/*
 * Rockchip USB2.0 PHY with Innosilicon IP block driver
 *
 * Copyright (C) 2016 Fuzhou Rockchip Electronics Co., Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/gpio/consumer.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/phy/phy.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#define BIT_WRITEABLE_SHIFT	16
#define SCHEDULE_DELAY	(60 * HZ)

enum rockchip_usb2phy_port_id {
	USB2PHY_PORT_OTG,
	USB2PHY_PORT_HOST,
	USB2PHY_NUM_PORTS,
};

enum rockchip_usb2phy_host_state {
	PHY_STATE_HS_ONLINE	= 0,
	PHY_STATE_DISCONNECT	= 1,
	PHY_STATE_CONNECT	= 2,
	PHY_STATE_FS_LS_ONLINE	= 4,
};

struct usb2phy_reg {
	unsigned int	offset;
	unsigned int	bitend;
	unsigned int	bitstart;
	unsigned int	disable;
	unsigned int	enable;
};

/**
 * struct rockchip_usb2phy_port_cfg: usb-phy port configuration.
 * @phy_sus: phy suspend register.
 * @ls_det_en: linestate detection enable register.
 * @ls_det_st: linestate detection state register.
 * @ls_det_clr: linestate detection clear register.
 * @utmi_ls: utmi linestate state register.
 * @utmi_hstdet: utmi host disconnect register.
 */
struct rockchip_usb2phy_port_cfg {
	struct usb2phy_reg	phy_sus;
	struct usb2phy_reg	ls_det_en;
	struct usb2phy_reg	ls_det_st;
	struct usb2phy_reg	ls_det_clr;
	struct usb2phy_reg	utmi_ls;
	struct usb2phy_reg	utmi_hstdet;
};

/**
 * struct rockchip_usb2phy_cfg: usb-phy configuration.
 * @reg: the address offset of grf for usb-phy config.
 * @num_ports: specify how many ports that the phy has.
 * @clkout_ctl: keep on/turn off output clk of phy.
 */
struct rockchip_usb2phy_cfg {
	unsigned int	reg;
	unsigned int	num_ports;
	struct usb2phy_reg	clkout_ctl;
	const struct rockchip_usb2phy_port_cfg	port_cfgs[USB2PHY_NUM_PORTS];
};

/**
 * struct rockchip_usb2phy_port: usb-phy port data.
 * @port_id: flag for otg port or host port.
 * @suspended: phy suspended flag.
 * @ls_irq: IRQ number assigned for linestate detection.
 * @mutex: for register updating in sm_work.
 * @sm_work: OTG state machine work.
 * @phy_cfg: port register configuration, assigned by driver data.
 */
struct rockchip_usb2phy_port {
	struct phy	*phy;
	unsigned int	port_id;
	bool		suspended;
	int		ls_irq;
	struct mutex	mutex;
	struct		delayed_work sm_work;
	const struct	rockchip_usb2phy_port_cfg *port_cfg;
};

/**
 * struct rockchip_usb2phy: usb2.0 phy driver data.
 * @grf: General Register Files regmap.
 * @clk: clock struct of phy input clk.
 * @clk480m: clock struct of phy output clk.
 * @clk_hw: clock struct of phy output clk management.
 * @phy_cfg: phy register configuration, assigned by driver data.
 * @ports: phy port instance.
 */
struct rockchip_usb2phy {
	struct device	*dev;
	struct regmap	*grf;
	struct clk	*clk;
	struct clk	*clk480m;
	struct clk_hw	clk480m_hw;
	const struct rockchip_usb2phy_cfg	*phy_cfg;
	struct rockchip_usb2phy_port	ports[USB2PHY_NUM_PORTS];
};

static inline int property_enable(struct rockchip_usb2phy *rphy,
				  const struct usb2phy_reg *reg, bool en)
{
	unsigned int val, mask, tmp;

