3.6. IPC¶

3.6.1. Overview¶

Overview

Getting Started

Technical Documents

Starting IPC project

3.6.2. IPC Quick Start Guide¶

Overview

This wiki page is meant to be a Quick Start Guide for applications using IPC (Inter Processor Communication) in Processor SDK.

It begins with details about the out-of-box demo provided in the Processor SDK Linux filesystem, followed by rebuilding the demo code and running the built images. ( This covers the use case with the Host running linux OS and the slave cores running RTOS).

Also details about building and running the IPC examples are covered.

The goal is to provides information for users to get familiar with IPC and its build environment, in turn, to help users in developing their projects quickly.

Linux out of box demos

The out of box demo is only available on Keystone-2 EVMs.

1. Connect the EVM Ethernet port 0 to a corporate or local network with DHCP server running, when the Linux kernel boots up, the rootfs start up scripts will get an IP address from the DHCP server and print the IP address to the EVM on-board LCD.

2. Open an Internet browser (e.g. Mozilla Firefox) on a remote computer that connects with the same network as the EVM.

3. Type the IP address displayed on EVM LCD to the browser and click cancel button to launch the Matrix launcher in the remote access mode instead of on the on-board display device.

4. Click the Multi-core Demonstrations, then Multi-core IPC Demo to start the IPC demonstration.

   

   The result from running IPC Demo

   

The source code are located in:

Linux side application: <RTOS_SDK_INSTALL_DIR>/ipc_x_xx_xx_xx/linux/src/tests/MessageQBench.c
DSP side application:   <RTOS_SDK_INSTALL_DIR>/ipc_x_xx_xx_xx/packages/ti/ipc/tests/messageq_single.c

Rebuilding the demo:

1. Install Linux Proc SDK at the default location

2. Include cross-compiler directory in the $PATH

export PATH=<sdk path>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin:$PATH

3. Setup TI RTOS PATH using

export TI_RTOS_PATH=<RTOS_SDK_INSTALL_DIR>
export IPC_INSTALL_PATH=<RTOS_SDK_IPC_DIR>

4. In Linux Proc SDK, start the top level build:

$ make ti-ipc-linux

5. The ARM binary will be located under the directory where the

source code is <RTOS_SDK_INSTALL_DIR>/ipc_x_xx_xx_xx/linux/src/tests/

1. Install RTOS Proc SDK at the default location

2. If RTOS Proc SDK and tools are not installed at its default

location, then the environment variables, SDK_INSTALL_PATH and TOOLS_INSTALL_PATH need to be exported with their installed locations.

export SDK_INSTALL_PATH=<RTOS_SDK_INSTALL_DIR>
export TOOLS_INSTALL_PATH=<RTOS_SDK_INSTALL_DIR>

export TOOLS_INSTALL_PATH=<TI_CCS_INSTALL_DIR>

3. Configure the build environment in

<RTOS_SDK_INSTALL_DIR>/processor_sdk_rtos_<platform>_x_xx_xx_xx directory

$ cd <RTOS_SDK_INSTALL_DIR>/processor_sdk_rtos_<platform>_x_xx_xx_xx
$ source ./setupenv.sh

4. Start the top level build:

$ make ipc_bios

5. The DSP binary will be located under the directory where the

source code is

<RTOS_SDK_INSTALL_DIR>/ipc_x_xx_xx_xx/packages/ti/ipc/tests

Build IPC Linux examples

IPC package and its examples are delivered in RTOS Processor SDK, but can be built from Linux Proc SDK. To build IPC examples, both Linux and RTOS processor SDKs need to be installed. They can be downloaded from SDK download page

To install Linux Proc SDK, please follow the instruction in Linux SDK Getting Started Guide

To Install RTOS Proc SDK, please follow the instructions in RTOS SDK Getting Started Guide

Once the Linux and RTOS Processor SDKs are installed at their default locations, the IPC Linux library, not included in the Linux Proc SDK, can be built on Linux host machine with the following commands:

$ cd <TI_LINUX_PROC_SDK_INSTALL_DIR>
$ make ti-ipc-linux

The IPC examples in RTOS Proc SDK including out-of-box demo can be built with the following commands:

$ cd <TI_LINUX_PROC_SDK_INSTALL_DIR>
$ make ti-ipc-linux-examples

export TI_RTOS_PATH=<TI_RTOS_PROC_SDK_INSTALL_DIR>

Also if using Processor SDK 3.2 or older release, need to also set TI_CCS_PATH to CCSV6 location

export TI_CCS_PATH=<TI_CCS_INSTALL_DIR>/ccsv6

Run IPC Linux examples

1. The executables are in RTOS Proc SDK under the ipc_xx_xx_xx_xx/examples directory.

<device>_<OS>_elf/ex<xx_yyyy>/host/bin/debug/app_host
<device>_<OS>_elf/ex<xx_yyyyyy/<processor_or_component>/bin/debug/<ServerCore_or_component.xe66 for DSP
<device>_<OS>_elf/ex<xx_yyyyyy/<processor_or_component>/bin/debug/<sServerCore_or_component.xem4 for IPU

2. Copy the executables to the target filesystem. It can also be done by running “make ti-ipc-linux-examples_install” to install the binaries to DESTDIR if using NFS filesystem. ( See Moving_Files_to_the_Target_System for details of moving files to filesystem)
3. Load and start the executable on the target DSP/IPU.

For AM57x platforms, Modify the symbolic links in /lib/firmware of the default image names to the built binaries. The images pointed by the symbolic links will be downloaded to and started execution on the corresponding processors by remoteproc during Linux Kernel boots.

DSP image files: dra7-dsp1-fw.xe66  dra7-dsp2-fw.xe66
IPU image files:  dra7-ipu1-fw.xem4  dra7-ipu2-fw.xem4

For OMAP-L138 platform, Modify the symblic link in /lib/firmware of the default image names to the build binary

DSP image files: rproc-dsp-fw

For Keystone-2 platforms, use the Multi-Processor Manager (MPM) Command Line utilities to download and start the DSP executibles. Please refer to /usr/bin/mc_demo_ipc.sh for examples

The available commands are:
   mpmcl reset <dsp core>
   mpmcl status <dsp core>
   mpmcl load <dsp core>
   mpmcl run <dsp core>

4. Run the example From the Linux kernel prompt, run the host executable, app_host. An example from running ex02_messageq:

root@am57xx-evm:~# ./app_host DSP1

The console output:

--> main:
--> Main_main:
--> App_create:
App_create: Host is ready
<-- App_create:
--> App_exec:
App_exec: sending message 1
App_exec: sending message 2
App_exec: sending message 3
App_exec: message received, sending message 4
App_exec: message received, sending message 5
App_exec: message received, sending message 6
App_exec: message received, sending message 7
App_exec: message received, sending message 8
App_exec: message received, sending message 9
App_exec: message received, sending message 10
App_exec: message received, sending message 11
App_exec: message received, sending message 12
App_exec: message received, sending message 13
App_exec: message received, sending message 14
App_exec: message received, sending message 15
App_exec  : message received
App_exec: message received
App_exec: message received
<-- App_exec: 0
--> App_delete:
<-- App_delete:
<-- Main_main:
<-- main:
root@am57xx-evm:~#

Build IPC RTOS examples

The IPC package also includes examples for the use case with Host and the slave cores running RTOS/BIOS. They can be built from the Processor SDK RTOS package.

