// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * AD714X CapTouch Programmable Controller driver supporting AD7142/3/7/8/7A
 *
 * Copyright 2009-2011 Analog Devices Inc.
 */

#include <linux/device.h>
#include <linux/export.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/input/ad714x.h>
#include <linux/module.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 AD7142_PARTID             0xE620
#define AD7143_PARTID             0xE630
#define AD7147_PARTID             0x1470
#define AD7148_PARTID             0x1480
#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_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_highest_stage;
        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
 */

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) - 1);

        ad714x->read(ad714x, STG_COM_INT_EN_REG, &data, 1);
        data |= 1 << end_stage;
        ad714x->write(ad714x, STG_COM_INT_EN_REG, data);

        ad714x->read(ad714x, STG_HIGH_INT_EN_REG, &data, 1);
        data &= ~mask;
        ad714x->write(ad714x, 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) - 1);

        ad714x->read(ad714x, STG_COM_INT_EN_REG, &data, 1);
        data &= ~(1 << end_stage);
        ad714x->write(ad714x, STG_COM_INT_EN_REG, data);

        ad714x->read(ad714x, STG_HIGH_INT_EN_REG, &data, 1);
        data |= mask;
        ad714x->write(ad714x, 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;

        ad714x->read(ad714x, CDC_RESULT_S0 + hw->start_stage,
                        &ad714x->adc_reg[hw->start_stage],
                        hw->end_stage - hw->start_stage + 1);

        for (i = hw->start_stage; i <= hw->end_stage; i++) {
                ad714x->read(ad714x, STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
                                &ad714x->amb_reg[i], 1);

                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;

        ad714x->read(ad714x, CDC_RESULT_S0 + hw->start_stage,
                        &ad714x->adc_reg[hw->start_stage],
                        hw->end_stage - hw->start_stage + 1);

        for (i = hw->start_stage; i <= hw->end_stage; i++) {
                ad714x->read(ad714x, STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
                                &ad714x->amb_reg[i], 1);
                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 sensors that constitutes
 * the scrollwheel. Then we determined the 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.
 */

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 first_before, highest, first_after;
        int a_param, b_param;

        first_before = (sw->highest_stage + stage_num - 1) % stage_num;
        highest = sw->highest_stage;
        first_after = (sw->highest_stage + stage_num + 1) % stage_num;

        a_param = ad714x->sensor_val[highest] *
                (highest - hw->start_stage) +
                ad714x->sensor_val[first_before] *
                (highest - hw->start_stage - 1) +
                ad714x->sensor_val[first_after] *
                (highest - hw->start_stage + 1);
        b_param = ad714x->sensor_val[highest] +
                ad714x->sensor_val[first_before] +
                ad714x->sensor_val[first_after];

        sw->abs_pos = ((hw->max_coord / (hw->end_stage - hw->start_stage)) *
                        a_param) / b_param;

        if (sw->abs_pos > hw->max_coord)
                sw->abs_pos = hw->max_coord;
        else if (sw->abs_pos < 0)
                sw->abs_pos = 0;
}

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->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_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;

        ad714x->read(ad714x, CDC_RESULT_S0 + hw->x_start_stage,
                        &ad714x->adc_reg[hw->x_start_stage],
                        hw->x_end_stage - hw->x_start_stage + 1);

        for (i = hw->x_start_stage; i <= hw->x_end_stage; i++) {
                ad714x->read(ad714x, STAGE0_AMBIENT + i * PER_STAGE_REG_NUM,
                                &ad714x->amb_reg[i], 1);
                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, AD714X_PARTID_REG, &data, 1);
        switch (data & 0xFFF0) {
        case AD7142_PARTID:
                ad714x->product = 0x7142;
                ad714x->version = data & 0xF;
                dev_info(ad714x->dev, "found AD7142 captouch, rev:%d\n",
                                ad714x->version);
                return 0;

