Input: add AD7879 Touchscreen driver

[randy.dunlap@oracle.com: don't use bus_id]
[dtor@mail.ru: locking and other fixups]
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

3 files changed, 815 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index afeb7554bfe2..b01fd61dadcc 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -42,6 +42,38 @@ config TOUCHSCREEN_AD7877
           To compile this driver as a module, choose M here: the
           module will be called ad7877.
 
+config TOUCHSCREEN_AD7879_I2C
+        tristate "AD7879 based touchscreens: AD7879-1 I2C Interface"
+        depends on I2C
+        select TOUCHSCREEN_AD7879
+        help
+          Say Y here if you have a touchscreen interface using the
+          AD7879-1 controller, and your board-specific initialization
+          code includes that in its table of I2C 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 ad7879.
+
+config TOUCHSCREEN_AD7879_SPI
+        tristate "AD7879 based touchscreens: AD7879 SPI Interface"
+        depends on SPI_MASTER && TOUCHSCREEN_AD7879_I2C = n
+        select TOUCHSCREEN_AD7879
+        help
+          Say Y here if you have a touchscreen interface using the
+          AD7879 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 ad7879.
+
+config TOUCHSCREEN_AD7879
+        tristate
+        default n
+
 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 45dfcd61be11..6700f7b9d165 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -7,6 +7,7 @@
 wm97xx-ts-y := wm97xx-core.o
 
 obj-$(CONFIG_TOUCHSCREEN_AD7877)        += ad7877.o
+obj-$(CONFIG_TOUCHSCREEN_AD7879)        += ad7879.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/ad7879.c b/drivers/input/touchscreen/ad7879.c
new file mode 100644
index 000000000000..ea4c61d68683
--- /dev/null
+++ b/drivers/input/touchscreen/ad7879.c
@@ -0,0 +1,782 @@
+/*
+ * Copyright (C) 2008 Michael Hennerich, Analog Devices Inc.
+ *
+ * Description: AD7879 based touchscreen, and GPIO driver (I2C/SPI Interface)
+ *
+ * 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
+ *  - ad7877.c
+ *      Copyright (C) 2006-2008 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/spi/spi.h>
+#include <linux/i2c.h>
+
+#include <linux/spi/ad7879.h>
+
+#define AD7879_REG_ZEROS                0
+#define AD7879_REG_CTRL1                1
+#define AD7879_REG_CTRL2                2
+#define AD7879_REG_CTRL3                3
+#define AD7879_REG_AUX1HIGH             4
+#define AD7879_REG_AUX1LOW              5
+#define AD7879_REG_TEMP1HIGH            6
+#define AD7879_REG_TEMP1LOW             7
+#define AD7879_REG_XPLUS                8
+#define AD7879_REG_YPLUS                9
+#define AD7879_REG_Z1                   10
+#define AD7879_REG_Z2                   11
+#define AD7879_REG_AUXVBAT              12
+#define AD7879_REG_TEMP                 13
+#define AD7879_REG_REVID                14
+
+/* Control REG 1 */
+#define AD7879_TMR(x)                   ((x & 0xFF) << 0)
+#define AD7879_ACQ(x)                   ((x & 0x3) << 8)
+#define AD7879_MODE_NOC                 (0 << 10)       /* Do not convert */
+#define AD7879_MODE_SCC                 (1 << 10)       /* Single channel conversion */
+#define AD7879_MODE_SEQ0                (2 << 10)       /* Sequence 0 in Slave Mode */
+#define AD7879_MODE_SEQ1                (3 << 10)       /* Sequence 1 in Master Mode */
+#define AD7879_MODE_INT                 (1 << 15)       /* PENIRQ disabled INT enabled */
+
+/* Control REG 2 */
+#define AD7879_FCD(x)                   ((x & 0x3) << 0)
+#define AD7879_RESET                    (1 << 4)
+#define AD7879_MFS(x)                   ((x & 0x3) << 5)
+#define AD7879_AVG(x)                   ((x & 0x3) << 7)