NOTE: The platform in the directory name may be slightly different from the top level platform name. For example, platform name DRA7XX refer to common examples for DRA7XX & AM57x family of processors.

Once the RTOS Processor SDKs is installed at the default location, the IPC examples can be built with the following commands:

1. Configure the build environment in
   <RTOS_SDK_INSTALL_DIR>/processor_sdk_rtos_<platform>_x_xx_xx_xx directory
     $ cd <RTOS_SDK_INSTALL_DIR>/processor_sdk_rtos_<platform>_x_xx_xx_xx
     $ source ./setupenv.sh
2. Start the top level build:
     $ make ipc_examples

Run IPC RTOS examples

The binary images for the examples are located in the corresponding directories for host and the individual cores. The examples can be run by loading and running the binaries using CCS through JTAG.

Build your own project

After exercising the IPC build and running examples, users can take further look at the source code of the examples as references for their own project.

The sources for examples are under ipc_xx_xx_xx_xx/examples/<device>_<OS>_elf directories. Once modified the same build process described above can be used to rebuild the examples.

3.6.3. IPC for AM57xx¶

Introduction

This article is geared toward AM57xx users that are running Linux on the Cortex A15. The goal is to help users understand how to gain entitlement to the DSP (c66x) and IPU (Cortex M4) subsystems of the AM57xx.

AM572x device has two IPU subsystems (IPUSS), each of which has 2 cores. IPU2 is used as a controller in multi-media applications, so if you have Processor SDK Linux running, chances are that IPU2 already has firmware loaded. However, IPU1 is open for general purpose programming to offload the ARM tasks.

There are many facets to this task: building, loading, debugging, MMUs, memory sharing, etc. This article intends to take incremental steps toward understanding all of those pieces.

Software Dependencies to Get Started

Prerequisites

• Processor SDK Linux for AM57xx (Version 3.01 or newer needed)
• Processor SDK RTOS for AM57xx
• Code Composer Studio (choose version as specified on Proc SDK download page)

For reference within the context of this wiki page, the Linux SDK is installed at the following location:

/mnt/data/user/ti-processor-sdk-linux-am57xx-evm-xx.xx.xx.xx
├── bin
├── board-support
├── docs
├── example-applications
├── filesystem
├── ipc-build.txt
├── linux-devkit
├── Makefile
├── Rules.make
└── setup.sh

The RTOS SDK is installed at:

/mnt/data/user/my_custom_install_sdk_rtos_am57xx_xx.xx
├── bios_6_xx_xx_xx
├── cg_xml
├── ctoolslib_x_x_x_x
├── dsplib_c66x_x_x_x_x
├── edma3_lld_2_xx_xx_xx
├── framework_components_x_xx_xx_xx
├── imglib_c66x_x_x_x_x
├── ipc_3_xx_xx_xx
├── mathlib_c66x_3_x_x_x
├── ndk_2_xx_xx_xx
├── opencl_rtos_am57xx_01_01_xx_xx
├── openmp_dsp_am57xx_2_04_xx_xx
├── pdk_am57xx_x_x_x
├── processor_sdk_rtos_am57xx_x_xx_xx_xx
├── uia_2_xx_xx_xx
├── xdais_7_xx_xx_xx

CCS is installed at:

/mnt/data/user/ti/my_custom_ccs_x.x.x_install
├── ccsvX
│   ├── ccs_base
│   ├── doc
│   ├── eclipse
│   ├── install_info
│   ├── install_logs
│   ├── install_scripts
│   ├── tools
│   ├── uninstall_ccs
│   ├── uninstall_ccs.dat
│   ├── uninstallers
│   └── utils
├── Code Composer Studio x.x.x.desktop
└── xdctools_x_xx_xx_xx_core
    ├── bin
    ├── config.jar
    ├── docs
    ├── eclipse
    ├── etc
    ├── gmake
    ├── include
    ├── package
    ├── packages
    ├── package.xdc
    ├── tconfini.tcf
    ├── xdc
    ├── xdctools_3_xx_xx_xx_manifest.html
    ├── xdctools_3_xx_xx_xx_release_notes.html
    ├── xs
    └── xs.x86U

Typical Boot Flow on AM572x for ARM Linux users

AM57xx SOC’s have multiple processor cores - Cortex A15, C66x DSP’s and ARM M4 cores. The A15 typically runs a HLOS like Linux/QNX/Android and the remotecores(DSP’s and M4’s) run a RTOS. In the normal operation, boot loader(U-Boot/SPL) boots and loads the A15 with the HLOS. The A15 boots the DSP and the M4 cores.

In this sequence, the interval between the Power on Reset and the remotecores (i.e. the DSP’s and the M4’s) executing is dependent on the HLOS initialization time.

Getting Started with IPC Linux Examples

The figure below illustrates how remoteproc/rpmsg driver from ARM Linux kernel communicates with IPC driver on slave processor (e.g. DSP, IPU, etc) running RTOS.

In order to setup IPC on slave cores, we provide some pre-built examples in IPC package that can be run from ARM Linux. The subsequent sections describe how to build and run this examples and use that as a starting point for this effort.

Building the Bundled IPC Examples

The instructions to build IPC examples found under ipc_3_xx_xx_xx/examples/DRA7XX_linux_elf have been provided in the `Processor_SDK IPC Quick Start Guide <https://processors.wiki.ti.com/index.php/Processor_SDK_IPC_Quick_Start_Guide#Build_IPC_Linux_examples>`__.

