Input: add Analog Devices AD714x captouch input driver

AD7142 and AD7147 are integrated capacitance-to-digital converters
(CDCs) with on-chip environmental calibration for use in systems
requiring a novel user input method. The AD7142 and AD7147 can interface
to external capacitance sensors implementing functions such as buttons,
scrollwheels, sliders, touchpads and so on.

The chips don't restrict the specific usage. Depending on the hardware
connection, one special target board can include one or several these
components. The platform_data for the device's "struct device" holds
these information. The data-struct defined in head file descript the
hardware feature of button/scrollwheel/slider/touchpad components on
target boards, which need be filled in the arch/mach-/.

As the result, the driver is independent of boards. It gets the
components layout from the platform_data, registers related devices,
fullfills the algorithms and state machines for these components and
report related input events to up level.

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Barry Song <21cnbao@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 1331 insertions, 0 deletions

diff --git a/drivers/input/misc/ad714x.c b/drivers/input/misc/ad714x.c
new file mode 100644
index 000000000000..691b1d37331f
--- /dev/null
+++ b/drivers/input/misc/ad714x.c
@@ -0,0 +1,1331 @@
+/*
+ * AD714X CapTouch Programmable Controller driver
+ *
+ * Copyright 2009 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/input/ad714x.h>
+#include "ad714x.h"
+
+#define AD714X_PWR_CTRL           0x0
+#define AD714X_STG_CAL_EN_REG     0x1
+#define AD714X_AMB_COMP_CTRL0_REG 0x2
+#define AD714X_PARTID_REG         0x17
+#define AD7147_PARTID             0x1470
+#define AD7142_PARTID             0xE620
+#define AD714X_STAGECFG_REG       0x80
+#define AD714X_SYSCFG_REG         0x0
+
+#define STG_LOW_INT_EN_REG     0x5
+#define STG_HIGH_INT_EN_REG    0x6
+#define STG_COM_INT_EN_REG     0x7
+#define STG_LOW_INT_STA_REG    0x8
+#define STG_HIGH_INT_STA_REG   0x9
+#define STG_COM_INT_STA_REG    0xA
+
+#define CDC_RESULT_S0          0xB
+#define CDC_RESULT_S1          0xC
+#define CDC_RESULT_S2          0xD
+#define CDC_RESULT_S3          0xE
+#define CDC_RESULT_S4          0xF
+#define CDC_RESULT_S5          0x10
+#define CDC_RESULT_S6          0x11
+#define CDC_RESULT_S7          0x12
+#define CDC_RESULT_S8          0x13
+#define CDC_RESULT_S9          0x14
+#define CDC_RESULT_S10         0x15
+#define CDC_RESULT_S11         0x16
+
+#define STAGE0_AMBIENT		0xF1
+#define STAGE1_AMBIENT		0x115
+#define STAGE2_AMBIENT		0x139
+#define STAGE3_AMBIENT		0x15D
+#define STAGE4_AMBIENT		0x181
+#define STAGE5_AMBIENT		0x1A5
+#define STAGE6_AMBIENT		0x1C9
+#define STAGE7_AMBIENT		0x1ED
+#define STAGE8_AMBIENT		0x211
+#define STAGE9_AMBIENT		0x234
+#define STAGE10_AMBIENT		0x259
+#define STAGE11_AMBIENT		0x27D
+
+#define PER_STAGE_REG_NUM      36
+#define STAGE_NUM              12
+#define STAGE_CFGREG_NUM       8
+#define SYS_CFGREG_NUM         8
+
+/*
+ * driver information which will be used to maintain the software flow
+ */
+enum ad714x_device_state { IDLE, JITTER, ACTIVE, SPACE };
+
+struct ad714x_slider_drv {
+	int highest_stage;
+	int abs_pos;
+	int flt_pos;
+	enum ad714x_device_state state;
+	struct input_dev *input;
+};
+
+struct ad714x_wheel_drv {
+	int abs_pos;
+	int flt_pos;
+	int pre_mean_value;
+	int pre_highest_stage;
+	int pre_mean_value_no_offset;
+	int mean_value;
+	int mean_value_no_offset;
+	int pos_offset;
+	int pos_ratio;
+	int highest_stage;
+	enum ad714x_device_state state;
+	struct input_dev *input;
+};
+
+struct ad714x_touchpad_drv {
+	int x_highest_stage;
+	int x_flt_pos;
+	int x_abs_pos;
+	int y_highest_stage;
+	int y_flt_pos;
+	int y_abs_pos;
+	int left_ep;
+	int left_ep_val;
+	int right_ep;
+	int right_ep_val;
+	int top_ep;
+	int top_ep_val;
+	int bottom_ep;
+	int bottom_ep_val;
+	enum ad714x_device_state state;
+	struct input_dev *input;
+};
+
+struct ad714x_button_drv {
+	enum ad714x_device_state state;
+	/*
+	 * Unlike slider/wheel/touchpad, all buttons point to
+	 * same input_dev instance
+	 */
+	struct input_dev *input;
+};
+
+struct ad714x_driver_data {
+	struct ad714x_slider_drv *slider;
+	struct ad714x_wheel_drv *wheel;
+	struct ad714x_touchpad_drv *touchpad;
+	struct ad714x_button_drv *button;
+};
+
+/*
+ * information to integrate all things which will be private data
+ * of spi/i2c device
+ */
+struct ad714x_chip {
+	unsigned short h_state;
+	unsigned short l_state;
+	unsigned short c_state;
+	unsigned short adc_reg[STAGE_NUM];
+	unsigned short amb_reg[STAGE_NUM];
+	unsigned short sensor_val[STAGE_NUM];
+
+	struct ad714x_platform_data *hw;
+	struct ad714x_driver_data *sw;
+
+	int irq;
+	struct device *dev;
+	ad714x_read_t read;
+	ad714x_write_t write;
+
+	struct mutex mutex;
+
+	unsigned product;
+	unsigned version;
+};
+
+static void ad714x_use_com_int(struct ad714x_chip *ad714x,
+				int start_stage, int end_stage)
+{
+	unsigned short data;
+	unsigned short mask;
+
+	mask = ((1 << (end_stage + 1)) - 1) - (1 << start_stage);
+
+	ad714x->read(ad714x->dev, STG_COM_INT_EN_REG, &data);
+	data |= 1 << start_stage;
+	ad714x->write(ad714x->dev, STG_COM_INT_EN_REG, data);
+
