// SPDX-License-Identifier: GPL-2.0+
/*
 * BRIEF MODULE DESCRIPTION
 *     PCI init for Ralink RT2880 solution
 *
 * Copyright 2007 Ralink Inc. (bruce_chang@ralinktech.com.tw)
 *
 * May 2007 Bruce Chang
 * Initial Release
 *
 * May 2009 Bruce Chang
 * support RT2880/RT3883 PCIe
 *
 * May 2011 Bruce Chang
 * support RT6855/MT7620 PCIe
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_pci.h>
#include <linux/of_platform.h>
#include <linux/pci.h>
#include <linux/phy/phy.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/sys_soc.h>

/* MediaTek-specific configuration registers */
#define PCIE_FTS_NUM			0x70c
#define PCIE_FTS_NUM_MASK		GENMASK(15, 8)
#define PCIE_FTS_NUM_L0(x)		(((x) & 0xff) << 8)

/* Host-PCI bridge registers */
#define RALINK_PCI_PCICFG_ADDR		0x0000
#define RALINK_PCI_PCIMSK_ADDR		0x000c
#define RALINK_PCI_CONFIG_ADDR		0x0020
#define RALINK_PCI_CONFIG_DATA		0x0024
#define RALINK_PCI_MEMBASE		0x0028
#define RALINK_PCI_IOBASE		0x002c

/* PCIe RC control registers */
#define RALINK_PCI_ID			0x0030
#define RALINK_PCI_CLASS		0x0034
#define RALINK_PCI_SUBID		0x0038
#define RALINK_PCI_STATUS		0x0050

/* Some definition values */
#define PCIE_REVISION_ID		BIT(0)
#define PCIE_CLASS_CODE			(0x60400 << 8)
#define PCIE_BAR_MAP_MAX		GENMASK(30, 16)
#define PCIE_BAR_ENABLE			BIT(0)
#define PCIE_PORT_INT_EN(x)		BIT(20 + (x))
#define PCIE_PORT_LINKUP		BIT(0)
#define PCIE_PORT_CNT			3

#define PERST_DELAY_MS			100

/**
 * struct mt7621_pcie_port - PCIe port information
 * @base: I/O mapped register base
 * @list: port list
 * @pcie: pointer to PCIe host info
 * @clk: pointer to the port clock gate
 * @phy: pointer to PHY control block
 * @pcie_rst: pointer to port reset control
 * @gpio_rst: gpio reset
 * @slot: port slot
 * @enabled: indicates if port is enabled
 */
struct mt7621_pcie_port {
	void __iomem *base;
	struct list_head list;
	struct mt7621_pcie *pcie;
	struct clk *clk;
	struct phy *phy;
	struct reset_control *pcie_rst;
	struct gpio_desc *gpio_rst;
	u32 slot;
	bool enabled;
};

/**
 * struct mt7621_pcie - PCIe host information
 * @base: IO Mapped Register Base
 * @dev: Pointer to PCIe device
 * @ports: pointer to PCIe port information
 * @resets_inverted: depends on chip revision
 * reset lines are inverted.
 */
struct mt7621_pcie {
	struct device *dev;
	void __iomem *base;
	struct list_head ports;
	bool resets_inverted;
};

static inline u32 pcie_read(struct mt7621_pcie *pcie, u32 reg)
{
	return readl_relaxed(pcie->base + reg);
}

static inline void pcie_write(struct mt7621_pcie *pcie, u32 val, u32 reg)
{
	writel_relaxed(val, pcie->base + reg);
}

static inline void pcie_rmw(struct mt7621_pcie *pcie, u32 reg, u32 clr, u32 set)
{
	u32 val = readl_relaxed(pcie->base + reg);

	val &= ~clr;
	val |= set;
	writel_relaxed(val, pcie->base + reg);
}

static inline u32 pcie_port_read(struct mt7621_pcie_port *port, u32 reg)
{
	return readl_relaxed(port->base + reg);
}

static inline void pcie_port_write(struct mt7621_pcie_port *port,
				   u32 val, u32 reg)
{
	writel_relaxed(val, port->base + reg);
}

static inline u32 mt7621_pcie_get_cfgaddr(unsigned int bus, unsigned int slot,
					 unsigned int func, unsigned int where)
{
	return (((where & 0xf00) >> 8) << 24) | (bus << 16) | (slot << 11) |
		(func << 8) | (where & 0xfc) | 0x80000000;
}

