EM9304 SPI API

src/btstack_em9304_spi.h : BTstack's Hardware Abstraction Layer for EM9304 connected via SPI with additional RDY Interrupt line.

#include <stdint.h>
typedef struct {

    /**
     * @brief Open SPI
     */
    int (*open)(void);

    /**
     * @brief Close SPI
     */
    int (*close)(void);

    /**
     * @brief Check if full duplex operation via transceive is supported
     * @return 1 if supported
     */
    int  (*get_fullduplex_support)(void);

    /**
     * @brief Set callback for RDY
     * @param callback or NULL to disable callback
     */
    void (*set_ready_callback)(void (*callback)(void));

    /**
     * @brief Set callback for transfer complete
     * @param callback
     */
    void (*set_transfer_done_callback)(void (*callback)(void));

    /**
     * @brief Set Chip Selet
     * @param enable
     */
    void (*set_chip_select)(int enable);

    /**
     * @brief Poll READY state
     */
    int (*get_ready)(void);

    /**
     * @brief Transmit and Receive bytes via SPI
     * @param tx_data buffer to transmit
     * @param rx_data buffer to receive into
     * @param len 
     */
    void (*transceive)(const uint8_t * tx_data, uint8_t * rx_data, uint16_t len);

    /**
     * @brief Transmit bytes via SPI
     * @param tx_data buffer to transmit
     * @param len 
     */
    void (*transmit)(const uint8_t * tx_data, uint16_t len);

    /**
     * @brief Receive bytes via SPI
     * @param rx_data buffer to receive into
     * @param len 
     */
    void (*receive)(uint8_t * rx_data, uint16_t len);

} btstack_em9304_spi_t;

/**
 * @brief Get EM9304 SPI instance
 */
const btstack_em9304_spi_t * btstack_em9304_spi_embedded_instance(void);