drivers/input/touchscreen/ti_am335x_tsc.c - kernel/bruno - Git at Google

 /*
  * TI Touch Screen driver
  *
  * Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation version 2.
  *
  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  * kind, whether express or implied; without even the implied warranty
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */


 #include <linux/kernel.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/input.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/of.h>
 #include <linux/of_device.h>

 #include <linux/mfd/ti_am335x_tscadc.h>

 #define ADCFSM_STEPID		0x10
 #define SEQ_SETTLE		275
 #define MAX_12BIT		((1 << 12) - 1)

 static const int config_pins[] = {
 	STEPCONFIG_XPP,
 	STEPCONFIG_XNN,
 	STEPCONFIG_YPP,
 	STEPCONFIG_YNN,
 };

 struct titsc {
 	struct input_dev	*input;
 	struct ti_tscadc_dev	*mfd_tscadc;
 	unsigned int		irq;
 	unsigned int		wires;
 	unsigned int		x_plate_resistance;
 	bool			pen_down;
 	int			coordinate_readouts;
 	u32			config_inp[4];
 	u32			bit_xp, bit_xn, bit_yp, bit_yn;
 	u32			inp_xp, inp_xn, inp_yp, inp_yn;
 	u32			step_mask;
 };

 static unsigned int titsc_readl(struct titsc *ts, unsigned int reg)
 {
 	return readl(ts->mfd_tscadc->tscadc_base + reg);
 }

 static void titsc_writel(struct titsc *tsc, unsigned int reg,
 					unsigned int val)
 {
 	writel(val, tsc->mfd_tscadc->tscadc_base + reg);
 }

 static int titsc_config_wires(struct titsc *ts_dev)
 {
 	u32 analog_line[4];
 	u32 wire_order[4];
 	int i, bit_cfg;

 	for (i = 0; i < 4; i++) {
 		/*
 		 * Get the order in which TSC wires are attached
 		 * w.r.t. each of the analog input lines on the EVM.
 		 */
 		analog_line[i] = (ts_dev->config_inp[i] & 0xF0) >> 4;
 		wire_order[i] = ts_dev->config_inp[i] & 0x0F;
 		if (WARN_ON(analog_line[i] > 7))
 			return -EINVAL;
 		if (WARN_ON(wire_order[i] > ARRAY_SIZE(config_pins)))
 			return -EINVAL;
 	}

 	for (i = 0; i < 4; i++) {
 		int an_line;
 		int wi_order;

 		an_line = analog_line[i];
 		wi_order = wire_order[i];
 		bit_cfg = config_pins[wi_order];
 		if (bit_cfg == 0)
 			return -EINVAL;
 		switch (wi_order) {
 		case 0:
 			ts_dev->bit_xp = bit_cfg;
 			ts_dev->inp_xp = an_line;
 			break;

 		case 1:
 			ts_dev->bit_xn = bit_cfg;
 			ts_dev->inp_xn = an_line;
 			break;

 		case 2:
 			ts_dev->bit_yp = bit_cfg;
 			ts_dev->inp_yp = an_line;
 			break;
 		case 3:
 			ts_dev->bit_yn = bit_cfg;
 			ts_dev->inp_yn = an_line;
 			break;
 		}
 	}
 	return 0;
 }

 static void titsc_step_config(struct titsc *ts_dev)
 {
 	unsigned int	config;
 	int i;
 	int end_step;
 	u32 stepenable;

 	config = STEPCONFIG_MODE_HWSYNC |
 			STEPCONFIG_AVG_16 | ts_dev->bit_xp;
 	switch (ts_dev->wires) {
 	case 4:
 		config |= STEPCONFIG_INP(ts_dev->inp_yp) | ts_dev->bit_xn;
 		break;
 	case 5:
 		config |= ts_dev->bit_yn |
 				STEPCONFIG_INP_AN4 | ts_dev->bit_xn |
 				ts_dev->bit_yp;
 		break;
 	case 8:
 		config |= STEPCONFIG_INP(ts_dev->inp_yp) | ts_dev->bit_xn;
 		break;
 	}

