struct spi_device
Prev | Chapter 26. Serial Peripheral Interface (SPI) | Next

## Name

struct spi_device — Master side proxy for an SPI slave device

## Synopsis

    struct spi_device {
      struct device dev;
      struct spi_master * master;
      u32 max_speed_hz;
      u8 chip_select;
      u8 mode;
    #define SPI_CPHA	0x01
    #define SPI_CPOL	0x02
    #define SPI_MODE_0	(0|0)
    #define SPI_MODE_1	(0|SPI_CPHA)
    #define SPI_MODE_2	(SPI_CPOL|0)
    #define SPI_MODE_3	(SPI_CPOL|SPI_CPHA)
    #define SPI_CS_HIGH	0x04
    #define SPI_LSB_FIRST	0x08
    #define SPI_3WIRE	0x10
    #define SPI_LOOP	0x20
      u8 bits_per_word;
      int irq;
      void * controller_state;
      void * controller_data;
      const char * modalias;
    };

## Members

dev

  Driver model representation of the device.

master

  SPI controller used with the device.

max_speed_hz

  Maximum clock rate to be used with this chip (on this board); may be changed by the device's driver. The spi_transfer.speed_hz can override this for each transfer.

chip_select

  Chipselect, distinguishing chips handled by `master`.

mode

  The spi mode defines how data is clocked out and in. This may be changed by the device's driver. The “active low” default for chipselect mode can be overridden (by specifying SPI_CS_HIGH) as can the “MSB first” default for each word in a transfer (by specifying SPI_LSB_FIRST).

bits_per_word

  Data transfers involve one or more words; word sizes like eight or 12 bits are common. In-memory wordsizes are powers of two bytes (e.g. 20 bit samples use 32 bits). This may be changed by the device's driver, or left at the default (0) indicating protocol words are eight bit bytes. The spi_transfer.bits_per_word can override this for each transfer.

irq

  Negative, or the number passed to `request_irq` to receive interrupts from this device.

controller_state

  Controller's runtime state

controller_data

  Board-specific definitions for controller, such as FIFO initialization parameters; from board_info.controller_data

modalias

  Name of the driver to use with this device, or an alias for that name. This appears in the sysfs “modalias” attribute for driver coldplugging, and in uevents used for hotplugging

## Description

A `spi_device` is used to interchange data between an SPI slave (usually a discrete chip) and CPU memory.

In `dev`, the platform_data is used to hold information about this device that's meaningful to the device's protocol driver, but not to its controller. One example might be an identifier for a chip variant with slightly different functionality; another might be information about how this particular board wires the chip's pins.

Prev | Up | Next
Chapter 26. Serial Peripheral Interface (SPI) | Home | struct spi_driver