+#define AD7879_SER                      (1 << 9)        /* non-differential */
+#define AD7879_DFR                      (0 << 9)        /* differential */
+#define AD7879_GPIOPOL                  (1 << 10)
+#define AD7879_GPIODIR                  (1 << 11)
+#define AD7879_GPIO_DATA                (1 << 12)
+#define AD7879_GPIO_EN                  (1 << 13)
+#define AD7879_PM(x)                    ((x & 0x3) << 14)
+#define AD7879_PM_SHUTDOWN              (0)
+#define AD7879_PM_DYN                   (1)
+#define AD7879_PM_FULLON                (2)
+
+/* Control REG 3 */
+#define AD7879_TEMPMASK_BIT             (1<<15)
+#define AD7879_AUXVBATMASK_BIT          (1<<14)
+#define AD7879_INTMODE_BIT              (1<<13)
+#define AD7879_GPIOALERTMASK_BIT        (1<<12)
+#define AD7879_AUXLOW_BIT               (1<<11)
+#define AD7879_AUXHIGH_BIT              (1<<10)
+#define AD7879_TEMPLOW_BIT              (1<<9)
+#define AD7879_TEMPHIGH_BIT             (1<<8)
+#define AD7879_YPLUS_BIT                (1<<7)
+#define AD7879_XPLUS_BIT                (1<<6)
+#define AD7879_Z1_BIT                   (1<<5)
+#define AD7879_Z2_BIT                   (1<<4)
+#define AD7879_AUX_BIT                  (1<<3)
+#define AD7879_VBAT_BIT                 (1<<2)
+#define AD7879_TEMP_BIT                 (1<<1)
+
+enum {
+        AD7879_SEQ_XPOS  = 0,
+        AD7879_SEQ_YPOS  = 1,
+        AD7879_SEQ_Z1    = 2,
+        AD7879_SEQ_Z2    = 3,
+        AD7879_NR_SENSE  = 4,
+};
+
+#define MAX_12BIT                       ((1<<12)-1)
+#define TS_PEN_UP_TIMEOUT               msecs_to_jiffies(50)
+
+#if defined(CONFIG_TOUCHSCREEN_AD7879_SPI) || defined(CONFIG_TOUCHSCREEN_AD7879_SPI_MODULE)
+#define AD7879_DEVID            0x7A
+typedef struct spi_device       bus_device;
+#elif defined(CONFIG_TOUCHSCREEN_AD7879_I2C) || defined(CONFIG_TOUCHSCREEN_AD7879_I2C_MODULE)
+#define AD7879_DEVID            0x79
+typedef struct i2c_client       bus_device;
+#endif
+
+struct ad7879 {
+        bus_device              *bus;
+        struct input_dev        *input;
+        struct work_struct      work;
+        struct timer_list       timer;
+
+        struct mutex            mutex;
+        unsigned                disabled:1;     /* P: mutex */
+
+#if defined(CONFIG_TOUCHSCREEN_AD7879_SPI) || defined(CONFIG_TOUCHSCREEN_AD7879_SPI_MODULE)
+        struct spi_message      msg;
+        struct spi_transfer     xfer[AD7879_NR_SENSE + 1];
+        u16                     cmd;
+#endif
+        u16                     conversion_data[AD7879_NR_SENSE];
+        char                    phys[32];
+        u8                      first_conversion_delay;
+        u8                      acquisition_time;
+        u8                      averaging;
+        u8                      pen_down_acc_interval;
+        u8                      median;
+        u16                     x_plate_ohms;
+        u16                     pressure_max;
+        u16                     gpio_init;
+        u16                     cmd_crtl1;
+        u16                     cmd_crtl2;
+        u16                     cmd_crtl3;
+        unsigned                gpio:1;
+};
+
+static int ad7879_read(bus_device *, u8);
+static int ad7879_write(bus_device *, u8, u16);
+static void ad7879_collect(struct ad7879 *);
+
+static void ad7879_report(struct ad7879 *ts)
+{
+        struct input_dev *input_dev = ts->input;
+        unsigned Rt;
+        u16 x, y, z1, z2;
+
+        x = ts->conversion_data[AD7879_SEQ_XPOS] & MAX_12BIT;
+        y = ts->conversion_data[AD7879_SEQ_YPOS] & MAX_12BIT;
+        z1 = ts->conversion_data[AD7879_SEQ_Z1] & MAX_12BIT;
+        z2 = ts->conversion_data[AD7879_SEQ_Z2] & MAX_12BIT;
+
+        /*
+         * The samples processed here are already preprocessed by the AD7879.
