drivers/input/touchscreen/fsl-imx25-tcq.c - pub/scm/linux/kernel/git/mdf/linux-fpga - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 //
 // Copyright (C) 2014-2015 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
 // Based on driver from 2011:
 //   Juergen Beisert, Pengutronix <kernel@pengutronix.de>
 //
 // This is the driver for the imx25 TCQ (Touchscreen Conversion Queue)
 // connected to the imx25 ADC.

 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/mfd/imx25-tsadc.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>

 static const char mx25_tcq_name[] = "mx25-tcq";

 enum mx25_tcq_mode {
 	MX25_TS_4WIRE,
 };

 struct mx25_tcq_priv {
 	struct regmap *regs;
 	struct regmap *core_regs;
 	struct input_dev *idev;
 	enum mx25_tcq_mode mode;
 	unsigned int pen_threshold;
 	unsigned int sample_count;
 	unsigned int expected_samples;
 	unsigned int pen_debounce;
 	unsigned int settling_time;
 	struct clk *clk;
 	int irq;
 	struct device *dev;
 };

 static struct regmap_config mx25_tcq_regconfig = {
 	.fast_io = true,
 	.max_register = 0x5c,
 	.reg_bits = 32,
 	.val_bits = 32,
 	.reg_stride = 4,
 };

 static const struct of_device_id mx25_tcq_ids[] = {
 	{ .compatible = "fsl,imx25-tcq", },
 	{ /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, mx25_tcq_ids);

 #define TSC_4WIRE_PRE_INDEX 0
 #define TSC_4WIRE_X_INDEX 1
 #define TSC_4WIRE_Y_INDEX 2
 #define TSC_4WIRE_POST_INDEX 3
 #define TSC_4WIRE_LEAVE 4

 #define MX25_TSC_DEF_THRESHOLD 80
 #define TSC_MAX_SAMPLES 16

 #define MX25_TSC_REPEAT_WAIT 14

 enum mx25_adc_configurations {
 	MX25_CFG_PRECHARGE = 0,
 	MX25_CFG_TOUCH_DETECT,
 	MX25_CFG_X_MEASUREMENT,
 	MX25_CFG_Y_MEASUREMENT,
 };

 #define MX25_PRECHARGE_VALUE (\
 			MX25_ADCQ_CFG_YPLL_OFF | \
 			MX25_ADCQ_CFG_XNUR_OFF | \
 			MX25_ADCQ_CFG_XPUL_HIGH | \
 			MX25_ADCQ_CFG_REFP_INT | \
 			MX25_ADCQ_CFG_IN_XP | \
 			MX25_ADCQ_CFG_REFN_NGND2 | \
 			MX25_ADCQ_CFG_IGS)

 #define MX25_TOUCH_DETECT_VALUE (\
 			MX25_ADCQ_CFG_YNLR | \
 			MX25_ADCQ_CFG_YPLL_OFF | \
 			MX25_ADCQ_CFG_XNUR_OFF | \
 			MX25_ADCQ_CFG_XPUL_OFF | \
 			MX25_ADCQ_CFG_REFP_INT | \
 			MX25_ADCQ_CFG_IN_XP | \
 			MX25_ADCQ_CFG_REFN_NGND2 | \
 			MX25_ADCQ_CFG_PENIACK)

 static void imx25_setup_queue_cfgs(struct mx25_tcq_priv *priv,
 				   unsigned int settling_cnt)
 {
 	u32 precharge_cfg =
 			MX25_PRECHARGE_VALUE |
 			MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);
 	u32 touch_detect_cfg =
 			MX25_TOUCH_DETECT_VALUE |
 			MX25_ADCQ_CFG_NOS(1) |
 			MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);

 	regmap_write(priv->core_regs, MX25_TSC_TICR, precharge_cfg);

 	/* PRECHARGE */
 	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_PRECHARGE),
 		     precharge_cfg);

 	/* TOUCH_DETECT */
 	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_TOUCH_DETECT),
 		     touch_detect_cfg);

 	/* X Measurement */
 	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_X_MEASUREMENT),
 		     MX25_ADCQ_CFG_YPLL_OFF |
 		     MX25_ADCQ_CFG_XNUR_LOW |
 		     MX25_ADCQ_CFG_XPUL_HIGH |
 		     MX25_ADCQ_CFG_REFP_XP |
 		     MX25_ADCQ_CFG_IN_YP |
 		     MX25_ADCQ_CFG_REFN_XN |
 		     MX25_ADCQ_CFG_NOS(priv->sample_count) |
 		     MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));

 	/* Y Measurement */
 	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_Y_MEASUREMENT),
 		     MX25_ADCQ_CFG_YNLR |
 		     MX25_ADCQ_CFG_YPLL_HIGH |
 		     MX25_ADCQ_CFG_XNUR_OFF |
 		     MX25_ADCQ_CFG_XPUL_OFF |
 		     MX25_ADCQ_CFG_REFP_YP |
 		     MX25_ADCQ_CFG_IN_XP |
 		     MX25_ADCQ_CFG_REFN_YN |
 		     MX25_ADCQ_CFG_NOS(priv->sample_count) |
 		     MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));