 	/* 1 … coordinate_readouts is for X */
 	end_step = ts_dev->coordinate_readouts;
 	for (i = 0; i < end_step; i++) {
 		titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
 		titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
 	}

 	config = 0;
 	config = STEPCONFIG_MODE_HWSYNC |
 			STEPCONFIG_AVG_16 | ts_dev->bit_yn |
 			STEPCONFIG_INM_ADCREFM;
 	switch (ts_dev->wires) {
 	case 4:
 		config |= ts_dev->bit_yp | STEPCONFIG_INP(ts_dev->inp_xp);
 		break;
 	case 5:
 		config |= ts_dev->bit_xp | STEPCONFIG_INP_AN4 |
 				ts_dev->bit_xn | ts_dev->bit_yp;
 		break;
 	case 8:
 		config |= ts_dev->bit_yp | STEPCONFIG_INP(ts_dev->inp_xp);
 		break;
 	}

 	/* coordinate_readouts … coordinate_readouts * 2 is for Y */
 	end_step = ts_dev->coordinate_readouts * 2;
 	for (i = ts_dev->coordinate_readouts; i < end_step; i++) {
 		titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
 		titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
 	}

 	/* Charge step configuration */
 	config = ts_dev->bit_xp | ts_dev->bit_yn |
 			STEPCHARGE_RFP_XPUL | STEPCHARGE_RFM_XNUR |
 			STEPCHARGE_INM_AN1 | STEPCHARGE_INP(ts_dev->inp_yp);

 	titsc_writel(ts_dev, REG_CHARGECONFIG, config);
 	titsc_writel(ts_dev, REG_CHARGEDELAY, CHARGEDLY_OPENDLY);

 	/* coordinate_readouts * 2 … coordinate_readouts * 2 + 2 is for Z */
 	config = STEPCONFIG_MODE_HWSYNC |
 			STEPCONFIG_AVG_16 | ts_dev->bit_yp |
 			ts_dev->bit_xn | STEPCONFIG_INM_ADCREFM |
 			STEPCONFIG_INP(ts_dev->inp_xp);
 	titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
 	titsc_writel(ts_dev, REG_STEPDELAY(end_step),
 			STEPCONFIG_OPENDLY);

 	end_step++;
 	config |= STEPCONFIG_INP(ts_dev->inp_yn);
 	titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
 	titsc_writel(ts_dev, REG_STEPDELAY(end_step),
 			STEPCONFIG_OPENDLY);

 	/* The steps1 … end and bit 0 for TS_Charge */
 	stepenable = (1 << (end_step + 2)) - 1;
 	ts_dev->step_mask = stepenable;
 	am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
 }

 static void titsc_read_coordinates(struct titsc *ts_dev,
 		u32 *x, u32 *y, u32 *z1, u32 *z2)
 {
 	unsigned int fifocount = titsc_readl(ts_dev, REG_FIFO0CNT);
 	unsigned int prev_val_x = ~0, prev_val_y = ~0;
 	unsigned int prev_diff_x = ~0, prev_diff_y = ~0;
 	unsigned int read, diff;
 	unsigned int i, channel;
 	unsigned int creads = ts_dev->coordinate_readouts;

 	*z1 = *z2 = 0;
 	if (fifocount % (creads * 2 + 2))
 		fifocount -= fifocount % (creads * 2 + 2);
 	/*
 	 * Delta filter is used to remove large variations in sampled
 	 * values from ADC. The filter tries to predict where the next
 	 * coordinate could be. This is done by taking a previous
 	 * coordinate and subtracting it form current one. Further the
 	 * algorithm compares the difference with that of a present value,
 	 * if true the value is reported to the sub system.
 	 */
 	for (i = 0; i < fifocount; i++) {
 		read = titsc_readl(ts_dev, REG_FIFO0);

 		channel = (read & 0xf0000) >> 16;
 		read &= 0xfff;
 		if (channel < creads) {
 			diff = abs(read - prev_val_x);
 			if (diff < prev_diff_x) {
 				prev_diff_x = diff;
 				*x = read;
 			}
 			prev_val_x = read;

 		} else if (channel < creads * 2) {
 			diff = abs(read - prev_val_y);
 			if (diff < prev_diff_y) {
 				prev_diff_y = diff;
 				*y = read;
 			}
 			prev_val_y = read;

 		} else if (channel < creads * 2 + 1) {
 			*z1 = read;

