// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * AD7879/AD7889 based touchscreen and GPIO driver
 *
 * Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
 *
 * History:
 * Copyright (c) 2005 David Brownell
 * Copyright (c) 2006 Nokia Corporation
 * Various changes: Imre Deak <imre.deak@nokia.com>
 *
 * Using code from:
 *  - corgi_ts.c
 *      Copyright (C) 2004-2005 Richard Purdie
 *  - omap_ts.[hc], ads7846.h, ts_osk.c
 *      Copyright (C) 2002 MontaVista Software
 *      Copyright (C) 2004 Texas Instruments
 *      Copyright (C) 2005 Dirk Behme
 *  - ad7877.c
 *      Copyright (C) 2006-2008 Analog Devices Inc.
 */

#include <linux/device.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/gpio/driver.h>

#include <linux/input/touchscreen.h>
#include <linux/module.h>
#include "ad7879.h"

#define AD7879_REG_ZEROS                0
#define AD7879_REG_CTRL1                1
#define AD7879_REG_CTRL2                2
#define AD7879_REG_CTRL3                3
#define AD7879_REG_AUX1HIGH             4
#define AD7879_REG_AUX1LOW              5
#define AD7879_REG_TEMP1HIGH            6
#define AD7879_REG_TEMP1LOW             7
#define AD7879_REG_XPLUS                8
#define AD7879_REG_YPLUS                9
#define AD7879_REG_Z1                   10
#define AD7879_REG_Z2                   11
#define AD7879_REG_AUXVBAT              12
#define AD7879_REG_TEMP                 13
#define AD7879_REG_REVID                14

/* Control REG 1 */
#define AD7879_TMR(x)                   ((x & 0xFF) << 0)
#define AD7879_ACQ(x)                   ((x & 0x3) << 8)
#define AD7879_MODE_NOC                 (0 << 10)       /* Do not convert */
#define AD7879_MODE_SCC                 (1 << 10)       /* Single channel conversion */
#define AD7879_MODE_SEQ0                (2 << 10)       /* Sequence 0 in Slave Mode */
#define AD7879_MODE_SEQ1                (3 << 10)       /* Sequence 1 in Master Mode */
#define AD7879_MODE_INT                 (1 << 15)       /* PENIRQ disabled INT enabled */

/* Control REG 2 */
#define AD7879_FCD(x)                   ((x & 0x3) << 0)
#define AD7879_RESET                    (1 << 4)
#define AD7879_MFS(x)                   ((x & 0x3) << 5)
#define AD7879_AVG(x)                   ((x & 0x3) << 7)
#define AD7879_SER                      (1 << 9)        /* non-differential */
#define AD7879_DFR                      (0 << 9)        /* differential */
#define AD7879_GPIOPOL                  (1 << 10)
#define AD7879_GPIODIR                  (1 << 11)
#define AD7879_GPIO_DATA                (1 << 12)
#define AD7879_GPIO_EN                  (1 << 13)
#define AD7879_PM(x)                    ((x & 0x3) << 14)
#define AD7879_PM_SHUTDOWN              (0)
#define AD7879_PM_DYN                   (1)
#define AD7879_PM_FULLON                (2)

/* Control REG 3 */
#define AD7879_TEMPMASK_BIT             (1<<15)
#define AD7879_AUXVBATMASK_BIT          (1<<14)
#define AD7879_INTMODE_BIT              (1<<13)
#define AD7879_GPIOALERTMASK_BIT        (1<<12)
#define AD7879_AUXLOW_BIT               (1<<11)
#define AD7879_AUXHIGH_BIT              (1<<10)
#define AD7879_TEMPLOW_BIT              (1<<9)
#define AD7879_TEMPHIGH_BIT             (1<<8)
#define AD7879_YPLUS_BIT                (1<<7)
#define AD7879_XPLUS_BIT                (1<<6)
#define AD7879_Z1_BIT                   (1<<5)
#define AD7879_Z2_BIT                   (1<<4)
#define AD7879_AUX_BIT                  (1<<3)
#define AD7879_VBAT_BIT                 (1<<2)
#define AD7879_TEMP_BIT                 (1<<1)

enum {
        AD7879_SEQ_YPOS  = 0,
        AD7879_SEQ_XPOS  = 1,
        AD7879_SEQ_Z1    = 2,
        AD7879_SEQ_Z2    = 3,
        AD7879_NR_SENSE  = 4,
};

