// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Raspberry Pi Sense HAT joystick driver
 * http://raspberrypi.org
 *
 * Copyright (C) 2015 Raspberry Pi
 * Copyright (C) 2021 Charles Mirabile, Mwesigwa Guma, Joel Savitz
 *
 * Original Author: Serge Schneider
 * Revised for upstream Linux by: Charles Mirabile, Mwesigwa Guma, Joel Savitz
 */

#include <linux/module.h>
#include <linux/input.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/property.h>

#define JOYSTICK_SMB_REG 0xf2

struct sensehat_joystick {
        struct platform_device *pdev;
        struct input_dev *keys_dev;
        unsigned long prev_states;
        struct regmap *regmap;
};

static const unsigned int keymap[] = {
        BTN_DPAD_DOWN, BTN_DPAD_RIGHT, BTN_DPAD_UP, BTN_SELECT, BTN_DPAD_LEFT,
};

static irqreturn_t sensehat_joystick_report(int irq, void *cookie)
{
        struct sensehat_joystick *sensehat_joystick = cookie;
        unsigned long curr_states, changes;
        unsigned int keys;
        int error;
        int i;

        error = regmap_read(sensehat_joystick->regmap, JOYSTICK_SMB_REG, &keys);
        if (error < 0) {
                dev_err(&sensehat_joystick->pdev->dev,
                        "Failed to read joystick state: %d", error);
                return IRQ_NONE;
        }
        curr_states = keys;
        bitmap_xor(&changes, &curr_states, &sensehat_joystick->prev_states,
                   ARRAY_SIZE(keymap));

        for_each_set_bit(i, &changes, ARRAY_SIZE(keymap))
                input_report_key(sensehat_joystick->keys_dev, keymap[i],
                                 curr_states & BIT(i));

        input_sync(sensehat_joystick->keys_dev);
        sensehat_joystick->prev_states = keys;
        return IRQ_HANDLED;
}

static int sensehat_joystick_probe(struct platform_device *pdev)
{
        struct sensehat_joystick *sensehat_joystick;
        int error, i, irq;

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

        sensehat_joystick->pdev = pdev;

        sensehat_joystick->regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!sensehat_joystick->regmap) {
                dev_err(&pdev->dev, "unable to get sensehat regmap");
                return -ENODEV;
        }

        sensehat_joystick->keys_dev = devm_input_allocate_device(&pdev->dev);
        if (!sensehat_joystick->keys_dev) {
                dev_err(&pdev->dev, "Could not allocate input device");
                return -ENOMEM;
        }

        sensehat_joystick->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
        sensehat_joystick->keys_dev->phys = "sensehat-joystick/input0";
        sensehat_joystick->keys_dev->id.bustype = BUS_I2C;

        __set_bit(EV_KEY, sensehat_joystick->keys_dev->evbit);
        __set_bit(EV_REP, sensehat_joystick->keys_dev->evbit);
        for (i = 0; i < ARRAY_SIZE(keymap); i++)
                __set_bit(keymap[i], sensehat_joystick->keys_dev->keybit);

        error = input_register_device(sensehat_joystick->keys_dev);
        if (error) {
                dev_err(&pdev->dev, "Could not register input device");
                return error;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        error = devm_request_threaded_irq(&pdev->dev, irq,
                                          NULL, sensehat_joystick_report,
                                          IRQF_ONESHOT, "keys",
                                          sensehat_joystick);
        if (error) {
                dev_err(&pdev->dev, "IRQ request failed");
                return error;
        }

        return 0;
}

static const struct of_device_id sensehat_joystick_device_id[] = {
        { .compatible = "raspberrypi,sensehat-joystick" },
        {},
};
MODULE_DEVICE_TABLE(of, sensehat_joystick_device_id);

static struct platform_driver sensehat_joystick_driver = {
        .probe = sensehat_joystick_probe,
        .driver = {
                .name = "sensehat-joystick",
                .of_match_table = sensehat_joystick_device_id,
        },
};

module_platform_driver(sensehat_joystick_driver);

MODULE_DESCRIPTION("Raspberry Pi Sense HAT joystick driver");
MODULE_AUTHOR("Charles Mirabile <cmirabil@redhat.com>");
MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
MODULE_LICENSE("GPL");