// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019 Baylibre, SAS.
 * Author: Jerome Brunet <jbrunet@baylibre.com>
 */

#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/mdio-mux.h>
#include <linux/module.h>
#include <linux/phy.h>
#include <linux/platform_device.h>

#define ETH_PLL_STS		0x40
#define ETH_PLL_CTL0		0x44
#define  PLL_CTL0_LOCK_DIG	BIT(30)
#define  PLL_CTL0_RST		BIT(29)
#define  PLL_CTL0_EN		BIT(28)
#define  PLL_CTL0_SEL		BIT(23)
#define  PLL_CTL0_N		GENMASK(14, 10)
#define  PLL_CTL0_M		GENMASK(8, 0)
#define  PLL_LOCK_TIMEOUT	1000000
#define  PLL_MUX_NUM_PARENT	2
#define ETH_PLL_CTL1		0x48
#define ETH_PLL_CTL2		0x4c
#define ETH_PLL_CTL3		0x50
#define ETH_PLL_CTL4		0x54
#define ETH_PLL_CTL5		0x58
#define ETH_PLL_CTL6		0x5c
#define ETH_PLL_CTL7		0x60

#define ETH_PHY_CNTL0		0x80
#define   EPHY_G12A_ID		0x33010180
#define ETH_PHY_CNTL1		0x84
#define  PHY_CNTL1_ST_MODE	GENMASK(2, 0)
#define  PHY_CNTL1_ST_PHYADD	GENMASK(7, 3)
#define   EPHY_DFLT_ADD		8
#define  PHY_CNTL1_MII_MODE	GENMASK(15, 14)
#define   EPHY_MODE_RMII	0x1
#define  PHY_CNTL1_CLK_EN	BIT(16)
#define  PHY_CNTL1_CLKFREQ	BIT(17)
#define  PHY_CNTL1_PHY_ENB	BIT(18)
#define ETH_PHY_CNTL2		0x88
#define  PHY_CNTL2_USE_INTERNAL	BIT(5)
#define  PHY_CNTL2_SMI_SRC_MAC	BIT(6)
#define  PHY_CNTL2_RX_CLK_EPHY	BIT(9)

#define MESON_G12A_MDIO_EXTERNAL_ID 0
#define MESON_G12A_MDIO_INTERNAL_ID 1

struct g12a_mdio_mux {
	bool pll_is_enabled;
	void __iomem *regs;
	void *mux_handle;
	struct clk *pclk;
	struct clk *pll;
};

struct g12a_ephy_pll {
	void __iomem *base;
	struct clk_hw hw;
};

#define g12a_ephy_pll_to_dev(_hw)			\
	container_of(_hw, struct g12a_ephy_pll, hw)

static unsigned long g12a_ephy_pll_recalc_rate(struct clk_hw *hw,
					       unsigned long parent_rate)
{
	struct g12a_ephy_pll *pll = g12a_ephy_pll_to_dev(hw);
	u32 val, m, n;

	val = readl(pll->base + ETH_PLL_CTL0);
	m = FIELD_GET(PLL_CTL0_M, val);
	n = FIELD_GET(PLL_CTL0_N, val);

	return parent_rate * m / n;
}

static int g12a_ephy_pll_enable(struct clk_hw *hw)
{
	struct g12a_ephy_pll *pll = g12a_ephy_pll_to_dev(hw);
	u32 val = readl(pll->base + ETH_PLL_CTL0);

	/* Apply both enable an reset */
	val |= PLL_CTL0_RST | PLL_CTL0_EN;
	writel(val, pll->base + ETH_PLL_CTL0);

	/* Clear the reset to let PLL lock */
	val &= ~PLL_CTL0_RST;
	writel(val, pll->base + ETH_PLL_CTL0);

	/* Poll on the digital lock instead of the usual analog lock
	 * This is done because bit 31 is unreliable on some SoC. Bit
	 * 31 may indicate that the PLL is not lock even though the clock
	 * is actually running
	 */
	return readl_poll_timeout(pll->base + ETH_PLL_CTL0, val,
				  val & PLL_CTL0_LOCK_DIG, 0, PLL_LOCK_TIMEOUT);
}

static void g12a_ephy_pll_disable(struct clk_hw *hw)
{
	struct g12a_ephy_pll *pll = g12a_ephy_pll_to_dev(hw);
	u32 val;

	val = readl(pll->base + ETH_PLL_CTL0);
	val &= ~PLL_CTL0_EN;
	val |= PLL_CTL0_RST;
	writel(val, pll->base + ETH_PLL_CTL0);
}

static int g12a_ephy_pll_is_enabled(struct clk_hw *hw)
{
	struct g12a_ephy_pll *pll = g12a_ephy_pll_to_dev(hw);
	unsigned int val;

	val = readl(pll->base + ETH_PLL_CTL0);

	return (val & PLL_CTL0_LOCK_DIG) ? 1 : 0;
}

static int g12a_ephy_pll_init(struct clk_hw *hw)
{
	struct g12a_ephy_pll *pll = g12a_ephy_pll_to_dev(hw);

