From 8b1154f5f24fe775aaa23c85bec676c5d0131b91 Mon Sep 17 00:00:00 2001 From: Conrad Pankoff Date: Sat, 8 Jun 2019 23:24:34 +1000 Subject: [PATCH] Kernel: Implement serial port driver This implements a basic 8250 UART serial port driver. It does not currently handle (or enable) interrupts, nor any runtime configuration. --- Kernel/Devices/SerialDevice.cpp | 110 +++++++++++++++++++++++++++++ Kernel/Devices/SerialDevice.h | 120 ++++++++++++++++++++++++++++++++ Kernel/Makefile | 1 + Kernel/build-root-filesystem.sh | 4 ++ Kernel/init.cpp | 9 +++ 5 files changed, 244 insertions(+) create mode 100644 Kernel/Devices/SerialDevice.cpp create mode 100644 Kernel/Devices/SerialDevice.h diff --git a/Kernel/Devices/SerialDevice.cpp b/Kernel/Devices/SerialDevice.cpp new file mode 100644 index 0000000000..d945e4c1d4 --- /dev/null +++ b/Kernel/Devices/SerialDevice.cpp @@ -0,0 +1,110 @@ +#include +#include + +SerialDevice::SerialDevice(int base_addr, unsigned minor) + : CharacterDevice(4, minor) + , m_base_addr(base_addr) +{ + initialize(); +} + +SerialDevice::~SerialDevice() +{ +} + +bool SerialDevice::can_read(FileDescription&) const +{ + return (get_line_status() & DataReady) != 0; +} + +ssize_t SerialDevice::read(FileDescription&, byte* buffer, ssize_t size) +{ + if (!size) + return 0; + + if (!(get_line_status() & DataReady)) + return 0; + + buffer[0] = IO::in8(m_base_addr); + + return 1; +} + +bool SerialDevice::can_write(FileDescription&) const +{ + return (get_line_status() & EmptyTransmitterHoldingRegister) != 0; +} + +ssize_t SerialDevice::write(FileDescription&, const byte* buffer, ssize_t size) +{ + if (!size) + return 0; + + if (!(get_line_status() & EmptyTransmitterHoldingRegister)) + return 0; + + IO::out8(m_base_addr, buffer[0]); + + return 1; +} + +void SerialDevice::initialize() +{ + set_interrupts(0); + set_baud(Baud38400); + set_line_control(None, One, EightBits); + set_fifo_control(EnableFIFO | ClearReceiveFIFO | ClearTransmitFIFO | TriggerLevel4); + set_modem_control(RequestToSend | DataTerminalReady); +} + +void SerialDevice::set_interrupts(char interrupt_enable) +{ + m_interrupt_enable = interrupt_enable; + + IO::out8(m_base_addr + 1, interrupt_enable); +} + +void SerialDevice::set_baud(Baud baud) +{ + m_baud = baud; + + IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) | 0x80); // turn on DLAB + IO::out8(m_base_addr + 0, ((char)(baud)) >> 2); // lower half of divisor + IO::out8(m_base_addr + 1, ((char)(baud)) & 0xff); // upper half of divisor + IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & 0x7f); // turn off DLAB +} + +void SerialDevice::set_fifo_control(char fifo_control) +{ + m_fifo_control = fifo_control; + + IO::out8(m_base_addr + 2, fifo_control); +} + +void SerialDevice::set_line_control(ParitySelect parity_select, StopBits stop_bits, WordLength word_length) +{ + m_parity_select = parity_select; + m_stop_bits = stop_bits; + m_word_length = word_length; + + IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (0xc0 | parity_select | stop_bits | word_length)); +} + +void SerialDevice::set_break_enable(bool break_enable) +{ + m_break_enable = break_enable; + + IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (break_enable ? 0xff : 0xbf)); +} + +void SerialDevice::set_modem_control(char modem_control) +{ + m_modem_control = modem_control; + + IO::out8(m_base_addr + 4, modem_control); +} + +char SerialDevice::get_line_status() const +{ + return IO::in8(m_base_addr + 5); +} diff --git a/Kernel/Devices/SerialDevice.h b/Kernel/Devices/SerialDevice.h new file mode 100644 index 0000000000..3cccf0c91a --- /dev/null +++ b/Kernel/Devices/SerialDevice.h @@ -0,0 +1,120 @@ +#include + +#define SERIAL_COM1_ADDR 0x3F8 +#define SERIAL_COM2_ADDR 0x2F8 +#define SERIAL_COM3_ADDR 0x3E8 +#define SERIAL_COM4_ADDR 0x2E8 + +class SerialDevice final : public CharacterDevice { + AK_MAKE_ETERNAL +public: + SerialDevice(int base_addr, unsigned minor); + virtual ~SerialDevice() override; + + // ^CharacterDevice + virtual bool can_read(FileDescription&) const override; + virtual ssize_t