HCI Transport API

src/hci_transport.h : The API allows BTstack to use different transport interfaces.

/* HCI packet types */
typedef struct {
    /**
     * transport name 
     */
    const char * name;

    /**
     * init transport
     * @param transport_config
     */
    void   (*init) (const void *transport_config);

    /**
     * open transport connection
     */
    int    (*open)(void);

    /**
     * close transport connection
     */
    int    (*close)(void);

    /**
     * register packet handler for HCI packets: ACL, SCO, and Events
     */
    void   (*register_packet_handler)(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size));

    /**
     * support async transport layers, e.g. IRQ driven without buffers
     */
    int    (*can_send_packet_now)(uint8_t packet_type);

    /**
     * send packet
     */
    int    (*send_packet)(uint8_t packet_type, uint8_t *packet, int size);

    /**
     * extension for UART transport implementations
     */
    int    (*set_baudrate)(uint32_t baudrate);

    /**
     * extension for UART H5 on CSR: reset BCSP/H5 Link
     */
    void   (*reset_link)(void);

    /**
     * extension for USB transport implementations: config SCO connections
     */
    void   (*set_sco_config)(uint16_t voice_setting, int num_connections);

} hci_transport_t;

typedef enum {
    HCI_TRANSPORT_CONFIG_UART,
    HCI_TRANSPORT_CONFIG_USB,
    HCI_TRANSPORT_CONFIG_LINUX,
} hci_transport_config_type_t;

typedef struct {
    hci_transport_config_type_t type;
} hci_transport_config_t;

typedef struct {
    hci_transport_config_type_t type; // == HCI_TRANSPORT_CONFIG_UART
    uint32_t   baudrate_init;         // initial baud rate
    uint32_t   baudrate_main;         // = 0: same as initial baudrate
    int        flowcontrol;           //
    const char *device_name;
    int        parity;                // see btstack_uart.h BTSTACK_UART_PARITY
} hci_transport_config_uart_t;

typedef struct {
    hci_transport_config_type_t type; // == HCI_TRANSPORT_CONFIG_LINUX
    int device_id;                    // e.g. 0 for HCI0
} hci_transport_config_linux_t;