	tmp = en ? reg->enable : reg->disable;
	mask = GENMASK(reg->bitend, reg->bitstart);
	val = (tmp << reg->bitstart) | (mask << BIT_WRITEABLE_SHIFT);

	return regmap_write(rphy->grf, reg->offset, val);
}

static inline bool property_enabled(struct rockchip_usb2phy *rphy,
				    const struct usb2phy_reg *reg)
{
	int ret;
	unsigned int tmp, orig;
	unsigned int mask = GENMASK(reg->bitend, reg->bitstart);

	ret = regmap_read(rphy->grf, reg->offset, &orig);
	if (ret)
		return false;

	tmp = (orig & mask) >> reg->bitstart;
	return tmp == reg->enable;
}

static int rockchip_usb2phy_clk480m_enable(struct clk_hw *hw)
{
	struct rockchip_usb2phy *rphy =
		container_of(hw, struct rockchip_usb2phy, clk480m_hw);
	int ret;

	/* turn on 480m clk output if it is off */
	if (!property_enabled(rphy, &rphy->phy_cfg->clkout_ctl)) {
		ret = property_enable(rphy, &rphy->phy_cfg->clkout_ctl, true);
		if (ret)
			return ret;

		/* waitting for the clk become stable */
		mdelay(1);
	}

	return 0;
}

static void rockchip_usb2phy_clk480m_disable(struct clk_hw *hw)
{
	struct rockchip_usb2phy *rphy =
		container_of(hw, struct rockchip_usb2phy, clk480m_hw);

	/* turn off 480m clk output */
	property_enable(rphy, &rphy->phy_cfg->clkout_ctl, false);
}

static int rockchip_usb2phy_clk480m_enabled(struct clk_hw *hw)
{
	struct rockchip_usb2phy *rphy =
		container_of(hw, struct rockchip_usb2phy, clk480m_hw);

	return property_enabled(rphy, &rphy->phy_cfg->clkout_ctl);
}

static unsigned long
rockchip_usb2phy_clk480m_recalc_rate(struct clk_hw *hw,
				     unsigned long parent_rate)
{
	return 480000000;
}

static const struct clk_ops rockchip_usb2phy_clkout_ops = {
	.enable = rockchip_usb2phy_clk480m_enable,
	.disable = rockchip_usb2phy_clk480m_disable,
	.is_enabled = rockchip_usb2phy_clk480m_enabled,
	.recalc_rate = rockchip_usb2phy_clk480m_recalc_rate,
};

static void rockchip_usb2phy_clk480m_unregister(void *data)
{
	struct rockchip_usb2phy *rphy = data;

	of_clk_del_provider(rphy->dev->of_node);
	clk_unregister(rphy->clk480m);
}

static int
rockchip_usb2phy_clk480m_register(struct rockchip_usb2phy *rphy)
{
	struct device_node *node = rphy->dev->of_node;
	struct clk_init_data init;
	const char *clk_name;
	int ret;

	init.flags = 0;
	init.name = "clk_usbphy_480m";
	init.ops = &rockchip_usb2phy_clkout_ops;

	/* optional override of the clockname */
	of_property_read_string(node, "clock-output-names", &init.name);

	if (rphy->clk) {
		clk_name = __clk_get_name(rphy->clk);
		init.parent_names = &clk_name;
		init.num_parents = 1;
	} else {
		init.parent_names = NULL;
		init.num_parents = 0;
	}

	rphy->clk480m_hw.init = &init;

