/*
 * PCIe host controller driver for Xilinx AXI PCIe Bridge
 *
 * Copyright (c) 2012 - 2014 Xilinx, Inc.
 *
 * Based on the Tegra PCIe driver
 *
 * Bits taken from Synopsys Designware Host controller driver and
 * ARM PCI Host generic driver.
 *
 * 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.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/msi.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>

/* Register definitions */
#define XILINX_PCIE_REG_BIR             0x00000130
#define XILINX_PCIE_REG_IDR             0x00000138
#define XILINX_PCIE_REG_IMR             0x0000013c
#define XILINX_PCIE_REG_PSCR            0x00000144
#define XILINX_PCIE_REG_RPSC            0x00000148
#define XILINX_PCIE_REG_MSIBASE1        0x0000014c
#define XILINX_PCIE_REG_MSIBASE2        0x00000150
#define XILINX_PCIE_REG_RPEFR           0x00000154
#define XILINX_PCIE_REG_RPIFR1          0x00000158
#define XILINX_PCIE_REG_RPIFR2          0x0000015c

/* Interrupt registers definitions */
#define XILINX_PCIE_INTR_LINK_DOWN      BIT(0)
#define XILINX_PCIE_INTR_ECRC_ERR       BIT(1)
#define XILINX_PCIE_INTR_STR_ERR        BIT(2)
#define XILINX_PCIE_INTR_HOT_RESET      BIT(3)
#define XILINX_PCIE_INTR_CFG_TIMEOUT    BIT(8)
#define XILINX_PCIE_INTR_CORRECTABLE    BIT(9)
#define XILINX_PCIE_INTR_NONFATAL       BIT(10)
#define XILINX_PCIE_INTR_FATAL          BIT(11)
#define XILINX_PCIE_INTR_INTX           BIT(16)
#define XILINX_PCIE_INTR_MSI            BIT(17)
#define XILINX_PCIE_INTR_SLV_UNSUPP     BIT(20)
#define XILINX_PCIE_INTR_SLV_UNEXP      BIT(21)
#define XILINX_PCIE_INTR_SLV_COMPL      BIT(22)
#define XILINX_PCIE_INTR_SLV_ERRP       BIT(23)
#define XILINX_PCIE_INTR_SLV_CMPABT     BIT(24)
#define XILINX_PCIE_INTR_SLV_ILLBUR     BIT(25)
#define XILINX_PCIE_INTR_MST_DECERR     BIT(26)
#define XILINX_PCIE_INTR_MST_SLVERR     BIT(27)
#define XILINX_PCIE_INTR_MST_ERRP       BIT(28)
#define XILINX_PCIE_IMR_ALL_MASK        0x1FF30FED
#define XILINX_PCIE_IDR_ALL_MASK        0xFFFFFFFF

/* Root Port Error FIFO Read Register definitions */
#define XILINX_PCIE_RPEFR_ERR_VALID     BIT(18)
#define XILINX_PCIE_RPEFR_REQ_ID        GENMASK(15, 0)
#define XILINX_PCIE_RPEFR_ALL_MASK      0xFFFFFFFF

/* Root Port Interrupt FIFO Read Register 1 definitions */
#define XILINX_PCIE_RPIFR1_INTR_VALID   BIT(31)
#define XILINX_PCIE_RPIFR1_MSI_INTR     BIT(30)
#define XILINX_PCIE_RPIFR1_INTR_MASK    GENMASK(28, 27)
#define XILINX_PCIE_RPIFR1_ALL_MASK     0xFFFFFFFF
#define XILINX_PCIE_RPIFR1_INTR_SHIFT   27

/* Bridge Info Register definitions */
#define XILINX_PCIE_BIR_ECAM_SZ_MASK    GENMASK(18, 16)
#define XILINX_PCIE_BIR_ECAM_SZ_SHIFT   16

/* Root Port Interrupt FIFO Read Register 2 definitions */
#define XILINX_PCIE_RPIFR2_MSG_DATA     GENMASK(15, 0)

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

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

/* ECAM definitions */
#define ECAM_BUS_NUM_SHIFT              20
#define ECAM_DEV_NUM_SHIFT              12

