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 * ROHM BU21023/24 Dual touch support resistive touch screen driver
 * Copyright (C) 2012 ROHM CO.,LTD.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 */
#include <linux/delay.h>
#include <linux/firmware.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/slab.h>

#define BU21023_NAME			"bu21023_ts"
#define BU21023_FIRMWARE_NAME		"bu21023.bin"

#define MAX_CONTACTS			2

#define AXIS_ADJUST			4
#define AXIS_OFFSET			8

#define FIRMWARE_BLOCK_SIZE		32U
#define FIRMWARE_RETRY_MAX		4

#define SAMPLING_DELAY			12	/* msec */

#define CALIBRATION_RETRY_MAX		6

#define ROHM_TS_ABS_X_MIN		40
#define ROHM_TS_ABS_X_MAX		990
#define ROHM_TS_ABS_Y_MIN		160
#define ROHM_TS_ABS_Y_MAX		920
#define ROHM_TS_DISPLACEMENT_MAX	0	/* zero for infinite */

/*
 * BU21023GUL/BU21023MUV/BU21024FV-M registers map
 */
#define VADOUT_YP_H		0x00
#define VADOUT_YP_L		0x01
#define VADOUT_XP_H		0x02
#define VADOUT_XP_L		0x03
#define VADOUT_YN_H		0x04
#define VADOUT_YN_L		0x05
#define VADOUT_XN_H		0x06
#define VADOUT_XN_L		0x07

#define PRM1_X_H		0x08
#define PRM1_X_L		0x09
#define PRM1_Y_H		0x0a
#define PRM1_Y_L		0x0b
#define PRM2_X_H		0x0c
#define PRM2_X_L		0x0d
#define PRM2_Y_H		0x0e
#define PRM2_Y_L		0x0f

#define MLT_PRM_MONI_X		0x10
#define MLT_PRM_MONI_Y		0x11

#define DEBUG_MONI_1		0x12
#define DEBUG_MONI_2		0x13

#define VADOUT_ZX_H		0x14
#define VADOUT_ZX_L		0x15
#define VADOUT_ZY_H		0x16
#define VADOUT_ZY_L		0x17

#define Z_PARAM_H		0x18
#define Z_PARAM_L		0x19

/*
 * Value for VADOUT_*_L
 */
#define VADOUT_L_MASK		0x01

/*
 * Value for PRM*_*_L
 */
#define PRM_L_MASK		0x01

#define POS_X1_H		0x20
#define POS_X1_L		0x21
#define POS_Y1_H		0x22
#define POS_Y1_L		0x23
#define POS_X2_H		0x24
#define POS_X2_L		0x25
#define POS_Y2_H		0x26
#define POS_Y2_L		0x27

/*
 * Value for POS_*_L
 */
#define POS_L_MASK		0x01

#define TOUCH			0x28
#define TOUCH_DETECT		0x01

#define TOUCH_GESTURE		0x29
#define SINGLE_TOUCH		0x01
#define DUAL_TOUCH		0x03
#define TOUCH_MASK		0x03
#define CALIBRATION_REQUEST	0x04
#define CALIBRATION_STATUS	0x08
#define CALIBRATION_MASK	0x0c
#define GESTURE_SPREAD		0x10
#define GESTURE_PINCH		0x20
#define GESTURE_ROTATE_R	0x40
#define GESTURE_ROTATE_L	0x80

#define INT_STATUS		0x2a
#define INT_MASK		0x3d
#define INT_CLEAR		0x3e

/*
 * Values for INT_*
 */
#define COORD_UPDATE		0x01
#define CALIBRATION_DONE	0x02
#define SLEEP_IN		0x04
#define SLEEP_OUT		0x08
#define PROGRAM_LOAD_DONE	0x10
#define ERROR			0x80
#define INT_ALL			0x9f

#define ERR_STATUS		0x2b
#define ERR_MASK		0x3f

/*
 * Values for ERR_*
 */
#define ADC_TIMEOUT		0x01
#define CPU_TIMEOUT		0x02
#define CALIBRATION_ERR		0x04
#define PROGRAM_LOAD_ERR	0x10

