// SPDX-License-Identifier: GPL-2.0
/*
 * PCIe host controller driver for Mobiveil PCIe Host controller
 *
 * Copyright (c) 2018 Mobiveil Inc.
 * Copyright 2019-2020 NXP
 *
 * Author: Subrahmanya Lingappa <l.subrahmanya@mobiveil.co.in>
 *         Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip/chained_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_irq.h>
#include <linux/of_platform.h>
#include <linux/of_pci.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "pcie-mobiveil.h"

static bool mobiveil_pcie_valid_device(struct pci_bus *bus, unsigned int devfn)
{
        /* Only one device down on each root port */
        if (pci_is_root_bus(bus) && (devfn > 0))
                return false;

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

        return true;
}

/*
 * mobiveil_pcie_map_bus - routine to get the configuration base of either
 * root port or endpoint
 */
static void __iomem *mobiveil_pcie_map_bus(struct pci_bus *bus,
                                           unsigned int devfn, int where)
{
        struct mobiveil_pcie *pcie = bus->sysdata;
        struct mobiveil_root_port *rp = &pcie->rp;
        u32 value;

        if (!mobiveil_pcie_valid_device(bus, devfn))
                return NULL;

        /* RC config access */
        if (pci_is_root_bus(bus))
                return pcie->csr_axi_slave_base + where;

        /*
         * EP config access (in Config/APIO space)
         * Program PEX Address base (31..16 bits) with appropriate value
         * (BDF) in PAB_AXI_AMAP_PEX_WIN_L0 Register.
         * Relies on pci_lock serialization
         */
        value = bus->number << PAB_BUS_SHIFT |
                PCI_SLOT(devfn) << PAB_DEVICE_SHIFT |
                PCI_FUNC(devfn) << PAB_FUNCTION_SHIFT;

        mobiveil_csr_writel(pcie, value, PAB_AXI_AMAP_PEX_WIN_L(WIN_NUM_0));

        return rp->config_axi_slave_base + where;
}

static struct pci_ops mobiveil_pcie_ops = {
        .map_bus = mobiveil_pcie_map_bus,
        .read = pci_generic_config_read,
        .write = pci_generic_config_write,
};

static void mobiveil_pcie_isr(struct irq_desc *desc)
{
        struct irq_chip *chip = irq_desc_get_chip(desc);
        struct mobiveil_pcie *pcie = irq_desc_get_handler_data(desc);
        struct device *dev = &pcie->pdev->dev;
        struct mobiveil_root_port *rp = &pcie->rp;
        struct mobiveil_msi *msi = &rp->msi;
        u32 msi_data, msi_addr_lo, msi_addr_hi;
        u32 intr_status, msi_status;
        unsigned long shifted_status;
        u32 bit, virq, val, mask;

        /*
         * The core provides a single interrupt for both INTx/MSI messages.
         * So we'll read both INTx and MSI status
         */

        chained_irq_enter(chip, desc);

        /* read INTx status */
        val = mobiveil_csr_readl(pcie, PAB_INTP_AMBA_MISC_STAT);
        mask = mobiveil_csr_readl(pcie, PAB_INTP_AMBA_MISC_ENB);
        intr_status = val & mask;

        /* Handle INTx */
        if (intr_status & PAB_INTP_INTX_MASK) {
                shifted_status = mobiveil_csr_readl(pcie,
                                                    PAB_INTP_AMBA_MISC_STAT);
                shifted_status &= PAB_INTP_INTX_MASK;
                shifted_status >>= PAB_INTX_START;
                do {
                        for_each_set_bit(bit, &shifted_status, PCI_NUM_INTX) {
                                virq = irq_find_mapping(rp->intx_domain,
                                                        bit + 1);
                                if (virq)
                                        generic_handle_irq(virq);
                                else
                                        dev_err_ratelimited(dev, "unexpected IRQ, INT%d\n",
                                                            bit);

                                /* clear interrupt handled */
                                mobiveil_csr_writel(pcie,
                                                    1 << (PAB_INTX_START + bit),
                                                    PAB_INTP_AMBA_MISC_STAT);
                        }

                        shifted_status = mobiveil_csr_readl(pcie,
                                                            PAB_INTP_AMBA_MISC_STAT);
                        shifted_status &= PAB_INTP_INTX_MASK;
                        shifted_status >>= PAB_INTX_START;
                } while (shifted_status != 0);
        }