Let’s focus on one example in particular, ex02_messageq, which is located at <rtos-sdk-install-dir>/ipc_3_xx_xx_xx/examples/DRA7XX_linux_elf/ex02_messageq. Here are the key files that you should see after a successful build:

├── dsp1
│   └── bin
│       ├── debug
│       │   └── server_dsp1.xe66
│       └── release
│           └── server_dsp1.xe66
├── dsp2
│   └── bin
│       ├── debug
│       │   └── server_dsp2.xe66
│       └── release
│           └── server_dsp2.xe66
├── host
│       ├── debug
│       │   └── app_host
│       └── release
│           └── app_host
├── ipu1
│   └── bin
│       ├── debug
│       │   └── server_ipu1.xem4
│       └── release
│           └── server_ipu1.xem4
└── ipu2
    └── bin
        ├── debug
        │   └── server_ipu2.xem4
        └── release
            └── server_ipu2.xem4

Running the Bundled IPC Examples

On the target, let’s create a directory called ipc-starter:

root@am57xx-evm:~# mkdir -p /home/root/ipc-starter
root@am57xx-evm:~# cd /home/root/ipc-starter/

You will need to copy the ex02_messageq directory of your host PC to that directory on the target (through SD card, NFS export, SCP, etc.). You can copy the entire directory, though we’re primarily interested in these files:

• dsp1/bin/debug/server_dsp1.xe66
• dsp2/bin/debug/server_dsp2.xe66
• host/bin/debug/app_host
• ipu1/bin/debug/server_ipu1.xem4
• ipu2/bin/debug/server_ipu2.xem4

The remoteproc driver is hard-coded to look for specific files when loading the DSP/M4. Here are the files it looks for:

• /lib/firmware/dra7-dsp1-fw.xe66
• /lib/firmware/dra7-dsp2-fw.xe66
• /lib/firmware/dra7-ipu1-fw.xem4
• /lib/firmware/dra7-ipu2-fw.xem4

These are generally a soft link to the intended executable. So for example, let’s update the DSP1 executable on the target:

root@am57xx-evm:~# cd /lib/firmware/
root@am57xx-evm:/lib/firmware# rm dra7-dsp1-fw.xe66
root@am57xx-evm:/lib/firmware# ln -s /home/root/ipc-starter/ex02_messageq/dsp1/bin/debug/server_dsp1.xe66 dra7-dsp1-fw.xe66

To reload DSP1 with this new executable, we perform the following steps:

root@am57xx-evm:/lib/firmware# cd /sys/bus/platform/drivers/omap-rproc/
root@am57xx-evm:/sys/bus/platform/drivers/omap-rproc# echo 40800000.dsp > unbind
[27639.985631] omap_hwmod: mmu0_dsp1: _wait_target_disable failed
[27639.991534] omap-iommu 40d01000.mmu: 40d01000.mmu: version 3.0
[27639.997610] omap-iommu 40d02000.mmu: 40d02000.mmu: version 3.0
[27640.017557] omap_hwmod: mmu1_dsp1: _wait_target_disable failed
[27640.030571] omap_hwmod: mmu0_dsp1: _wait_target_disable failed
[27640.036605]  remoteproc2: stopped remote processor 40800000.dsp
[27640.042805]  remoteproc2: releasing 40800000.dsp
root@am57xx-evm:/sys/bus/platform/drivers/omap-rproc# echo 40800000.dsp > bind
[27645.958613] omap-rproc 40800000.dsp: assigned reserved memory node dsp1_cma@99000000
[27645.966452]  remoteproc2: 40800000.dsp is available
[27645.971410]  remoteproc2: Note: remoteproc is still under development and considered experimental.
[27645.980536]  remoteproc2: THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn't yet guaranteed.
root@am57xx-evm:/sys/bus/platform/drivers/omap-rproc# [27646.008171]  remoteproc2: powering up 40800000.dsp
[27646.013038]  remoteproc2: Booting fw image dra7-dsp1-fw.xe66, size 4706800
[27646.028920] omap_hwmod: mmu0_dsp1: _wait_target_disable failed
[27646.034819] omap-iommu 40d01000.mmu: 40d01000.mmu: version 3.0
[27646.040772] omap-iommu 40d02000.mmu: 40d02000.mmu: version 3.0
[27646.058323]  remoteproc2: remote processor 40800000.dsp is now up
[27646.064772] virtio_rpmsg_bus virtio2: rpmsg host is online
[27646.072271]  remoteproc2: registered virtio2 (type 7)
[27646.078026] virtio_rpmsg_bus virtio2: creating channel rpmsg-proto addr 0x3d

More info related to loading firmware to the various cores can be found here.

Finally, we can run the example on DSP1:

root@am57xx-evm:/sys/bus/platform/drivers/omap-rproc# cd /home/root/ipc-starter/ex02_messageq/host/bin/debug
root@am57xx-evm:~/ipc-starter/ex02_messageq/host/bin/debug# ./app_host DSP1
--> main:
[33590.700700] omap_hwmod: mmu0_dsp2: _wait_target_disable failed
[33590.706609] omap-iommu 41501000.mmu: 41501000.mmu: version 3.0
[33590.718798] omap-iommu 41502000.mmu: 41502000.mmu: version 3.0
--> Main_main:
--> App_create:
App_create: Host is ready
<-- App_create:
--> App_exec:
App_exec: sending message 1
App_exec: sending message 2
App_exec: sending message 3
App_exec: message received, sending message 4
App_exec: message received, sending message 5
App_exec: message received, sending message 6
App_exec: message received, sending message 7
App_exec: message received, sending message 8
App_exec: message received, sending message 9
App_exec: message received, sending message 10
App_exec: message received, sending message 11
App_exec: message received, sending message 12
App_exec: message received, sending message 13
App_exec: message received, sending message 14
App_exec: message received, sending message 15
App_exec: message received
App_exec: message received
App_exec: message received
<-- App_exec: 0
--> App_delete:
<-- App_delete:
<-- Main_main:
<-- main:

Understanding the Memory Map

Overall Linux Memory Map

root@am57xx-evm:~# cat /proc/iomem
[snip...]
58060000-58078fff : core
58820000-5882ffff : l2ram
58882000-588820ff : /ocp/mmu@58882000
80000000-9fffffff : System RAM
  80008000-808d204b : Kernel code
  80926000-809c96bf : Kernel data
a0000000-abffffff : CMEM
ac000000-ffcfffff : System RAM

CMA Carveouts

root@am57xx-evm:~# dmesg | grep -i cma
[    0.000000] Reserved memory: created CMA memory pool at 0x0000000095800000, size 56 MiB
[    0.000000] Reserved memory: initialized node ipu2_cma@95800000, compatible id shared-dma-pool
[    0.000000] Reserved memory: created CMA memory pool at 0x0000000099000000, size 64 MiB
[    0.000000] Reserved memory: initialized node dsp1_cma@99000000, compatible id shared-dma-pool
[    0.000000] Reserved memory: created CMA memory pool at 0x000000009d000000, size 32 MiB
[    0.000000] Reserved memory: initialized node ipu1_cma@9d000000, compatible id shared-dma-pool
[    0.000000] Reserved memory: created CMA memory pool at 0x000000009f000000, size 8 MiB
[    0.000000] Reserved memory: initialized node dsp2_cma@9f000000, compatible id shared-dma-pool
[    0.000000] cma: Reserved 24 MiB at 0x00000000fe400000
[    0.000000] Memory: 1713468K/1897472K available (6535K kernel code, 358K rwdata, 2464K rodata, 332K init, 289K bss, 28356K reserved, 155648K  cma-reserved, 1283072K highmem)
[    5.492945] omap-rproc 58820000.ipu: assigned reserved memory node ipu1_cma@9d000000
[    5.603289] omap-rproc 55020000.ipu: assigned reserved memory node ipu2_cma@95800000
[    5.713411] omap-rproc 40800000.dsp: assigned reserved memory node dsp1_cma@9b000000
[    5.771990] omap-rproc 41000000.dsp: assigned reserved memory node dsp2_cma@9f000000

From the output above, we can derive the location and size of each CMA carveout:

For details on how to adjust the sizes and locations of the DSP/IPU CMA carveouts, please see the corresponding section for changing the DSP or IPU memory map.

