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Arun_Prabakatr's avatar
Arun_Prabakatr
Icon for New Contributor rankNew Contributor
2 months ago

Operating system kernel-level FPGA bridge communication

We are using a custom (Agilex 5) platform and need to access the FPGA bridges from the Linux kernel. We are unable to locate the corresponding device tree nodes or modifications required to access th...
embedded peripheral
operating system
TiensungA_Altera's avatar
TiensungA_Altera
Icon for Occasional Contributor rankOccasional Contributor
1 month ago

hi,

By right, the devmem2 must be used to read/write to the HPS2FPGA bridge using the mapping below for Agilex5. I can see that your mapping is incorrect.  If you are using the LW HPS2FPGa, it starts at 0x1FC0_0000.

You do not need to create any nodes in the device tree. The nodes in the device tree are only required if you are writing/using SOFT IP Device drivers in Linux kernel to access the bridge. Without drivers and with user-space interface, you should be able to use devmem2.

The bridges will be enabled by default if you do a FPGA configuration in Linux. If you perform this in U-boot, you will have to do a bridge enable in uboot before booting the Linux.  The configs that you use above example, CONFIG_FPGA_BRIDGE and _REGION are only required if you are doing FPGA configuration in Linux as they are required by the FPGA manager device driver "stratix10_soc.ko" driver to configure the 2nd stage FPGA core.rbf. In short, the bridges should be enabled if you have configured the FPGA in UBOOT prior to loading Linux.