/*
 * Cortina Systems Gemini SATA bridge add-on to Faraday FTIDE010
 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/bitops.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/delay.h>
#include <linux/reset.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/io.h>
#include "sata_gemini.h"

#define DRV_NAME "gemini_sata_bridge"

/**
 * struct sata_gemini - a state container for a Gemini SATA bridge
 * @dev: the containing device
 * @base: remapped I/O memory base
 * @muxmode: the current muxing mode
 * @ide_pins: if the device is using the plain IDE interface pins
 * @sata_bridge: if the device enables the SATA bridge
 * @sata0_reset: SATA0 reset handler
 * @sata1_reset: SATA1 reset handler
 * @sata0_pclk: SATA0 PCLK handler
 * @sata1_pclk: SATA1 PCLK handler
 */
struct sata_gemini {
	struct device *dev;
	void __iomem *base;
	enum gemini_muxmode muxmode;
	bool ide_pins;
	bool sata_bridge;
	struct reset_control *sata0_reset;
	struct reset_control *sata1_reset;
	struct clk *sata0_pclk;
	struct clk *sata1_pclk;
};

/* Global IDE PAD Skew Control Register */
#define GEMINI_GLOBAL_IDE_SKEW_CTRL		0x18
#define GEMINI_IDE1_HOST_STROBE_DELAY_SHIFT	28
#define GEMINI_IDE1_DEVICE_STROBE_DELAY_SHIFT	24
#define GEMINI_IDE1_OUTPUT_IO_SKEW_SHIFT	20
#define GEMINI_IDE1_INPUT_IO_SKEW_SHIFT		16
#define GEMINI_IDE0_HOST_STROBE_DELAY_SHIFT	12
#define GEMINI_IDE0_DEVICE_STROBE_DELAY_SHIFT	8
#define GEMINI_IDE0_OUTPUT_IO_SKEW_SHIFT	4
#define GEMINI_IDE0_INPUT_IO_SKEW_SHIFT		0

/* Miscellaneous Control Register */
#define GEMINI_GLOBAL_MISC_CTRL		0x30
/*
 * Values of IDE IOMUX bits in the misc control register
 *
 * Bits 26:24 are "IDE IO Select", which decides what SATA
 * adapters are connected to which of the two IDE/ATA
 * controllers in the Gemini. We can connect the two IDE blocks
 * to one SATA adapter each, both acting as master, or one IDE
 * blocks to two SATA adapters so the IDE block can act in a
 * master/slave configuration.
 *
 * We also bring out different blocks on the actual IDE
 * pins (not SATA pins) if (and only if) these are muxed in.
 *
 * 111-100 - Reserved
 * Mode 0: 000 - ata0 master <-> sata0
 *               ata1 master <-> sata1
 *               ata0 slave interface brought out on IDE pads
 * Mode 1: 001 - ata0 master <-> sata0
 *               ata1 master <-> sata1
 *               ata1 slave interface brought out on IDE pads
 * Mode 2: 010 - ata1 master <-> sata1
 *               ata1 slave  <-> sata0
 *               ata0 master and slave interfaces brought out
 *                    on IDE pads
 * Mode 3: 011 - ata0 master <-> sata0
 *               ata1 slave  <-> sata1
 *               ata1 master and slave interfaces brought out
 *                    on IDE pads
 */
#define GEMINI_IDE_IOMUX_MASK			(7 << 24)
#define GEMINI_IDE_IOMUX_MODE0			(0 << 24)
#define GEMINI_IDE_IOMUX_MODE1			(1 << 24)
#define GEMINI_IDE_IOMUX_MODE2			(2 << 24)
#define GEMINI_IDE_IOMUX_MODE3			(3 << 24)
#define GEMINI_IDE_IOMUX_SHIFT			(24)
#define GEMINI_IDE_PADS_ENABLE			BIT(4)
#define GEMINI_PFLASH_PADS_DISABLE		BIT(1)