/* Number of MSI IRQs */
#define XILINX_NUM_MSI_IRQS             128

/* Number of Memory Resources */
#define XILINX_MAX_NUM_RESOURCES        3

/**
 * struct xilinx_pcie_port - PCIe port information
 * @reg_base: IO Mapped Register Base
 * @irq: Interrupt number
 * @msi_pages: MSI pages
 * @root_busno: Root Bus number
 * @dev: Device pointer
 * @irq_domain: IRQ domain pointer
 * @bus_range: Bus range
 * @resources: Bus Resources
 */
struct xilinx_pcie_port {
        void __iomem *reg_base;
        u32 irq;
        unsigned long msi_pages;
        u8 root_busno;
        struct device *dev;
        struct irq_domain *irq_domain;
        struct resource bus_range;
        struct list_head resources;
};

static DECLARE_BITMAP(msi_irq_in_use, XILINX_NUM_MSI_IRQS);

static inline struct xilinx_pcie_port *sys_to_pcie(struct pci_sys_data *sys)
{
        return sys->private_data;
}

static inline u32 pcie_read(struct xilinx_pcie_port *port, u32 reg)
{
        return readl(port->reg_base + reg);
}

static inline void pcie_write(struct xilinx_pcie_port *port, u32 val, u32 reg)
{
        writel(val, port->reg_base + reg);
}

static inline bool xilinx_pcie_link_is_up(struct xilinx_pcie_port *port)
{
        return (pcie_read(port, XILINX_PCIE_REG_PSCR) &
                XILINX_PCIE_REG_PSCR_LNKUP) ? 1 : 0;
}

/**
 * xilinx_pcie_clear_err_interrupts - Clear Error Interrupts
 * @port: PCIe port information
 */
static void xilinx_pcie_clear_err_interrupts(struct xilinx_pcie_port *port)
{
        u32 val = pcie_read(port, XILINX_PCIE_REG_RPEFR);

        if (val & XILINX_PCIE_RPEFR_ERR_VALID) {
                dev_dbg(port->dev, "Requester ID %d\n",
                        val & XILINX_PCIE_RPEFR_REQ_ID);
                pcie_write(port, XILINX_PCIE_RPEFR_ALL_MASK,
                           XILINX_PCIE_REG_RPEFR);
        }
}

/**
 * xilinx_pcie_valid_device - Check if a valid device is present on bus
 * @bus: PCI Bus structure
 * @devfn: device/function
 *
 * Return: 'true' on success and 'false' if invalid device is found
 */
static bool xilinx_pcie_valid_device(struct pci_bus *bus, unsigned int devfn)
{
        struct xilinx_pcie_port *port = sys_to_pcie(bus->sysdata);

        /* Check if link is up when trying to access downstream ports */
        if (bus->number != port->root_busno)
                if (!xilinx_pcie_link_is_up(port))
                        return false;

        /* Only one device down on each root port */
        if (bus->number == port->root_busno && devfn > 0)
                return false;

        /*
         * Do not read more than one device on the bus directly attached
         * to RC.
         */
        if (bus->primary == port->root_busno && devfn > 0)
                return false;

        return true;
}

/**
 * xilinx_pcie_config_base - Get configuration base
 * @bus: PCI Bus structure
 * @devfn: Device/function
 * @where: Offset from base
 *
 * Return: Base address of the configuration space needed to be
 *         accessed.
 */
static void __iomem *xilinx_pcie_config_base(struct pci_bus *bus,
                                             unsigned int devfn, int where)
{
        struct xilinx_pcie_port *port = sys_to_pcie(bus->sysdata);
        int relbus;

        relbus = (bus->number << ECAM_BUS_NUM_SHIFT) |
                 (devfn << ECAM_DEV_NUM_SHIFT);

        return port->reg_base + relbus + where;
}

/**
 * xilinx_pcie_read_config - Read configuration space
 * @bus: PCI Bus structure
 * @devfn: Device/function
 * @where: Offset from base
 * @size: Byte/word/dword
 * @val: Value to be read
 *
 * Return: PCIBIOS_SUCCESSFUL on success
 *         PCIBIOS_DEVICE_NOT_FOUND on failure
 */
static int xilinx_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
                                   int where, int size, u32 *val)
{
        void __iomem *addr;

        if (!xilinx_pcie_valid_device(bus, devfn)) {
                *val = 0xFFFFFFFF;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }

        addr = xilinx_pcie_config_base(bus, devfn, where);

        switch (size) {
        case 1:
                *val = readb(addr);
                break;
        case 2:
                *val = readw(addr);
                break;
        default:
                *val = readl(addr);
                break;
        }

