// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
#include <acpica/acpi.h>
#include <acpica/actypes.h>
#include <acpica/acuuid.h>
#include <bits/limits.h>
#include <ddk/debug.h>
#include <fbl/alloc_checker.h>
#include <fbl/unique_ptr.h>
#include <fbl/vector.h>
#include <inttypes.h>
#include <region-alloc/region-alloc.h>
#include <stdio.h>
#include <string.h>

#include "acpi-private.h"
#include "methods.h"
#include "pci.h"
#include "pciroot.h"
#include "resources.h"

// This file contains the implementation for the code supporting the in-progress userland
// pci bus driver.

static fbl::Vector<pci_mcfg_allocation_t*> mcfg_allocations;
const char* kLogTag = "acpi-pci:";

// These allocators container available regions of physical address space in the memory
// map that we should be able to allocate bars from. Different allocators exist for 32
// and 64 bit bars so that we can be sure addresses at < 4GB are preserved for 32 bit
// bars.
RegionAllocator kMmio32Alloc;
RegionAllocator kMmio64Alloc;
RegionAllocator kIoAlloc;

const RegionAllocator* Get32BitMmioAllocator() { return &kMmio32Alloc; }
const RegionAllocator* Get64BitMmioAllocator() { return &kMmio64Alloc; }
const RegionAllocator* GetIoAllocator() { return &kIoAlloc; }

struct report_current_resources_ctx {
    zx_handle_t pci_handle;
    bool device_is_root_bridge;
    bool add_pass;
};

static ACPI_STATUS report_current_resources_resource_cb_ex(ACPI_RESOURCE* res, void* _ctx) {
    auto* ctx = static_cast<struct report_current_resources_ctx*>(_ctx);
    zx_status_t status;

    bool is_mmio = false;
    uint64_t base = 0;
    uint64_t len = 0;
    bool add_range = false;

    if (resource_is_memory(res)) {
        resource_memory_t mem;
        status = resource_parse_memory(res, &mem);
        if (status != ZX_OK || mem.minimum != mem.maximum) {
            return AE_ERROR;
        }

        is_mmio = true;
        base = mem.minimum;
        len = mem.address_length;
    } else if (resource_is_address(res)) {
        resource_address_t addr;
        status = resource_parse_address(res, &addr);
        if (status != ZX_OK) {
            return AE_ERROR;
        }

        if (addr.resource_type == RESOURCE_ADDRESS_MEMORY) {
            is_mmio = true;
        } else if (addr.resource_type == RESOURCE_ADDRESS_IO) {
            is_mmio = false;
        } else {
            return AE_OK;
        }

        if (!addr.min_address_fixed || !addr.max_address_fixed || addr.maximum < addr.minimum) {
            printf("WARNING: ACPI found bad _CRS address entry\n");
            return AE_OK;
        }

        // We compute len from maximum rather than address_length, since some
        // implementations don't set address_length...
        base = addr.minimum;
        len = addr.maximum - base + 1;

        // PCI root bridges report downstream resources via _CRS.  Since we're
        // gathering data on acceptable ranges for PCI to use for MMIO, consider
        // non-consume-only address resources to be valid for PCI MMIO.
        if (ctx->device_is_root_bridge && !addr.consumed_only) {
            add_range = true;
        }
    } else if (resource_is_io(res)) {
        resource_io_t io;
        status = resource_parse_io(res, &io);
        if (status != ZX_OK) {
            return AE_ERROR;
        }

        if (io.minimum != io.maximum) {
            printf("WARNING: ACPI found bad _CRS IO entry\n");
            return AE_OK;
        }

        is_mmio = false;
        base = io.minimum;
        len = io.address_length;
    } else {
        return AE_OK;
    }

    // Ignore empty regions that are reported, and skip any resources that
    // aren't for the pass we're doing.
    if (len == 0 || add_range != ctx->add_pass) {
        return AE_OK;
    }

    if (add_range && is_mmio && base < 1024 * 1024) {
        // The PC platform defines many legacy regions below 1MB that we do not
        // want PCIe to try to map onto.
        zxlogf(INFO, "Skipping adding MMIO range, due to being below 1MB\n");
        return AE_OK;
    }

