Input: add AD7877 touchscreen driver

[dtor@mail.ru: locking and other fixups]
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

3 files changed, 858 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index a31d43494a8d..afeb7554bfe2 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -29,6 +29,19 @@ config TOUCHSCREEN_ADS7846
           To compile this driver as a module, choose M here: the
           module will be called ads7846.
 
+config TOUCHSCREEN_AD7877
+        tristate "AD7877 based touchscreens"
+        depends on SPI_MASTER
+        help
+          Say Y here if you have a touchscreen interface using the
+          AD7877 controller, and your board-specific initialization
+          code includes that in its table of SPI devices.
+
+          If unsure, say N (but it's safe to say "Y").
+
+          To compile this driver as a module, choose M here: the
+          module will be called ad7877.
+
 config TOUCHSCREEN_BITSY
         tristate "Compaq iPAQ H3600 (Bitsy) touchscreen"
         depends on SA1100_BITSY
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 82dd918a4dec..45dfcd61be11 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -6,6 +6,7 @@
 
 wm97xx-ts-y := wm97xx-core.o
 
+obj-$(CONFIG_TOUCHSCREEN_AD7877)        += ad7877.o
 obj-$(CONFIG_TOUCHSCREEN_ADS7846)       += ads7846.o
 obj-$(CONFIG_TOUCHSCREEN_ATMEL_TSADCC)  += atmel_tsadcc.o
 obj-$(CONFIG_TOUCHSCREEN_BITSY)         += h3600_ts_input.o
diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
new file mode 100644
index 000000000000..e4728a28f492
--- /dev/null
+++ b/drivers/input/touchscreen/ad7877.c
@@ -0,0 +1,844 @@
+/*
+ * 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/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/ad7877.h>
+#include <asm/irq.h>
+
+#define TS_PEN_UP_TIMEOUT       msecs_to_jiffies(50)
+
+#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;
+        u16                     sample;
+        struct spi_message      msg;
+        struct spi_transfer     xfer[6];
+};
+
+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;
+
+        u16                     conversion_data[AD7877_NR_SENSE];
+
+        struct spi_transfer     xfer[AD7877_NR_SENSE + 2];
+        struct spi_message      msg;
+
+        struct mutex            mutex;
+        unsigned                disabled:1;     /* P: mutex */
+        unsigned                gpio3:1;        /* P: mutex */
+        unsigned                gpio4:1;        /* P: mutex */
+
+        spinlock_t              lock;
+        struct timer_list       timer;          /* P: lock */
+        unsigned                pending:1;      /* P: lock */
+};
+
+static int gpio3;
+module_param(gpio3, int, 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[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[1].tx_buf = &req->ref_on;
+        req->xfer[1].len = 2;
+        req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+
+        req->xfer[2].tx_buf = &req->command;
+        req->xfer[2].len = 2;
+        req->xfer[2].delay_usecs = ts->vref_delay_usecs;
+
+        req->xfer[3].rx_buf = &req->sample;
+        req->xfer[3].len = 2;
+
+        req->xfer[4].tx_buf = &ts->cmd_crtl2;   /*REF OFF*/
+        req->xfer[4].len = 2;
+
+        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 void ad7877_rx(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;
+
+                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);
+        }
+}
+
+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_sync(input_dev);
+}
+
+static void ad7877_timer(unsigned long handle)
+{
+        struct ad7877 *ts = (void *)handle;
+
+        ad7877_ts_event_release(ts);
+}
+
+static irqreturn_t ad7877_irq(int irq, void *handle)
+{
+        struct ad7877 *ts = handle;
+        unsigned long flags;
+        int status;
+
+        /*
+         * The repeated conversion sequencer controlled by TMR kicked off
+         * too fast. We ignore the last and process the sample sequence
+         * currently in the queue. It can't be older than 9.4ms, and we
+         * need to avoid that ts->msg doesn't get issued twice while in work.
+         */
+
+        spin_lock_irqsave(&ts->lock, flags);
+        if (!ts->pending) {
+                ts->pending = 1;
+
+                status = spi_async(ts->spi, &ts->msg);
+                if (status)