 		} else if (channel < creads * 2 + 2) {
 			*z2 = read;
 		}
 	}
 }

 static irqreturn_t titsc_irq(int irq, void *dev)
 {
 	struct titsc *ts_dev = dev;
 	struct input_dev *input_dev = ts_dev->input;
 	unsigned int status, irqclr = 0;
 	unsigned int x = 0, y = 0;
 	unsigned int z1, z2, z;
 	unsigned int fsm;

 	status = titsc_readl(ts_dev, REG_IRQSTATUS);
 	/*
 	 * ADC and touchscreen share the IRQ line.
 	 * FIFO1 interrupts are used by ADC. Handle FIFO0 IRQs here only
 	 */
 	if (status & IRQENB_FIFO0THRES) {

 		titsc_read_coordinates(ts_dev, &x, &y, &z1, &z2);

 		if (ts_dev->pen_down && z1 != 0 && z2 != 0) {
 			/*
 			 * Calculate pressure using formula
 			 * Resistance(touch) = x plate resistance *
 			 * x postion/4096 * ((z2 / z1) - 1)
 			 */
 			z = z1 - z2;
 			z *= x;
 			z *= ts_dev->x_plate_resistance;
 			z /= z2;
 			z = (z + 2047) >> 12;

 			if (z <= MAX_12BIT) {
 				input_report_abs(input_dev, ABS_X, x);
 				input_report_abs(input_dev, ABS_Y, y);
 				input_report_abs(input_dev, ABS_PRESSURE, z);
 				input_report_key(input_dev, BTN_TOUCH, 1);
 				input_sync(input_dev);
 			}
 		}
 		irqclr |= IRQENB_FIFO0THRES;
 	}

 	/*
 	 * Time for sequencer to settle, to read
 	 * correct state of the sequencer.
 	 */
 	udelay(SEQ_SETTLE);

 	status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
 	if (status & IRQENB_PENUP) {
 		/* Pen up event */
 		fsm = titsc_readl(ts_dev, REG_ADCFSM);
 		if (fsm == ADCFSM_STEPID) {
 			ts_dev->pen_down = false;
 			input_report_key(input_dev, BTN_TOUCH, 0);
 			input_report_abs(input_dev, ABS_PRESSURE, 0);
 			input_sync(input_dev);
 		} else {
 			ts_dev->pen_down = true;
 		}
 		irqclr |= IRQENB_PENUP;
 	}

 	if (status & IRQENB_HW_PEN) {

 		titsc_writel(ts_dev, REG_IRQWAKEUP, 0x00);
 		titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
 	}

 	if (irqclr) {
 		titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);
 		am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
 		return IRQ_HANDLED;
 	}
 	return IRQ_NONE;
 }

 static int titsc_parse_dt(struct platform_device *pdev,
 					struct titsc *ts_dev)
 {
 	struct device_node *node = pdev->dev.of_node;
 	int err;

 	if (!node)
 		return -EINVAL;

 	err = of_property_read_u32(node, "ti,wires", &ts_dev->wires);
 	if (err < 0)
 		return err;
 	switch (ts_dev->wires) {
 	case 4:
 	case 5:
 	case 8:
 		break;
 	default:
 		return -EINVAL;
 	}

 	err = of_property_read_u32(node, "ti,x-plate-resistance",
 			&ts_dev->x_plate_resistance);
 	if (err < 0)
 		return err;

 	/*
 	 * Try with the new binding first. If it fails, try again with
 	 * bogus, miss-spelled version.
 	 */
 	err = of_property_read_u32(node, "ti,coordinate-readouts",
 			&ts_dev->coordinate_readouts);
 	if (err < 0) {
 		dev_warn(&pdev->dev, "please use 'ti,coordinate-readouts' instead\n");
 		err = of_property_read_u32(node, "ti,coordiante-readouts",
 				&ts_dev->coordinate_readouts);
 	}

 	if (err < 0)
 		return err;

 	return of_property_read_u32_array(node, "ti,wire-config",
 			ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp));
 }

 /*
  * The functions for inserting/removing driver as a module.
  */

 static int titsc_probe(struct platform_device *pdev)
 {
 	struct titsc *ts_dev;
 	struct input_dev *input_dev;
 	struct ti_tscadc_dev *tscadc_dev = ti_tscadc_dev_get(pdev);
 	int err;