        return PCIBIOS_SUCCESSFUL;
}

/**
 * xilinx_pcie_write_config - Write configuration space
 * @bus: PCI Bus structure
 * @devfn: Device/function
 * @where: Offset from base
 * @size: Byte/word/dword
 * @val: Value to be written to device
 *
 * Return: PCIBIOS_SUCCESSFUL on success
 *         PCIBIOS_DEVICE_NOT_FOUND on failure
 */
static int xilinx_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
                                    int where, int size, u32 val)
{
        void __iomem *addr;

        if (!xilinx_pcie_valid_device(bus, devfn))
                return PCIBIOS_DEVICE_NOT_FOUND;

        addr = xilinx_pcie_config_base(bus, devfn, where);

        switch (size) {
        case 1:
                writeb(val, addr);
                break;
        case 2:
                writew(val, addr);
                break;
        default:
                writel(val, addr);
                break;
        }

        return PCIBIOS_SUCCESSFUL;
}

/* PCIe operations */
static struct pci_ops xilinx_pcie_ops = {
        .read  = xilinx_pcie_read_config,
        .write = xilinx_pcie_write_config,
};

/* MSI functions */

/**
 * xilinx_pcie_destroy_msi - Free MSI number
 * @irq: IRQ to be freed
 */
static void xilinx_pcie_destroy_msi(unsigned int irq)
{
        struct irq_desc *desc;
        struct msi_desc *msi;
        struct xilinx_pcie_port *port;

        desc = irq_to_desc(irq);
        msi = irq_desc_get_msi_desc(desc);
        port = sys_to_pcie(msi->dev->bus->sysdata);

        if (!test_bit(irq, msi_irq_in_use))
                dev_err(port->dev, "Trying to free unused MSI#%d\n", irq);
        else
                clear_bit(irq, msi_irq_in_use);
}

/**
 * xilinx_pcie_assign_msi - Allocate MSI number
 * @port: PCIe port structure
 *
 * Return: A valid IRQ on success and error value on failure.
 */
static int xilinx_pcie_assign_msi(struct xilinx_pcie_port *port)
{
        int pos;

        pos = find_first_zero_bit(msi_irq_in_use, XILINX_NUM_MSI_IRQS);
        if (pos < XILINX_NUM_MSI_IRQS)
                set_bit(pos, msi_irq_in_use);
        else
                return -ENOSPC;

        return pos;
}

/**
 * xilinx_msi_teardown_irq - Destroy the MSI
 * @chip: MSI Chip descriptor
 * @irq: MSI IRQ to destroy
 */
static void xilinx_msi_teardown_irq(struct msi_chip *chip, unsigned int irq)
{
        xilinx_pcie_destroy_msi(irq);
}

/**
 * xilinx_pcie_msi_setup_irq - Setup MSI request
 * @chip: MSI chip pointer
 * @pdev: PCIe device pointer
 * @desc: MSI descriptor pointer
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_pcie_msi_setup_irq(struct msi_chip *chip,
                                     struct pci_dev *pdev,
                                     struct msi_desc *desc)
{
        struct xilinx_pcie_port *port = sys_to_pcie(pdev->bus->sysdata);
        unsigned int irq;
        int hwirq;
        struct msi_msg msg;
        phys_addr_t msg_addr;

        hwirq = xilinx_pcie_assign_msi(port);
        if (hwirq < 0)
                return hwirq;

        irq = irq_create_mapping(port->irq_domain, hwirq);
        if (!irq)
                return -EINVAL;

        irq_set_msi_desc(irq, desc);

        msg_addr = virt_to_phys((void *)port->msi_pages);

        msg.address_hi = 0;
        msg.address_lo = msg_addr;
        msg.data = irq;

        write_msi_msg(irq, &msg);

        return 0;
}

/* MSI Chip Descriptor */
static struct msi_chip xilinx_pcie_msi_chip = {
        .setup_irq = xilinx_pcie_msi_setup_irq,
        .teardown_irq = xilinx_msi_teardown_irq,
};

/* HW Interrupt Chip Descriptor */
static struct irq_chip xilinx_msi_irq_chip = {
        .name = "Xilinx PCIe MSI",
        .irq_enable = unmask_msi_irq,
        .irq_disable = mask_msi_irq,
        .irq_mask = mask_msi_irq,
        .irq_unmask = unmask_msi_irq,
};

