRQ; GPIO6 = BUSY */
                omap_request_gpio(4);
                omap_set_gpio_direction(4, 1);
                omap_request_gpio(6);
                omap_set_gpio_direction(6, 1);
        }
        // also TI 1510 Innovator, bitbanging through FPGA
        // also Nokia 770
        // also Palm Tungsten T2
#endif

        // PXA:
        // also Dell Axim X50
        // also HP iPaq H191x/H192x/H415x/H435x
        // also Intel Lubbock (additional to UCB1400; as temperature sensor)
        // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)

        // Atmel at91sam9261-EK uses ads7843

        // also various AMD Au1x00 devel boards

        return spi_register_driver(&ads7846_driver);
}
module_init(ads7846_init);

static void __exit ads7846_exit(void)
{
        spi_unregister_driver(&ads7846_driver);

#ifdef  CONFIG_ARCH_OMAP
        if (machine_is_omap_osk()) {
                omap_free_gpio(4);
                omap_free_gpio(6);
        }
#endif

}
module_exit(ads7846_exit);

MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
MODULE_LICENSE("GPL");