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SPI_WRITE_THEN_READ(9) Serial Peripheral Interface (S SPI_WRITE_THEN_READ(9)

NAME

spi_write_then_read - SPI synchronous write followed by read

SYNOPSIS

int spi_write_then_read(struct spi_device * spi, const void * txbuf, unsigned n_tx, void * rxbuf, unsigned n_rx);

ARGUMENTS

spi
device with which data will be exchanged
txbuf
data to be written (need not be dma-safe)
n_tx
size of txbuf, in bytes
rxbuf
buffer into which data will be read (need not be dma-safe)
n_rx
size of rxbuf, in bytes

CONTEXT

can sleep

DESCRIPTION

This performs a half duplex MicroWire style transaction with the device, sending txbuf and then reading rxbuf. The return value is zero for success, else a negative errno status code. This call may only be used from a context that may sleep.
Parameters to this routine are always copied using a small buffer; portable code should never use this for more than 32 bytes. Performance-sensitive or bulk transfer code should instead use spi_{async,sync}() calls with dma-safe buffers.

COPYRIGHT

March 2016 Kernel Hackers Manual 3.2.