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.

VERSIONS¶

These system calls are available since Linux 3.19.

STANDARDS¶

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

SEE ALSO¶

syscall(2)