#define COMMON_SETUP1			0x30
#define PROGRAM_LOAD_HOST		0x02
#define PROGRAM_LOAD_EEPROM		0x03
#define CENSOR_4PORT			0x04
#define CENSOR_8PORT			0x00	/* Not supported by BU21023 */
#define CALIBRATION_TYPE_DEFAULT	0x08
#define CALIBRATION_TYPE_SPECIAL	0x00
#define INT_ACTIVE_HIGH			0x10
#define INT_ACTIVE_LOW			0x00
#define AUTO_CALIBRATION		0x40
#define MANUAL_CALIBRATION		0x00
#define COMMON_SETUP1_DEFAULT		0x4e

#define COMMON_SETUP2		0x31
#define MAF_NONE		0x00
#define MAF_1SAMPLE		0x01
#define MAF_3SAMPLES		0x02
#define MAF_5SAMPLES		0x03
#define INV_Y			0x04
#define INV_X			0x08
#define SWAP_XY			0x10

#define COMMON_SETUP3		0x32
#define EN_SLEEP		0x01
#define EN_MULTI		0x02
#define EN_GESTURE		0x04
#define EN_INTVL		0x08
#define SEL_STEP		0x10
#define SEL_MULTI		0x20
#define SEL_TBL_DEFAULT		0x40

#define INTERVAL_TIME		0x33
#define INTERVAL_TIME_DEFAULT	0x10

#define STEP_X			0x34
#define STEP_X_DEFAULT		0x41

#define STEP_Y			0x35
#define STEP_Y_DEFAULT		0x8d

#define OFFSET_X		0x38
#define OFFSET_X_DEFAULT	0x0c

#define OFFSET_Y		0x39
#define OFFSET_Y_DEFAULT	0x0c

#define THRESHOLD_TOUCH		0x3a
#define THRESHOLD_TOUCH_DEFAULT	0xa0

#define THRESHOLD_GESTURE		0x3b
#define THRESHOLD_GESTURE_DEFAULT	0x17

#define SYSTEM			0x40
#define ANALOG_POWER_ON		0x01
#define ANALOG_POWER_OFF	0x00
#define CPU_POWER_ON		0x02
#define CPU_POWER_OFF		0x00

#define FORCE_CALIBRATION	0x42
#define FORCE_CALIBRATION_ON	0x01
#define FORCE_CALIBRATION_OFF	0x00

#define CPU_FREQ		0x50	/* 10 / (reg + 1) MHz */
#define CPU_FREQ_10MHZ		0x00
#define CPU_FREQ_5MHZ		0x01
#define CPU_FREQ_1MHZ		0x09

#define EEPROM_ADDR		0x51

#define CALIBRATION_ADJUST		0x52
#define CALIBRATION_ADJUST_DEFAULT	0x00

#define THRESHOLD_SLEEP_IN	0x53

#define EVR_XY			0x56
#define EVR_XY_DEFAULT		0x10

#define PRM_SWOFF_TIME		0x57
#define PRM_SWOFF_TIME_DEFAULT	0x04

#define PROGRAM_VERSION		0x5f

#define ADC_CTRL		0x60
#define ADC_DIV_MASK		0x1f	/* The minimum value is 4 */
#define ADC_DIV_DEFAULT		0x08

#define ADC_WAIT		0x61
#define ADC_WAIT_DEFAULT	0x0a

#define SWCONT			0x62
#define SWCONT_DEFAULT		0x0f

#define EVR_X			0x63
#define EVR_X_DEFAULT		0x86

#define EVR_Y			0x64
#define EVR_Y_DEFAULT		0x64

#define TEST1			0x65
#define DUALTOUCH_STABILIZE_ON	0x01
#define DUALTOUCH_STABILIZE_OFF	0x00
#define DUALTOUCH_REG_ON	0x20
#define DUALTOUCH_REG_OFF	0x00

#define CALIBRATION_REG1		0x68
#define CALIBRATION_REG1_DEFAULT	0xd9

#define CALIBRATION_REG2		0x69
#define CALIBRATION_REG2_DEFAULT	0x36

#define CALIBRATION_REG3		0x6a
#define CALIBRATION_REG3_DEFAULT	0x32

#define EX_ADDR_H		0x70
#define EX_ADDR_L		0x71
#define EX_WDAT			0x72
#define EX_RDAT			0x73
#define EX_CHK_SUM1		0x74
#define EX_CHK_SUM2		0x75
#define EX_CHK_SUM3		0x76

struct rohm_ts_data {
	struct i2c_client *client;
	struct input_dev *input;

	bool initialized;

	unsigned int contact_count[MAX_CONTACTS + 1];
	int finger_count;

	u8 setup2;
};

