// SPDX-License-Identifier: GPL-2.0+
/*
 * Broadcom BCM6368 mdiomux bus controller driver
 *
 * Copyright (C) 2021 Álvaro Fernández Rojas <noltari@gmail.com>
 */

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mdio-mux.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/sched.h>

#define MDIOC_REG               0x0
#define MDIOC_EXT_MASK          BIT(16)
#define MDIOC_REG_SHIFT         20
#define MDIOC_PHYID_SHIFT       25
#define MDIOC_RD_MASK           BIT(30)
#define MDIOC_WR_MASK           BIT(31)

#define MDIOD_REG               0x4

struct bcm6368_mdiomux_desc {
        void *mux_handle;
        void __iomem *base;
        struct device *dev;
        struct mii_bus *mii_bus;
        int ext_phy;
};

static int bcm6368_mdiomux_read(struct mii_bus *bus, int phy_id, int loc)
{
        struct bcm6368_mdiomux_desc *md = bus->priv;
        uint32_t reg;
        int ret;

        __raw_writel(0, md->base + MDIOC_REG);

        reg = MDIOC_RD_MASK |
              (phy_id << MDIOC_PHYID_SHIFT) |
              (loc << MDIOC_REG_SHIFT);
        if (md->ext_phy)
                reg |= MDIOC_EXT_MASK;

        __raw_writel(reg, md->base + MDIOC_REG);
        udelay(50);
        ret = __raw_readw(md->base + MDIOD_REG);

        return ret;
}

static int bcm6368_mdiomux_write(struct mii_bus *bus, int phy_id, int loc,
                                 uint16_t val)
{
        struct bcm6368_mdiomux_desc *md = bus->priv;
        uint32_t reg;

        __raw_writel(0, md->base + MDIOC_REG);

        reg = MDIOC_WR_MASK |
              (phy_id << MDIOC_PHYID_SHIFT) |
              (loc << MDIOC_REG_SHIFT);
        if (md->ext_phy)
                reg |= MDIOC_EXT_MASK;
        reg |= val;

        __raw_writel(reg, md->base + MDIOC_REG);
        udelay(50);

        return 0;
}

static int bcm6368_mdiomux_switch_fn(int current_child, int desired_child,
                                     void *data)
{
        struct bcm6368_mdiomux_desc *md = data;

        md->ext_phy = desired_child;

        return 0;
}

static int bcm6368_mdiomux_probe(struct platform_device *pdev)
{
        struct bcm6368_mdiomux_desc *md;
        struct mii_bus *bus;
        struct resource *res;
        int rc;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -EINVAL;

        /*
         * Just ioremap, as this MDIO block is usually integrated into an
         * Ethernet MAC controller register range
         */
        md->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
        if (!md->base) {
                dev_err(&pdev->dev, "failed to ioremap register\n");
                return -ENOMEM;
        }

        md->mii_bus = devm_mdiobus_alloc(&pdev->dev);
        if (!md->mii_bus) {
                dev_err(&pdev->dev, "mdiomux bus alloc failed\n");
                return -ENOMEM;
        }

        bus = md->mii_bus;
        bus->priv = md;
        bus->name = "BCM6368 MDIO mux bus";
        snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
        bus->parent = &pdev->dev;
        bus->read = bcm6368_mdiomux_read;
        bus->write = bcm6368_mdiomux_write;
        bus->phy_mask = 0x3f;
        bus->dev.of_node = pdev->dev.of_node;

        rc = mdiobus_register(bus);
        if (rc) {
                dev_err(&pdev->dev, "mdiomux registration failed\n");
                return rc;
        }

        platform_set_drvdata(pdev, md);

        rc = mdio_mux_init(md->dev, md->dev->of_node,
                           bcm6368_mdiomux_switch_fn, &md->mux_handle, md,
                           md->mii_bus);
        if (rc) {
                dev_info(md->dev, "mdiomux initialization failed\n");
                goto out_register;
        }

        dev_info(&pdev->dev, "Broadcom BCM6368 MDIO mux bus\n");

        return 0;

out_register:
        mdiobus_unregister(bus);
        return rc;
}

static void bcm6368_mdiomux_remove(struct platform_device *pdev)
{
        struct bcm6368_mdiomux_desc *md = platform_get_drvdata(pdev);

        mdio_mux_uninit(md->mux_handle);
        mdiobus_unregister(md->mii_bus);
}

static const struct of_device_id bcm6368_mdiomux_ids[] = {
        { .compatible = "brcm,bcm6368-mdio-mux", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, bcm6368_mdiomux_ids);

static struct platform_driver bcm6368_mdiomux_driver = {
        .driver = {
                .name = "bcm6368-mdio-mux",
                .of_match_table = bcm6368_mdiomux_ids,
        },
        .probe  = bcm6368_mdiomux_probe,
        .remove = bcm6368_mdiomux_remove,
};
module_platform_driver(bcm6368_mdiomux_driver);

MODULE_AUTHOR("Álvaro Fernández Rojas <noltari@gmail.com>");
MODULE_DESCRIPTION("BCM6368 mdiomux bus controller driver");
MODULE_LICENSE("GPL v2");