// 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 const struct regmap_config mx25_tcq_regconfig = {
        .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");