        /* read extra MSI status register */
        msi_status = readl_relaxed(pcie->apb_csr_base + MSI_STATUS_OFFSET);

        /* handle MSI interrupts */
        while (msi_status & 1) {
                msi_data = readl_relaxed(pcie->apb_csr_base + MSI_DATA_OFFSET);

                /*
                 * MSI_STATUS_OFFSET register gets updated to zero
                 * once we pop not only the MSI data but also address
                 * from MSI hardware FIFO. So keeping these following
                 * two dummy reads.
                 */
                msi_addr_lo = readl_relaxed(pcie->apb_csr_base +
                                            MSI_ADDR_L_OFFSET);
                msi_addr_hi = readl_relaxed(pcie->apb_csr_base +
                                            MSI_ADDR_H_OFFSET);
                dev_dbg(dev, "MSI registers, data: %08x, addr: %08x:%08x\n",
                        msi_data, msi_addr_hi, msi_addr_lo);

                virq = irq_find_mapping(msi->dev_domain, msi_data);
                if (virq)
                        generic_handle_irq(virq);

                msi_status = readl_relaxed(pcie->apb_csr_base +
                                           MSI_STATUS_OFFSET);
        }

        /* Clear the interrupt status */
        mobiveil_csr_writel(pcie, intr_status, PAB_INTP_AMBA_MISC_STAT);
        chained_irq_exit(chip, desc);
}

static int mobiveil_pcie_parse_dt(struct mobiveil_pcie *pcie)
{
        struct device *dev = &pcie->pdev->dev;
        struct platform_device *pdev = pcie->pdev;
        struct device_node *node = dev->of_node;
        struct mobiveil_root_port *rp = &pcie->rp;
        struct resource *res;

        /* map config resource */
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                           "config_axi_slave");
        rp->config_axi_slave_base = devm_pci_remap_cfg_resource(dev, res);
        if (IS_ERR(rp->config_axi_slave_base))
                return PTR_ERR(rp->config_axi_slave_base);
        rp->ob_io_res = res;

        /* map csr resource */
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                           "csr_axi_slave");
        pcie->csr_axi_slave_base = devm_pci_remap_cfg_resource(dev, res);
        if (IS_ERR(pcie->csr_axi_slave_base))
                return PTR_ERR(pcie->csr_axi_slave_base);
        pcie->pcie_reg_base = res->start;

        /* read the number of windows requested */
        if (of_property_read_u32(node, "apio-wins", &pcie->apio_wins))
                pcie->apio_wins = MAX_PIO_WINDOWS;

        if (of_property_read_u32(node, "ppio-wins", &pcie->ppio_wins))
                pcie->ppio_wins = MAX_PIO_WINDOWS;

        return 0;
}

static void mobiveil_pcie_enable_msi(struct mobiveil_pcie *pcie)
{
        phys_addr_t msg_addr = pcie->pcie_reg_base;
        struct mobiveil_msi *msi = &pcie->rp.msi;

        msi->num_of_vectors = PCI_NUM_MSI;
        msi->msi_pages_phys = (phys_addr_t)msg_addr;

        writel_relaxed(lower_32_bits(msg_addr),
                       pcie->apb_csr_base + MSI_BASE_LO_OFFSET);
        writel_relaxed(upper_32_bits(msg_addr),
                       pcie->apb_csr_base + MSI_BASE_HI_OFFSET);
        writel_relaxed(4096, pcie->apb_csr_base + MSI_SIZE_OFFSET);
        writel_relaxed(1, pcie->apb_csr_base + MSI_ENABLE_OFFSET);
}

int mobiveil_host_init(struct mobiveil_pcie *pcie, bool reinit)
{
        struct mobiveil_root_port *rp = &pcie->rp;
        struct pci_host_bridge *bridge = rp->bridge;
        u32 value, pab_ctrl, type;
        struct resource_entry *win;

        pcie->ib_wins_configured = 0;
        pcie->ob_wins_configured = 0;

        if (!reinit) {
                /* setup bus numbers */
                value = mobiveil_csr_readl(pcie, PCI_PRIMARY_BUS);
                value &= 0xff000000;
                value |= 0x00ff0100;
                mobiveil_csr_writel(pcie, value, PCI_PRIMARY_BUS);
        }

        /*
         * program Bus Master Enable Bit in Command Register in PAB Config
         * Space
         */
        value = mobiveil_csr_readl(pcie, PCI_COMMAND);
        value |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER;
        mobiveil_csr_writel(pcie, value, PCI_COMMAND);

