struct spi_board_info — board-specific template for a SPI device
struct spi_board_info {
char modalias[SPI_NAME_SIZE];
const void * platform_data;
void * controller_data;
int irq;
u32 max_speed_hz;
u16 bus_num;
u16 chip_select;
u16 mode;
}; Initializes spi_device.modalias; identifies the driver.
Initializes spi_device.platform_data; the particular data stored there is driver-specific.
Initializes spi_device.controller_data; some controllers need hints about hardware setup, e.g. for DMA.
Initializes spi_device.irq; depends on how the board is wired.
Initializes spi_device.max_speed_hz; based on limits from the chip datasheet and board-specific signal quality issues.
Identifies which spi_master parents the spi_device; unused
by spi_new_device, and otherwise depends on board wiring.
Initializes spi_device.chip_select; depends on how the board is wired.
Initializes spi_device.mode; based on the chip datasheet, board wiring (some devices support both 3WIRE and standard modes), and possibly presence of an inverter in the chipselect path.
When adding new SPI devices to the device tree, these structures serve
as a partial device template. They hold information which can't always
be determined by drivers. Information that probe can establish (such
as the default transfer wordsize) is not included here.
These structures are used in two places. Their primary role is to
be stored in tables of board-specific device descriptors, which are
declared early in board initialization and then used (much later) to
populate a controller's device tree after the that controller's driver
initializes. A secondary (and atypical) role is as a parameter to
spi_new_device call, which happens after those controller drivers
are active in some dynamic board configuration models.