/*
 * Intel INT3496 ACPI device extcon driver
 *
 * Copyright (c) 2016 Hans de Goede <hdegoede@redhat.com>
 *
 * Based on android x86 kernel code which is:
 *
 * Copyright (c) 2014, Intel Corporation.
 * Author: David Cohen <david.a.cohen@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#define INT3496_GPIO_USB_ID     0
#define INT3496_GPIO_VBUS_EN    1
#define INT3496_GPIO_USB_MUX    2
#define DEBOUNCE_TIME           msecs_to_jiffies(50)

struct int3496_data {
        struct device *dev;
        struct extcon_dev *edev;
        struct delayed_work work;
        struct gpio_desc *gpio_usb_id;
        struct gpio_desc *gpio_vbus_en;
        struct gpio_desc *gpio_usb_mux;
        int usb_id_irq;
};

static const unsigned int int3496_cable[] = {
        EXTCON_USB_HOST,
        EXTCON_NONE,
};

static const struct acpi_gpio_params id_gpios = { INT3496_GPIO_USB_ID, 0, false };
static const struct acpi_gpio_params vbus_gpios = { INT3496_GPIO_VBUS_EN, 0, false };
static const struct acpi_gpio_params mux_gpios = { INT3496_GPIO_USB_MUX, 0, false };

static const struct acpi_gpio_mapping acpi_int3496_default_gpios[] = {
        { "id-gpios", &id_gpios, 1 },
        { "vbus-gpios", &vbus_gpios, 1 },
        { "mux-gpios", &mux_gpios, 1 },
        { },
};

static void int3496_do_usb_id(struct work_struct *work)
{
        struct int3496_data *data =
                container_of(work, struct int3496_data, work.work);
        int id = gpiod_get_value_cansleep(data->gpio_usb_id);

        /* id == 1: PERIPHERAL, id == 0: HOST */
        dev_dbg(data->dev, "Connected %s cable\n", id ? "PERIPHERAL" : "HOST");

        /*
         * Peripheral: set USB mux to peripheral and disable VBUS
         * Host: set USB mux to host and enable VBUS
         */
        if (!IS_ERR(data->gpio_usb_mux))
                gpiod_direction_output(data->gpio_usb_mux, id);

        if (!IS_ERR(data->gpio_vbus_en))
                gpiod_direction_output(data->gpio_vbus_en, !id);

        extcon_set_state_sync(data->edev, EXTCON_USB_HOST, !id);
}

static irqreturn_t int3496_thread_isr(int irq, void *priv)
{
        struct int3496_data *data = priv;

        /* Let the pin settle before processing it */
        mod_delayed_work(system_wq, &data->work, DEBOUNCE_TIME);

        return IRQ_HANDLED;
}

static int int3496_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct int3496_data *data;
        int ret;

        ret = devm_acpi_dev_add_driver_gpios(dev, acpi_int3496_default_gpios);
        if (ret) {
                dev_err(dev, "can't add GPIO ACPI mapping\n");
                return ret;
        }

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

        data->dev = dev;
        INIT_DELAYED_WORK(&data->work, int3496_do_usb_id);

        data->gpio_usb_id = devm_gpiod_get(dev, "id", GPIOD_IN);
        if (IS_ERR(data->gpio_usb_id)) {
                ret = PTR_ERR(data->gpio_usb_id);
                dev_err(dev, "can't request USB ID GPIO: %d\n", ret);
                return ret;
        } else if (gpiod_get_direction(data->gpio_usb_id) != GPIOF_DIR_IN) {
                dev_warn(dev, FW_BUG "USB ID GPIO not in input mode, fixing\n");
                gpiod_direction_input(data->gpio_usb_id);
        }

        data->usb_id_irq = gpiod_to_irq(data->gpio_usb_id);
        if (data->usb_id_irq < 0) {
                dev_err(dev, "can't get USB ID IRQ: %d\n", data->usb_id_irq);
                return data->usb_id_irq;
        }

        data->gpio_vbus_en = devm_gpiod_get(dev, "vbus", GPIOD_ASIS);
        if (IS_ERR(data->gpio_vbus_en))
                dev_info(dev, "can't request VBUS EN GPIO\n");

        data->gpio_usb_mux = devm_gpiod_get(dev, "mux", GPIOD_ASIS);
        if (IS_ERR(data->gpio_usb_mux))
                dev_info(dev, "can't request USB MUX GPIO\n");

        /* register extcon device */
        data->edev = devm_extcon_dev_allocate(dev, int3496_cable);
        if (IS_ERR(data->edev))
                return -ENOMEM;

        ret = devm_extcon_dev_register(dev, data->edev);
        if (ret < 0) {
                dev_err(dev, "can't register extcon device: %d\n", ret);
                return ret;
        }

        ret = devm_request_threaded_irq(dev, data->usb_id_irq,
                                        NULL, int3496_thread_isr,
                                        IRQF_SHARED | IRQF_ONESHOT |
                                        IRQF_TRIGGER_RISING |
                                        IRQF_TRIGGER_FALLING,
                                        dev_name(dev), data);
        if (ret < 0) {
                dev_err(dev, "can't request IRQ for USB ID GPIO: %d\n", ret);
                return ret;
        }

        /* queue initial processing of id-pin */
        queue_delayed_work(system_wq, &data->work, 0);

        platform_set_drvdata(pdev, data);

        return 0;
}

static int int3496_remove(struct platform_device *pdev)
{
        struct int3496_data *data = platform_get_drvdata(pdev);

        devm_free_irq(&pdev->dev, data->usb_id_irq, data);
        cancel_delayed_work_sync(&data->work);

        return 0;
}

static struct acpi_device_id int3496_acpi_match[] = {
        { "INT3496" },
        { }
};
MODULE_DEVICE_TABLE(acpi, int3496_acpi_match);

static struct platform_driver int3496_driver = {
        .driver = {
                .name = "intel-int3496",
                .acpi_match_table = int3496_acpi_match,
        },
        .probe = int3496_probe,
        .remove = int3496_remove,
};

module_platform_driver(int3496_driver);

MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_DESCRIPTION("Intel INT3496 ACPI device extcon driver");
MODULE_LICENSE("GPL");