	/* register the clock */
	rphy->clk480m = clk_register(rphy->dev, &rphy->clk480m_hw);
	if (IS_ERR(rphy->clk480m)) {
		ret = PTR_ERR(rphy->clk480m);
		goto err_ret;
	}

	ret = of_clk_add_provider(node, of_clk_src_simple_get, rphy->clk480m);
	if (ret < 0)
		goto err_clk_provider;

	ret = devm_add_action(rphy->dev, rockchip_usb2phy_clk480m_unregister,
			      rphy);
	if (ret < 0)
		goto err_unreg_action;

	return 0;

err_unreg_action:
	of_clk_del_provider(node);
err_clk_provider:
	clk_unregister(rphy->clk480m);
err_ret:
	return ret;
}

static int rockchip_usb2phy_init(struct phy *phy)
{
	struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);
	struct rockchip_usb2phy *rphy = dev_get_drvdata(phy->dev.parent);
	int ret;

	if (rport->port_id == USB2PHY_PORT_HOST) {
		/* clear linestate and enable linestate detect irq */
		mutex_lock(&rport->mutex);

		ret = property_enable(rphy, &rport->port_cfg->ls_det_clr, true);
		if (ret) {
			mutex_unlock(&rport->mutex);
			return ret;
		}

		ret = property_enable(rphy, &rport->port_cfg->ls_det_en, true);
		if (ret) {
			mutex_unlock(&rport->mutex);
			return ret;
		}

		mutex_unlock(&rport->mutex);
		schedule_delayed_work(&rport->sm_work, SCHEDULE_DELAY);
	}

	return 0;
}

static int rockchip_usb2phy_power_on(struct phy *phy)
{
	struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);
	struct rockchip_usb2phy *rphy = dev_get_drvdata(phy->dev.parent);
	int ret;

	dev_dbg(&rport->phy->dev, "port power on\n");

	if (!rport->suspended)
		return 0;

	ret = clk_prepare_enable(rphy->clk480m);
	if (ret)
		return ret;

	ret = property_enable(rphy, &rport->port_cfg->phy_sus, false);
	if (ret)
		return ret;

	rport->suspended = false;
	return 0;
}

static int rockchip_usb2phy_power_off(struct phy *phy)
{
	struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);
	struct rockchip_usb2phy *rphy = dev_get_drvdata(phy->dev.parent);
	int ret;

	dev_dbg(&rport->phy->dev, "port power off\n");

	if (rport->suspended)
		return 0;

	ret = property_enable(rphy, &rport->port_cfg->phy_sus, true);
	if (ret)
		return ret;

	rport->suspended = true;
	clk_disable_unprepare(rphy->clk480m);

	return 0;
}

static int rockchip_usb2phy_exit(struct phy *phy)
{
	struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);

	if (rport->port_id == USB2PHY_PORT_HOST)
		cancel_delayed_work_sync(&rport->sm_work);

	return 0;
}

static const struct phy_ops rockchip_usb2phy_ops = {
	.init		= rockchip_usb2phy_init,
	.exit		= rockchip_usb2phy_exit,
	.power_on	= rockchip_usb2phy_power_on,
	.power_off	= rockchip_usb2phy_power_off,
	.owner		= THIS_MODULE,
};

/*
 * The function manage host-phy port state and suspend/resume phy port
 * to save power.
 *
 * we rely on utmi_linestate and utmi_hostdisconnect to identify whether
 * devices is disconnect or not. Besides, we do not need care it is FS/LS
 * disconnected or HS disconnected, actually, we just only need get the
 * device is disconnected at last through rearm the delayed work,
 * to suspend the phy port in _PHY_STATE_DISCONNECT_ case.
 *
 * NOTE: It may invoke *phy_powr_off or *phy_power_on which will invoke
 * some clk related APIs, so do not invoke it from interrupt context directly.
 */
static void rockchip_usb2phy_sm_work(struct work_struct *work)
{
	struct rockchip_usb2phy_port *rport =
		container_of(work, struct rockchip_usb2phy_port, sm_work.work);
	struct rockchip_usb2phy *rphy = dev_get_drvdata(rport->phy->dev.parent);
	unsigned int sh = rport->port_cfg->utmi_hstdet.bitend -
			  rport->port_cfg->utmi_hstdet.bitstart + 1;
	unsigned int ul, uhd, state;
	unsigned int ul_mask, uhd_mask;
	int ret;

	mutex_lock(&rport->mutex);