To adjust the size of the “Default CMA” section, this is done as part of the Linux config:

linux/arch/arm/configs/tisdk_am57xx-evm_defconfig

#
# Default contiguous memory area size:
#
CONFIG_CMA_SIZE_MBYTES=24
CONFIG_CMA_SIZE_SEL_MBYTES=y

CMEM

To view the allocation at run-time:

root@am57xx-evm:~# cat /proc/cmem

Block 0: Pool 0: 1 bufs size 0xc000000 (0xc000000 requested)

Pool 0 busy bufs:

Pool 0 free bufs:
id 0: phys addr 0xa0000000

This shows that we have defined a CMEM block at physical base address of 0xA0000000 with total size 0xc000000 (192 MB). This block contains a buffer pool consisting of 1 buffer. Each buffer in the pool (only one in this case) is defined to have a size of 0xc000000 (192 MB).

Here is where those sizes/addresses were defined for the AM57xx EVM:

linux/arch/arm/boot/dts/am57xx-evm-cmem.dtsi

/ {
       reserved-memory {
               #address-cells = <2>;
               #size-cells = <2>;
               ranges;

               cmem_block_mem_0: cmem_block_mem@a0000000 {
                       reg = <0x0 0xa0000000 0x0 0x0c000000>;
                       no-map;
                       status = "okay";
               };

               cmem_block_mem_1_ocmc3: cmem_block_mem@40500000 {
                       reg = <0x0 0x40500000 0x0 0x100000>;
                       no-map;
                       status = "okay";
               };
       };

       cmem {
               compatible = "ti,cmem";
               #address-cells = <1>;
               #size-cells = <0>;

               #pool-size-cells = <2>;

               status = "okay";

               cmem_block_0: cmem_block@0 {
                       reg = <0>;
                       memory-region = <&cmem_block_mem_0>;
                       cmem-buf-pools = <1 0x0 0x0c000000>;
               };

               cmem_block_1: cmem_block@1 {
                       reg = <1>;
                       memory-region = <&cmem_block_mem_1_ocmc3>;
               };
       };
};

Changing the DSP Memory Map

First, it is important to understand that there are a pair of Memory Management Units (MMUs) that sit between the DSP subsystems and the L3 interconnect. One of these MMUs is for the DSP core and the other is for its local EDMA. They both serve the same purpose of translating virtual addresses (i.e. the addresses as viewed by the DSP subsystem) into physical addresses (i.e. addresses as viewed from the L3 interconnect).

DSP Physical Addresses

The physical location where the DSP code/data will actually reside is defined by the CMA carveout. To change this location, you must change the definition of the carveout. The DSP carveouts are defined in the Linux dts file. For example for the AM57xx EVM:

        dsp1_cma_pool: dsp1_cma@99000000 {
                compatible = "shared-dma-pool";
                reg = <0x0 0x99000000 0x0 0x4000000>;
                reusable;
                status = "okay";
        };

        dsp2_cma_pool: dsp2_cma@9f000000 {
                compatible = "shared-dma-pool";
                reg = <0x0 0x9f000000 0x0 0x800000>;
                reusable;
                status = "okay";
        };
};

You are able to change both the size and location. Be careful not to overlap any other carveouts!

Additionally, when you change the carveout location, there is a corresponding change that must be made to the resource table. For starters, if you’re making a memory change you will need a custom resource table. The resource table is a large structure that is the “bridge” between physical memory and virtual memory. This structure is utilized for configuring the MMUs that sit in front of the DSP subsystem. There is detailed information available in the article IPC Resource customTable.

Once you’ve created your custom resource table, you must update the address of PHYS_MEM_IPC_VRING to be the same base address as your corresponding CMA.

#if defined (VAYU_DSP_1)
#define PHYS_MEM_IPC_VRING      0x99000000
#elif defined (VAYU_DSP_2)
#define PHYS_MEM_IPC_VRING      0x9F000000
#endif

DSP Virtual Addresses

These addresses are the ones seen by the DSP subsystem, i.e. these will be the addresses in your linker command files, etc.

You must ensure that the sizes of your sections are consistent with the corresponding definitions in the resource table. You should create your own resource table in order to modify the memory map. This is describe in the wiki page IPC Resource customTable. You can look at an existing resource table inside IPC:

ipc/packages/ti/ipc/remoteproc/rsc_table_vayu_dsp.h

{
    TYPE_CARVEOUT,
    DSP_MEM_TEXT, 0,
    DSP_MEM_TEXT_SIZE, 0, 0, "DSP_MEM_TEXT",
},

{
    TYPE_CARVEOUT,
    DSP_MEM_DATA, 0,
    DSP_MEM_DATA_SIZE, 0, 0, "DSP_MEM_DATA",
},

{
    TYPE_CARVEOUT,
    DSP_MEM_HEAP, 0,
    DSP_MEM_HEAP_SIZE, 0, 0, "DSP_MEM_HEAP",
},

{
    TYPE_CARVEOUT,
    DSP_MEM_IPC_DATA, 0,
    DSP_MEM_IPC_DATA_SIZE, 0, 0, "DSP_MEM_IPC_DATA",
},

{
    TYPE_TRACE, TRACEBUFADDR, 0x8000, 0, "trace:dsp",
},


{
    TYPE_DEVMEM,
    DSP_MEM_IPC_VRING, PHYS_MEM_IPC_VRING,
    DSP_MEM_IPC_VRING_SIZE, 0, 0, "DSP_MEM_IPC_VRING",
},

Let’s have a look at some of these to understand them better. For example:

{
    TYPE_CARVEOUT,
    DSP_MEM_TEXT, 0,
    DSP_MEM_TEXT_SIZE, 0, 0, "DSP_MEM_TEXT",
},

Key points to note are:

1. The “TYPE_CARVEOUT” indicates that the physical memory backing this entry will come from the associated CMA pool.
2. DSP_MEM_TEXT is a #define earlier in the code providing the address for the code section. It is 0x95000000 by default. This must correspond to a section from your DSP linker command file, i.e. EXT_CODE (or whatever name you choose to give it) must be linked to the same address.
3. DSP_MEM_TEXT_SIZE is the size of the MMU pagetable entry being created (1MB in this particular instance). The actual amount of linked code in the corresponding section of your executable must be less than or equal to this size.

