/*
 * Copyright (c) 2020, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <Kernel/Arch/x86/IO.h>
#include <Kernel/Devices/HID/I8042Controller.h>
#include <Kernel/Devices/HID/PS2KeyboardDevice.h>
#include <Kernel/Devices/HID/PS2MouseDevice.h>
#include <Kernel/Devices/HID/VMWareMouseDevice.h>
#include <Kernel/Sections.h>

namespace Kernel {

UNMAP_AFTER_INIT NonnullRefPtr<I8042Controller> I8042Controller::initialize()
{
    return adopt_ref(*new I8042Controller());
}

RefPtr<MouseDevice> I8042Controller::mouse() const
{
    return m_mouse_device;
}
RefPtr<KeyboardDevice> I8042Controller::keyboard() const
{
    return m_keyboard_device;
}

UNMAP_AFTER_INIT I8042Controller::I8042Controller()
{
}

UNMAP_AFTER_INIT void I8042Controller::detect_devices()
{
    u8 configuration;
    {
        SpinlockLocker lock(m_lock);

        drain_output_buffer();

        do_wait_then_write(I8042Port::Command, I8042Command::DisableFirstPS2Port);
        do_wait_then_write(I8042Port::Command, I8042Command::DisableSecondPS2Port); // ignored if it doesn't exist

        do_wait_then_write(I8042Port::Command, I8042Command::ReadConfiguration);
        configuration = do_wait_then_read(I8042Port::Buffer);
        do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
        configuration &= ~I8042ConfigurationFlag::FirstPS2PortInterrupt;
        configuration &= ~I8042ConfigurationFlag::SecondPS2PortInterrupt;
        do_wait_then_write(I8042Port::Buffer, configuration);

        m_is_dual_channel = (configuration & I8042ConfigurationFlag::SecondPS2PortClock) != 0;
        dbgln("I8042: {} channel controller", m_is_dual_channel ? "Dual" : "Single");

        // Perform controller self-test
        do_wait_then_write(I8042Port::Command, I8042Command::TestPS2Controller);
        if (do_wait_then_read(I8042Port::Buffer) == I8042Response::ControllerTestPassed) {
            // Restore configuration in case the controller reset
            do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
            do_wait_then_write(I8042Port::Buffer, configuration);
        } else {
            dbgln("I8042: Controller self test failed");
        }

        // Test ports and enable them if available
        do_wait_then_write(I8042Port::Command, I8042Command::TestFirstPS2Port);
        m_first_port_available = (do_wait_then_read(I8042Port::Buffer) == 0);

        if (m_first_port_available) {
            do_wait_then_write(I8042Port::Command, I8042Command::EnableFirstPS2Port);
            configuration |= I8042ConfigurationFlag::FirstPS2PortInterrupt;
            configuration &= ~I8042ConfigurationFlag::FirstPS2PortClock;
        } else {
            dbgln("I8042: Keyboard port not available");
        }

        drain_output_buffer();

        if (m_is_dual_channel) {
            do_wait_then_write(I8042Port::Command, I8042Command::TestSecondPS2Port);
            m_second_port_available = (do_wait_then_read(I8042Port::Buffer) == 0);
            if (m_second_port_available) {
                do_wait_then_write(I8042Port::Command, I8042Command::EnableSecondPS2Port);
                configuration |= I8042ConfigurationFlag::SecondPS2PortInterrupt;
                configuration &= ~I8042ConfigurationFlag::SecondPS2PortClock;
            } else {
                dbgln("I8042: Mouse port not available");
            }
        }

        // Enable IRQs for the ports that are usable
        if (m_first_port_available || m_second_port_available) {
            configuration &= ~I8042ConfigurationFlag::FirstPS2PortClock;
            configuration &= ~I8042ConfigurationFlag::SecondPS2PortClock;
            do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
            do_wait_then_write(I8042Port::Buffer, configuration);
        }
    }

    // Try to detect and initialize the devices
    if (m_first_port_available) {
        m_keyboard_device = PS2KeyboardDevice::try_to_initialize(*this);
        if (!m_keyboard_device) {
            dbgln("I8042: Keyboard device failed to initialize, disable");
            m_first_port_available = false;
            configuration &= ~I8042ConfigurationFlag::FirstPS2PortInterrupt;
            configuration |= I8042ConfigurationFlag::FirstPS2PortClock;
            SpinlockLocker lock(m_lock);
            do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
            do_wait_then_write(I8042Port::Buffer, configuration);
        }
    }
    if (m_second_port_available) {
        m_mouse_device = VMWareMouseDevice::try_to_initialize(*this);
        if (!m_mouse_device) {
            m_mouse_device = PS2MouseDevice::try_to_initialize(*this);
            if (!m_mouse_device) {
                dbgln("I8042: Mouse device failed to initialize, disable");
                m_second_port_available = false;
                configuration |= I8042ConfigurationFlag::SecondPS2PortClock;
                SpinlockLocker lock(m_lock);
                do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
                do_wait_then_write(I8042Port::Buffer, configuration);
            }
        }
    }