+	ad714x->read(ad714x->dev, STG_HIGH_INT_EN_REG, &data);
+	data &= ~mask;
+	ad714x->write(ad714x->dev, STG_HIGH_INT_EN_REG, data);
+}
+
+static void ad714x_use_thr_int(struct ad714x_chip *ad714x,
+				int start_stage, int end_stage)
+{
+	unsigned short data;
+	unsigned short mask;
+
+	mask = ((1 << (end_stage + 1)) - 1) - (1 << start_stage);
+
+	ad714x->read(ad714x->dev, STG_COM_INT_EN_REG, &data);
+	data &= ~(1 << start_stage);
+	ad714x->write(ad714x->dev, STG_COM_INT_EN_REG, data);
+
+	ad714x->read(ad714x->dev, STG_HIGH_INT_EN_REG, &data);
+	data |= mask;
+	ad714x->write(ad714x->dev, STG_HIGH_INT_EN_REG, data);
+}
+
+static int ad714x_cal_highest_stage(struct ad714x_chip *ad714x,
+					int start_stage, int end_stage)
+{
+	int max_res = 0;
+	int max_idx = 0;
+	int i;
+
+	for (i = start_stage; i <= end_stage; i++) {
+		if (ad714x->sensor_val[i] > max_res) {
+			max_res = ad714x->sensor_val[i];
+			max_idx = i;
+		}
+	}
+
+	return max_idx;
+}
+
+static int ad714x_cal_abs_pos(struct ad714x_chip *ad714x,
+				int start_stage, int end_stage,
+				int highest_stage, int max_coord)
+{
+	int a_param, b_param;
+
+	if (highest_stage == start_stage) {
+		a_param = ad714x->sensor_val[start_stage + 1];
+		b_param = ad714x->sensor_val[start_stage] +
+			ad714x->sensor_val[start_stage + 1];
+	} else if (highest_stage == end_stage) {
+		a_param = ad714x->sensor_val[end_stage] *
+			(end_stage - start_stage) +
+			ad714x->sensor_val[end_stage - 1] *
+			(end_stage - start_stage - 1);
+		b_param = ad714x->sensor_val[end_stage] +
+			ad714x->sensor_val[end_stage - 1];
+	} else {
+		a_param = ad714x->sensor_val[highest_stage] *
+			(highest_stage - start_stage) +
+			ad714x->sensor_val[highest_stage - 1] *
+			(highest_stage - start_stage - 1) +
+			ad714x->sensor_val[highest_stage + 1] *
+			(highest_stage - start_stage + 1);
+		b_param = ad714x->sensor_val[highest_stage] +
+			ad714x->sensor_val[highest_stage - 1] +
+			ad714x->sensor_val[highest_stage + 1];
+	}
+
+	return (max_coord / (end_stage - start_stage)) * a_param / b_param;
+}
+
+/*
+ * One button can connect to multi positive and negative of CDCs
+ * Multi-buttons can connect to same positive/negative of one CDC
+ */
+static void ad714x_button_state_machine(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_button_plat *hw = &ad714x->hw->button[idx];
+	struct ad714x_button_drv *sw = &ad714x->sw->button[idx];
+
+	switch (sw->state) {
+	case IDLE:
+		if (((ad714x->h_state & hw->h_mask) == hw->h_mask) &&
+		    ((ad714x->l_state & hw->l_mask) == hw->l_mask)) {
+			dev_dbg(ad714x->dev, "button %d touched\n", idx);
+			input_report_key(sw->input, hw->keycode, 1);
+			input_sync(sw->input);
+			sw->state = ACTIVE;
+		}
+		break;
+
+	case ACTIVE:
+		if (((ad714x->h_state & hw->h_mask) != hw->h_mask) ||
+		    ((ad714x->l_state & hw->l_mask) != hw->l_mask)) {
+			dev_dbg(ad714x->dev, "button %d released\n", idx);
+			input_report_key(sw->input, hw->keycode, 0);
+			input_sync(sw->input);
+			sw->state = IDLE;
+		}
+		break;
+
+	default:
+		break;
+	}
+}
+
+/*
+ * The response of a sensor is defined by the absolute number of codes
+ * between the current CDC value and the ambient value.
+ */
+static void ad714x_slider_cal_sensor_val(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+	int i;
+
+	for (i = hw->start_stage; i <= hw->end_stage; i++) {
+		ad714x->read(ad714x->dev, CDC_RESULT_S0 + i,
+			&ad714x->adc_reg[i]);
+		ad714x->read(ad714x->dev,
+				STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
+				&ad714x->amb_reg[i]);
+
+		ad714x->sensor_val[i] = abs(ad714x->adc_reg[i] -
+				ad714x->amb_reg[i]);
+	}
+}
+
+static void ad714x_slider_cal_highest_stage(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+	struct ad714x_slider_drv *sw = &ad714x->sw->slider[idx];
+
+	sw->highest_stage = ad714x_cal_highest_stage(ad714x, hw->start_stage,
+			hw->end_stage);
+
+	dev_dbg(ad714x->dev, "slider %d highest_stage:%d\n", idx,
+		sw->highest_stage);
+}
+
+/*
+ * The formulae are very straight forward. It uses the sensor with the
+ * highest response and the 2 adjacent ones.
+ * When Sensor 0 has the highest response, only sensor 0 and sensor 1
+ * are used in the calculations. Similarly when the last sensor has the
+ * highest response, only the last sensor and the second last sensors
+ * are used in the calculations.
+ *
+ * For i= idx_of_peak_Sensor-1 to i= idx_of_peak_Sensor+1
+ *         v += Sensor response(i)*i
+ *         w += Sensor response(i)
+ * POS=(Number_of_Positions_Wanted/(Number_of_Sensors_Used-1)) *(v/w)
+ */
+static void ad714x_slider_cal_abs_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+	struct ad714x_slider_drv *sw = &ad714x->sw->slider[idx];
+
+	sw->abs_pos = ad714x_cal_abs_pos(ad714x, hw->start_stage, hw->end_stage,
+		sw->highest_stage, hw->max_coord);
+
+	dev_dbg(ad714x->dev, "slider %d absolute position:%d\n", idx,
+		sw->abs_pos);
+}
+
+/*
+ * To minimise the Impact of the noise on the algorithm, ADI developed a
+ * routine that filters the CDC results after they have been read by the
+ * host processor.
+ * The filter used is an Infinite Input Response(IIR) filter implemented
+ * in firmware and attenuates the noise on the CDC results after they've
+ * been read by the host processor.
