// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Elan touchscreens that use the i2c-hid protocol.
 *
 * Copyright 2020 Google LLC
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/hid.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/regulator/consumer.h>

#include "i2c-hid.h"

struct elan_i2c_hid_chip_data {
        unsigned int post_gpio_reset_on_delay_ms;
        unsigned int post_gpio_reset_off_delay_ms;
        unsigned int post_power_delay_ms;
        u16 hid_descriptor_address;
        const char *main_supply_name;
        bool power_after_backlight;
};

struct i2c_hid_of_elan {
        struct i2chid_ops ops;

        struct regulator *vcc33;
        struct regulator *vccio;
        struct gpio_desc *reset_gpio;
        bool no_reset_on_power_off;
        const struct elan_i2c_hid_chip_data *chip_data;
};

static int elan_i2c_hid_power_up(struct i2chid_ops *ops)
{
        struct i2c_hid_of_elan *ihid_elan =
                container_of(ops, struct i2c_hid_of_elan, ops);
        int ret;

        gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);

        if (ihid_elan->vcc33) {
                ret = regulator_enable(ihid_elan->vcc33);
                if (ret)
                        goto err_deassert_reset;
        }

        ret = regulator_enable(ihid_elan->vccio);
        if (ret)
                goto err_disable_vcc33;

        if (ihid_elan->chip_data->post_power_delay_ms)
                msleep(ihid_elan->chip_data->post_power_delay_ms);

        gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);
        if (ihid_elan->chip_data->post_gpio_reset_on_delay_ms)
                msleep(ihid_elan->chip_data->post_gpio_reset_on_delay_ms);

        return 0;

err_disable_vcc33:
        if (ihid_elan->vcc33)
                regulator_disable(ihid_elan->vcc33);
err_deassert_reset:
        if (ihid_elan->no_reset_on_power_off)
                gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);

        return ret;
}

static void elan_i2c_hid_power_down(struct i2chid_ops *ops)
{
        struct i2c_hid_of_elan *ihid_elan =
                container_of(ops, struct i2c_hid_of_elan, ops);

        /*
         * Do not assert reset when the hardware allows for it to remain
         * deasserted regardless of the state of the (shared) power supply to
         * avoid wasting power when the supply is left on.
         */
        if (!ihid_elan->no_reset_on_power_off)
                gpiod_set_value_cansleep(ihid_elan->reset_gpio, 1);

        if (ihid_elan->chip_data->post_gpio_reset_off_delay_ms)
                msleep(ihid_elan->chip_data->post_gpio_reset_off_delay_ms);

        regulator_disable(ihid_elan->vccio);
        if (ihid_elan->vcc33)
                regulator_disable(ihid_elan->vcc33);
}

static int i2c_hid_of_elan_probe(struct i2c_client *client)
{
        struct i2c_hid_of_elan *ihid_elan;
        int ret;
        u32 quirks = 0;

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

        ihid_elan->ops.power_up = elan_i2c_hid_power_up;
        ihid_elan->ops.power_down = elan_i2c_hid_power_down;

        /* Start out with reset asserted */
        ihid_elan->reset_gpio =
                devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(ihid_elan->reset_gpio))
                return PTR_ERR(ihid_elan->reset_gpio);

        ihid_elan->no_reset_on_power_off = of_property_read_bool(client->dev.of_node,
                                                "no-reset-on-power-off");

        ihid_elan->vccio = devm_regulator_get(&client->dev, "vccio");
        if (IS_ERR(ihid_elan->vccio)) {
                ret = PTR_ERR(ihid_elan->vccio);
                goto err_deassert_reset;
        }

        ihid_elan->chip_data = device_get_match_data(&client->dev);

        if (ihid_elan->chip_data->main_supply_name) {
                ihid_elan->vcc33 = devm_regulator_get(&client->dev,
                                                      ihid_elan->chip_data->main_supply_name);
                if (IS_ERR(ihid_elan->vcc33)) {
                        ret = PTR_ERR(ihid_elan->vcc33);
                        goto err_deassert_reset;
                }
        }

        if (ihid_elan->chip_data->power_after_backlight)
                quirks = HID_QUIRK_POWER_ON_AFTER_BACKLIGHT;

        ret = i2c_hid_core_probe(client, &ihid_elan->ops,
                                 ihid_elan->chip_data->hid_descriptor_address,
                                 quirks);
        if (ret)
                goto err_deassert_reset;

        return 0;

err_deassert_reset:
        if (ihid_elan->no_reset_on_power_off)
                gpiod_set_value_cansleep(ihid_elan->reset_gpio, 0);

        return ret;
}

static const struct elan_i2c_hid_chip_data elan_ekth6915_chip_data = {
        .post_power_delay_ms = 1,
        .post_gpio_reset_on_delay_ms = 300,
        .hid_descriptor_address = 0x0001,
        .main_supply_name = "vcc33",
        .power_after_backlight = true,
};

static const struct elan_i2c_hid_chip_data elan_ekth6a12nay_chip_data = {
        .post_power_delay_ms = 10,
        .post_gpio_reset_on_delay_ms = 300,
        .hid_descriptor_address = 0x0001,
        .main_supply_name = "vcc33",
        .power_after_backlight = true,
};

static const struct elan_i2c_hid_chip_data focaltech_ft8112_chip_data = {
        .post_power_delay_ms = 10,
        .post_gpio_reset_on_delay_ms = 150,
        .hid_descriptor_address = 0x0001,
        .main_supply_name = "vcc33",
};

static const struct elan_i2c_hid_chip_data ilitek_ili9882t_chip_data = {
        .post_power_delay_ms = 1,
        .post_gpio_reset_on_delay_ms = 200,
        .post_gpio_reset_off_delay_ms = 65,
        .hid_descriptor_address = 0x0001,
        /*
         * this touchscreen is tightly integrated with the panel and assumes
         * that the relevant power rails (other than the IO rail) have already
         * been turned on by the panel driver because we're a panel follower.
         */
        .main_supply_name = NULL,
};

static const struct elan_i2c_hid_chip_data ilitek_ili2901_chip_data = {
        .post_power_delay_ms = 10,
        .post_gpio_reset_on_delay_ms = 100,
        .hid_descriptor_address = 0x0001,
        .main_supply_name = "vcc33",
};

static const struct of_device_id elan_i2c_hid_of_match[] = {
        { .compatible = "elan,ekth6915", .data = &elan_ekth6915_chip_data },
        { .compatible = "elan,ekth6a12nay", .data = &elan_ekth6a12nay_chip_data },
        { .compatible = "focaltech,ft8112", .data = &focaltech_ft8112_chip_data },
        { .compatible = "ilitek,ili9882t", .data = &ilitek_ili9882t_chip_data },
        { .compatible = "ilitek,ili2901", .data = &ilitek_ili2901_chip_data },
        { }
};
MODULE_DEVICE_TABLE(of, elan_i2c_hid_of_match);

static struct i2c_driver elan_i2c_hid_ts_driver = {
        .driver = {
                .name   = "i2c_hid_of_elan",
                .pm     = &i2c_hid_core_pm,
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_match_ptr(elan_i2c_hid_of_match),
        },
        .probe          = i2c_hid_of_elan_probe,
        .remove         = i2c_hid_core_remove,
        .shutdown       = i2c_hid_core_shutdown,
};
module_i2c_driver(elan_i2c_hid_ts_driver);

MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>");
MODULE_DESCRIPTION("Elan i2c-hid touchscreen driver");
MODULE_LICENSE("GPL");