/*
 * TSC2004/TSC2005 touchscreen driver core
 *
 * Copyright (C) 2006-2010 Nokia Corporation
 * Copyright (C) 2015 QWERTY Embedded Design
 * Copyright (C) 2015 EMAC Inc.
 *
 * Author: Lauri Leukkunen <lauri.leukkunen@nokia.com>
 * based on TSC2301 driver by Klaus K. Pedersen <klaus.k.pedersen@nokia.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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/input/touchscreen.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <linux/of.h>
#include <linux/regulator/consumer.h>
#include <linux/regmap.h>
#include <linux/gpio/consumer.h>
#include "tsc200x-core.h"

/*
 * The touchscreen interface operates as follows:
 *
 * 1) Pen is pressed against the touchscreen.
 * 2) TSC200X performs AD conversion.
 * 3) After the conversion is done TSC200X drives DAV line down.
 * 4) GPIO IRQ is received and tsc200x_irq_thread() is scheduled.
 * 5) tsc200x_irq_thread() queues up a transfer to fetch the x, y, z1, z2
 *    values.
 * 6) tsc200x_irq_thread() reports coordinates to input layer and sets up
 *    tsc200x_penup_timer() to be called after TSC200X_PENUP_TIME_MS (40ms).
 * 7) When the penup timer expires, there have not been touch or DAV interrupts
 *    during the last 40ms which means the pen has been lifted.
 *
 * ESD recovery via a hardware reset is done if the TSC200X doesn't respond
 * after a configurable period (in ms) of activity. If esd_timeout is 0, the
 * watchdog is disabled.
 */

static const struct regmap_range tsc200x_writable_ranges[] = {
        regmap_reg_range(TSC200X_REG_AUX_HIGH, TSC200X_REG_CFR2),
};

static const struct regmap_access_table tsc200x_writable_table = {
        .yes_ranges = tsc200x_writable_ranges,
        .n_yes_ranges = ARRAY_SIZE(tsc200x_writable_ranges),
};

const struct regmap_config tsc200x_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .reg_stride = 0x08,
        .max_register = 0x78,
        .read_flag_mask = TSC200X_REG_READ,
        .write_flag_mask = TSC200X_REG_PND0,
        .wr_table = &tsc200x_writable_table,
        .use_single_rw = true,
};
EXPORT_SYMBOL_GPL(tsc200x_regmap_config);

struct tsc200x_data {
        u16 x;
        u16 y;
        u16 z1;
        u16 z2;
} __packed;
#define TSC200X_DATA_REGS 4

struct tsc200x {
        struct device           *dev;
        struct regmap           *regmap;
        __u16                   bustype;

        struct input_dev        *idev;
        char                    phys[32];

        struct mutex            mutex;

        /* raw copy of previous x,y,z */
        int                     in_x;
        int                     in_y;
        int                     in_z1;
        int                     in_z2;

        spinlock_t              lock;
        struct timer_list       penup_timer;

        unsigned int            esd_timeout;
        struct delayed_work     esd_work;
        unsigned long           last_valid_interrupt;

        unsigned int            x_plate_ohm;

        bool                    opened;
        bool                    suspended;

        bool                    pen_down;

        struct regulator        *vio;

        struct gpio_desc        *reset_gpio;
        int                     (*tsc200x_cmd)(struct device *dev, u8 cmd);
        int                     irq;
};

static void tsc200x_update_pen_state(struct tsc200x *ts,
                                     int x, int y, int pressure)
{
        if (pressure) {
                input_report_abs(ts->idev, ABS_X, x);
                input_report_abs(ts->idev, ABS_Y, y);
                input_report_abs(ts->idev, ABS_PRESSURE, pressure);
                if (!ts->pen_down) {
                        input_report_key(ts->idev, BTN_TOUCH, !!pressure);
                        ts->pen_down = true;
                }
        } else {
                input_report_abs(ts->idev, ABS_PRESSURE, 0);
                if (ts->pen_down) {
                        input_report_key(ts->idev, BTN_TOUCH, 0);
                        ts->pen_down = false;
                }
        }
        input_sync(ts->idev);
        dev_dbg(ts->dev, "point(%4d,%4d), pressure (%4d)\n", x, y,
                pressure);
}

static irqreturn_t tsc200x_irq_thread(int irq, void *_ts)
{
        struct tsc200x *ts = _ts;
        unsigned long flags;
        unsigned int pressure;
        struct tsc200x_data tsdata;
        int error;

        /* read the coordinates */
        error = regmap_bulk_read(ts->regmap, TSC200X_REG_X, &tsdata,
                                 TSC200X_DATA_REGS);
        if (unlikely(error))
                goto out;