+ * Filtered_CDC_result = (Filtered_CDC_result * (10 - Coefficient) +
+ *				Latest_CDC_result * Coefficient)/10
+ */
+static void ad714x_slider_cal_flt_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_drv *sw = &ad714x->sw->slider[idx];
+
+	sw->flt_pos = (sw->flt_pos * (10 - 4) +
+			sw->abs_pos * 4)/10;
+
+	dev_dbg(ad714x->dev, "slider %d filter position:%d\n", idx,
+		sw->flt_pos);
+}
+
+static void ad714x_slider_use_com_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+
+	ad714x_use_com_int(ad714x, hw->start_stage, hw->end_stage);
+}
+
+static void ad714x_slider_use_thr_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+
+	ad714x_use_thr_int(ad714x, hw->start_stage, hw->end_stage);
+}
+
+static void ad714x_slider_state_machine(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_slider_plat *hw = &ad714x->hw->slider[idx];
+	struct ad714x_slider_drv *sw = &ad714x->sw->slider[idx];
+	unsigned short h_state, c_state;
+	unsigned short mask;
+
+	mask = ((1 << (hw->end_stage + 1)) - 1) - ((1 << hw->start_stage) - 1);
+
+	h_state = ad714x->h_state & mask;
+	c_state = ad714x->c_state & mask;
+
+	switch (sw->state) {
+	case IDLE:
+		if (h_state) {
+			sw->state = JITTER;
+			/* In End of Conversion interrupt mode, the AD714X
+			 * continuously generates hardware interrupts.
+			 */
+			ad714x_slider_use_com_int(ad714x, idx);
+			dev_dbg(ad714x->dev, "slider %d touched\n", idx);
+		}
+		break;
+
+	case JITTER:
+		if (c_state == mask) {
+			ad714x_slider_cal_sensor_val(ad714x, idx);
+			ad714x_slider_cal_highest_stage(ad714x, idx);
+			ad714x_slider_cal_abs_pos(ad714x, idx);
+			sw->flt_pos = sw->abs_pos;
+			sw->state = ACTIVE;
+		}
+		break;
+
+	case ACTIVE:
+		if (c_state == mask) {
+			if (h_state) {
+				ad714x_slider_cal_sensor_val(ad714x, idx);
+				ad714x_slider_cal_highest_stage(ad714x, idx);
+				ad714x_slider_cal_abs_pos(ad714x, idx);
+				ad714x_slider_cal_flt_pos(ad714x, idx);
+
+				input_report_abs(sw->input, ABS_X, sw->flt_pos);
+				input_report_key(sw->input, BTN_TOUCH, 1);
+			} else {
+				/* When the user lifts off the sensor, configure
+				 * the AD714X back to threshold interrupt mode.
+				 */
+				ad714x_slider_use_thr_int(ad714x, idx);
+				sw->state = IDLE;
+				input_report_key(sw->input, BTN_TOUCH, 0);
+				dev_dbg(ad714x->dev, "slider %d released\n",
+					idx);
+			}
+			input_sync(sw->input);
+		}
+		break;
+
+	default:
+		break;
+	}
+}
+
+/*
+ * When the scroll wheel is activated, we compute the absolute position based
+ * on the sensor values. To calculate the position, we first determine the
+ * sensor that has the greatest response among the 8 sensors that constitutes
+ * the scrollwheel. Then we determined the 2 sensors on either sides of the
+ * sensor with the highest response and we apply weights to these sensors.
+ */
+static void ad714x_wheel_cal_highest_stage(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+	struct ad714x_wheel_drv *sw = &ad714x->sw->wheel[idx];
+
+	sw->pre_highest_stage = sw->highest_stage;
+	sw->highest_stage = ad714x_cal_highest_stage(ad714x, hw->start_stage,
+			hw->end_stage);
+
+	dev_dbg(ad714x->dev, "wheel %d highest_stage:%d\n", idx,
+		sw->highest_stage);
+}
+
+static void ad714x_wheel_cal_sensor_val(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+	int i;
+
+	for (i = hw->start_stage; i <= hw->end_stage; i++) {
+		ad714x->read(ad714x->dev, CDC_RESULT_S0 + i,
+			&ad714x->adc_reg[i]);
+		ad714x->read(ad714x->dev,
+				STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
+				&ad714x->amb_reg[i]);
+		if (ad714x->adc_reg[i] > ad714x->amb_reg[i])
+			ad714x->sensor_val[i] = ad714x->adc_reg[i] -
+				ad714x->amb_reg[i];
+		else
+			ad714x->sensor_val[i] = 0;
+	}
+}
+
+/*
+ * When the scroll wheel is activated, we compute the absolute position based
+ * on the sensor values. To calculate the position, we first determine the
+ * sensor that has the greatest response among the 8 sensors that constitutes
+ * the scrollwheel. Then we determined the 2 sensors on either sides of the
+ * sensor with the highest response and we apply weights to these sensors. The
+ * result of this computation gives us the mean value which defined by the
+ * following formula:
+ * For i= second_before_highest_stage to i= second_after_highest_stage
+ *         v += Sensor response(i)*WEIGHT*(i+3)
+ *         w += Sensor response(i)
+ * Mean_Value=v/w
+ * pos_on_scrollwheel = (Mean_Value - position_offset) / position_ratio
+ */
+
+#define WEIGHT_FACTOR 30
+/* This constant prevents the "PositionOffset" from reaching a big value */
+#define OFFSET_POSITION_CLAMP	120
+static void ad714x_wheel_cal_abs_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+	struct ad714x_wheel_drv *sw = &ad714x->sw->wheel[idx];
+	int stage_num = hw->end_stage - hw->start_stage + 1;
+	int second_before, first_before, highest, first_after, second_after;
+	int a_param, b_param;
+
+	/* Calculate Mean value */
+
+	second_before = (sw->highest_stage + stage_num - 2) % stage_num;
+	first_before = (sw->highest_stage + stage_num - 1) % stage_num;
+	highest = sw->highest_stage;
+	first_after = (sw->highest_stage + stage_num + 1) % stage_num;
+	second_after = (sw->highest_stage + stage_num + 2) % stage_num;
+
+	if (((sw->highest_stage - hw->start_stage) > 1) &&
+	    ((hw->end_stage - sw->highest_stage) > 1)) {
+		a_param = ad714x->sensor_val[second_before] *
+			(second_before - hw->start_stage + 3) +
+			ad714x->sensor_val[first_before] *
+			(second_before - hw->start_stage + 3) +
+			ad714x->sensor_val[highest] *
+			(second_before - hw->start_stage + 3) +
+			ad714x->sensor_val[first_after] *
+			(first_after - hw->start_stage + 3) +