    // Enable IRQs after both are detected and initialized
    if (m_keyboard_device)
        m_keyboard_device->enable_interrupts();
    if (m_mouse_device)
        m_mouse_device->enable_interrupts();
}

bool I8042Controller::irq_process_input_buffer(HIDDevice::Type instrument_type)
{
    VERIFY(Processor::current_in_irq());

    u8 status = IO::in8(I8042Port::Status);
    if (!(status & I8042StatusFlag::OutputBuffer))
        return false;
    u8 byte = IO::in8(I8042Port::Buffer);
    if (instrument_type == HIDDevice::Type::Mouse) {
        VERIFY(m_mouse_device);
        static_cast<PS2MouseDevice&>(*m_mouse_device).irq_handle_byte_read(byte);
        return true;
    }
    if (instrument_type == HIDDevice::Type::Keyboard) {
        VERIFY(m_keyboard_device);
        static_cast<PS2KeyboardDevice&>(*m_keyboard_device).irq_handle_byte_read(byte);
        return true;
    }
    return false;
}

void I8042Controller::drain_output_buffer()
{
    for (;;) {
        u8 status = IO::in8(I8042Port::Status);
        if (!(status & I8042StatusFlag::OutputBuffer))
            return;
        IO::in8(I8042Port::Buffer);
    }
}

bool I8042Controller::do_reset_device(HIDDevice::Type device)
{
    VERIFY(device != HIDDevice::Type::Unknown);
    VERIFY(m_lock.is_locked());

    VERIFY(!Processor::current_in_irq());
    if (do_send_command(device, I8042Command::Reset) != I8042Response::Acknowledge)
        return false;
    // Wait until we get the self-test result
    return do_wait_then_read(I8042Port::Buffer) == I8042Response::Success;
}

u8 I8042Controller::do_send_command(HIDDevice::Type device, u8 command)
{
    VERIFY(device != HIDDevice::Type::Unknown);
    VERIFY(m_lock.is_locked());

    VERIFY(!Processor::current_in_irq());

    return do_write_to_device(device, command);
}

u8 I8042Controller::do_send_command(HIDDevice::Type device, u8 command, u8 data)
{
    VERIFY(device != HIDDevice::Type::Unknown);
    VERIFY(m_lock.is_locked());

    VERIFY(!Processor::current_in_irq());

    u8 response = do_write_to_device(device, command);
    if (response == I8042Response::Acknowledge)
        response = do_write_to_device(device, data);
    return response;
}

u8 I8042Controller::do_write_to_device(HIDDevice::Type device, u8 data)
{
    VERIFY(device != HIDDevice::Type::Unknown);
    VERIFY(m_lock.is_locked());

    VERIFY(!Processor::current_in_irq());

    int attempts = 0;
    u8 response;
    do {
        if (device != HIDDevice::Type::Keyboard) {
            prepare_for_output();
            IO::out8(I8042Port::Command, I8042Command::WriteSecondPS2PortInputBuffer);
        }
        prepare_for_output();
        IO::out8(I8042Port::Buffer, data);

        response = do_wait_then_read(I8042Port::Buffer);
    } while (response == I8042Response::Resend && ++attempts < 3);
    if (attempts >= 3)
        dbgln("Failed to write byte to device, gave up");
    return response;
}

u8 I8042Controller::do_read_from_device(HIDDevice::Type device)
{
    VERIFY(device != HIDDevice::Type::Unknown);

    prepare_for_input(device);
    return IO::in8(I8042Port::Buffer);
}

void I8042Controller::prepare_for_input(HIDDevice::Type device)
{
    VERIFY(m_lock.is_locked());
    u8 const second_port_flag = device == HIDDevice::Type::Keyboard ? 0 : I8042StatusFlag::SecondPS2PortOutputBuffer;
    for (;;) {
        u8 status = IO::in8(I8042Port::Status);
        if (!(status & I8042StatusFlag::OutputBuffer))
            continue;
        if (device == HIDDevice::Type::Unknown)
            return;
        if ((status & I8042StatusFlag::SecondPS2PortOutputBuffer) == second_port_flag)
            return;
    }
}

void I8042Controller::prepare_for_output()
{
    VERIFY(m_lock.is_locked());
    for (;;) {
        u8 status = IO::in8(I8042Port::Status);
        if (!(status & I8042StatusFlag::InputBuffer))
            return;
    }
}

void I8042Controller::do_wait_then_write(u8 port, u8 data)
{
    VERIFY(m_lock.is_locked());
    prepare_for_output();
    IO::out8(port, data);
}

u8 I8042Controller::do_wait_then_read(u8 port)
{
    VERIFY(m_lock.is_locked());
    prepare_for_input(HIDDevice::Type::Unknown);
    return IO::in8(port);
}

}