SAS command process for expander

Will give a description for sas command process in PMC expander fw. Just for study recoreding.

1.Initialization and register the ISR(sas_pack_isr) function:

tx_application_define()--->sxp_mod_post_create_init--->sas_init()--->sas_portctl_init()

--->pack_init()--->cicint_int_set(): register the pack device driver ISR: -->sas_pack_isr

2.ISR(sas_pack_isr) process:

Interrupt happened--->receive isr msg--->sas_msg_send()--->sas_thread_entry()

--->sas_portctl_process_pack_events()--->sas_ssp_link.frame_rx_fnptr()==sas_ssp_link_event_frame_rx_hndl

--->ssptransport_vtable_ptr->frame_rx_fnptr==sas_ssptarg_transport_frame_received()

--->ssptarg_nexus_init(STE_SCSI_MESSAGE_TYPE_CMD)--->send to ste_mbx_info(ssptarg_mbx_info = ste_parms_ptr->config.ste_mbx_info)

--->ste_main()--->process_message()--->ste_process_scsi_msg()--->process_cmd_msg()--->ste_cmd_process_cmd_msg()--->

process_send_diagnostic_cmd()--->STE_SCSI_MESSAGE_TYPE_DATA_OUT sender:ste_mbx_info,recipient:scsi_mbx_info--->sas_thread_entry()

--->sas_ssptarg_transport_rx_data_out()--->send to ste thread--->process_data_out_msg()--->ste_cmd_process_data_out_msg()

--->process_send_diagnostic_data_out()--->STE_SES_MSG_TYPE_SEND_DIAG:send to ses thread--->ses_msg_queue_process()

--->ses_send_diag_process()