NAME

       s390_pci_mmio_write, s390_pci_mmio_read - transfer data to/from PCI MMIO memory page

SYNOPSIS

       #include <asm/unistd.h>

       int s390_pci_mmio_write(unsigned long mmio_addr,
                               void *user_buffer, size_t length);
       int s390_pci_mmio_read(unsigned long mmio_addr,
                               void *user_buffer, size_t length);

DESCRIPTION

       The  s390_pci_mmio_write() system call writes length bytes of data from the user-space buffer user_buffer
       to the PCI MMIO memory location specified by  mmio_addr.   The  s390_pci_mmio_read()  system  call  reads
       length  bytes  of  data from the PCI MMIO memory location specified by mmio_addr to the user-space buffer
       user_buffer.

       These system calls must be used instead of the simple assignment or  data-transfer  operations  that  are
       used  to  access  the  PCI  MMIO  memory  areas mapped to user space on the Linux System z platform.  The
       address specified by mmio_addr must belong to a PCI MMIO memory page  mapping  in  the  caller's  address
       space,  and  the  data  being written or read must not cross a page boundary.  The length value cannot be
       greater than the system page size.

RETURN VALUE

       On success, s390_pci_mmio_write() and s390_pci_mmio_read() return 0.  On error, -1 is returned and  errno
       is set to one of the error codes listed below.

ERRORS

       EFAULT The address in mmio_addr is invalid.

       EFAULT user_buffer does not point to a valid location in the caller's address space.

       EINVAL Invalid length argument.

       ENODEV PCI support is not enabled.

       ENOMEM Insufficient memory.

VERSIONS

       These system calls are available since Linux 3.19.

CONFORMING TO

       This  Linux-specific system call is available only on the s390 architecture.  The required PCI support is
       available beginning with System z EC12.

NOTES

       Glibc does not provide a wrapper for this system call, use syscall(2) to call it.

SEE ALSO

       syscall(2)

COLOPHON

       This page is part of release 4.04 of  the  Linux  man-pages  project.   A  description  of  the  project,
       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.

Linux Programmer's Manual                          2015-01-15                             S390_PCI_MMIO_WRITE(2)