	ret = regmap_read(rphy->grf, rport->port_cfg->utmi_ls.offset, &ul);
	if (ret < 0)
		goto next_schedule;

	ret = regmap_read(rphy->grf, rport->port_cfg->utmi_hstdet.offset,
			  &uhd);
	if (ret < 0)
		goto next_schedule;

	uhd_mask = GENMASK(rport->port_cfg->utmi_hstdet.bitend,
			   rport->port_cfg->utmi_hstdet.bitstart);
	ul_mask = GENMASK(rport->port_cfg->utmi_ls.bitend,
			  rport->port_cfg->utmi_ls.bitstart);

	/* stitch on utmi_ls and utmi_hstdet as phy state */
	state = ((uhd & uhd_mask) >> rport->port_cfg->utmi_hstdet.bitstart) |
		(((ul & ul_mask) >> rport->port_cfg->utmi_ls.bitstart) << sh);

	switch (state) {
	case PHY_STATE_HS_ONLINE:
		dev_dbg(&rport->phy->dev, "HS online\n");
		break;
	case PHY_STATE_FS_LS_ONLINE:
		/*
		 * For FS/LS device, the online state share with connect state
		 * from utmi_ls and utmi_hstdet register, so we distinguish
		 * them via suspended flag.
		 *
		 * Plus, there are two cases, one is D- Line pull-up, and D+
		 * line pull-down, the state is 4; another is D+ line pull-up,
		 * and D- line pull-down, the state is 2.
		 */
		if (!rport->suspended) {
			/* D- line pull-up, D+ line pull-down */
			dev_dbg(&rport->phy->dev, "FS/LS online\n");
			break;
		}
		/* fall through */
	case PHY_STATE_CONNECT:
		if (rport->suspended) {
			dev_dbg(&rport->phy->dev, "Connected\n");
			rockchip_usb2phy_power_on(rport->phy);
			rport->suspended = false;
		} else {
			/* D+ line pull-up, D- line pull-down */
			dev_dbg(&rport->phy->dev, "FS/LS online\n");
		}
		break;
	case PHY_STATE_DISCONNECT:
		if (!rport->suspended) {
			dev_dbg(&rport->phy->dev, "Disconnected\n");
			rockchip_usb2phy_power_off(rport->phy);
			rport->suspended = true;
		}

		/*
		 * activate the linestate detection to get the next device
		 * plug-in irq.
		 */
		property_enable(rphy, &rport->port_cfg->ls_det_clr, true);
		property_enable(rphy, &rport->port_cfg->ls_det_en, true);

		/*
		 * we don't need to rearm the delayed work when the phy port
		 * is suspended.
		 */
		mutex_unlock(&rport->mutex);
		return;
	default:
		dev_dbg(&rport->phy->dev, "unknown phy state\n");
		break;
	}

next_schedule:
	mutex_unlock(&rport->mutex);
	schedule_delayed_work(&rport->sm_work, SCHEDULE_DELAY);
}

static irqreturn_t rockchip_usb2phy_linestate_irq(int irq, void *data)
{
	struct rockchip_usb2phy_port *rport = data;
	struct rockchip_usb2phy *rphy = dev_get_drvdata(rport->phy->dev.parent);

	if (!property_enabled(rphy, &rport->port_cfg->ls_det_st))
		return IRQ_NONE;

	mutex_lock(&rport->mutex);

	/* disable linestate detect irq and clear its status */
	property_enable(rphy, &rport->port_cfg->ls_det_en, false);
	property_enable(rphy, &rport->port_cfg->ls_det_clr, true);

	mutex_unlock(&rport->mutex);