/*
 * Registers directly controlling the PATA<->SATA adapters
 */
#define GEMINI_SATA_ID				0x00
#define GEMINI_SATA_PHY_ID			0x04
#define GEMINI_SATA0_STATUS			0x08
#define GEMINI_SATA1_STATUS			0x0c
#define GEMINI_SATA0_CTRL			0x18
#define GEMINI_SATA1_CTRL			0x1c

#define GEMINI_SATA_STATUS_BIST_DONE		BIT(5)
#define GEMINI_SATA_STATUS_BIST_OK		BIT(4)
#define GEMINI_SATA_STATUS_PHY_READY		BIT(0)

#define GEMINI_SATA_CTRL_PHY_BIST_EN		BIT(14)
#define GEMINI_SATA_CTRL_PHY_FORCE_IDLE		BIT(13)
#define GEMINI_SATA_CTRL_PHY_FORCE_READY	BIT(12)
#define GEMINI_SATA_CTRL_PHY_AFE_LOOP_EN	BIT(10)
#define GEMINI_SATA_CTRL_PHY_DIG_LOOP_EN	BIT(9)
#define GEMINI_SATA_CTRL_HOTPLUG_DETECT_EN	BIT(4)
#define GEMINI_SATA_CTRL_ATAPI_EN		BIT(3)
#define GEMINI_SATA_CTRL_BUS_WITH_20		BIT(2)
#define GEMINI_SATA_CTRL_SLAVE_EN		BIT(1)
#define GEMINI_SATA_CTRL_EN			BIT(0)

/*
 * There is only ever one instance of this bridge on a system,
 * so create a singleton so that the FTIDE010 instances can grab
 * a reference to it.
 */
static struct sata_gemini *sg_singleton;

struct sata_gemini *gemini_sata_bridge_get(void)
{
	if (sg_singleton)
		return sg_singleton;
	return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL(gemini_sata_bridge_get);

bool gemini_sata_bridge_enabled(struct sata_gemini *sg, bool is_ata1)
{
	if (!sg->sata_bridge)
		return false;
	/*
	 * In muxmode 2 and 3 one of the ATA controllers is
	 * actually not connected to any SATA bridge.
	 */
	if ((sg->muxmode == GEMINI_MUXMODE_2) &&
	    !is_ata1)
		return false;
	if ((sg->muxmode == GEMINI_MUXMODE_3) &&
	    is_ata1)
		return false;

	return true;
}
EXPORT_SYMBOL(gemini_sata_bridge_enabled);

enum gemini_muxmode gemini_sata_get_muxmode(struct sata_gemini *sg)
{
	return sg->muxmode;
}
EXPORT_SYMBOL(gemini_sata_get_muxmode);

static int gemini_sata_setup_bridge(struct sata_gemini *sg,
				    unsigned int bridge)
{
	unsigned long timeout = jiffies + (HZ * 1);
	bool bridge_online;
	u32 val;

	if (bridge == 0) {
		val = GEMINI_SATA_CTRL_HOTPLUG_DETECT_EN | GEMINI_SATA_CTRL_EN;
		/* SATA0 slave mode is only used in muxmode 2 */
		if (sg->muxmode == GEMINI_MUXMODE_2)
			val |= GEMINI_SATA_CTRL_SLAVE_EN;
		writel(val, sg->base + GEMINI_SATA0_CTRL);
	} else {
		val = GEMINI_SATA_CTRL_HOTPLUG_DETECT_EN | GEMINI_SATA_CTRL_EN;
		/* SATA1 slave mode is only used in muxmode 3 */
		if (sg->muxmode == GEMINI_MUXMODE_3)
			val |= GEMINI_SATA_CTRL_SLAVE_EN;
		writel(val, sg->base + GEMINI_SATA1_CTRL);
	}

	/* Vendor code waits 10 ms here */
	msleep(10);