/**
 * xilinx_pcie_msi_map - Set the handler for the MSI and mark IRQ as valid
 * @domain: IRQ domain
 * @irq: Virtual IRQ number
 * @hwirq: HW interrupt number
 *
 * Return: Always returns 0.
 */
static int xilinx_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
                               irq_hw_number_t hwirq)
{
        irq_set_chip_and_handler(irq, &xilinx_msi_irq_chip, handle_simple_irq);
        irq_set_chip_data(irq, domain->host_data);
        set_irq_flags(irq, IRQF_VALID);

        return 0;
}

/* IRQ Domain operations */
static const struct irq_domain_ops msi_domain_ops = {
        .map = xilinx_pcie_msi_map,
};

/**
 * xilinx_pcie_enable_msi - Enable MSI support
 * @port: PCIe port information
 */
static void xilinx_pcie_enable_msi(struct xilinx_pcie_port *port)
{
        phys_addr_t msg_addr;

        port->msi_pages = __get_free_pages(GFP_KERNEL, 0);
        msg_addr = virt_to_phys((void *)port->msi_pages);
        pcie_write(port, 0x0, XILINX_PCIE_REG_MSIBASE1);
        pcie_write(port, msg_addr, XILINX_PCIE_REG_MSIBASE2);
}

/**
 * xilinx_pcie_add_bus - Add MSI chip info to PCIe bus
 * @bus: PCIe bus
 */
static void xilinx_pcie_add_bus(struct pci_bus *bus)
{
        if (IS_ENABLED(CONFIG_PCI_MSI)) {
                struct xilinx_pcie_port *port = sys_to_pcie(bus->sysdata);

                xilinx_pcie_msi_chip.dev = port->dev;
                bus->msi = &xilinx_pcie_msi_chip;
        }
}

/* INTx Functions */

/**
 * xilinx_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_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
                                irq_hw_number_t hwirq)
{
        irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_simple_irq);
        irq_set_chip_data(irq, domain->host_data);
        set_irq_flags(irq, IRQF_VALID);

        return 0;
}

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

/* PCIe HW Functions */

/**
 * xilinx_pcie_intr_handler - Interrupt Service Handler
 * @irq: IRQ number
 * @data: PCIe port information
 *
 * Return: IRQ_HANDLED on success and IRQ_NONE on failure
 */
static irqreturn_t xilinx_pcie_intr_handler(int irq, void *data)
{
        struct xilinx_pcie_port *port = (struct xilinx_pcie_port *)data;
        u32 val, mask, status, msi_data;

        /* Read interrupt decode and mask registers */
        val = pcie_read(port, XILINX_PCIE_REG_IDR);
        mask = pcie_read(port, XILINX_PCIE_REG_IMR);

        status = val & mask;
        if (!status)
                return IRQ_NONE;

        if (status & XILINX_PCIE_INTR_LINK_DOWN)
                dev_warn(port->dev, "Link Down\n");

        if (status & XILINX_PCIE_INTR_ECRC_ERR)
                dev_warn(port->dev, "ECRC failed\n");

        if (status & XILINX_PCIE_INTR_STR_ERR)
                dev_warn(port->dev, "Streaming error\n");

        if (status & XILINX_PCIE_INTR_HOT_RESET)
                dev_info(port->dev, "Hot reset\n");

        if (status & XILINX_PCIE_INTR_CFG_TIMEOUT)
                dev_warn(port->dev, "ECAM access timeout\n");

        if (status & XILINX_PCIE_INTR_CORRECTABLE) {
                dev_warn(port->dev, "Correctable error message\n");
                xilinx_pcie_clear_err_interrupts(port);
        }

        if (status & XILINX_PCIE_INTR_NONFATAL) {
                dev_warn(port->dev, "Non fatal error message\n");
                xilinx_pcie_clear_err_interrupts(port);
        }

        if (status & XILINX_PCIE_INTR_FATAL) {
                dev_warn(port->dev, "Fatal error message\n");
                xilinx_pcie_clear_err_interrupts(port);
        }

        if (status & XILINX_PCIE_INTR_INTX) {
                /* INTx interrupt received */
                val = pcie_read(port, XILINX_PCIE_REG_RPIFR1);

                /* Check whether interrupt valid */
                if (!(val & XILINX_PCIE_RPIFR1_INTR_VALID)) {
                        dev_warn(port->dev, "RP Intr FIFO1 read error\n");
                        return IRQ_HANDLED;
                }

