// SPDX-License-Identifier: GPL-2.0+
/*
 * Broadcom UniMAC MDIO bus controller driver
 *
 * Copyright (C) 2014-2017 Broadcom
 */

#include <linux/kernel.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/clk.h>

#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_mdio.h>

#include <linux/platform_data/mdio-bcm-unimac.h>

#define MDIO_CMD                0x00
#define  MDIO_START_BUSY        (1 << 29)
#define  MDIO_READ_FAIL         (1 << 28)
#define  MDIO_RD                (2 << 26)
#define  MDIO_WR                (1 << 26)
#define  MDIO_PMD_SHIFT         21
#define  MDIO_PMD_MASK          0x1F
#define  MDIO_REG_SHIFT         16
#define  MDIO_REG_MASK          0x1F

#define MDIO_CFG                0x04
#define  MDIO_C22               (1 << 0)
#define  MDIO_C45               0
#define  MDIO_CLK_DIV_SHIFT     4
#define  MDIO_CLK_DIV_MASK      0x3F
#define  MDIO_SUPP_PREAMBLE     (1 << 12)

struct unimac_mdio_priv {
        struct mii_bus          *mii_bus;
        void __iomem            *base;
        int (*wait_func)        (void *wait_func_data);
        void                    *wait_func_data;
        struct clk              *clk;
        u32                     clk_freq;
};

static inline u32 unimac_mdio_readl(struct unimac_mdio_priv *priv, u32 offset)
{
        /* MIPS chips strapped for BE will automagically configure the
         * peripheral registers for CPU-native byte order.
         */
        if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
                return __raw_readl(priv->base + offset);
        else
                return readl_relaxed(priv->base + offset);
}

static inline void unimac_mdio_writel(struct unimac_mdio_priv *priv, u32 val,
                                      u32 offset)
{
        if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
                __raw_writel(val, priv->base + offset);
        else
                writel_relaxed(val, priv->base + offset);
}

static inline void unimac_mdio_start(struct unimac_mdio_priv *priv)
{
        u32 reg;

        reg = unimac_mdio_readl(priv, MDIO_CMD);
        reg |= MDIO_START_BUSY;
        unimac_mdio_writel(priv, reg, MDIO_CMD);
}

static inline unsigned int unimac_mdio_busy(struct unimac_mdio_priv *priv)
{
        return unimac_mdio_readl(priv, MDIO_CMD) & MDIO_START_BUSY;
}

static int unimac_mdio_poll(void *wait_func_data)
{
        struct unimac_mdio_priv *priv = wait_func_data;
        unsigned int timeout = 1000;

        do {
                if (!unimac_mdio_busy(priv))
                        return 0;

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

        return -ETIMEDOUT;
}

static int unimac_mdio_read(struct mii_bus *bus, int phy_id, int reg)
{
        struct unimac_mdio_priv *priv = bus->priv;
        int ret;
        u32 cmd;

        /* Prepare the read operation */
        cmd = MDIO_RD | (phy_id << MDIO_PMD_SHIFT) | (reg << MDIO_REG_SHIFT);
        unimac_mdio_writel(priv, cmd, MDIO_CMD);

        /* Start MDIO transaction */
        unimac_mdio_start(priv);

        ret = priv->wait_func(priv->wait_func_data);
        if (ret)
                return ret;

        cmd = unimac_mdio_readl(priv, MDIO_CMD);

        /* Some broken devices are known not to release the line during
         * turn-around, e.g: Broadcom BCM53125 external switches, so check for
         * that condition here and ignore the MDIO controller read failure
         * indication.
         */
        if (!(bus->phy_ignore_ta_mask & 1 << phy_id) && (cmd & MDIO_READ_FAIL))
                return -EIO;

        return cmd & 0xffff;
}

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

        /* Prepare the write operation */
        cmd = MDIO_WR | (phy_id << MDIO_PMD_SHIFT) |
                (reg << MDIO_REG_SHIFT) | (0xffff & val);
        unimac_mdio_writel(priv, cmd, MDIO_CMD);

        unimac_mdio_start(priv);

        return priv->wait_func(priv->wait_func_data);
}

/* Workaround for integrated BCM7xxx Gigabit PHYs which have a problem with
 * their internal MDIO management controller making them fail to successfully
 * be read from or written to for the first transaction.  We insert a dummy
 * BMSR read here to make sure that phy_get_device() and get_phy_id() can
 * correctly read the PHY MII_PHYSID1/2 registers and successfully register a
 * PHY device for this peripheral.
 *
 * Once the PHY driver is registered, we can workaround subsequent reads from
 * there (e.g: during system-wide power management).
 *
 * bus->reset is invoked before mdiobus_scan during mdiobus_register and is
 * therefore the right location to stick that workaround. Since we do not want
 * to read from non-existing PHYs, we either use bus->phy_mask or do a manual
 * Device Tree scan to limit the search area.
 */
static int unimac_mdio_reset(struct mii_bus *bus)
{
        struct device_node *np = bus->dev.of_node;
        struct device_node *child;
        u32 read_mask = 0;
        int addr;

        if (!np) {
                read_mask = ~bus->phy_mask;
        } else {
                for_each_available_child_of_node(np, child) {
                        addr = of_mdio_parse_addr(&bus->dev, child);
                        if (addr < 0)
                                continue;

