/*
 * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/MACAddress.h>
#include <Kernel/Debug.h>
#include <Kernel/Net/E1000NetworkAdapter.h>
#include <Kernel/PCI/IDs.h>

namespace Kernel {

#define REG_CTRL 0x0000
#define REG_STATUS 0x0008
#define REG_EEPROM 0x0014
#define REG_CTRL_EXT 0x0018
#define REG_INTERRUPT_CAUSE_READ 0x00C0
#define REG_INTERRUPT_RATE 0x00C4
#define REG_INTERRUPT_MASK_SET 0x00D0
#define REG_INTERRUPT_MASK_CLEAR 0x00D8
#define REG_RCTRL 0x0100
#define REG_RXDESCLO 0x2800
#define REG_RXDESCHI 0x2804
#define REG_RXDESCLEN 0x2808
#define REG_RXDESCHEAD 0x2810
#define REG_RXDESCTAIL 0x2818
#define REG_TCTRL 0x0400
#define REG_TXDESCLO 0x3800
#define REG_TXDESCHI 0x3804
#define REG_TXDESCLEN 0x3808
#define REG_TXDESCHEAD 0x3810
#define REG_TXDESCTAIL 0x3818
#define REG_RDTR 0x2820             // RX Delay Timer Register
#define REG_RXDCTL 0x3828           // RX Descriptor Control
#define REG_RADV 0x282C             // RX Int. Absolute Delay Timer
#define REG_RSRPD 0x2C00            // RX Small Packet Detect Interrupt
#define REG_TIPG 0x0410             // Transmit Inter Packet Gap
#define ECTRL_SLU 0x40              //set link up
#define RCTL_EN (1 << 1)            // Receiver Enable
#define RCTL_SBP (1 << 2)           // Store Bad Packets
#define RCTL_UPE (1 << 3)           // Unicast Promiscuous Enabled
#define RCTL_MPE (1 << 4)           // Multicast Promiscuous Enabled
#define RCTL_LPE (1 << 5)           // Long Packet Reception Enable
#define RCTL_LBM_NONE (0 << 6)      // No Loopback
#define RCTL_LBM_PHY (3 << 6)       // PHY or external SerDesc loopback
#define RTCL_RDMTS_HALF (0 << 8)    // Free Buffer Threshold is 1/2 of RDLEN
#define RTCL_RDMTS_QUARTER (1 << 8) // Free Buffer Threshold is 1/4 of RDLEN
#define RTCL_RDMTS_EIGHTH (2 << 8)  // Free Buffer Threshold is 1/8 of RDLEN
#define RCTL_MO_36 (0 << 12)        // Multicast Offset - bits 47:36
#define RCTL_MO_35 (1 << 12)        // Multicast Offset - bits 46:35
#define RCTL_MO_34 (2 << 12)        // Multicast Offset - bits 45:34
#define RCTL_MO_32 (3 << 12)        // Multicast Offset - bits 43:32
#define RCTL_BAM (1 << 15)          // Broadcast Accept Mode
#define RCTL_VFE (1 << 18)          // VLAN Filter Enable
#define RCTL_CFIEN (1 << 19)        // Canonical Form Indicator Enable
#define RCTL_CFI (1 << 20)          // Canonical Form Indicator Bit Value
#define RCTL_DPF (1 << 22)          // Discard Pause Frames
#define RCTL_PMCF (1 << 23)         // Pass MAC Control Frames
#define RCTL_SECRC (1 << 26)        // Strip Ethernet CRC

// Buffer Sizes
#define RCTL_BSIZE_256 (3 << 16)
#define RCTL_BSIZE_512 (2 << 16)
#define RCTL_BSIZE_1024 (1 << 16)
#define RCTL_BSIZE_2048 (0 << 16)
#define RCTL_BSIZE_4096 ((3 << 16) | (1 << 25))
#define RCTL_BSIZE_8192 ((2 << 16) | (1 << 25))
#define RCTL_BSIZE_16384 ((1 << 16) | (1 << 25))