/*
 * rohm_i2c_burst_read - execute combined I2C message for ROHM BU21023/24
 * @client: Handle to ROHM BU21023/24
 * @start: Where to start read address from ROHM BU21023/24
 * @buf: Where to store read data from ROHM BU21023/24
 * @len: How many bytes to read
 *
 * Returns negative errno, else zero on success.
 *
 * Note
 * In BU21023/24 burst read, stop condition is needed after "address write".
 * Therefore, transmission is performed in 2 steps.
 */
static int rohm_i2c_burst_read(struct i2c_client *client, u8 start, void *buf,
			       size_t len)
{
	struct i2c_adapter *adap = client->adapter;
	struct i2c_msg msg[2];
	int i, ret = 0;

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = 1;
	msg[0].buf = &start;

	msg[1].addr = client->addr;
	msg[1].flags = I2C_M_RD;
	msg[1].len = len;
	msg[1].buf = buf;

	i2c_lock_bus(adap, I2C_LOCK_SEGMENT);

	for (i = 0; i < 2; i++) {
		if (__i2c_transfer(adap, &msg[i], 1) < 0) {
			ret = -EIO;
			break;
		}
	}

	i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);

	return ret;
}

static int rohm_ts_manual_calibration(struct rohm_ts_data *ts)
{
	struct i2c_client *client = ts->client;
	struct device *dev = &client->dev;
	u8 buf[33];	/* for PRM1_X_H(0x08)-TOUCH(0x28) */

	int retry;
	bool success = false;
	bool first_time = true;
	bool calibration_done;

	u8 reg1, reg2, reg3;
	s32 reg1_orig, reg2_orig, reg3_orig;
	s32 val;

	int calib_x = 0, calib_y = 0;
	int reg_x, reg_y;
	int err_x, err_y;

	int error, error2;
	int i;

	reg1_orig = i2c_smbus_read_byte_data(client, CALIBRATION_REG1);
	if (reg1_orig < 0)
		return reg1_orig;

	reg2_orig = i2c_smbus_read_byte_data(client, CALIBRATION_REG2);
	if (reg2_orig < 0)
		return reg2_orig;

	reg3_orig = i2c_smbus_read_byte_data(client, CALIBRATION_REG3);
	if (reg3_orig < 0)
		return reg3_orig;

	error = i2c_smbus_write_byte_data(client, INT_MASK,
					  COORD_UPDATE | SLEEP_IN | SLEEP_OUT |
					  PROGRAM_LOAD_DONE);
	if (error)
		goto out;

	error = i2c_smbus_write_byte_data(client, TEST1,
					  DUALTOUCH_STABILIZE_ON);
	if (error)
		goto out;

	for (retry = 0; retry < CALIBRATION_RETRY_MAX; retry++) {
		/* wait 2 sampling for update */
		mdelay(2 * SAMPLING_DELAY);

#define READ_CALIB_BUF(reg)	buf[((reg) - PRM1_X_H)]

		error = rohm_i2c_burst_read(client, PRM1_X_H, buf, sizeof(buf));
		if (error)
			goto out;

		if (READ_CALIB_BUF(TOUCH) & TOUCH_DETECT)
			continue;

		if (first_time) {
			/* generate calibration parameter */
			calib_x = ((int)READ_CALIB_BUF(PRM1_X_H) << 2 |
				READ_CALIB_BUF(PRM1_X_L)) - AXIS_OFFSET;
			calib_y = ((int)READ_CALIB_BUF(PRM1_Y_H) << 2 |
				READ_CALIB_BUF(PRM1_Y_L)) - AXIS_OFFSET;

			error = i2c_smbus_write_byte_data(client, TEST1,
				DUALTOUCH_STABILIZE_ON | DUALTOUCH_REG_ON);
			if (error)
				goto out;

			first_time = false;
		} else {
			/* generate adjustment parameter */
			err_x = (int)READ_CALIB_BUF(PRM1_X_H) << 2 |
				READ_CALIB_BUF(PRM1_X_L);
			err_y = (int)READ_CALIB_BUF(PRM1_Y_H) << 2 |
				READ_CALIB_BUF(PRM1_Y_L);

