man2/s390_pci_mmio_write.2

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   2 .\" Author: Alexey Ishchuk <aishchuk@linux.vnet.ibm.com>
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  25 .TH S390_PCI_MMIO_WRITE 2 2017-09-15 "Linux Programmer's Manual"
  26 .SH NAME
  27 s390_pci_mmio_write, s390_pci_mmio_read \- transfer data to/from PCI
  28 MMIO memory page
  29 .SH SYNOPSIS
  30 .nf
  31 .B #include <asm/unistd.h>
  32 .PP
  33 .BI "int s390_pci_mmio_write(unsigned long " mmio_addr ",
  34 .BI "                        void *" user_buffer ", size_t " length ");
  35 .BI "int s390_pci_mmio_read(unsigned long " mmio_addr ",
  36 .BI "                        void *" user_buffer ", size_t " length ");
  37 .fi
  38 .SH DESCRIPTION
  39 The
  40 .BR s390_pci_mmio_write ()
  41 system call writes
  42 .IR length
  43 bytes of data from the user-space buffer
  44 .IR user_buffer
  45 to the PCI MMIO memory location specified by
  46 .IR mmio_addr .
  47 The
  48 .BR s390_pci_mmio_read ()
  49 system call reads
  50 .I length
  51 bytes of
  52 data from the PCI MMIO memory location specified by
  53 .IR mmio_addr
  54 to the user-space buffer
  55 .IR user_buffer .
  56 .PP
  57 These system calls must be used instead of the simple assignment
  58 or data-transfer operations that are used to access the PCI MMIO
  59 memory areas mapped to user space on the Linux System z platform.
  60 The address specified by
  61 .IR mmio_addr
  62 must belong to a PCI MMIO memory page mapping in the caller's address space,
  63 and the data being written or read must not cross a page boundary.
  64 The
  65 .IR length
  66 value cannot be greater than the system page size.
  67 .SH RETURN VALUE
  68 On success,
  69 .BR s390_pci_mmio_write ()
  70 and
  71 .BR s390_pci_mmio_read ()
  72 return 0.
  73 On error, \-1 is returned and
  74 .IR errno
  75 is set to one of the error codes listed below.
  76 .SH ERRORS
  77 .TP
  78 .B EFAULT
  79 The address in
  80 .I mmio_addr
  81 is invalid.
  82 .TP
  83 .B EFAULT
  84 .IR user_buffer
  85 does not point to a valid location in the caller's address space.
  86 .TP
  87 .B EINVAL
  88 Invalid
  89 .I length
  90 argument.
  91 .TP
  92 .B ENODEV
  93 PCI support is not enabled.
  94 .TP
  95 .B ENOMEM
  96 Insufficient memory.
  97 .SH VERSIONS
  98 These system calls are available since Linux 3.19.
  99 .SH CONFORMING TO
 100 This Linux-specific system call is available only on the s390 architecture.
 101 The required PCI support is available beginning with System z EC12.
 102 .SH NOTES
 103 Glibc does not provide a wrapper for this system call, use
 104 .BR syscall (2)
 105 to call it.
 106 .SH SEE ALSO
 107 .BR syscall (2)