// SPDX-License-Identifier: GPL-2.0-only
/*
 * extcon_gpio.c - Single-state GPIO extcon driver based on extcon class
 *
 * Copyright (C) 2008 Google, Inc.
 * Author: Mike Lockwood <lockwood@android.com>
 *
 * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
 * (originally switch class is supported)
 */

#include <linux/devm-helpers.h>
#include <linux/extcon-provider.h>
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

/**
 * struct gpio_extcon_data - A simple GPIO-controlled extcon device state container.
 * @edev:               Extcon device.
 * @work:               Work fired by the interrupt.
 * @debounce_jiffies:   Number of jiffies to wait for the GPIO to stabilize, from the debounce
 *                      value.
 * @gpiod:              GPIO descriptor for this external connector.
 * @extcon_id:          The unique id of specific external connector.
 * @debounce:           Debounce time for GPIO IRQ in ms.
 * @check_on_resume:    Boolean describing whether to check the state of gpio
 *                      while resuming from sleep.
 */
struct gpio_extcon_data {
        struct extcon_dev *edev;
        struct delayed_work work;
        unsigned long debounce_jiffies;
        struct gpio_desc *gpiod;
        unsigned int extcon_id;
        unsigned long debounce;
        bool check_on_resume;
};

static void gpio_extcon_work(struct work_struct *work)
{
        int state;
        struct gpio_extcon_data *data =
                container_of(to_delayed_work(work), struct gpio_extcon_data,
                             work);

        state = gpiod_get_value_cansleep(data->gpiod);
        extcon_set_state_sync(data->edev, data->extcon_id, state);
}

static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
{
        struct gpio_extcon_data *data = dev_id;

        queue_delayed_work(system_power_efficient_wq, &data->work,
                              data->debounce_jiffies);
        return IRQ_HANDLED;
}

static int gpio_extcon_probe(struct platform_device *pdev)
{
        struct gpio_extcon_data *data;
        struct device *dev = &pdev->dev;
        unsigned long irq_flags;
        int irq;
        int ret;

        data = devm_kzalloc(dev, sizeof(struct gpio_extcon_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        /*
         * FIXME: extcon_id represents the unique identifier of external
         * connectors such as EXTCON_USB, EXTCON_DISP_HDMI and so on. extcon_id
         * is necessary to register the extcon device. But, it's not yet
         * developed to get the extcon id from device-tree or others.
         * On later, it have to be solved.
         */
        if (data->extcon_id > EXTCON_NONE)
                return -EINVAL;

        data->gpiod = devm_gpiod_get(dev, "extcon", GPIOD_IN);
        if (IS_ERR(data->gpiod))
                return PTR_ERR(data->gpiod);
        irq = gpiod_to_irq(data->gpiod);
        if (irq <= 0)
                return irq;

        /*
         * It is unlikely that this is an acknowledged interrupt that goes
         * away after handling, what we are looking for are falling edges
         * if the signal is active low, and rising edges if the signal is
         * active high.
         */
        if (gpiod_is_active_low(data->gpiod))
                irq_flags = IRQF_TRIGGER_FALLING;
        else
                irq_flags = IRQF_TRIGGER_RISING;

        /* Allocate the memory of extcon devie and register extcon device */
        data->edev = devm_extcon_dev_allocate(dev, &data->extcon_id);
        if (IS_ERR(data->edev)) {
                dev_err(dev, "failed to allocate extcon device\n");
                return -ENOMEM;
        }

        ret = devm_extcon_dev_register(dev, data->edev);
        if (ret < 0)
                return ret;

        ret = devm_delayed_work_autocancel(dev, &data->work, gpio_extcon_work);
        if (ret)
                return ret;

        /*
         * Request the interrupt of gpio to detect whether external connector
         * is attached or detached.
         */
        ret = devm_request_any_context_irq(dev, irq,
                                        gpio_irq_handler, irq_flags,
                                        pdev->name, data);
        if (ret < 0)
                return ret;

        platform_set_drvdata(pdev, data);
        /* Perform initial detection */
        gpio_extcon_work(&data->work.work);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int gpio_extcon_resume(struct device *dev)
{
        struct gpio_extcon_data *data;

        data = dev_get_drvdata(dev);
        if (data->check_on_resume)
                queue_delayed_work(system_power_efficient_wq,
                        &data->work, data->debounce_jiffies);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);

static struct platform_driver gpio_extcon_driver = {
        .probe          = gpio_extcon_probe,
        .driver         = {
                .name   = "extcon-gpio",
                .pm     = &gpio_extcon_pm_ops,
        },
};

module_platform_driver(gpio_extcon_driver);

MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
MODULE_DESCRIPTION("GPIO extcon driver");
MODULE_LICENSE("GPL");