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io_copyin(9r)
NAME
  io_copyin - General: Copies data from bus address space to system memory

SYNOPSIS
  int io_copyin(
	  io_handle_t srcaddr,
	  vm_offset_t destaddr,
	  u_long byte_count );

ARGUMENTS
  srcaddr
      Specifies an I/O handle that you can use to reference a device register
      or memory located in bus address space (either I/O space or memory
      space). For io_copyin, the I/O handle identifies the location in bus
      address space where the copy originates. 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.

  destaddr
      Specifies the kernel virtual address where io_copyin copies the data to
      in-system memory.

  byte_count
      Specifies the number of bytes in the data block to be copied.  The
      interface assumes that the buffer associated with the data block is
      physically contiguous.

DESCRIPTION
  The io_copyin interface copies data from bus address space to system
  memory. The interface optimizes the copy operation for 32-bit transfers.
  The I/O handle you pass to srcaddr identifies where the copy originates in
  bus address space, and the address you pass to destaddr identifies where
  the copy occurs in system memory. The io_copyin interface assumes no
  alignment of data associated with srcaddr and destaddr.

NOTES
  The io_copyin interface is a generic interface that maps to a bus- and
  machine-specific interface that actually performs the copy from bus address
  space to system memory. Using io_copyin to perform the copy operation makes
  the device driver more portable across different CPU architectures and
  different CPU types within the same architecture.







CAUTIONS
  The I/O handle that you pass to the srcaddr argument of the io_copyin
  interface must be an I/O handle that references addresses residing in
  sparse space. All Alpha CPUs support sparse space.  As a result, all bus
  configuration code should supply an I/O handle that references bus address
  space.

  If you pass an I/O handle to the srcaddr argument that references addresses
  residing in some other space (for example, dense space) the results of the
  copy operation are unpredictable.

  Tru64 UNIX provides the following interfaces that allow device drivers to
  perform copy operations and zero blocks of memory on addresses that reside
  in dense space:

    ·  bcopy

       Copies a series of bytes with a specified limit

    ·  blkclr and bzero

       Zeros a block of memory

    ·  copyin

       Copies data from a user address space to a kernel address space

    ·  copyinstr

       Copies a null-terminated string from a user address space to a kernel
       address space

    ·  copyout

       Copies data from a kernel address space to a user address space

    ·  copyoutstr

       Copies a null-terminated string from a kernel address space to a user
       address space

RETURN VALUES
  Upon successful completion, io_copyin returns IOA_OKAY. It returns the
  value -1 on failure.

EXAMPLE
  See Writing Device Drivers: Tutorial for a code example of the io_copyin
  interface.

SEE ALSO
  Kernel Interfaces: io_copyio(9r), io_copyout(9r)

Index for Section 9

Alphabetical listing for I

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