			/* X axis ajust */
			if (err_x <= 4)
				calib_x -= AXIS_ADJUST;
			else if (err_x >= 60)
				calib_x += AXIS_ADJUST;

			/* Y axis ajust */
			if (err_y <= 4)
				calib_y -= AXIS_ADJUST;
			else if (err_y >= 60)
				calib_y += AXIS_ADJUST;
		}

		/* generate calibration setting value */
		reg_x = calib_x + ((calib_x & 0x200) << 1);
		reg_y = calib_y + ((calib_y & 0x200) << 1);

		/* convert for register format */
		reg1 = reg_x >> 3;
		reg2 = (reg_y & 0x7) << 4 | (reg_x & 0x7);
		reg3 = reg_y >> 3;

		error = i2c_smbus_write_byte_data(client,
						  CALIBRATION_REG1, reg1);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client,
						  CALIBRATION_REG2, reg2);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client,
						  CALIBRATION_REG3, reg3);
		if (error)
			goto out;

		/*
		 * force calibration sequcence
		 */
		error = i2c_smbus_write_byte_data(client, FORCE_CALIBRATION,
						  FORCE_CALIBRATION_OFF);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client, FORCE_CALIBRATION,
						  FORCE_CALIBRATION_ON);
		if (error)
			goto out;

		/* clear all interrupts */
		error = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);
		if (error)
			goto out;

		/*
		 * Wait for the status change of calibration, max 10 sampling
		 */
		calibration_done = false;

		for (i = 0; i < 10; i++) {
			mdelay(SAMPLING_DELAY);

			val = i2c_smbus_read_byte_data(client, TOUCH_GESTURE);
			if (!(val & CALIBRATION_MASK)) {
				calibration_done = true;
				break;
			} else if (val < 0) {
				error = val;
				goto out;
			}
		}

		if (calibration_done) {
			val = i2c_smbus_read_byte_data(client, INT_STATUS);
			if (val == CALIBRATION_DONE) {
				success = true;
				break;
			} else if (val < 0) {
				error = val;
				goto out;
			}
		} else {
			dev_warn(dev, "calibration timeout\n");
		}
	}

	if (!success) {
		error = i2c_smbus_write_byte_data(client, CALIBRATION_REG1,
						  reg1_orig);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client, CALIBRATION_REG2,
						  reg2_orig);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client, CALIBRATION_REG3,
						  reg3_orig);
		if (error)
			goto out;

		/* calibration data enable */
		error = i2c_smbus_write_byte_data(client, TEST1,
						  DUALTOUCH_STABILIZE_ON |
						  DUALTOUCH_REG_ON);
		if (error)
			goto out;

		/* wait 10 sampling */
		mdelay(10 * SAMPLING_DELAY);

		error = -EBUSY;
	}

out:
	error2 = i2c_smbus_write_byte_data(client, INT_MASK, INT_ALL);
	if (!error2)
		/* Clear all interrupts */
		error2 = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);

	return error ? error : error2;
}

static const unsigned int untouch_threshold[3] = { 0, 1, 5 };
static const unsigned int single_touch_threshold[3] = { 0, 0, 4 };
static const unsigned int dual_touch_threshold[3] = { 10, 8, 0 };

static irqreturn_t rohm_ts_soft_irq(int irq, void *dev_id)
{
	struct rohm_ts_data *ts = dev_id;
	struct i2c_client *client = ts->client;
	struct input_dev *input_dev = ts->input;
	struct device *dev = &client->dev;

	u8 buf[10];	/* for POS_X1_H(0x20)-TOUCH_GESTURE(0x29) */

	struct input_mt_pos pos[MAX_CONTACTS];
	int slots[MAX_CONTACTS];
	u8 touch_flags;
	unsigned int threshold;
	int finger_count = -1;
	int prev_finger_count = ts->finger_count;
	int count;
	int error;
	int i;

	error = i2c_smbus_write_byte_data(client, INT_MASK, INT_ALL);
	if (error)
		return IRQ_HANDLED;