 	/* Enable the touch detection right now */
 	regmap_write(priv->core_regs, MX25_TSC_TICR, touch_detect_cfg |
 		     MX25_ADCQ_CFG_IGS);
 }

 static int imx25_setup_queue_4wire(struct mx25_tcq_priv *priv,
 				   unsigned settling_cnt, int *items)
 {
 	imx25_setup_queue_cfgs(priv, settling_cnt);

 	/* Setup the conversion queue */
 	regmap_write(priv->regs, MX25_ADCQ_ITEM_7_0,
 		     MX25_ADCQ_ITEM(0, MX25_CFG_PRECHARGE) |
 		     MX25_ADCQ_ITEM(1, MX25_CFG_TOUCH_DETECT) |
 		     MX25_ADCQ_ITEM(2, MX25_CFG_X_MEASUREMENT) |
 		     MX25_ADCQ_ITEM(3, MX25_CFG_Y_MEASUREMENT) |
 		     MX25_ADCQ_ITEM(4, MX25_CFG_PRECHARGE) |
 		     MX25_ADCQ_ITEM(5, MX25_CFG_TOUCH_DETECT));

 	/*
 	 * We measure X/Y with 'sample_count' number of samples and execute a
 	 * touch detection twice, with 1 sample each
 	 */
 	priv->expected_samples = priv->sample_count * 2 + 2;
 	*items = 6;

 	return 0;
 }

 static void mx25_tcq_disable_touch_irq(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK,
 			   MX25_ADCQ_CR_PDMSK);
 }

 static void mx25_tcq_enable_touch_irq(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK, 0);
 }

 static void mx25_tcq_disable_fifo_irq(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ,
 			   MX25_ADCQ_MR_FDRY_IRQ);
 }

 static void mx25_tcq_enable_fifo_irq(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ, 0);
 }

 static void mx25_tcq_force_queue_start(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
 			   MX25_ADCQ_CR_FQS,
 			   MX25_ADCQ_CR_FQS);
 }

 static void mx25_tcq_force_queue_stop(struct mx25_tcq_priv *priv)
 {
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
 			   MX25_ADCQ_CR_FQS, 0);
 }

 static void mx25_tcq_fifo_reset(struct mx25_tcq_priv *priv)
 {
 	u32 tcqcr;

 	regmap_read(priv->regs, MX25_ADCQ_CR, &tcqcr);
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST,
 			   MX25_ADCQ_CR_FRST);
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST, 0);
 	regmap_write(priv->regs, MX25_ADCQ_CR, tcqcr);
 }

 static void mx25_tcq_re_enable_touch_detection(struct mx25_tcq_priv *priv)
 {
 	/* stop the queue from looping */
 	mx25_tcq_force_queue_stop(priv);

 	/* for a clean touch detection, preload the X plane */
 	regmap_write(priv->core_regs, MX25_TSC_TICR, MX25_PRECHARGE_VALUE);

 	/* waste some time now to pre-load the X plate to high voltage */
 	mx25_tcq_fifo_reset(priv);

 	/* re-enable the detection right now */
 	regmap_write(priv->core_regs, MX25_TSC_TICR,
 		     MX25_TOUCH_DETECT_VALUE | MX25_ADCQ_CFG_IGS);

 	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_PD,
 			   MX25_ADCQ_SR_PD);

 	/* enable the pen down event to be a source for the interrupt */
 	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_PD_IRQ, 0);

 	/* lets fire the next IRQ if someone touches the touchscreen */
 	mx25_tcq_enable_touch_irq(priv);
 }

 static void mx25_tcq_create_event_for_4wire(struct mx25_tcq_priv *priv,
 					    u32 *sample_buf,
 					    unsigned int samples)
 {
 	unsigned int x_pos = 0;
 	unsigned int y_pos = 0;
 	unsigned int touch_pre = 0;
 	unsigned int touch_post = 0;
 	unsigned int i;

 	for (i = 0; i < samples; i++) {
 		unsigned int index = MX25_ADCQ_FIFO_ID(sample_buf[i]);
 		unsigned int val = MX25_ADCQ_FIFO_DATA(sample_buf[i]);

 		switch (index) {
 		case 1:
 			touch_pre = val;
 			break;
 		case 2:
 			x_pos = val;
 			break;
 		case 3:
 			y_pos = val;
 			break;
 		case 5:
 			touch_post = val;
 			break;
 		default:
 			dev_dbg(priv->dev, "Dropped samples because of invalid index %d\n",
 				index);
 			return;
 		}
 	}

 	if (samples != 0) {
 		/*
 		 * only if both touch measures are below a threshold,
 		 * the position is valid
 		 */
 		if (touch_pre < priv->pen_threshold &&
 		    touch_post < priv->pen_threshold) {
 			/* valid samples, generate a report */
 			x_pos /= priv->sample_count;
 			y_pos /= priv->sample_count;
 			input_report_abs(priv->idev, ABS_X, x_pos);
 			input_report_abs(priv->idev, ABS_Y, y_pos);
 			input_report_key(priv->idev, BTN_TOUCH, 1);
 			input_sync(priv->idev);

