Linux SPI User-Space API

RTEMS port of Linux SPI user-space API. More...

Files
file	spidev.h
	RTEMS Port of Linux SPI API.

Data Structures
struct	spi_ioc_transfer
	SPI transfer message. More...

Macros
#define	SPI_IOC_MAGIC   's'
#define	SPI_MSGSIZE(n)
	Calculates the size of the SPI message array. More...
#define	SPI_IOC_MESSAGE(n)   _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(n)])
	Transfers an array with SPI messages.
#define	SPI_IOC_RD_MODE   _IOR(SPI_IOC_MAGIC, 1, uint8_t)
	Reads the least-significant 8-bits of the SPI default mode.
#define	SPI_IOC_WR_MODE   _IOW(SPI_IOC_MAGIC, 1, uint8_t)
	Writes the SPI default mode (the most-significant 24-bits of the mode are set to zero).
#define	SPI_IOC_RD_LSB_FIRST   _IOR(SPI_IOC_MAGIC, 2, uint8_t)
	Reads the SPI default least-significant bit first setting.
#define	SPI_IOC_WR_LSB_FIRST   _IOW(SPI_IOC_MAGIC, 2, uint8_t)
	Writes the SPI default least-significant-bit first setting.
#define	SPI_IOC_RD_BITS_PER_WORD   _IOR(SPI_IOC_MAGIC, 3, uint8_t)
	Reads the SPI default bits per word.
#define	SPI_IOC_WR_BITS_PER_WORD   _IOW(SPI_IOC_MAGIC, 3, uint8_t)
	Writes the SPI default bits per word.
#define	SPI_IOC_RD_MAX_SPEED_HZ   _IOR(SPI_IOC_MAGIC, 4, uint32_t)
	Reads the SPI default speed in Hz.
#define	SPI_IOC_WR_MAX_SPEED_HZ   _IOW(SPI_IOC_MAGIC, 4, uint32_t)
	Writes the SPI default speed in Hz.
#define	SPI_IOC_RD_MODE32   _IOR(SPI_IOC_MAGIC, 5, uint32_t)
	Reads the full 32-bit SPI default mode.
#define	SPI_IOC_WR_MODE32   _IOW(SPI_IOC_MAGIC, 5, uint32_t)
	Writes the full 32-bit SPI default mode.

Variables
void *	spi_ioc_transfer::rx_buf
	Buffer for receive data.
const void *	spi_ioc_transfer::tx_buf
	Buffer for transmit data.
size_t	spi_ioc_transfer::len
	Length of receive and transmit buffers in bytes.
uint32_t	spi_ioc_transfer::speed_hz
	Sets the bit-rate of the device.
uint16_t	spi_ioc_transfer::delay_usecs
	Sets the delay after a transfer before the chip select status is changed and the next transfer is triggered.
uint8_t	spi_ioc_transfer::bits_per_word
	Sets the device wordsize.
uint8_t	spi_ioc_transfer::cs_change
	If true, device is deselected after transfer ended and before a new transfer is started.
uint8_t	spi_ioc_transfer::rx_nbits
	Amount of bits that are used for reading.
uint8_t	spi_ioc_transfer::tx_nbits
	Amount of bits that are used for writing.
uint32_t	spi_ioc_transfer::mode
	Sets one of the possible modes that can be used for SPI transfers (dependent on clock phase and polarity).
uint8_t	spi_ioc_transfer::cs
	Indicates which device is currently used.

SPI Transfer Flags
#define	SPI_CPHA   0x01
	SPI transfer flag which sets the clock phase.
#define	SPI_CPOL   0x02
	SPI transfer flag which sets the clock polarity.
#define	SPI_MODE_0   0
	SPI transfer flag which sets SPI Mode 0 (clock starts low, sample on leading edge).
#define	SPI_MODE_1   SPI_CPHA
	SPI transfer flag which sets SPI Mode 0 (clock starts low, sample on trailing edge).
#define	SPI_MODE_2   SPI_CPOL
	SPI transfer flag which sets SPI Mode 0 (clock starts high, sample on leading edge).
#define	SPI_MODE_3   (SPI_CPOL | SPI_CPHA)
	SPI transfer flag which sets SPI Mode 0 (clock starts high, sample on trailing edge).
#define	SPI_CS_HIGH   0x04
	SPI transfer flag which selects the device by setting the chip select line.
#define	SPI_LSB_FIRST   0x08
	SPI transfer flag which triggers data transmission with the LSB being sent first.
#define	SPI_3WIRE   0x10
	SPI transfer flag which uses a shared wire for master input/slave output as well as master output/slave input.
#define	SPI_LOOP   0x20
	SPI transfer flag which initiates the loopback mode.
#define	SPI_NO_CS   0x40
	SPI transfer flag which indicates that no chip select is needed due to only one device on the bus.
#define	SPI_READY   0x80
	SPI transfer flag which pulls the slave to low level during pause.
#define	SPI_TX_DUAL   0x100
	SPI transfer flag which sets up dual mode for transmission.
#define	SPI_TX_QUAD   0x200
	SPI transfer flag which sets up quad mode for transmission.
#define	SPI_RX_DUAL   0x400
	SPI transfer flag which sets up dual mode for reception.
#define	SPI_RX_QUAD   0x800
	SPI transfer flag which sets up quad mode for reception.

Detailed Description

RTEMS port of Linux SPI user-space API.

Additional documentation is available through the Linux sources, see

/usr/src/linux/include/uapi/linux/spidev.h.

Macro Definition Documentation

SPI_MSGSIZE

#define SPI_MSGSIZE

(

n

)

Value:

(((n) * sizeof(struct spi_ioc_transfer) < IOCPARM_MAX) ? \
    (n) * sizeof(struct spi_ioc_transfer) : 0)

Calculates the size of the SPI message array.