// SPDX-License-Identifier: GPL-2.0+
/*
 * PCIe host controller driver for Xilinx Versal CPM DMA Bridge
 *
 * (C) Copyright 2019 - 2020, Xilinx, Inc.
 */

#include <linux/bitfield.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_pci.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/pci-ecam.h>

#include "../pci.h"

/* Register definitions */
#define XILINX_CPM_PCIE_REG_IDR		0x00000E10
#define XILINX_CPM_PCIE_REG_IMR		0x00000E14
#define XILINX_CPM_PCIE_REG_PSCR	0x00000E1C
#define XILINX_CPM_PCIE_REG_RPSC	0x00000E20
#define XILINX_CPM_PCIE_REG_RPEFR	0x00000E2C
#define XILINX_CPM_PCIE_REG_IDRN	0x00000E38
#define XILINX_CPM_PCIE_REG_IDRN_MASK	0x00000E3C
#define XILINX_CPM_PCIE_MISC_IR_STATUS	0x00000340
#define XILINX_CPM_PCIE_MISC_IR_ENABLE	0x00000348
#define XILINX_CPM_PCIE_MISC_IR_LOCAL	BIT(1)

/* Interrupt registers definitions */
#define XILINX_CPM_PCIE_INTR_LINK_DOWN		0
#define XILINX_CPM_PCIE_INTR_HOT_RESET		3
#define XILINX_CPM_PCIE_INTR_CFG_PCIE_TIMEOUT	4
#define XILINX_CPM_PCIE_INTR_CFG_TIMEOUT	8
#define XILINX_CPM_PCIE_INTR_CORRECTABLE	9
#define XILINX_CPM_PCIE_INTR_NONFATAL		10
#define XILINX_CPM_PCIE_INTR_FATAL		11
#define XILINX_CPM_PCIE_INTR_CFG_ERR_POISON	12
#define XILINX_CPM_PCIE_INTR_PME_TO_ACK_RCVD	15
#define XILINX_CPM_PCIE_INTR_INTX		16
#define XILINX_CPM_PCIE_INTR_PM_PME_RCVD	17
#define XILINX_CPM_PCIE_INTR_SLV_UNSUPP		20
#define XILINX_CPM_PCIE_INTR_SLV_UNEXP		21
#define XILINX_CPM_PCIE_INTR_SLV_COMPL		22
#define XILINX_CPM_PCIE_INTR_SLV_ERRP		23
#define XILINX_CPM_PCIE_INTR_SLV_CMPABT		24
#define XILINX_CPM_PCIE_INTR_SLV_ILLBUR		25
#define XILINX_CPM_PCIE_INTR_MST_DECERR		26
#define XILINX_CPM_PCIE_INTR_MST_SLVERR		27
#define XILINX_CPM_PCIE_INTR_SLV_PCIE_TIMEOUT	28

#define IMR(x) BIT(XILINX_CPM_PCIE_INTR_ ##x)

#define XILINX_CPM_PCIE_IMR_ALL_MASK			\
	(						\
		IMR(LINK_DOWN)		|		\
		IMR(HOT_RESET)		|		\
		IMR(CFG_PCIE_TIMEOUT)	|		\
		IMR(CFG_TIMEOUT)	|		\
		IMR(CORRECTABLE)	|		\
		IMR(NONFATAL)		|		\
		IMR(FATAL)		|		\
		IMR(CFG_ERR_POISON)	|		\
		IMR(PME_TO_ACK_RCVD)	|		\
		IMR(INTX)		|		\
		IMR(PM_PME_RCVD)	|		\
		IMR(SLV_UNSUPP)		|		\
		IMR(SLV_UNEXP)		|		\
		IMR(SLV_COMPL)		|		\
		IMR(SLV_ERRP)		|		\
		IMR(SLV_CMPABT)		|		\
		IMR(SLV_ILLBUR)		|		\
		IMR(MST_DECERR)		|		\
		IMR(MST_SLVERR)		|		\
		IMR(SLV_PCIE_TIMEOUT)			\
	)

