// Copyright 2016 The Fuchsia Authors
// Copyright (c) 2016, Google, Inc. All rights reserved
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include <assert.h>
#include <zircon/compiler.h>
#include <debug.h>
#include <err.h>
#include <inttypes.h>
#include <lk/init.h>
#include <dev/interrupt.h>
#include <string.h>
#include <trace.h>
#include <platform.h>
#include <vm/vm.h>

#include <dev/pci_config.h>
#include <dev/pcie_bridge.h>

#include <fbl/alloc_checker.h>

using fbl::AutoLock;

#define LOCAL_TRACE 0

PcieBridge::PcieBridge(PcieBusDriver& bus_drv, uint bus_id, uint dev_id, uint func_id, uint mbus_id)
    : PcieDevice(bus_drv, bus_id, dev_id, func_id, true),
      PcieUpstreamNode(bus_drv, PcieUpstreamNode::Type::BRIDGE, mbus_id) {
    /* Assign the driver-wide region pool to this bridge's allocators. */
    DEBUG_ASSERT(driver().region_bookkeeping() != nullptr);
    pf_mmio_regions_.SetRegionPool(driver().region_bookkeeping());
    mmio_lo_regions_.SetRegionPool(driver().region_bookkeeping());
    mmio_hi_regions_.SetRegionPool(driver().region_bookkeeping());
    pio_regions_.SetRegionPool(driver().region_bookkeeping());
}

fbl::RefPtr<PcieDevice> PcieBridge::Create(PcieUpstreamNode& upstream,
                                            uint dev_id,
                                            uint func_id,
                                            uint managed_bus_id) {
    fbl::AllocChecker ac;
    auto raw_bridge = new (&ac) PcieBridge(upstream.driver(),
                                           upstream.managed_bus_id(), dev_id, func_id,
                                           managed_bus_id);
    if (!ac.check()) {
        DEBUG_ASSERT(raw_bridge == nullptr);
        TRACEF("Out of memory attemping to create PCIe bridge %02x:%02x.%01x.\n",
                upstream.managed_bus_id(), dev_id, func_id);
        return nullptr;
    }

    auto bridge = fbl::AdoptRef(static_cast<PcieDevice*>(raw_bridge));
    zx_status_t res = raw_bridge->Init(upstream);
    if (res != ZX_OK) {
        TRACEF("Failed to initialize PCIe bridge %02x:%02x.%01x. (res %d)\n",
                upstream.managed_bus_id(), dev_id, func_id, res);
        return nullptr;
    }

    return bridge;
}

zx_status_t PcieBridge::Init(PcieUpstreamNode& upstream) {
    AutoLock dev_lock(&dev_lock_);

    // Initialize the device portion of ourselves first.
    zx_status_t res = PcieDevice::InitLocked(upstream);
    if (res != ZX_OK)
        return res;

    // Sanity checks of bus allocation.
    //
    // TODO(johngro) : Strengthen sanity checks around bridge topology and
    // handle the need to reconfigure bridge topology if a bridge happens to be
    // misconfigured.  Right now, we just assume that the BIOS/Bootloader has
    // taken care of bridge configuration.  In the short term, it would be good
    // to add some protection against cycles in the bridge configuration which
    // could lead to infinite recursion.
    uint primary_id = cfg_->Read(PciConfig::kPrimaryBusId);
    uint secondary_id = cfg_->Read(PciConfig::kSecondaryBusId);

    if (primary_id == secondary_id) {
        TRACEF("PCI-to-PCI bridge detected at %02x:%02x.%01x claims to be bridged to itsef "
               "(primary %02x == secondary %02x)... skipping scan.\n",
               bus_id_, dev_id_, func_id_, primary_id, secondary_id);
        return ZX_ERR_BAD_STATE;
    }

    if (primary_id != bus_id_) {
        TRACEF("PCI-to-PCI bridge detected at %02x:%02x.%01x has invalid primary bus id "
               "(%02x)... skipping scan.\n",
               bus_id_, dev_id_, func_id_, primary_id);
        return ZX_ERR_BAD_STATE;
    }

    if (secondary_id != managed_bus_id()) {
        TRACEF("PCI-to-PCI bridge detected at %02x:%02x.%01x has invalid secondary bus id "
               "(%02x)... skipping scan.\n",
               bus_id_, dev_id_, func_id_, secondary_id);
        return ZX_ERR_BAD_STATE;
    }

    // Parse the state of its I/O and Memory windows.
    res = ParseBusWindowsLocked();
    if (res != ZX_OK)
        return res;