Let’s take another:

{
    TYPE_TRACE, TRACEBUFADDR, 0x8000, 0, "trace:dsp",
},

Key points are:

1. The “TYPE_TRACE” indicates this is for trace info.
2. The TRACEBUFADDR is defined earlier in the file as &ti_trace_SysMin_Module_State_0_outbuf__A. That corresponds to the symbol used in TI-RTOS for the trace buffer.
3. The “0x8000” is the size of the MMU mapping. The corresponding size in the cfg file should be the same (or less). It looks like this: SysMin.bufSize  = 0x8000;

Finally, let’s look at a TYPE_DEVMEM example:

{
    TYPE_DEVMEM,
    DSP_PERIPHERAL_L4CFG, L4_PERIPHERAL_L4CFG,
    SZ_16M, 0, 0, "DSP_PERIPHERAL_L4CFG",
},

Key points:

1. The “TYPE_DEVMEM” indicates that we are making an MMU mapping, but this does not come from the CMA pool. This is intended for mapping peripherals, etc. that already exist in the device memory map.
2. DSP_PERIPHERAL_L4CFG (0x4A000000) is the virtual address while L4_PERIPHERAL_L4CFG (0x4A000000) is the physical address. This is an identity mapping, meaning that peripherals can be referenced by the DSP using their physical address.

DSP Access to Peripherals

The default resource table creates the following mappings:

In other words, the peripherals can be accessed at their physical addresses since we use an identity mapping.

Inspecting the DSP IOMMU Page Tables at Run-Time

You can dump the DSP IOMMU page tables with the following commands:

In general, MMU0 and MMU1 are being programmed identically so you really only need to take a look at one or the other to understand the mapping for a given DSP.

For example:

root@am57xx-evm:~# cat /sys/kernel/debug/omap_iommu/40d01000.mmu/pagetable
L:      da:     pte:
--------------------------
1: 0x48000000 0x48000002
1: 0x48100000 0x48100002
1: 0x48400000 0x48400002
1: 0x48500000 0x48500002
1: 0x48600000 0x48600002
1: 0x48700000 0x48700002
1: 0x48800000 0x48800002
1: 0x48900000 0x48900002
1: 0x48a00000 0x48a00002
1: 0x48b00000 0x48b00002
1: 0x48c00000 0x48c00002
1: 0x48d00000 0x48d00002
1: 0x48e00000 0x48e00002
1: 0x48f00000 0x48f00002
1: 0x4a000000 0x4a040002
1: 0x4a100000 0x4a040002
1: 0x4a200000 0x4a040002
1: 0x4a300000 0x4a040002
1: 0x4a400000 0x4a040002
1: 0x4a500000 0x4a040002
1: 0x4a600000 0x4a040002
1: 0x4a700000 0x4a040002
1: 0x4a800000 0x4a040002
1: 0x4a900000 0x4a040002
1: 0x4aa00000 0x4a040002
1: 0x4ab00000 0x4a040002
1: 0x4ac00000 0x4a040002
1: 0x4ad00000 0x4a040002
1: 0x4ae00000 0x4a040002
1: 0x4af00000 0x4a040002

The first column tells us whether the mapping is a Level 1 or Level 2 descriptor. All the lines above are a first level descriptor, so we look at the associated format from the TRM:

The “da” (“device address”) column reflects the virtual address. It is derived from the index into the table, i.e. there does not exist a “da” register or field in the page table. Each MB of the address space maps to an entry in the table. The “da” column is displayed to make it easy to find the virtual address of interest.

The “pte” (“page table entry”) column can be decoded according to Table 20-4 shown above. For example:

1: 0x4a000000 0x4a040002

The 0x4a040002 shows us that it is a Supersection with base address 0x4A000000. This gives us a 16 MB memory page. Note the repeated entries afterward. That’s a requirement of the MMU. Here’s an excerpt from the TRM:

Changing Cortex M4 IPU Memory Map

In order to fully understand the memory mapping of the Cortex M4 IPU Subsystems, it’s helpful to recognize that there are two distinct/independent levels of memory translation. Here’s a snippet from the TRM to illustrate:

Cortex M4 IPU Physical Addresses

The physical location where the M4 code/data will actually reside is defined by the CMA carveout. To change this location, you must change the definition of the carveout. The M4 carveouts are defined in the Linux dts file. For example for the AM57xx EVM:

        ipu2_cma_pool: ipu2_cma@95800000 {
                compatible = "shared-dma-pool";
                reg = <0x0 95800000 0x0 0x3800000>;
                reusable;
                status = "okay";
        };

        ipu1_cma_pool: ipu1_cma@9d000000 {
                compatible = "shared-dma-pool";
                reg = <0x0 9d000000 0x0 0x2000000>;
                reusable;
                status = "okay";
        };
};

Once you’ve created your custom resource table, you must update the address of PHYS_MEM_IPC_VRING to be the same base address as your corresponding CMA.

#if defined(VAYU_IPU_1)
#define PHYS_MEM_IPC_VRING      0x9D000000
#elif defined (VAYU_IPU_2)
#define PHYS_MEM_IPC_VRING      0x95800000
#endif

Cortex M4 IPU Virtual Addresses

Unicache MMU

The Unicache MMU sits closest to the Cortex M4. It provides the first level of address translation. The Unicache MMU is actually “self programmed” by the Cortex M4. The Unicache MMU is also referred to as the Attribute MMU (AMMU). There are a fixed number of small, medium and large pages. Here’s a snippet showing some of the key mappings:

ipc_3_43_02_04/examples/DRA7XX_linux_elf/ex02_messageq/ipu1/IpuAmmu.cfg

/*********************** Large Pages *************************/
/* Instruction Code: Large page  (512M); cacheable */
/* config large page[0] to map 512MB VA 0x0 to L3 0x0 */
AMMU.largePages[0].pageEnabled = AMMU.Enable_YES;
AMMU.largePages[0].logicalAddress = 0x0;
AMMU.largePages[0].translationEnabled = AMMU.Enable_NO;
AMMU.largePages[0].size = AMMU.Large_512M;
AMMU.largePages[0].L1_cacheable = AMMU.CachePolicy_CACHEABLE;
AMMU.largePages[0].L1_posted = AMMU.PostedPolicy_POSTED;

/* Peripheral regions: Large Page (512M); non-cacheable */
/* config large page[1] to map 512MB VA 0x60000000 to L3 0x60000000 */
AMMU.largePages[1].pageEnabled = AMMU.Enable_YES;
AMMU.largePages[1].logicalAddress = 0x60000000;
AMMU.largePages[1].translationEnabled = AMMU.Enable_NO;
AMMU.largePages[1].size = AMMU.Large_512M;
AMMU.largePages[1].L1_cacheable = AMMU.CachePolicy_NON_CACHEABLE;
AMMU.largePages[1].L1_posted = AMMU.PostedPolicy_POSTED;

/* Private, Shared and IPC Data regions: Large page (512M); cacheable */
/* config large page[2] to map 512MB VA 0x80000000 to L3 0x80000000 */
AMMU.largePages[2].pageEnabled = AMMU.Enable_YES;
AMMU.largePages[2].logicalAddress = 0x80000000;
AMMU.largePages[2].translationEnabled = AMMU.Enable_NO;
AMMU.largePages[2].size = AMMU.Large_512M;
AMMU.largePages[2].L1_cacheable = AMMU.CachePolicy_CACHEABLE;
AMMU.largePages[2].L1_posted = AMMU.PostedPolicy_POSTED;

These 3 pages are “identity” mappings, performing a passthrough of requests to the associated address ranges. These intermediate addresses get mapped to their physical addresses in the next level of translation (IOMMU).