    // Add/Subtract the [base, len] region we found through ACPI to the allocators
    // that PCI can use to allocate BARs.
    RegionAllocator* alloc;
    if (is_mmio) {
        if (base + len < UINT32_MAX) {
            alloc = &kMmio32Alloc;
        } else {
            alloc = &kMmio64Alloc;
        }
    } else {
        alloc = &kIoAlloc;
    }

    zxlogf(TRACE, "ACPI range modification: %sing %s %016lx %016lx\n",
           add_range ? "add" : "subtract", is_mmio ? "MMIO" : "PIO", base, len);
    if (add_range) {
        status = alloc->AddRegion({.base = base, .size = len}, true);
    } else {
        status = alloc->SubtractRegion({.base = base, .size = len}, true);
    }

    if (status != ZX_OK) {
        if (add_range) {
            zxlogf(INFO, "Failed to add range: %d\n", status);
        } else {
            // If we are subtracting a range and fail, abort.  This is bad.
            return AE_ERROR;
        }
    }
    return AE_OK;
}

static ACPI_STATUS report_current_resources_device_cb_ex(
    ACPI_HANDLE object, uint32_t nesting_level, void* _ctx, void** ret) {

    ACPI_DEVICE_INFO* info = NULL;
    ACPI_STATUS status = AcpiGetObjectInfo(object, &info);
    if (status != AE_OK) {
        return status;
    }

    auto* ctx = static_cast<struct report_current_resources_ctx*>(_ctx);
    ctx->device_is_root_bridge = (info->Flags & ACPI_PCI_ROOT_BRIDGE) != 0;

    ACPI_FREE(info);

    status = AcpiWalkResources(object, (char*)"_CRS", report_current_resources_resource_cb_ex, ctx);
    if (status == AE_NOT_FOUND || status == AE_OK) {
        return AE_OK;
    }
    return status;
}

/* @brief Report current resources to the kernel PCI driver
 *
 * Walks the ACPI namespace and use the reported current resources to inform
   the kernel PCI interface about what memory it shouldn't use.
 *
 * @param root_resource_handle The handle to pass to the kernel when talking
 * to the PCI driver.
 *
 * @return ZX_OK on success
 */
zx_status_t pci_report_current_resources_ex(zx_handle_t root_resource_handle) {
    // First we search for resources to add, then we subtract out things that
    // are being consumed elsewhere.  This forces an ordering on the
    // operations so that it should be consistent, and should protect against
    // inconistencies in the _CRS methods.

    // Walk the device tree and add to the PCIe IO ranges any resources
    // "produced" by the PCI root in the ACPI namespace.
    struct report_current_resources_ctx ctx = {
        .pci_handle = root_resource_handle,
        .device_is_root_bridge = false,
        .add_pass = true,
    };
    ACPI_STATUS status = AcpiGetDevices(NULL, report_current_resources_device_cb_ex, &ctx, NULL);
    if (status != AE_OK) {
        return ZX_ERR_INTERNAL;
    }

    // Removes resources we believe are in use by other parts of the platform
    ctx = (struct report_current_resources_ctx){
        .pci_handle = root_resource_handle,
        .device_is_root_bridge = false,
        .add_pass = false,
    };
    status = AcpiGetDevices(NULL, report_current_resources_device_cb_ex, &ctx, NULL);
    if (status != AE_OK) {
        return ZX_ERR_INTERNAL;
    }

    return ZX_OK;
}

// Reads the MCFG table from ACPI and caches it for later calls
// to pci_ger_segment_mcfg_alloc()
static zx_status_t pci_read_mcfg_table(void) {
    // Systems will have an MCFG table unless they only support legacy PCI.
    ACPI_TABLE_HEADER* raw_table = NULL;
    ACPI_STATUS status = AcpiGetTable(const_cast<char*>(ACPI_SIG_MCFG), 1, &raw_table);
    if (status != AE_OK) {
        zxlogf(TRACE, "%s no MCFG table found.\n", kLogTag);
        return ZX_ERR_NOT_FOUND;
    }

    // The MCFG table contains a variable number of Extended Config tables
    // hanging off of the end.  Typically there will be one, but more
    // complicated systems may have multiple per PCI Host Bridge. The length in
    // the header is the overall size, so that is used to calculate how many
    // ECAMs are included.
    ACPI_TABLE_MCFG* mcfg = reinterpret_cast<ACPI_TABLE_MCFG*>(raw_table);
    uintptr_t table_start = reinterpret_cast<uintptr_t>(mcfg) + sizeof(ACPI_TABLE_MCFG);
    uintptr_t table_end = reinterpret_cast<uintptr_t>(mcfg) + mcfg->Header.Length;
    size_t table_bytes = table_end - table_start;
    if (table_bytes % sizeof(pci_mcfg_allocation_t)) {
        zxlogf(ERROR, "%s MCFG table has invalid size %zu\n", kLogTag, table_bytes);
        return ZX_ERR_INTERNAL;
    }