    // Things went well, flag the device as plugged in and link ourselves up to
    // the graph.
    plugged_in_ = true;
    driver().LinkDeviceToUpstream(*this, upstream);

    // Release the device lock, then recurse and scan for downstream devices.
    dev_lock.release();
    ScanDownstream();
    return res;
}

zx_status_t PcieBridge::ParseBusWindowsLocked() {
    DEBUG_ASSERT(dev_lock_.IsHeld());

    // Parse the currently configured windows used to determine MMIO/PIO
    // forwarding policy for this bridge.
    //
    // See The PCI-to-PCI Bridge Architecture Specification Revision 1.2,
    // section 3.2.5 and chapter 4 for detail.
    uint32_t base, limit;

    // I/O window
    base  = cfg_->Read(PciConfig::kIoBase);
    limit = cfg_->Read(PciConfig::kIoLimit);

    supports_32bit_pio_ = ((base & 0xF) == 0x1) && ((base & 0xF) == (limit& 0xF));
    io_base_  = (base & ~0xF) << 8;
    io_limit_ = (limit << 8) | 0xFFF;
    if (supports_32bit_pio_) {
        io_base_  |= static_cast<uint32_t>(cfg_->Read(PciConfig::kIoBaseUpper)) << 16;
        io_limit_ |= static_cast<uint32_t>(cfg_->Read(PciConfig::kIoLimitUpper)) << 16;
    }

    // Non-prefetchable memory window
    mem_base_  = (static_cast<uint32_t>(cfg_->Read(PciConfig::kMemoryBase)) << 16)
                       & ~0xFFFFF;
    mem_limit_ = (static_cast<uint32_t>(cfg_->Read(PciConfig::kMemoryLimit)) << 16)
                       | 0xFFFFF;

    // Prefetchable memory window
    base  = cfg_->Read(PciConfig::kPrefetchableMemoryBase);
    limit = cfg_->Read(PciConfig::kPrefetchableMemoryLimit);

    bool supports_64bit_pf_mem = ((base & 0xF) == 0x1) && ((base & 0xF) == (limit& 0xF));
    pf_mem_base_  = (base & ~0xF) << 16;
    pf_mem_limit_ = (limit << 16) | 0xFFFFF;
    if (supports_64bit_pf_mem) {
        pf_mem_base_  |=
            static_cast<uint64_t>(cfg_->Read(PciConfig::kPrefetchableMemoryBaseUpper)) << 32;
        pf_mem_limit_ |=
            static_cast<uint64_t>(cfg_->Read(PciConfig::kPrefetchableMemoryLimitUpper)) << 32;
    }

    return ZX_OK;
}

void PcieBridge::Dump() const {
    PcieDevice::Dump();

    printf("\tbridge managed bus id %#02x\n", managed_bus_id());
    printf("\tio base %#x limit %#x\n", io_base(), io_limit());
    printf("\tmem base %#x limit %#x\n", mem_base(), mem_limit());
    printf("\tprefectable base %#" PRIx64 " limit %#" PRIx64 "\n", pf_mem_base(), pf_mem_limit());
}

void PcieBridge::Unplug() {
    PcieDevice::Unplug();
    PcieUpstreamNode::UnplugDownstream();
}

zx_status_t PcieBridge::AllocateBars() {
    AutoLock dev_lock(&dev_lock_);

    // Start by making sure we can allocate our bridge windows.
    zx_status_t res = AllocateBridgeWindowsLocked();
    if (res != ZX_OK)
        return res;

    // Now, attempt to allocate our device BARs.
    res = PcieDevice::AllocateBarsLocked();
    if (res != ZX_OK)
        return res;

    // Great, we are good to go.  Leave our device lock and attempt to allocate
    // our downstream devices' resources.
    dev_lock.release();
    PcieUpstreamNode::AllocateDownstreamBars();
    return ZX_OK;
}

zx_status_t PcieBridge::AllocateBridgeWindowsLocked() {
    zx_status_t ret;
    DEBUG_ASSERT(dev_lock_.IsHeld());

    // Hold a reference to our upstream node while we do this.  If we cannot
    // obtain a reference, then our upstream node has become unplugged and we
    // should just fail out now.
    auto upstream = GetUpstream();
    if (upstream == nullptr)
        return ZX_ERR_UNAVAILABLE;

