spi_write_then_read9
Spi synchronous write followed by read
Usage
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
Overview
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.
Releases
5 releases since Debian 4.0 (Etch); the text changed 4 times.