	/* Clear all interrupts */
	error = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);
	if (error)
		return IRQ_HANDLED;

#define READ_POS_BUF(reg)	buf[((reg) - POS_X1_H)]

	error = rohm_i2c_burst_read(client, POS_X1_H, buf, sizeof(buf));
	if (error)
		return IRQ_HANDLED;

	touch_flags = READ_POS_BUF(TOUCH_GESTURE) & TOUCH_MASK;
	if (touch_flags) {
		/* generate coordinates */
		pos[0].x = ((s16)READ_POS_BUF(POS_X1_H) << 2) |
			   READ_POS_BUF(POS_X1_L);
		pos[0].y = ((s16)READ_POS_BUF(POS_Y1_H) << 2) |
			   READ_POS_BUF(POS_Y1_L);
		pos[1].x = ((s16)READ_POS_BUF(POS_X2_H) << 2) |
			   READ_POS_BUF(POS_X2_L);
		pos[1].y = ((s16)READ_POS_BUF(POS_Y2_H) << 2) |
			   READ_POS_BUF(POS_Y2_L);
	}

	switch (touch_flags) {
	case 0:
		threshold = untouch_threshold[prev_finger_count];
		if (++ts->contact_count[0] >= threshold)
			finger_count = 0;
		break;

	case SINGLE_TOUCH:
		threshold = single_touch_threshold[prev_finger_count];
		if (++ts->contact_count[1] >= threshold)
			finger_count = 1;

		if (finger_count == 1) {
			if (pos[1].x != 0 && pos[1].y != 0) {
				pos[0].x = pos[1].x;
				pos[0].y = pos[1].y;
				pos[1].x = 0;
				pos[1].y = 0;
			}
		}
		break;

	case DUAL_TOUCH:
		threshold = dual_touch_threshold[prev_finger_count];
		if (++ts->contact_count[2] >= threshold)
			finger_count = 2;
		break;

	default:
		dev_dbg(dev,
			"Three or more touches are not supported\n");
		return IRQ_HANDLED;
	}

	if (finger_count >= 0) {
		if (prev_finger_count != finger_count) {
			count = ts->contact_count[finger_count];
			memset(ts->contact_count, 0, sizeof(ts->contact_count));
			ts->contact_count[finger_count] = count;
		}

		input_mt_assign_slots(input_dev, slots, pos,
				      finger_count, ROHM_TS_DISPLACEMENT_MAX);

		for (i = 0; i < finger_count; i++) {
			input_mt_slot(input_dev, slots[i]);
			input_mt_report_slot_state(input_dev,
						   MT_TOOL_FINGER, true);
			input_report_abs(input_dev,
					 ABS_MT_POSITION_X, pos[i].x);
			input_report_abs(input_dev,
					 ABS_MT_POSITION_Y, pos[i].y);
		}

		input_mt_sync_frame(input_dev);
		input_mt_report_pointer_emulation(input_dev, true);
		input_sync(input_dev);

		ts->finger_count = finger_count;
	}

	if (READ_POS_BUF(TOUCH_GESTURE) & CALIBRATION_REQUEST) {
		error = rohm_ts_manual_calibration(ts);
		if (error)
			dev_warn(dev, "manual calibration failed: %d\n",
				 error);
	}

	i2c_smbus_write_byte_data(client, INT_MASK,
				  CALIBRATION_DONE | SLEEP_OUT | SLEEP_IN |
				  PROGRAM_LOAD_DONE);

	return IRQ_HANDLED;
}

static int rohm_ts_load_firmware(struct i2c_client *client,
				 const char *firmware_name)
{
	struct device *dev = &client->dev;
	const struct firmware *fw;
	s32 status;
	unsigned int offset, len, xfer_len;
	unsigned int retry = 0;
	int error, error2;

	error = request_firmware(&fw, firmware_name, dev);
	if (error) {
		dev_err(dev, "unable to retrieve firmware %s: %d\n",
			firmware_name, error);
		return error;
	}

	error = i2c_smbus_write_byte_data(client, INT_MASK,
					  COORD_UPDATE | CALIBRATION_DONE |
					  SLEEP_IN | SLEEP_OUT);
	if (error)
		goto out;

	do {
		if (retry) {
			dev_warn(dev, "retrying firmware load\n");

