spi_read(9) [centos man page]

SPI_READ(9)						  Serial Peripheral Interface (S					       SPI_READ(9)

NAME

       spi_read - SPI synchronous read

SYNOPSIS

       int spi_read(struct spi_device * spi, void * buf, size_t len);

ARGUMENTS

       spi
	   device from which data will be read

       buf
	   data buffer

       len
	   data buffer size

CONTEXT

       can sleep

DESCRIPTION

       This reads the buffer and returns zero or a negative error code. Callable only from contexts that can sleep.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							       SPI_READ(9)

SPI_ASYNC_LOCKED(9)					  Serial Peripheral Interface (S				       SPI_ASYNC_LOCKED(9)

NAME

       spi_async_locked - version of spi_async with exclusive bus usage

SYNOPSIS

       int spi_async_locked(struct spi_device * spi, struct spi_message * message);

ARGUMENTS

       spi
	   device with which data will be exchanged

       message
	   describes the data transfers, including completion callback

CONTEXT

       any (irqs may be blocked, etc)

DESCRIPTION

       This call may be used in_irq and other contexts which can't sleep, as well as from task contexts which can sleep.

       The completion callback is invoked in a context which can't sleep. Before that invocation, the value of message->status is undefined. When
       the callback is issued, message->status holds either zero (to indicate complete success) or a negative error code. After that callback
       returns, the driver which issued the transfer request may deallocate the associated memory; it's no longer in use by any SPI core or
       controller driver code.

       Note that although all messages to a spi_device are handled in FIFO order, messages may go to different devices in other orders. Some
       device might be higher priority, or have various "hard" access time requirements, for example.

       On detection of any fault during the transfer, processing of the entire message is aborted, and the device is deselected. Until returning
       from the associated message completion callback, no other spi_message queued to that device will be processed. (This rule applies equally
       to all the synchronous transfer calls, which are wrappers around this core asynchronous primitive.)

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						       SPI_ASYNC_LOCKED(9)