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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 information.

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.

IOCTLS

The following ioctl(2) calls apply to SPI devices. They are defined in the header file <dev/spi/spi_io.h>:

SPI_IOCTL_CONFIGURE (spi_ioctl_configure_t)

Used to choose the operational mode and clock. The sic_mode defines polarity and phase of the clock. sic_speed is the clock speed in Hz, a value of 0 means to keep the default speed of the device.

typedef struct spi_ioctl_configure {
	int sic_addr;
	int sic_mode;
	int sic_speed;
} spi_ioctl_configure_t;

SPI_IOCTL_TRANSFER (spi_ioctl_transfer_t)

Used to handle an I/O transaction.

typedef struct spi_ioctl_transfer {
	int sit_addr;
	const void *sit_send;
	size_t sit_sendlen;
	void *sit_recv;
	size_t sit_recvlen;
} spi_ioctl_transfer_t;

HARDWARE

NetBSD includes the following machine-independent SPI drivers:

FILES

/dev/spiu

SPI device unit u file.

SEE ALSO

m25p(4), mcp23s17gpio(4), mcp3kadc(4), mcp48x1dac(4), ssdfb(4), tm121temp(4), spi(9)

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. The ioctl(2) interface allowing configuration from userspace appeared in NetBSD 9.0.