+			ad714x->sensor_val[second_after] *
+			(second_after - hw->start_stage + 3);
+	} else {
+		a_param = ad714x->sensor_val[second_before] *
+			(second_before - hw->start_stage + 1) +
+			ad714x->sensor_val[first_before] *
+			(second_before - hw->start_stage + 2) +
+			ad714x->sensor_val[highest] *
+			(second_before - hw->start_stage + 3) +
+			ad714x->sensor_val[first_after] *
+			(first_after - hw->start_stage + 4) +
+			ad714x->sensor_val[second_after] *
+			(second_after - hw->start_stage + 5);
+	}
+	a_param *= WEIGHT_FACTOR;
+
+	b_param = ad714x->sensor_val[second_before] +
+		ad714x->sensor_val[first_before] +
+		ad714x->sensor_val[highest] +
+		ad714x->sensor_val[first_after] +
+		ad714x->sensor_val[second_after];
+
+	sw->pre_mean_value = sw->mean_value;
+	sw->mean_value = a_param / b_param;
+
+	/* Calculate the offset */
+
+	if ((sw->pre_highest_stage == hw->end_stage) &&
+			(sw->highest_stage == hw->start_stage))
+		sw->pos_offset = sw->mean_value;
+	else if ((sw->pre_highest_stage == hw->start_stage) &&
+			(sw->highest_stage == hw->end_stage))
+		sw->pos_offset = sw->pre_mean_value;
+
+	if (sw->pos_offset > OFFSET_POSITION_CLAMP)
+		sw->pos_offset = OFFSET_POSITION_CLAMP;
+
+	/* Calculate the mean value without the offset */
+
+	sw->pre_mean_value_no_offset = sw->mean_value_no_offset;
+	sw->mean_value_no_offset = sw->mean_value - sw->pos_offset;
+	if (sw->mean_value_no_offset < 0)
+		sw->mean_value_no_offset = 0;
+
+	/* Calculate ratio to scale down to NUMBER_OF_WANTED_POSITIONS */
+
+	if ((sw->pre_highest_stage == hw->end_stage) &&
+			(sw->highest_stage == hw->start_stage))
+		sw->pos_ratio = (sw->pre_mean_value_no_offset * 100) /
+			hw->max_coord;
+	else if ((sw->pre_highest_stage == hw->start_stage) &&
+			(sw->highest_stage == hw->end_stage))
+		sw->pos_ratio = (sw->mean_value_no_offset * 100) /
+			hw->max_coord;
+	sw->abs_pos = (sw->mean_value_no_offset * 100) / sw->pos_ratio;
+	if (sw->abs_pos > hw->max_coord)
+		sw->abs_pos = hw->max_coord;
+}
+
+static void ad714x_wheel_cal_flt_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+	struct ad714x_wheel_drv *sw = &ad714x->sw->wheel[idx];
+	if (((sw->pre_highest_stage == hw->end_stage) &&
+			(sw->highest_stage == hw->start_stage)) ||
+	    ((sw->pre_highest_stage == hw->start_stage) &&
+			(sw->highest_stage == hw->end_stage)))
+		sw->flt_pos = sw->abs_pos;
+	else
+		sw->flt_pos = ((sw->flt_pos * 30) + (sw->abs_pos * 71)) / 100;
+
+	if (sw->flt_pos > hw->max_coord)
+		sw->flt_pos = hw->max_coord;
+}
+
+static void ad714x_wheel_use_com_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+
+	ad714x_use_com_int(ad714x, hw->start_stage, hw->end_stage);
+}
+
+static void ad714x_wheel_use_thr_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+
+	ad714x_use_thr_int(ad714x, hw->start_stage, hw->end_stage);
+}
+
+static void ad714x_wheel_state_machine(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_wheel_plat *hw = &ad714x->hw->wheel[idx];
+	struct ad714x_wheel_drv *sw = &ad714x->sw->wheel[idx];
+	unsigned short h_state, c_state;
+	unsigned short mask;
+
+	mask = ((1 << (hw->end_stage + 1)) - 1) - ((1 << hw->start_stage) - 1);
+
+	h_state = ad714x->h_state & mask;
+	c_state = ad714x->c_state & mask;
+
+	switch (sw->state) {
+	case IDLE:
+		if (h_state) {
+			sw->state = JITTER;
+			/* In End of Conversion interrupt mode, the AD714X
+			 * continuously generates hardware interrupts.
+			 */
+			ad714x_wheel_use_com_int(ad714x, idx);
+			dev_dbg(ad714x->dev, "wheel %d touched\n", idx);
+		}
+		break;
+
+	case JITTER:
+		if (c_state == mask)	{
+			ad714x_wheel_cal_sensor_val(ad714x, idx);
+			ad714x_wheel_cal_highest_stage(ad714x, idx);
+			ad714x_wheel_cal_abs_pos(ad714x, idx);
+			sw->flt_pos = sw->abs_pos;
+			sw->state = ACTIVE;
+		}
+		break;
+
+	case ACTIVE:
+		if (c_state == mask) {
+			if (h_state) {
+				ad714x_wheel_cal_sensor_val(ad714x, idx);
+				ad714x_wheel_cal_highest_stage(ad714x, idx);
+				ad714x_wheel_cal_abs_pos(ad714x, idx);
+				ad714x_wheel_cal_flt_pos(ad714x, idx);
+
+				input_report_abs(sw->input, ABS_WHEEL,
+					sw->abs_pos);
+				input_report_key(sw->input, BTN_TOUCH, 1);
+			} else {
+				/* When the user lifts off the sensor, configure
+				 * the AD714X back to threshold interrupt mode.
+				 */
+				ad714x_wheel_use_thr_int(ad714x, idx);
+				sw->state = IDLE;
+				input_report_key(sw->input, BTN_TOUCH, 0);
+
+				dev_dbg(ad714x->dev, "wheel %d released\n",
+					idx);
+			}
+			input_sync(sw->input);
+		}
+		break;
+
+	default:
+		break;
+	}
+}
+
+static void touchpad_cal_sensor_val(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	int i;
+
+	for (i = hw->x_start_stage; i <= hw->x_end_stage; i++) {
+		ad714x->read(ad714x->dev, CDC_RESULT_S0 + i,
+				&ad714x->adc_reg[i]);
+		ad714x->read(ad714x->dev,
+				STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
+				&ad714x->amb_reg[i]);
+		if (ad714x->adc_reg[i] > ad714x->amb_reg[i])
+			ad714x->sensor_val[i] = ad714x->adc_reg[i] -
+				ad714x->amb_reg[i];
+		else
+			ad714x->sensor_val[i] = 0;
+	}
+}
+
+static void touchpad_cal_highest_stage(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	struct ad714x_touchpad_drv *sw = &ad714x->sw->touchpad[idx];
+
+	sw->x_highest_stage = ad714x_cal_highest_stage(ad714x,
+		hw->x_start_stage, hw->x_end_stage);
+	sw->y_highest_stage = ad714x_cal_highest_stage(ad714x,
+		hw->y_start_stage, hw->y_end_stage);
+
+	dev_dbg(ad714x->dev,
+		"touchpad %d x_highest_stage:%d, y_highest_stage:%d\n",
+		idx, sw->x_highest_stage, sw->y_highest_stage);
+}
+
+/*
+ * If 2 fingers are touching the sensor then 2 peaks can be observed in the
+ * distribution.
