/*
 * Allwinner EMAC MDIO interface driver
 *
 * Copyright 2012-2013 Stefan Roese <sr@denx.de>
 * Copyright 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * Based on the Linux driver provided by Allwinner:
 * Copyright (C) 1997  Sten Wang
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_address.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

#define EMAC_MAC_MCMD_REG	(0x00)
#define EMAC_MAC_MADR_REG	(0x04)
#define EMAC_MAC_MWTD_REG	(0x08)
#define EMAC_MAC_MRDD_REG	(0x0c)
#define EMAC_MAC_MIND_REG	(0x10)
#define EMAC_MAC_SSRR_REG	(0x14)

#define MDIO_TIMEOUT		(msecs_to_jiffies(100))

struct sun4i_mdio_data {
	void __iomem		*membase;
	struct regulator	*regulator;
};

static int sun4i_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
{
	struct sun4i_mdio_data *data = bus->priv;
	unsigned long start_jiffies;
	int value;

	/* issue the phy address and reg */
	writel((mii_id << 8) | regnum, data->membase + EMAC_MAC_MADR_REG);
	/* pull up the phy io line */
	writel(0x1, data->membase + EMAC_MAC_MCMD_REG);

	/* Wait read complete */
	start_jiffies = jiffies;
	while (readl(data->membase + EMAC_MAC_MIND_REG) & 0x1) {
		if (time_after(start_jiffies,
			       start_jiffies + MDIO_TIMEOUT))
			return -ETIMEDOUT;
		msleep(1);
	}

	/* push down the phy io line */
	writel(0x0, data->membase + EMAC_MAC_MCMD_REG);
	/* and read data */
	value = readl(data->membase + EMAC_MAC_MRDD_REG);

	return value;
}

static int sun4i_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
			    u16 value)
{
	struct sun4i_mdio_data *data = bus->priv;
	unsigned long start_jiffies;

	/* issue the phy address and reg */
	writel((mii_id << 8) | regnum, data->membase + EMAC_MAC_MADR_REG);
	/* pull up the phy io line */
	writel(0x1, data->membase + EMAC_MAC_MCMD_REG);

	/* Wait read complete */
	start_jiffies = jiffies;
	while (readl(data->membase + EMAC_MAC_MIND_REG) & 0x1) {
		if (time_after(start_jiffies,
			       start_jiffies + MDIO_TIMEOUT))
			return -ETIMEDOUT;
		msleep(1);
	}

	/* push down the phy io line */
	writel(0x0, data->membase + EMAC_MAC_MCMD_REG);
	/* and write data */
	writel(value, data->membase + EMAC_MAC_MWTD_REG);

	return 0;
}

static int sun4i_mdio_reset(struct mii_bus *bus)
{
	return 0;
}

static int sun4i_mdio_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct mii_bus *bus;
	struct sun4i_mdio_data *data;
	int ret, i;

	bus = mdiobus_alloc_size(sizeof(*data));
	if (!bus)
		return -ENOMEM;

	bus->name = "sun4i_mii_bus";
	bus->read = &sun4i_mdio_read;
	bus->write = &sun4i_mdio_write;
	bus->reset = &sun4i_mdio_reset;
	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii", dev_name(&pdev->dev));
	bus->parent = &pdev->dev;

	bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
	if (!bus->irq) {
		ret = -ENOMEM;
		goto err_out_free_mdiobus;
	}

	for (i = 0; i < PHY_MAX_ADDR; i++)
		bus->irq[i] = PHY_POLL;

	data = bus->priv;
	data->membase = of_iomap(np, 0);
	if (!data->membase) {
		ret = -ENOMEM;
		goto err_out_free_mdio_irq;
	}

	data->regulator = devm_regulator_get(&pdev->dev, "phy");
	if (IS_ERR(data->regulator)) {
		if (PTR_ERR(data->regulator) == -EPROBE_DEFER)
			return -EPROBE_DEFER;

		dev_info(&pdev->dev, "no regulator found\n");
	} else {
		ret = regulator_enable(data->regulator);
		if (ret)
			goto err_out_free_mdio_irq;
	}

	ret = of_mdiobus_register(bus, np);
	if (ret < 0)
		goto err_out_disable_regulator;

	platform_set_drvdata(pdev, bus);

	return 0;

err_out_disable_regulator:
	regulator_disable(data->regulator);
err_out_free_mdio_irq:
	kfree(bus->irq);
err_out_free_mdiobus:
	mdiobus_free(bus);
	return ret;
}

static int sun4i_mdio_remove(struct platform_device *pdev)
{
	struct mii_bus *bus = platform_get_drvdata(pdev);

	mdiobus_unregister(bus);
	kfree(bus->irq);
	mdiobus_free(bus);

	return 0;
}

static const struct of_device_id sun4i_mdio_dt_ids[] = {
	{ .compatible = "allwinner,sun4i-mdio" },
	{ }
};
MODULE_DEVICE_TABLE(of, sun4i_mdio_dt_ids);

static struct platform_driver sun4i_mdio_driver = {
	.probe = sun4i_mdio_probe,
	.remove = sun4i_mdio_remove,
	.driver = {
		.name = "sun4i-mdio",
		.of_match_table = sun4i_mdio_dt_ids,
	},
};

module_platform_driver(sun4i_mdio_driver);

MODULE_DESCRIPTION("Allwinner EMAC MDIO interface driver");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_LICENSE("GPL");