                /* Clear interrupt FIFO register 1 */
                pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
                           XILINX_PCIE_REG_RPIFR1);

                /* Handle INTx Interrupt */
                val = ((val & XILINX_PCIE_RPIFR1_INTR_MASK) >>
                        XILINX_PCIE_RPIFR1_INTR_SHIFT) + 1;
                generic_handle_irq(irq_find_mapping(port->irq_domain, val));
        }

        if (status & XILINX_PCIE_INTR_MSI) {
                /* MSI Interrupt */
                val = pcie_read(port, XILINX_PCIE_REG_RPIFR1);

                if (!(val & XILINX_PCIE_RPIFR1_INTR_VALID)) {
                        dev_warn(port->dev, "RP Intr FIFO1 read error\n");
                        return IRQ_HANDLED;
                }

                if (val & XILINX_PCIE_RPIFR1_MSI_INTR) {
                        msi_data = pcie_read(port, XILINX_PCIE_REG_RPIFR2) &
                                   XILINX_PCIE_RPIFR2_MSG_DATA;

                        /* Clear interrupt FIFO register 1 */
                        pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
                                   XILINX_PCIE_REG_RPIFR1);

                        if (IS_ENABLED(CONFIG_PCI_MSI)) {
                                /* Handle MSI Interrupt */
                                generic_handle_irq(msi_data);
                        }
                }
        }

        if (status & XILINX_PCIE_INTR_SLV_UNSUPP)
                dev_warn(port->dev, "Slave unsupported request\n");

        if (status & XILINX_PCIE_INTR_SLV_UNEXP)
                dev_warn(port->dev, "Slave unexpected completion\n");

        if (status & XILINX_PCIE_INTR_SLV_COMPL)
                dev_warn(port->dev, "Slave completion timeout\n");

        if (status & XILINX_PCIE_INTR_SLV_ERRP)
                dev_warn(port->dev, "Slave Error Poison\n");

        if (status & XILINX_PCIE_INTR_SLV_CMPABT)
                dev_warn(port->dev, "Slave Completer Abort\n");

        if (status & XILINX_PCIE_INTR_SLV_ILLBUR)
                dev_warn(port->dev, "Slave Illegal Burst\n");

        if (status & XILINX_PCIE_INTR_MST_DECERR)
                dev_warn(port->dev, "Master decode error\n");

        if (status & XILINX_PCIE_INTR_MST_SLVERR)
                dev_warn(port->dev, "Master slave error\n");

        if (status & XILINX_PCIE_INTR_MST_ERRP)
                dev_warn(port->dev, "Master error poison\n");

        /* Clear the Interrupt Decode register */
        pcie_write(port, status, XILINX_PCIE_REG_IDR);

        return IRQ_HANDLED;
}

/**
 * xilinx_pcie_free_irq_domain - Free IRQ domain
 * @port: PCIe port information
 */
static void xilinx_pcie_free_irq_domain(struct xilinx_pcie_port *port)
{
        int i;
        u32 irq, num_irqs;

        /* Free IRQ Domain */
        if (IS_ENABLED(CONFIG_PCI_MSI)) {

                free_pages(port->msi_pages, 0);

                num_irqs = XILINX_NUM_MSI_IRQS;
        } else {
                /* INTx */
                num_irqs = 4;
        }

        for (i = 0; i < num_irqs; i++) {
                irq = irq_find_mapping(port->irq_domain, i);
                if (irq > 0)
                        irq_dispose_mapping(irq);
        }

        irq_domain_remove(port->irq_domain);
}

/**
 * xilinx_pcie_init_irq_domain - Initialize IRQ domain
 * @port: PCIe port information
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_pcie_init_irq_domain(struct xilinx_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 PTR_ERR(pcie_intc_node);
        }

        port->irq_domain = irq_domain_add_linear(pcie_intc_node, 4,
                                                 &intx_domain_ops,
                                                 port);
        if (!port->irq_domain) {
                dev_err(dev, "Failed to get a INTx IRQ domain\n");
                return PTR_ERR(port->irq_domain);
        }