+         * The preprocessing function consists of a median and an averaging filter.
+         * The combination of these two techniques provides a robust solution,
+         * discarding the spurious noise in the signal and keeping only the data of interest.
+         * The size of both filters is programmable. (dev.platform_data, see linux/spi/ad7879.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 void ad7879_work(struct work_struct *work)
+{
+        struct ad7879 *ts = container_of(work, struct ad7879, work);
+
+        /* use keventd context to read the result registers */
+        ad7879_collect(ts);
+        ad7879_report(ts);
+        mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);
+}
+
+static void ad7879_ts_event_release(struct ad7879 *ts)
+{
+        struct input_dev *input_dev = ts->input;
+
+        input_report_abs(input_dev, ABS_PRESSURE, 0);
+        input_sync(input_dev);
+}
+
+static void ad7879_timer(unsigned long handle)
+{
+        struct ad7879 *ts = (void *)handle;
+
+        ad7879_ts_event_release(ts);
+}
+
+static irqreturn_t ad7879_irq(int irq, void *handle)
+{
+        struct ad7879 *ts = handle;
+
+        /* 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
+         */
+
+        if (!work_pending(&ts->work))
+                schedule_work(&ts->work);
+
+        return IRQ_HANDLED;
+}
+
+static void ad7879_setup(struct ad7879 *ts)
+{
+        ts->cmd_crtl3 = AD7879_YPLUS_BIT |
+                        AD7879_XPLUS_BIT |
+                        AD7879_Z2_BIT |
+                        AD7879_Z1_BIT |
+                        AD7879_TEMPMASK_BIT |
+                        AD7879_AUXVBATMASK_BIT |
+                        AD7879_GPIOALERTMASK_BIT;
+
+        ts->cmd_crtl2 = AD7879_PM(AD7879_PM_DYN) | AD7879_DFR |
+                        AD7879_AVG(ts->averaging) |
+                        AD7879_MFS(ts->median) |
+                        AD7879_FCD(ts->first_conversion_delay) |
+                        ts->gpio_init;
+
+        ts->cmd_crtl1 = AD7879_MODE_INT | AD7879_MODE_SEQ1 |
+                        AD7879_ACQ(ts->acquisition_time) |
+                        AD7879_TMR(ts->pen_down_acc_interval);
+
+        ad7879_write(ts->bus, AD7879_REG_CTRL2, ts->cmd_crtl2);
+        ad7879_write(ts->bus, AD7879_REG_CTRL3, ts->cmd_crtl3);
+        ad7879_write(ts->bus, AD7879_REG_CTRL1, ts->cmd_crtl1);
+}
+
+static void ad7879_disable(struct ad7879 *ts)
+{
+        mutex_lock(&ts->mutex);
+
+        if (!ts->disabled) {
+
+                ts->disabled = 1;
+                disable_irq(ts->bus->irq);
+
+                cancel_work_sync(&ts->work);
+
+                if (del_timer_sync(&ts->timer))
+                        ad7879_ts_event_release(ts);
+
+                ad7879_write(ts->bus, AD7879_REG_CTRL2,
+                             AD7879_PM(AD7879_PM_SHUTDOWN));
+        }
+
+        mutex_unlock(&ts->mutex);
+}
+
+static void ad7879_enable(struct ad7879 *ts)
+{
+        mutex_lock(&ts->mutex);
+
+        if (ts->disabled) {
+                ad7879_setup(ts);
+                ts->disabled = 0;
+                enable_irq(ts->bus->irq);
+        }
+
+        mutex_unlock(&ts->mutex);
+}
+
+static ssize_t ad7879_disable_show(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+        struct ad7879 *ts = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%u\n", ts->disabled);
+}
+
+static ssize_t ad7879_disable_store(struct device *dev,
+                                     struct device_attribute *attr,
+                                     const char *buf, size_t count)
+{
+        struct ad7879 *ts = dev_get_drvdata(dev);
+        unsigned long val;
+        int error;
+
+        error = strict_strtoul(buf, 10, &val);
+        if (error)
+                return error;
+
+        if (val)
+                ad7879_disable(ts);
+        else
+                ad7879_enable(ts);
+
+        return count;
+}
+
+static DEVICE_ATTR(disable, 0664, ad7879_disable_show, ad7879_disable_store);
+
+static ssize_t ad7879_gpio_show(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+        struct ad7879 *ts = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%u\n", ts->gpio);
+}
+
+static ssize_t ad7879_gpio_store(struct device *dev,
+                                     struct device_attribute *attr,
+                                     const char *buf, size_t count)
+{
+        struct ad7879 *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->gpio = !!val;
+        error = ad7879_write(ts->bus, AD7879_REG_CTRL2,
+                           ts->gpio ?