#define MAX_12BIT                       ((1<<12)-1)
#define TS_PEN_UP_TIMEOUT               msecs_to_jiffies(50)

struct ad7879 {
        struct regmap           *regmap;
        struct device           *dev;
        struct input_dev        *input;
        struct timer_list       timer;
#ifdef CONFIG_GPIOLIB
        struct gpio_chip        gc;
        struct mutex            mutex;
#endif
        unsigned int            irq;
        bool                    disabled;       /* P: input->mutex */
        bool                    suspended;      /* P: input->mutex */
        bool                    swap_xy;
        u16                     conversion_data[AD7879_NR_SENSE];
        char                    phys[32];
        u8                      first_conversion_delay;
        u8                      acquisition_time;
        u8                      averaging;
        u8                      pen_down_acc_interval;
        u8                      median;
        u16                     x_plate_ohms;
        u16                     cmd_crtl1;
        u16                     cmd_crtl2;
        u16                     cmd_crtl3;
        int                     x;
        int                     y;
        int                     Rt;
};

static int ad7879_read(struct ad7879 *ts, u8 reg)
{
        unsigned int val;
        int error;

        error = regmap_read(ts->regmap, reg, &val);
        if (error) {
                dev_err(ts->dev, "failed to read register %#02x: %d\n",
                        reg, error);
                return error;
        }

        return val;
}

static int ad7879_write(struct ad7879 *ts, u8 reg, u16 val)
{
        int error;

        error = regmap_write(ts->regmap, reg, val);
        if (error) {
                dev_err(ts->dev,
                        "failed to write %#04x to register %#02x: %d\n",
                        val, reg, error);
                return error;
        }

        return 0;
}

static int ad7879_report(struct ad7879 *ts)
{
        struct input_dev *input_dev = ts->input;
        unsigned Rt;
        u16 x, y, z1, z2;

        x = ts->conversion_data[AD7879_SEQ_XPOS] & MAX_12BIT;
        y = ts->conversion_data[AD7879_SEQ_YPOS] & MAX_12BIT;
        z1 = ts->conversion_data[AD7879_SEQ_Z1] & MAX_12BIT;
        z2 = ts->conversion_data[AD7879_SEQ_Z2] & MAX_12BIT;

        if (ts->swap_xy)
                swap(x, y);

        /*
         * The samples processed here are already preprocessed by the AD7879.
         * The preprocessing function consists of a median and an averaging
         * filter.  The combination of these two techniques provides a robust
         * solution, discarding the spurious noise in the signal and keeping
         * only the data of interest.  The size of both filters is
         * programmable. (dev.platform_data, see linux/platform_data/ad7879.h)
         * Other user-programmable conversion controls include variable
         * acquisition time, and first conversion delay. Up to 16 averages can
         * be taken per conversion.
         */

        if (likely(x && z1)) {
                /* compute touch pressure resistance using equation #1 */
                Rt = (z2 - z1) * x * ts->x_plate_ohms;
                Rt /= z1;
                Rt = (Rt + 2047) >> 12;

                /*
                 * Sample found inconsistent, pressure is beyond
                 * the maximum. Don't report it to user space.
                 */
                if (Rt > input_abs_get_max(input_dev, ABS_PRESSURE))
                        return -EINVAL;

