// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013-2015 ARM Limited, All Rights Reserved.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */

#include <linux/acpi_iort.h>
#include <linux/pci.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_pci.h>

static void its_mask_msi_irq(struct irq_data *d)
{
        pci_msi_mask_irq(d);
        irq_chip_mask_parent(d);
}

static void its_unmask_msi_irq(struct irq_data *d)
{
        pci_msi_unmask_irq(d);
        irq_chip_unmask_parent(d);
}

static struct irq_chip its_msi_irq_chip = {
        .name                   = "ITS-MSI",
        .irq_unmask             = its_unmask_msi_irq,
        .irq_mask               = its_mask_msi_irq,
        .irq_eoi                = irq_chip_eoi_parent,
};

static int its_pci_msi_vec_count(struct pci_dev *pdev, void *data)
{
        int msi, msix, *count = data;

        msi = max(pci_msi_vec_count(pdev), 0);
        msix = max(pci_msix_vec_count(pdev), 0);
        *count += max(msi, msix);

        return 0;
}

static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
{
        struct pci_dev **alias_dev = data;

        *alias_dev = pdev;

        return 0;
}

static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
                               int nvec, msi_alloc_info_t *info)
{
        struct pci_dev *pdev, *alias_dev;
        struct msi_domain_info *msi_info;
        int alias_count = 0, minnvec = 1;

        if (!dev_is_pci(dev))
                return -EINVAL;

        msi_info = msi_get_domain_info(domain->parent);

        pdev = to_pci_dev(dev);
        /*
         * If pdev is downstream of any aliasing bridges, take an upper
         * bound of how many other vectors could map to the same DevID.
         * Also tell the ITS that the signalling will come from a proxy
         * device, and that special allocation rules apply.
         */
        pci_for_each_dma_alias(pdev, its_get_pci_alias, &alias_dev);
        if (alias_dev != pdev) {
                if (alias_dev->subordinate)
                        pci_walk_bus(alias_dev->subordinate,
                                     its_pci_msi_vec_count, &alias_count);
                info->flags |= MSI_ALLOC_FLAGS_PROXY_DEVICE;
        }

        /* ITS specific DeviceID, as the core ITS ignores dev. */
        info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev);

        /*
         * Always allocate a power of 2, and special case device 0 for
         * broken systems where the DevID is not wired (and all devices
         * appear as DevID 0). For that reason, we generously allocate a
         * minimum of 32 MSIs for DevID 0. If you want more because all
         * your devices are aliasing to DevID 0, consider fixing your HW.
         */
        nvec = max(nvec, alias_count);
        if (!info->scratchpad[0].ul)
                minnvec = 32;
        nvec = max_t(int, minnvec, roundup_pow_of_two(nvec));
        return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info);
}

static struct msi_domain_ops its_pci_msi_ops = {
        .msi_prepare    = its_pci_msi_prepare,
};

static struct msi_domain_info its_pci_msi_domain_info = {
        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
                   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
        .ops    = &its_pci_msi_ops,
        .chip   = &its_msi_irq_chip,
};

static struct of_device_id its_device_id[] = {
        {       .compatible     = "arm,gic-v3-its",     },
        {},
};

static int __init its_pci_msi_init_one(struct fwnode_handle *handle,
                                       const char *name)
{
        struct irq_domain *parent;

        parent = irq_find_matching_fwnode(handle, DOMAIN_BUS_NEXUS);
        if (!parent || !msi_get_domain_info(parent)) {
                pr_err("%s: Unable to locate ITS domain\n", name);
                return -ENXIO;
        }

        if (!pci_msi_create_irq_domain(handle, &its_pci_msi_domain_info,
                                       parent)) {
                pr_err("%s: Unable to create PCI domain\n", name);
                return -ENOMEM;
        }

        return 0;
}

static int __init its_pci_of_msi_init(void)
{
        struct device_node *np;

        for (np = of_find_matching_node(NULL, its_device_id); np;
             np = of_find_matching_node(np, its_device_id)) {
                if (!of_device_is_available(np))
                        continue;
                if (!of_property_read_bool(np, "msi-controller"))
                        continue;

                if (its_pci_msi_init_one(of_node_to_fwnode(np), np->full_name))
                        continue;

                pr_info("PCI/MSI: %pOF domain created\n", np);
        }

        return 0;
}

#ifdef CONFIG_ACPI

static int __init
its_pci_msi_parse_madt(union acpi_subtable_headers *header,
                       const unsigned long end)
{
        struct acpi_madt_generic_translator *its_entry;
        struct fwnode_handle *dom_handle;
        const char *node_name;
        int err = -ENXIO;

        its_entry = (struct acpi_madt_generic_translator *)header;
        node_name = kasprintf(GFP_KERNEL, "ITS@0x%lx",
                              (long)its_entry->base_address);
        dom_handle = iort_find_domain_token(its_entry->translation_id);
        if (!dom_handle) {
                pr_err("%s: Unable to locate ITS domain handle\n", node_name);
                goto out;
        }

        err = its_pci_msi_init_one(dom_handle, node_name);
        if (!err)
                pr_info("PCI/MSI: %s domain created\n", node_name);

out:
        kfree(node_name);
        return err;
}

static int __init its_pci_acpi_msi_init(void)
{
        acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
                              its_pci_msi_parse_madt, 0);
        return 0;
}
#else
static int __init its_pci_acpi_msi_init(void)
{
        return 0;
}
#endif

static int __init its_pci_msi_init(void)
{
        its_pci_of_msi_init();
        its_pci_acpi_msi_init();

        return 0;
}
early_initcall(its_pci_msi_init);