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vba_badaddr(9r)
NAME
  vba_badaddr - VMEbus: Determines whether a VMEbus device is present

SYNOPSIS
  int vba_badaddr(
	  struct controller *ctlr,
	  io_handle_t ioh,
	  vme_atype_t flags,
	  int len );

ARGUMENTS
  ctlr
      Specifies a pointer to the VMEbus device's controller data structure.

  ioh Specifies the I/O handle for the device being probed.  The I/O handle
      must have a valid byte alignment that corresponds to the size specified
      in the len parameter.

  atype
      A bit-encoded argument that specifies the address space, transfer size,
      access mode, and swap mode for the address to be probed.	This argument
      should match the atype argument previously specified for the I/O handle
      in a vba_map_csr() call or driver structure.

  len Specifies the size (in bytes) of the data transfer to be performed to
      the VMEbus address. Values of 1, 2, 4, and 8 result in byte, word,
      longword, and quadword transfers, respectively.  If the I/O handle was
      mapped with the VME_DENSE flag set, you may only specify 4 or 8.

DESCRIPTION
  The vba_badaddr() routine probes a VMEbus address to determine whether the
  associated VMEbus device is present.

  This routine is called from a VMEbus device driver's probe() routine.	 If
  the vba_badaddr() return indicates that the device is not present, the
  driver probe() routine returns a failure status to the bus configuration
  interface.

RETURN VALUES
  The vba_badaddr() routine returns 0 (zero) if the VMEbus device is present
  or a nonzero value if the device is not present.








EXAMPLE
  The following code fragment shows a call to the vba_badaddr() routine from
  the probe() routine of VMEbus example device driver:

       .
       .
       .

       if (vba_badaddr(ctlr,
		       sc->csr_handle + DMAEX_CSR_OFF,
		       ctlr->driver->addr1_atype,
		       DMAEX_CSR_SIZE))
	 return(0);

       .
       .
       .


  The driver example chapter of Writing VMEbus Device Drivers shows how the
  dmaex example driver calls vba_badaddr() to probe the VMEbus device.	See
  the section in the driver example chapter that explains the dmaex_probe()
  routine.

SEE ALSO
  Kernel Routines: probe(9r), vba_map_csr(9r)

  Data Structures: driver(9s)

Index for Section 9

Alphabetical listing for V

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