centos man page for spi_bus_lock

SPI_BUS_LOCK(9) 					  Serial Peripheral Interface (S					   SPI_BUS_LOCK(9)

NAME
       spi_bus_lock - obtain a lock for exclusive SPI bus usage

SYNOPSIS
       int spi_bus_lock(struct spi_master * master);

ARGUMENTS
       master
	   SPI bus master that should be locked for exclusive bus access

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.

       This call should be used by drivers that require exclusive access to the SPI bus. The SPI bus must be released by a spi_bus_unlock call
       when the exclusive access is over. Data transfer must be done by spi_sync_locked and spi_async_locked calls when the SPI bus lock is held.

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

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							   SPI_BUS_LOCK(9)