			/* settings for retry */
			error = i2c_smbus_write_byte_data(client, EX_WDAT, 0);
			if (error)
				goto out;
		}

		error = i2c_smbus_write_byte_data(client, EX_ADDR_H, 0);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client, EX_ADDR_L, 0);
		if (error)
			goto out;

		error = i2c_smbus_write_byte_data(client, COMMON_SETUP1,
						  COMMON_SETUP1_DEFAULT);
		if (error)
			goto out;

		/* firmware load to the device */
		offset = 0;
		len = fw->size;

		while (len) {
			xfer_len = min(FIRMWARE_BLOCK_SIZE, len);

			error = i2c_smbus_write_i2c_block_data(client, EX_WDAT,
						xfer_len, &fw->data[offset]);
			if (error)
				goto out;

			len -= xfer_len;
			offset += xfer_len;
		}

		/* check firmware load result */
		status = i2c_smbus_read_byte_data(client, INT_STATUS);
		if (status < 0) {
			error = status;
			goto out;
		}

		/* clear all interrupts */
		error = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);
		if (error)
			goto out;

		if (status == PROGRAM_LOAD_DONE)
			break;

		error = -EIO;
	} while (++retry <= FIRMWARE_RETRY_MAX);

out:
	error2 = i2c_smbus_write_byte_data(client, INT_MASK, INT_ALL);

	release_firmware(fw);

	return error ? error : error2;
}

static ssize_t swap_xy_show(struct device *dev, struct device_attribute *attr,
			    char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);

	return sprintf(buf, "%d\n", !!(ts->setup2 & SWAP_XY));
}

static ssize_t swap_xy_store(struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);
	unsigned int val;
	int error;

	error = kstrtouint(buf, 0, &val);
	if (error)
		return error;

	error = mutex_lock_interruptible(&ts->input->mutex);
	if (error)
		return error;

	if (val)
		ts->setup2 |= SWAP_XY;
	else
		ts->setup2 &= ~SWAP_XY;

	if (ts->initialized)
		error = i2c_smbus_write_byte_data(ts->client, COMMON_SETUP2,
						  ts->setup2);

	mutex_unlock(&ts->input->mutex);

	return error ? error : count;
}

static ssize_t inv_x_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);

	return sprintf(buf, "%d\n", !!(ts->setup2 & INV_X));
}

static ssize_t inv_x_store(struct device *dev, struct device_attribute *attr,
			   const char *buf, size_t count)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);
	unsigned int val;
	int error;

	error = kstrtouint(buf, 0, &val);
	if (error)
		return error;

	error = mutex_lock_interruptible(&ts->input->mutex);
	if (error)
		return error;

	if (val)
		ts->setup2 |= INV_X;
	else
		ts->setup2 &= ~INV_X;

	if (ts->initialized)
		error = i2c_smbus_write_byte_data(ts->client, COMMON_SETUP2,
						  ts->setup2);

	mutex_unlock(&ts->input->mutex);

	return error ? error : count;
}

static ssize_t inv_y_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);

	return sprintf(buf, "%d\n", !!(ts->setup2 & INV_Y));
}

static ssize_t inv_y_store(struct device *dev, struct device_attribute *attr,
			   const char *buf, size_t count)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rohm_ts_data *ts = i2c_get_clientdata(client);
	unsigned int val;
	int error;

	error = kstrtouint(buf, 0, &val);
	if (error)
		return error;

	error = mutex_lock_interruptible(&ts->input->mutex);
	if (error)
		return error;

	if (val)
		ts->setup2 |= INV_Y;
	else
		ts->setup2 &= ~INV_Y;

	if (ts->initialized)
		error = i2c_smbus_write_byte_data(client, COMMON_SETUP2,
						  ts->setup2);

	mutex_unlock(&ts->input->mutex);

	return error ? error : count;
}

static DEVICE_ATTR_RW(swap_xy);
static DEVICE_ATTR_RW(inv_x);
static DEVICE_ATTR_RW(inv_y);

static struct attribute *rohm_ts_attrs[] = {
	&dev_attr_swap_xy.attr,
	&dev_attr_inv_x.attr,
	&dev_attr_inv_y.attr,
	NULL,
};

static const struct attribute_group rohm_ts_attr_group = {
	.attrs = rohm_ts_attrs,
};

static int rohm_ts_device_init(struct i2c_client *client, u8 setup2)
{
	struct device *dev = &client->dev;
	int error;

	disable_irq(client->irq);

