STRUCT SPI_MASTER(9) Serial Peripheral Interface (S STRUCT SPI_MASTER(9)NAMEstruct_spi_master - interface to SPI master controller
SYNOPSIS
struct spi_master {
struct device dev;
s16 bus_num;
u16 num_chipselect;
u16 dma_alignment;
u16 mode_bits;
u16 flags;
#define SPI_MASTER_HALF_DUPLEX BIT(0)
#define SPI_MASTER_NO_RX BIT(1)
#define SPI_MASTER_NO_TX BIT(2)
int (* setup) (struct spi_device *spi);
int (* transfer) (struct spi_device *spi,struct spi_message *mesg);
void (* cleanup) (struct spi_device *spi);
};
MEMBERS
dev
device interface to this driver
bus_num
board-specific (and often SOC-specific) identifier for a given SPI
controller.
num_chipselect
chipselects are used to distinguish individual SPI slaves, and are
numbered from zero to num_chipselects. each slave has a chipselect
signal, but it´s common that not every chipselect is connected to a
slave.
dma_alignment
SPI controller constraint on DMA buffers alignment.
mode_bits
flags understood by this controller driver
flags
other constraints relevant to this driver
setup
updates the device mode and clocking records used by a device´s SPI
controller; protocol code may call this. This must fail if an
unrecognized or unsupported mode is requested. It´s always safe to
call this unless transfers are pending on the device whose settings
are being modified.
transfer
adds a message to the controller´s transfer queue.
cleanup
frees controller-specific state
DESCRIPTION
Each SPI master controller can communicate with one or more spi_device
children. These make a small bus, sharing MOSI, MISO and SCK signals
but not chip select signals. Each device may be configured to use a
different clock rate, since those shared signals are ignored unless the
chip is selected.
The driver for an SPI controller manages access to those devices
through a queue of spi_message transactions, copying data between CPU
memory and an SPI slave device. For each such message it queues, it
calls the message´s completion function when the transaction completes.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 STRUCT SPI_MASTER(9)
