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https://github.com/RGBCube/serenity
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1b2ef8582c
Asking a File if we could possibly read or write it will never mutate the asking FileDescription&, so it should be const.
110 lines
2.6 KiB
C++
110 lines
2.6 KiB
C++
#include <Kernel/Devices/SerialDevice.h>
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#include <Kernel/IO.h>
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SerialDevice::SerialDevice(int base_addr, unsigned minor)
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: CharacterDevice(4, minor)
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, m_base_addr(base_addr)
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{
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initialize();
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}
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SerialDevice::~SerialDevice()
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{
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}
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bool SerialDevice::can_read(const FileDescription&) const
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{
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return (get_line_status() & DataReady) != 0;
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}
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ssize_t SerialDevice::read(FileDescription&, u8* buffer, ssize_t size)
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{
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if (!size)
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return 0;
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if (!(get_line_status() & DataReady))
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return 0;
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buffer[0] = IO::in8(m_base_addr);
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return 1;
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}
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bool SerialDevice::can_write(const FileDescription&) const
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{
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return (get_line_status() & EmptyTransmitterHoldingRegister) != 0;
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}
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ssize_t SerialDevice::write(FileDescription&, const u8* buffer, ssize_t size)
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{
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if (!size)
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return 0;
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if (!(get_line_status() & EmptyTransmitterHoldingRegister))
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return 0;
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IO::out8(m_base_addr, buffer[0]);
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return 1;
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}
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void SerialDevice::initialize()
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{
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set_interrupts(0);
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set_baud(Baud38400);
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set_line_control(None, One, EightBits);
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set_fifo_control(EnableFIFO | ClearReceiveFIFO | ClearTransmitFIFO | TriggerLevel4);
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set_modem_control(RequestToSend | DataTerminalReady);
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}
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void SerialDevice::set_interrupts(char interrupt_enable)
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{
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m_interrupt_enable = interrupt_enable;
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IO::out8(m_base_addr + 1, interrupt_enable);
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}
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void SerialDevice::set_baud(Baud baud)
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{
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m_baud = baud;
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IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) | 0x80); // turn on DLAB
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IO::out8(m_base_addr + 0, ((char)(baud)) >> 2); // lower half of divisor
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IO::out8(m_base_addr + 1, ((char)(baud)) & 0xff); // upper half of divisor
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IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & 0x7f); // turn off DLAB
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}
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void SerialDevice::set_fifo_control(char fifo_control)
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{
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m_fifo_control = fifo_control;
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IO::out8(m_base_addr + 2, fifo_control);
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}
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void SerialDevice::set_line_control(ParitySelect parity_select, StopBits stop_bits, WordLength word_length)
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{
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m_parity_select = parity_select;
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m_stop_bits = stop_bits;
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m_word_length = word_length;
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IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (0xc0 | parity_select | stop_bits | word_length));
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}
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void SerialDevice::set_break_enable(bool break_enable)
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{
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m_break_enable = break_enable;
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IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (break_enable ? 0xff : 0xbf));
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}
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void SerialDevice::set_modem_control(char modem_control)
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{
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m_modem_control = modem_control;
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IO::out8(m_base_addr + 4, modem_control);
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}
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char SerialDevice::get_line_status() const
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{
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return IO::in8(m_base_addr + 5);
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}
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