/** * Interface for the SPI resource for an entire chip.  The chip accesses * the platform SPI resource one time, but can have multiple clients  * using the SPI bus on top.  When all of the clients are released, the * chip will normally try to release itself from the platforms SPI bus. * In some cases, this isn't desirable - so even though upper components * aren't actively using the SPI bus, they can tell the chip to hold onto * it so they can have immediate access when they need.  * * Any component that aborts a release MUST attempt the release at a later * time if they don't acquire and release the SPI bus naturally after the * abort. *  * @author David Moss */interface ChipSpiResource {    /**   * The SPI bus is about to be automatically released.  Modules that aren't   * using the SPI bus but still want the SPI bus to stick around must call   * abortRelease() within the event.   */  async event void releasing();    /**   * Abort the release of the SPI bus.  This must be called only with the   * releasing() event   */  async command void abortRelease();    /**   * Release the SPI bus if there are no objections   * @return SUCCESS if the SPI bus is released from the chip.   *      FAIL if the SPI bus is already in use.   *      EBUSY if some component aborted the release.   */  async command error_t attemptRelease();  }