/*
 * Copyright (C) 2015 Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.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 IPROC_GPHY_MDCDIV    0x1a

#define MII_CTRL_OFFSET      0x000

#define MII_CTRL_DIV_SHIFT   0
#define MII_CTRL_PRE_SHIFT   7
#define MII_CTRL_BUSY_SHIFT  8

#define MII_DATA_OFFSET      0x004
#define MII_DATA_MASK        0xffff
#define MII_DATA_TA_SHIFT    16
#define MII_DATA_TA_VAL      2
#define MII_DATA_RA_SHIFT    18
#define MII_DATA_PA_SHIFT    23
#define MII_DATA_OP_SHIFT    28
#define MII_DATA_OP_WRITE    1
#define MII_DATA_OP_READ     2
#define MII_DATA_SB_SHIFT    30

struct iproc_mdio_priv {
        struct mii_bus *mii_bus;
        void __iomem *base;
};

static inline int iproc_mdio_wait_for_idle(void __iomem *base)
{
        u32 val;
        unsigned int timeout = 1000; /* loop for 1s */

        do {
                val = readl(base + MII_CTRL_OFFSET);
                if ((val & BIT(MII_CTRL_BUSY_SHIFT)) == 0)
                        return 0;

                usleep_range(1000, 2000);
        } while (timeout--);

        return -ETIMEDOUT;
}

static inline void iproc_mdio_config_clk(void __iomem *base)
{
        u32 val;

        val = (IPROC_GPHY_MDCDIV << MII_CTRL_DIV_SHIFT) |
                  BIT(MII_CTRL_PRE_SHIFT);
        writel(val, base + MII_CTRL_OFFSET);
}

static int iproc_mdio_read(struct mii_bus *bus, int phy_id, int reg)
{
        struct iproc_mdio_priv *priv = bus->priv;
        u32 cmd;
        int rc;

        rc = iproc_mdio_wait_for_idle(priv->base);
        if (rc)
                return rc;

        iproc_mdio_config_clk(priv->base);

        /* Prepare the read operation */
        cmd = (MII_DATA_TA_VAL << MII_DATA_TA_SHIFT) |
                (reg << MII_DATA_RA_SHIFT) |
                (phy_id << MII_DATA_PA_SHIFT) |
                BIT(MII_DATA_SB_SHIFT) |
                (MII_DATA_OP_READ << MII_DATA_OP_SHIFT);

        writel(cmd, priv->base + MII_DATA_OFFSET);

        rc = iproc_mdio_wait_for_idle(priv->base);
        if (rc)
                return rc;

        cmd = readl(priv->base + MII_DATA_OFFSET) & MII_DATA_MASK;

        return cmd;
}

static int iproc_mdio_write(struct mii_bus *bus, int phy_id,
                            int reg, u16 val)
{
        struct iproc_mdio_priv *priv = bus->priv;
        u32 cmd;
        int rc;

        rc = iproc_mdio_wait_for_idle(priv->base);
        if (rc)
                return rc;

        iproc_mdio_config_clk(priv->base);

        /* Prepare the write operation */
        cmd = (MII_DATA_TA_VAL << MII_DATA_TA_SHIFT) |
                (reg << MII_DATA_RA_SHIFT) |
                (phy_id << MII_DATA_PA_SHIFT) |
                BIT(MII_DATA_SB_SHIFT) |
                (MII_DATA_OP_WRITE << MII_DATA_OP_SHIFT) |
                ((u32)(val) & MII_DATA_MASK);

        writel(cmd, priv->base + MII_DATA_OFFSET);

        rc = iproc_mdio_wait_for_idle(priv->base);
        if (rc)
                return rc;

        return 0;
}

static int iproc_mdio_probe(struct platform_device *pdev)
{
        struct iproc_mdio_priv *priv;
        struct mii_bus *bus;
        struct resource *res;
        int rc;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        priv->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(priv->base)) {
                dev_err(&pdev->dev, "failed to ioremap register\n");
                return PTR_ERR(priv->base);
        }

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

        bus = priv->mii_bus;
        bus->priv = priv;
        bus->name = "iProc MDIO bus";
        snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);
        bus->parent = &pdev->dev;
        bus->read = iproc_mdio_read;
        bus->write = iproc_mdio_write;

        rc = of_mdiobus_register(bus, pdev->dev.of_node);
        if (rc) {
                dev_err(&pdev->dev, "MDIO bus registration failed\n");
                goto err_iproc_mdio;
        }

        platform_set_drvdata(pdev, priv);

        dev_info(&pdev->dev, "Broadcom iProc MDIO bus at 0x%p\n", priv->base);

        return 0;

err_iproc_mdio:
        mdiobus_free(bus);
        return rc;
}

static int iproc_mdio_remove(struct platform_device *pdev)
{
        struct iproc_mdio_priv *priv = platform_get_drvdata(pdev);

        mdiobus_unregister(priv->mii_bus);
        mdiobus_free(priv->mii_bus);

        return 0;
}

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

static struct platform_driver iproc_mdio_driver = {
        .driver = {
                .name = "iproc-mdio",
                .of_match_table = iproc_mdio_of_match,
        },
        .probe = iproc_mdio_probe,
        .remove = iproc_mdio_remove,
};

module_platform_driver(iproc_mdio_driver);

MODULE_AUTHOR("Broadcom Corporation");
MODULE_DESCRIPTION("Broadcom iProc MDIO bus controller");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:iproc-mdio");