UM0851 datasheet(91/245 Pages) STMICROELECTRONICS

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UM0851

Communication device drivers

Doc ID 16604 Rev 2

91/245

struct spi_master *master;

u32

max_speed_hz;

chip_select;

mode;

bits_per_word;

int

irq;

void

*controller_state;

void

*controller_data;

const char *modalias;

};

Configuring the SPI controller settings

To configure the SPI controller, you can use the spi_setup() function provided by the SPI

framework. Slave developers can change the previously saved struct spi_device with the

new SPI configuration, like bits_per_word, max_speed_hz, mode.

/* spi is device whose settings are being modified */

static inline int spi_setup(struct spi_device *spi);

Writing data:

To send data over the SPI bus, you can use the spi_write() function provided by the SPI

framework.

/* spi: device to which data will be written

buf: data buffer

len: data buffer size */

static inline int spi_write(struct spi_device *spi, const u8 *buf, size_t len);

Reading data:

To read data over the SPI bus, you can use the spi_read() function provided by the SPI

framework.

/* spi: device from which data will be read

buf: data buffer

len: data buffer size */

static inline int spi_read(struct spi_device *spi, u8 *buf, size_t len);

Writing/reading data - full duplex mode:

Writing and reading simultaneously can be achieved the with following code:

static inline int spi_write_and_read(struct spi_device *spi, const u8 *txbuf, u8

*rxbuf, size_t len)

{

/*create SPI_transfer structure and fill all relevant fields.*/

struct spi_transfer

t = {

.tx_buf

= txbuf,

.rx_buf

= rxbuf,

.len

= len,

};

/*create and initialize spi_message structure.*/

struct spi_messagem;

spi_message_init(&m);

/*adding the transfer structure to the tail of the spi message.*/

spi_message_add_tail(&t, &m);

/*spi_sync function will submit the current message with the spi and will

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