        case AD7143_PARTID:
                ad714x->product = 0x7143;
                ad714x->version = data & 0xF;
                dev_info(ad714x->dev, "found AD7143 captouch, rev:%d\n",
                                ad714x->version);
                return 0;

        case AD7147_PARTID:
                ad714x->product = 0x7147;
                ad714x->version = data & 0xF;
                dev_info(ad714x->dev, "found AD7147(A) captouch, rev:%d\n",
                                ad714x->version);
                return 0;

        case AD7148_PARTID:
                ad714x->product = 0x7148;
                ad714x->version = data & 0xF;
                dev_info(ad714x->dev, "found AD7148 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, reg_base + j,
                                        ad714x->hw->stage_cfg_reg[i][j]);
        }

        for (i = 0; i < SYS_CFGREG_NUM; i++)
                ad714x->write(ad714x, AD714X_SYSCFG_REG + i,
                        ad714x->hw->sys_cfg_reg[i]);
        for (i = 0; i < SYS_CFGREG_NUM; i++)
                ad714x->read(ad714x, AD714X_SYSCFG_REG + i, &data, 1);

        ad714x->write(ad714x, AD714X_STG_CAL_EN_REG, 0xFFF);

        /* clear all interrupts */
        ad714x->read(ad714x, STG_LOW_INT_STA_REG, &ad714x->l_state, 3);
}

static irqreturn_t ad714x_interrupt_thread(int irq, void *data)
{
        struct ad714x_chip *ad714x = data;
        int i;

        guard(mutex)(&ad714x->mutex);

        ad714x->read(ad714x, STG_LOW_INT_STA_REG, &ad714x->l_state, 3);

        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);

        return IRQ_HANDLED;
}

struct ad714x_chip *ad714x_probe(struct device *dev, u16 bus_type, int irq,
                                 ad714x_read_t read, ad714x_write_t write)
{
        int i;
        int error;
        struct input_dev *input;

        struct ad714x_platform_data *plat_data = dev_get_platdata(dev);
        struct ad714x_chip *ad714x;
        void *drv_mem;
        unsigned long irqflags;

        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;
                return ERR_PTR(error);
        }

        if (dev_get_platdata(dev) == NULL) {
                dev_err(dev, "platform data for ad714x doesn't exist\n");
                error = -EINVAL;
                return ERR_PTR(error);
        }

        ad714x = devm_kzalloc(dev, 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;
                return ERR_PTR(error);
        }
        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)
                return ERR_PTR(error);

        /* initialize and request sw/hw resources */

        ad714x_hw_init(ad714x);
        mutex_init(&ad714x->mutex);

        /* 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++) {
                        input = devm_input_allocate_device(dev);
                        if (!input)
                                return ERR_PTR(-ENOMEM);

                        __set_bit(EV_ABS, input->evbit);
                        __set_bit(EV_KEY, input->evbit);
                        __set_bit(ABS_X, input->absbit);
                        __set_bit(BTN_TOUCH, input->keybit);
                        input_set_abs_params(input,
                                ABS_X, 0, sd_plat->max_coord, 0, 0);

                        input->id.bustype = bus_type;
                        input->id.product = ad714x->product;
                        input->id.version = ad714x->version;
                        input->name = "ad714x_captouch_slider";
                        input->dev.parent = dev;

                        error = input_register_device(input);
                        if (error)
                                return ERR_PTR(error);

                        sd_drv[i].input = input;
                }
        }

        /* 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++) {
                        input = devm_input_allocate_device(dev);
                        if (!input)
                                return ERR_PTR(-ENOMEM);

                        __set_bit(EV_KEY, input->evbit);
                        __set_bit(EV_ABS, input->evbit);
                        __set_bit(ABS_WHEEL, input->absbit);
                        __set_bit(BTN_TOUCH, input->keybit);
                        input_set_abs_params(input,
                                ABS_WHEEL, 0, wl_plat->max_coord, 0, 0);