	/*
	 * In this case for host phy port, a new device is plugged in,
	 * meanwhile, if the phy port is suspended, we need rearm the work to
	 * resume it and mange its states; otherwise, we do nothing about that.
	 */
	if (rport->suspended && rport->port_id == USB2PHY_PORT_HOST)
		rockchip_usb2phy_sm_work(&rport->sm_work.work);

	return IRQ_HANDLED;
}

static int rockchip_usb2phy_host_port_init(struct rockchip_usb2phy *rphy,
					   struct rockchip_usb2phy_port *rport,
					   struct device_node *child_np)
{
	int ret;

	rport->port_id = USB2PHY_PORT_HOST;
	rport->port_cfg = &rphy->phy_cfg->port_cfgs[USB2PHY_PORT_HOST];
	rport->suspended = true;

	mutex_init(&rport->mutex);
	INIT_DELAYED_WORK(&rport->sm_work, rockchip_usb2phy_sm_work);

	rport->ls_irq = of_irq_get_byname(child_np, "linestate");
	if (rport->ls_irq < 0) {
		dev_err(rphy->dev, "no linestate irq provided\n");
		return rport->ls_irq;
	}

	ret = devm_request_threaded_irq(rphy->dev, rport->ls_irq, NULL,
					rockchip_usb2phy_linestate_irq,
					IRQF_ONESHOT,
					"rockchip_usb2phy", rport);
	if (ret) {
		dev_err(rphy->dev, "failed to request irq handle\n");
		return ret;
	}

	return 0;
}

static int rockchip_usb2phy_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct device_node *child_np;
	struct phy_provider *provider;
	struct rockchip_usb2phy *rphy;
	const struct rockchip_usb2phy_cfg *phy_cfgs;
	const struct of_device_id *match;
	unsigned int reg;
	int index, ret;

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

	match = of_match_device(dev->driver->of_match_table, dev);
	if (!match || !match->data) {
		dev_err(dev, "phy configs are not assigned!\n");
		return -EINVAL;
	}

	if (!dev->parent || !dev->parent->of_node)
		return -EINVAL;

	rphy->grf = syscon_node_to_regmap(dev->parent->of_node);
	if (IS_ERR(rphy->grf))
		return PTR_ERR(rphy->grf);

	if (of_property_read_u32(np, "reg", &reg)) {
		dev_err(dev, "the reg property is not assigned in %s node\n",
			np->name);
		return -EINVAL;
	}

	rphy->dev = dev;
	phy_cfgs = match->data;
	platform_set_drvdata(pdev, rphy);

	/* find out a proper config which can be matched with dt. */
	index = 0;
	while (phy_cfgs[index].reg) {
		if (phy_cfgs[index].reg == reg) {
			rphy->phy_cfg = &phy_cfgs[index];
			break;
		}

		++index;
	}

	if (!rphy->phy_cfg) {
		dev_err(dev, "no phy-config can be matched with %s node\n",
			np->name);
		return -EINVAL;
	}

	rphy->clk = of_clk_get_by_name(np, "phyclk");
	if (!IS_ERR(rphy->clk)) {
		clk_prepare_enable(rphy->clk);
	} else {
		dev_info(&pdev->dev, "no phyclk specified\n");
		rphy->clk = NULL;
	}

	ret = rockchip_usb2phy_clk480m_register(rphy);
	if (ret) {
		dev_err(dev, "failed to register 480m output clock\n");
		goto disable_clks;
	}

	index = 0;
	for_each_available_child_of_node(np, child_np) {
		struct rockchip_usb2phy_port *rport = &rphy->ports[index];
		struct phy *phy;

		/*
		 * This driver aim to support both otg-port and host-port,
		 * but unfortunately, the otg part is not ready in current,
		 * so this comments and below codes are interim, which should
		 * be changed after otg-port is supplied soon.
		 */
		if (of_node_cmp(child_np->name, "host-port"))
			goto next_child;

		phy = devm_phy_create(dev, child_np, &rockchip_usb2phy_ops);
		if (IS_ERR(phy)) {
			dev_err(dev, "failed to create phy\n");
			ret = PTR_ERR(phy);
			goto put_child;
		}

		rport->phy = phy;
		phy_set_drvdata(rport->phy, rport);

