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 4.15 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 https://www.kernel.org/doc/man-pages/.