+ * The arithmetic doesn't support to get absolute coordinates for multi-touch
+ * yet.
+ */
+static int touchpad_check_second_peak(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	struct ad714x_touchpad_drv *sw = &ad714x->sw->touchpad[idx];
+	int i;
+
+	for (i = hw->x_start_stage; i < sw->x_highest_stage; i++) {
+		if ((ad714x->sensor_val[i] - ad714x->sensor_val[i + 1])
+			> (ad714x->sensor_val[i + 1] / 10))
+			return 1;
+	}
+
+	for (i = sw->x_highest_stage; i < hw->x_end_stage; i++) {
+		if ((ad714x->sensor_val[i + 1] - ad714x->sensor_val[i])
+			> (ad714x->sensor_val[i] / 10))
+			return 1;
+	}
+
+	for (i = hw->y_start_stage; i < sw->y_highest_stage; i++) {
+		if ((ad714x->sensor_val[i] - ad714x->sensor_val[i + 1])
+			> (ad714x->sensor_val[i + 1] / 10))
+			return 1;
+	}
+
+	for (i = sw->y_highest_stage; i < hw->y_end_stage; i++) {
+		if ((ad714x->sensor_val[i + 1] - ad714x->sensor_val[i])
+			> (ad714x->sensor_val[i] / 10))
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * If only one finger is used to activate the touch pad then only 1 peak will be
+ * registered in the distribution. This peak and the 2 adjacent sensors will be
+ * used in the calculation of the absolute position. This will prevent hand
+ * shadows to affect the absolute position calculation.
+ */
+static void touchpad_cal_abs_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	struct ad714x_touchpad_drv *sw = &ad714x->sw->touchpad[idx];
+
+	sw->x_abs_pos = ad714x_cal_abs_pos(ad714x, hw->x_start_stage,
+			hw->x_end_stage, sw->x_highest_stage, hw->x_max_coord);
+	sw->y_abs_pos = ad714x_cal_abs_pos(ad714x, hw->y_start_stage,
+			hw->y_end_stage, sw->y_highest_stage, hw->y_max_coord);
+
+	dev_dbg(ad714x->dev, "touchpad %d absolute position:(%d, %d)\n", idx,
+			sw->x_abs_pos, sw->y_abs_pos);
+}
+
+static void touchpad_cal_flt_pos(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_drv *sw = &ad714x->sw->touchpad[idx];
+
+	sw->x_flt_pos = (sw->x_flt_pos * (10 - 4) +
+			sw->x_abs_pos * 4)/10;
+	sw->y_flt_pos = (sw->y_flt_pos * (10 - 4) +
+			sw->y_abs_pos * 4)/10;
+
+	dev_dbg(ad714x->dev, "touchpad %d filter position:(%d, %d)\n",
+			idx, sw->x_flt_pos, sw->y_flt_pos);
+}
+
+/*
+ * To prevent distortion from showing in the absolute position, it is
+ * necessary to detect the end points. When endpoints are detected, the
+ * driver stops updating the status variables with absolute positions.
+ * End points are detected on the 4 edges of the touchpad sensor. The
+ * method to detect them is the same for all 4.
+ * To detect the end points, the firmware computes the difference in
+ * percent between the sensor on the edge and the adjacent one. The
+ * difference is calculated in percent in order to make the end point
+ * detection independent of the pressure.
+ */
+
+#define LEFT_END_POINT_DETECTION_LEVEL                  550
+#define RIGHT_END_POINT_DETECTION_LEVEL                 750
+#define LEFT_RIGHT_END_POINT_DEAVTIVALION_LEVEL         850
+#define TOP_END_POINT_DETECTION_LEVEL                   550
+#define BOTTOM_END_POINT_DETECTION_LEVEL                950
+#define TOP_BOTTOM_END_POINT_DEAVTIVALION_LEVEL         700
+static int touchpad_check_endpoint(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	struct ad714x_touchpad_drv *sw  = &ad714x->sw->touchpad[idx];
+	int percent_sensor_diff;
+
+	/* left endpoint detect */
+	percent_sensor_diff = (ad714x->sensor_val[hw->x_start_stage] -
+			ad714x->sensor_val[hw->x_start_stage + 1]) * 100 /
+			ad714x->sensor_val[hw->x_start_stage + 1];
+	if (!sw->left_ep) {
+		if (percent_sensor_diff >= LEFT_END_POINT_DETECTION_LEVEL)  {
+			sw->left_ep = 1;
+			sw->left_ep_val =
+				ad714x->sensor_val[hw->x_start_stage + 1];
+		}
+	} else {
+		if ((percent_sensor_diff < LEFT_END_POINT_DETECTION_LEVEL) &&
+		    (ad714x->sensor_val[hw->x_start_stage + 1] >
+		     LEFT_RIGHT_END_POINT_DEAVTIVALION_LEVEL + sw->left_ep_val))
+			sw->left_ep = 0;
+	}
+
+	/* right endpoint detect */
+	percent_sensor_diff = (ad714x->sensor_val[hw->x_end_stage] -
