serialstream.cxx

C++ 编写的EROS RTOS

/*
 * Copyright (C) 2001, Jonathan S. Shapiro.
 *
 * This file is part of the EROS Operating System.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/* This is a serial debugging stream based closely on the earlier
 * logic introduced by Mike Hilsdale. */

#include <kerninc/kernel.hxx>
#include <kerninc/KernStream.hxx>
#include <kerninc/IRQ.hxx>
#include <eros/i486/io.h>
#include <eros/i486/fixregs.h>
#include "IDT.hxx"

/* This class has a singleton instance! */
struct SerialStream: public KernStream {
  void Init();
  void Put(uint8_t c);

#ifdef OPTION_DDB
  uint8_t Get();
  void SetDebugging(bool onoff);
  void EnableDebuggerInput();
#endif
};

#define COMIRQ   IRQ386::Serial0
#define COMBASE  0x3f8

struct SerialStream TheSerialStream;
KernStream* KernStream::SerialStream = &TheSerialStream;

void
SerialStream::Init()
{
  uint16_t dlab = COMBASE + 3;

  /* Initialize COM port */

  /* Currently: 9600, 8N1 */
  /* (This seemes to not be needed when using VMware
   * and psuedo terminal pipes, but it's here for
   * completeness and for real hardware.)
   */

  /* set DLAB bit      */
  /* b7=1              */
  old_outb(dlab, inb(dlab) ^ 0x80);

  /* set 16-bit divisor to 12 (0Ch = 9600 baud) */
  old_outb(COMBASE, 0x0C);
  old_outb(COMBASE + 1, 0);

  /* set data bits to 8 */
  /* b0=1 b1=1          */
  old_outb(dlab, inb(dlab) ^ 0x03);

  /* set parity to None */
  /* b3=0 b4=4 b5=0     */
  old_outb(dlab, inb(dlab) & 0xC7);

  /* set stop bits to 1 */
  /* b2=0               */
  old_outb(dlab, inb(dlab) & 0xFB);

  /* unset DLAB bit     */
  /* b7=0               */
  old_outb(COMBASE + 3, inb(COMBASE + 3) & 0x70);

  /* tell COM port to report INTs on received char */
  old_outb(COMBASE + 1, 1);
}

uint8_t
SerialStream::Get()
{
  uint8_t c;

  /* This is incorrect: Should be spinning waiting for a valid
   * character! */
  c = inb(COMBASE);

  return c;
}

void
SerialStream::Put(uint8_t c)
{
  /* This *may* be incorrect. Should *probably* be spinning waiting
   * for room in the output fifo! */
  old_outb(COMBASE, c);

  return;
}


void
SerialStream::SetDebugging(bool onOff)
{
  debuggerIsActive = onOff;
  
  if (debuggerIsActive == false)
    IRQ::Enable(COMIRQ);
}

static void
SerialInterrupt(fixregs_t *sa)
{
  char c;
  uint32_t irq = IRQ_FROM_EXCEPTION(sa->ExceptNo);

  /* look at interrupt id to quell UART */
  /* may want to actually do something here sometime later */
  inb(COMBASE + 2);

  if (KernStream::debuggerIsActive)
    return;

  assert(irq == COMIRQ);

  c = TheSerialStream.Get();

  if (c == ASCII::ETX)
    Debugger();

  IRQ::Enable(irq);
}

void
SerialStream::EnableDebuggerInput()
{
  IRQ::SetHandler(COMIRQ, SerialInterrupt);
  printf("Set up keyboard (console) interrupt handler!\n");

#if 0
  /* Establish initial keyboard state visibly: */
  UpdateKbdLeds();
#endif

  /* FIX: This may prove a problem, as I need to check exactly where
   * the interrupt vectors are set up in the boot sequence... */
  IRQ::Enable(COMIRQ);
}