// SPDX-License-Identifier: GPL-2.0
/*
 * Allwinner EMAC MDIO interface driver
 *
 * Copyright 2012-2013 Stefan Roese <sr@denx.de>
 * Copyright 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * Based on the Linux driver provided by Allwinner:
 * Copyright (C) 1997  Sten Wang
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_address.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

#define EMAC_MAC_MCMD_REG       (0x00)
#define EMAC_MAC_MADR_REG       (0x04)
#define EMAC_MAC_MWTD_REG       (0x08)
#define EMAC_MAC_MRDD_REG       (0x0c)
#define EMAC_MAC_MIND_REG       (0x10)
#define EMAC_MAC_SSRR_REG       (0x14)

#define MDIO_TIMEOUT            (msecs_to_jiffies(100))

struct sun4i_mdio_data {
        void __iomem            *membase;
        struct regulator        *regulator;
};

static int sun4i_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
{
        struct sun4i_mdio_data *data = bus->priv;
        unsigned long timeout_jiffies;
        int value;

        /* issue the phy address and reg */
        writel((mii_id << 8) | regnum, data->membase + EMAC_MAC_MADR_REG);
        /* pull up the phy io line */
        writel(0x1, data->membase + EMAC_MAC_MCMD_REG);

        /* Wait read complete */
        timeout_jiffies = jiffies + MDIO_TIMEOUT;
        while (readl(data->membase + EMAC_MAC_MIND_REG) & 0x1) {
                if (time_is_before_jiffies(timeout_jiffies))
                        return -ETIMEDOUT;
                msleep(1);
        }

        /* push down the phy io line */
        writel(0x0, data->membase + EMAC_MAC_MCMD_REG);
        /* and read data */
        value = readl(data->membase + EMAC_MAC_MRDD_REG);

        return value;
}

static int sun4i_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
                            u16 value)
{
        struct sun4i_mdio_data *data = bus->priv;
        unsigned long timeout_jiffies;

        /* issue the phy address and reg */
        writel((mii_id << 8) | regnum, data->membase + EMAC_MAC_MADR_REG);
        /* pull up the phy io line */
        writel(0x1, data->membase + EMAC_MAC_MCMD_REG);

        /* Wait read complete */
        timeout_jiffies = jiffies + MDIO_TIMEOUT;
        while (readl(data->membase + EMAC_MAC_MIND_REG) & 0x1) {
                if (time_is_before_jiffies(timeout_jiffies))
                        return -ETIMEDOUT;
                msleep(1);
        }

        /* push down the phy io line */
        writel(0x0, data->membase + EMAC_MAC_MCMD_REG);
        /* and write data */
        writel(value, data->membase + EMAC_MAC_MWTD_REG);

        return 0;
}

static int sun4i_mdio_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct mii_bus *bus;
        struct sun4i_mdio_data *data;
        int ret;

        bus = mdiobus_alloc_size(sizeof(*data));
        if (!bus)
                return -ENOMEM;

        bus->name = "sun4i_mii_bus";
        bus->read = &sun4i_mdio_read;
        bus->write = &sun4i_mdio_write;
        snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii", dev_name(&pdev->dev));
        bus->parent = &pdev->dev;

        data = bus->priv;
        data->membase = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(data->membase)) {
                ret = PTR_ERR(data->membase);
                goto err_out_free_mdiobus;
        }

        data->regulator = devm_regulator_get(&pdev->dev, "phy");
        if (IS_ERR(data->regulator)) {
                if (PTR_ERR(data->regulator) == -EPROBE_DEFER) {
                        ret = -EPROBE_DEFER;
                        goto err_out_free_mdiobus;
                }

                dev_info(&pdev->dev, "no regulator found\n");
                data->regulator = NULL;
        } else {
                ret = regulator_enable(data->regulator);
                if (ret)
                        goto err_out_free_mdiobus;
        }

        ret = of_mdiobus_register(bus, np);
        if (ret < 0)
                goto err_out_disable_regulator;

        platform_set_drvdata(pdev, bus);

        return 0;

err_out_disable_regulator:
        if (data->regulator)
                regulator_disable(data->regulator);
err_out_free_mdiobus:
        mdiobus_free(bus);
        return ret;
}

static void sun4i_mdio_remove(struct platform_device *pdev)
{
        struct mii_bus *bus = platform_get_drvdata(pdev);
        struct sun4i_mdio_data *data = bus->priv;

        mdiobus_unregister(bus);
        if (data->regulator)
                regulator_disable(data->regulator);
        mdiobus_free(bus);
}

static const struct of_device_id sun4i_mdio_dt_ids[] = {
        { .compatible = "allwinner,sun4i-a10-mdio" },

        /* Deprecated */
        { .compatible = "allwinner,sun4i-mdio" },
        { }
};
MODULE_DEVICE_TABLE(of, sun4i_mdio_dt_ids);

static struct platform_driver sun4i_mdio_driver = {
        .probe = sun4i_mdio_probe,
        .remove = sun4i_mdio_remove,
        .driver = {
                .name = "sun4i-mdio",
                .of_match_table = sun4i_mdio_dt_ids,
        },
};

module_platform_driver(sun4i_mdio_driver);

MODULE_DESCRIPTION("Allwinner EMAC MDIO interface driver");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_LICENSE("GPL v2");