static void __iomem *mt7621_pcie_map_bus(struct pci_bus *bus,
					 unsigned int devfn, int where)
{
	struct mt7621_pcie *pcie = bus->sysdata;
	u32 address = mt7621_pcie_get_cfgaddr(bus->number, PCI_SLOT(devfn),
					     PCI_FUNC(devfn), where);

	writel_relaxed(address, pcie->base + RALINK_PCI_CONFIG_ADDR);

	return pcie->base + RALINK_PCI_CONFIG_DATA + (where & 3);
}

static struct pci_ops mt7621_pcie_ops = {
	.map_bus	= mt7621_pcie_map_bus,
	.read		= pci_generic_config_read,
	.write		= pci_generic_config_write,
};

static u32 read_config(struct mt7621_pcie *pcie, unsigned int dev, u32 reg)
{
	u32 address = mt7621_pcie_get_cfgaddr(0, dev, 0, reg);

	pcie_write(pcie, address, RALINK_PCI_CONFIG_ADDR);
	return pcie_read(pcie, RALINK_PCI_CONFIG_DATA);
}

static void write_config(struct mt7621_pcie *pcie, unsigned int dev,
			 u32 reg, u32 val)
{
	u32 address = mt7621_pcie_get_cfgaddr(0, dev, 0, reg);

	pcie_write(pcie, address, RALINK_PCI_CONFIG_ADDR);
	pcie_write(pcie, val, RALINK_PCI_CONFIG_DATA);
}

static inline void mt7621_rst_gpio_pcie_assert(struct mt7621_pcie_port *port)
{
	if (port->gpio_rst)
		gpiod_set_value(port->gpio_rst, 1);
}

static inline void mt7621_rst_gpio_pcie_deassert(struct mt7621_pcie_port *port)
{
	if (port->gpio_rst)
		gpiod_set_value(port->gpio_rst, 0);
}

static inline bool mt7621_pcie_port_is_linkup(struct mt7621_pcie_port *port)
{
	return (pcie_port_read(port, RALINK_PCI_STATUS) & PCIE_PORT_LINKUP) != 0;
}

static inline void mt7621_control_assert(struct mt7621_pcie_port *port)
{
	struct mt7621_pcie *pcie = port->pcie;

	if (pcie->resets_inverted)
		reset_control_assert(port->pcie_rst);
	else
		reset_control_deassert(port->pcie_rst);
}

static inline void mt7621_control_deassert(struct mt7621_pcie_port *port)
{
	struct mt7621_pcie *pcie = port->pcie;

	if (pcie->resets_inverted)
		reset_control_deassert(port->pcie_rst);
	else
		reset_control_assert(port->pcie_rst);
}

static int mt7621_pcie_parse_port(struct mt7621_pcie *pcie,
				  struct device_node *node,
				  int slot)
{
	struct mt7621_pcie_port *port;
	struct device *dev = pcie->dev;
	struct platform_device *pdev = to_platform_device(dev);
	char name[10];
	int err;

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

	port->base = devm_platform_ioremap_resource(pdev, slot + 1);
	if (IS_ERR(port->base))
		return PTR_ERR(port->base);

	port->clk = devm_get_clk_from_child(dev, node, NULL);
	if (IS_ERR(port->clk)) {
		dev_err(dev, "failed to get pcie%d clock\n", slot);
		return PTR_ERR(port->clk);
	}

	port->pcie_rst = of_reset_control_get_exclusive(node, NULL);
	if (PTR_ERR(port->pcie_rst) == -EPROBE_DEFER) {
		dev_err(dev, "failed to get pcie%d reset control\n", slot);
		return PTR_ERR(port->pcie_rst);
	}

	snprintf(name, sizeof(name), "pcie-phy%d", slot);
	port->phy = devm_of_phy_get(dev, node, name);
	if (IS_ERR(port->phy)) {
		dev_err(dev, "failed to get pcie-phy%d\n", slot);
		err = PTR_ERR(port->phy);
		goto remove_reset;
	}

	port->gpio_rst = devm_gpiod_get_index_optional(dev, "reset", slot,
						       GPIOD_OUT_LOW);
	if (IS_ERR(port->gpio_rst)) {
		dev_err(dev, "failed to get GPIO for PCIe%d\n", slot);
		err = PTR_ERR(port->gpio_rst);
		goto remove_reset;
	}

	port->slot = slot;
	port->pcie = pcie;

