Modifying resource allocation

Table of Contents

• Introduction
• Changing a particular resource
• Rebuilding the board configuration

Introduction

Various resources of the SOC like the number of DMA channels, number of interrupt router outputs, number of interrupt aggregator virtual interrupt numbers etc. are usually managed by a resource management system or a resource manager. In the case of AM65x devices, this is managed by the System Controller Firmware (SYSFW) running on the M3 core. Once the SYSFW is loaded on M3 and is initialized, we need to send a certain configuration data to the SYSFW regarding the resources we would be using. This is largely an array of resource assignment entries, with each entry specifying the start number of the resource, count or number of resource needed, type of resource, host id of the core which will request for this resource, etc. Later when the request for a specific resource is made, the SYSFW will cross check the request parameters with this already sent configuration data, and the requested resources will only be allocated if that falls within the range in this configuration data. We call this the Resource Management Board Configuration or RM boardcfg.

Changing a particular resource

Note

At the moment the changes need to made manually by editing C files, but soon a Sysconfig GUI based tool will be available to generate this C file.

• To change the assigned number of a particular resource, the sciclient_defaultBoardcfg_rm.c file at path {SDK_ROOT_DIRECTORY}\source\drivers\sciclient\sciclient_default_boardcfg\am65x\ location.
• Around line 120 of the file, you should find a line which says .resasg_entries = {. This is an array of resource assignment entries. Resource assignment entries are structs with members
  • num_resource (Number or Count of resources)
  • type (Type of resource, can be DMA channel, or Interrupt Router Output, etc.)
  • start_resource (Starting number of the resource)
  • host_id (Host ID of the core which can request for this resource)
    

    Resource Assignment Entries
• Once you have identified the resource type which you want to modify, you can see if an entry with that type is already part of the array. If yes, you can go ahead and make the changes directly depending on what you want to do. Change the start number, decrease/increase the number of resources etc. Make sure that resources do not overlap when you change this. Another thing to take care is the host_id in the entry you make. If you add the entry with the current resource range but with a wrong host_id, your host won't be able to request for that particular resource. For each core present in the SoC, there will be two host types - Secure and Non-Secure. These host ids are defined in {SDK_ROOT_DIRECTORY}\source\drivers\sciclient\include\tisci\am65x\tisci_hosts.h file.
• Here is the host id to core mapping:

  HOST ID	Core
  TISCI_HOST_ID_DMSC (0U)	DMSC ARM Cortex M3
  TISCI_HOST_ID_MAIN_0_R5_0 (3U)	Cortex R5FSS0_0 (Non-Secure Context)
  TISCI_HOST_ID_R5_1 (4U)	Cortex R5FSS0_0 (Secure Context)
  TISCI_HOST_ID_R5_2 (5U)	Cortex R5FSS0_1 (Non-Secure Context)
  TISCI_HOST_ID_R5_3 (6U)	Cortex R5FSS0_1 (Secure Context)
  TISCI_HOST_ID_GPU_0 (30U)	GPU_0 (Non-Secure Context)
  TISCI_HOST_ID_GPU_1 (31U)	GPU_1 (Non-Secure Context)
  TISCI_HOST_ID_ICSSG_0 (50U)	ICSSG_0 (Non-Secure Context)
  TISCI_HOST_ID_ICSSG_1 (51U)	ICSSG_1 (Non-Secure Context)
  TISCI_HOST_ID_ICSSG_2 (52U)	ICSSG_2 (Non-Secure Context)

Refer TISCI Host descriptions

Rebuilding the board configuration

• Once the changes are made in the file, we need to generate a hex array corresponding to the file and make sure that the bootloader libraries and the sciclient_set_boardcfg application are updated with these changes. For this one can follow SYSFW Board Config Generation section