 			/* get next sample */
 			mx25_tcq_enable_fifo_irq(priv);
 		} else if (touch_pre >= priv->pen_threshold &&
 			   touch_post >= priv->pen_threshold) {
 			/*
 			 * if both samples are invalid,
 			 * generate a release report
 			 */
 			input_report_key(priv->idev, BTN_TOUCH, 0);
 			input_sync(priv->idev);
 			mx25_tcq_re_enable_touch_detection(priv);
 		} else {
 			/*
 			 * if only one of both touch measurements are
 			 * below the threshold, still some bouncing
 			 * happens. Take additional samples in this
 			 * case to be sure
 			 */
 			mx25_tcq_enable_fifo_irq(priv);
 		}
 	}
 }

 static irqreturn_t mx25_tcq_irq_thread(int irq, void *dev_id)
 {
 	struct mx25_tcq_priv *priv = dev_id;
 	u32 sample_buf[TSC_MAX_SAMPLES];
 	unsigned int samples;
 	u32 stats;
 	unsigned int i;

 	/*
 	 * Check how many samples are available. We always have to read exactly
 	 * sample_count samples from the fifo, or a multiple of sample_count.
 	 * Otherwise we mixup samples into different touch events.
 	 */
 	regmap_read(priv->regs, MX25_ADCQ_SR, &stats);
 	samples = MX25_ADCQ_SR_FDN(stats);
 	samples -= samples % priv->sample_count;

 	if (!samples)
 		return IRQ_HANDLED;

 	for (i = 0; i != samples; ++i)
 		regmap_read(priv->regs, MX25_ADCQ_FIFO, &sample_buf[i]);

 	mx25_tcq_create_event_for_4wire(priv, sample_buf, samples);

 	return IRQ_HANDLED;
 }

 static irqreturn_t mx25_tcq_irq(int irq, void *dev_id)
 {
 	struct mx25_tcq_priv *priv = dev_id;
 	u32 stat;
 	int ret = IRQ_HANDLED;

 	regmap_read(priv->regs, MX25_ADCQ_SR, &stat);

 	if (stat & (MX25_ADCQ_SR_FRR | MX25_ADCQ_SR_FUR | MX25_ADCQ_SR_FOR))
 		mx25_tcq_re_enable_touch_detection(priv);

 	if (stat & MX25_ADCQ_SR_PD) {
 		mx25_tcq_disable_touch_irq(priv);
 		mx25_tcq_force_queue_start(priv);
 		mx25_tcq_enable_fifo_irq(priv);
 	}

 	if (stat & MX25_ADCQ_SR_FDRY) {
 		mx25_tcq_disable_fifo_irq(priv);
 		ret = IRQ_WAKE_THREAD;
 	}

 	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_FRR |
 			   MX25_ADCQ_SR_FUR | MX25_ADCQ_SR_FOR |
 			   MX25_ADCQ_SR_PD,
 			   MX25_ADCQ_SR_FRR | MX25_ADCQ_SR_FUR |
 			   MX25_ADCQ_SR_FOR | MX25_ADCQ_SR_PD);

 	return ret;
 }

 /* configure the state machine for a 4-wire touchscreen */
 static int mx25_tcq_init(struct mx25_tcq_priv *priv)
 {
 	u32 tgcr;
 	unsigned int ipg_div;
 	unsigned int adc_period;
 	unsigned int debounce_cnt;
 	unsigned int settling_cnt;
 	int itemct;
 	int error;

 	regmap_read(priv->core_regs, MX25_TSC_TGCR, &tgcr);
 	ipg_div = max_t(unsigned int, 4, MX25_TGCR_GET_ADCCLK(tgcr));
 	adc_period = USEC_PER_SEC * ipg_div * 2 + 2;
 	adc_period /= clk_get_rate(priv->clk) / 1000 + 1;
 	debounce_cnt = DIV_ROUND_UP(priv->pen_debounce, adc_period * 8) - 1;
 	settling_cnt = DIV_ROUND_UP(priv->settling_time, adc_period * 8) - 1;

 	/* Reset */
 	regmap_write(priv->regs, MX25_ADCQ_CR,
 		     MX25_ADCQ_CR_QRST | MX25_ADCQ_CR_FRST);
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
 			   MX25_ADCQ_CR_QRST | MX25_ADCQ_CR_FRST, 0);

 	/* up to 128 * 8 ADC clocks are possible */
 	if (debounce_cnt > 127)
 		debounce_cnt = 127;

 	/* up to 255 * 8 ADC clocks are possible */
 	if (settling_cnt > 255)
 		settling_cnt = 255;

 	error = imx25_setup_queue_4wire(priv, settling_cnt, &itemct);
 	if (error)
 		return error;

 	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
 			   MX25_ADCQ_CR_LITEMID_MASK | MX25_ADCQ_CR_WMRK_MASK,
 			   MX25_ADCQ_CR_LITEMID(itemct - 1) |
 			   MX25_ADCQ_CR_WMRK(priv->expected_samples - 1));

 	/* setup debounce count */
 	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR,
 			   MX25_TGCR_PDBTIME_MASK,
 			   MX25_TGCR_PDBTIME(debounce_cnt));