+                                ts->cmd_crtl2 & ~AD7879_GPIO_DATA :
+                                ts->cmd_crtl2 | AD7879_GPIO_DATA);
+        mutex_unlock(&ts->mutex);
+
+        return error ? : count;
+}
+
+static DEVICE_ATTR(gpio, 0664, ad7879_gpio_show, ad7879_gpio_store);
+
+static struct attribute *ad7879_attributes[] = {
+        &dev_attr_disable.attr,
+        &dev_attr_gpio.attr,
+        NULL
+};
+
+static const struct attribute_group ad7879_attr_group = {
+        .attrs = ad7879_attributes,
+};
+
+static int __devinit ad7879_construct(bus_device *bus, struct ad7879 *ts)
+{
+        struct input_dev *input_dev;
+        struct ad7879_platform_data *pdata = bus->dev.platform_data;
+        int err;
+        u16 revid;
+
+        if (!bus->irq) {
+                dev_err(&bus->dev, "no IRQ?\n");
+                return -ENODEV;
+        }
+
+        if (!pdata) {
+                dev_err(&bus->dev, "no platform data?\n");
+                return -ENODEV;
+        }
+
+        input_dev = input_allocate_device();
+        if (!input_dev)
+                return -ENOMEM;
+
+        ts->input = input_dev;
+
+        setup_timer(&ts->timer, ad7879_timer, (unsigned long) ts);
+        INIT_WORK(&ts->work, ad7879_work);
+        mutex_init(&ts->mutex);
+
+        ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
+        ts->pressure_max = pdata->pressure_max ? : ~0;
+
+        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;
+        ts->median = pdata->median;
+
+        if (pdata->gpio_output)
+                ts->gpio_init = AD7879_GPIO_EN |
+                                (pdata->gpio_default ? 0 : AD7879_GPIO_DATA);
+        else
+                ts->gpio_init = AD7879_GPIO_EN | AD7879_GPIODIR;
+
+        snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&bus->dev));
+
+        input_dev->name = "AD7879 Touchscreen";
+        input_dev->phys = ts->phys;
+        input_dev->dev.parent = &bus->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);
+
+        err = ad7879_write(bus, AD7879_REG_CTRL2, AD7879_RESET);
+
+        if (err < 0) {
+                dev_err(&bus->dev, "Failed to write %s\n", input_dev->name);
+                goto err_free_mem;
+        }
+
+        revid = ad7879_read(bus, AD7879_REG_REVID);
+
+        if ((revid & 0xFF) != AD7879_DEVID) {
+                dev_err(&bus->dev, "Failed to probe %s\n", input_dev->name);
+                err = -ENODEV;
+                goto err_free_mem;
+        }
+
+        ad7879_setup(ts);
+
+        err = request_irq(bus->irq, ad7879_irq,
+                          IRQF_TRIGGER_FALLING | IRQF_SAMPLE_RANDOM,
+                          bus->dev.driver->name, ts);
+
+        if (err) {
+                dev_err(&bus->dev, "irq %d busy?\n", bus->irq);
+                goto err_free_mem;
+        }
+
+        err = sysfs_create_group(&bus->dev.kobj, &ad7879_attr_group);
+        if (err)
+                goto err_free_irq;
+
+        err = input_register_device(input_dev);
+        if (err)
+                goto err_remove_attr;
+
+        dev_info(&bus->dev, "Rev.%d touchscreen, irq %d\n",
+                 revid >> 8, bus->irq);
+
+        return 0;
+
+err_remove_attr:
+        sysfs_remove_group(&bus->dev.kobj, &ad7879_attr_group);
+err_free_irq:
+        free_irq(bus->irq, ts);
+err_free_mem:
+        input_free_device(input_dev);
+
+        return err;
+}
+
+static int __devexit ad7879_destroy(bus_device *bus, struct ad7879 *ts)
+{
+        ad7879_disable(ts);
