// SPDX-License-Identifier: GPL-2.0
/*
 * GPIO based MDIO bitbang driver.
 * Supports OpenFirmware.
 *
 * Copyright (c) 2008 CSE Semaphore Belgium.
 *  by Laurent Pinchart <laurentp@cse-semaphore.com>
 *
 * Copyright (C) 2008, Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
 *
 * Based on earlier work by
 *
 * Copyright (c) 2003 Intracom S.A.
 *  by Pantelis Antoniou <panto@intracom.gr>
 *
 * 2005 (c) MontaVista Software, Inc.
 * Vitaly Bordug <vbordug@ru.mvista.com>
 */

#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/mdio-bitbang.h>
#include <linux/mdio-gpio.h>
#include <linux/module.h>
#include <linux/of_mdio.h>
#include <linux/platform_data/mdio-gpio.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

struct mdio_gpio_info {
        struct mdiobb_ctrl ctrl;
        struct gpio_desc *mdc, *mdio, *mdo;
};

static int mdio_gpio_get_data(struct device *dev,
                              struct mdio_gpio_info *bitbang)
{
        bitbang->mdc = devm_gpiod_get_index(dev, NULL, MDIO_GPIO_MDC,
                                            GPIOD_OUT_LOW);
        if (IS_ERR(bitbang->mdc))
                return PTR_ERR(bitbang->mdc);

        bitbang->mdio = devm_gpiod_get_index(dev, NULL, MDIO_GPIO_MDIO,
                                             GPIOD_IN);
        if (IS_ERR(bitbang->mdio))
                return PTR_ERR(bitbang->mdio);

        bitbang->mdo = devm_gpiod_get_index_optional(dev, NULL, MDIO_GPIO_MDO,
                                                     GPIOD_OUT_LOW);
        return PTR_ERR_OR_ZERO(bitbang->mdo);
}

static void mdio_dir(struct mdiobb_ctrl *ctrl, int dir)
{
        struct mdio_gpio_info *bitbang =
                container_of(ctrl, struct mdio_gpio_info, ctrl);

        if (bitbang->mdo) {
                /* Separate output pin. Always set its value to high
                 * when changing direction. If direction is input,
                 * assume the pin serves as pull-up. If direction is
                 * output, the default value is high.
                 */
                gpiod_set_value_cansleep(bitbang->mdo, 1);
                return;
        }

        if (dir)
                gpiod_direction_output(bitbang->mdio, 1);
        else
                gpiod_direction_input(bitbang->mdio);
}

static int mdio_get(struct mdiobb_ctrl *ctrl)
{
        struct mdio_gpio_info *bitbang =
                container_of(ctrl, struct mdio_gpio_info, ctrl);

        return gpiod_get_value_cansleep(bitbang->mdio);
}

static void mdio_set(struct mdiobb_ctrl *ctrl, int what)
{
        struct mdio_gpio_info *bitbang =
                container_of(ctrl, struct mdio_gpio_info, ctrl);

        if (bitbang->mdo)
                gpiod_set_value_cansleep(bitbang->mdo, what);
        else
                gpiod_set_value_cansleep(bitbang->mdio, what);
}

static void mdc_set(struct mdiobb_ctrl *ctrl, int what)
{
        struct mdio_gpio_info *bitbang =
                container_of(ctrl, struct mdio_gpio_info, ctrl);

        gpiod_set_value_cansleep(bitbang->mdc, what);
}

static const struct mdiobb_ops mdio_gpio_ops = {
        .owner = THIS_MODULE,
        .set_mdc = mdc_set,
        .set_mdio_dir = mdio_dir,
        .set_mdio_data = mdio_set,
        .get_mdio_data = mdio_get,
};

static struct mii_bus *mdio_gpio_bus_init(struct device *dev,
                                          struct mdio_gpio_info *bitbang,
                                          int bus_id)
{
        struct mdio_gpio_platform_data *pdata = dev_get_platdata(dev);
        struct mii_bus *new_bus;

        bitbang->ctrl.ops = &mdio_gpio_ops;

        new_bus = alloc_mdio_bitbang(&bitbang->ctrl);
        if (!new_bus)
                return NULL;

        new_bus->name = "GPIO Bitbanged MDIO";
        new_bus->parent = dev;

        if (bus_id != -1)
                snprintf(new_bus->id, sizeof(new_bus->id), "gpio-%x", bus_id);
        else
                strscpy(new_bus->id, "gpio", sizeof(new_bus->id));

        if (pdata) {
                new_bus->phy_mask = pdata->phy_mask;
                new_bus->phy_ignore_ta_mask = pdata->phy_ignore_ta_mask;
        }

        if (device_is_compatible(dev, "microchip,mdio-smi0")) {
                bitbang->ctrl.op_c22_read = 0;
                bitbang->ctrl.op_c22_write = 0;
                bitbang->ctrl.override_op_c22 = 1;
        }

        dev_set_drvdata(dev, new_bus);

        return new_bus;
}

static void mdio_gpio_bus_deinit(struct device *dev)
{
        struct mii_bus *bus = dev_get_drvdata(dev);

        free_mdio_bitbang(bus);
}

static void mdio_gpio_bus_destroy(struct device *dev)
{
        struct mii_bus *bus = dev_get_drvdata(dev);

        mdiobus_unregister(bus);
        mdio_gpio_bus_deinit(dev);
}

static int mdio_gpio_probe(struct platform_device *pdev)
{
        struct mdio_gpio_info *bitbang;
        struct mii_bus *new_bus;
        int ret, bus_id;

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

        ret = mdio_gpio_get_data(&pdev->dev, bitbang);
        if (ret)
                return ret;

        if (pdev->dev.of_node) {
                bus_id = of_alias_get_id(pdev->dev.of_node, "mdio-gpio");
                if (bus_id < 0) {
                        dev_warn(&pdev->dev, "failed to get alias id\n");
                        bus_id = 0;
                }
        } else {
                bus_id = pdev->id;
        }

        new_bus = mdio_gpio_bus_init(&pdev->dev, bitbang, bus_id);
        if (!new_bus)
                return -ENODEV;

        ret = of_mdiobus_register(new_bus, pdev->dev.of_node);
        if (ret)
                mdio_gpio_bus_deinit(&pdev->dev);

        return ret;
}

static void mdio_gpio_remove(struct platform_device *pdev)
{
        mdio_gpio_bus_destroy(&pdev->dev);
}

static const struct of_device_id mdio_gpio_of_match[] = {
        { .compatible = "virtual,mdio-gpio", },
        { .compatible = "microchip,mdio-smi0" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mdio_gpio_of_match);

static struct platform_driver mdio_gpio_driver = {
        .probe = mdio_gpio_probe,
        .remove = mdio_gpio_remove,
        .driver         = {
                .name   = "mdio-gpio",
                .of_match_table = mdio_gpio_of_match,
        },
};

module_platform_driver(mdio_gpio_driver);

MODULE_ALIAS("platform:mdio-gpio");
MODULE_AUTHOR("Laurent Pinchart, Paulius Zaleckas");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Generic driver for MDIO bus emulation using GPIO");