		ret = rockchip_usb2phy_host_port_init(rphy, rport, child_np);
		if (ret)
			goto put_child;

next_child:
		/* to prevent out of boundary */
		if (++index >= rphy->phy_cfg->num_ports)
			break;
	}

	provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
	return PTR_ERR_OR_ZERO(provider);

put_child:
	of_node_put(child_np);
disable_clks:
	if (rphy->clk) {
		clk_disable_unprepare(rphy->clk);
		clk_put(rphy->clk);
	}
	return ret;
}

static const struct rockchip_usb2phy_cfg rk3366_phy_cfgs[] = {
	{
		.reg = 0x700,
		.num_ports	= 2,
		.clkout_ctl	= { 0x0724, 15, 15, 1, 0 },
		.port_cfgs	= {
			[USB2PHY_PORT_HOST] = {
				.phy_sus	= { 0x0728, 15, 0, 0, 0x1d1 },
				.ls_det_en	= { 0x0680, 4, 4, 0, 1 },
				.ls_det_st	= { 0x0690, 4, 4, 0, 1 },
				.ls_det_clr	= { 0x06a0, 4, 4, 0, 1 },
				.utmi_ls	= { 0x049c, 14, 13, 0, 1 },
				.utmi_hstdet	= { 0x049c, 12, 12, 0, 1 }
			}
		},
	},
	{ /* sentinel */ }
};

static const struct rockchip_usb2phy_cfg rk3399_phy_cfgs[] = {
	{
		.reg = 0xe450,
		.num_ports	= 2,
		.clkout_ctl	= { 0xe450, 4, 4, 1, 0 },
		.port_cfgs	= {
			[USB2PHY_PORT_HOST] = {
				.phy_sus	= { 0xe458, 1, 0, 0x2, 0x1 },
				.ls_det_en	= { 0xe3c0, 6, 6, 0, 1 },
				.ls_det_st	= { 0xe3e0, 6, 6, 0, 1 },
				.ls_det_clr	= { 0xe3d0, 6, 6, 0, 1 },
				.utmi_ls	= { 0xe2ac, 22, 21, 0, 1 },
				.utmi_hstdet	= { 0xe2ac, 23, 23, 0, 1 }
			}
		},
	},
	{
		.reg = 0xe460,
		.num_ports	= 2,
		.clkout_ctl	= { 0xe460, 4, 4, 1, 0 },
		.port_cfgs	= {
			[USB2PHY_PORT_HOST] = {
				.phy_sus	= { 0xe468, 1, 0, 0x2, 0x1 },
				.ls_det_en	= { 0xe3c0, 11, 11, 0, 1 },
				.ls_det_st	= { 0xe3e0, 11, 11, 0, 1 },
				.ls_det_clr	= { 0xe3d0, 11, 11, 0, 1 },
				.utmi_ls	= { 0xe2ac, 26, 25, 0, 1 },
				.utmi_hstdet	= { 0xe2ac, 27, 27, 0, 1 }
			}
		},
	},
	{ /* sentinel */ }
};

static const struct of_device_id rockchip_usb2phy_dt_match[] = {
	{ .compatible = "rockchip,rk3366-usb2phy", .data = &rk3366_phy_cfgs },
	{ .compatible = "rockchip,rk3399-usb2phy", .data = &rk3399_phy_cfgs },
	{}
};
MODULE_DEVICE_TABLE(of, rockchip_usb2phy_dt_match);

static struct platform_driver rockchip_usb2phy_driver = {
	.probe		= rockchip_usb2phy_probe,
	.driver		= {
		.name	= "rockchip-usb2phy",
		.of_match_table = rockchip_usb2phy_dt_match,
	},
};
module_platform_driver(rockchip_usb2phy_driver);

MODULE_AUTHOR("Frank Wang <frank.wang@rock-chips.com>");
MODULE_DESCRIPTION("Rockchip USB2.0 PHY driver");
MODULE_LICENSE("GPL v2");