/*
 * Maxim Integrated MAX3355 USB OTG chip extcon driver
 *
 * Copyright (C)  2014-2015 Cogent Embedded, Inc.
 * Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 */

#include <linux/extcon.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>

struct max3355_data {
	struct extcon_dev *edev;
	struct gpio_desc *id_gpiod;
	struct gpio_desc *shdn_gpiod;
};

static const unsigned int max3355_cable[] = {
	EXTCON_USB,
	EXTCON_USB_HOST,
	EXTCON_NONE,
};

static irqreturn_t max3355_id_irq(int irq, void *dev_id)
{
	struct max3355_data *data = dev_id;
	int id = gpiod_get_value_cansleep(data->id_gpiod);

	if (id) {
		/*
		 * ID = 1 means USB HOST cable detached.
		 * As we don't have event for USB peripheral cable attached,
		 * we simulate USB peripheral attach here.
		 */
		extcon_set_state_sync(data->edev, EXTCON_USB_HOST, false);
		extcon_set_state_sync(data->edev, EXTCON_USB, true);
	} else {
		/*
		 * ID = 0 means USB HOST cable attached.
		 * As we don't have event for USB peripheral cable detached,
		 * we simulate USB peripheral detach here.
		 */
		extcon_set_state_sync(data->edev, EXTCON_USB, false);
		extcon_set_state_sync(data->edev, EXTCON_USB_HOST, true);
	}

	return IRQ_HANDLED;
}

static int max3355_probe(struct platform_device *pdev)
{
	struct max3355_data *data;
	struct gpio_desc *gpiod;
	int irq, err;

	data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data),
			    GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	gpiod = devm_gpiod_get(&pdev->dev, "id", GPIOD_IN);
	if (IS_ERR(gpiod)) {
		dev_err(&pdev->dev, "failed to get ID_OUT GPIO\n");
		return PTR_ERR(gpiod);
	}
	data->id_gpiod = gpiod;

	gpiod = devm_gpiod_get(&pdev->dev, "maxim,shdn", GPIOD_OUT_HIGH);
	if (IS_ERR(gpiod)) {
		dev_err(&pdev->dev, "failed to get SHDN# GPIO\n");
		return PTR_ERR(gpiod);
	}
	data->shdn_gpiod = gpiod;

	data->edev = devm_extcon_dev_allocate(&pdev->dev, max3355_cable);
	if (IS_ERR(data->edev)) {
		dev_err(&pdev->dev, "failed to allocate extcon device\n");
		return PTR_ERR(data->edev);
	}

	err = devm_extcon_dev_register(&pdev->dev, data->edev);
	if (err < 0) {
		dev_err(&pdev->dev, "failed to register extcon device\n");
		return err;
	}

	irq = gpiod_to_irq(data->id_gpiod);
	if (irq < 0) {
		dev_err(&pdev->dev, "failed to translate ID_OUT GPIO to IRQ\n");
		return irq;
	}

	err = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq,
					IRQF_ONESHOT | IRQF_NO_SUSPEND |
					IRQF_TRIGGER_RISING |
					IRQF_TRIGGER_FALLING,
					pdev->name, data);
	if (err < 0) {
		dev_err(&pdev->dev, "failed to request ID_OUT IRQ\n");
		return err;
	}

	platform_set_drvdata(pdev, data);

	/* Perform initial detection */
	max3355_id_irq(irq, data);

	return 0;
}

static int max3355_remove(struct platform_device *pdev)
{
	struct max3355_data *data = platform_get_drvdata(pdev);

	gpiod_set_value_cansleep(data->shdn_gpiod, 0);

	return 0;
}

static const struct of_device_id max3355_match_table[] = {
	{ .compatible = "maxim,max3355", },
	{ }
};
MODULE_DEVICE_TABLE(of, max3355_match_table);

static struct platform_driver max3355_driver = {
	.probe		= max3355_probe,
	.remove		= max3355_remove,
	.driver		= {
		.name	= "extcon-max3355",
		.of_match_table = max3355_match_table,
	},
};

module_platform_driver(max3355_driver);

MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>");
MODULE_DESCRIPTION("Maxim MAX3355 extcon driver");
MODULE_LICENSE("GPL v2");