	INIT_LIST_HEAD(&port->list);
	list_add_tail(&port->list, &pcie->ports);

	return 0;

remove_reset:
	reset_control_put(port->pcie_rst);
	return err;
}

static int mt7621_pcie_parse_dt(struct mt7621_pcie *pcie)
{
	struct device *dev = pcie->dev;
	struct platform_device *pdev = to_platform_device(dev);
	struct device_node *node = dev->of_node, *child;
	int err;

	pcie->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(pcie->base))
		return PTR_ERR(pcie->base);

	for_each_available_child_of_node(node, child) {
		int slot;

		err = of_pci_get_devfn(child);
		if (err < 0) {
			of_node_put(child);
			dev_err(dev, "failed to parse devfn: %d\n", err);
			return err;
		}

		slot = PCI_SLOT(err);

		err = mt7621_pcie_parse_port(pcie, child, slot);
		if (err) {
			of_node_put(child);
			return err;
		}
	}

	return 0;
}

static int mt7621_pcie_init_port(struct mt7621_pcie_port *port)
{
	struct mt7621_pcie *pcie = port->pcie;
	struct device *dev = pcie->dev;
	u32 slot = port->slot;
	int err;

	err = phy_init(port->phy);
	if (err) {
		dev_err(dev, "failed to initialize port%d phy\n", slot);
		return err;
	}

	err = phy_power_on(port->phy);
	if (err) {
		dev_err(dev, "failed to power on port%d phy\n", slot);
		phy_exit(port->phy);
		return err;
	}

	port->enabled = true;

	return 0;
}

static void mt7621_pcie_reset_assert(struct mt7621_pcie *pcie)
{
	struct mt7621_pcie_port *port;

	list_for_each_entry(port, &pcie->ports, list) {
		/* PCIe RC reset assert */
		mt7621_control_assert(port);

		/* PCIe EP reset assert */
		mt7621_rst_gpio_pcie_assert(port);
	}

	msleep(PERST_DELAY_MS);
}

static void mt7621_pcie_reset_rc_deassert(struct mt7621_pcie *pcie)
{
	struct mt7621_pcie_port *port;

	list_for_each_entry(port, &pcie->ports, list)
		mt7621_control_deassert(port);
}

static void mt7621_pcie_reset_ep_deassert(struct mt7621_pcie *pcie)
{
	struct mt7621_pcie_port *port;

	list_for_each_entry(port, &pcie->ports, list)
		mt7621_rst_gpio_pcie_deassert(port);

	msleep(PERST_DELAY_MS);
}

static int mt7621_pcie_init_ports(struct mt7621_pcie *pcie)
{
	struct device *dev = pcie->dev;
	struct mt7621_pcie_port *port, *tmp;
	u8 num_disabled = 0;
	int err;

	mt7621_pcie_reset_assert(pcie);
	mt7621_pcie_reset_rc_deassert(pcie);

	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
		u32 slot = port->slot;

		if (slot == 1) {
			port->enabled = true;
			continue;
		}

		err = mt7621_pcie_init_port(port);
		if (err) {
			dev_err(dev, "initializing port %d failed\n", slot);
			list_del(&port->list);
		}
	}

	mt7621_pcie_reset_ep_deassert(pcie);

	tmp = NULL;
	list_for_each_entry(port, &pcie->ports, list) {
		u32 slot = port->slot;

		if (!mt7621_pcie_port_is_linkup(port)) {
			dev_err(dev, "pcie%d no card, disable it (RST & CLK)\n",
				slot);
			mt7621_control_assert(port);
			port->enabled = false;
			num_disabled++;

			if (slot == 0) {
				tmp = port;
				continue;
			}

			if (slot == 1 && tmp && !tmp->enabled)
				phy_power_off(tmp->phy);
		}
	}

	return (num_disabled != PCIE_PORT_CNT) ? 0 : -ENODEV;
}

static void mt7621_pcie_enable_port(struct mt7621_pcie_port *port)
{
	struct mt7621_pcie *pcie = port->pcie;
	u32 slot = port->slot;
	u32 val;

	/* enable pcie interrupt */
	val = pcie_read(pcie, RALINK_PCI_PCIMSK_ADDR);
	val |= PCIE_PORT_INT_EN(slot);
	pcie_write(pcie, val, RALINK_PCI_PCIMSK_ADDR);