	/*
	 * Wait 200usec for reset
	 */
	udelay(200);

	/* Release analog reset */
	error = i2c_smbus_write_byte_data(client, SYSTEM,
					  ANALOG_POWER_ON | CPU_POWER_OFF);
	if (error)
		return error;

	/* Waiting for the analog warm-up, max. 200usec */
	udelay(200);

	/* clear all interrupts */
	error = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, EX_WDAT, 0);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, COMMON_SETUP1, 0);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, COMMON_SETUP2, setup2);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, COMMON_SETUP3,
					  SEL_TBL_DEFAULT | EN_MULTI);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, THRESHOLD_GESTURE,
					  THRESHOLD_GESTURE_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, INTERVAL_TIME,
					  INTERVAL_TIME_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, CPU_FREQ, CPU_FREQ_10MHZ);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, PRM_SWOFF_TIME,
					  PRM_SWOFF_TIME_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, ADC_CTRL, ADC_DIV_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, ADC_WAIT, ADC_WAIT_DEFAULT);
	if (error)
		return error;

	/*
	 * Panel setup, these values change with the panel.
	 */
	error = i2c_smbus_write_byte_data(client, STEP_X, STEP_X_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, STEP_Y, STEP_Y_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, OFFSET_X, OFFSET_X_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, OFFSET_Y, OFFSET_Y_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, THRESHOLD_TOUCH,
					  THRESHOLD_TOUCH_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, EVR_XY, EVR_XY_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, EVR_X, EVR_X_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, EVR_Y, EVR_Y_DEFAULT);
	if (error)
		return error;

	/* Fixed value settings */
	error = i2c_smbus_write_byte_data(client, CALIBRATION_ADJUST,
					  CALIBRATION_ADJUST_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, SWCONT, SWCONT_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, TEST1,
					  DUALTOUCH_STABILIZE_ON |
					  DUALTOUCH_REG_ON);
	if (error)
		return error;

	error = rohm_ts_load_firmware(client, BU21023_FIRMWARE_NAME);
	if (error) {
		dev_err(dev, "failed to load firmware: %d\n", error);
		return error;
	}

	/*
	 * Manual calibration results are not changed in same environment.
	 * If the force calibration is performed,
	 * the controller will not require calibration request interrupt
	 * when the typical values are set to the calibration registers.
	 */
	error = i2c_smbus_write_byte_data(client, CALIBRATION_REG1,
					  CALIBRATION_REG1_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, CALIBRATION_REG2,
					  CALIBRATION_REG2_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, CALIBRATION_REG3,
					  CALIBRATION_REG3_DEFAULT);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, FORCE_CALIBRATION,
					  FORCE_CALIBRATION_OFF);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, FORCE_CALIBRATION,
					  FORCE_CALIBRATION_ON);
	if (error)
		return error;

	/* Clear all interrupts */
	error = i2c_smbus_write_byte_data(client, INT_CLEAR, 0xff);
	if (error)
		return error;

	/* Enable coordinates update interrupt */
	error = i2c_smbus_write_byte_data(client, INT_MASK,
					  CALIBRATION_DONE | SLEEP_OUT |
					  SLEEP_IN | PROGRAM_LOAD_DONE);
	if (error)
		return error;

	error = i2c_smbus_write_byte_data(client, ERR_MASK,
					  PROGRAM_LOAD_ERR | CPU_TIMEOUT |
					  ADC_TIMEOUT);
	if (error)
		return error;

