Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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7.5.2. Software-Managed Clocks

The following list provides more information about the SW-managed clocks:

  • When changing SW-managed clocks, SW must gate the respective clock off, and set the external (ping-pong) counter reset register bit before making any changes.
  • HW mechanisms exist to prevent conflicts between HW control and SW control when switching SW-managed external bypass muxes.

Software-managed clocks have CSR register enables that default to enabled out of reset. The following is the list of SW-managed clocks with enables consumed internally by clock manager:

  • h2f_user[1,0]_clk
  • emac[2,1,0]_clk
  • emac_ptp_clk
  • gpio_db_clk
  • psi_ref_clk

Some peripherals might not be used in certain user configurations, so the clock manager provides CSR register bits for software enables to these peripheral blocks. These enables default to enabled, and in boot mode, they become active to ensure all clocks are active if RAM is cleared for security.

  • usb_clk_en
  • usb31_clk_en
  • dma_clk_en
  • spi_m[1,0]_clk_en
  • spi_s[1,0]_clk_en
  • i3c[1,0]_clk_en
  • i2c[2,1,0]_clk_en
  • uart[2,1,0]_clk_en
  • sp_timer[1,0]_clk_en
  • nand_clk_en
  • sdmmc_clk_en
  • softphy_clk_en