    // Each allocation corresponds to a particular PCI Segment Group. We'll
    // store them so that the protocol can return them for bus driver instances
    // later.
    for (unsigned i = 0; i < table_bytes / sizeof(pci_mcfg_allocation_t); i++) {
        auto entry = &(reinterpret_cast<pci_mcfg_allocation_t*>(table_start))[i];
        mcfg_allocations.push_back(entry);
        zxlogf(TRACE, "%s MCFG allocation %u (Addr = %#lx, Segment = %u, Start = %u, End = %u)\n",
               kLogTag, i, entry->base_address, entry->segment_group, entry->start_bus_num,
               entry->end_bus_num);
    }
    return ZX_OK;
}

bool pci_platform_has_mcfg(void) {
    return (mcfg_allocations.size() != 0);
}

// Search the MCFG allocations found earlier for an entry matching a given
// segment a host bridge is a part of. Per the PCI Firmware spec v3 table 4-3
// note 1, a given segment group will contain only a single mcfg allocation
// entry.
zx_status_t pci_get_segment_mcfg_alloc(unsigned segment_group, pci_mcfg_allocation_t* out) {
    for (auto& entry : mcfg_allocations) {
        if (entry->segment_group == segment_group) {
            *out = *entry;
            return ZX_OK;
        }
    }
    return ZX_ERR_NOT_FOUND;
}

zx_status_t pci_init_bookkeeping(void) {
    zx_status_t status;
    auto region_pool = RegionAllocator::RegionPool::Create(PAGE_SIZE);
    if (region_pool == nullptr) {
        return ZX_ERR_NO_MEMORY;
    }

    status = kMmio32Alloc.SetRegionPool(region_pool);
    if (status != ZX_OK) {
        return status;
    }

    status = kMmio64Alloc.SetRegionPool(region_pool);
    if (status != ZX_OK) {
        return status;
    }

    status = kIoAlloc.SetRegionPool(region_pool);
    if (status != ZX_OK) {
        return status;
    }

    // MCFG table will only exist with PCIe so 'not found' is not a failure case.
    status = pci_read_mcfg_table();
    if (status != ZX_OK && status != ZX_ERR_NOT_FOUND) {
        zxlogf(ERROR, "%s error attempting to read mcfg table %d\n", kLogTag, status);
        return status;
    }

    // Please do not use get_root_resource() in new code. See ZX-1467.
    status = pci_report_current_resources_ex(get_root_resource());
    if (status != ZX_OK) {
        zxlogf(ERROR, "%s error attempting to populate PCI allocators %d\n", kLogTag, status);
        return status;
    }

    return ZX_OK;
}

zx_status_t pci_init(zx_device_t* parent,
                     ACPI_HANDLE object,
                     ACPI_DEVICE_INFO* info,
                     publish_acpi_device_ctx_t* ctx) {
    static bool pci_bookkeeping_initialized = false;
    zx_status_t status = ZX_OK;

    // If it's the first time we've found a root we need to set up our address
    // space allocators and walk the various ACPI tables.
    if (!pci_bookkeeping_initialized) {
        status = pci_init_bookkeeping();
        if (status != ZX_OK) {
            return status;
        }
        pci_bookkeeping_initialized = true;
    }

    // Build up a context structure for the PCI Root / Host Bridge we've found.
    // If we find _BBN / _SEG we will use those, but if we don't we can fall
    // back on having an ecam from mcfg allocations.
    fbl::AllocChecker ac;
    auto dev_ctx = fbl::unique_ptr<pciroot_ctx_t>(new (&ac) pciroot_ctx_t());
    if (!ac.check()) {
        zxlogf(ERROR, "failed to allocate pciroot ctx: %d!\n", status);
        return ZX_ERR_NO_MEMORY;
    }

    dev_ctx->acpi_object = object;
    dev_ctx->acpi_device_info = *info;
    // ACPI names are stored as 4 bytes in a u32
    memcpy(dev_ctx->name, &info->Name, 4);

    status = acpi_bbn_call(object, &dev_ctx->info.start_bus_num);
    if (status != ZX_OK && status != ZX_ERR_NOT_FOUND) {
        zxlogf(TRACE, "%s Unable to read _BBN for '%s' (%d), assuming base bus of 0\n",
               kLogTag, dev_ctx->name, status);