        /* validate position */
        if (unlikely(tsdata.x > MAX_12BIT || tsdata.y > MAX_12BIT))
                goto out;

        /* Skip reading if the pressure components are out of range */
        if (unlikely(tsdata.z1 == 0 || tsdata.z2 > MAX_12BIT))
                goto out;
        if (unlikely(tsdata.z1 >= tsdata.z2))
                goto out;

       /*
        * Skip point if this is a pen down with the exact same values as
        * the value before pen-up - that implies SPI fed us stale data
        */
        if (!ts->pen_down &&
            ts->in_x == tsdata.x && ts->in_y == tsdata.y &&
            ts->in_z1 == tsdata.z1 && ts->in_z2 == tsdata.z2) {
                goto out;
        }

        /*
         * At this point we are happy we have a valid and useful reading.
         * Remember it for later comparisons. We may now begin downsampling.
         */
        ts->in_x = tsdata.x;
        ts->in_y = tsdata.y;
        ts->in_z1 = tsdata.z1;
        ts->in_z2 = tsdata.z2;

        /* Compute touch pressure resistance using equation #1 */
        pressure = tsdata.x * (tsdata.z2 - tsdata.z1) / tsdata.z1;
        pressure = pressure * ts->x_plate_ohm / 4096;
        if (unlikely(pressure > MAX_12BIT))
                goto out;

        spin_lock_irqsave(&ts->lock, flags);

        tsc200x_update_pen_state(ts, tsdata.x, tsdata.y, pressure);
        mod_timer(&ts->penup_timer,
                  jiffies + msecs_to_jiffies(TSC200X_PENUP_TIME_MS));

        spin_unlock_irqrestore(&ts->lock, flags);

        ts->last_valid_interrupt = jiffies;
out:
        return IRQ_HANDLED;
}

static void tsc200x_penup_timer(unsigned long data)
{
        struct tsc200x *ts = (struct tsc200x *)data;
        unsigned long flags;

        spin_lock_irqsave(&ts->lock, flags);
        tsc200x_update_pen_state(ts, 0, 0, 0);
        spin_unlock_irqrestore(&ts->lock, flags);
}

static void tsc200x_start_scan(struct tsc200x *ts)
{
        regmap_write(ts->regmap, TSC200X_REG_CFR0, TSC200X_CFR0_INITVALUE);
        regmap_write(ts->regmap, TSC200X_REG_CFR1, TSC200X_CFR1_INITVALUE);
        regmap_write(ts->regmap, TSC200X_REG_CFR2, TSC200X_CFR2_INITVALUE);
        ts->tsc200x_cmd(ts->dev, TSC200X_CMD_NORMAL);
}

static void tsc200x_stop_scan(struct tsc200x *ts)
{
        ts->tsc200x_cmd(ts->dev, TSC200X_CMD_STOP);
}

static void tsc200x_reset(struct tsc200x *ts)
{
        if (ts->reset_gpio) {
                gpiod_set_value_cansleep(ts->reset_gpio, 1);
                usleep_range(100, 500); /* only 10us required */
                gpiod_set_value_cansleep(ts->reset_gpio, 0);
        }
}

/* must be called with ts->mutex held */
static void __tsc200x_disable(struct tsc200x *ts)
{
        tsc200x_stop_scan(ts);

        disable_irq(ts->irq);
        del_timer_sync(&ts->penup_timer);

        cancel_delayed_work_sync(&ts->esd_work);

        enable_irq(ts->irq);
}

/* must be called with ts->mutex held */
static void __tsc200x_enable(struct tsc200x *ts)
{
        tsc200x_start_scan(ts);

        if (ts->esd_timeout && ts->reset_gpio) {
                ts->last_valid_interrupt = jiffies;
                schedule_delayed_work(&ts->esd_work,
                                round_jiffies_relative(
                                        msecs_to_jiffies(ts->esd_timeout)));
        }
}

static ssize_t tsc200x_selftest_show(struct device *dev,
                                     struct device_attribute *attr,
                                     char *buf)
{
        struct tsc200x *ts = dev_get_drvdata(dev);
        unsigned int temp_high;
        unsigned int temp_high_orig;
        unsigned int temp_high_test;
        bool success = true;
        int error;

        mutex_lock(&ts->mutex);

        /*
         * Test TSC200X communications via temp high register.
         */
        __tsc200x_disable(ts);

        error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high_orig);
        if (error) {
                dev_warn(dev, "selftest failed: read error %d\n", error);
                success = false;
                goto out;
        }

        temp_high_test = (temp_high_orig - 1) & MAX_12BIT;

        error = regmap_write(ts->regmap, TSC200X_REG_TEMP_HIGH, temp_high_test);
        if (error) {
                dev_warn(dev, "selftest failed: write error %d\n", error);
                success = false;
                goto out;
        }

        error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
        if (error) {
                dev_warn(dev, "selftest failed: read error %d after write\n",
                         error);
                success = false;
                goto out;
        }

        if (temp_high != temp_high_test) {
                dev_warn(dev, "selftest failed: %d != %d\n",
                         temp_high, temp_high_test);
                success = false;
        }

