// SPDX-License-Identifier: GPL-2.0-only
/*
 * Nuvoton DWMAC specific glue layer
 *
 * Copyright (C) 2025 Nuvoton Technology Corp.
 *
 * Author: Joey Lu <a0987203069@gmail.com>
 */

#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/of_net.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/stmmac.h>

#include "stmmac_platform.h"

#define NVT_REG_SYS_GMAC0MISCR  0x108
#define NVT_REG_SYS_GMAC1MISCR  0x10C

#define NVT_MISCR_RMII          BIT(0)

/* Two thousand picoseconds are evenly mapped to a 4-bit field,
 * resulting in each step being 2000/15 picoseconds.
 */
#define NVT_PATH_DELAY_STEP     134
#define NVT_TX_DELAY_MASK       GENMASK(19, 16)
#define NVT_RX_DELAY_MASK       GENMASK(23, 20)

struct nvt_priv_data {
        struct device *dev;
        struct regmap *regmap;
        u32 macid;
};

static int nvt_gmac_get_delay(struct device *dev, const char *property)
{
        u32 arg;

        if (of_property_read_u32(dev->of_node, property, &arg))
                return 0;

        if (arg > 2000)
                return -EINVAL;

        if (arg == 2000)
                return 15;

        return arg / NVT_PATH_DELAY_STEP;
}

static int nvt_set_phy_intf_sel(void *bsp_priv, u8 phy_intf_sel)
{
        struct nvt_priv_data *priv = bsp_priv;
        u32 reg, val;
        int ret;

        if (phy_intf_sel == PHY_INTF_SEL_RGMII) {
                ret = nvt_gmac_get_delay(priv->dev, "rx-internal-delay-ps");
                if (ret < 0)
                        return ret;
                val = FIELD_PREP(NVT_RX_DELAY_MASK, ret);

                ret = nvt_gmac_get_delay(priv->dev, "tx-internal-delay-ps");
                if (ret < 0)
                        return ret;
                val |= FIELD_PREP(NVT_TX_DELAY_MASK, ret);
        } else if (phy_intf_sel == PHY_INTF_SEL_RMII) {
                val = NVT_MISCR_RMII;
        } else {
                return -EINVAL;
        }

        reg = (priv->macid == 0) ? NVT_REG_SYS_GMAC0MISCR : NVT_REG_SYS_GMAC1MISCR;
        regmap_update_bits(priv->regmap, reg,
                           NVT_RX_DELAY_MASK | NVT_TX_DELAY_MASK | NVT_MISCR_RMII, val);

        return 0;
}

static int nvt_gmac_probe(struct platform_device *pdev)
{
        struct plat_stmmacenet_data *plat_dat;
        struct stmmac_resources stmmac_res;
        struct device *dev = &pdev->dev;
        struct nvt_priv_data *priv;
        int ret;

        ret = stmmac_get_platform_resources(pdev, &stmmac_res);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to get platform resources\n");

        plat_dat = devm_stmmac_probe_config_dt(pdev, stmmac_res.mac);
        if (IS_ERR(plat_dat))
                return dev_err_probe(dev, PTR_ERR(plat_dat), "Failed to get platform data\n");

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return dev_err_probe(dev, -ENOMEM, "Failed to allocate private data\n");

        priv->dev = dev;

        priv->regmap = syscon_regmap_lookup_by_phandle_args(dev->of_node, "nuvoton,sys",
                                                            1, &priv->macid);
        if (IS_ERR(priv->regmap))
                return dev_err_probe(dev, PTR_ERR(priv->regmap), "Failed to get sys register\n");

        if (priv->macid > 1)
                return dev_err_probe(dev, -EINVAL, "Invalid sys arguments\n");

        plat_dat->bsp_priv = priv;
        plat_dat->set_phy_intf_sel = nvt_set_phy_intf_sel;

        return stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
}

static const struct of_device_id nvt_dwmac_match[] = {
        { .compatible = "nuvoton,ma35d1-dwmac"},
        { }
};
MODULE_DEVICE_TABLE(of, nvt_dwmac_match);

static struct platform_driver nvt_dwmac_driver = {
        .probe  = nvt_gmac_probe,
        .remove = stmmac_pltfr_remove,
        .driver = {
                .name           = "nuvoton-dwmac",
                .pm             = &stmmac_pltfr_pm_ops,
                .of_match_table = nvt_dwmac_match,
        },
};
module_platform_driver(nvt_dwmac_driver);

MODULE_AUTHOR("Joey Lu <a0987203069@gmail.com>");
MODULE_DESCRIPTION("Nuvoton DWMAC specific glue layer");
MODULE_LICENSE("GPL");