+        sysfs_remove_group(&ts->bus->dev.kobj, &ad7879_attr_group);
+        free_irq(ts->bus->irq, ts);
+        input_unregister_device(ts->input);
+        dev_dbg(&bus->dev, "unregistered touchscreen\n");
+
+        return 0;
+}
+
+#ifdef CONFIG_PM
+static int ad7879_suspend(bus_device *bus, pm_message_t message)
+{
+        struct ad7879 *ts = dev_get_drvdata(&bus->dev);
+
+        ad7879_disable(ts);
+
+        return 0;
+}
+
+static int ad7879_resume(bus_device *bus)
+{
+        struct ad7879 *ts = dev_get_drvdata(&bus->dev);
+
+        ad7879_enable(ts);
+
+        return 0;
+}
+#else
+#define ad7879_suspend NULL
+#define ad7879_resume  NULL
+#endif
+
+#if defined(CONFIG_TOUCHSCREEN_AD7879_SPI) || defined(CONFIG_TOUCHSCREEN_AD7879_SPI_MODULE)
+#define MAX_SPI_FREQ_HZ         5000000
+#define AD7879_CMD_MAGIC        0xE000
+#define AD7879_CMD_READ         (1 << 10)
+#define AD7879_WRITECMD(reg)    (AD7879_CMD_MAGIC | (reg & 0xF))
+#define AD7879_READCMD(reg)     (AD7879_CMD_MAGIC | AD7879_CMD_READ | (reg & 0xF))
+
+struct ser_req {
+        u16                     command;
+        u16                     data;
+        struct spi_message      msg;
+        struct spi_transfer     xfer[2];
+};
+
+/*
+ * ad7879_read/write are only used for initial setup and for sysfs controls.
+ * The main traffic is done in ad7879_collect().
+ */
+
+static int ad7879_read(struct spi_device *spi, u8 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) AD7879_READCMD(reg);
+        req->xfer[0].tx_buf = &req->command;
+        req->xfer[0].len = 2;
+
+        req->xfer[1].rx_buf = &req->data;
+        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->data;
+
+        kfree(req);
+
+        return ret;
+}
+
+static int ad7879_write(struct spi_device *spi, u8 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) AD7879_WRITECMD(reg);
+        req->xfer[0].tx_buf = &req->command;
+        req->xfer[0].len = 2;
+
+        req->data = val;
+        req->xfer[1].tx_buf = &req->data;
+        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);
+
+        kfree(req);
+
+        return status;
+}
+
+static void ad7879_collect(struct ad7879 *ts)
+{
+        int status = spi_sync(ts->bus, &ts->msg);
+
+        if (status)
+                dev_err(&ts->bus->dev, "spi_sync --> %d\n", status);
+}
+
+static void ad7879_setup_ts_def_msg(struct ad7879 *ts)
+{
+        struct spi_message *m;
+        int i;
+
+        ts->cmd = (u16) AD7879_READCMD(AD7879_REG_XPLUS);
+
+        m = &ts->msg;
+        spi_message_init(m);
+        ts->xfer[0].tx_buf = &ts->cmd;
+        ts->xfer[0].len = 2;
+
+        spi_message_add_tail(&ts->xfer[0], m);
+
+        for (i = 0; i < AD7879_NR_SENSE; i++) {
+                ts->xfer[i + 1].rx_buf = &ts->conversion_data[i];
+                ts->xfer[i + 1].len = 2;
+                spi_message_add_tail(&ts->xfer[i + 1], m);
+        }
+}
+
+static int __devinit ad7879_probe(struct spi_device *spi)
+{
+        struct ad7879 *ts;
+        int error;
+
+        /* don't exceed max specified SPI CLK frequency */
+        if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
+                dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
+                return -EINVAL;
+        }
+
+        ts = kzalloc(sizeof(struct ad7879), GFP_KERNEL);
+        if (!ts)
+                return -ENOMEM;
+
+        dev_set_drvdata(&spi->dev, ts);
+        ts->bus = spi;
+
+        ad7879_setup_ts_def_msg(ts);
+
+        error = ad7879_construct(spi, ts);
+        if (error) {
+                dev_set_drvdata(&spi->dev, NULL);