                /*
                 * Note that we delay reporting events by one sample.
                 * This is done to avoid reporting last sample of the
                 * touch sequence, which may be incomplete if finger
                 * leaves the surface before last reading is taken.
                 */
                if (timer_pending(&ts->timer)) {
                        /* Touch continues */
                        input_report_key(input_dev, BTN_TOUCH, 1);
                        input_report_abs(input_dev, ABS_X, ts->x);
                        input_report_abs(input_dev, ABS_Y, ts->y);
                        input_report_abs(input_dev, ABS_PRESSURE, ts->Rt);
                        input_sync(input_dev);
                }

                ts->x = x;
                ts->y = y;
                ts->Rt = Rt;

                return 0;
        }

        return -EINVAL;
}

static void ad7879_ts_event_release(struct ad7879 *ts)
{
        struct input_dev *input_dev = ts->input;

        input_report_abs(input_dev, ABS_PRESSURE, 0);
        input_report_key(input_dev, BTN_TOUCH, 0);
        input_sync(input_dev);
}

static void ad7879_timer(struct timer_list *t)
{
        struct ad7879 *ts = timer_container_of(ts, t, timer);

        ad7879_ts_event_release(ts);
}

static irqreturn_t ad7879_irq(int irq, void *handle)
{
        struct ad7879 *ts = handle;
        int error;

        error = regmap_bulk_read(ts->regmap, AD7879_REG_XPLUS,
                                 ts->conversion_data, AD7879_NR_SENSE);
        if (error)
                dev_err_ratelimited(ts->dev, "failed to read %#02x: %d\n",
                                    AD7879_REG_XPLUS, error);
        else if (!ad7879_report(ts))
                mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);

        return IRQ_HANDLED;
}

static void __ad7879_enable(struct ad7879 *ts)
{
        ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
        ad7879_write(ts, AD7879_REG_CTRL3, ts->cmd_crtl3);
        ad7879_write(ts, AD7879_REG_CTRL1, ts->cmd_crtl1);

        enable_irq(ts->irq);
}

static void __ad7879_disable(struct ad7879 *ts)
{
        u16 reg = (ts->cmd_crtl2 & ~AD7879_PM(-1)) |
                AD7879_PM(AD7879_PM_SHUTDOWN);
        disable_irq(ts->irq);

        if (timer_delete_sync(&ts->timer))
                ad7879_ts_event_release(ts);

        ad7879_write(ts, AD7879_REG_CTRL2, reg);
}


static int ad7879_open(struct input_dev *input)
{
        struct ad7879 *ts = input_get_drvdata(input);

        /* protected by input->mutex */
        if (!ts->disabled && !ts->suspended)
                __ad7879_enable(ts);

        return 0;
}

static void ad7879_close(struct input_dev *input)
{
        struct ad7879 *ts = input_get_drvdata(input);

        /* protected by input->mutex */
        if (!ts->disabled && !ts->suspended)
                __ad7879_disable(ts);
}

static int __maybe_unused ad7879_suspend(struct device *dev)
{
        struct ad7879 *ts = dev_get_drvdata(dev);

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

        if (!ts->suspended && !ts->disabled && input_device_enabled(ts->input))
                __ad7879_disable(ts);

        ts->suspended = true;

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

        return 0;
}

static int __maybe_unused ad7879_resume(struct device *dev)
{
        struct ad7879 *ts = dev_get_drvdata(dev);

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

        if (ts->suspended && !ts->disabled && input_device_enabled(ts->input))
                __ad7879_enable(ts);

        ts->suspended = false;

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

        return 0;
}

SIMPLE_DEV_PM_OPS(ad7879_pm_ops, ad7879_suspend, ad7879_resume);
EXPORT_SYMBOL(ad7879_pm_ops);

static void ad7879_toggle(struct ad7879 *ts, bool disable)
{
        mutex_lock(&ts->input->mutex);

        if (!ts->suspended && input_device_enabled(ts->input)) {

                if (disable) {
                        if (ts->disabled)
                                __ad7879_enable(ts);
                } else {
                        if (!ts->disabled)
                                __ad7879_disable(ts);
                }
        }

        ts->disabled = disable;

