// 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");