 	/* enable debounce */
 	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDBEN,
 			   MX25_TGCR_PDBEN);
 	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDEN,
 			   MX25_TGCR_PDEN);

 	/* enable the engine on demand */
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_QSM_MASK,
 			   MX25_ADCQ_CR_QSM_FQS);

 	/* Enable repeat and repeat wait */
 	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
 			   MX25_ADCQ_CR_RPT | MX25_ADCQ_CR_RWAIT_MASK,
 			   MX25_ADCQ_CR_RPT |
 			   MX25_ADCQ_CR_RWAIT(MX25_TSC_REPEAT_WAIT));

 	return 0;
 }

 static int mx25_tcq_parse_dt(struct platform_device *pdev,
 			     struct mx25_tcq_priv *priv)
 {
 	struct device_node *np = pdev->dev.of_node;
 	u32 wires;
 	int error;

 	/* Setup defaults */
 	priv->pen_threshold = 500;
 	priv->sample_count = 3;
 	priv->pen_debounce = 1000000;
 	priv->settling_time = 250000;

 	error = of_property_read_u32(np, "fsl,wires", &wires);
 	if (error) {
 		dev_err(&pdev->dev, "Failed to find fsl,wires properties\n");
 		return error;
 	}

 	if (wires == 4) {
 		priv->mode = MX25_TS_4WIRE;
 	} else {
 		dev_err(&pdev->dev, "%u-wire mode not supported\n", wires);
 		return -EINVAL;
 	}

 	/* These are optional, we don't care about the return values */
 	of_property_read_u32(np, "fsl,pen-threshold", &priv->pen_threshold);
 	of_property_read_u32(np, "fsl,settling-time-ns", &priv->settling_time);
 	of_property_read_u32(np, "fsl,pen-debounce-ns", &priv->pen_debounce);

 	return 0;
 }

 static int mx25_tcq_open(struct input_dev *idev)
 {
 	struct device *dev = &idev->dev;
 	struct mx25_tcq_priv *priv = dev_get_drvdata(dev);
 	int error;

 	error = clk_prepare_enable(priv->clk);
 	if (error) {
 		dev_err(dev, "Failed to enable ipg clock\n");
 		return error;
 	}

 	error = mx25_tcq_init(priv);
 	if (error) {
 		dev_err(dev, "Failed to init tcq\n");
 		clk_disable_unprepare(priv->clk);
 		return error;
 	}

 	mx25_tcq_re_enable_touch_detection(priv);

 	return 0;
 }

 static void mx25_tcq_close(struct input_dev *idev)
 {
 	struct mx25_tcq_priv *priv = input_get_drvdata(idev);

 	mx25_tcq_force_queue_stop(priv);
 	mx25_tcq_disable_touch_irq(priv);
 	mx25_tcq_disable_fifo_irq(priv);
 	clk_disable_unprepare(priv->clk);
 }

 static int mx25_tcq_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct input_dev *idev;
 	struct mx25_tcq_priv *priv;
 	struct mx25_tsadc *tsadc = dev_get_drvdata(dev->parent);
 	void __iomem *mem;
 	int error;

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 	priv->dev = dev;

 	mem = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(mem))
 		return PTR_ERR(mem);

 	error = mx25_tcq_parse_dt(pdev, priv);
 	if (error)
 		return error;

 	priv->regs = devm_regmap_init_mmio(dev, mem, &mx25_tcq_regconfig);
 	if (IS_ERR(priv->regs)) {
 		dev_err(dev, "Failed to initialize regmap\n");
 		return PTR_ERR(priv->regs);
 	}

 	priv->irq = platform_get_irq(pdev, 0);
 	if (priv->irq <= 0)
 		return priv->irq;

 	idev = devm_input_allocate_device(dev);
 	if (!idev) {
 		dev_err(dev, "Failed to allocate input device\n");
 		return -ENOMEM;
 	}

 	idev->name = mx25_tcq_name;
 	input_set_capability(idev, EV_KEY, BTN_TOUCH);
 	input_set_abs_params(idev, ABS_X, 0, 0xfff, 0, 0);
 	input_set_abs_params(idev, ABS_Y, 0, 0xfff, 0, 0);

 	idev->id.bustype = BUS_HOST;
 	idev->open = mx25_tcq_open;
 	idev->close = mx25_tcq_close;

 	priv->idev = idev;
 	input_set_drvdata(idev, priv);

 	priv->core_regs = tsadc->regs;
 	if (!priv->core_regs)
 		return -EINVAL;

 	priv->clk = tsadc->clk;
 	if (!priv->clk)
 		return -EINVAL;

 	platform_set_drvdata(pdev, priv);

 	error = devm_request_threaded_irq(dev, priv->irq, mx25_tcq_irq,
 					  mx25_tcq_irq_thread, 0, pdev->name,
 					  priv);
 	if (error) {
 		dev_err(dev, "Failed requesting IRQ\n");
 		return error;
 	}

 	error = input_register_device(idev);
 	if (error) {
 		dev_err(dev, "Failed to register input device\n");
 		return error;
 	}

 	return 0;
 }

 static struct platform_driver mx25_tcq_driver = {
 	.driver		= {
 		.name	= "mx25-tcq",
 		.of_match_table = mx25_tcq_ids,
 	},
 	.probe		= mx25_tcq_probe,
 };
 module_platform_driver(mx25_tcq_driver);

 MODULE_DESCRIPTION("TS input driver for Freescale mx25");
 MODULE_AUTHOR("Markus Pargmann <mpa@pengutronix.de>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	//
	// Copyright (C) 2014-2015 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
	// Based on driver from 2011:
	// Juergen Beisert, Pengutronix <kernel@pengutronix.de>
	//
	// This is the driver for the imx25 TCQ (Touchscreen Conversion Queue)
	// connected to the imx25 ADC.

