NAME

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

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

       int syscall(SYS_s390_pci_mmio_write, unsigned long mmio_addr,
                              const void user_buffer[.length], size_t length);
       int syscall(SYS_s390_pci_mmio_read, unsigned long mmio_addr,
                              void user_buffer[.length], size_t length);

       Note: glibc provides no wrappers for these system calls, necessitating the use of syscall(2).

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  failure,  -1  is  returned  and
       errno is set to indicate the error.

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.

STANDARDS

       Linux on s390.

HISTORY

       Linux 3.19.  System z EC12.

SEE ALSO

       syscall(2)