The AMMU ranges for code and data need to be identity mappings because otherwise the remoteproc loader wouldn’t be able to match up the sections from the ELF file with the associated IOMMU mapping. These mappings should suffice for any application, i.e. no need to adjust these. The more likely area for modification is the resource table in the next section. The AMMU mappings are needed mainly to understand the full picture with respect to the Cortex M4 memory map.

IOMMU

The IOMMU sits closest to the L3 interconnect. It takes the intermediate address output from the AMMU and translates it to the physical address used by the L3 interconnect. The IOMMU is programmed by the ARM based on the associated resource table. If you’re planning any memory changes then you’ll want to make a custom resource table as described in the wiki page IPC Resource customTable.

The default resource table (which can be adapted to make a custom table) can be found at this location:

ipc/packages/ti/ipc/remoteproc/rsc_table_vayu_ipu.h

#define IPU_MEM_TEXT            0x0
#define IPU_MEM_DATA            0x80000000

#define IPU_MEM_IOBUFS          0x90000000

#define IPU_MEM_IPC_DATA        0x9F000000
#define IPU_MEM_IPC_VRING       0x60000000
#define IPU_MEM_RPMSG_VRING0    0x60000000
#define IPU_MEM_RPMSG_VRING1    0x60004000
#define IPU_MEM_VRING_BUFS0     0x60040000
#define IPU_MEM_VRING_BUFS1     0x60080000

#define IPU_MEM_IPC_VRING_SIZE  SZ_1M
#define IPU_MEM_IPC_DATA_SIZE   SZ_1M

#if defined(VAYU_IPU_1)
#define IPU_MEM_TEXT_SIZE       (SZ_1M)
#elif defined(VAYU_IPU_2)
#define IPU_MEM_TEXT_SIZE       (SZ_1M * 6)
#endif

#if defined(VAYU_IPU_1)
#define IPU_MEM_DATA_SIZE       (SZ_1M * 5)
#elif defined(VAYU_IPU_2)
#define IPU_MEM_DATA_SIZE       (SZ_1M * 48)
#endif

<snip...>

{
    TYPE_CARVEOUT,
    IPU_MEM_TEXT, 0,
    IPU_MEM_TEXT_SIZE, 0, 0, "IPU_MEM_TEXT",
},

{
    TYPE_CARVEOUT,
    IPU_MEM_DATA, 0,
    IPU_MEM_DATA_SIZE, 0, 0, "IPU_MEM_DATA",
},

{
    TYPE_CARVEOUT,
    IPU_MEM_IPC_DATA, 0,
    IPU_MEM_IPC_DATA_SIZE, 0, 0, "IPU_MEM_IPC_DATA",
},

The 3 entries above from the resource table all come from the associated IPU CMA pool (i.e. as dictated by the TYPE_CARVEOUT). The second parameter represents the virtual address (i.e. input address to the IOMMU). These addresses must be consistent with both the AMMU mapping as well as the linker command file. The ex02_messageq example from ipc defines these memory sections in the file examples/DRA7XX_linux_elf/ex02_messageq/shared/config.bld.

You can dump the IPU IOMMU page tables with the following commands:

Please see the corresponding DSP documentation for more details on interpreting the output.

Cortex M4 IPU Access to Peripherals

The default resource table creates the following mappings:

Example: Accessing UART5 from IPU

1. For this example, it’s assumed the pin-muxing was already setup in the bootloader. If that’s not the case, you would need to do that here.
2. The UART5 module needs to be enabled via the CM_L4PER_UART5_CLKCTRL register. This is located at physical address 0x4A009870. So from the M4 we would program this register at virtual address 0x6A009870. Writing a value of 2 to this register will enable the peripheral.
3. After completing the previous step, the UART5 registers will become accessible. Normally UART5 is accessible at physical base address 0x48066000. This would correspondingly be accessed from the IPU at 0x68066000.

Power Management

The IPUs and DSPs auto-idle by default. This can prevent you from being able to connect to the device using JTAG or from accessing local memory via devmem2. There are some options sprinkled throughout sysfs that are needed in order to force these subsystems on, as is sometimes needed for development and debug purposes.

There are some hard-coded device names that originate in the device tree (dra7.dtsi) that are needed for these operations:

To map these System FS names to the associated remoteproc entry, you can run the following commands:

root@am57xx-evm:~# ls -l /sys/kernel/debug/remoteproc/
root@am57xx-evm:~# cat /sys/kernel/debug/remoteproc/remoteproc*/name

The results of the commands will be a one-to-one mapping. For example, 58820000.ipu corresponds with remoteproc0.

Similarly, to see the power state of each of the cores:

root@am57xx-evm:~# cat /sys/class/remoteproc/remoteproc*/state

The state can be suspended, running, offline, etc. You can only attach JTAG if the state is “running”. If it shows as “suspended” then you must force it to run. For example, let’s say DSP0 is “suspended”. You can run the following command to force it on:

root@am57xx-evm:~# echo on > /sys/bus/platform/devices/40800000.dsp/power/control

The same is true for any of the cores, but replace 40800000.dsp with the associated System FS name from the chart above.

Adding IPC to an Existing TI-RTOS Application on slave cores

Adding IPC to an existing TI RTOS application on the DSP

A common thing people want to do is take an existing DSP application and add IPC to it. This is common when migrating from a DSP only solution to a heterogeneous SoC with an Arm plus a DSP. This is the focus of this section.

In order to describe this process, we need an example test case to work with. For this purpose, we’ll be using the GPIO_LedBlink_evmAM572x_c66xExampleProject example that’s part of the PDK (installed as part of the Processor SDK RTOS). You can find it at c:\ti\pdk_am57xx_1_0_4\packages\MyExampleProjects\GPIO_LedBlink_evmAM572x_c66xExampleProject. This example uses SYS/BIOS and blinks the USER0 LED on the AM572x GP EVM, it’s labeled D4 on the EVM silkscreen just to the right of the blue reset button.

There were several steps taken to make this whole process work, each of which will be described in following sections

1. Build and run the out-of-box LED blink example on the EVM using Code Composer Studio (CCS)
2. Take the ex02_message example from the IPC software bundle and turn it into a CCS project. Build it and modify the Linux startup code to use this new image. This is just a sanity check step to make sure we can build the IPC examples in CCS and have them run at boot up on the EVM.
3. In CCS, make a clone of the out-of-box LED example and rename it to denote it’s the IPC version of the example. Then using the ex02_messageq example as a reference, add in the IPC pieces to the LED example. Build from CCS then add it to the Linux firmware folder.