	#include <linux/clk.h>
	#include <linux/device.h>
	#include <linux/input.h>
	#include <linux/interrupt.h>
	#include <linux/mfd/imx25-tsadc.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>

	static const char mx25_tcq_name[] = "mx25-tcq";

	enum mx25_tcq_mode {
	MX25_TS_4WIRE,
	};

	struct mx25_tcq_priv {
	struct regmap *regs;
	struct regmap *core_regs;
	struct input_dev *idev;
	enum mx25_tcq_mode mode;
	unsigned int pen_threshold;
	unsigned int sample_count;
	unsigned int expected_samples;
	unsigned int pen_debounce;
	unsigned int settling_time;
	struct clk *clk;
	int irq;
	struct device *dev;
	};

	static struct regmap_config mx25_tcq_regconfig = {
	.fast_io = true,
	.max_register = 0x5c,
	.reg_bits = 32,
	.val_bits = 32,
	.reg_stride = 4,
	};

	static const struct of_device_id mx25_tcq_ids[] = {
	{ .compatible = "fsl,imx25-tcq", },
	{ /* Sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, mx25_tcq_ids);

	#define TSC_4WIRE_PRE_INDEX 0
	#define TSC_4WIRE_X_INDEX 1
	#define TSC_4WIRE_Y_INDEX 2
	#define TSC_4WIRE_POST_INDEX 3
	#define TSC_4WIRE_LEAVE 4

	#define MX25_TSC_DEF_THRESHOLD 80
	#define TSC_MAX_SAMPLES 16

	#define MX25_TSC_REPEAT_WAIT 14

	enum mx25_adc_configurations {
	MX25_CFG_PRECHARGE = 0,
	MX25_CFG_TOUCH_DETECT,
	MX25_CFG_X_MEASUREMENT,
	MX25_CFG_Y_MEASUREMENT,
	};

	#define MX25_PRECHARGE_VALUE (\
	MX25_ADCQ_CFG_YPLL_OFF \| \
	MX25_ADCQ_CFG_XNUR_OFF \| \
	MX25_ADCQ_CFG_XPUL_HIGH \| \
	MX25_ADCQ_CFG_REFP_INT \| \
	MX25_ADCQ_CFG_IN_XP \| \
	MX25_ADCQ_CFG_REFN_NGND2 \| \
	MX25_ADCQ_CFG_IGS)

	#define MX25_TOUCH_DETECT_VALUE (\
	MX25_ADCQ_CFG_YNLR \| \
	MX25_ADCQ_CFG_YPLL_OFF \| \
	MX25_ADCQ_CFG_XNUR_OFF \| \
	MX25_ADCQ_CFG_XPUL_OFF \| \
	MX25_ADCQ_CFG_REFP_INT \| \
	MX25_ADCQ_CFG_IN_XP \| \
	MX25_ADCQ_CFG_REFN_NGND2 \| \
	MX25_ADCQ_CFG_PENIACK)

	static void imx25_setup_queue_cfgs(struct mx25_tcq_priv *priv,
	unsigned int settling_cnt)
	{
	u32 precharge_cfg =
	MX25_PRECHARGE_VALUE \|
	MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);
	u32 touch_detect_cfg =
	MX25_TOUCH_DETECT_VALUE \|
	MX25_ADCQ_CFG_NOS(1) \|
	MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt);

	regmap_write(priv->core_regs, MX25_TSC_TICR, precharge_cfg);

	/* PRECHARGE */
	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_PRECHARGE),
	precharge_cfg);

	/* TOUCH_DETECT */
	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_TOUCH_DETECT),
	touch_detect_cfg);

	/* X Measurement */
	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_X_MEASUREMENT),
	MX25_ADCQ_CFG_YPLL_OFF \|
	MX25_ADCQ_CFG_XNUR_LOW \|
	MX25_ADCQ_CFG_XPUL_HIGH \|
	MX25_ADCQ_CFG_REFP_XP \|
	MX25_ADCQ_CFG_IN_YP \|
	MX25_ADCQ_CFG_REFN_XN \|
	MX25_ADCQ_CFG_NOS(priv->sample_count) \|
	MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));

