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Niklas Gollenstede
196
kernel/arch/serial.h
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196
kernel/arch/serial.h
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/*! \file
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* \brief Communication via the \ref Serial interface (RS-232)
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*/
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#pragma once
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#include "../types.h"
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/*! \brief Serial interface.
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* \ingroup io
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*
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* This class provides a serial interface (COM1 - COM4) for communication with
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* the outside world.
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*
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* The first IBM PC used the external chip [8250
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* UART](https://de.wikipedia.org/wiki/NSC_8250), whereas, in today's systems,
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* this functionality is commonly integrated into the motherboard chipset, but
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* remained compatible.
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*
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* \see [PC8250A Data Sheet](uart-8250a.pdf#page=11) (Registers on page 11)
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* \see [PC16550D Data Sheet](uart-16550d.pdf#page=16) (Successor, for optional
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* FIFO buffer, page 16)
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*/
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class Serial {
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public:
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/*! \brief COM-Port
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*
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* The serial interface and its hardware addresses. Modern desktop PCs
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* have, at most, a single, physical COM-port (`COM1`)
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*/
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enum class ComPort : uint16_t {
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COM1 = 0x3f8,
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COM2 = 0x2f8,
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COM3 = 0x3e8,
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COM4 = 0x2e8,
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};
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/*! \brief Transmission speed
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*
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* The unit Baud describes the transmission speed in number of symbols per
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* seconds. 1 Baud therefore equals the transmission of 1 symbol per second.
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* The possible Baud rates are whole-number dividers of the clock frequency
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* of 115200 Hz..
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*/
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enum class BaudRate : uint16_t {
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B300 = 384,
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B600 = 192,
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B1200 = 96,
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B2400 = 48,
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B4800 = 24,
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B9600 = 12,
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B19200 = 6,
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B38400 = 3,
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B57600 = 2,
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B115200 = 1,
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};
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/*! \brief Number of data bits per character */
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enum class DataBits : uint8_t {
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D5 = 0,
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D6 = 1,
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D7 = 2,
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D8 = 3,
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};
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/*! \brief Number of stop bits per character */
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enum class StopBits : uint8_t {
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S1 = 0,
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S1_5 = 4,
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S2 = 4,
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};
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/*! \brief parity bit */
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enum class Parity : uint8_t {
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NONE = 0,
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ODD = 8,
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EVEN = 24,
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MARK = 40,
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SPACE = 56,
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};
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private:
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/*! \brief register index */
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enum class RegisterIndex : uint8_t {
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RECEIVE_BUFFER = 0,
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TRANSMIT_BUFFER = 0,
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INTERRUPT_ENABLE = 1,
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DIVISOR_LOW = 0,
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DIVISOR_HIGH = 1,
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INTERRUPT_IDENT = 2,
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FIFO_CONTROL = 2,
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LINE_CONTROL = 3,
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MODEM_CONTROL = 4,
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LINE_STATUS = 5,
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MODEM_STATUS = 6
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};
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/*! \brief Mask for the respective register */
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enum class RegisterMask : uint8_t {
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RECEIVED_DATA_AVAILABLE = 1 << 0,
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TRANSMITTER_HOLDING_REGISTER_EMPTY = 1 << 1,
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RECEIVER_LINE_STATUS = 1 << 2,
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MODEM_STATUS = 1 << 3,
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// Interrupt Ident Register
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INTERRUPT_PENDING = 1 << 0, ///< 0 means interrupt pending
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INTERRUPT_ID_0 = 1 << 1,
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INTERRUPT_ID_1 = 1 << 2,
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// FIFO Control Register
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ENABLE_FIFO = 1 << 0, ///< 0 means disabled ^= conforming to 8250a
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CLEAR_RECEIVE_FIFO = 1 << 1,
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CLEAR_TRANSMIT_FIFO = 1 << 2,
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DMA_MODE_SELECT = 1 << 3,
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TRIGGER_RECEIVE = 1 << 6,
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// Line Control Register
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// bits per character: 5 6 7 8
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WORD_LENGTH_SELECT_0 = 1 << 0, // Setting Select0: 0 1 0 1
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WORD_LENGTH_SELECT_1 = 1 << 1, // Setting Select1: 0 0 1 1
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NUMBER_OF_STOP_BITS = 1 << 2, // 0 ≙ one stop bit, 1 ≙ 1.5/2 stop bits
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PARITY_ENABLE = 1 << 3,
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EVEN_PARITY_SELECT = 1 << 4,
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STICK_PARITY = 1 << 5,
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SET_BREAK = 1 << 6,
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DIVISOR_LATCH_ACCESS_BIT = 1 << 7, // DLAB
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// Modem Control Register
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DATA_TERMINAL_READY = 1 << 0,
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REQUEST_TO_SEND = 1 << 1,
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OUT_1 = 1 << 2,
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OUT_2 = 1 << 3, // must be set for interrupts!
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LOOP = 1 << 4,
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// Line Status Register
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DATA_READY = 1 << 0, // Set when there is a value in the receive buffer
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OVERRUN_ERROR = 1 << 1,
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PARITY_ERROR = 1 << 2,
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FRAMING_ERROR = 1 << 3,
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BREAK_INTERRUPT = 1 << 4,
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TRANSMITTER_HOLDING_REGISTER = 1 << 5,
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TRANSMITTER_EMPTY = 1 << 6, // Send buffer empty (ready to send)
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// Modem Status Register
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DELTA_CLEAR_TO_SEND = 1 << 0,
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DELTA_DATA_SET_READY = 1 << 1,
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TRAILING_EDGE_RING_INDICATOR = 1 << 2,
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DELTA_DATA_CARRIER_DETECT = 1 << 3,
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CLEAR_TO_SEND = 1 << 4,
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DATA_SET_READY = 1 << 5,
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RING_INDICATOR = 1 << 6,
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DATA_CARRIER_DETECT = 1 << 7
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};
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/*! \brief Read value from register
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*
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*
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* \param reg Register index
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* \return The value read from register
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*/
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uint8_t readReg(RegisterIndex reg);
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/*! \brief Write value to register
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*
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*
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* \param reg Register index
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* \param out value to be written
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*/
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void writeReg(RegisterIndex reg, uint8_t out);
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protected:
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/*! \brief Selected COM port */
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const ComPort port;
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public:
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/*! \brief Constructor
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*
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* Creates a Serial object that encapsulates the used COM port, as well as
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* the parameters used for the serial connection. Default values are `8N1`
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* (8 bit, no parity bit, one stop bit) with 115200 Baud using COM1.
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*
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*/
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explicit Serial(ComPort port = ComPort::COM1,
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BaudRate baud_rate = BaudRate::B115200,
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DataBits data_bits = DataBits::D8,
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StopBits stop_bits = StopBits::S1,
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Parity parity = Parity::NONE);
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/*! \brief Write one byte to the serial interface
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*
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*
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* \param out Byte to be written
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* \return Byte written (or `-1` if writing byte failed)
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*/
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int write(uint8_t out);
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};
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