read(FileDescription&, byte*, ssize_t) override; + virtual bool can_write(FileDescription&) const override; + virtual ssize_t write(FileDescription&, const byte*, ssize_t) override; + + enum InterruptEnable { + LowPowerMode = 0x01 << 5, + SleepMode = 0x01 << 4, + ModemStatusInterrupt = 0x01 << 3, + ReceiverLineStatusInterrupt = 0x01 << 2, + TransmitterHoldingRegisterEmptyInterrupt = 0x01 << 1, + ReceivedDataAvailableInterrupt = 0x01 << 0 + }; + + enum Baud { + Baud50 = 2304, + Baud110 = 1047, + Baud220 = 524, + Baud300 = 384, + Baud600 = 192, + Baud1200 = 96, + Baud2400 = 48, + Baud4800 = 24, + Baud9600 = 12, + Baud19200 = 6, + Baud38400 = 3, + Baud57600 = 2, + Baud115200 = 1 + }; + + enum ParitySelect { + None = 0x00 << 3, + Odd = 0x01 << 3, + Even = 0x03 << 3, + Mark = 0x05 << 3, + Space = 0x07 << 3 + }; + + enum StopBits { + One = 0x00 << 2, + Two = 0x01 << 2 + }; + + enum WordLength { + FiveBits = 0x00, + SixBits = 0x01, + SevenBits = 0x02, + EightBits = 0x03 + }; + + enum FIFOControl { + EnableFIFO = 0x01 << 0, + ClearReceiveFIFO = 0x01 << 1, + ClearTransmitFIFO = 0x01 << 2, + Enable64ByteFIFO = 0x01 << 5, + TriggerLevel1 = 0x00 << 6, + TriggerLevel2 = 0x01 << 6, + TriggerLevel3 = 0x02 << 6, + TriggerLevel4 = 0x03 << 6 + }; + + enum ModemControl { + AutoflowControlEnabled = 0x01 << 5, + LoopbackMode = 0x01 << 4, + AuxiliaryOutput2 = 0x01 << 3, + AuxiliaryOutput1 = 0x01 << 2, + RequestToSend = 0x01 << 1, + DataTerminalReady = 0x01 << 0 + }; + + enum LineStatus { + ErrorInReceivedFIFO = 0x01 << 7, + EmptyDataHoldingRegisters = 0x01 << 6, + EmptyTransmitterHoldingRegister = 0x01 << 5, + BreakInterrupt = 0x01 << 4, + FramingError = 0x01 << 3, + ParityError = 0x01 << 2, + OverrunError = 0x01 << 1, + DataReady = 0x01 << 0 + }; + +private: + // ^CharacterDevice + virtual const char* class_name() const override { return "SerialDevice"; } + + void initialize(); + void set_interrupts(char interrupt_enable); + void set_baud(Baud); + void set_fifo_control(char fifo_control); + void set_line_control(ParitySelect, StopBits, WordLength); + void set_break_enable(bool break_enable); + void set_modem_control(char modem_control); + char get_line_status() const; + bool rx_ready(); + bool tx_ready(); + + int m_base_addr; + char m_interrupt_enable; + char m_fifo_control; + Baud m_baud; + ParitySelect m_parity_select; + StopBits m_stop_bits; + WordLength m_word_length; + bool m_break_enable; + char m_modem_control; +}; diff --git a/Kernel/Makefile b/Kernel/Makefile index 07a1501129..cd5d3a5b75 100644 --- a/Kernel/Makefile +++ b/Kernel/Makefile @@ -38,6 +38,7 @@ KERNEL_OBJS = \ Devices/BXVGADevice.o \ PCI.o \ Devices/PS2MouseDevice.o \ + Devices/SerialDevice.o \ Net/Socket.o \ Net/LocalSocket.o \ Net/IPv4Socket.o \ diff --git a/Kernel/build-root-filesystem.sh b/Kernel/build-root-filesystem.sh index 3a7af24044..2e2870b9d3 100755 --- a/Kernel/build-root-filesystem.sh +++ b/Kernel/build-root-filesystem.sh @@ -24,6 +24,10 @@ mknod mnt/dev/tty0 c 4 0 mknod mnt/dev/tty1 c 4 1 mknod mnt/dev/tty2 c 4 2 mknod mnt/dev/tty3 c 4 3 +mknod mnt/dev/ttyS0 c 4 64 +mknod mnt/dev/ttyS1 c 4 65 +mknod mnt/dev/ttyS2 c 4 66 +mknod mnt/dev/ttyS3 c 4 67 mknod mnt/dev/random c 1 8 mknod mnt/dev/null c 1 3 mknod mnt/dev/zero c 1 5 diff --git a/Kernel/init.cpp b/Kernel/init.cpp index 429f7a8456..cde76f94e2 100644 --- a/Kernel/init.cpp +++ b/Kernel/init.cpp @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -40,6 +41,10 @@ KeyboardDevice* keyboard; PS2MouseDevice* ps2mouse; DebugLogDevice* dev_debuglog; NullDevice* dev_null; +SerialDevice* ttyS0; +SerialDevice* ttyS1; +SerialDevice* ttyS2; +SerialDevice* ttyS3; VFS* vfs; #ifdef STRESS_TEST_SPAWNING @@ -173,6 +178,10 @@ extern "C" [[noreturn]] void init() keyboard = new KeyboardDevice; ps2mouse = new PS2MouseDevice; dev_null = new NullDevice; + ttyS0 = new SerialDevice(SERIAL_COM1_ADDR, 64); + ttyS1 = new SerialDevice(SERIAL_COM2_ADDR, 65); + ttyS2 = new SerialDevice(SERIAL_COM3_ADDR, 66); + ttyS3 = new SerialDevice(SERIAL_COM4_ADDR, 67); VirtualConsole::initialize(); tty0 = new VirtualConsole(0, VirtualConsole::AdoptCurrentVGABuffer);