        /*
         * program PIO Enable Bit to 1 (and PEX PIO Enable to 1) in PAB_CTRL
         * register
         */
        pab_ctrl = mobiveil_csr_readl(pcie, PAB_CTRL);
        pab_ctrl |= (1 << AMBA_PIO_ENABLE_SHIFT) | (1 << PEX_PIO_ENABLE_SHIFT);
        mobiveil_csr_writel(pcie, pab_ctrl, PAB_CTRL);

        /*
         * program PIO Enable Bit to 1 and Config Window Enable Bit to 1 in
         * PAB_AXI_PIO_CTRL Register
         */
        value = mobiveil_csr_readl(pcie, PAB_AXI_PIO_CTRL);
        value |= APIO_EN_MASK;
        mobiveil_csr_writel(pcie, value, PAB_AXI_PIO_CTRL);

        /* Enable PCIe PIO master */
        value = mobiveil_csr_readl(pcie, PAB_PEX_PIO_CTRL);
        value |= 1 << PIO_ENABLE_SHIFT;
        mobiveil_csr_writel(pcie, value, PAB_PEX_PIO_CTRL);

        /*
         * we'll program one outbound window for config reads and
         * another default inbound window for all the upstream traffic
         * rest of the outbound windows will be configured according to
         * the "ranges" field defined in device tree
         */

        /* config outbound translation window */
        program_ob_windows(pcie, WIN_NUM_0, rp->ob_io_res->start, 0,
                           CFG_WINDOW_TYPE, resource_size(rp->ob_io_res));

        /* memory inbound translation window */
        program_ib_windows(pcie, WIN_NUM_0, 0, 0, MEM_WINDOW_TYPE, IB_WIN_SIZE);

        /* Get the I/O and memory ranges from DT */
        resource_list_for_each_entry(win, &bridge->windows) {
                if (resource_type(win->res) == IORESOURCE_MEM)
                        type = MEM_WINDOW_TYPE;
                else if (resource_type(win->res) == IORESOURCE_IO)
                        type = IO_WINDOW_TYPE;
                else
                        continue;

                /* configure outbound translation window */
                program_ob_windows(pcie, pcie->ob_wins_configured,
                                   win->res->start,
                                   win->res->start - win->offset,
                                   type, resource_size(win->res));
        }

        /* fixup for PCIe class register */
        value = mobiveil_csr_readl(pcie, PAB_INTP_AXI_PIO_CLASS);
        value &= 0xff;
        value |= (PCI_CLASS_BRIDGE_PCI << 16);
        mobiveil_csr_writel(pcie, value, PAB_INTP_AXI_PIO_CLASS);

        return 0;
}

static void mobiveil_mask_intx_irq(struct irq_data *data)
{
        struct irq_desc *desc = irq_to_desc(data->irq);
        struct mobiveil_pcie *pcie;
        struct mobiveil_root_port *rp;
        unsigned long flags;
        u32 mask, shifted_val;

        pcie = irq_desc_get_chip_data(desc);
        rp = &pcie->rp;
        mask = 1 << ((data->hwirq + PAB_INTX_START) - 1);
        raw_spin_lock_irqsave(&rp->intx_mask_lock, flags);
        shifted_val = mobiveil_csr_readl(pcie, PAB_INTP_AMBA_MISC_ENB);
        shifted_val &= ~mask;
        mobiveil_csr_writel(pcie, shifted_val, PAB_INTP_AMBA_MISC_ENB);
        raw_spin_unlock_irqrestore(&rp->intx_mask_lock, flags);
}

static void mobiveil_unmask_intx_irq(struct irq_data *data)
{
        struct irq_desc *desc = irq_to_desc(data->irq);
        struct mobiveil_pcie *pcie;
        struct mobiveil_root_port *rp;
        unsigned long flags;
        u32 shifted_val, mask;

        pcie = irq_desc_get_chip_data(desc);
        rp = &pcie->rp;
        mask = 1 << ((data->hwirq + PAB_INTX_START) - 1);
        raw_spin_lock_irqsave(&rp->intx_mask_lock, flags);
        shifted_val = mobiveil_csr_readl(pcie, PAB_INTP_AMBA_MISC_ENB);
        shifted_val |= mask;
        mobiveil_csr_writel(pcie, shifted_val, PAB_INTP_AMBA_MISC_ENB);
        raw_spin_unlock_irqrestore(&rp->intx_mask_lock, flags);
}

static struct irq_chip intx_irq_chip = {
        .name = "mobiveil_pcie:intx",
        .irq_enable = mobiveil_unmask_intx_irq,
        .irq_disable = mobiveil_mask_intx_irq,
        .irq_mask = mobiveil_mask_intx_irq,
        .irq_unmask = mobiveil_unmask_intx_irq,
};