    // We are configuring a bridge.  We need to be able to allocate the MMIO and
    // PIO regions this bridge is configured to manage.  Currently, we don't
    // support re-allocating a bridge's MMIO/PIO windows.
    //
    // TODO(johngro) : support dynamic configuration of bridge windows.  Its
    // going to be important when we need to support hot-plugging.  See ZX-322
    //
    if (io_base_ <= io_limit_) {
        uint64_t size = static_cast<uint64_t>(io_limit_) - io_base_ + 1;
        ret = upstream->pio_regions().GetRegion({ .base = io_base_, .size = size }, pio_window_);

        if (ret != ZX_OK) {
            TRACEF("Failed to allocate bridge PIO window [0x%08x, 0x%08x]\n", io_base_, io_limit_);
            return ret;
        }

        DEBUG_ASSERT(pio_window_ != nullptr);
        pio_regions().AddRegion(*pio_window_);
    }

    if (mem_base_ <= mem_limit_) {
        uint64_t size = mem_limit_ - mem_base_ + 1;
        ret = upstream->mmio_lo_regions().GetRegion({ .base = mem_base_, .size = size },
                                                    mmio_window_);

        if (ret != ZX_OK) {
            TRACEF("Failed to allocate bridge MMIO window [0x%08x, 0x%08x]\n",
                    mem_base_, mem_limit_);
            return ret;
        }

        DEBUG_ASSERT(mmio_window_ != nullptr);
        mmio_lo_regions().AddRegion(*mmio_window_);
    }

    if (pf_mem_base_ <= pf_mem_limit_) {
        uint64_t size = pf_mem_limit_ - pf_mem_base_ + 1;

        // Attempt to allocate out of the upstream's prefetchable region.
        ret = upstream->pf_mmio_regions().GetRegion({ .base = pf_mem_base_, .size = size },
                                                    pf_mmio_window_);
        if (ret != ZX_OK) {
            // We failed. If it's the root bridge try to allocate from its MMIO regions.
            if (upstream->type() == PcieUpstreamNode::Type::ROOT) {
                ret = upstream->mmio_lo_regions().GetRegion({ .base = pf_mem_base_, .size = size },
                                                            pf_mmio_window_);
                if (ret != ZX_OK) {
                    ret = upstream->mmio_hi_regions().GetRegion({ .base = pf_mem_base_, .size = size },
                                                                pf_mmio_window_);
                }
            }
        }

        if (ret != ZX_OK) {
            TRACEF("Failed to allocate bridge prefetcable MMIO window "
                   "[%#" PRIx64 ", %#" PRIx64 "]\n",
                    pf_mem_base_, pf_mem_limit_);
            return ret;
        }

        DEBUG_ASSERT(pf_mmio_window_ != nullptr);
        pf_mmio_regions().AddRegion(*pf_mmio_window_);
    }

    return ZX_OK;
}

void PcieBridge::Disable() {
    DEBUG_ASSERT(!dev_lock_.IsHeld());

    // Immediately enter the device lock and enter the disabled state.  We want
    // to be outside of the device lock as we disable our downstream devices,
    // but we don't want any new devices to be able to plug into us as we do so.
    {
        AutoLock dev_lock(&dev_lock_);
        disabled_ = true;
    }

    // Start by disabling all of our downstream devices.  This should prevent
    // the from bothering us moving forward.  Do not hold the device lock while
    // we do this.
    PcieUpstreamNode::DisableDownstream();

    // Enter the device lock again and finish shooting ourselves in the head.
    {
        AutoLock dev_lock(&dev_lock_);

        // Disable the device portion of ourselves.
        PcieDevice::DisableLocked();

        // Close all of our IO windows at the HW level and update the internal
        // bookkeeping to indicate that they are closed.
        cfg_->Write(PciConfig::kIoBase, 0xF0);
        cfg_->Write(PciConfig::kIoLimit, 0);
        cfg_->Write(PciConfig::kIoBaseUpper, 0);
        cfg_->Write(PciConfig::kIoLimitUpper, 0);

        cfg_->Write(PciConfig::kMemoryBase, 0xFFF0);
        cfg_->Write(PciConfig::kMemoryLimit, 0);

        cfg_->Write(PciConfig::kPrefetchableMemoryBase, 0xFFF0);
        cfg_->Write(PciConfig::kPrefetchableMemoryLimit, 0);
        cfg_->Write(PciConfig::kPrefetchableMemoryBaseUpper, 0);
        cfg_->Write(PciConfig::kPrefetchableMemoryLimitUpper, 0);

        pf_mem_limit_ = mem_limit_ = io_limit_ = 0u;
        pf_mem_base_  = mem_base_  = io_base_  = 1u;

        // Release our internal bookkeeping
        mmio_lo_regions().Reset();
        mmio_hi_regions().Reset();
        pio_regions().Reset();

        mmio_window_.reset();
        pio_window_.reset();
    }
}