	/* Wait for PHY to become ready */
	do {
		msleep(100);

		if (bridge == 0)
			val = readl(sg->base + GEMINI_SATA0_STATUS);
		else
			val = readl(sg->base + GEMINI_SATA1_STATUS);
		if (val & GEMINI_SATA_STATUS_PHY_READY)
			break;
	} while (time_before(jiffies, timeout));

	bridge_online = !!(val & GEMINI_SATA_STATUS_PHY_READY);

	dev_info(sg->dev, "SATA%d PHY %s\n", bridge,
		 bridge_online ? "ready" : "not ready");

	return bridge_online ? 0: -ENODEV;
}

int gemini_sata_start_bridge(struct sata_gemini *sg, unsigned int bridge)
{
	struct clk *pclk;
	int ret;

	if (bridge == 0)
		pclk = sg->sata0_pclk;
	else
		pclk = sg->sata1_pclk;
	clk_enable(pclk);
	msleep(10);

	/* Do not keep clocking a bridge that is not online */
	ret = gemini_sata_setup_bridge(sg, bridge);
	if (ret)
		clk_disable(pclk);

	return ret;
}
EXPORT_SYMBOL(gemini_sata_start_bridge);

void gemini_sata_stop_bridge(struct sata_gemini *sg, unsigned int bridge)
{
	if (bridge == 0)
		clk_disable(sg->sata0_pclk);
	else if (bridge == 1)
		clk_disable(sg->sata1_pclk);
}
EXPORT_SYMBOL(gemini_sata_stop_bridge);

int gemini_sata_reset_bridge(struct sata_gemini *sg,
			     unsigned int bridge)
{
	if (bridge == 0)
		reset_control_reset(sg->sata0_reset);
	else
		reset_control_reset(sg->sata1_reset);
	msleep(10);
	return gemini_sata_setup_bridge(sg, bridge);
}
EXPORT_SYMBOL(gemini_sata_reset_bridge);

static int gemini_sata_bridge_init(struct sata_gemini *sg)
{
	struct device *dev = sg->dev;
	u32 sata_id, sata_phy_id;
	int ret;

	sg->sata0_pclk = devm_clk_get(dev, "SATA0_PCLK");
	if (IS_ERR(sg->sata0_pclk)) {
		dev_err(dev, "no SATA0 PCLK");
		return -ENODEV;
	}
	sg->sata1_pclk = devm_clk_get(dev, "SATA1_PCLK");
	if (IS_ERR(sg->sata1_pclk)) {
		dev_err(dev, "no SATA1 PCLK");
		return -ENODEV;
	}

	ret = clk_prepare_enable(sg->sata0_pclk);
	if (ret) {
		pr_err("failed to enable SATA0 PCLK\n");
		return ret;
	}
	ret = clk_prepare_enable(sg->sata1_pclk);
	if (ret) {
		pr_err("failed to enable SATA1 PCLK\n");
		clk_disable_unprepare(sg->sata0_pclk);
		return ret;
	}

	sg->sata0_reset = devm_reset_control_get(dev, "sata0");
	if (IS_ERR(sg->sata0_reset)) {
		dev_err(dev, "no SATA0 reset controller\n");
		clk_disable_unprepare(sg->sata1_pclk);
		clk_disable_unprepare(sg->sata0_pclk);
		return PTR_ERR(sg->sata0_reset);
	}
	sg->sata1_reset = devm_reset_control_get(dev, "sata1");
	if (IS_ERR(sg->sata1_reset)) {
		dev_err(dev, "no SATA1 reset controller\n");
		clk_disable_unprepare(sg->sata1_pclk);
		clk_disable_unprepare(sg->sata0_pclk);
		return PTR_ERR(sg->sata1_reset);
	}

	sata_id = readl(sg->base + GEMINI_SATA_ID);
	sata_phy_id = readl(sg->base + GEMINI_SATA_PHY_ID);
	sg->sata_bridge = true;
	clk_disable(sg->sata0_pclk);
	clk_disable(sg->sata1_pclk);

	dev_info(dev, "SATA ID %08x, PHY ID: %08x\n", sata_id, sata_phy_id);

	return 0;
}

static int gemini_sata_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct sata_gemini *sg;
	static struct regmap *map;
	struct resource *res;
	enum gemini_muxmode muxmode;
	u32 gmode;
	u32 gmask;
	u32 val;
	int ret;