+                kfree(ts);
+        }
+
+        return 0;
+}
+
+static int __devexit ad7879_remove(struct spi_device *spi)
+{
+        struct ad7879 *ts = dev_get_drvdata(&spi->dev);
+
+        ad7879_destroy(spi, ts);
+        dev_set_drvdata(&spi->dev, NULL);
+        kfree(ts);
+
+        return 0;
+}
+
+static struct spi_driver ad7879_driver = {
+        .driver = {
+                .name   = "ad7879",
+                .bus    = &spi_bus_type,
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ad7879_probe,
+        .remove         = __devexit_p(ad7879_remove),
+        .suspend        = ad7879_suspend,
+        .resume         = ad7879_resume,
+};
+
+static int __init ad7879_init(void)
+{
+        return spi_register_driver(&ad7879_driver);
+}
+module_init(ad7879_init);
+
+static void __exit ad7879_exit(void)
+{
+        spi_unregister_driver(&ad7879_driver);
+}
+module_exit(ad7879_exit);
+
+#elif defined(CONFIG_TOUCHSCREEN_AD7879_I2C) || defined(CONFIG_TOUCHSCREEN_AD7879_I2C_MODULE)
+
+/* All registers are word-sized.
+ * AD7879 uses a high-byte first convention.
+ */
+static int ad7879_read(struct i2c_client *client, u8 reg)
+{
+        return swab16(i2c_smbus_read_word_data(client, reg));
+}
+
+static int ad7879_write(struct i2c_client *client, u8 reg, u16 val)
+{
+        return i2c_smbus_write_word_data(client, reg, swab16(val));
+}
+
+static void ad7879_collect(struct ad7879 *ts)
+{
+        int i;
+
+        for (i = 0; i < AD7879_NR_SENSE; i++)
+                ts->conversion_data[i] = ad7879_read(ts->bus,
+                                                     AD7879_REG_XPLUS + i);
+}
+
+static int __devinit ad7879_probe(struct i2c_client *client,
+                                        const struct i2c_device_id *id)
+{
+        struct ad7879 *ts;
+        int error;
+
+        if (!i2c_check_functionality(client->adapter,
+                                        I2C_FUNC_SMBUS_WORD_DATA)) {
+                dev_err(&client->dev, "SMBUS Word Data not Supported\n");
+                return -EIO;
+        }
+
+        ts = kzalloc(sizeof(struct ad7879), GFP_KERNEL);
+        if (!ts)
+                return -ENOMEM;
+
+        i2c_set_clientdata(client, ts);
+        ts->bus = client;
+
+        error = ad7879_construct(client, ts);
+        if (error) {
+                i2c_set_clientdata(client, NULL);
+                kfree(ts);
+        }
+
+        return 0;
+}
+
+static int __devexit ad7879_remove(struct i2c_client *client)
+{
+        struct ad7879 *ts = dev_get_drvdata(&client->dev);
+
+        ad7879_destroy(client, ts);
+        i2c_set_clientdata(client, NULL);
+        kfree(ts);
+
+        return 0;
+}
+
+static const struct i2c_device_id ad7879_id[] = {
+        { "ad7879", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, ad7879_id);
+
+static struct i2c_driver ad7879_driver = {
+        .driver = {
+                .name   = "ad7879",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ad7879_probe,
+        .remove         = __devexit_p(ad7879_remove),
+        .suspend        = ad7879_suspend,
+        .resume         = ad7879_resume,
+        .id_table       = ad7879_id,
+};
+
+static int __init ad7879_init(void)
+{
+        return i2c_add_driver(&ad7879_driver);
+}
+module_init(ad7879_init);
+
+static void __exit ad7879_exit(void)
+{
+        i2c_del_driver(&ad7879_driver);
+}
+module_exit(ad7879_exit);
+#endif
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("AD7879(-1) touchscreen Driver");
+MODULE_LICENSE("GPL");