 	/* Allocate memory for device */
 	ts_dev = kzalloc(sizeof(struct titsc), GFP_KERNEL);
 	input_dev = input_allocate_device();
 	if (!ts_dev || !input_dev) {
 		dev_err(&pdev->dev, "failed to allocate memory.\n");
 		err = -ENOMEM;
 		goto err_free_mem;
 	}

 	tscadc_dev->tsc = ts_dev;
 	ts_dev->mfd_tscadc = tscadc_dev;
 	ts_dev->input = input_dev;
 	ts_dev->irq = tscadc_dev->irq;

 	err = titsc_parse_dt(pdev, ts_dev);
 	if (err) {
 		dev_err(&pdev->dev, "Could not find valid DT data.\n");
 		goto err_free_mem;
 	}

 	err = request_irq(ts_dev->irq, titsc_irq,
 			  IRQF_SHARED, pdev->dev.driver->name, ts_dev);
 	if (err) {
 		dev_err(&pdev->dev, "failed to allocate irq.\n");
 		goto err_free_mem;
 	}

 	titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_FIFO0THRES);
 	err = titsc_config_wires(ts_dev);
 	if (err) {
 		dev_err(&pdev->dev, "wrong i/p wire configuration\n");
 		goto err_free_irq;
 	}
 	titsc_step_config(ts_dev);
 	titsc_writel(ts_dev, REG_FIFO0THR,
 			ts_dev->coordinate_readouts * 2 + 2 - 1);

 	input_dev->name = "ti-tsc";
 	input_dev->dev.parent = &pdev->dev;

 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

 	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
 	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
 	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);

 	/* register to the input system */
 	err = input_register_device(input_dev);
 	if (err)
 		goto err_free_irq;

 	platform_set_drvdata(pdev, ts_dev);
 	return 0;

 err_free_irq:
 	free_irq(ts_dev->irq, ts_dev);
 err_free_mem:
 	input_free_device(input_dev);
 	kfree(ts_dev);
 	return err;
 }

 static int titsc_remove(struct platform_device *pdev)
 {
 	struct titsc *ts_dev = platform_get_drvdata(pdev);
 	u32 steps;

 	free_irq(ts_dev->irq, ts_dev);

 	/* total steps followed by the enable mask */
 	steps = 2 * ts_dev->coordinate_readouts + 2;
 	steps = (1 << steps) - 1;
 	am335x_tsc_se_clr(ts_dev->mfd_tscadc, steps);

 	input_unregister_device(ts_dev->input);

 	kfree(ts_dev);
 	return 0;
 }

 #ifdef CONFIG_PM
 static int titsc_suspend(struct device *dev)
 {
 	struct titsc *ts_dev = dev_get_drvdata(dev);
 	struct ti_tscadc_dev *tscadc_dev;
 	unsigned int idle;

 	tscadc_dev = ti_tscadc_dev_get(to_platform_device(dev));
 	if (device_may_wakeup(tscadc_dev->dev)) {
 		idle = titsc_readl(ts_dev, REG_IRQENABLE);
 		titsc_writel(ts_dev, REG_IRQENABLE,
 				(idle | IRQENB_HW_PEN));
 		titsc_writel(ts_dev, REG_IRQWAKEUP, IRQWKUP_ENB);
 	}
 	return 0;
 }

 static int titsc_resume(struct device *dev)
 {
 	struct titsc *ts_dev = dev_get_drvdata(dev);
 	struct ti_tscadc_dev *tscadc_dev;

 	tscadc_dev = ti_tscadc_dev_get(to_platform_device(dev));
 	if (device_may_wakeup(tscadc_dev->dev)) {
 		titsc_writel(ts_dev, REG_IRQWAKEUP,
 				0x00);
 		titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
 	}
 	titsc_step_config(ts_dev);
 	titsc_writel(ts_dev, REG_FIFO0THR,
 			ts_dev->coordinate_readouts * 2 + 2 - 1);
 	return 0;
 }

 static const struct dev_pm_ops titsc_pm_ops = {
 	.suspend = titsc_suspend,
 	.resume  = titsc_resume,
 };
 #define TITSC_PM_OPS (&titsc_pm_ops)
 #else
 #define TITSC_PM_OPS NULL
 #endif

 static const struct of_device_id ti_tsc_dt_ids[] = {
 	{ .compatible = "ti,am3359-tsc", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ti_tsc_dt_ids);

 static struct platform_driver ti_tsc_driver = {
 	.probe	= titsc_probe,
 	.remove	= titsc_remove,
 	.driver	= {
 		.name   = "TI-am335x-tsc",
 		.pm	= TITSC_PM_OPS,
 		.of_match_table = ti_tsc_dt_ids,
 	},
 };
 module_platform_driver(ti_tsc_driver);