#define XILINX_CPM_PCIE_IDR_ALL_MASK		0xFFFFFFFF
#define XILINX_CPM_PCIE_IDRN_MASK		GENMASK(19, 16)
#define XILINX_CPM_PCIE_IDRN_SHIFT		16

/* Root Port Error FIFO Read Register definitions */
#define XILINX_CPM_PCIE_RPEFR_ERR_VALID		BIT(18)
#define XILINX_CPM_PCIE_RPEFR_REQ_ID		GENMASK(15, 0)
#define XILINX_CPM_PCIE_RPEFR_ALL_MASK		0xFFFFFFFF

/* Root Port Status/control Register definitions */
#define XILINX_CPM_PCIE_REG_RPSC_BEN		BIT(0)

/* Phy Status/Control Register definitions */
#define XILINX_CPM_PCIE_REG_PSCR_LNKUP		BIT(11)

/**
 * struct xilinx_cpm_pcie_port - PCIe port information
 * @reg_base: Bridge Register Base
 * @cpm_base: CPM System Level Control and Status Register(SLCR) Base
 * @dev: Device pointer
 * @intx_domain: Legacy IRQ domain pointer
 * @cpm_domain: CPM IRQ domain pointer
 * @cfg: Holds mappings of config space window
 * @intx_irq: legacy interrupt number
 * @irq: Error interrupt number
 * @lock: lock protecting shared register access
 */
struct xilinx_cpm_pcie_port {
	void __iomem			*reg_base;
	void __iomem			*cpm_base;
	struct device			*dev;
	struct irq_domain		*intx_domain;
	struct irq_domain		*cpm_domain;
	struct pci_config_window	*cfg;
	int				intx_irq;
	int				irq;
	raw_spinlock_t			lock;
};

static u32 pcie_read(struct xilinx_cpm_pcie_port *port, u32 reg)
{
	return readl_relaxed(port->reg_base + reg);
}

static void pcie_write(struct xilinx_cpm_pcie_port *port,
		       u32 val, u32 reg)
{
	writel_relaxed(val, port->reg_base + reg);
}

static bool cpm_pcie_link_up(struct xilinx_cpm_pcie_port *port)
{
	return (pcie_read(port, XILINX_CPM_PCIE_REG_PSCR) &
		XILINX_CPM_PCIE_REG_PSCR_LNKUP);
}

static void cpm_pcie_clear_err_interrupts(struct xilinx_cpm_pcie_port *port)
{
	unsigned long val = pcie_read(port, XILINX_CPM_PCIE_REG_RPEFR);

	if (val & XILINX_CPM_PCIE_RPEFR_ERR_VALID) {
		dev_dbg(port->dev, "Requester ID %lu\n",
			val & XILINX_CPM_PCIE_RPEFR_REQ_ID);
		pcie_write(port, XILINX_CPM_PCIE_RPEFR_ALL_MASK,
			   XILINX_CPM_PCIE_REG_RPEFR);
	}
}

static void xilinx_cpm_mask_leg_irq(struct irq_data *data)
{
	struct xilinx_cpm_pcie_port *port = irq_data_get_irq_chip_data(data);
	unsigned long flags;
	u32 mask;
	u32 val;

	mask = BIT(data->hwirq + XILINX_CPM_PCIE_IDRN_SHIFT);
	raw_spin_lock_irqsave(&port->lock, flags);
	val = pcie_read(port, XILINX_CPM_PCIE_REG_IDRN_MASK);
	pcie_write(port, (val & (~mask)), XILINX_CPM_PCIE_REG_IDRN_MASK);
	raw_spin_unlock_irqrestore(&port->lock, flags);
}

static void xilinx_cpm_unmask_leg_irq(struct irq_data *data)
{
	struct xilinx_cpm_pcie_port *port = irq_data_get_irq_chip_data(data);
	unsigned long flags;
	u32 mask;
	u32 val;

