// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for SMSC USB4604 USB HSIC 4-port 2.0 hub controller driver
 * Based on usb3503 driver
 *
 * Copyright (c) 2012-2013 Dongjin Kim (tobetter@gmail.com)
 * Copyright (c) 2016 Linaro Ltd.
 */

#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/gpio/consumer.h>

enum usb4604_mode {
        USB4604_MODE_UNKNOWN,
        USB4604_MODE_HUB,
        USB4604_MODE_STANDBY,
};

struct usb4604 {
        enum usb4604_mode       mode;
        struct device           *dev;
        struct gpio_desc        *gpio_reset;
};

static void usb4604_reset(struct usb4604 *hub, int state)
{
        gpiod_set_value_cansleep(hub->gpio_reset, state);

        /* Wait for i2c logic to come up */
        if (state)
                msleep(250);
}

static int usb4604_connect(struct usb4604 *hub)
{
        struct device *dev = hub->dev;
        struct i2c_client *client = to_i2c_client(dev);
        int err;
        u8 connect_cmd[] = { 0xaa, 0x55, 0x00 };

        usb4604_reset(hub, 1);

        err = i2c_master_send(client, connect_cmd, ARRAY_SIZE(connect_cmd));
        if (err < 0) {
                usb4604_reset(hub, 0);
                return err;
        }

        hub->mode = USB4604_MODE_HUB;
        dev_dbg(dev, "switched to HUB mode\n");

        return 0;
}

static int usb4604_switch_mode(struct usb4604 *hub, enum usb4604_mode mode)
{
        struct device *dev = hub->dev;
        int err = 0;

        switch (mode) {
        case USB4604_MODE_HUB:
                err = usb4604_connect(hub);
                break;

        case USB4604_MODE_STANDBY:
                usb4604_reset(hub, 0);
                dev_dbg(dev, "switched to STANDBY mode\n");
                break;

        default:
                dev_err(dev, "unknown mode is requested\n");
                err = -EINVAL;
                break;
        }

        return err;
}

static int usb4604_probe(struct usb4604 *hub)
{
        struct device *dev = hub->dev;
        struct device_node *np = dev->of_node;
        struct gpio_desc *gpio;
        u32 mode = USB4604_MODE_HUB;

        gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
        if (IS_ERR(gpio))
                return PTR_ERR(gpio);
        hub->gpio_reset = gpio;

        if (of_property_read_u32(np, "initial-mode", &hub->mode))
                hub->mode = mode;

        return usb4604_switch_mode(hub, hub->mode);
}

static int usb4604_i2c_probe(struct i2c_client *i2c)
{
        struct usb4604 *hub;

        hub = devm_kzalloc(&i2c->dev, sizeof(*hub), GFP_KERNEL);
        if (!hub)
                return -ENOMEM;

        i2c_set_clientdata(i2c, hub);
        hub->dev = &i2c->dev;

        return usb4604_probe(hub);
}

static int __maybe_unused usb4604_i2c_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct usb4604 *hub = i2c_get_clientdata(client);

        usb4604_switch_mode(hub, USB4604_MODE_STANDBY);

        return 0;
}

static int __maybe_unused usb4604_i2c_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct usb4604 *hub = i2c_get_clientdata(client);

        usb4604_switch_mode(hub, hub->mode);

        return 0;
}

static SIMPLE_DEV_PM_OPS(usb4604_i2c_pm_ops, usb4604_i2c_suspend,
                usb4604_i2c_resume);

static const struct i2c_device_id usb4604_id[] = {
        { "usb4604" },
        { }
};
MODULE_DEVICE_TABLE(i2c, usb4604_id);

#ifdef CONFIG_OF
static const struct of_device_id usb4604_of_match[] = {
        { .compatible = "smsc,usb4604" },
        {}
};
MODULE_DEVICE_TABLE(of, usb4604_of_match);
#endif

static struct i2c_driver usb4604_i2c_driver = {
        .driver = {
                .name = "usb4604",
                .pm = pm_ptr(&usb4604_i2c_pm_ops),
                .of_match_table = of_match_ptr(usb4604_of_match),
        },
        .probe          = usb4604_i2c_probe,
        .id_table       = usb4604_id,
};
module_i2c_driver(usb4604_i2c_driver);

MODULE_DESCRIPTION("USB4604 USB HUB driver");
MODULE_LICENSE("GPL v2");