// Transmit Command

#define CMD_EOP (1 << 0)  // End of Packet
#define CMD_IFCS (1 << 1) // Insert FCS
#define CMD_IC (1 << 2)   // Insert Checksum
#define CMD_RS (1 << 3)   // Report Status
#define CMD_RPS (1 << 4)  // Report Packet Sent
#define CMD_VLE (1 << 6)  // VLAN Packet Enable
#define CMD_IDE (1 << 7)  // Interrupt Delay Enable

// TCTL Register

#define TCTL_EN (1 << 1)      // Transmit Enable
#define TCTL_PSP (1 << 3)     // Pad Short Packets
#define TCTL_CT_SHIFT 4       // Collision Threshold
#define TCTL_COLD_SHIFT 12    // Collision Distance
#define TCTL_SWXOFF (1 << 22) // Software XOFF Transmission
#define TCTL_RTLC (1 << 24)   // Re-transmit on Late Collision

#define TSTA_DD (1 << 0) // Descriptor Done
#define TSTA_EC (1 << 1) // Excess Collisions
#define TSTA_LC (1 << 2) // Late Collision
#define LSTA_TU (1 << 3) // Transmit Underrun

// STATUS Register

#define STATUS_FD 0x01
#define STATUS_LU 0x02
#define STATUS_TXOFF 0x08
#define STATUS_SPEED 0xC0
#define STATUS_SPEED_10MB 0x00
#define STATUS_SPEED_100MB 0x40
#define STATUS_SPEED_1000MB1 0x80
#define STATUS_SPEED_1000MB2 0xC0

// Interrupt Masks

#define INTERRUPT_TXDW (1 << 0)
#define INTERRUPT_TXQE (1 << 1)
#define INTERRUPT_LSC (1 << 2)
#define INTERRUPT_RXSEQ (1 << 3)
#define INTERRUPT_RXDMT0 (1 << 4)
#define INTERRUPT_RXO (1 << 6)
#define INTERRUPT_RXT0 (1 << 7)
#define INTERRUPT_MDAC (1 << 9)
#define INTERRUPT_RXCFG (1 << 10)
#define INTERRUPT_PHYINT (1 << 12)
#define INTERRUPT_TXD_LOW (1 << 15)
#define INTERRUPT_SRPD (1 << 16)

// https://www.intel.com/content/dam/doc/manual/pci-pci-x-family-gbe-controllers-software-dev-manual.pdf Section 5.2
static bool is_valid_device_id(u16 device_id)
{
    // FIXME: It would be nice to distinguish which particular device it is.
    //        Especially since it's needed to determine which registers we can access.
    //        The reason I haven't done it now is because there's some IDs with multiple devices
    //        and some devices with multiple IDs.
    switch (device_id) {
    case 0x1019: // 82547EI-A0, 82547EI-A1, 82547EI-B0, 82547GI-B0
    case 0x101A: // 82547EI-B0
    case 0x1010: // 82546EB-A1
    case 0x1012: // 82546EB-A1
    case 0x101D: // 82546EB-A1
    case 0x1079: // 82546GB-B0
    case 0x107A: // 82546GB-B0
    case 0x107B: // 82546GB-B0
    case 0x100F: // 82545EM-A
    case 0x1011: // 82545EM-A
    case 0x1026: // 82545GM-B
    case 0x1027: // 82545GM-B
    case 0x1028: // 82545GM-B
    case 0x1107: // 82544EI-A4
    case 0x1112: // 82544GC-A4
    case 0x1013: // 82541EI-A0, 82541EI-B0
    case 0x1018: // 82541EI-B0
    case 0x1076: // 82541GI-B1, 82541PI-C0
    case 0x1077: // 82541GI-B1
    case 0x1078: // 82541ER-C0
    case 0x1017: // 82540EP-A
    case 0x1016: // 82540EP-A
    case 0x100E: // 82540EM-A
    case 0x1015: // 82540EM-A
        return true;
    default:
        return false;
    }
}

UNMAP_AFTER_INIT void E1000NetworkAdapter::detect()
{
    PCI::enumerate([&](const PCI::Address& address, PCI::ID id) {
        if (address.is_null())
            return;
        if (id.vendor_id != (u16)PCIVendorID::Intel)
            return;
        if (!is_valid_device_id(id.device_id))
            return;
        u8 irq = PCI::get_interrupt_line(address);
        [[maybe_unused]] auto& unused = adopt_ref(*new E1000NetworkAdapter(address, irq)).leak_ref();
    });
}