Running LED Blink PDK Example from CCS

TODO - Fill this section in with instructions on how to run the LED blink example using JTAG and CCS after the board has booted Linux.

Make CCS project out of ex02_messageq IPC example

TODO - fill this section in with instructions on how to make a CCS project out of the IPC example source files.

Add IPC to the LED Blink Example

The first step is to clone our out-of-box LED blink CCS project and rename it to denote it’s using IPC. The easiest way to do this is using CCS. Here are the steps...

• In the Edit perspective, go into your Project Explorer window and right click on your GPIO_LedBlink_evmAM572x+c66xExampleProject project and select copy from the pop-up menu. Maske sure the project is not is a closed state.
• Rick click in and empty area of the project explorer window and select past.
• A dialog box pops up, modify the name to denote it’s using IPC. A good name is GPIO_LedBlink_evmAM572x+c66xExampleProjec_with_ipc.

This is the project we’ll be working with from here on. The next thing we want to do is select the proper RTSC platform and other components. To do this, follow these steps.

• Right click on the GPIO_LedBlink_evmAM572x+c66xExampleProjec_with_ipc project and select Properties
• In the left hand pane, click on CCS General.
• On the right hand side, click on the RTSC tab
• For XDCtools version: select 3.32.0.06_core
• In the list of Products and Repositories, check the following...
  • IPC 3.43.2.04
  • SYS/BIOS 6.45.1.29
  • am57xx PDK 1.0.4
• For Target, select ti.targets.elf.C66
• For Platform, select ti.platforms.evmDRA7XX
• Once the platform is selected, edit its name buy hand and append :dsp1 to the end. After this it should be ti.platforms.evmDRA7XX:dsp1
• Go ahead and leave the Build-profile set to debug.
• Hit the OK button.

Now we want to copy configuration and source files from the ex02_messageq IPC example into our project. The IPC example is located at C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq. To copy files into your CCS project, you can simply select the files you want in Windows explorer then drag and drop them into your project in CCS.

Copy these files into your CCS project...

• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\shared\AppCommon.h
• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\shared\config.bld
• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\shared\ipc.cfg.xs

Now copy these files into your CCS project...

• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\dsp1\Dsp1.cfg
• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\dsp1\MainDsp1.c
• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\dsp1\Server.c
• C:\ti\ipc_3_43_02_04\examples\DRA7XX_linux_elf\ex02_messageq\dsp1\Server.h

Finally, you will likely want to use a custom resource table so copy these files into your CCS project...

• C:\ti\ipc_3_43_02_04\packages\ti\ipc\remoteproc\rsc_table_vayu_dsp.h
• C:\ti\ipc_3_43_02_04\packages\ti\ipc\remoteproc\rsc_types.h

The rsc_table_vayu_dsp.h file defines an initialized structure so let’s make a .c source file.

• In your CCS project, rename rsc_table_vayu_dsp.h to rsc_table_vayu_dsp.c

Now we want to merge the IPC example configuration file with the LED blink example configuration file. Follow these steps...

• Open up Dsp1.cfg using a text editor (don’t open it using the GUI). Right click on it and select Open With -> XDCscript Editor
• We want to copy the entire contents into the clipboard. Select all and copy.
• Now just like above, open the gpio_test_evmAM572x.cfg config file in the text editor. Go to the very bottom and paste in the contents from the Dsp1.cfg file. Basically we’ve appended the contents of Dsp1.cfg into gpio_test_evmAM572x.cfg.

We’ve now added in all the necessary configuration and source files into our project. Don’t expect it to build at this point, we have to make edits first. These edits are listed below.

NOTE, you can download the full CCS project with source files to use as a reference.
See link towards the end of this section.

• Edit gpio_test_evmAM572x.cfg

Add the following to the beginning of your configuration file

var Program = xdc.useModule('xdc.cfg.Program');

Comment out the Memory sections configuration as shown below

/* ================ Memory sections configuration ================ */
//Program.sectMap[".text"] = "EXT_RAM";
//Program.sectMap[".const"] = "EXT_RAM";
//Program.sectMap[".plt"] = "EXT_RAM";
/* Program.sectMap["BOARD_IO_DELAY_DATA"] = "OCMC_RAM1"; */
/* Program.sectMap["BOARD_IO_DELAY_CODE"] = "OCMC_RAM1"; */

Since we are no longer using a shared folder, make the following change

//var ipc_cfg = xdc.loadCapsule("../shared/ipc.cfg.xs");
var ipc_cfg = xdc.loadCapsule("../ipc.cfg.xs");

Comment out the following. We’ll be calling this function directly from main.

//BIOS.addUserStartupFunction('&IpcMgr_ipcStartup');

Increase the system stack size

//Program.stack = 0x1000;
Program.stack = 0x8000;

Comment out the entire TICK section

/* --------------------------- TICK --------------------------------------*/
// var Clock = xdc.useModule('ti.sysbios.knl.Clock');
// Clock.tickSource = Clock.TickSource_NULL;
// //Clock.tickSource = Clock.TickSource_USER;
// /* Configure BIOS clock source as GPTimer5 */
// //Clock.timerId = 0;
//
// var Timer = xdc.useModule('ti.sysbios.timers.dmtimer.Timer');
//
// /* Skip the Timer frequency verification check. Need to remove this later */
// Timer.checkFrequency = false;
//
// /* Match this to the SYS_CLK frequency sourcing the dmTimers.
//  * Not needed once the SYS/BIOS family settings is updated. */
// Timer.intFreq.hi = 0;
// Timer.intFreq.lo = 19200000;
//
// //var timerParams = new Timer.Params();
// //timerParams.period = Clock.tickPeriod;
// //timerParams.periodType = Timer.PeriodType_MICROSECS;
// /* Switch off Software Reset to make the below settings effective */
// //timerParams.tiocpCfg.softreset = 0x0;
// /* Smart-idle wake-up-capable mode */
// //timerParams.tiocpCfg.idlemode = 0x3;
// /* Wake-up generation for Overflow */
// //timerParams.twer.ovf_wup_ena = 0x1;
// //Timer.create(Clock.timerId, Clock.doTick, timerParams);
//
// var Idle = xdc.useModule('ti.sysbios.knl.Idle');
// var Deh = xdc.useModule('ti.deh.Deh');
//
// /* Must be placed before pwr mgmt */
// Idle.addFunc('&ti_deh_Deh_idleBegin');

Make configuration change to use custom resource table. Add to the end of the file.

