// SPDX-License-Identifier: GPL-2.0-or-later
/* Driver for MMIO-Mapped MDIO devices. Some IPs expose internal PHYs or PCS
 * within the MMIO-mapped area
 *
 * Copyright (C) 2023 Maxime Chevallier <maxime.chevallier@bootlin.com>
 */
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/mdio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/mdio/mdio-regmap.h>

#define DRV_NAME "mdio-regmap"

struct mdio_regmap_priv {
        struct regmap *regmap;
        u8 valid_addr;
};

static int mdio_regmap_read_c22(struct mii_bus *bus, int addr, int regnum)
{
        struct mdio_regmap_priv *ctx = bus->priv;
        unsigned int val;
        int ret;

        if (ctx->valid_addr != addr)
                return -ENODEV;

        ret = regmap_read(ctx->regmap, regnum, &val);
        if (ret < 0)
                return ret;

        return val;
}

static int mdio_regmap_write_c22(struct mii_bus *bus, int addr, int regnum,
                                 u16 val)
{
        struct mdio_regmap_priv *ctx = bus->priv;

        if (ctx->valid_addr != addr)
                return -ENODEV;

        return regmap_write(ctx->regmap, regnum, val);
}

struct mii_bus *devm_mdio_regmap_register(struct device *dev,
                                          const struct mdio_regmap_config *config)
{
        struct mdio_regmap_priv *mr;
        struct mii_bus *mii;
        int rc;

        if (!config->parent)
                return ERR_PTR(-EINVAL);

        mii = devm_mdiobus_alloc_size(config->parent, sizeof(*mr));
        if (!mii)
                return ERR_PTR(-ENOMEM);

        mr = mii->priv;
        mr->regmap = config->regmap;
        mr->valid_addr = config->valid_addr;

        mii->name = DRV_NAME;
        strscpy(mii->id, config->name, MII_BUS_ID_SIZE);
        mii->parent = config->parent;
        mii->read = mdio_regmap_read_c22;
        mii->write = mdio_regmap_write_c22;

        if (config->autoscan)
                mii->phy_mask = ~BIT(config->valid_addr);
        else
                mii->phy_mask = ~0;

        rc = devm_mdiobus_register(dev, mii);
        if (rc) {
                dev_err(config->parent, "Cannot register MDIO bus![%s] (%d)\n", mii->id, rc);
                return ERR_PTR(rc);
        }

        return mii;
}
EXPORT_SYMBOL_GPL(devm_mdio_regmap_register);

MODULE_DESCRIPTION("MDIO API over regmap");
MODULE_AUTHOR("Maxime Chevallier <maxime.chevallier@bootlin.com>");
MODULE_LICENSE("GPL");