                        read_mask |= 1 << addr;
                }
        }

        for (addr = 0; addr < PHY_MAX_ADDR; addr++) {
                if (read_mask & 1 << addr) {
                        dev_dbg(&bus->dev, "Workaround for PHY @ %d\n", addr);
                        mdiobus_read(bus, addr, MII_BMSR);
                }
        }

        return 0;
}

static void unimac_mdio_clk_set(struct unimac_mdio_priv *priv)
{
        unsigned long rate;
        u32 reg, div;

        /* Keep the hardware default values */
        if (!priv->clk_freq)
                return;

        if (!priv->clk)
                rate = 250000000;
        else
                rate = clk_get_rate(priv->clk);

        div = (rate / (2 * priv->clk_freq)) - 1;
        if (div & ~MDIO_CLK_DIV_MASK) {
                pr_warn("Incorrect MDIO clock frequency, ignoring\n");
                return;
        }

        /* The MDIO clock is the reference clock (typicaly 250Mhz) divided by
         * 2 x (MDIO_CLK_DIV + 1)
         */
        reg = unimac_mdio_readl(priv, MDIO_CFG);
        reg &= ~(MDIO_CLK_DIV_MASK << MDIO_CLK_DIV_SHIFT);
        reg |= div << MDIO_CLK_DIV_SHIFT;
        unimac_mdio_writel(priv, reg, MDIO_CFG);
}

static int unimac_mdio_probe(struct platform_device *pdev)
{
        struct unimac_mdio_pdata *pdata = pdev->dev.platform_data;
        struct unimac_mdio_priv *priv;
        struct device_node *np;
        struct mii_bus *bus;
        struct resource *r;
        int ret;

        np = pdev->dev.of_node;

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

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

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

        priv->clk = devm_clk_get(&pdev->dev, NULL);
        if (PTR_ERR(priv->clk) == -EPROBE_DEFER)
                return PTR_ERR(priv->clk);
        else
                priv->clk = NULL;

        ret = clk_prepare_enable(priv->clk);
        if (ret)
                return ret;

        if (of_property_read_u32(np, "clock-frequency", &priv->clk_freq))
                priv->clk_freq = 0;

        unimac_mdio_clk_set(priv);

        priv->mii_bus = mdiobus_alloc();
        if (!priv->mii_bus) {
                ret = -ENOMEM;
                goto out_clk_disable;
        }

        bus = priv->mii_bus;
        bus->priv = priv;
        if (pdata) {
                bus->name = pdata->bus_name;
                priv->wait_func = pdata->wait_func;
                priv->wait_func_data = pdata->wait_func_data;
                bus->phy_mask = ~pdata->phy_mask;
        } else {
                bus->name = "unimac MII bus";
                priv->wait_func_data = priv;
                priv->wait_func = unimac_mdio_poll;
        }
        bus->parent = &pdev->dev;
        bus->read = unimac_mdio_read;
        bus->write = unimac_mdio_write;
        bus->reset = unimac_mdio_reset;
        snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d", pdev->name, pdev->id);

        ret = of_mdiobus_register(bus, np);
        if (ret) {
                dev_err(&pdev->dev, "MDIO bus registration failed\n");
                goto out_mdio_free;
        }

        platform_set_drvdata(pdev, priv);

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

        return 0;

out_mdio_free:
        mdiobus_free(bus);
out_clk_disable:
        clk_disable_unprepare(priv->clk);
        return ret;
}

static int unimac_mdio_remove(struct platform_device *pdev)
{
        struct unimac_mdio_priv *priv = platform_get_drvdata(pdev);

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

        return 0;
}

static int __maybe_unused unimac_mdio_suspend(struct device *d)
{
        struct unimac_mdio_priv *priv = dev_get_drvdata(d);

        clk_disable_unprepare(priv->clk);

        return 0;
}

static int __maybe_unused unimac_mdio_resume(struct device *d)
{
        struct unimac_mdio_priv *priv = dev_get_drvdata(d);
        int ret;

        ret = clk_prepare_enable(priv->clk);
        if (ret)
                return ret;

        unimac_mdio_clk_set(priv);

        return 0;
}

static SIMPLE_DEV_PM_OPS(unimac_mdio_pm_ops,
                         unimac_mdio_suspend, unimac_mdio_resume);

static const struct of_device_id unimac_mdio_ids[] = {
        { .compatible = "brcm,genet-mdio-v5", },
        { .compatible = "brcm,genet-mdio-v4", },
        { .compatible = "brcm,genet-mdio-v3", },
        { .compatible = "brcm,genet-mdio-v2", },
        { .compatible = "brcm,genet-mdio-v1", },
        { .compatible = "brcm,unimac-mdio", },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, unimac_mdio_ids);

static struct platform_driver unimac_mdio_driver = {
        .driver = {
                .name = UNIMAC_MDIO_DRV_NAME,
                .of_match_table = unimac_mdio_ids,
                .pm = &unimac_mdio_pm_ops,
        },
        .probe  = unimac_mdio_probe,
        .remove = unimac_mdio_remove,
};
module_platform_driver(unimac_mdio_driver);

MODULE_AUTHOR("Broadcom Corporation");
MODULE_DESCRIPTION("Broadcom UniMAC MDIO bus controller");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" UNIMAC_MDIO_DRV_NAME);