+			ad714x->sensor_val[hw->x_end_stage - 1]) * 100 /
+			ad714x->sensor_val[hw->x_end_stage - 1];
+	if (!sw->right_ep) {
+		if (percent_sensor_diff >= RIGHT_END_POINT_DETECTION_LEVEL)  {
+			sw->right_ep = 1;
+			sw->right_ep_val =
+				ad714x->sensor_val[hw->x_end_stage - 1];
+		}
+	} else {
+		if ((percent_sensor_diff < RIGHT_END_POINT_DETECTION_LEVEL) &&
+		(ad714x->sensor_val[hw->x_end_stage - 1] >
+		LEFT_RIGHT_END_POINT_DEAVTIVALION_LEVEL + sw->right_ep_val))
+			sw->right_ep = 0;
+	}
+
+	/* top endpoint detect */
+	percent_sensor_diff = (ad714x->sensor_val[hw->y_start_stage] -
+			ad714x->sensor_val[hw->y_start_stage + 1]) * 100 /
+			ad714x->sensor_val[hw->y_start_stage + 1];
+	if (!sw->top_ep) {
+		if (percent_sensor_diff >= TOP_END_POINT_DETECTION_LEVEL)  {
+			sw->top_ep = 1;
+			sw->top_ep_val =
+				ad714x->sensor_val[hw->y_start_stage + 1];
+		}
+	} else {
+		if ((percent_sensor_diff < TOP_END_POINT_DETECTION_LEVEL) &&
+		(ad714x->sensor_val[hw->y_start_stage + 1] >
+		TOP_BOTTOM_END_POINT_DEAVTIVALION_LEVEL + sw->top_ep_val))
+			sw->top_ep = 0;
+	}
+
+	/* bottom endpoint detect */
+	percent_sensor_diff = (ad714x->sensor_val[hw->y_end_stage] -
+		ad714x->sensor_val[hw->y_end_stage - 1]) * 100 /
+		ad714x->sensor_val[hw->y_end_stage - 1];
+	if (!sw->bottom_ep) {
+		if (percent_sensor_diff >= BOTTOM_END_POINT_DETECTION_LEVEL)  {
+			sw->bottom_ep = 1;
+			sw->bottom_ep_val =
+				ad714x->sensor_val[hw->y_end_stage - 1];
+		}
+	} else {
+		if ((percent_sensor_diff < BOTTOM_END_POINT_DETECTION_LEVEL) &&
+		(ad714x->sensor_val[hw->y_end_stage - 1] >
+		 TOP_BOTTOM_END_POINT_DEAVTIVALION_LEVEL + sw->bottom_ep_val))
+			sw->bottom_ep = 0;
+	}
+
+	return sw->left_ep || sw->right_ep || sw->top_ep || sw->bottom_ep;
+}
+
+static void touchpad_use_com_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+
+	ad714x_use_com_int(ad714x, hw->x_start_stage, hw->x_end_stage);
+}
+
+static void touchpad_use_thr_int(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+
+	ad714x_use_thr_int(ad714x, hw->x_start_stage, hw->x_end_stage);
+	ad714x_use_thr_int(ad714x, hw->y_start_stage, hw->y_end_stage);
+}
+
+static void ad714x_touchpad_state_machine(struct ad714x_chip *ad714x, int idx)
+{
+	struct ad714x_touchpad_plat *hw = &ad714x->hw->touchpad[idx];
+	struct ad714x_touchpad_drv *sw = &ad714x->sw->touchpad[idx];
+	unsigned short h_state, c_state;
+	unsigned short mask;
+
+	mask = (((1 << (hw->x_end_stage + 1)) - 1) -
+		((1 << hw->x_start_stage) - 1)) +
+		(((1 << (hw->y_end_stage + 1)) - 1) -
+		((1 << hw->y_start_stage) - 1));
+
+	h_state = ad714x->h_state & mask;
+	c_state = ad714x->c_state & mask;
+
+	switch (sw->state) {
+	case IDLE:
+		if (h_state) {
+			sw->state = JITTER;
+			/* In End of Conversion interrupt mode, the AD714X
+			 * continuously generates hardware interrupts.
+			 */
+			touchpad_use_com_int(ad714x, idx);
+			dev_dbg(ad714x->dev, "touchpad %d touched\n", idx);
+		}
+		break;
+
+	case JITTER:
+		if (c_state == mask) {
+			touchpad_cal_sensor_val(ad714x, idx);
+			touchpad_cal_highest_stage(ad714x, idx);
+			if ((!touchpad_check_second_peak(ad714x, idx)) &&
+				(!touchpad_check_endpoint(ad714x, idx))) {
+				dev_dbg(ad714x->dev,
+					"touchpad%d, 2 fingers or endpoint\n",
+					idx);
+				touchpad_cal_abs_pos(ad714x, idx);
+				sw->x_flt_pos = sw->x_abs_pos;
+				sw->y_flt_pos = sw->y_abs_pos;
+				sw->state = ACTIVE;
+			}
+		}
+		break;
+
+	case ACTIVE:
+		if (c_state == mask) {
+			if (h_state) {
+				touchpad_cal_sensor_val(ad714x, idx);
+				touchpad_cal_highest_stage(ad714x, idx);
+				if ((!touchpad_check_second_peak(ad714x, idx))
+				  && (!touchpad_check_endpoint(ad714x, idx))) {
+					touchpad_cal_abs_pos(ad714x, idx);
+					touchpad_cal_flt_pos(ad714x, idx);
+					input_report_abs(sw->input, ABS_X,
+						sw->x_flt_pos);
+					input_report_abs(sw->input, ABS_Y,
+						sw->y_flt_pos);
+					input_report_key(sw->input, BTN_TOUCH,
+						1);
+				}
+			} else {
+				/* When the user lifts off the sensor, configure
+				 * the AD714X back to threshold interrupt mode.
