/*
 * Touchscreen driver for the TS-4800 board
 *
 * Copyright (c) 2015 - Savoir-faire Linux
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/bitops.h>
#include <linux/input.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

/* polling interval in ms */
#define POLL_INTERVAL           3

#define DEBOUNCE_COUNT          1

/* sensor values are 12-bit wide */
#define MAX_12BIT               ((1 << 12) - 1)

#define PENDOWN_MASK            0x1

#define X_OFFSET                0x0
#define Y_OFFSET                0x2

struct ts4800_ts {
        struct input_dev        *input;
        struct device           *dev;
        char                    phys[32];

        void __iomem            *base;
        struct regmap           *regmap;
        unsigned int            reg;
        unsigned int            bit;

        bool                    pendown;
        int                     debounce;
};

static int ts4800_ts_open(struct input_dev *input_dev)
{
        struct ts4800_ts *ts = input_get_drvdata(input_dev);
        int error;

        ts->pendown = false;
        ts->debounce = DEBOUNCE_COUNT;

        error = regmap_update_bits(ts->regmap, ts->reg, ts->bit, ts->bit);
        if (error) {
                dev_warn(ts->dev, "Failed to enable touchscreen: %d\n", error);
                return error;
        }

        return 0;
}

static void ts4800_ts_close(struct input_dev *input_dev)
{
        struct ts4800_ts *ts = input_get_drvdata(input_dev);
        int ret;

        ret = regmap_update_bits(ts->regmap, ts->reg, ts->bit, 0);
        if (ret)
                dev_warn(ts->dev, "Failed to disable touchscreen\n");

}

static void ts4800_ts_poll(struct input_dev *input_dev)
{
        struct ts4800_ts *ts = input_get_drvdata(input_dev);
        u16 last_x = readw(ts->base + X_OFFSET);
        u16 last_y = readw(ts->base + Y_OFFSET);
        bool pendown = last_x & PENDOWN_MASK;

        if (pendown) {
                if (ts->debounce) {
                        ts->debounce--;
                        return;
                }

                if (!ts->pendown) {
                        input_report_key(input_dev, BTN_TOUCH, 1);
                        ts->pendown = true;
                }

                last_x = ((~last_x) >> 4) & MAX_12BIT;
                last_y = ((~last_y) >> 4) & MAX_12BIT;

                input_report_abs(input_dev, ABS_X, last_x);
                input_report_abs(input_dev, ABS_Y, last_y);
                input_sync(input_dev);
        } else if (ts->pendown) {
                ts->pendown = false;
                ts->debounce = DEBOUNCE_COUNT;
                input_report_key(input_dev, BTN_TOUCH, 0);
                input_sync(input_dev);
        }
}

static int ts4800_parse_dt(struct platform_device *pdev,
                           struct ts4800_ts *ts)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        u32 reg, bit;
        int error;

        struct device_node *syscon_np __free(device_node) =
                of_parse_phandle(np, "syscon", 0);
        if (!syscon_np) {
                dev_err(dev, "no syscon property\n");
                return -ENODEV;
        }

        ts->regmap = syscon_node_to_regmap(syscon_np);
        if (IS_ERR(ts->regmap)) {
                dev_err(dev, "cannot get parent's regmap\n");
                return PTR_ERR(ts->regmap);
        }

        error = of_property_read_u32_index(np, "syscon", 1, &reg);
        if (error < 0) {
                dev_err(dev, "no offset in syscon\n");
                return error;
        }

        ts->reg = reg;

        error = of_property_read_u32_index(np, "syscon", 2, &bit);
        if (error < 0) {
                dev_err(dev, "no bit in syscon\n");
                return error;
        }

        ts->bit = BIT(bit);

        return 0;
}

static int ts4800_ts_probe(struct platform_device *pdev)
{
        struct input_dev *input_dev;
        struct ts4800_ts *ts;
        int error;

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

        error = ts4800_parse_dt(pdev, ts);
        if (error)
                return error;

        ts->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(ts->base))
                return PTR_ERR(ts->base);

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

        snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&pdev->dev));
        ts->input = input_dev;
        ts->dev = &pdev->dev;

        input_set_drvdata(input_dev, ts);

        input_dev->name = "TS-4800 Touchscreen";
        input_dev->phys = ts->phys;

        input_dev->open = ts4800_ts_open;
        input_dev->close = ts4800_ts_close;

        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);

        error = input_setup_polling(input_dev, ts4800_ts_poll);
        if (error) {
                dev_err(&pdev->dev, "Unable to set up polling: %d\n", error);
                return error;
        }

        input_set_poll_interval(input_dev, POLL_INTERVAL);

        error = input_register_device(input_dev);
        if (error) {
                dev_err(&pdev->dev,
                        "Unable to register input device: %d\n", error);
                return error;
        }

        return 0;
}

static const struct of_device_id ts4800_ts_of_match[] = {
        { .compatible = "technologic,ts4800-ts", },
        { },
};
MODULE_DEVICE_TABLE(of, ts4800_ts_of_match);

static struct platform_driver ts4800_ts_driver = {
        .driver = {
                .name = "ts4800-ts",
                .of_match_table = ts4800_ts_of_match,
        },
        .probe = ts4800_ts_probe,
};
module_platform_driver(ts4800_ts_driver);

MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
MODULE_DESCRIPTION("TS-4800 Touchscreen Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:ts4800_ts");