	mask = BIT(data->hwirq + XILINX_CPM_PCIE_IDRN_SHIFT);
	raw_spin_lock_irqsave(&port->lock, flags);
	val = pcie_read(port, XILINX_CPM_PCIE_REG_IDRN_MASK);
	pcie_write(port, (val | mask), XILINX_CPM_PCIE_REG_IDRN_MASK);
	raw_spin_unlock_irqrestore(&port->lock, flags);
}

static struct irq_chip xilinx_cpm_leg_irq_chip = {
	.name		= "INTx",
	.irq_mask	= xilinx_cpm_mask_leg_irq,
	.irq_unmask	= xilinx_cpm_unmask_leg_irq,
};

/**
 * xilinx_cpm_pcie_intx_map - Set the handler for the INTx and mark IRQ as valid
 * @domain: IRQ domain
 * @irq: Virtual IRQ number
 * @hwirq: HW interrupt number
 *
 * Return: Always returns 0.
 */
static int xilinx_cpm_pcie_intx_map(struct irq_domain *domain,
				    unsigned int irq, irq_hw_number_t hwirq)
{
	irq_set_chip_and_handler(irq, &xilinx_cpm_leg_irq_chip,
				 handle_level_irq);
	irq_set_chip_data(irq, domain->host_data);
	irq_set_status_flags(irq, IRQ_LEVEL);

	return 0;
}

/* INTx IRQ Domain operations */
static const struct irq_domain_ops intx_domain_ops = {
	.map = xilinx_cpm_pcie_intx_map,
};

static void xilinx_cpm_pcie_intx_flow(struct irq_desc *desc)
{
	struct xilinx_cpm_pcie_port *port = irq_desc_get_handler_data(desc);
	struct irq_chip *chip = irq_desc_get_chip(desc);
	unsigned long val;
	int i;

	chained_irq_enter(chip, desc);

	val = FIELD_GET(XILINX_CPM_PCIE_IDRN_MASK,
			pcie_read(port, XILINX_CPM_PCIE_REG_IDRN));

	for_each_set_bit(i, &val, PCI_NUM_INTX)
		generic_handle_irq(irq_find_mapping(port->intx_domain, i));

	chained_irq_exit(chip, desc);
}

static void xilinx_cpm_mask_event_irq(struct irq_data *d)
{
	struct xilinx_cpm_pcie_port *port = irq_data_get_irq_chip_data(d);
	u32 val;

	raw_spin_lock(&port->lock);
	val = pcie_read(port, XILINX_CPM_PCIE_REG_IMR);
	val &= ~BIT(d->hwirq);
	pcie_write(port, val, XILINX_CPM_PCIE_REG_IMR);
	raw_spin_unlock(&port->lock);
}

static void xilinx_cpm_unmask_event_irq(struct irq_data *d)
{
	struct xilinx_cpm_pcie_port *port = irq_data_get_irq_chip_data(d);
	u32 val;

	raw_spin_lock(&port->lock);
	val = pcie_read(port, XILINX_CPM_PCIE_REG_IMR);
	val |= BIT(d->hwirq);
	pcie_write(port, val, XILINX_CPM_PCIE_REG_IMR);
	raw_spin_unlock(&port->lock);
}

static struct irq_chip xilinx_cpm_event_irq_chip = {
	.name		= "RC-Event",
	.irq_mask	= xilinx_cpm_mask_event_irq,
	.irq_unmask	= xilinx_cpm_unmask_event_irq,
};

static int xilinx_cpm_pcie_event_map(struct irq_domain *domain,
				     unsigned int irq, irq_hw_number_t hwirq)
{
	irq_set_chip_and_handler(irq, &xilinx_cpm_event_irq_chip,
				 handle_level_irq);
	irq_set_chip_data(irq, domain->host_data);
	irq_set_status_flags(irq, IRQ_LEVEL);
	return 0;
}