	/* Apply PLL HW settings */
	writel(0x29c0040a, pll->base + ETH_PLL_CTL0);
	writel(0x927e0000, pll->base + ETH_PLL_CTL1);
	writel(0xac5f49e5, pll->base + ETH_PLL_CTL2);
	writel(0x00000000, pll->base + ETH_PLL_CTL3);
	writel(0x00000000, pll->base + ETH_PLL_CTL4);
	writel(0x20200000, pll->base + ETH_PLL_CTL5);
	writel(0x0000c002, pll->base + ETH_PLL_CTL6);
	writel(0x00000023, pll->base + ETH_PLL_CTL7);

	return 0;
}

static const struct clk_ops g12a_ephy_pll_ops = {
	.recalc_rate	= g12a_ephy_pll_recalc_rate,
	.is_enabled	= g12a_ephy_pll_is_enabled,
	.enable		= g12a_ephy_pll_enable,
	.disable	= g12a_ephy_pll_disable,
	.init		= g12a_ephy_pll_init,
};

static int g12a_enable_internal_mdio(struct g12a_mdio_mux *priv)
{
	u32 value;
	int ret;

	/* Enable the phy clock */
	if (!priv->pll_is_enabled) {
		ret = clk_prepare_enable(priv->pll);
		if (ret)
			return ret;
	}

	priv->pll_is_enabled = true;

	/* Initialize ephy control */
	writel(EPHY_G12A_ID, priv->regs + ETH_PHY_CNTL0);

	/* Make sure we get a 0 -> 1 transition on the enable bit */
	value = FIELD_PREP(PHY_CNTL1_ST_MODE, 3) |
		FIELD_PREP(PHY_CNTL1_ST_PHYADD, EPHY_DFLT_ADD) |
		FIELD_PREP(PHY_CNTL1_MII_MODE, EPHY_MODE_RMII) |
		PHY_CNTL1_CLK_EN |
		PHY_CNTL1_CLKFREQ;
	writel(value, priv->regs + ETH_PHY_CNTL1);
	writel(PHY_CNTL2_USE_INTERNAL |
	       PHY_CNTL2_SMI_SRC_MAC |
	       PHY_CNTL2_RX_CLK_EPHY,
	       priv->regs + ETH_PHY_CNTL2);

	value |= PHY_CNTL1_PHY_ENB;
	writel(value, priv->regs + ETH_PHY_CNTL1);

	/* The phy needs a bit of time to power up */
	mdelay(10);

	return 0;
}

static int g12a_enable_external_mdio(struct g12a_mdio_mux *priv)
{
	/* Reset the mdio bus mux */
	writel_relaxed(0x0, priv->regs + ETH_PHY_CNTL2);

	/* Disable the phy clock if enabled */
	if (priv->pll_is_enabled) {
		clk_disable_unprepare(priv->pll);
		priv->pll_is_enabled = false;
	}

	return 0;
}

static int g12a_mdio_switch_fn(int current_child, int desired_child,
			       void *data)
{
	struct g12a_mdio_mux *priv = dev_get_drvdata(data);

	if (current_child == desired_child)
		return 0;

	switch (desired_child) {
	case MESON_G12A_MDIO_EXTERNAL_ID:
		return g12a_enable_external_mdio(priv);
	case MESON_G12A_MDIO_INTERNAL_ID:
		return g12a_enable_internal_mdio(priv);
	default:
		return -EINVAL;
	}
}

static const struct of_device_id g12a_mdio_mux_match[] = {
	{ .compatible = "amlogic,g12a-mdio-mux", },
	{},
};
MODULE_DEVICE_TABLE(of, g12a_mdio_mux_match);

static int g12a_ephy_glue_clk_register(struct device *dev)
{
	struct g12a_mdio_mux *priv = dev_get_drvdata(dev);
	const char *parent_names[PLL_MUX_NUM_PARENT];
	struct clk_init_data init;
	struct g12a_ephy_pll *pll;
	struct clk_mux *mux;
	struct clk *clk;
	char *name;
	int i;

