spi(4) [netbsd man page]

SPI(4)							   BSD Kernel Interfaces Manual 						    SPI(4)

NAME

     spi -- introduction to machine-independent SPI bus support and drivers

SYNOPSIS

     spi* at mainbus?

     Other attachments are machine-dependent and will depend on the bus topology of your system.  See intro(4) for your system for more informa-
     tion.

DESCRIPTION

     NetBSD includes a machine dependent SPI (Serial Peripheral Interface) bus subsystem, and several different machine-independent SPI device
     drivers.

     Your system may support additional machine-dependent SPI devices.	Consult your system's intro(4) for additional information.

     SPI is a 4-wire synchronous full-duplex serial bus.  Some systems provide support for Microwire, which is Philips' name for a strict subset
     of SPI, with more rigidly defined signaling.  Therefore, Microwire devices are also supported by the SPI framework.

     Note that when referencing SPI devices in a config(1) file, the 'slave' must be provided, as SPI lacks any way to automatically probe
     devices.

HARDWARE

     NetBSD includes the following machine-independent SPI drivers

	   m25p       STMicroelectronics M25P family of NOR flash devices.

	   tm121temp  Texas Instruments TMP121 temperature sensor.

SEE ALSO

     m25p(4), tm121temp(4)

HISTORY

     The machine-independent SPI framework was written by Garrett D'Amore for the Champaign-Urbana Community Wireless Network Project (CUWiN), and
     appeared in NetBSD 4.0.

BSD
								  October 9, 2006							       BSD

STRUCT 
SPI_MASTER(9)					  Serial Peripheral Interface (S				      STRUCT SPI_MASTER(9)

NAME

       struct_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.

COPYRIGHT

Kernel Hackers Manual 2.6.					     July 2010						      STRUCT SPI_MASTER(9)