mirror of https://github.com/mkerrisk/man-pages
110 lines
3.2 KiB
Groff
110 lines
3.2 KiB
Groff
.\" Copyright (c) IBM Corp. 2015
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.\" Author: Alexey Ishchuk <aishchuk@linux.vnet.ibm.com>
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, see
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.\" <http://www.gnu.org/licenses/>.
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.\" %%%LICENSE_END
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.\"
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.TH S390_PCI_MMIO_WRITE 2 2021-03-22 "Linux Programmer's Manual"
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.SH NAME
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s390_pci_mmio_write, s390_pci_mmio_read \- transfer data to/from PCI
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MMIO memory page
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.SH SYNOPSIS
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.nf
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.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
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.B #include <unistd.h>
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.PP
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.BI "int syscall(SYS_s390_pci_mmio_write, unsigned long " mmio_addr ,
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.BI " const void *" user_buffer ", size_t " length );
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.BI "int syscall(SYS_s390_pci_mmio_read, unsigned long " mmio_addr ,
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.BI " void *" user_buffer ", size_t " length );
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.fi
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.PP
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.IR Note :
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glibc provides no wrappers for these system calls,
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necessitating the use of
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.BR syscall (2).
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.SH DESCRIPTION
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The
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.BR s390_pci_mmio_write ()
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system call writes
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.IR length
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bytes of data from the user-space buffer
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.IR user_buffer
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to the PCI MMIO memory location specified by
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.IR mmio_addr .
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The
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.BR s390_pci_mmio_read ()
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system call reads
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.I length
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bytes of
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data from the PCI MMIO memory location specified by
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.IR mmio_addr
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to the user-space buffer
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.IR user_buffer .
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.PP
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These system calls must be used instead of the simple assignment
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or data-transfer operations that are used to access the PCI MMIO
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memory areas mapped to user space on the Linux System z platform.
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The address specified by
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.IR mmio_addr
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must belong to a PCI MMIO memory page mapping in the caller's address space,
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and the data being written or read must not cross a page boundary.
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The
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.IR length
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value cannot be greater than the system page size.
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.SH RETURN VALUE
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On success,
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.BR s390_pci_mmio_write ()
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and
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.BR s390_pci_mmio_read ()
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return 0.
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On failure, \-1 is returned and
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.IR errno
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is set to indicate the error.
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.SH ERRORS
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.TP
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.B EFAULT
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The address in
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.I mmio_addr
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is invalid.
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.TP
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.B EFAULT
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.IR user_buffer
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does not point to a valid location in the caller's address space.
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.TP
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.B EINVAL
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Invalid
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.I length
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argument.
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.TP
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.B ENODEV
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PCI support is not enabled.
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.TP
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.B ENOMEM
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Insufficient memory.
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.SH VERSIONS
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These system calls are available since Linux 3.19.
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.SH CONFORMING TO
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This Linux-specific system call is available only on the s390 architecture.
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The required PCI support is available beginning with System z EC12.
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.SH SEE ALSO
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.BR syscall (2)
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