+				 */
+				touchpad_use_thr_int(ad714x, idx);
+				sw->state = IDLE;
+				input_report_key(sw->input, BTN_TOUCH, 0);
+				dev_dbg(ad714x->dev, "touchpad %d released\n",
+					idx);
+			}
+			input_sync(sw->input);
+		}
+		break;
+
+	default:
+		break;
+	}
+}
+
+static int ad714x_hw_detect(struct ad714x_chip *ad714x)
+{
+	unsigned short data;
+
+	ad714x->read(ad714x->dev, AD714X_PARTID_REG, &data);
+	switch (data & 0xFFF0) {
+	case AD7147_PARTID:
+		ad714x->product = 0x7147;
+		ad714x->version = data & 0xF;
+		dev_info(ad714x->dev, "found AD7147 captouch, rev:%d\n",
+				ad714x->version);
+		return 0;
+
+	case AD7142_PARTID:
+		ad714x->product = 0x7142;
+		ad714x->version = data & 0xF;
+		dev_info(ad714x->dev, "found AD7142 captouch, rev:%d\n",
+				ad714x->version);
+		return 0;
+
+	default:
+		dev_err(ad714x->dev,
+			"fail to detect AD714X captouch, read ID is %04x\n",
+			data);
+		return -ENODEV;
+	}
+}
+
+static void ad714x_hw_init(struct ad714x_chip *ad714x)
+{
+	int i, j;
+	unsigned short reg_base;
+	unsigned short data;
+
+	/* configuration CDC and interrupts */
+
+	for (i = 0; i < STAGE_NUM; i++) {
+		reg_base = AD714X_STAGECFG_REG + i * STAGE_CFGREG_NUM;
+		for (j = 0; j < STAGE_CFGREG_NUM; j++)
+			ad714x->write(ad714x->dev, reg_base + j,
+					ad714x->hw->stage_cfg_reg[i][j]);
+	}
+
+	for (i = 0; i < SYS_CFGREG_NUM; i++)
+		ad714x->write(ad714x->dev, AD714X_SYSCFG_REG + i,
+			ad714x->hw->sys_cfg_reg[i]);
+	for (i = 0; i < SYS_CFGREG_NUM; i++)
+		ad714x->read(ad714x->dev, AD714X_SYSCFG_REG + i,
+			&data);
+
+	ad714x->write(ad714x->dev, AD714X_STG_CAL_EN_REG, 0xFFF);
+
+	/* clear all interrupts */
+	ad714x->read(ad714x->dev, STG_LOW_INT_STA_REG, &data);
+	ad714x->read(ad714x->dev, STG_HIGH_INT_STA_REG, &data);
+	ad714x->read(ad714x->dev, STG_COM_INT_STA_REG, &data);
+}
+
+static irqreturn_t ad714x_interrupt_thread(int irq, void *data)
+{
+	struct ad714x_chip *ad714x = data;
+	int i;
+
+	mutex_lock(&ad714x->mutex);
+
+	ad714x->read(ad714x->dev, STG_LOW_INT_STA_REG, &ad714x->l_state);
+	ad714x->read(ad714x->dev, STG_HIGH_INT_STA_REG, &ad714x->h_state);
+	ad714x->read(ad714x->dev, STG_COM_INT_STA_REG, &ad714x->c_state);
+
+	for (i = 0; i < ad714x->hw->button_num; i++)
+		ad714x_button_state_machine(ad714x, i);
+	for (i = 0; i < ad714x->hw->slider_num; i++)
+		ad714x_slider_state_machine(ad714x, i);
+	for (i = 0; i < ad714x->hw->wheel_num; i++)
+		ad714x_wheel_state_machine(ad714x, i);
+	for (i = 0; i < ad714x->hw->touchpad_num; i++)
+		ad714x_touchpad_state_machine(ad714x, i);
+
+	mutex_unlock(&ad714x->mutex);
+
+	return IRQ_HANDLED;
+}
+
+#define MAX_DEVICE_NUM 8
+struct ad714x_chip *ad714x_probe(struct device *dev, u16 bus_type, int irq,
+				 ad714x_read_t read, ad714x_write_t write)
+{
+	int i, alloc_idx;
+	int error;
+	struct input_dev *input[MAX_DEVICE_NUM];
+
+	struct ad714x_platform_data *plat_data = dev->platform_data;
+	struct ad714x_chip *ad714x;
+	void *drv_mem;
+
+	struct ad714x_button_drv *bt_drv;
+	struct ad714x_slider_drv *sd_drv;
+	struct ad714x_wheel_drv *wl_drv;
+	struct ad714x_touchpad_drv *tp_drv;
+
+
+	if (irq <= 0) {
+		dev_err(dev, "IRQ not configured!\n");
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	if (dev->platform_data == NULL) {
+		dev_err(dev, "platform data for ad714x doesn't exist\n");
+		error = -EINVAL;
+		goto err_out;
+	}
+
+	ad714x = kzalloc(sizeof(*ad714x) + sizeof(*ad714x->sw) +
+			 sizeof(*sd_drv) * plat_data->slider_num +
+			 sizeof(*wl_drv) * plat_data->wheel_num +
+			 sizeof(*tp_drv) * plat_data->touchpad_num +
+			 sizeof(*bt_drv) * plat_data->button_num, GFP_KERNEL);
+	if (!ad714x) {
+		error = -ENOMEM;
+		goto err_out;
+	}
+
+	ad714x->hw = plat_data;
+
+	drv_mem = ad714x + 1;
+	ad714x->sw = drv_mem;
+	drv_mem += sizeof(*ad714x->sw);
+	ad714x->sw->slider = sd_drv = drv_mem;
+	drv_mem += sizeof(*sd_drv) * ad714x->hw->slider_num;
+	ad714x->sw->wheel = wl_drv = drv_mem;
+	drv_mem += sizeof(*wl_drv) * ad714x->hw->wheel_num;
+	ad714x->sw->touchpad = tp_drv = drv_mem;
+	drv_mem += sizeof(*tp_drv) * ad714x->hw->touchpad_num;
+	ad714x->sw->button = bt_drv = drv_mem;
+	drv_mem += sizeof(*bt_drv) * ad714x->hw->button_num;
+
+	ad714x->read = read;
+	ad714x->write = write;
+	ad714x->irq = irq;
+	ad714x->dev = dev;
+
+	error = ad714x_hw_detect(ad714x);
+	if (error)
+		goto err_free_mem;
+
+	/* initilize and request sw/hw resources */
+
+	ad714x_hw_init(ad714x);
+	mutex_init(&ad714x->mutex);
+
+	/*
+	 * Allocate and register AD714X input device
+	 */
+	alloc_idx = 0;
+
+	/* a slider uses one input_dev instance */
+	if (ad714x->hw->slider_num > 0) {
+		struct ad714x_slider_plat *sd_plat = ad714x->hw->slider;
+
+		for (i = 0; i < ad714x->hw->slider_num; i++) {
+			sd_drv[i].input = input[alloc_idx] = input_allocate_device();
+			if (!input[alloc_idx]) {
+				error = -ENOMEM;
+				goto err_free_dev;
+			}
+
+			__set_bit(EV_ABS, input[alloc_idx]->evbit);
+			__set_bit(EV_KEY, input[alloc_idx]->evbit);
+			__set_bit(ABS_X, input[alloc_idx]->absbit);
+			__set_bit(BTN_TOUCH, input[alloc_idx]->keybit);
+			input_set_abs_params(input[alloc_idx],
+				ABS_X, 0, sd_plat->max_coord, 0, 0);
+
+			input[alloc_idx]->id.bustype = bus_type;
+			input[alloc_idx]->id.product = ad714x->product;
+			input[alloc_idx]->id.version = ad714x->version;
