floppy.c

minix3.1.1源代码

 * opcode.  This routine sets up the DMA chip.  Note that the chip is not
 * capable of doing a DMA across a 64K boundary (e.g., you can't read a
 * 512-byte block starting at physical address 65520).
 *
 * Warning! Also note that it's not possible to do DMA above 16 MB because 
 * the ISA bus uses 24-bit addresses. Addresses above 16 MB therefore will 
 * be interpreted modulo 16 MB, dangerously overwriting arbitrary memory. 
 * A check here denies the I/O if the address is out of range. 
 */
  pvb_pair_t byte_out[9];
  int s;

  /* First check the DMA memory address not to exceed maximum. */
  if (tmp_phys != (tmp_phys & DMA_ADDR_MASK)) {
	report("FLOPPY", "DMA denied because address out of range", NO_NUM);
	return(EIO);
  }

  /* Set up the DMA registers.  (The comment on the reset is a bit strong,
   * it probably only resets the floppy channel.)
   */
  pv_set(byte_out[0], DMA_INIT, DMA_RESET_VAL);	/* reset the dma controller */
  pv_set(byte_out[1], DMA_FLIPFLOP, 0);		/* write anything to reset it */
  pv_set(byte_out[2], DMA_MODE, opcode == DEV_SCATTER ? DMA_WRITE : DMA_READ);
  pv_set(byte_out[3], DMA_ADDR, (unsigned) tmp_phys >>  0);
  pv_set(byte_out[4], DMA_ADDR, (unsigned) tmp_phys >>  8);
  pv_set(byte_out[5], DMA_TOP, (unsigned) (tmp_phys >> 16));
  pv_set(byte_out[6], DMA_COUNT, (((SECTOR_SIZE - 1) >> 0) & 0xff));
  pv_set(byte_out[7], DMA_COUNT, (SECTOR_SIZE - 1) >> 8);
  pv_set(byte_out[8], DMA_INIT, 2);		/* some sort of enable */

  if ((s=sys_voutb(byte_out, 9)) != OK)
  	panic("FLOPPY","Sys_voutb in dma_setup() failed", s);
  return(OK);
}

/*===========================================================================*
 *				start_motor				     *
 *===========================================================================*/
PRIVATE void start_motor()
{
/* Control of the floppy disk motors is a big pain.  If a motor is off, you
 * have to turn it on first, which takes 1/2 second.  You can't leave it on
 * all the time, since that would wear out the diskette.  However, if you turn
 * the motor off after each operation, the system performance will be awful.
 * The compromise used here is to leave it on for a few seconds after each
 * operation.  If a new operation is started in that interval, it need not be
 * turned on again.  If no new operation is started, a timer goes off and the
 * motor is turned off.  I/O port DOR has bits to control each of 4 drives.
 */

  int s, motor_bit, running;
  message mess;

  motor_bit = 1 << f_drive;		/* bit mask for this drive */
  running = motor_status & motor_bit;	/* nonzero if this motor is running */
  motor_status |= motor_bit;		/* want this drive running too */

  if ((s=sys_outb(DOR,
  		(motor_status << MOTOR_SHIFT) | ENABLE_INT | f_drive)) != OK)
	panic("FLOPPY","Sys_outb in start_motor() failed", s);

  /* If the motor was already running, we don't have to wait for it. */
  if (running) return;			/* motor was already running */

  /* Set an alarm timer to force a timeout if the hardware does not interrupt
   * in time. Expect HARD_INT message, but check for SYN_ALARM timeout.
   */ 
  f_set_timer(&f_tmr_timeout, f_dp->start, f_timeout);
  f_busy = BSY_IO;
  do {
  	receive(ANY, &mess); 
  	if (mess.m_type == SYN_ALARM) { 
  		f_expire_tmrs(NULL, NULL);
	} else if(mess.m_type == DEV_PING) {
		notify(mess.m_source);
  	} else {
  		f_busy = BSY_IDLE;
  	}
  } while (f_busy == BSY_IO);
  f_fp->fl_sector = NO_SECTOR;
}

/*===========================================================================*
 *				stop_motor				     *
 *===========================================================================*/
PRIVATE void stop_motor(tp)
timer_t *tp;
{
/* This routine is called from an alarm timer after several seconds have
 * elapsed with no floppy disk activity.  It turns the drive motor off.
 */
  int s;
  motor_status &= ~(1 << tmr_arg(tp)->ta_int);
  if ((s=sys_outb(DOR, (motor_status << MOTOR_SHIFT) | ENABLE_INT)) != OK)
	panic("FLOPPY","Sys_outb in stop_motor() failed", s);
}