        /* hardware reset */
        tsc200x_reset(ts);

        if (!success)
                goto out;

        /* test that the reset really happened */
        error = regmap_read(ts->regmap, TSC200X_REG_TEMP_HIGH, &temp_high);
        if (error) {
                dev_warn(dev, "selftest failed: read error %d after reset\n",
                         error);
                success = false;
                goto out;
        }

        if (temp_high != temp_high_orig) {
                dev_warn(dev, "selftest failed after reset: %d != %d\n",
                         temp_high, temp_high_orig);
                success = false;
        }

out:
        __tsc200x_enable(ts);
        mutex_unlock(&ts->mutex);

        return sprintf(buf, "%d\n", success);
}

static DEVICE_ATTR(selftest, S_IRUGO, tsc200x_selftest_show, NULL);

static struct attribute *tsc200x_attrs[] = {
        &dev_attr_selftest.attr,
        NULL
};

static umode_t tsc200x_attr_is_visible(struct kobject *kobj,
                                      struct attribute *attr, int n)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct tsc200x *ts = dev_get_drvdata(dev);
        umode_t mode = attr->mode;

        if (attr == &dev_attr_selftest.attr) {
                if (!ts->reset_gpio)
                        mode = 0;
        }

        return mode;
}

static const struct attribute_group tsc200x_attr_group = {
        .is_visible     = tsc200x_attr_is_visible,
        .attrs          = tsc200x_attrs,
};

static void tsc200x_esd_work(struct work_struct *work)
{
        struct tsc200x *ts = container_of(work, struct tsc200x, esd_work.work);
        int error;
        unsigned int r;

        if (!mutex_trylock(&ts->mutex)) {
                /*
                 * If the mutex is taken, it means that disable or enable is in
                 * progress. In that case just reschedule the work. If the work
                 * is not needed, it will be canceled by disable.
                 */
                goto reschedule;
        }

        if (time_is_after_jiffies(ts->last_valid_interrupt +
                                  msecs_to_jiffies(ts->esd_timeout)))
                goto out;

        /* We should be able to read register without disabling interrupts. */
        error = regmap_read(ts->regmap, TSC200X_REG_CFR0, &r);
        if (!error &&
            !((r ^ TSC200X_CFR0_INITVALUE) & TSC200X_CFR0_RW_MASK)) {
                goto out;
        }

        /*
         * If we could not read our known value from configuration register 0
         * then we should reset the controller as if from power-up and start
         * scanning again.
         */
        dev_info(ts->dev, "TSC200X not responding - resetting\n");

        disable_irq(ts->irq);
        del_timer_sync(&ts->penup_timer);

        tsc200x_update_pen_state(ts, 0, 0, 0);

        tsc200x_reset(ts);

        enable_irq(ts->irq);
        tsc200x_start_scan(ts);

out:
        mutex_unlock(&ts->mutex);
reschedule:
        /* re-arm the watchdog */
        schedule_delayed_work(&ts->esd_work,
                              round_jiffies_relative(
                                        msecs_to_jiffies(ts->esd_timeout)));
}

static int tsc200x_open(struct input_dev *input)
{
        struct tsc200x *ts = input_get_drvdata(input);

        mutex_lock(&ts->mutex);

        if (!ts->suspended)
                __tsc200x_enable(ts);

        ts->opened = true;

        mutex_unlock(&ts->mutex);

        return 0;
}

static void tsc200x_close(struct input_dev *input)
{
        struct tsc200x *ts = input_get_drvdata(input);

        mutex_lock(&ts->mutex);

        if (!ts->suspended)
                __tsc200x_disable(ts);

        ts->opened = false;

        mutex_unlock(&ts->mutex);
}

int tsc200x_probe(struct device *dev, int irq, const struct input_id *tsc_id,
                  struct regmap *regmap,
                  int (*tsc200x_cmd)(struct device *dev, u8 cmd))
{
        struct tsc200x *ts;
        struct input_dev *input_dev;
        u32 x_plate_ohm;
        u32 esd_timeout;
        int error;

        if (irq <= 0) {
                dev_err(dev, "no irq\n");
                return -ENODEV;
        }

        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        if (!tsc200x_cmd) {
                dev_err(dev, "no cmd function\n");
                return -ENODEV;
        }