	/* Y Measurement */
	regmap_write(priv->regs, MX25_ADCQ_CFG(MX25_CFG_Y_MEASUREMENT),
	MX25_ADCQ_CFG_YNLR \|
	MX25_ADCQ_CFG_YPLL_HIGH \|
	MX25_ADCQ_CFG_XNUR_OFF \|
	MX25_ADCQ_CFG_XPUL_OFF \|
	MX25_ADCQ_CFG_REFP_YP \|
	MX25_ADCQ_CFG_IN_XP \|
	MX25_ADCQ_CFG_REFN_YN \|
	MX25_ADCQ_CFG_NOS(priv->sample_count) \|
	MX25_ADCQ_CFG_SETTLING_TIME(settling_cnt));

	/* Enable the touch detection right now */
	regmap_write(priv->core_regs, MX25_TSC_TICR, touch_detect_cfg \|
	MX25_ADCQ_CFG_IGS);
	}

	static int imx25_setup_queue_4wire(struct mx25_tcq_priv *priv,
	unsigned settling_cnt, int *items)
	{
	imx25_setup_queue_cfgs(priv, settling_cnt);

	/* Setup the conversion queue */
	regmap_write(priv->regs, MX25_ADCQ_ITEM_7_0,
	MX25_ADCQ_ITEM(0, MX25_CFG_PRECHARGE) \|
	MX25_ADCQ_ITEM(1, MX25_CFG_TOUCH_DETECT) \|
	MX25_ADCQ_ITEM(2, MX25_CFG_X_MEASUREMENT) \|
	MX25_ADCQ_ITEM(3, MX25_CFG_Y_MEASUREMENT) \|
	MX25_ADCQ_ITEM(4, MX25_CFG_PRECHARGE) \|
	MX25_ADCQ_ITEM(5, MX25_CFG_TOUCH_DETECT));

	/*
	* We measure X/Y with 'sample_count' number of samples and execute a
	* touch detection twice, with 1 sample each
	*/
	priv->expected_samples = priv->sample_count * 2 + 2;
	*items = 6;

	return 0;
	}

	static void mx25_tcq_disable_touch_irq(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK,
	MX25_ADCQ_CR_PDMSK);
	}

	static void mx25_tcq_enable_touch_irq(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_PDMSK, 0);
	}

	static void mx25_tcq_disable_fifo_irq(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ,
	MX25_ADCQ_MR_FDRY_IRQ);
	}

	static void mx25_tcq_enable_fifo_irq(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_FDRY_IRQ, 0);
	}

	static void mx25_tcq_force_queue_start(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_FQS,
	MX25_ADCQ_CR_FQS);
	}

	static void mx25_tcq_force_queue_stop(struct mx25_tcq_priv *priv)
	{
	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_FQS, 0);
	}

	static void mx25_tcq_fifo_reset(struct mx25_tcq_priv *priv)
	{
	u32 tcqcr;

	regmap_read(priv->regs, MX25_ADCQ_CR, &tcqcr);
	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST,
	MX25_ADCQ_CR_FRST);
	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FRST, 0);
	regmap_write(priv->regs, MX25_ADCQ_CR, tcqcr);
	}

	static void mx25_tcq_re_enable_touch_detection(struct mx25_tcq_priv *priv)
	{
	/* stop the queue from looping */
	mx25_tcq_force_queue_stop(priv);

	/* for a clean touch detection, preload the X plane */
	regmap_write(priv->core_regs, MX25_TSC_TICR, MX25_PRECHARGE_VALUE);

	/* waste some time now to pre-load the X plate to high voltage */
	mx25_tcq_fifo_reset(priv);

	/* re-enable the detection right now */
	regmap_write(priv->core_regs, MX25_TSC_TICR,
	MX25_TOUCH_DETECT_VALUE \| MX25_ADCQ_CFG_IGS);

	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_PD,
	MX25_ADCQ_SR_PD);

	/* enable the pen down event to be a source for the interrupt */
	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_PD_IRQ, 0);

	/* lets fire the next IRQ if someone touches the touchscreen */
	mx25_tcq_enable_touch_irq(priv);
	}

	static void mx25_tcq_create_event_for_4wire(struct mx25_tcq_priv *priv,
	u32 *sample_buf,
	unsigned int samples)
	{
	unsigned int x_pos = 0;
	unsigned int y_pos = 0;
	unsigned int touch_pre = 0;
	unsigned int touch_post = 0;
	unsigned int i;

	for (i = 0; i < samples; i++) {
	unsigned int index = MX25_ADCQ_FIFO_ID(sample_buf[i]);
	unsigned int val = MX25_ADCQ_FIFO_DATA(sample_buf[i]);

	switch (index) {
	case 1:
	touch_pre = val;
	break;
	case 2:
	x_pos = val;
	break;
	case 3:
	y_pos = val;
	break;
	case 5:
	touch_post = val;
	break;
	default:
	dev_dbg(priv->dev, "Dropped samples because of invalid index %d\n",
	index);
	return;
	}
	}

	if (samples != 0) {
	/*
	* only if both touch measures are below a threshold,
	* the position is valid
	*/
	if (touch_pre < priv->pen_threshold &&
	touch_post < priv->pen_threshold) {
	/* valid samples, generate a report */
	x_pos /= priv->sample_count;
	y_pos /= priv->sample_count;
	input_report_abs(priv->idev, ABS_X, x_pos);
	input_report_abs(priv->idev, ABS_Y, y_pos);
	input_report_key(priv->idev, BTN_TOUCH, 1);
	input_sync(priv->idev);