+
+			error = input_register_device(input[alloc_idx]);
+			if (error)
+				goto err_free_dev;
+
+			alloc_idx++;
+		}
+	}
+
+	/* a wheel uses one input_dev instance */
+	if (ad714x->hw->wheel_num > 0) {
+		struct ad714x_wheel_plat *wl_plat = ad714x->hw->wheel;
+
+		for (i = 0; i < ad714x->hw->wheel_num; i++) {
+			wl_drv[i].input = input[alloc_idx] = input_allocate_device();
+			if (!input[alloc_idx]) {
+				error = -ENOMEM;
+				goto err_free_dev;
+			}
+
+			__set_bit(EV_KEY, input[alloc_idx]->evbit);
+			__set_bit(EV_ABS, input[alloc_idx]->evbit);
+			__set_bit(ABS_WHEEL, input[alloc_idx]->absbit);
+			__set_bit(BTN_TOUCH, input[alloc_idx]->keybit);
+			input_set_abs_params(input[alloc_idx],
+				ABS_WHEEL, 0, wl_plat->max_coord, 0, 0);
+
+			input[alloc_idx]->id.bustype = bus_type;
+			input[alloc_idx]->id.product = ad714x->product;
+			input[alloc_idx]->id.version = ad714x->version;
+
+			error = input_register_device(input[alloc_idx]);
+			if (error)
+				goto err_free_dev;
+
+			alloc_idx++;
+		}
+	}
+
+	/* a touchpad uses one input_dev instance */
+	if (ad714x->hw->touchpad_num > 0) {
+		struct ad714x_touchpad_plat *tp_plat = ad714x->hw->touchpad;
+
+		for (i = 0; i < ad714x->hw->touchpad_num; i++) {
+			tp_drv[i].input = input[alloc_idx] = input_allocate_device();
+			if (!input[alloc_idx]) {
+				error = -ENOMEM;
+				goto err_free_dev;
+			}
+
+			__set_bit(EV_ABS, input[alloc_idx]->evbit);
+			__set_bit(EV_KEY, input[alloc_idx]->evbit);
+			__set_bit(ABS_X, input[alloc_idx]->absbit);
+			__set_bit(ABS_Y, input[alloc_idx]->absbit);
+			__set_bit(BTN_TOUCH, input[alloc_idx]->keybit);
+			input_set_abs_params(input[alloc_idx],
+				ABS_X, 0, tp_plat->x_max_coord, 0, 0);
+			input_set_abs_params(input[alloc_idx],
+				ABS_Y, 0, tp_plat->y_max_coord, 0, 0);
+
+			input[alloc_idx]->id.bustype = bus_type;
+			input[alloc_idx]->id.product = ad714x->product;
+			input[alloc_idx]->id.version = ad714x->version;
+
+			error = input_register_device(input[alloc_idx]);
+			if (error)
+				goto err_free_dev;
+
+			alloc_idx++;
+		}
+	}
+
+	/* all buttons use one input node */
+	if (ad714x->hw->button_num > 0) {
+		struct ad714x_button_plat *bt_plat = ad714x->hw->button;
+
+		input[alloc_idx] = input_allocate_device();
+		if (!input[alloc_idx]) {
+			error = -ENOMEM;
+			goto err_free_dev;
+		}
+
+		__set_bit(EV_KEY, input[alloc_idx]->evbit);
+		for (i = 0; i < ad714x->hw->button_num; i++) {
+			bt_drv[i].input = input[alloc_idx];
+			__set_bit(bt_plat[i].keycode, input[alloc_idx]->keybit);
+		}
+
+		input[alloc_idx]->id.bustype = bus_type;
+		input[alloc_idx]->id.product = ad714x->product;
+		input[alloc_idx]->id.version = ad714x->version;
+
+		error = input_register_device(input[alloc_idx]);
+		if (error)
+			goto err_free_dev;
+
+		alloc_idx++;
+	}
+
+	error = request_threaded_irq(ad714x->irq, NULL, ad714x_interrupt_thread,
+			IRQF_TRIGGER_FALLING, "ad714x_captouch", ad714x);
+	if (error) {
+		dev_err(dev, "can't allocate irq %d\n", ad714x->irq);
+		goto err_unreg_dev;
+	}
+
+	return ad714x;
+
+ err_free_dev:
+	dev_err(dev, "failed to setup AD714x input device %i\n", alloc_idx);
+	input_free_device(input[alloc_idx]);
+ err_unreg_dev:
+	while (--alloc_idx >= 0)
+		input_unregister_device(input[alloc_idx]);
+ err_free_mem:
+	kfree(ad714x);
+ err_out:
+	return ERR_PTR(error);
+}
+EXPORT_SYMBOL(ad714x_probe);
+
+void ad714x_remove(struct ad714x_chip *ad714x)
+{
+	struct ad714x_platform_data *hw = ad714x->hw;
+	struct ad714x_driver_data *sw = ad714x->sw;
+	int i;
+
+	free_irq(ad714x->irq, ad714x);
+
+	/* unregister and free all input devices */
+
+	for (i = 0; i < hw->slider_num; i++)
+		input_unregister_device(sw->slider[i].input);
+
+	for (i = 0; i < hw->wheel_num; i++)
+		input_unregister_device(sw->wheel[i].input);
+
+	for (i = 0; i < hw->touchpad_num; i++)
+		input_unregister_device(sw->touchpad[i].input);
+
+	if (hw->button_num)
+		input_unregister_device(sw->button[0].input);
+
+	kfree(ad714x);
+}
+EXPORT_SYMBOL(ad714x_remove);
+
+#ifdef CONFIG_PM
+int ad714x_disable(struct ad714x_chip *ad714x)
+{
+	unsigned short data;
+
+	dev_dbg(ad714x->dev, "%s enter\n", __func__);
+
+	mutex_lock(&ad714x->mutex);
+
+	data = ad714x->hw->sys_cfg_reg[AD714X_PWR_CTRL] | 0x3;
+	ad714x->write(ad714x->dev, AD714X_PWR_CTRL, data);
+
+	mutex_unlock(&ad714x->mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL(ad714x_disable);
+
+int ad714x_enable(struct ad714x_chip *ad714x)
+{
+	unsigned short data;
+
+	dev_dbg(ad714x->dev, "%s enter\n", __func__);
+
+	mutex_lock(&ad714x->mutex);
+
+	/* resume to non-shutdown mode */
+
+	ad714x->write(ad714x->dev, AD714X_PWR_CTRL,
+			ad714x->hw->sys_cfg_reg[AD714X_PWR_CTRL]);
+
+	/* make sure the interrupt output line is not low level after resume,
+	 * otherwise we will get no chance to enter falling-edge irq again
+	 */
+
+	ad714x->read(ad714x->dev, STG_LOW_INT_STA_REG, &data);
+	ad714x->read(ad714x->dev, STG_HIGH_INT_STA_REG, &data);
+	ad714x->read(ad714x->dev, STG_COM_INT_STA_REG, &data);
+
+	mutex_unlock(&ad714x->mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL(ad714x_enable);
+#endif
+
+MODULE_DESCRIPTION("Analog Devices AD714X Capacitance Touch Sensor Driver");
+MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
+MODULE_LICENSE("GPL");