        // Until we find an ecam we assume this potential legacy pci bus spans
        // bus 0 to bus 255 in its segment group.
        dev_ctx->info.end_bus_num = 255;
    }
    bool found_bbn = (status == ZX_OK);

    status = acpi_seg_call(object, &dev_ctx->info.segment_group);
    if (status != ZX_OK) {
        dev_ctx->info.segment_group = 0;
        zxlogf(TRACE, "%s Unable to read _SEG for '%s' (%d), assuming segment group 0.\n",
               kLogTag, dev_ctx->name, status);
    }

    // If an MCFG is found for the given segment group this root has then we'll
    // cache it for later pciroot operations and use its information to populate
    // any fields missing via _BBN / _SEG.
    auto& pinfo = dev_ctx->info;
    memcpy(pinfo.name, dev_ctx->name, sizeof(pinfo.name));
    pci_mcfg_allocation_t mcfg_alloc;
    status = pci_get_segment_mcfg_alloc(dev_ctx->info.segment_group, &mcfg_alloc);
    if (status == ZX_OK) {
        // Do the bus values make sense?
        if (found_bbn && mcfg_alloc.start_bus_num != pinfo.start_bus_num) {
            zxlogf(ERROR,
                   "%s: conflicting base bus num for '%s', _BBN reports %u and MCFG reports %u\n",
                   kLogTag, dev_ctx->name, pinfo.start_bus_num, mcfg_alloc.start_bus_num);
        }

        // Do the segment values make sense?
        if (pinfo.segment_group != 0 && pinfo.segment_group != mcfg_alloc.segment_group) {
            zxlogf(ERROR,
                   "%s: conflicting segment group for '%s', _BBN reports %u and MCFG reports %u\n",
                   kLogTag, dev_ctx->name, pinfo.segment_group, mcfg_alloc.segment_group);
        }

        // Since we have an ecam its metadata will replace anything defined in the ACPI tables.
        pinfo.segment_group = mcfg_alloc.segment_group;
        pinfo.start_bus_num = mcfg_alloc.start_bus_num;
        pinfo.end_bus_num = mcfg_alloc.end_bus_num;

        // The bus driver needs a VMO representing the entire ecam region so it can map it in.
        // The range from start_bus_num to end_bus_num is inclusive.
        size_t ecam_size = (pinfo.end_bus_num - pinfo.start_bus_num + 1) * PCIE_ECAM_BYTES_PER_BUS;
        zx_paddr_t vmo_base = mcfg_alloc.base_address +
                              (pinfo.start_bus_num * PCIE_ECAM_BYTES_PER_BUS);
        // Please do not use get_root_resource() in new code. See ZX-1467.
        status = zx_vmo_create_physical(get_root_resource(), vmo_base, ecam_size, &pinfo.ecam_vmo);
        if (status != ZX_OK) {
            zxlogf(ERROR, "couldn't create VMO for ecam, mmio cfg will not work: %d!\n", status);
            return status;
        }
    }

    if (zxlog_level_enabled(TRACE)) {
        printf("%s %s { acpi_obj(%p), bus range: %u:%u, segment: %u }\n", kLogTag,
               dev_ctx->name, dev_ctx->acpi_object, pinfo.start_bus_num, pinfo.end_bus_num,
               pinfo.segment_group);
        if (pinfo.ecam_vmo != ZX_HANDLE_INVALID) {
            printf("%s ecam base %#" PRIxPTR "\n", kLogTag, mcfg_alloc.base_address);
        }
    }

    // These are cached here to work around dev_ctx potentially going out of scope
    // after device_add in the event that unbind/release are called from the DDK. See
    // the below TODO for more information.
    char name[5];
    uint8_t last_pci_bbn = dev_ctx->info.start_bus_num;
    memcpy(name, dev_ctx->name, sizeof(name));

    status = Pciroot::Create(std::move(dev_ctx), parent, ctx->platform_bus, name);
    if (status != ZX_OK) {
        zxlogf(ERROR, "%s failed to add pciroot device for '%s': %d\n",
               kLogTag, dev_ctx->name, status);
    } else {
        // devmgr owns the ctx pointer now so release it from the uptr
        __UNUSED auto p = dev_ctx.release();

        // TODO(cja): these support the legacy-ish ACPI nhlt table handling that will need to be
        // updated in the future.
        ctx->found_pci = true;
        ctx->last_pci = last_pci_bbn;
        zxlogf(INFO, "%s published pciroot '%s'\n", kLogTag, name);
    }

    return status;
}