        /* Setup MSI */
        if (IS_ENABLED(CONFIG_PCI_MSI)) {
                port->irq_domain = irq_domain_add_linear(node,
                                                         XILINX_NUM_MSI_IRQS,
                                                         &msi_domain_ops,
                                                         &xilinx_pcie_msi_chip);
                if (!port->irq_domain) {
                        dev_err(dev, "Failed to get a MSI IRQ domain\n");
                        return PTR_ERR(port->irq_domain);
                }

                xilinx_pcie_enable_msi(port);
        }

        return 0;
}

/**
 * xilinx_pcie_init_port - Initialize hardware
 * @port: PCIe port information
 */
static void xilinx_pcie_init_port(struct xilinx_pcie_port *port)
{
        if (xilinx_pcie_link_is_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_PCIE_IDR_ALL_MASK,
                   XILINX_PCIE_REG_IMR);

        /* Clear pending interrupts */
        pcie_write(port, pcie_read(port, XILINX_PCIE_REG_IDR) &
                         XILINX_PCIE_IMR_ALL_MASK,
                   XILINX_PCIE_REG_IDR);

        /* Enable all interrupts */
        pcie_write(port, XILINX_PCIE_IMR_ALL_MASK, XILINX_PCIE_REG_IMR);

        /* Enable the Bridge enable bit */
        pcie_write(port, pcie_read(port, XILINX_PCIE_REG_RPSC) |
                         XILINX_PCIE_REG_RPSC_BEN,
                   XILINX_PCIE_REG_RPSC);
}

/**
 * xilinx_pcie_setup - Setup memory resources
 * @nr: Bus number
 * @sys: Per controller structure
 *
 * Return: '1' on success and error value on failure
 */
static int xilinx_pcie_setup(int nr, struct pci_sys_data *sys)
{
        struct xilinx_pcie_port *port = sys_to_pcie(sys);

        list_splice_init(&port->resources, &sys->resources);

        return 1;
}

/**
 * xilinx_pcie_scan_bus - Scan PCIe bus for devices
 * @nr: Bus number
 * @sys: Per controller structure
 *
 * Return: Valid Bus pointer on success and NULL on failure
 */
static struct pci_bus *xilinx_pcie_scan_bus(int nr, struct pci_sys_data *sys)
{
        struct xilinx_pcie_port *port = sys_to_pcie(sys);
        struct pci_bus *bus;

        port->root_busno = sys->busnr;
        bus = pci_scan_root_bus(port->dev, sys->busnr, &xilinx_pcie_ops,
                                sys, &sys->resources);

        return bus;
}

/**
 * xilinx_pcie_parse_and_add_res - Add resources by parsing ranges
 * @port: PCIe port information
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_pcie_parse_and_add_res(struct xilinx_pcie_port *port)
{
        struct device *dev = port->dev;
        struct device_node *node = dev->of_node;
        struct resource *mem;
        resource_size_t offset;
        struct of_pci_range_parser parser;
        struct of_pci_range range;
        struct pci_host_bridge_window *win;
        int err = 0, mem_resno = 0;

        /* Get the ranges */
        if (of_pci_range_parser_init(&parser, node)) {
                dev_err(dev, "missing \"ranges\" property\n");
                return -EINVAL;
        }

        /* Parse the ranges and add the resources found to the list */
        for_each_of_pci_range(&parser, &range) {

                if (mem_resno >= XILINX_MAX_NUM_RESOURCES) {
                        dev_err(dev, "Maximum memory resources exceeded\n");
                        return -EINVAL;
                }

                mem = devm_kmalloc(dev, sizeof(*mem), GFP_KERNEL);
                if (!mem) {
                        err = -ENOMEM;
                        goto free_resources;
                }

                of_pci_range_to_resource(&range, node, mem);

                switch (mem->flags & IORESOURCE_TYPE_BITS) {
                case IORESOURCE_MEM:
                        offset = range.cpu_addr - range.pci_addr;
                        mem_resno++;
                        break;
                default:
                        err = -EINVAL;
                        break;
                }

                if (err < 0) {
                        dev_warn(dev, "Invalid resource found %pR\n", mem);
                        continue;
                }

                err = request_resource(&iomem_resource, mem);
                if (err)
                        goto free_resources;

                pci_add_resource_offset(&port->resources, mem, offset);
        }

        /* Get the bus range */
        if (of_pci_parse_bus_range(node, &port->bus_range)) {
                u32 val = pcie_read(port, XILINX_PCIE_REG_BIR);
                u8 last;

                last = (val & XILINX_PCIE_BIR_ECAM_SZ_MASK) >>
                        XILINX_PCIE_BIR_ECAM_SZ_SHIFT;

                port->bus_range = (struct resource) {
                        .name   = node->name,
                        .start  = 0,
                        .end    = last,
                        .flags  = IORESOURCE_BUS,
                };
        }

