spi_w8r8(9) centos man page | unix.com

SPI_W8R8(9)						  Serial Peripheral Interface (S					       SPI_W8R8(9)

NAME
       spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read

SYNOPSIS
       ssize_t spi_w8r8(struct spi_device * spi, u8 cmd);

ARGUMENTS
       spi
	   device with which data will be exchanged

       cmd
	   command to be written before data is read back

CONTEXT
       can sleep

DESCRIPTION
       This returns the (unsigned) eight bit number returned by the device, or else a negative error code. Callable only from contexts that can
       sleep.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							       SPI_W8R8(9)