UNMAP_AFTER_INIT E1000NetworkAdapter::E1000NetworkAdapter(PCI::Address address, u8 irq)
    : PCI::Device(address, irq)
    , m_io_base(PCI::get_BAR1(pci_address()) & ~1)
    , m_rx_descriptors_region(MM.allocate_contiguous_kernel_region(page_round_up(sizeof(e1000_rx_desc) * number_of_rx_descriptors + 16), "E1000 RX", Region::Access::Read | Region::Access::Write))
    , m_tx_descriptors_region(MM.allocate_contiguous_kernel_region(page_round_up(sizeof(e1000_tx_desc) * number_of_tx_descriptors + 16), "E1000 TX", Region::Access::Read | Region::Access::Write))
{
    set_interface_name("e1k");

    dmesgln("E1000: Found @ {}", pci_address());

    enable_bus_mastering(pci_address());

    size_t mmio_base_size = PCI::get_BAR_space_size(pci_address(), 0);
    m_mmio_region = MM.allocate_kernel_region(PhysicalAddress(page_base_of(PCI::get_BAR0(pci_address()))), page_round_up(mmio_base_size), "E1000 MMIO", Region::Access::Read | Region::Access::Write, Region::Cacheable::No);
    m_mmio_base = m_mmio_region->vaddr();
    m_use_mmio = true;
    m_interrupt_line = PCI::get_interrupt_line(pci_address());
    dmesgln("E1000: port base: {}", m_io_base);
    dmesgln("E1000: MMIO base: {}", PhysicalAddress(PCI::get_BAR0(pci_address()) & 0xfffffffc));
    dmesgln("E1000: MMIO base size: {} bytes", mmio_base_size);
    dmesgln("E1000: Interrupt line: {}", m_interrupt_line);
    detect_eeprom();
    dmesgln("E1000: Has EEPROM? {}", m_has_eeprom);
    read_mac_address();
    const auto& mac = mac_address();
    dmesgln("E1000: MAC address: {}", mac.to_string());

    u32 flags = in32(REG_CTRL);
    out32(REG_CTRL, flags | ECTRL_SLU);

    out32(REG_INTERRUPT_RATE, 6000); // Interrupt rate of 1.536 milliseconds

    initialize_rx_descriptors();
    initialize_tx_descriptors();

    out32(REG_INTERRUPT_MASK_SET, INTERRUPT_LSC | INTERRUPT_RXT0 | INTERRUPT_RXO);
    in32(REG_INTERRUPT_CAUSE_READ);

    enable_irq();
}

UNMAP_AFTER_INIT E1000NetworkAdapter::~E1000NetworkAdapter()
{
}

void E1000NetworkAdapter::handle_irq(const RegisterState&)
{
    u32 status = in32(REG_INTERRUPT_CAUSE_READ);

    m_entropy_source.add_random_event(status);

    if (status & INTERRUPT_LSC) {
        u32 flags = in32(REG_CTRL);
        out32(REG_CTRL, flags | ECTRL_SLU);
    }
    if (status & INTERRUPT_RXDMT0) {
        // Threshold OK?
    }
    if (status & INTERRUPT_RXO) {
        dbgln_if(E1000_DEBUG, "E1000: RX buffer overrun");
    }
    if (status & INTERRUPT_RXT0) {
        receive();
    }

    m_wait_queue.wake_all();

    out32(REG_INTERRUPT_CAUSE_READ, 0xffffffff);
}

UNMAP_AFTER_INIT void E1000NetworkAdapter::detect_eeprom()
{
    out32(REG_EEPROM, 0x1);
    for (int i = 0; i < 999; ++i) {
        u32 data = in32(REG_EEPROM);
        if (data & 0x10) {
            m_has_eeprom = true;
            return;
        }
    }
    m_has_eeprom = false;
}