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

static ssize_t ad7879_disable_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct ad7879 *ts = dev_get_drvdata(dev);

        return sprintf(buf, "%u\n", ts->disabled);
}

static ssize_t ad7879_disable_store(struct device *dev,
                                     struct device_attribute *attr,
                                     const char *buf, size_t count)
{
        struct ad7879 *ts = dev_get_drvdata(dev);
        unsigned int val;
        int error;

        error = kstrtouint(buf, 10, &val);
        if (error)
                return error;

        ad7879_toggle(ts, val);

        return count;
}

static DEVICE_ATTR(disable, 0664, ad7879_disable_show, ad7879_disable_store);

static struct attribute *ad7879_attributes[] = {
        &dev_attr_disable.attr,
        NULL
};

static const struct attribute_group ad7879_attr_group = {
        .attrs = ad7879_attributes,
};

const struct attribute_group *ad7879_groups[] = {
        &ad7879_attr_group,
        NULL
};
EXPORT_SYMBOL_GPL(ad7879_groups);

#ifdef CONFIG_GPIOLIB
static int ad7879_gpio_direction_input(struct gpio_chip *chip,
                                        unsigned gpio)
{
        struct ad7879 *ts = gpiochip_get_data(chip);
        int err;

        mutex_lock(&ts->mutex);
        ts->cmd_crtl2 |= AD7879_GPIO_EN | AD7879_GPIODIR | AD7879_GPIOPOL;
        err = ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
        mutex_unlock(&ts->mutex);

        return err;
}

static int ad7879_gpio_direction_output(struct gpio_chip *chip,
                                        unsigned gpio, int level)
{
        struct ad7879 *ts = gpiochip_get_data(chip);
        int err;

        mutex_lock(&ts->mutex);
        ts->cmd_crtl2 &= ~AD7879_GPIODIR;
        ts->cmd_crtl2 |= AD7879_GPIO_EN | AD7879_GPIOPOL;
        if (level)
                ts->cmd_crtl2 |= AD7879_GPIO_DATA;
        else
                ts->cmd_crtl2 &= ~AD7879_GPIO_DATA;

        err = ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
        mutex_unlock(&ts->mutex);

        return err;
}

static int ad7879_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
{
        struct ad7879 *ts = gpiochip_get_data(chip);
        u16 val;

        mutex_lock(&ts->mutex);
        val = ad7879_read(ts, AD7879_REG_CTRL2);
        mutex_unlock(&ts->mutex);

        return !!(val & AD7879_GPIO_DATA);
}

static int ad7879_gpio_set_value(struct gpio_chip *chip, unsigned int gpio,
                                 int value)
{
        struct ad7879 *ts = gpiochip_get_data(chip);
        int ret;

        mutex_lock(&ts->mutex);
        if (value)
                ts->cmd_crtl2 |= AD7879_GPIO_DATA;
        else
                ts->cmd_crtl2 &= ~AD7879_GPIO_DATA;

        ret = ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
        mutex_unlock(&ts->mutex);

        return ret;
}

static int ad7879_gpio_add(struct ad7879 *ts)
{
        int ret = 0;

        mutex_init(&ts->mutex);

        /* Do not create a chip unless flagged for it */
        if (!device_property_read_bool(ts->dev, "gpio-controller"))
                return 0;

        ts->gc.direction_input = ad7879_gpio_direction_input;
        ts->gc.direction_output = ad7879_gpio_direction_output;
        ts->gc.get = ad7879_gpio_get_value;
        ts->gc.set = ad7879_gpio_set_value;
        ts->gc.can_sleep = 1;
        ts->gc.base = -1;
        ts->gc.ngpio = 1;
        ts->gc.label = "AD7879-GPIO";
        ts->gc.owner = THIS_MODULE;
        ts->gc.parent = ts->dev;

        ret = devm_gpiochip_add_data(ts->dev, &ts->gc, ts);
        if (ret)
                dev_err(ts->dev, "failed to register gpio %d\n",
                        ts->gc.base);

        return ret;
}
#else
static int ad7879_gpio_add(struct ad7879 *ts)
{
        return 0;
}
#endif

static int ad7879_parse_dt(struct device *dev, struct ad7879 *ts)
{
        int err;
        u32 tmp;

        err = device_property_read_u32(dev, "adi,resistance-plate-x", &tmp);
        if (err) {
                dev_err(dev, "failed to get resistance-plate-x property\n");
                return err;
        }
        ts->x_plate_ohms = (u16)tmp;