	/* get the mux parents */
	for (i = 0; i < PLL_MUX_NUM_PARENT; i++) {
		char in_name[8];

		snprintf(in_name, sizeof(in_name), "clkin%d", i);
		clk = devm_clk_get(dev, in_name);
		if (IS_ERR(clk))
			return dev_err_probe(dev, PTR_ERR(clk),
					     "Missing clock %s\n", in_name);

		parent_names[i] = __clk_get_name(clk);
	}

	/* create the input mux */
	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
	if (!mux)
		return -ENOMEM;

	name = kasprintf(GFP_KERNEL, "%s#mux", dev_name(dev));
	if (!name)
		return -ENOMEM;

	init.name = name;
	init.ops = &clk_mux_ro_ops;
	init.flags = 0;
	init.parent_names = parent_names;
	init.num_parents = PLL_MUX_NUM_PARENT;

	mux->reg = priv->regs + ETH_PLL_CTL0;
	mux->shift = __ffs(PLL_CTL0_SEL);
	mux->mask = PLL_CTL0_SEL >> mux->shift;
	mux->hw.init = &init;

	clk = devm_clk_register(dev, &mux->hw);
	kfree(name);
	if (IS_ERR(clk)) {
		dev_err(dev, "failed to register input mux\n");
		return PTR_ERR(clk);
	}

	/* create the pll */
	pll = devm_kzalloc(dev, sizeof(*pll), GFP_KERNEL);
	if (!pll)
		return -ENOMEM;

	name = kasprintf(GFP_KERNEL, "%s#pll", dev_name(dev));
	if (!name)
		return -ENOMEM;

	init.name = name;
	init.ops = &g12a_ephy_pll_ops;
	init.flags = 0;
	parent_names[0] = __clk_get_name(clk);
	init.parent_names = parent_names;
	init.num_parents = 1;

	pll->base = priv->regs;
	pll->hw.init = &init;

	clk = devm_clk_register(dev, &pll->hw);
	kfree(name);
	if (IS_ERR(clk)) {
		dev_err(dev, "failed to register input mux\n");
		return PTR_ERR(clk);
	}

	priv->pll = clk;

	return 0;
}

static int g12a_mdio_mux_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct g12a_mdio_mux *priv;
	int ret;

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

	platform_set_drvdata(pdev, priv);

	priv->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(priv->regs))
		return PTR_ERR(priv->regs);

	priv->pclk = devm_clk_get(dev, "pclk");
	if (IS_ERR(priv->pclk))
		return dev_err_probe(dev, PTR_ERR(priv->pclk),
				     "failed to get peripheral clock\n");

	/* Make sure the device registers are clocked */
	ret = clk_prepare_enable(priv->pclk);
	if (ret) {
		dev_err(dev, "failed to enable peripheral clock");
		return ret;
	}

	/* Register PLL in CCF */
	ret = g12a_ephy_glue_clk_register(dev);
	if (ret)
		goto err;

	ret = mdio_mux_init(dev, dev->of_node, g12a_mdio_switch_fn,
			    &priv->mux_handle, dev, NULL);
	if (ret) {
		dev_err_probe(dev, ret, "mdio multiplexer init failed\n");
		goto err;
	}

	return 0;

err:
	clk_disable_unprepare(priv->pclk);
	return ret;
}

static int g12a_mdio_mux_remove(struct platform_device *pdev)
{
	struct g12a_mdio_mux *priv = platform_get_drvdata(pdev);

	mdio_mux_uninit(priv->mux_handle);

	if (priv->pll_is_enabled)
		clk_disable_unprepare(priv->pll);

	clk_disable_unprepare(priv->pclk);

	return 0;
}

static struct platform_driver g12a_mdio_mux_driver = {
	.probe		= g12a_mdio_mux_probe,
	.remove		= g12a_mdio_mux_remove,
	.driver		= {
		.name	= "g12a-mdio_mux",
		.of_match_table = g12a_mdio_mux_match,
	},
};
module_platform_driver(g12a_mdio_mux_driver);

MODULE_DESCRIPTION("Amlogic G12a MDIO multiplexer driver");
MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
MODULE_LICENSE("GPL v2");