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probe(9r)
NAME
  probe - VMEbus: Determines whether the device exists

SYNOPSIS
  int probe(
	  io_handle_t addr1,
	  struct controller *ctlr );

ARGUMENTS
  addr1
      Specifies an I/O handle that you can use to reference a device register
      located in the VMEbus address space. The VMEbus configuration code
      passes this I/O handle to the driver's probe() routine during device
      autoconfiguration.  You can perform standard C mathematical operations
      (addition and subtraction only) on the I/O handle. For example, you can
      add an offset to or subtract an offset from the I/O handle.

      This I/O handle corresponds to the first control and status register
      (CSR) address that you specified in a VBA_Option entry in the
      /etc/sysconfigtab file.  (The data structures chapter of Writing VMEbus
      Device Drivers describes the VBA_Option entry.) You use the Csr1 field
      of the VBA_Option	 entry to specify the CSR address for the VMEbus
      device, as follows:
	   VBA_Option = ..., Csr1 - 0x8020, ...

      The bus configuration code converts the Csr1 address, combined with
      information in driver data structure members addr1_size and
      addr1_atype, into an appropriate I/O handle and passes it to the
      driver's probe() routine.

  ctlr
      Specifies a pointer to the VMEbus device's controller data structure.
      The bus configuration code passes this pointer to the driver's probe()
      routine.	The device driver can reference hardware resources and other
      information contained in the controller data structure pointer.

      If a second CSR was specified in a VBA_Option entry in the
      /etc/sysconfigtab file, the VMEbus configuration code passes
      information in the addr2 member of the controller data structure
      pointer.	This member contains an I/O handle that you can use to
      reference a device register located in the VMEbus onboard memory.	 You
      can perform standard C mathematical operations (addition and
      subtraction only) on the I/O handle. For example, you can add an offset
      to or subtract an offset from the I/O handle.

      You can use the Csr2 field of the VBA_Option entry to specify an
      optional second VMEbus device register or memory address to map into
      CPU I/O space, as follows:
	   VBA_Option = ..., Csr2 - 0x8040, ...

      The bus configuration code converts the Csr2 address, combined with
      information in driver data structure members addr2_size and
      addr2_atype, into an appropriate I/O handle.  It is not passed to the
      driver's probe() routine, but is available in the driver's controller
      data structure.


ENTRY POINT
  The driver data structure

DESCRIPTION
  A device driver's probe() routine performs tasks necessary to determine if
  the device exists and is functional on a given system.  At boot time, the
  kernel performs checks to determine if the device is present before calling
  the probe() routine for statically configured drivers. For dynamically
  configured drivers, the probe() routine is called indirectly during the
  driver loading process.

  The driver's configure() routine calls the configure_driver() routine to
  merge the driver's connectivity information into the system (hardware)
  configuration tree, which consists of bus, controller, and device data
  structures. The call to configure_driver() results in the system calling
  probe() for each instance of the controller present on the VMEbus.

  The probe() routine typically checks some device control and status
  register (CSR) to determine whether the physical device is present. If the
  device is not present, the device is not initialized and is not available
  for use.

  In previous versions of the operating system, you defined the device
  interrupt handlers for static device drivers in the system configuration
  file or in a stanza.static file fragment. At system configuration time, the
  config program registered the defined device interrupt handlers. Beginning
  with Version 4.0 of the operating system, you are required to register the
  device interrupt handlers for static device drivers in the same way that
  you register them for loadable device drivers: by calling the handler_add()
  and handler_enable() routines.

  The arguments you pass to the probe() routine differ according to the bus
  on which the driver operates. The SYNOPSIS section shows the arguments
  associated with a probe() routine for a VMEbus.

NOTES
  Device drivers pass the I/O handle to the following categories of routines,
  which are discussed in Writing Device Drivers.  These routines can process
  the I/O handle to access the desired bus address space.

    ·  CSR I/O access routines

       The CSR I/O access routines are read_io_port() and write_io_port().
       These are generic routines that allow device drivers to read from and
       write to device registers. Using these routines to read data from and
       write data to a device register makes the device driver more portable
       across different bus architectures, different CPU architectures, and
       different CPU types within the same CPU architecture.

    ·  I/O copy routines

       The I/O copy routines are io_copyin(), io_copyio(), io_copyout(), and
       io_zero().  These are generic routines that allow device drivers to
       perform I/O copy operations. Using these routines to perform the copy
       operation makes the device driver more portable across different CPU
       architectures and different CPU types within the same architecture.







RETURN VALUES
  The probe() routine returns a nonzero value if the probe operation is
  successful. It returns the value 0 (zero) to indicate that the driver did
  not complete the probe operation.

SEE ALSO
  Kernel Routines: slave(9r)

Index for Section 9

Alphabetical listing for P

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