	/* get next sample */
	mx25_tcq_enable_fifo_irq(priv);
	} else if (touch_pre >= priv->pen_threshold &&
	touch_post >= priv->pen_threshold) {
	/*
	* if both samples are invalid,
	* generate a release report
	*/
	input_report_key(priv->idev, BTN_TOUCH, 0);
	input_sync(priv->idev);
	mx25_tcq_re_enable_touch_detection(priv);
	} else {
	/*
	* if only one of both touch measurements are
	* below the threshold, still some bouncing
	* happens. Take additional samples in this
	* case to be sure
	*/
	mx25_tcq_enable_fifo_irq(priv);
	}
	}
	}

	static irqreturn_t mx25_tcq_irq_thread(int irq, void *dev_id)
	{
	struct mx25_tcq_priv *priv = dev_id;
	u32 sample_buf[TSC_MAX_SAMPLES];
	unsigned int samples;
	u32 stats;
	unsigned int i;

	/*
	* Check how many samples are available. We always have to read exactly
	* sample_count samples from the fifo, or a multiple of sample_count.
	* Otherwise we mixup samples into different touch events.
	*/
	regmap_read(priv->regs, MX25_ADCQ_SR, &stats);
	samples = MX25_ADCQ_SR_FDN(stats);
	samples -= samples % priv->sample_count;

	if (!samples)
	return IRQ_HANDLED;

	for (i = 0; i != samples; ++i)
	regmap_read(priv->regs, MX25_ADCQ_FIFO, &sample_buf[i]);

	mx25_tcq_create_event_for_4wire(priv, sample_buf, samples);

	return IRQ_HANDLED;
	}

	static irqreturn_t mx25_tcq_irq(int irq, void *dev_id)
	{
	struct mx25_tcq_priv *priv = dev_id;
	u32 stat;
	int ret = IRQ_HANDLED;

	regmap_read(priv->regs, MX25_ADCQ_SR, &stat);

	if (stat & (MX25_ADCQ_SR_FRR \| MX25_ADCQ_SR_FUR \| MX25_ADCQ_SR_FOR))
	mx25_tcq_re_enable_touch_detection(priv);

	if (stat & MX25_ADCQ_SR_PD) {
	mx25_tcq_disable_touch_irq(priv);
	mx25_tcq_force_queue_start(priv);
	mx25_tcq_enable_fifo_irq(priv);
	}

	if (stat & MX25_ADCQ_SR_FDRY) {
	mx25_tcq_disable_fifo_irq(priv);
	ret = IRQ_WAKE_THREAD;
	}

	regmap_update_bits(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_FRR \|
	MX25_ADCQ_SR_FUR \| MX25_ADCQ_SR_FOR \|
	MX25_ADCQ_SR_PD,
	MX25_ADCQ_SR_FRR \| MX25_ADCQ_SR_FUR \|
	MX25_ADCQ_SR_FOR \| MX25_ADCQ_SR_PD);

	return ret;
	}

	/* configure the state machine for a 4-wire touchscreen */
	static int mx25_tcq_init(struct mx25_tcq_priv *priv)
	{
	u32 tgcr;
	unsigned int ipg_div;
	unsigned int adc_period;
	unsigned int debounce_cnt;
	unsigned int settling_cnt;
	int itemct;
	int error;

	regmap_read(priv->core_regs, MX25_TSC_TGCR, &tgcr);
	ipg_div = max_t(unsigned int, 4, MX25_TGCR_GET_ADCCLK(tgcr));
	adc_period = USEC_PER_SEC * ipg_div * 2 + 2;
	adc_period /= clk_get_rate(priv->clk) / 1000 + 1;
	debounce_cnt = DIV_ROUND_UP(priv->pen_debounce, adc_period * 8) - 1;
	settling_cnt = DIV_ROUND_UP(priv->settling_time, adc_period * 8) - 1;

	/* Reset */
	regmap_write(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_QRST \| MX25_ADCQ_CR_FRST);
	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_QRST \| MX25_ADCQ_CR_FRST, 0);

	/* up to 128 * 8 ADC clocks are possible */
	if (debounce_cnt > 127)
	debounce_cnt = 127;

	/* up to 255 * 8 ADC clocks are possible */
	if (settling_cnt > 255)
	settling_cnt = 255;

	error = imx25_setup_queue_4wire(priv, settling_cnt, &itemct);
	if (error)
	return error;

	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_LITEMID_MASK \| MX25_ADCQ_CR_WMRK_MASK,
	MX25_ADCQ_CR_LITEMID(itemct - 1) \|
	MX25_ADCQ_CR_WMRK(priv->expected_samples - 1));

	/* setup debounce count */
	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR,
	MX25_TGCR_PDBTIME_MASK,
	MX25_TGCR_PDBTIME(debounce_cnt));

	/* enable debounce */
	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDBEN,
	MX25_TGCR_PDBEN);
	regmap_update_bits(priv->core_regs, MX25_TSC_TGCR, MX25_TGCR_PDEN,
	MX25_TGCR_PDEN);