        /* Register bus resource */
        pci_add_resource(&port->resources, &port->bus_range);

        return 0;

free_resources:
        release_child_resources(&iomem_resource);
        list_for_each_entry(win, &port->resources, list)
                devm_kfree(dev, win->res);
        pci_free_resource_list(&port->resources);

        return err;
}

/**
 * xilinx_pcie_parse_dt - Parse Device tree
 * @port: PCIe port information
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_pcie_parse_dt(struct xilinx_pcie_port *port)
{
        struct device *dev = port->dev;
        struct device_node *node = dev->of_node;
        struct resource regs;
        const char *type;
        int err;

        type = of_get_property(node, "device_type", NULL);
        if (!type || strcmp(type, "pci")) {
                dev_err(dev, "invalid \"device_type\" %s\n", type);
                return -EINVAL;
        }

        err = of_address_to_resource(node, 0, &regs);
        if (err) {
                dev_err(dev, "missing \"reg\" property\n");
                return err;
        }

        port->reg_base = devm_ioremap_resource(dev, &regs);
        if (IS_ERR(port->reg_base))
                return PTR_ERR(port->reg_base);

        port->irq = irq_of_parse_and_map(node, 0);
        err = devm_request_irq(dev, port->irq, xilinx_pcie_intr_handler,
                               IRQF_SHARED, "xilinx-pcie", port);
        if (err) {
                dev_err(dev, "unable to request irq %d\n", port->irq);
                return err;
        }

        return 0;
}

/**
 * xilinx_pcie_probe - Probe function
 * @pdev: Platform device pointer
 *
 * Return: '0' on success and error value on failure
 */
static int xilinx_pcie_probe(struct platform_device *pdev)
{
        struct xilinx_pcie_port *port;
        struct hw_pci hw;
        struct device *dev = &pdev->dev;
        int err;

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

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

        port->dev = dev;

        err = xilinx_pcie_parse_dt(port);
        if (err) {
                dev_err(dev, "Parsing DT failed\n");
                return err;
        }

        xilinx_pcie_init_port(port);

        err = xilinx_pcie_init_irq_domain(port);
        if (err) {
                dev_err(dev, "Failed creating IRQ Domain\n");
                return err;
        }

        /*
         * Parse PCI ranges, configuration bus range and
         * request their resources
         */
        INIT_LIST_HEAD(&port->resources);
        err = xilinx_pcie_parse_and_add_res(port);
        if (err) {
                dev_err(dev, "Failed adding resources\n");
                return err;
        }

        platform_set_drvdata(pdev, port);

        /* Register the device */
        memset(&hw, 0, sizeof(hw));
        hw = (struct hw_pci) {
                .nr_controllers = 1,
                .private_data   = (void **)&port,
                .setup          = xilinx_pcie_setup,
                .map_irq        = of_irq_parse_and_map_pci,
                .add_bus        = xilinx_pcie_add_bus,
                .scan           = xilinx_pcie_scan_bus,
                .ops            = &xilinx_pcie_ops,
        };
        pci_common_init_dev(dev, &hw);

        return 0;
}

/**
 * xilinx_pcie_remove - Remove function
 * @pdev: Platform device pointer
 *
 * Return: '0' always
 */
static int xilinx_pcie_remove(struct platform_device *pdev)
{
        struct xilinx_pcie_port *port = platform_get_drvdata(pdev);

        xilinx_pcie_free_irq_domain(port);

        return 0;
}

static struct of_device_id xilinx_pcie_of_match[] = {
        { .compatible = "xlnx,axi-pcie-host-1.00.a", },
        {}
};

static struct platform_driver xilinx_pcie_driver = {
        .driver = {
                .name = "xilinx-pcie",
                .owner = THIS_MODULE,
                .of_match_table = xilinx_pcie_of_match,
                .suppress_bind_attrs = true,
        },
        .probe = xilinx_pcie_probe,
        .remove = xilinx_pcie_remove,
};
module_platform_driver(xilinx_pcie_driver);

MODULE_AUTHOR("Xilinx Inc");
MODULE_DESCRIPTION("Xilinx AXI PCIe driver");
MODULE_LICENSE("GPL v2");