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

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

        ts->irq = irq;
        ts->dev = dev;
        ts->idev = input_dev;
        ts->regmap = regmap;
        ts->tsc200x_cmd = tsc200x_cmd;

        error = device_property_read_u32(dev, "ti,x-plate-ohms", &x_plate_ohm);
        ts->x_plate_ohm = error ? TSC200X_DEF_RESISTOR : x_plate_ohm;

        error = device_property_read_u32(dev, "ti,esd-recovery-timeout-ms",
                                         &esd_timeout);
        ts->esd_timeout = error ? 0 : esd_timeout;

        ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(ts->reset_gpio)) {
                error = PTR_ERR(ts->reset_gpio);
                dev_err(dev, "error acquiring reset gpio: %d\n", error);
                return error;
        }

        ts->vio = devm_regulator_get(dev, "vio");
        if (IS_ERR(ts->vio)) {
                error = PTR_ERR(ts->vio);
                dev_err(dev, "error acquiring vio regulator: %d", error);
                return error;
        }

        mutex_init(&ts->mutex);

        spin_lock_init(&ts->lock);
        setup_timer(&ts->penup_timer, tsc200x_penup_timer, (unsigned long)ts);

        INIT_DELAYED_WORK(&ts->esd_work, tsc200x_esd_work);

        snprintf(ts->phys, sizeof(ts->phys),
                 "%s/input-ts", dev_name(dev));

        if (tsc_id->product == 2004) {
                input_dev->name = "TSC200X touchscreen";
        } else {
                input_dev->name = devm_kasprintf(dev, GFP_KERNEL,
                                                 "TSC%04d touchscreen",
                                                 tsc_id->product);
                if (!input_dev->name)
                        return -ENOMEM;
        }

        input_dev->phys = ts->phys;
        input_dev->id = *tsc_id;

        input_dev->open = tsc200x_open;
        input_dev->close = tsc200x_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, TSC200X_DEF_X_FUZZ, 0);
        input_set_abs_params(input_dev, ABS_Y,
                             0, MAX_12BIT, TSC200X_DEF_Y_FUZZ, 0);
        input_set_abs_params(input_dev, ABS_PRESSURE,
                             0, MAX_12BIT, TSC200X_DEF_P_FUZZ, 0);

        touchscreen_parse_properties(input_dev, false, NULL);

        /* Ensure the touchscreen is off */
        tsc200x_stop_scan(ts);

        error = devm_request_threaded_irq(dev, irq, NULL,
                                          tsc200x_irq_thread,
                                          IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                                          "tsc200x", ts);
        if (error) {
                dev_err(dev, "Failed to request irq, err: %d\n", error);
                return error;
        }

        error = regulator_enable(ts->vio);
        if (error)
                return error;

        dev_set_drvdata(dev, ts);
        error = sysfs_create_group(&dev->kobj, &tsc200x_attr_group);
        if (error) {
                dev_err(dev,
                        "Failed to create sysfs attributes, err: %d\n", error);
                goto disable_regulator;
        }

        error = input_register_device(ts->idev);
        if (error) {
                dev_err(dev,
                        "Failed to register input device, err: %d\n", error);
                goto err_remove_sysfs;
        }

        irq_set_irq_wake(irq, 1);
        return 0;

err_remove_sysfs:
        sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);
disable_regulator:
        regulator_disable(ts->vio);
        return error;
}
EXPORT_SYMBOL_GPL(tsc200x_probe);

int tsc200x_remove(struct device *dev)
{
        struct tsc200x *ts = dev_get_drvdata(dev);

        sysfs_remove_group(&dev->kobj, &tsc200x_attr_group);

        regulator_disable(ts->vio);

        return 0;
}
EXPORT_SYMBOL_GPL(tsc200x_remove);

static int __maybe_unused tsc200x_suspend(struct device *dev)
{
        struct tsc200x *ts = dev_get_drvdata(dev);

        mutex_lock(&ts->mutex);

        if (!ts->suspended && ts->opened)
                __tsc200x_disable(ts);

        ts->suspended = true;

        mutex_unlock(&ts->mutex);

        return 0;
}

static int __maybe_unused tsc200x_resume(struct device *dev)
{
        struct tsc200x *ts = dev_get_drvdata(dev);

        mutex_lock(&ts->mutex);

        if (ts->suspended && ts->opened)
                __tsc200x_enable(ts);

        ts->suspended = false;

        mutex_unlock(&ts->mutex);

        return 0;
}

SIMPLE_DEV_PM_OPS(tsc200x_pm_ops, tsc200x_suspend, tsc200x_resume);
EXPORT_SYMBOL_GPL(tsc200x_pm_ops);

MODULE_AUTHOR("Lauri Leukkunen <lauri.leukkunen@nokia.com>");
MODULE_DESCRIPTION("TSC200x Touchscreen Driver Core");
MODULE_LICENSE("GPL");