centos man page for spi_sync_locked

SPI_SYNC_LOCKED(9)					  Serial Peripheral Interface (S					SPI_SYNC_LOCKED(9)

NAME
       spi_sync_locked - version of spi_sync with exclusive bus usage

SYNOPSIS
       int spi_sync_locked(struct spi_device * spi, struct spi_message * message);

ARGUMENTS
       spi
	   device with which data will be exchanged

       message
	   describes the data transfers

CONTEXT
       can sleep

DESCRIPTION
       This call may only be used from a context that may sleep. The sleep is non-interruptible, and has no timeout. Low-overhead controller
       drivers may DMA directly into and out of the message buffers.

       This call should be used by drivers that require exclusive access to the SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus
       must be released by a spi_bus_unlock call when the exclusive access is over.

       It returns zero on success, else a negative error code.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							SPI_SYNC_LOCKED(9)