centos man page for spi_alloc_master

SPI_ALLOC_MASTER(9)					  Serial Peripheral Interface (S				       SPI_ALLOC_MASTER(9)

NAME
       spi_alloc_master - allocate SPI master controller

SYNOPSIS
       struct spi_master * spi_alloc_master(struct device * dev, unsigned size);

ARGUMENTS
       dev
	   the controller, possibly using the platform_bus

       size
	   how much zeroed driver-private data to allocate; the pointer to this memory is in the driver_data field of the returned device,
	   accessible with spi_master_get_devdata.

CONTEXT
       can sleep

DESCRIPTION
       This call is used only by SPI master controller drivers, which are the only ones directly touching chip registers. It's how they allocate
       an spi_master structure, prior to calling spi_register_master.

       This must be called from context that can sleep. It returns the SPI master structure on success, else NULL.

       The caller is responsible for assigning the bus number and initializing the master's methods before calling spi_register_master; and (after
       errors adding the device) calling spi_master_put and kfree to prevent a memory leak.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						       SPI_ALLOC_MASTER(9)