 MODULE_DESCRIPTION("TI touchscreen controller driver");
 MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
 MODULE_LICENSE("GPL");
	/*
	* TI Touch Screen driver
	*
	* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation version 2.
	*
	* This program is distributed "as is" WITHOUT ANY WARRANTY of any
	* kind, whether express or implied; without even the implied warranty
	* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*/


	#include <linux/kernel.h>
	#include <linux/err.h>
	#include <linux/module.h>
	#include <linux/input.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/clk.h>
	#include <linux/platform_device.h>
	#include <linux/io.h>
	#include <linux/delay.h>
	#include <linux/of.h>
	#include <linux/of_device.h>

	#include <linux/mfd/ti_am335x_tscadc.h>

	#define ADCFSM_STEPID 0x10
	#define SEQ_SETTLE 275
	#define MAX_12BIT ((1 << 12) - 1)

	static const int config_pins[] = {
	STEPCONFIG_XPP,
	STEPCONFIG_XNN,
	STEPCONFIG_YPP,
	STEPCONFIG_YNN,
	};

	struct titsc {
	struct input_dev *input;
	struct ti_tscadc_dev *mfd_tscadc;
	unsigned int irq;
	unsigned int wires;
	unsigned int x_plate_resistance;
	bool pen_down;
	int coordinate_readouts;
	u32 config_inp[4];
	u32 bit_xp, bit_xn, bit_yp, bit_yn;
	u32 inp_xp, inp_xn, inp_yp, inp_yn;
	u32 step_mask;
	};

	static unsigned int titsc_readl(struct titsc *ts, unsigned int reg)
	{
	return readl(ts->mfd_tscadc->tscadc_base + reg);
	}

	static void titsc_writel(struct titsc *tsc, unsigned int reg,
	unsigned int val)
	{
	writel(val, tsc->mfd_tscadc->tscadc_base + reg);
	}

	static int titsc_config_wires(struct titsc *ts_dev)
	{
	u32 analog_line[4];
	u32 wire_order[4];
	int i, bit_cfg;

	for (i = 0; i < 4; i++) {
	/*
	* Get the order in which TSC wires are attached
	* w.r.t. each of the analog input lines on the EVM.
	*/
	analog_line[i] = (ts_dev->config_inp[i] & 0xF0) >> 4;
	wire_order[i] = ts_dev->config_inp[i] & 0x0F;
	if (WARN_ON(analog_line[i] > 7))
	return -EINVAL;
	if (WARN_ON(wire_order[i] > ARRAY_SIZE(config_pins)))
	return -EINVAL;
	}

	for (i = 0; i < 4; i++) {
	int an_line;
	int wi_order;

	an_line = analog_line[i];
	wi_order = wire_order[i];
	bit_cfg = config_pins[wi_order];
	if (bit_cfg == 0)
	return -EINVAL;
	switch (wi_order) {
	case 0:
	ts_dev->bit_xp = bit_cfg;
	ts_dev->inp_xp = an_line;
	break;

	case 1:
	ts_dev->bit_xn = bit_cfg;
	ts_dev->inp_xn = an_line;
	break;

	case 2:
	ts_dev->bit_yp = bit_cfg;
	ts_dev->inp_yp = an_line;
	break;
	case 3:
	ts_dev->bit_yn = bit_cfg;
	ts_dev->inp_yn = an_line;
	break;
	}
	}
	return 0;
	}

	static void titsc_step_config(struct titsc *ts_dev)
	{
	unsigned int config;
	int i;
	int end_step;
	u32 stepenable;

	config = STEPCONFIG_MODE_HWSYNC \|
	STEPCONFIG_AVG_16 \| ts_dev->bit_xp;
	switch (ts_dev->wires) {
	case 4:
	config \|= STEPCONFIG_INP(ts_dev->inp_yp) \| ts_dev->bit_xn;
	break;
	case 5:
	config \|= ts_dev->bit_yn \|
	STEPCONFIG_INP_AN4 \| ts_dev->bit_xn \|
	ts_dev->bit_yp;
	break;
	case 8:
	config \|= STEPCONFIG_INP(ts_dev->inp_yp) \| ts_dev->bit_xn;
	break;
	}

