root/arch/loongarch/pci/acpi.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */
#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/pci-acpi.h>
#include <linux/pci-ecam.h>

#include <asm/pci.h>
#include <asm/numa.h>
#include <asm/loongson.h>

struct pci_root_info {
        struct acpi_pci_root_info common;
        struct pci_config_window *cfg;
};

void pcibios_add_bus(struct pci_bus *bus)
{
        acpi_pci_add_bus(bus);
}

int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
{
        struct acpi_device *adev = NULL;
        struct device *bus_dev = &bridge->bus->dev;
        struct pci_config_window *cfg = bridge->bus->sysdata;

        if (!acpi_disabled)
                adev = to_acpi_device(cfg->parent);

        ACPI_COMPANION_SET(&bridge->dev, adev);
        set_dev_node(bus_dev, pa_to_nid(cfg->res.start));

        return 0;
}

int acpi_pci_bus_find_domain_nr(struct pci_bus *bus)
{
        struct pci_config_window *cfg = bus->sysdata;
        struct acpi_device *adev = to_acpi_device(cfg->parent);
        struct acpi_pci_root *root = acpi_driver_data(adev);

        return root->segment;
}

static void acpi_release_root_info(struct acpi_pci_root_info *ci)
{
        struct pci_root_info *info;

        info = container_of(ci, struct pci_root_info, common);
        pci_ecam_free(info->cfg);
        kfree(ci->ops);
        kfree(info);
}

static int acpi_prepare_root_resources(struct acpi_pci_root_info *ci)
{
        int status;
        struct resource_entry *entry, *tmp;
        struct acpi_device *device = ci->bridge;

        status = acpi_pci_probe_root_resources(ci);
        if (status > 0) {
                resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
                        if (entry->res->flags & IORESOURCE_MEM) {
                                entry->offset = ci->root->mcfg_addr & GENMASK_ULL(63, 40);
                                entry->res->start |= entry->offset;
                                entry->res->end   |= entry->offset;
                        }
                }
                return status;
        }

        resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
                dev_dbg(&device->dev,
                           "host bridge window %pR (ignored)\n", entry->res);
                resource_list_destroy_entry(entry);
        }

        return 0;
}

/*
 * Create a PCI config space window
 *  - reserve mem region
 *  - alloc struct pci_config_window with space for all mappings
 *  - ioremap the config space
 */
static struct pci_config_window *arch_pci_ecam_create(struct device *dev,
                struct resource *cfgres, struct resource *busr, const struct pci_ecam_ops *ops)
{
        int bsz, bus_range, err;
        struct resource *conflict;
        struct pci_config_window *cfg;

        if (busr->start > busr->end)
                return ERR_PTR(-EINVAL);

        cfg = kzalloc_obj(*cfg);
        if (!cfg)
                return ERR_PTR(-ENOMEM);

        cfg->parent = dev;
        cfg->ops = ops;
        cfg->busr.start = busr->start;
        cfg->busr.end = busr->end;
        cfg->busr.flags = IORESOURCE_BUS;
        bus_range = resource_size(cfgres) >> ops->bus_shift;

        bsz = 1 << ops->bus_shift;

        cfg->res.start = cfgres->start;
        cfg->res.end = cfgres->end;
        cfg->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        cfg->res.name = "PCI ECAM";

        conflict = request_resource_conflict(&iomem_resource, &cfg->res);
        if (conflict) {
                err = -EBUSY;
                dev_err(dev, "can't claim ECAM area %pR: address conflict with %s %pR\n",
                        &cfg->res, conflict->name, conflict);
                goto err_exit;
        }

        cfg->win = pci_remap_cfgspace(cfgres->start, bus_range * bsz);
        if (!cfg->win)
                goto err_exit_iomap;

        if (ops->init) {
                err = ops->init(cfg);
                if (err)
                        goto err_exit;
        }
        dev_info(dev, "ECAM at %pR for %pR\n", &cfg->res, &cfg->busr);

        return cfg;

err_exit_iomap:
        err = -ENOMEM;
        dev_err(dev, "ECAM ioremap failed\n");
err_exit:
        pci_ecam_free(cfg);
        return ERR_PTR(err);
}

/*
 * Lookup the bus range for the domain in MCFG, and set up config space
 * mapping.
 */
static struct pci_config_window *
pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)
{
        int ret, bus_shift;
        u16 seg = root->segment;
        struct device *dev = &root->device->dev;
        struct resource cfgres;
        struct resource *bus_res = &root->secondary;
        struct pci_config_window *cfg;
        const struct pci_ecam_ops *ecam_ops;

        ret = pci_mcfg_lookup(root, &cfgres, &ecam_ops);
        if (ret < 0) {
                dev_err(dev, "%04x:%pR ECAM region not found, use default value\n", seg, bus_res);
                ecam_ops = &loongson_pci_ecam_ops;
                root->mcfg_addr = mcfg_addr_init(0);
        }

        bus_shift = ecam_ops->bus_shift ? : 20;

        if (bus_shift == 20)
                cfg = pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
        else {
                cfgres.start = root->mcfg_addr + (bus_res->start << bus_shift);
                cfgres.end = cfgres.start + (resource_size(bus_res) << bus_shift) - 1;
                cfgres.end |= BIT(28) + (((PCI_CFG_SPACE_EXP_SIZE - 1) & 0xf00) << 16);
                cfgres.flags = IORESOURCE_MEM;
                cfg = arch_pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
        }

        if (IS_ERR(cfg)) {
                dev_err(dev, "%04x:%pR error %ld mapping ECAM\n", seg, bus_res, PTR_ERR(cfg));
                return NULL;
        }

        return cfg;
}

struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
{
        struct pci_bus *bus;
        struct pci_root_info *info;
        struct pci_host_bridge *host;
        struct acpi_pci_root_ops *root_ops;
        int domain = root->segment;
        int busnum = root->secondary.start;

        info = kzalloc_obj(*info);
        if (!info) {
                pr_warn("pci_bus %04x:%02x: ignored (out of memory)\n", domain, busnum);
                return NULL;
        }

        root_ops = kzalloc_obj(*root_ops);
        if (!root_ops) {
                kfree(info);
                return NULL;
        }

        info->cfg = pci_acpi_setup_ecam_mapping(root);
        if (!info->cfg) {
                kfree(info);
                kfree(root_ops);
                return NULL;
        }

        root_ops->release_info = acpi_release_root_info;
        root_ops->prepare_resources = acpi_prepare_root_resources;
        root_ops->pci_ops = (struct pci_ops *)&info->cfg->ops->pci_ops;

        bus = pci_find_bus(domain, busnum);
        if (bus) {
                memcpy(bus->sysdata, info->cfg, sizeof(struct pci_config_window));
                kfree(info);
                kfree(root_ops);
        } else {
                struct pci_bus *child;

                bus = acpi_pci_root_create(root, root_ops,
                                           &info->common, info->cfg);
                if (!bus) {
                        kfree(info);
                        kfree(root_ops);
                        return NULL;
                }

                /* If we must preserve the resource configuration, claim now */
                host = pci_find_host_bridge(bus);
                if (host->preserve_config)
                        pci_bus_claim_resources(bus);

                /*
                 * Assign whatever was left unassigned. If we didn't claim above,
                 * this will reassign everything.
                 */
                pci_assign_unassigned_root_bus_resources(bus);

                list_for_each_entry(child, &bus->children, node)
                        pcie_bus_configure_settings(child);
        }

        return bus;
}