static const struct irq_domain_ops event_domain_ops = {
	.map = xilinx_cpm_pcie_event_map,
};

static void xilinx_cpm_pcie_event_flow(struct irq_desc *desc)
{
	struct xilinx_cpm_pcie_port *port = irq_desc_get_handler_data(desc);
	struct irq_chip *chip = irq_desc_get_chip(desc);
	unsigned long val;
	int i;

	chained_irq_enter(chip, desc);
	val =  pcie_read(port, XILINX_CPM_PCIE_REG_IDR);
	val &= pcie_read(port, XILINX_CPM_PCIE_REG_IMR);
	for_each_set_bit(i, &val, 32)
		generic_handle_irq(irq_find_mapping(port->cpm_domain, i));
	pcie_write(port, val, XILINX_CPM_PCIE_REG_IDR);

	/*
	 * XILINX_CPM_PCIE_MISC_IR_STATUS register is mapped to
	 * CPM SLCR block.
	 */
	val = readl_relaxed(port->cpm_base + XILINX_CPM_PCIE_MISC_IR_STATUS);
	if (val)
		writel_relaxed(val,
			       port->cpm_base + XILINX_CPM_PCIE_MISC_IR_STATUS);

	chained_irq_exit(chip, desc);
}

#define _IC(x, s)                              \
	[XILINX_CPM_PCIE_INTR_ ## x] = { __stringify(x), s }

static const struct {
	const char      *sym;
	const char      *str;
} intr_cause[32] = {
	_IC(LINK_DOWN,		"Link Down"),
	_IC(HOT_RESET,		"Hot reset"),
	_IC(CFG_TIMEOUT,	"ECAM access timeout"),
	_IC(CORRECTABLE,	"Correctable error message"),
	_IC(NONFATAL,		"Non fatal error message"),
	_IC(FATAL,		"Fatal error message"),
	_IC(SLV_UNSUPP,		"Slave unsupported request"),
	_IC(SLV_UNEXP,		"Slave unexpected completion"),
	_IC(SLV_COMPL,		"Slave completion timeout"),
	_IC(SLV_ERRP,		"Slave Error Poison"),
	_IC(SLV_CMPABT,		"Slave Completer Abort"),
	_IC(SLV_ILLBUR,		"Slave Illegal Burst"),
	_IC(MST_DECERR,		"Master decode error"),
	_IC(MST_SLVERR,		"Master slave error"),
	_IC(CFG_PCIE_TIMEOUT,	"PCIe ECAM access timeout"),
	_IC(CFG_ERR_POISON,	"ECAM poisoned completion received"),
	_IC(PME_TO_ACK_RCVD,	"PME_TO_ACK message received"),
	_IC(PM_PME_RCVD,	"PM_PME message received"),
	_IC(SLV_PCIE_TIMEOUT,	"PCIe completion timeout received"),
};

static irqreturn_t xilinx_cpm_pcie_intr_handler(int irq, void *dev_id)
{
	struct xilinx_cpm_pcie_port *port = dev_id;
	struct device *dev = port->dev;
	struct irq_data *d;

	d = irq_domain_get_irq_data(port->cpm_domain, irq);

	switch (d->hwirq) {
	case XILINX_CPM_PCIE_INTR_CORRECTABLE:
	case XILINX_CPM_PCIE_INTR_NONFATAL:
	case XILINX_CPM_PCIE_INTR_FATAL:
		cpm_pcie_clear_err_interrupts(port);
		fallthrough;

	default:
		if (intr_cause[d->hwirq].str)
			dev_warn(dev, "%s\n", intr_cause[d->hwirq].str);
		else
			dev_warn(dev, "Unknown IRQ %ld\n", d->hwirq);
	}

	return IRQ_HANDLED;
}

static void xilinx_cpm_free_irq_domains(struct xilinx_cpm_pcie_port *port)
{
	if (port->intx_domain) {
		irq_domain_remove(port->intx_domain);
		port->intx_domain = NULL;
	}

	if (port->cpm_domain) {
		irq_domain_remove(port->cpm_domain);
		port->cpm_domain = NULL;
	}
}

