Hard Processor System Booting User Guide: Agilex™ 5 SoCs

ID 813762
Date 12/20/2024
Public
Document Table of Contents

2.2.3. Single SDM Flash

The QSPI controller is shared between the SDM and the HPS and only one of these can access the QSPI device at a time. At power-up, the SDM receives access to the QSPI controller. If the HPS needs access to the QSPI flash device, it must request ownership from the SDM through the HPS-to-SDM mailbox.

Software running on the HPS, such as the FSBL, must request permission from the SDM to access the flash attached to the SDM. After the HPS gains ownership of the QSPI controller, it retains ownership until any of the following events occur:

  • A power cycle
  • A cold reset
  • An HPS reboot generated for an RSU event

For more information, refer to Appendix A.2. HPS Use of SDM QSPI Controller in the Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs.

In the Quad SPI flash example, the OS and file system reside in the Unsorted Block Image File System (UBIFS). The SSBL, which is U-Boot, resides in Raw Partition.

Table 4.  Single SDM Flash
SDM Flash Type Details

Active serial/Quad SPI

The HPS accesses the QSPI device to load the software items. To do this, the HPS requests ownership of the QSPI controller from the SDM.

Figure 4. FPGA Configuration First Layout with Quad SPI