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENODEV;

	sg->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(sg->base))
		return PTR_ERR(sg->base);

	map = syscon_regmap_lookup_by_phandle(np, "syscon");
	if (IS_ERR(map)) {
		dev_err(dev, "no global syscon\n");
		return PTR_ERR(map);
	}

	/* Set up the SATA bridge if need be */
	if (of_property_read_bool(np, "cortina,gemini-enable-sata-bridge")) {
		ret = gemini_sata_bridge_init(sg);
		if (ret)
			return ret;
	}

	if (of_property_read_bool(np, "cortina,gemini-enable-ide-pins"))
		sg->ide_pins = true;

	if (!sg->sata_bridge && !sg->ide_pins) {
		dev_err(dev, "neither SATA bridge or IDE output enabled\n");
		ret = -EINVAL;
		goto out_unprep_clk;
	}

	ret = of_property_read_u32(np, "cortina,gemini-ata-muxmode", &muxmode);
	if (ret) {
		dev_err(dev, "could not parse ATA muxmode\n");
		goto out_unprep_clk;
	}
	if (muxmode > GEMINI_MUXMODE_3) {
		dev_err(dev, "illegal muxmode %d\n", muxmode);
		ret = -EINVAL;
		goto out_unprep_clk;
	}
	sg->muxmode = muxmode;
	gmask = GEMINI_IDE_IOMUX_MASK;
	gmode = (muxmode << GEMINI_IDE_IOMUX_SHIFT);

	/*
	 * If we mux out the IDE, parallel flash must be disabled.
	 * SATA0 and SATA1 have dedicated pins and may coexist with
	 * parallel flash.
	 */
	if (sg->ide_pins)
		gmode |= GEMINI_IDE_PADS_ENABLE | GEMINI_PFLASH_PADS_DISABLE;
	else
		gmask |= GEMINI_IDE_PADS_ENABLE;

	ret = regmap_update_bits(map, GEMINI_GLOBAL_MISC_CTRL, gmask, gmode);
	if (ret) {
		dev_err(dev, "unable to set up IDE muxing\n");
		ret = -ENODEV;
		goto out_unprep_clk;
	}

	/* FIXME: add more elaborate IDE skew control handling */
	if (sg->ide_pins) {
		ret = regmap_read(map, GEMINI_GLOBAL_IDE_SKEW_CTRL, &val);
		if (ret) {
			dev_err(dev, "cannot read IDE skew control register\n");
			return ret;
		}
		dev_info(dev, "IDE skew control: %08x\n", val);
	}

	dev_info(dev, "set up the Gemini IDE/SATA nexus\n");
	platform_set_drvdata(pdev, sg);
	sg_singleton = sg;

	return 0;

out_unprep_clk:
	if (sg->sata_bridge) {
		clk_unprepare(sg->sata1_pclk);
		clk_unprepare(sg->sata0_pclk);
	}
	return ret;
}

static int gemini_sata_remove(struct platform_device *pdev)
{
	struct sata_gemini *sg = platform_get_drvdata(pdev);

	if (sg->sata_bridge) {
		clk_unprepare(sg->sata1_pclk);
		clk_unprepare(sg->sata0_pclk);
	}
	sg_singleton = NULL;

	return 0;
}

static const struct of_device_id gemini_sata_of_match[] = {
	{
		.compatible = "cortina,gemini-sata-bridge",
	},
	{},
};

static struct platform_driver gemini_sata_driver = {
	.driver = {
		.name = DRV_NAME,
		.of_match_table = of_match_ptr(gemini_sata_of_match),
	},
	.probe = gemini_sata_probe,
	.remove = gemini_sata_remove,
};
module_platform_driver(gemini_sata_driver);

MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);