/**
 * xilinx_cpm_pcie_init_irq_domain - Initialize IRQ domain
 * @port: PCIe port information
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_cpm_pcie_init_irq_domain(struct xilinx_cpm_pcie_port *port)
{
	struct device *dev = port->dev;
	struct device_node *node = dev->of_node;
	struct device_node *pcie_intc_node;

	/* Setup INTx */
	pcie_intc_node = of_get_next_child(node, NULL);
	if (!pcie_intc_node) {
		dev_err(dev, "No PCIe Intc node found\n");
		return -EINVAL;
	}

	port->cpm_domain = irq_domain_add_linear(pcie_intc_node, 32,
						 &event_domain_ops,
						 port);
	if (!port->cpm_domain)
		goto out;

	irq_domain_update_bus_token(port->cpm_domain, DOMAIN_BUS_NEXUS);

	port->intx_domain = irq_domain_add_linear(pcie_intc_node, PCI_NUM_INTX,
						  &intx_domain_ops,
						  port);
	if (!port->intx_domain)
		goto out;

	irq_domain_update_bus_token(port->intx_domain, DOMAIN_BUS_WIRED);

	of_node_put(pcie_intc_node);
	raw_spin_lock_init(&port->lock);

	return 0;
out:
	xilinx_cpm_free_irq_domains(port);
	of_node_put(pcie_intc_node);
	dev_err(dev, "Failed to allocate IRQ domains\n");

	return -ENOMEM;
}

static int xilinx_cpm_setup_irq(struct xilinx_cpm_pcie_port *port)
{
	struct device *dev = port->dev;
	struct platform_device *pdev = to_platform_device(dev);
	int i, irq;

	port->irq = platform_get_irq(pdev, 0);
	if (port->irq < 0)
		return port->irq;

	for (i = 0; i < ARRAY_SIZE(intr_cause); i++) {
		int err;

		if (!intr_cause[i].str)
			continue;

		irq = irq_create_mapping(port->cpm_domain, i);
		if (!irq) {
			dev_err(dev, "Failed to map interrupt\n");
			return -ENXIO;
		}

		err = devm_request_irq(dev, irq, xilinx_cpm_pcie_intr_handler,
				       0, intr_cause[i].sym, port);
		if (err) {
			dev_err(dev, "Failed to request IRQ %d\n", irq);
			return err;
		}
	}

	port->intx_irq = irq_create_mapping(port->cpm_domain,
					    XILINX_CPM_PCIE_INTR_INTX);
	if (!port->intx_irq) {
		dev_err(dev, "Failed to map INTx interrupt\n");
		return -ENXIO;
	}

	/* Plug the INTx chained handler */
	irq_set_chained_handler_and_data(port->intx_irq,
					 xilinx_cpm_pcie_intx_flow, port);

	/* Plug the main event chained handler */
	irq_set_chained_handler_and_data(port->irq,
					 xilinx_cpm_pcie_event_flow, port);

	return 0;
}

/**
 * xilinx_cpm_pcie_init_port - Initialize hardware
 * @port: PCIe port information
 */
static void xilinx_cpm_pcie_init_port(struct xilinx_cpm_pcie_port *port)
{
	if (cpm_pcie_link_up(port))
		dev_info(port->dev, "PCIe Link is UP\n");
	else
		dev_info(port->dev, "PCIe Link is DOWN\n");

	/* Disable all interrupts */
	pcie_write(port, ~XILINX_CPM_PCIE_IDR_ALL_MASK,
		   XILINX_CPM_PCIE_REG_IMR);

	/* Clear pending interrupts */
	pcie_write(port, pcie_read(port, XILINX_CPM_PCIE_REG_IDR) &
		   XILINX_CPM_PCIE_IMR_ALL_MASK,
		   XILINX_CPM_PCIE_REG_IDR);