	/* 1 … coordinate_readouts is for X */
	end_step = ts_dev->coordinate_readouts;
	for (i = 0; i < end_step; i++) {
	titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
	titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
	}

	config = 0;
	config = STEPCONFIG_MODE_HWSYNC \|
	STEPCONFIG_AVG_16 \| ts_dev->bit_yn \|
	STEPCONFIG_INM_ADCREFM;
	switch (ts_dev->wires) {
	case 4:
	config \|= ts_dev->bit_yp \| STEPCONFIG_INP(ts_dev->inp_xp);
	break;
	case 5:
	config \|= ts_dev->bit_xp \| STEPCONFIG_INP_AN4 \|
	ts_dev->bit_xn \| ts_dev->bit_yp;
	break;
	case 8:
	config \|= ts_dev->bit_yp \| STEPCONFIG_INP(ts_dev->inp_xp);
	break;
	}

	/* coordinate_readouts … coordinate_readouts * 2 is for Y */
	end_step = ts_dev->coordinate_readouts * 2;
	for (i = ts_dev->coordinate_readouts; i < end_step; i++) {
	titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
	titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
	}

	/* Charge step configuration */
	config = ts_dev->bit_xp \| ts_dev->bit_yn \|
	STEPCHARGE_RFP_XPUL \| STEPCHARGE_RFM_XNUR \|
	STEPCHARGE_INM_AN1 \| STEPCHARGE_INP(ts_dev->inp_yp);

	titsc_writel(ts_dev, REG_CHARGECONFIG, config);
	titsc_writel(ts_dev, REG_CHARGEDELAY, CHARGEDLY_OPENDLY);

	/* coordinate_readouts * 2 … coordinate_readouts * 2 + 2 is for Z */
	config = STEPCONFIG_MODE_HWSYNC \|
	STEPCONFIG_AVG_16 \| ts_dev->bit_yp \|
	ts_dev->bit_xn \| STEPCONFIG_INM_ADCREFM \|
	STEPCONFIG_INP(ts_dev->inp_xp);
	titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
	titsc_writel(ts_dev, REG_STEPDELAY(end_step),
	STEPCONFIG_OPENDLY);

	end_step++;
	config \|= STEPCONFIG_INP(ts_dev->inp_yn);
	titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
	titsc_writel(ts_dev, REG_STEPDELAY(end_step),
	STEPCONFIG_OPENDLY);

	/* The steps1 … end and bit 0 for TS_Charge */
	stepenable = (1 << (end_step + 2)) - 1;
	ts_dev->step_mask = stepenable;
	am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
	}

	static void titsc_read_coordinates(struct titsc *ts_dev,
	u32 x, u32 y, u32 z1, u32 z2)
	{
	unsigned int fifocount = titsc_readl(ts_dev, REG_FIFO0CNT);
	unsigned int prev_val_x = ~0, prev_val_y = ~0;
	unsigned int prev_diff_x = ~0, prev_diff_y = ~0;
	unsigned int read, diff;
	unsigned int i, channel;
	unsigned int creads = ts_dev->coordinate_readouts;

	z1 = z2 = 0;
	if (fifocount % (creads * 2 + 2))
	fifocount -= fifocount % (creads * 2 + 2);
	/*
	* Delta filter is used to remove large variations in sampled
	* values from ADC. The filter tries to predict where the next
	* coordinate could be. This is done by taking a previous
	* coordinate and subtracting it form current one. Further the
	* algorithm compares the difference with that of a present value,
	* if true the value is reported to the sub system.
	*/
	for (i = 0; i < fifocount; i++) {
	read = titsc_readl(ts_dev, REG_FIFO0);

	channel = (read & 0xf0000) >> 16;
	read &= 0xfff;
	if (channel < creads) {
	diff = abs(read - prev_val_x);
	if (diff < prev_diff_x) {
	prev_diff_x = diff;
	*x = read;
	}
	prev_val_x = read;

	} else if (channel < creads * 2) {
	diff = abs(read - prev_val_y);
	if (diff < prev_diff_y) {
	prev_diff_y = diff;
	*y = read;
	}
	prev_val_y = read;

	} else if (channel < creads * 2 + 1) {
	*z1 = read;

