s390_pci_mmio_write (2) Linux Manual Page
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.