	/* map 2G DDR region */
	pcie_port_write(port, PCIE_BAR_MAP_MAX | PCIE_BAR_ENABLE,
			PCI_BASE_ADDRESS_0);

	/* configure class code and revision ID */
	pcie_port_write(port, PCIE_CLASS_CODE | PCIE_REVISION_ID,
			RALINK_PCI_CLASS);

	/* configure RC FTS number to 250 when it leaves L0s */
	val = read_config(pcie, slot, PCIE_FTS_NUM);
	val &= ~PCIE_FTS_NUM_MASK;
	val |= PCIE_FTS_NUM_L0(0x50);
	write_config(pcie, slot, PCIE_FTS_NUM, val);
}

static int mt7621_pcie_enable_ports(struct pci_host_bridge *host)
{
	struct mt7621_pcie *pcie = pci_host_bridge_priv(host);
	struct device *dev = pcie->dev;
	struct mt7621_pcie_port *port;
	struct resource_entry *entry;
	int err;

	entry = resource_list_first_type(&host->windows, IORESOURCE_IO);
	if (!entry) {
		dev_err(dev, "cannot get io resource\n");
		return -EINVAL;
	}

	/* Setup MEMWIN and IOWIN */
	pcie_write(pcie, 0xffffffff, RALINK_PCI_MEMBASE);
	pcie_write(pcie, entry->res->start - entry->offset, RALINK_PCI_IOBASE);

	list_for_each_entry(port, &pcie->ports, list) {
		if (port->enabled) {
			err = clk_prepare_enable(port->clk);
			if (err) {
				dev_err(dev, "enabling clk pcie%d\n",
					port->slot);
				return err;
			}

			mt7621_pcie_enable_port(port);
			dev_info(dev, "PCIE%d enabled\n", port->slot);
		}
	}

	return 0;
}

static int mt7621_pcie_register_host(struct pci_host_bridge *host)
{
	struct mt7621_pcie *pcie = pci_host_bridge_priv(host);

	host->ops = &mt7621_pcie_ops;
	host->sysdata = pcie;
	return pci_host_probe(host);
}

static const struct soc_device_attribute mt7621_pcie_quirks_match[] = {
	{ .soc_id = "mt7621", .revision = "E2" }
};

static int mt7621_pcie_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct soc_device_attribute *attr;
	struct mt7621_pcie_port *port;
	struct mt7621_pcie *pcie;
	struct pci_host_bridge *bridge;
	int err;

	if (!dev->of_node)
		return -ENODEV;

	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
	if (!bridge)
		return -ENOMEM;

	pcie = pci_host_bridge_priv(bridge);
	pcie->dev = dev;
	platform_set_drvdata(pdev, pcie);
	INIT_LIST_HEAD(&pcie->ports);

	attr = soc_device_match(mt7621_pcie_quirks_match);
	if (attr)
		pcie->resets_inverted = true;

	err = mt7621_pcie_parse_dt(pcie);
	if (err) {
		dev_err(dev, "parsing DT failed\n");
		return err;
	}

	err = mt7621_pcie_init_ports(pcie);
	if (err) {
		dev_err(dev, "nothing connected in virtual bridges\n");
		return 0;
	}

	err = mt7621_pcie_enable_ports(bridge);
	if (err) {
		dev_err(dev, "error enabling pcie ports\n");
		goto remove_resets;
	}

	return mt7621_pcie_register_host(bridge);

remove_resets:
	list_for_each_entry(port, &pcie->ports, list)
		reset_control_put(port->pcie_rst);

	return err;
}

static int mt7621_pcie_remove(struct platform_device *pdev)
{
	struct mt7621_pcie *pcie = platform_get_drvdata(pdev);
	struct mt7621_pcie_port *port;

	list_for_each_entry(port, &pcie->ports, list)
		reset_control_put(port->pcie_rst);

	return 0;
}

static const struct of_device_id mt7621_pcie_ids[] = {
	{ .compatible = "mediatek,mt7621-pci" },
	{},
};
MODULE_DEVICE_TABLE(of, mt7621_pcie_ids);

static struct platform_driver mt7621_pcie_driver = {
	.probe = mt7621_pcie_probe,
	.remove = mt7621_pcie_remove,
	.driver = {
		.name = "mt7621-pci",
		.of_match_table = of_match_ptr(mt7621_pcie_ids),
	},
};
builtin_platform_driver(mt7621_pcie_driver);

MODULE_LICENSE("GPL v2");