Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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A.4.2.1. FPGA Boot First Mode

During HPS boot up, software can do the following in FSBL:

  1. At this point, FPGA is fully operational, except for any FPGA logic that is inactive due to h2f_gp_out[31:0]= 0.
  2. At whatever software milestone you want to tell the FPGA that it can interact with HPS driven signals, you can set h2f_gp_out[x] = 1. Here are some examples:
    1. After the PLL has been configured, set h2f_gp_out[x] = 1, which indicates to the FPGA logic that h2f_user<1:0>_clock is stable.
    2. After the “bridge enable” command is done, set h2f_gp_out[x]=1, which indicates to the FPGA logic that bridges are stable.
    3. After the GIC is configured by software to receive interrupts, set h2f_gp_out[x] = 1, which indicates to the FPGA logic that the HPS can receive interrupts.
  3. At this point, the HPS is fully operational, and the FPGA is fully operational.
  4. Note that FPGA Boot First mode does not allow FPGA reconfiguration by using HPS.
  5. If there is an HPS reset event, then:
    1. Go to Step 1.