UNMAP_AFTER_INIT u32 E1000NetworkAdapter::read_eeprom(u8 address)
{
    u16 data = 0;
    u32 tmp = 0;
    if (m_has_eeprom) {
        out32(REG_EEPROM, ((u32)address << 8) | 1);
        while (!((tmp = in32(REG_EEPROM)) & (1 << 4)))
            ;
    } else {
        out32(REG_EEPROM, ((u32)address << 2) | 1);
        while (!((tmp = in32(REG_EEPROM)) & (1 << 1)))
            ;
    }
    data = (tmp >> 16) & 0xffff;
    return data;
}

UNMAP_AFTER_INIT void E1000NetworkAdapter::read_mac_address()
{
    if (m_has_eeprom) {
        MACAddress mac {};
        u32 tmp = read_eeprom(0);
        mac[0] = tmp & 0xff;
        mac[1] = tmp >> 8;
        tmp = read_eeprom(1);
        mac[2] = tmp & 0xff;
        mac[3] = tmp >> 8;
        tmp = read_eeprom(2);
        mac[4] = tmp & 0xff;
        mac[5] = tmp >> 8;
        set_mac_address(mac);
    } else {
        VERIFY_NOT_REACHED();
    }
}

bool E1000NetworkAdapter::link_up()
{
    return (in32(REG_STATUS) & STATUS_LU);
}

UNMAP_AFTER_INIT void E1000NetworkAdapter::initialize_rx_descriptors()
{
    auto* rx_descriptors = (e1000_tx_desc*)m_rx_descriptors_region->vaddr().as_ptr();
    for (size_t i = 0; i < number_of_rx_descriptors; ++i) {
        auto& descriptor = rx_descriptors[i];
        auto region = MM.allocate_contiguous_kernel_region(8192, "E1000 RX buffer", Region::Access::Read | Region::Access::Write);
        VERIFY(region);
        m_rx_buffers_regions.append(region.release_nonnull());
        descriptor.addr = m_rx_buffers_regions[i].physical_page(0)->paddr().get();
        descriptor.status = 0;
    }

    out32(REG_RXDESCLO, m_rx_descriptors_region->physical_page(0)->paddr().get());
    out32(REG_RXDESCHI, 0);
    out32(REG_RXDESCLEN, number_of_rx_descriptors * sizeof(e1000_rx_desc));
    out32(REG_RXDESCHEAD, 0);
    out32(REG_RXDESCTAIL, number_of_rx_descriptors - 1);

    out32(REG_RCTRL, RCTL_EN | RCTL_SBP | RCTL_UPE | RCTL_MPE | RCTL_LBM_NONE | RTCL_RDMTS_HALF | RCTL_BAM | RCTL_SECRC | RCTL_BSIZE_8192);
}

UNMAP_AFTER_INIT void E1000NetworkAdapter::initialize_tx_descriptors()
{
    auto* tx_descriptors = (e1000_tx_desc*)m_tx_descriptors_region->vaddr().as_ptr();
    for (size_t i = 0; i < number_of_tx_descriptors; ++i) {
        auto& descriptor = tx_descriptors[i];
        auto region = MM.allocate_contiguous_kernel_region(8192, "E1000 TX buffer", Region::Access::Read | Region::Access::Write);
        VERIFY(region);
        m_tx_buffers_regions.append(region.release_nonnull());
        descriptor.addr = m_tx_buffers_regions[i].physical_page(0)->paddr().get();
        descriptor.cmd = 0;
    }

    out32(REG_TXDESCLO, m_tx_descriptors_region->physical_page(0)->paddr().get());
    out32(REG_TXDESCHI, 0);
    out32(REG_TXDESCLEN, number_of_tx_descriptors * sizeof(e1000_tx_desc));
    out32(REG_TXDESCHEAD, 0);
    out32(REG_TXDESCTAIL, 0);

    out32(REG_TCTRL, in32(REG_TCTRL) | TCTL_EN | TCTL_PSP);
    out32(REG_TIPG, 0x0060200A);
}

void E1000NetworkAdapter::out8(u16 address, u8 data)
{
    dbgln_if(E1000_DEBUG, "E1000: OUT8 {:#02x} @ {:#04x}", data, address);
    if (m_use_mmio) {
        auto* ptr = (volatile u8*)(m_mmio_base.get() + address);
        *ptr = data;
        return;
    }
    m_io_base.offset(address).out(data);
}

