ARCMSR_HBDMU_F0_DOORBELL_CAUSE
doorbell_status = CHIP_REG_READ32(HBD_MessageUnit, 0, outbound_doorbell) & ARCMSR_HBDMU_F0_DOORBELL_CAUSE;
while( doorbell_status & ARCMSR_HBDMU_F0_DOORBELL_CAUSE ) {
doorbell_status = CHIP_REG_READ32(HBD_MessageUnit, 0, outbound_doorbell) & ARCMSR_HBDMU_F0_DOORBELL_CAUSE;