/* routine to setup the INTx related data */
static int mobiveil_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
                                  irq_hw_number_t hwirq)
{
        irq_set_chip_and_handler(irq, &intx_irq_chip, handle_level_irq);
        irq_set_chip_data(irq, domain->host_data);

        return 0;
}

/* INTx domain operations structure */
static const struct irq_domain_ops intx_domain_ops = {
        .map = mobiveil_pcie_intx_map,
};

static struct irq_chip mobiveil_msi_irq_chip = {
        .name = "Mobiveil PCIe MSI",
        .irq_mask = pci_msi_mask_irq,
        .irq_unmask = pci_msi_unmask_irq,
};

static struct msi_domain_info mobiveil_msi_domain_info = {
        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
                   MSI_FLAG_PCI_MSIX),
        .chip   = &mobiveil_msi_irq_chip,
};

static void mobiveil_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
        struct mobiveil_pcie *pcie = irq_data_get_irq_chip_data(data);
        phys_addr_t addr = pcie->pcie_reg_base + (data->hwirq * sizeof(int));

        msg->address_lo = lower_32_bits(addr);
        msg->address_hi = upper_32_bits(addr);
        msg->data = data->hwirq;

        dev_dbg(&pcie->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
                (int)data->hwirq, msg->address_hi, msg->address_lo);
}

static int mobiveil_msi_set_affinity(struct irq_data *irq_data,
                                     const struct cpumask *mask, bool force)
{
        return -EINVAL;
}

static struct irq_chip mobiveil_msi_bottom_irq_chip = {
        .name                   = "Mobiveil MSI",
        .irq_compose_msi_msg    = mobiveil_compose_msi_msg,
        .irq_set_affinity       = mobiveil_msi_set_affinity,
};

static int mobiveil_irq_msi_domain_alloc(struct irq_domain *domain,
                                         unsigned int virq,
                                         unsigned int nr_irqs, void *args)
{
        struct mobiveil_pcie *pcie = domain->host_data;
        struct mobiveil_msi *msi = &pcie->rp.msi;
        unsigned long bit;

        WARN_ON(nr_irqs != 1);
        mutex_lock(&msi->lock);

        bit = find_first_zero_bit(msi->msi_irq_in_use, msi->num_of_vectors);
        if (bit >= msi->num_of_vectors) {
                mutex_unlock(&msi->lock);
                return -ENOSPC;
        }

        set_bit(bit, msi->msi_irq_in_use);

        mutex_unlock(&msi->lock);

        irq_domain_set_info(domain, virq, bit, &mobiveil_msi_bottom_irq_chip,
                            domain->host_data, handle_level_irq, NULL, NULL);
        return 0;
}

static void mobiveil_irq_msi_domain_free(struct irq_domain *domain,
                                         unsigned int virq,
                                         unsigned int nr_irqs)
{
        struct irq_data *d = irq_domain_get_irq_data(domain, virq);
        struct mobiveil_pcie *pcie = irq_data_get_irq_chip_data(d);
        struct mobiveil_msi *msi = &pcie->rp.msi;

        mutex_lock(&msi->lock);

        if (!test_bit(d->hwirq, msi->msi_irq_in_use))
                dev_err(&pcie->pdev->dev, "trying to free unused MSI#%lu\n",
                        d->hwirq);
        else
                __clear_bit(d->hwirq, msi->msi_irq_in_use);

        mutex_unlock(&msi->lock);
}
static const struct irq_domain_ops msi_domain_ops = {
        .alloc  = mobiveil_irq_msi_domain_alloc,
        .free   = mobiveil_irq_msi_domain_free,
};

static int mobiveil_allocate_msi_domains(struct mobiveil_pcie *pcie)
{
        struct device *dev = &pcie->pdev->dev;
        struct fwnode_handle *fwnode = of_node_to_fwnode(dev->of_node);
        struct mobiveil_msi *msi = &pcie->rp.msi;