+                        dev_err(&ts->spi->dev, "spi_sync --> %d\n", status);
+        }
+        spin_unlock_irqrestore(&ts->lock, flags);
+
+        return IRQ_HANDLED;
+}
+
+static void ad7877_callback(void *_ts)
+{
+        struct ad7877 *ts = _ts;
+
+        spin_lock_irq(&ts->lock);
+
+        ad7877_rx(ts);
+        ts->pending = 0;
+        mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);
+
+        spin_unlock_irq(&ts->lock);
+}
+
+static void ad7877_disable(struct ad7877 *ts)
+{
+        mutex_lock(&ts->mutex);
+
+        if (!ts->disabled) {
+                ts->disabled = 1;
+                disable_irq(ts->spi->irq);
+
+                /* Wait for spi_async callback */
+                while (ts->pending)
+                        msleep(1);
+
+                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 = 0;
+                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 long val;
+        int error;
+
+        error = strict_strtoul(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 long val;
+        int error;
+
+        error = strict_strtoul(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 long val;
+        int error;
+
+        error = strict_strtoul(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 long val;
+        int error;
+
+        error = strict_strtoul(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_bat1.attr,
+        &dev_attr_bat2.attr,
+        &dev_attr_disable.attr,
+        &dev_attr_dac.attr,
+        &dev_attr_gpio4.attr,
+        NULL
+};
+
+static const struct attribute_group ad7877_attr_group = {
+        .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->complete = ad7877_callback;
+        m->context = ts;
+
+        ts->xfer[0].tx_buf = &ts->cmd_crtl1;
+        ts->xfer[0].len = 2;
+
+        spi_message_add_tail(&ts->xfer[0], m);
+
+        ts->xfer[1].tx_buf = &ts->cmd_dummy; /* Send ZERO */
+        ts->xfer[1].len = 2;
+
+        spi_message_add_tail(&ts->xfer[1], m);
+
+        for (i = 0; i < 11; i++) {
+                ts->xfer[i + 2].rx_buf = &ts->conversion_data[AD7877_SEQ_YPOS + i];
+                ts->xfer[i + 2].len = 2;
+                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;
+        }
+
+        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_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_irq(spi->irq, ad7877_irq, IRQF_TRIGGER_FALLING |
+                        IRQF_SAMPLE_RANDOM, 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 = device_create_file(&spi->dev,
+                                 gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
+        if (err)
+                goto err_remove_attr_group;
+
+        err = input_register_device(input_dev);
+        if (err)
+                goto err_remove_attr;
+
+        return 0;
+
+err_remove_attr:
+        device_remove_file(&spi->dev,
+                           gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
+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);
+        device_remove_file(&spi->dev,
+                           gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
+
+        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
+static int ad7877_suspend(struct spi_device *spi, pm_message_t message)
+{
+        struct ad7877 *ts = dev_get_drvdata(&spi->dev);
+
+        ad7877_disable(ts);
+
+        return 0;
+}
+
+static int ad7877_resume(struct spi_device *spi)
+{
+        struct ad7877 *ts = dev_get_drvdata(&spi->dev);
+
+        ad7877_enable(ts);
+
+        return 0;
+}
+#else
+#define ad7877_suspend NULL
+#define ad7877_resume  NULL
+#endif
+
+static struct spi_driver ad7877_driver = {
+        .driver = {
+                .name   = "ad7877",
+                .bus    = &spi_bus_type,
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ad7877_probe,
+        .remove         = __devexit_p(ad7877_remove),
+        .suspend        = ad7877_suspend,
+        .resume         = ad7877_resume,
+};
+
+static int __init ad7877_init(void)
+{
+        return spi_register_driver(&ad7877_driver);
+}
+module_init(ad7877_init);
+
+static void __exit ad7877_exit(void)
+{
+        spi_unregister_driver(&ad7877_driver);
+}
+module_exit(ad7877_exit);
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("AD7877 touchscreen Driver");
+MODULE_LICENSE("GPL");