s390_pci_mmio_read(2)

1s390_pci_mmio_write(2)        System Calls Manual       s390_pci_mmio_write(2)
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NAME

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

10       Standard C library (libc, -lc)
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SYNOPSIS

13       #include <sys/syscall.h>      /* Definition of SYS_* constants */
14       #include <unistd.h>
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16       int syscall(SYS_s390_pci_mmio_write, unsigned long mmio_addr,
17                              const void user_buffer[.length], size_t length);
18       int syscall(SYS_s390_pci_mmio_read, unsigned long mmio_addr,
19                              void user_buffer[.length], size_t length);
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21       Note: glibc provides no wrappers for these system calls,  necessitating
22       the use of syscall(2).
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DESCRIPTION

25       The  s390_pci_mmio_write() system call writes length bytes of data from
26       the user-space buffer user_buffer to the PCI MMIO memory location spec‐
27       ified  by mmio_addr.  The s390_pci_mmio_read() system call reads length
28       bytes of data from the PCI MMIO memory location specified by  mmio_addr
29       to the user-space buffer user_buffer.
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31       These  system  calls  must  be used instead of the simple assignment or
32       data-transfer operations that are used to access the  PCI  MMIO  memory
33       areas mapped to user space on the Linux System z platform.  The address
34       specified by mmio_addr must belong to a PCI MMIO memory page mapping in
35       the caller's address space, and the data being written or read must not
36       cross a page boundary.  The length value cannot  be  greater  than  the
37       system page size.
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RETURN VALUE

40       On  success,  s390_pci_mmio_write()  and s390_pci_mmio_read() return 0.
41       On failure, -1 is returned and errno is set to indicate the error.
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ERRORS

44       EFAULT The address in mmio_addr is invalid.
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46       EFAULT user_buffer does not point to a valid location in  the  caller's
47              address space.
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49       EINVAL Invalid length argument.
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51       ENODEV PCI support is not enabled.
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53       ENOMEM Insufficient memory.
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STANDARDS

56       Linux on s390.
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HISTORY

59       Linux 3.19.  System z EC12.
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