        mutex_init(&msi->lock);
        msi->dev_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
                                                &msi_domain_ops, pcie);
        if (!msi->dev_domain) {
                dev_err(dev, "failed to create IRQ domain\n");
                return -ENOMEM;
        }

        msi->msi_domain = pci_msi_create_irq_domain(fwnode,
                                                    &mobiveil_msi_domain_info,
                                                    msi->dev_domain);
        if (!msi->msi_domain) {
                dev_err(dev, "failed to create MSI domain\n");
                irq_domain_remove(msi->dev_domain);
                return -ENOMEM;
        }

        return 0;
}

static int mobiveil_pcie_init_irq_domain(struct mobiveil_pcie *pcie)
{
        struct device *dev = &pcie->pdev->dev;
        struct device_node *node = dev->of_node;
        struct mobiveil_root_port *rp = &pcie->rp;

        /* setup INTx */
        rp->intx_domain = irq_domain_add_linear(node, PCI_NUM_INTX,
                                                &intx_domain_ops, pcie);

        if (!rp->intx_domain) {
                dev_err(dev, "Failed to get a INTx IRQ domain\n");
                return -ENOMEM;
        }

        raw_spin_lock_init(&rp->intx_mask_lock);

        /* setup MSI */
        return mobiveil_allocate_msi_domains(pcie);
}

static int mobiveil_pcie_integrated_interrupt_init(struct mobiveil_pcie *pcie)
{
        struct platform_device *pdev = pcie->pdev;
        struct device *dev = &pdev->dev;
        struct mobiveil_root_port *rp = &pcie->rp;
        struct resource *res;
        int ret;

        /* map MSI config resource */
        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "apb_csr");
        pcie->apb_csr_base = devm_pci_remap_cfg_resource(dev, res);
        if (IS_ERR(pcie->apb_csr_base))
                return PTR_ERR(pcie->apb_csr_base);

        /* setup MSI hardware registers */
        mobiveil_pcie_enable_msi(pcie);

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

        /* initialize the IRQ domains */
        ret = mobiveil_pcie_init_irq_domain(pcie);
        if (ret) {
                dev_err(dev, "Failed creating IRQ Domain\n");
                return ret;
        }

        irq_set_chained_handler_and_data(rp->irq, mobiveil_pcie_isr, pcie);

        /* Enable interrupts */
        mobiveil_csr_writel(pcie, (PAB_INTP_INTX_MASK | PAB_INTP_MSI_MASK),
                            PAB_INTP_AMBA_MISC_ENB);


        return 0;
}

static int mobiveil_pcie_interrupt_init(struct mobiveil_pcie *pcie)
{
        struct mobiveil_root_port *rp = &pcie->rp;

        if (rp->ops->interrupt_init)
                return rp->ops->interrupt_init(pcie);

        return mobiveil_pcie_integrated_interrupt_init(pcie);
}

static bool mobiveil_pcie_is_bridge(struct mobiveil_pcie *pcie)
{
        u32 header_type;

        header_type = mobiveil_csr_readb(pcie, PCI_HEADER_TYPE);
        header_type &= 0x7f;

        return header_type == PCI_HEADER_TYPE_BRIDGE;
}

int mobiveil_pcie_host_probe(struct mobiveil_pcie *pcie)
{
        struct mobiveil_root_port *rp = &pcie->rp;
        struct pci_host_bridge *bridge = rp->bridge;
        struct device *dev = &pcie->pdev->dev;
        int ret;

        ret = mobiveil_pcie_parse_dt(pcie);
        if (ret) {
                dev_err(dev, "Parsing DT failed, ret: %x\n", ret);
                return ret;
        }

        if (!mobiveil_pcie_is_bridge(pcie))
                return -ENODEV;

        /*
         * configure all inbound and outbound windows and prepare the RC for
         * config access
         */
        ret = mobiveil_host_init(pcie, false);
        if (ret) {
                dev_err(dev, "Failed to initialize host\n");
                return ret;
        }

        ret = mobiveil_pcie_interrupt_init(pcie);
        if (ret) {
                dev_err(dev, "Interrupt init failed\n");
                return ret;
        }

        /* Initialize bridge */
        bridge->sysdata = pcie;
        bridge->ops = &mobiveil_pcie_ops;

        ret = mobiveil_bringup_link(pcie);
        if (ret) {
                dev_info(dev, "link bring-up failed\n");
                return ret;
        }

        return pci_host_probe(bridge);
}