	} else if (channel < creads * 2 + 2) {
	*z2 = read;
	}
	}
	}

	static irqreturn_t titsc_irq(int irq, void *dev)
	{
	struct titsc *ts_dev = dev;
	struct input_dev *input_dev = ts_dev->input;
	unsigned int status, irqclr = 0;
	unsigned int x = 0, y = 0;
	unsigned int z1, z2, z;
	unsigned int fsm;

	status = titsc_readl(ts_dev, REG_IRQSTATUS);
	/*
	* ADC and touchscreen share the IRQ line.
	* FIFO1 interrupts are used by ADC. Handle FIFO0 IRQs here only
	*/
	if (status & IRQENB_FIFO0THRES) {

	titsc_read_coordinates(ts_dev, &x, &y, &z1, &z2);

	if (ts_dev->pen_down && z1 != 0 && z2 != 0) {
	/*
	* Calculate pressure using formula
	* Resistance(touch) = x plate resistance *
	* x postion/4096 * ((z2 / z1) - 1)
	*/
	z = z1 - z2;
	z *= x;
	z *= ts_dev->x_plate_resistance;
	z /= z2;
	z = (z + 2047) >> 12;

	if (z <= MAX_12BIT) {
	input_report_abs(input_dev, ABS_X, x);
	input_report_abs(input_dev, ABS_Y, y);
	input_report_abs(input_dev, ABS_PRESSURE, z);
	input_report_key(input_dev, BTN_TOUCH, 1);
	input_sync(input_dev);
	}
	}
	irqclr \|= IRQENB_FIFO0THRES;
	}

	/*
	* Time for sequencer to settle, to read
	* correct state of the sequencer.
	*/
	udelay(SEQ_SETTLE);

	status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
	if (status & IRQENB_PENUP) {
	/* Pen up event */
	fsm = titsc_readl(ts_dev, REG_ADCFSM);
	if (fsm == ADCFSM_STEPID) {
	ts_dev->pen_down = false;
	input_report_key(input_dev, BTN_TOUCH, 0);
	input_report_abs(input_dev, ABS_PRESSURE, 0);
	input_sync(input_dev);
	} else {
	ts_dev->pen_down = true;
	}
	irqclr \|= IRQENB_PENUP;
	}

	if (status & IRQENB_HW_PEN) {

	titsc_writel(ts_dev, REG_IRQWAKEUP, 0x00);
	titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
	}

	if (irqclr) {
	titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);
	am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
	return IRQ_HANDLED;
	}
	return IRQ_NONE;
	}

	static int titsc_parse_dt(struct platform_device *pdev,
	struct titsc *ts_dev)
	{
	struct device_node *node = pdev->dev.of_node;
	int err;

	if (!node)
	return -EINVAL;

	err = of_property_read_u32(node, "ti,wires", &ts_dev->wires);
	if (err < 0)
	return err;
	switch (ts_dev->wires) {
	case 4:
	case 5:
	case 8:
	break;
	default:
	return -EINVAL;
	}

	err = of_property_read_u32(node, "ti,x-plate-resistance",
	&ts_dev->x_plate_resistance);
	if (err < 0)
	return err;

	/*
	* Try with the new binding first. If it fails, try again with
	* bogus, miss-spelled version.
	*/
	err = of_property_read_u32(node, "ti,coordinate-readouts",
	&ts_dev->coordinate_readouts);
	if (err < 0) {
	dev_warn(&pdev->dev, "please use 'ti,coordinate-readouts' instead\n");
	err = of_property_read_u32(node, "ti,coordiante-readouts",
	&ts_dev->coordinate_readouts);
	}

	if (err < 0)
	return err;

	return of_property_read_u32_array(node, "ti,wire-config",
	ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp));
	}

	/*
	* The functions for inserting/removing driver as a module.
	*/

	static int titsc_probe(struct platform_device *pdev)
	{
	struct titsc *ts_dev;
	struct input_dev *input_dev;
	struct ti_tscadc_dev *tscadc_dev = ti_tscadc_dev_get(pdev);
	int err;