        device_property_read_u8(dev, "adi,first-conversion-delay",
                                &ts->first_conversion_delay);
        device_property_read_u8(dev, "adi,acquisition-time",
                                &ts->acquisition_time);
        device_property_read_u8(dev, "adi,median-filter-size", &ts->median);
        device_property_read_u8(dev, "adi,averaging", &ts->averaging);
        device_property_read_u8(dev, "adi,conversion-interval",
                                &ts->pen_down_acc_interval);

        ts->swap_xy = device_property_read_bool(dev, "touchscreen-swapped-x-y");

        return 0;
}

int ad7879_probe(struct device *dev, struct regmap *regmap,
                 int irq, u16 bustype, u8 devid)
{
        struct ad7879 *ts;
        struct input_dev *input_dev;
        int err;
        u16 revid;

        if (irq <= 0) {
                dev_err(dev, "No IRQ specified\n");
                return -EINVAL;
        }

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

        err = ad7879_parse_dt(dev, ts);
        if (err)
                return err;

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

        ts->dev = dev;
        ts->input = input_dev;
        ts->irq = irq;
        ts->regmap = regmap;

        timer_setup(&ts->timer, ad7879_timer, 0);
        snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));

        input_dev->name = "AD7879 Touchscreen";
        input_dev->phys = ts->phys;
        input_dev->dev.parent = dev;
        input_dev->id.bustype = bustype;

        input_dev->open = ad7879_open;
        input_dev->close = ad7879_close;

        input_set_drvdata(input_dev, ts);

        input_set_capability(input_dev, EV_KEY, 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_capability(input_dev, EV_ABS, ABS_PRESSURE);
        touchscreen_parse_properties(input_dev, false, NULL);
        if (!input_abs_get_max(input_dev, ABS_PRESSURE)) {
                dev_err(dev, "Touchscreen pressure is not specified\n");
                return -EINVAL;
        }

        err = ad7879_write(ts, AD7879_REG_CTRL2, AD7879_RESET);
        if (err < 0) {
                dev_err(dev, "Failed to write %s\n", input_dev->name);
                return err;
        }

        revid = ad7879_read(ts, AD7879_REG_REVID);
        input_dev->id.product = (revid & 0xff);
        input_dev->id.version = revid >> 8;
        if (input_dev->id.product != devid) {
                dev_err(dev, "Failed to probe %s (%x vs %x)\n",
                        input_dev->name, devid, revid);
                return -ENODEV;
        }

        ts->cmd_crtl3 = AD7879_YPLUS_BIT |
                        AD7879_XPLUS_BIT |
                        AD7879_Z2_BIT |
                        AD7879_Z1_BIT |
                        AD7879_TEMPMASK_BIT |
                        AD7879_AUXVBATMASK_BIT |
                        AD7879_GPIOALERTMASK_BIT;

        ts->cmd_crtl2 = AD7879_PM(AD7879_PM_DYN) | AD7879_DFR |
                        AD7879_AVG(ts->averaging) |
                        AD7879_MFS(ts->median) |
                        AD7879_FCD(ts->first_conversion_delay);

        ts->cmd_crtl1 = AD7879_MODE_INT | AD7879_MODE_SEQ1 |
                        AD7879_ACQ(ts->acquisition_time) |
                        AD7879_TMR(ts->pen_down_acc_interval);

        err = devm_request_threaded_irq(dev, ts->irq, NULL, ad7879_irq,
                                        IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                        dev_name(dev), ts);
        if (err) {
                dev_err(dev, "Failed to request IRQ: %d\n", err);
                return err;
        }

        __ad7879_disable(ts);

        err = ad7879_gpio_add(ts);
        if (err)
                return err;

        err = input_register_device(input_dev);
        if (err)
                return err;

        dev_set_drvdata(dev, ts);

        return 0;
}
EXPORT_SYMBOL(ad7879_probe);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("AD7879(-1) touchscreen Driver");
MODULE_LICENSE("GPL");