void E1000NetworkAdapter::out16(u16 address, u16 data)
{
    dbgln_if(E1000_DEBUG, "E1000: OUT16 {:#04x} @ {:#04x}", data, address);
    if (m_use_mmio) {
        auto* ptr = (volatile u16*)(m_mmio_base.get() + address);
        *ptr = data;
        return;
    }
    m_io_base.offset(address).out(data);
}

void E1000NetworkAdapter::out32(u16 address, u32 data)
{
    dbgln_if(E1000_DEBUG, "E1000: OUT32 {:#08x} @ {:#04x}", data, address);
    if (m_use_mmio) {
        auto* ptr = (volatile u32*)(m_mmio_base.get() + address);
        *ptr = data;
        return;
    }
    m_io_base.offset(address).out(data);
}

u8 E1000NetworkAdapter::in8(u16 address)
{
    dbgln_if(E1000_DEBUG, "E1000: IN8 @ {:#04x}", address);
    if (m_use_mmio)
        return *(volatile u8*)(m_mmio_base.get() + address);
    return m_io_base.offset(address).in<u8>();
}

u16 E1000NetworkAdapter::in16(u16 address)
{
    dbgln_if(E1000_DEBUG, "E1000: IN16 @ {:#04x}", address);
    if (m_use_mmio)
        return *(volatile u16*)(m_mmio_base.get() + address);
    return m_io_base.offset(address).in<u16>();
}

u32 E1000NetworkAdapter::in32(u16 address)
{
    dbgln_if(E1000_DEBUG, "E1000: IN32 @ {:#04x}", address);
    if (m_use_mmio)
        return *(volatile u32*)(m_mmio_base.get() + address);
    return m_io_base.offset(address).in<u32>();
}

void E1000NetworkAdapter::send_raw(ReadonlyBytes payload)
{
    disable_irq();
    size_t tx_current = in32(REG_TXDESCTAIL) % number_of_tx_descriptors;
    dbgln_if(E1000_DEBUG, "E1000: Sending packet ({} bytes)", payload.size());
    auto* tx_descriptors = (e1000_tx_desc*)m_tx_descriptors_region->vaddr().as_ptr();
    auto& descriptor = tx_descriptors[tx_current];
    VERIFY(payload.size() <= 8192);
    auto* vptr = (void*)m_tx_buffers_regions[tx_current].vaddr().as_ptr();
    memcpy(vptr, payload.data(), payload.size());
    descriptor.length = payload.size();
    descriptor.status = 0;
    descriptor.cmd = CMD_EOP | CMD_IFCS | CMD_RS;
    dbgln_if(E1000_DEBUG, "E1000: Using tx descriptor {} (head is at {})", tx_current, in32(REG_TXDESCHEAD));
    tx_current = (tx_current + 1) % number_of_tx_descriptors;
    cli();
    enable_irq();
    out32(REG_TXDESCTAIL, tx_current);
    for (;;) {
        if (descriptor.status) {
            sti();
            break;
        }
        m_wait_queue.wait_forever("E1000NetworkAdapter");
    }
    dbgln_if(E1000_DEBUG, "E1000: Sent packet, status is now {:#02x}!", (u8)descriptor.status);
}

void E1000NetworkAdapter::receive()
{
    auto* rx_descriptors = (e1000_tx_desc*)m_rx_descriptors_region->vaddr().as_ptr();
    u32 rx_current;
    for (;;) {
        rx_current = in32(REG_RXDESCTAIL) % number_of_rx_descriptors;
        rx_current = (rx_current + 1) % number_of_rx_descriptors;
        if (!(rx_descriptors[rx_current].status & 1))
            break;
        auto* buffer = m_rx_buffers_regions[rx_current].vaddr().as_ptr();
        u16 length = rx_descriptors[rx_current].length;
        VERIFY(length <= 8192);
        dbgln_if(E1000_DEBUG, "E1000: Received 1 packet @ {:p} ({} bytes)", buffer, length);
        did_receive({ buffer, length });
        rx_descriptors[rx_current].status = 0;
        out32(REG_RXDESCTAIL, rx_current);
    }
}

}