/*===========================================================================*
 *				floppy_stop				     *
 *===========================================================================*/
PRIVATE void floppy_stop(struct driver *dp, message *m_ptr)
{
/* Stop all activity and cleanly exit with the system. */
  int s;
  sigset_t sigset = m_ptr->NOTIFY_ARG;
  if (sigismember(&sigset, SIGTERM) || sigismember(&sigset, SIGKSTOP)) {
      if ((s=sys_outb(DOR, ENABLE_INT)) != OK)
		panic("FLOPPY","Sys_outb in floppy_stop() failed", s);
      exit(0);	
  }
}

/*===========================================================================*
 *				seek					     *
 *===========================================================================*/
PRIVATE int seek()
{
/* Issue a SEEK command on the indicated drive unless the arm is already
 * positioned on the correct cylinder.
 */

  struct floppy *fp = f_fp;
  int r;
  message mess;
  u8_t cmd[3];

  /* Are we already on the correct cylinder? */
  if (fp->fl_calibration == UNCALIBRATED)
	if (recalibrate() != OK) return(ERR_SEEK);
  if (fp->fl_curcyl == fp->fl_hardcyl) return(OK);

  /* No.  Wrong cylinder.  Issue a SEEK and wait for interrupt. */
  cmd[0] = FDC_SEEK;
  cmd[1] = (fp->fl_head << 2) | f_drive;
  cmd[2] = fp->fl_hardcyl;
  if (fdc_command(cmd, 3) != OK) return(ERR_SEEK);
  if (f_intr_wait() != OK) return(ERR_TIMEOUT);

  /* Interrupt has been received.  Check drive status. */
  fdc_out(FDC_SENSE);		/* probe FDC to make it return status */
  r = fdc_results();		/* get controller status bytes */
  if (r != OK || (f_results[ST0] & ST0_BITS_SEEK) != SEEK_ST0
				|| f_results[ST1] != fp->fl_hardcyl) {
	/* seek failed, may need a recalibrate */
	return(ERR_SEEK);
  }
  /* Give head time to settle on a format, no retrying here! */
  if (f_device & FORMAT_DEV_BIT) {
	/* Set a synchronous alarm to force a timeout if the hardware does
	 * not interrupt. Expect HARD_INT, but check for SYN_ALARM timeout.
 	 */ 
 	f_set_timer(&f_tmr_timeout, HZ/30, f_timeout);
	f_busy = BSY_IO;
  	do {
  		receive(ANY, &mess); 
  		if (mess.m_type == SYN_ALARM) { 
  			f_expire_tmrs(NULL, NULL);
		} else if(mess.m_type == DEV_PING) {
			notify(mess.m_source);
  		} else {
  			f_busy = BSY_IDLE;
  		}
  	} while (f_busy == BSY_IO);
  }
  fp->fl_curcyl = fp->fl_hardcyl;
  fp->fl_sector = NO_SECTOR;
  return(OK);
}

/*===========================================================================*
 *				fdc_transfer				     *
 *===========================================================================*/
PRIVATE int fdc_transfer(opcode)
int opcode;			/* DEV_GATHER or DEV_SCATTER */
{
/* The drive is now on the proper cylinder.  Read, write or format 1 block. */

  struct floppy *fp = f_fp;
  int r, s;
  u8_t cmd[9];

  /* Never attempt a transfer if the drive is uncalibrated or motor is off. */
  if (fp->fl_calibration == UNCALIBRATED) return(ERR_TRANSFER);
  if ((motor_status & (1 << f_drive)) == 0) return(ERR_TRANSFER);

  /* The command is issued by outputting several bytes to the controller chip.
   */
  if (f_device & FORMAT_DEV_BIT) {
	cmd[0] = FDC_FORMAT;
	cmd[1] = (fp->fl_head << 2) | f_drive;
	cmd[2] = fmt_param.sector_size_code;
	cmd[3] = fmt_param.sectors_per_cylinder;
	cmd[4] = fmt_param.gap_length_for_format;
	cmd[5] = fmt_param.fill_byte_for_format;
	if (fdc_command(cmd, 6) != OK) return(ERR_TRANSFER);
  } else {
	cmd[0] = opcode == DEV_SCATTER ? FDC_WRITE : FDC_READ;
	cmd[1] = (fp->fl_head << 2) | f_drive;
	cmd[2] = fp->fl_cylinder;
	cmd[3] = fp->fl_head;
	cmd[4] = BASE_SECTOR + fp->fl_sector;
	cmd[5] = SECTOR_SIZE_CODE;
	cmd[6] = f_sectors;
	cmd[7] = f_dp->gap;	/* sector gap */
	cmd[8] = DTL;		/* data length */
	if (fdc_command(cmd, 9) != OK) return(ERR_TRANSFER);
  }