	/*
	 * XILINX_CPM_PCIE_MISC_IR_ENABLE register is mapped to
	 * CPM SLCR block.
	 */
	writel(XILINX_CPM_PCIE_MISC_IR_LOCAL,
	       port->cpm_base + XILINX_CPM_PCIE_MISC_IR_ENABLE);
	/* Enable the Bridge enable bit */
	pcie_write(port, pcie_read(port, XILINX_CPM_PCIE_REG_RPSC) |
		   XILINX_CPM_PCIE_REG_RPSC_BEN,
		   XILINX_CPM_PCIE_REG_RPSC);
}

/**
 * xilinx_cpm_pcie_parse_dt - Parse Device tree
 * @port: PCIe port information
 * @bus_range: Bus resource
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_cpm_pcie_parse_dt(struct xilinx_cpm_pcie_port *port,
				    struct resource *bus_range)
{
	struct device *dev = port->dev;
	struct platform_device *pdev = to_platform_device(dev);
	struct resource *res;

	port->cpm_base = devm_platform_ioremap_resource_byname(pdev,
							       "cpm_slcr");
	if (IS_ERR(port->cpm_base))
		return PTR_ERR(port->cpm_base);

	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
	if (!res)
		return -ENXIO;

	port->cfg = pci_ecam_create(dev, res, bus_range,
				    &pci_generic_ecam_ops);
	if (IS_ERR(port->cfg))
		return PTR_ERR(port->cfg);

	port->reg_base = port->cfg->win;

	return 0;
}

static void xilinx_cpm_free_interrupts(struct xilinx_cpm_pcie_port *port)
{
	irq_set_chained_handler_and_data(port->intx_irq, NULL, NULL);
	irq_set_chained_handler_and_data(port->irq, NULL, NULL);
}

/**
 * xilinx_cpm_pcie_probe - Probe function
 * @pdev: Platform device pointer
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_cpm_pcie_probe(struct platform_device *pdev)
{
	struct xilinx_cpm_pcie_port *port;
	struct device *dev = &pdev->dev;
	struct pci_host_bridge *bridge;
	struct resource_entry *bus;
	int err;

	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*port));
	if (!bridge)
		return -ENODEV;

	port = pci_host_bridge_priv(bridge);

	port->dev = dev;

	err = xilinx_cpm_pcie_init_irq_domain(port);
	if (err)
		return err;

	bus = resource_list_first_type(&bridge->windows, IORESOURCE_BUS);
	if (!bus)
		return -ENODEV;

	err = xilinx_cpm_pcie_parse_dt(port, bus->res);
	if (err) {
		dev_err(dev, "Parsing DT failed\n");
		goto err_parse_dt;
	}

	xilinx_cpm_pcie_init_port(port);

	err = xilinx_cpm_setup_irq(port);
	if (err) {
		dev_err(dev, "Failed to set up interrupts\n");
		goto err_setup_irq;
	}

	bridge->sysdata = port->cfg;
	bridge->ops = (struct pci_ops *)&pci_generic_ecam_ops.pci_ops;

	err = pci_host_probe(bridge);
	if (err < 0)
		goto err_host_bridge;

	return 0;

err_host_bridge:
	xilinx_cpm_free_interrupts(port);
err_setup_irq:
	pci_ecam_free(port->cfg);
err_parse_dt:
	xilinx_cpm_free_irq_domains(port);
	return err;
}

static const struct of_device_id xilinx_cpm_pcie_of_match[] = {
	{ .compatible = "xlnx,versal-cpm-host-1.00", },
	{}
};

static struct platform_driver xilinx_cpm_pcie_driver = {
	.driver = {
		.name = "xilinx-cpm-pcie",
		.of_match_table = xilinx_cpm_pcie_of_match,
		.suppress_bind_attrs = true,
	},
	.probe = xilinx_cpm_pcie_probe,
};

builtin_platform_driver(xilinx_cpm_pcie_driver);