	/* enable the engine on demand */
	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_QSM_MASK,
	MX25_ADCQ_CR_QSM_FQS);

	/* Enable repeat and repeat wait */
	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
	MX25_ADCQ_CR_RPT \| MX25_ADCQ_CR_RWAIT_MASK,
	MX25_ADCQ_CR_RPT \|
	MX25_ADCQ_CR_RWAIT(MX25_TSC_REPEAT_WAIT));

	return 0;
	}

	static int mx25_tcq_parse_dt(struct platform_device *pdev,
	struct mx25_tcq_priv *priv)
	{
	struct device_node *np = pdev->dev.of_node;
	u32 wires;
	int error;

	/* Setup defaults */
	priv->pen_threshold = 500;
	priv->sample_count = 3;
	priv->pen_debounce = 1000000;
	priv->settling_time = 250000;

	error = of_property_read_u32(np, "fsl,wires", &wires);
	if (error) {
	dev_err(&pdev->dev, "Failed to find fsl,wires properties\n");
	return error;
	}

	if (wires == 4) {
	priv->mode = MX25_TS_4WIRE;
	} else {
	dev_err(&pdev->dev, "%u-wire mode not supported\n", wires);
	return -EINVAL;
	}

	/* These are optional, we don't care about the return values */
	of_property_read_u32(np, "fsl,pen-threshold", &priv->pen_threshold);
	of_property_read_u32(np, "fsl,settling-time-ns", &priv->settling_time);
	of_property_read_u32(np, "fsl,pen-debounce-ns", &priv->pen_debounce);

	return 0;
	}

	static int mx25_tcq_open(struct input_dev *idev)
	{
	struct device *dev = &idev->dev;
	struct mx25_tcq_priv *priv = dev_get_drvdata(dev);
	int error;

	error = clk_prepare_enable(priv->clk);
	if (error) {
	dev_err(dev, "Failed to enable ipg clock\n");
	return error;
	}

	error = mx25_tcq_init(priv);
	if (error) {
	dev_err(dev, "Failed to init tcq\n");
	clk_disable_unprepare(priv->clk);
	return error;
	}

	mx25_tcq_re_enable_touch_detection(priv);

	return 0;
	}

	static void mx25_tcq_close(struct input_dev *idev)
	{
	struct mx25_tcq_priv *priv = input_get_drvdata(idev);

	mx25_tcq_force_queue_stop(priv);
	mx25_tcq_disable_touch_irq(priv);
	mx25_tcq_disable_fifo_irq(priv);
	clk_disable_unprepare(priv->clk);
	}

	static int mx25_tcq_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct input_dev *idev;
	struct mx25_tcq_priv *priv;
	struct mx25_tsadc *tsadc = dev_get_drvdata(dev->parent);
	void __iomem *mem;
	int error;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;
	priv->dev = dev;

	mem = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(mem))
	return PTR_ERR(mem);

	error = mx25_tcq_parse_dt(pdev, priv);
	if (error)
	return error;

	priv->regs = devm_regmap_init_mmio(dev, mem, &mx25_tcq_regconfig);
	if (IS_ERR(priv->regs)) {
	dev_err(dev, "Failed to initialize regmap\n");
	return PTR_ERR(priv->regs);
	}

	priv->irq = platform_get_irq(pdev, 0);
	if (priv->irq <= 0)
	return priv->irq;

	idev = devm_input_allocate_device(dev);
	if (!idev) {
	dev_err(dev, "Failed to allocate input device\n");
	return -ENOMEM;
	}

	idev->name = mx25_tcq_name;
	input_set_capability(idev, EV_KEY, BTN_TOUCH);
	input_set_abs_params(idev, ABS_X, 0, 0xfff, 0, 0);
	input_set_abs_params(idev, ABS_Y, 0, 0xfff, 0, 0);

	idev->id.bustype = BUS_HOST;
	idev->open = mx25_tcq_open;
	idev->close = mx25_tcq_close;

	priv->idev = idev;
	input_set_drvdata(idev, priv);

	priv->core_regs = tsadc->regs;
	if (!priv->core_regs)
	return -EINVAL;

	priv->clk = tsadc->clk;
	if (!priv->clk)
	return -EINVAL;

	platform_set_drvdata(pdev, priv);

	error = devm_request_threaded_irq(dev, priv->irq, mx25_tcq_irq,
	mx25_tcq_irq_thread, 0, pdev->name,
	priv);
	if (error) {
	dev_err(dev, "Failed requesting IRQ\n");
	return error;
	}

	error = input_register_device(idev);
	if (error) {
	dev_err(dev, "Failed to register input device\n");
	return error;
	}

	return 0;
	}

	static struct platform_driver mx25_tcq_driver = {
	.driver = {
	.name = "mx25-tcq",
	.of_match_table = mx25_tcq_ids,
	},
	.probe = mx25_tcq_probe,
	};
	module_platform_driver(mx25_tcq_driver);

	MODULE_DESCRIPTION("TS input driver for Freescale mx25");
	MODULE_AUTHOR("Markus Pargmann <mpa@pengutronix.de>");
	MODULE_LICENSE("GPL v2");