  /* Block, waiting for disk interrupt. */
  if (f_intr_wait() != OK) {
	printf("%s: disk interrupt timed out.\n", f_name());
  	return(ERR_TIMEOUT);
  }

  /* Get controller status and check for errors. */
  r = fdc_results();
  if (r != OK) return(r);

  if (f_results[ST1] & WRITE_PROTECT) {
	printf("%s: diskette is write protected.\n", f_name());
	return(ERR_WR_PROTECT);
  }

  if ((f_results[ST0] & ST0_BITS_TRANS) != TRANS_ST0) return(ERR_TRANSFER);
  if (f_results[ST1] | f_results[ST2]) return(ERR_TRANSFER);

  if (f_device & FORMAT_DEV_BIT) return(OK);

  /* Compare actual numbers of sectors transferred with expected number. */
  s =  (f_results[ST_CYL] - fp->fl_cylinder) * NR_HEADS * f_sectors;
  s += (f_results[ST_HEAD] - fp->fl_head) * f_sectors;
  s += (f_results[ST_SEC] - BASE_SECTOR - fp->fl_sector);
  if (s != 1) return(ERR_TRANSFER);

  /* This sector is next for I/O: */
  fp->fl_sector = f_results[ST_SEC] - BASE_SECTOR;
#if 0
  if (processor < 386) fp->fl_sector++;		/* Old CPU can't keep up. */
#endif
  return(OK);
}

/*===========================================================================*
 *				fdc_results				     *
 *===========================================================================*/
PRIVATE int fdc_results()
{
/* Extract results from the controller after an operation, then allow floppy
 * interrupts again.
 */

  int s, result_nr, status;
  clock_t t0,t1;

  /* Extract bytes from FDC until it says it has no more.  The loop is
   * really an outer loop on result_nr and an inner loop on status. 
   * A timeout flag alarm is set.
   */
  result_nr = 0;
  getuptime(&t0);
  do {
	/* Reading one byte is almost a mirror of fdc_out() - the DIRECTION
	 * bit must be set instead of clear, but the CTL_BUSY bit destroys
	 * the perfection of the mirror.
	 */
	if ((s=sys_inb(FDC_STATUS, &status)) != OK)
		panic("FLOPPY","Sys_inb in fdc_results() failed", s);
	status &= (MASTER | DIRECTION | CTL_BUSY);
	if (status == (MASTER | DIRECTION | CTL_BUSY)) {
		if (result_nr >= MAX_RESULTS) break;	/* too many results */
		if ((s=sys_inb(FDC_DATA, &f_results[result_nr])) != OK)
		   panic("FLOPPY","Sys_inb in fdc_results() failed", s);
		result_nr ++;
		continue;
	}
	if (status == MASTER) {			/* all read */
		if ((s=sys_irqenable(&irq_hook_id)) != OK)
			panic("FLOPPY", "Couldn't enable IRQs", s);

		return(OK);			/* only good exit */
	}
  } while ( (s=getuptime(&t1))==OK && (t1-t0) < TIMEOUT_TICKS );
  if (OK!=s) printf("FLOPPY: warning, getuptime failed: %d\n", s); 
  need_reset = TRUE;		/* controller chip must be reset */

  if ((s=sys_irqenable(&irq_hook_id)) != OK)
	panic("FLOPPY", "Couldn't enable IRQs", s);
  return(ERR_STATUS);
}

/*===========================================================================*
 *				fdc_command				     *
 *===========================================================================*/
PRIVATE int fdc_command(cmd, len)
u8_t *cmd;		/* command bytes */
int len;		/* command length */
{
/* Output a command to the controller. */

  /* Set a synchronous alarm to force a timeout if the hardware does
   * not interrupt. Expect HARD_INT, but check for SYN_ALARM timeout.
   * Note that the actual check is done by the code that issued the
   * fdc_command() call.
   */ 
  f_set_timer(&f_tmr_timeout, WAKEUP, f_timeout);

  f_busy = BSY_IO;
  while (len > 0) {
	fdc_out(*cmd++);
	len--;
  }
  return(need_reset ? ERR_DRIVE : OK);
}

/*===========================================================================*
 *				fdc_out					     *
 *===========================================================================*/
PRIVATE void fdc_out(val)
int val;		/* write this byte to floppy disk controller */
{
/* Output a byte to the controller.  This is not entirely trivial, since you
 * can only write to it when it is listening, and it decides when to listen.