	/* controller CPU power on */
	error = i2c_smbus_write_byte_data(client, SYSTEM,
					  ANALOG_POWER_ON | CPU_POWER_ON);

	enable_irq(client->irq);

	return error;
}

static int rohm_ts_power_off(struct i2c_client *client)
{
	int error;

	error = i2c_smbus_write_byte_data(client, SYSTEM,
					  ANALOG_POWER_ON | CPU_POWER_OFF);
	if (error) {
		dev_err(&client->dev,
			"failed to power off device CPU: %d\n", error);
		return error;
	}

	error = i2c_smbus_write_byte_data(client, SYSTEM,
					  ANALOG_POWER_OFF | CPU_POWER_OFF);
	if (error)
		dev_err(&client->dev,
			"failed to power off the device: %d\n", error);

	return error;
}

static int rohm_ts_open(struct input_dev *input_dev)
{
	struct rohm_ts_data *ts = input_get_drvdata(input_dev);
	struct i2c_client *client = ts->client;
	int error;

	if (!ts->initialized) {
		error = rohm_ts_device_init(client, ts->setup2);
		if (error) {
			dev_err(&client->dev,
				"device initialization failed: %d\n", error);
			return error;
		}

		ts->initialized = true;
	}

	return 0;
}

static void rohm_ts_close(struct input_dev *input_dev)
{
	struct rohm_ts_data *ts = input_get_drvdata(input_dev);

	rohm_ts_power_off(ts->client);

	ts->initialized = false;
}

static int rohm_bu21023_i2c_probe(struct i2c_client *client,
				  const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct rohm_ts_data *ts;
	struct input_dev *input;
	int error;

	if (!client->irq) {
		dev_err(dev, "IRQ is not assigned\n");
		return -EINVAL;
	}

	if (!client->adapter->algo->master_xfer) {
		dev_err(dev, "I2C level transfers not supported\n");
		return -EOPNOTSUPP;
	}

	/* Turn off CPU just in case */
	error = rohm_ts_power_off(client);
	if (error)
		return error;

	ts = devm_kzalloc(dev, sizeof(struct rohm_ts_data), GFP_KERNEL);
	if (!ts)
		return -ENOMEM;

	ts->client = client;
	ts->setup2 = MAF_1SAMPLE;
	i2c_set_clientdata(client, ts);

	input = devm_input_allocate_device(dev);
	if (!input)
		return -ENOMEM;

	input->name = BU21023_NAME;
	input->id.bustype = BUS_I2C;
	input->open = rohm_ts_open;
	input->close = rohm_ts_close;

	ts->input = input;
	input_set_drvdata(input, ts);

	input_set_abs_params(input, ABS_MT_POSITION_X,
			     ROHM_TS_ABS_X_MIN, ROHM_TS_ABS_X_MAX, 0, 0);
	input_set_abs_params(input, ABS_MT_POSITION_Y,
			     ROHM_TS_ABS_Y_MIN, ROHM_TS_ABS_Y_MAX, 0, 0);

	error = input_mt_init_slots(input, MAX_CONTACTS,
				    INPUT_MT_DIRECT | INPUT_MT_TRACK |
				    INPUT_MT_DROP_UNUSED);
	if (error) {
		dev_err(dev, "failed to multi touch slots initialization\n");
		return error;
	}

	error = devm_request_threaded_irq(dev, client->irq,
					  NULL, rohm_ts_soft_irq,
					  IRQF_ONESHOT, client->name, ts);
	if (error) {
		dev_err(dev, "failed to request IRQ: %d\n", error);
		return error;
	}

	error = input_register_device(input);
	if (error) {
		dev_err(dev, "failed to register input device: %d\n", error);
		return error;
	}

	error = devm_device_add_group(dev, &rohm_ts_attr_group);
	if (error) {
		dev_err(dev, "failed to create sysfs group: %d\n", error);
		return error;
	}

	return error;
}

static const struct i2c_device_id rohm_bu21023_i2c_id[] = {
	{ BU21023_NAME, 0 },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, rohm_bu21023_i2c_id);

static struct i2c_driver rohm_bu21023_i2c_driver = {
	.driver = {
		.name = BU21023_NAME,
	},
	.probe = rohm_bu21023_i2c_probe,
	.id_table = rohm_bu21023_i2c_id,
};
module_i2c_driver(rohm_bu21023_i2c_driver);

MODULE_DESCRIPTION("ROHM BU21023/24 Touchscreen driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("ROHM Co., Ltd."