                        input->id.bustype = bus_type;
                        input->id.product = ad714x->product;
                        input->id.version = ad714x->version;
                        input->name = "ad714x_captouch_wheel";
                        input->dev.parent = dev;

                        error = input_register_device(input);
                        if (error)
                                return ERR_PTR(error);

                        wl_drv[i].input = input;
                }
        }

        /* 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++) {
                        input = devm_input_allocate_device(dev);
                        if (!input)
                                return ERR_PTR(-ENOMEM);

                        __set_bit(EV_ABS, input->evbit);
                        __set_bit(EV_KEY, input->evbit);
                        __set_bit(ABS_X, input->absbit);
                        __set_bit(ABS_Y, input->absbit);
                        __set_bit(BTN_TOUCH, input->keybit);
                        input_set_abs_params(input,
                                ABS_X, 0, tp_plat->x_max_coord, 0, 0);
                        input_set_abs_params(input,
                                ABS_Y, 0, tp_plat->y_max_coord, 0, 0);

                        input->id.bustype = bus_type;
                        input->id.product = ad714x->product;
                        input->id.version = ad714x->version;
                        input->name = "ad714x_captouch_pad";
                        input->dev.parent = dev;

                        error = input_register_device(input);
                        if (error)
                                return ERR_PTR(error);

                        tp_drv[i].input = input;
                }
        }

        /* all buttons use one input node */
        if (ad714x->hw->button_num > 0) {
                struct ad714x_button_plat *bt_plat = ad714x->hw->button;

                input = devm_input_allocate_device(dev);
                if (!input) {
                        error = -ENOMEM;
                        return ERR_PTR(error);
                }

                __set_bit(EV_KEY, input->evbit);
                for (i = 0; i < ad714x->hw->button_num; i++) {
                        bt_drv[i].input = input;
                        __set_bit(bt_plat[i].keycode, input->keybit);
                }

                input->id.bustype = bus_type;
                input->id.product = ad714x->product;
                input->id.version = ad714x->version;
                input->name = "ad714x_captouch_button";
                input->dev.parent = dev;

                error = input_register_device(input);
                if (error)
                        return ERR_PTR(error);
        }

        irqflags = plat_data->irqflags ?: IRQF_TRIGGER_FALLING;
        irqflags |= IRQF_ONESHOT;

        error = devm_request_threaded_irq(dev, ad714x->irq, NULL,
                                          ad714x_interrupt_thread,
                                          irqflags, "ad714x_captouch", ad714x);
        if (error) {
                dev_err(dev, "can't allocate irq %d\n", ad714x->irq);
                return ERR_PTR(error);
        }

        return ad714x;
}
EXPORT_SYMBOL(ad714x_probe);

static int ad714x_suspend(struct device *dev)
{
        struct ad714x_chip *ad714x = dev_get_drvdata(dev);
        unsigned short data;

        dev_dbg(ad714x->dev, "%s enter\n", __func__);

        guard(mutex)(&ad714x->mutex);

        data = ad714x->hw->sys_cfg_reg[AD714X_PWR_CTRL] | 0x3;
        ad714x->write(ad714x, AD714X_PWR_CTRL, data);

        return 0;
}

static int ad714x_resume(struct device *dev)
{
        struct ad714x_chip *ad714x = dev_get_drvdata(dev);
        dev_dbg(ad714x->dev, "%s enter\n", __func__);

        guard(mutex)(&ad714x->mutex);

        /* resume to non-shutdown mode */

        ad714x->write(ad714x, 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, STG_LOW_INT_STA_REG, &ad714x->l_state, 3);

        return 0;
}

EXPORT_SIMPLE_DEV_PM_OPS(ad714x_pm, ad714x_suspend, ad714x_resume);

MODULE_DESCRIPTION("Analog Devices AD714X Capacitance Touch Sensor Driver");
MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_LICENSE("GPL");