	/* Allocate memory for device */
	ts_dev = kzalloc(sizeof(struct titsc), GFP_KERNEL);
	input_dev = input_allocate_device();
	if (!ts_dev \|\| !input_dev) {
	dev_err(&pdev->dev, "failed to allocate memory.\n");
	err = -ENOMEM;
	goto err_free_mem;
	}

	tscadc_dev->tsc = ts_dev;
	ts_dev->mfd_tscadc = tscadc_dev;
	ts_dev->input = input_dev;
	ts_dev->irq = tscadc_dev->irq;

	err = titsc_parse_dt(pdev, ts_dev);
	if (err) {
	dev_err(&pdev->dev, "Could not find valid DT data.\n");
	goto err_free_mem;
	}

	err = request_irq(ts_dev->irq, titsc_irq,
	IRQF_SHARED, pdev->dev.driver->name, ts_dev);
	if (err) {
	dev_err(&pdev->dev, "failed to allocate irq.\n");
	goto err_free_mem;
	}

	titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_FIFO0THRES);
	err = titsc_config_wires(ts_dev);
	if (err) {
	dev_err(&pdev->dev, "wrong i/p wire configuration\n");
	goto err_free_irq;
	}
	titsc_step_config(ts_dev);
	titsc_writel(ts_dev, REG_FIFO0THR,
	ts_dev->coordinate_readouts * 2 + 2 - 1);

	input_dev->name = "ti-tsc";
	input_dev->dev.parent = &pdev->dev;

	input_dev->evbit[0] = BIT_MASK(EV_KEY) \| BIT_MASK(EV_ABS);
	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);

	/* register to the input system */
	err = input_register_device(input_dev);
	if (err)
	goto err_free_irq;

	platform_set_drvdata(pdev, ts_dev);
	return 0;

	err_free_irq:
	free_irq(ts_dev->irq, ts_dev);
	err_free_mem:
	input_free_device(input_dev);
	kfree(ts_dev);
	return err;
	}

	static int titsc_remove(struct platform_device *pdev)
	{
	struct titsc *ts_dev = platform_get_drvdata(pdev);
	u32 steps;

	free_irq(ts_dev->irq, ts_dev);

	/* total steps followed by the enable mask */
	steps = 2 * ts_dev->coordinate_readouts + 2;
	steps = (1 << steps) - 1;
	am335x_tsc_se_clr(ts_dev->mfd_tscadc, steps);

	input_unregister_device(ts_dev->input);

	kfree(ts_dev);
	return 0;
	}

	#ifdef CONFIG_PM
	static int titsc_suspend(struct device *dev)
	{
	struct titsc *ts_dev = dev_get_drvdata(dev);
	struct ti_tscadc_dev *tscadc_dev;
	unsigned int idle;

	tscadc_dev = ti_tscadc_dev_get(to_platform_device(dev));
	if (device_may_wakeup(tscadc_dev->dev)) {
	idle = titsc_readl(ts_dev, REG_IRQENABLE);
	titsc_writel(ts_dev, REG_IRQENABLE,
	(idle \| IRQENB_HW_PEN));
	titsc_writel(ts_dev, REG_IRQWAKEUP, IRQWKUP_ENB);
	}
	return 0;
	}

	static int titsc_resume(struct device *dev)
	{
	struct titsc *ts_dev = dev_get_drvdata(dev);
	struct ti_tscadc_dev *tscadc_dev;

	tscadc_dev = ti_tscadc_dev_get(to_platform_device(dev));
	if (device_may_wakeup(tscadc_dev->dev)) {
	titsc_writel(ts_dev, REG_IRQWAKEUP,
	0x00);
	titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
	}
	titsc_step_config(ts_dev);
	titsc_writel(ts_dev, REG_FIFO0THR,
	ts_dev->coordinate_readouts * 2 + 2 - 1);
	return 0;
	}

	static const struct dev_pm_ops titsc_pm_ops = {
	.suspend = titsc_suspend,
	.resume = titsc_resume,
	};
	#define TITSC_PM_OPS (&titsc_pm_ops)
	#else
	#define TITSC_PM_OPS NULL
	#endif

	static const struct of_device_id ti_tsc_dt_ids[] = {
	{ .compatible = "ti,am3359-tsc", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, ti_tsc_dt_ids);

	static struct platform_driver ti_tsc_driver = {
	.probe = titsc_probe,
	.remove = titsc_remove,
	.driver = {
	.name = "TI-am335x-tsc",
	.pm = TITSC_PM_OPS,
	.of_match_table = ti_tsc_dt_ids,
	},
	};
	module_platform_driver(ti_tsc_driver);

	MODULE_DESCRIPTION("TI touchscreen controller driver");
	MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
	MODULE_LICENSE("GPL");