/* Override the default resource table with my own */
var Resource = xdc.useModule('ti.ipc.remoteproc.Resource');
Resource.customTable = true;

• Edit main_led_blink.c

Add the following external declarations

extern Int ipc_main();
extern Void IpcMgr_ipcStartup(Void);

In main(), add a call to ipc_main() and IpcMgr_ipcStartup() just before BIOS_start()

ipc_main();

if (callIpcStartup) {
    IpcMgr_ipcStartup();
}

/* Start BIOS */
BIOS_start();
return (0);

Comment out the line that calls Board_init(boardCfg). This call is in the original example because it assumes TI-RTOS is running on the Arm but in our case here, we are running Linux and this call is destructive so we comment it out.

#if defined(EVM_K2E) || defined(EVM_C6678)
    boardCfg = BOARD_INIT_MODULE_CLOCK |
    BOARD_INIT_UART_STDIO;
#else
    boardCfg = BOARD_INIT_PINMUX_CONFIG |
    BOARD_INIT_MODULE_CLOCK |
    BOARD_INIT_UART_STDIO;
#endif
    //Board_init(boardCfg);

• Edit MainDsp1.c

The app now has it’s own main(), so rename this one and get rid of args

//Int main(Int argc, Char* argv[])
Int ipc_main()
{

No longer using args so comment these lines

//taskParams.arg0 = (UArg)argc;
//taskParams.arg1 = (UArg)argv;

BIOS_start() is done in the app main() so comment it out here

/* start scheduler, this never returns */
//BIOS_start();

Comment this out

//Log_print0(Diags_EXIT, "<-- main:");

• Edit rsc_table_vayu_dsp.c

Set this #define before it’s used to select PHYS_MEM_IPC_VRING value

#define VAYU_DSP_1

Add this extern declaration prior to the symbol being used

extern char ti_trace_SysMin_Module_State_0_outbuf__A;

• Edit Server.c

No longer have shared folder so change include path

/* local header files */
//#include "../shared/AppCommon.h"
#include "../AppCommon.h"

Download the Full CCS Project

GPIO_LedBlink_evmAM572x_c66xExampleProject_with_ipc.zip

Adding IPC to an existing TI RTOS application on the IPU

A common thing people want to do is take an existing IPU application that may be controlling serial or control interfaces and add IPC to it so that the firmware can be loaded from the ARM. This is common when migrating from a IPU only solution to a heterogeneous SoC with an MPUSS (ARM) and IPUSS. This is the focus of this section.

In order to describe this process, we need an example TI RTOS test case to work with. For this purpose, we’ll be using the UART_BasicExample_evmAM572x_m4ExampleProject example that’s part of the PDK (installed as part of the Processor SDK RTOS). This example uses TI RTOS and does serial IO using UART3 port on the AM572x GP EVM, it’s labeled Serial Debug on the EVM silkscreen.

There were several steps taken to make this whole process work, each of which will be described in following sections

1. Build and run the out-of-box UART M4 example on the EVM using Code Composer Studio (CCS)
2. Build and run the ex02_messageQ example from the IPC software bundle and turn it into a CCS project. Build it and modify the Linux startup code to use this new image. This is just a sanity check step to make sure we can build the IPC examples in CCS and have them run at boot up on the EVM.
3. In CCS, make a clone of the out-of-box UART M4 example and rename it to denote it’s the IPC version of the example. Then using the ex02_messageq example as a reference, add in the IPC pieces to the UART example code. Build from CCS then add it to the Linux firmware folder.

Running UART Read/Write PDK Example from CCS

Developers are required to run pdkProjectCreate script to generate this example as described in the Processor SDK RTOS wiki article.

For the UART M4 example run the script with the following arguments:

pdkProjectCreate.bat AM572x evmAM572x little uart m4

After you run the script, you can find the UART M4 example project at <SDK_INSTALL_PATH>\pdk_am57xx_1_0_4\packages\MyExampleProjects\UART_BasicExample_evmAM572x_m4ExampleProject.

Import the project in CCS and build the example. You can now connect to the EVM using an emulator and CCS using the instructions provided here: https://processors.wiki.ti.com/index.php/AM572x_GP_EVM_Hardware_Setup

Connect to the ARM core and make sure GEL runs multicore initialization and brings the IPUSS out of reset. Connect to IPU2 core0 and load and run the M4 UART example. When you run the code you should see the following log on the serial IO console:

uart driver and utils example test cases :
Enter 16 characters or press Esc
1234567890123456  <- user input
Data received is
1234567890123456  <- loopback from user input
uart driver and utils example test cases :
Enter 16 characters or press Esc

Build and Run ex02_messageq IPC example

Follow instructions described in Article Run IPC Linux Examples

Update Linux Kernel device tree to remove UART that will be controlled by M4

Linux kernel enables all SOC HW modules which are required for its configuration. Appropriate drivers configure required clocks and initialize HW registers. For all unused IPs clocks are not configured.

The uart3 node is disabled in kernel using device tree. Also this restricts kernel to put those IPs to sleep mode.

&uart3 {
    status = "disabled";
    ti,no-idle;
};

Add IPC to the UART Example

The first step is to clone our out-of-box UART example CCS project and rename it to denote it’s using IPC. The easiest way to do this is using CCS. Here are the steps...

• In the Edit perspective, go into your Project Explorer window and right click on your UART_BasicExample_evmAM572x_m4ExampleProject project and select copy from the pop-up menu. Maske sure the project is not is a closed state.
• Rick click in and empty area of the project explorer window and select past.
• A dialog box pops up, modify the name to denote it’s using IPC. A good name is UART_BasicExample_evmAM572x_m4ExampleProject_with_ipc.

This is the project we’ll be working with from here on. The next thing we want to do is select the proper RTSC platform and other components. To do this, follow these steps.

• Right click on the UART_BasicExample_evmAM572x_m4ExampleProject_with_ipc project and select Properties
• In the left hand pane, click on CCS General.
• On the right hand side, click on the RTSC tab
• For XDCtools version: select 3.xx.x.xx_core
• In the list of Products and Repositories, check the following...
  • IPC 3.xx.x.xx
  • SYS/BIOS 6.4x.x.xx
  • am57xx PDK x.x.x
• For Target, select ti.targets.arm.elf.M4
• For Platform, select ti.platforms.evmDRA7XX
• Once the platform is selected, edit its name buy hand and append :ipu2 to the end. After this it should be ti.platforms.evmDRA7XX:ipu2
• Go ahead and leave the Build-profile set to debug.
• Hit the OK button.

Now we want to copy configuration and source files from the ex02_messageq IPC example into our project. The IPC example is located at C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq. To copy files into your CCS project, you can simply select the files you want in Windows explorer then drag and drop them into your project in CCS.

Copy these files into your CCS project...

• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\shared\AppCommon.h
• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\shared\config.bld
• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\shared\ipc.cfg.xs

Now copy these files into your CCS project...

• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\ipu2\Ipu2.cfg
• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\ipu2\MainIpu2.c
• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\ipu2\Server.c
• C:\ti\ipc_3_xx_xx_xx\examples\DRA7XX_linux_elf\ex02_messageq\ipu2\Server.h

Finally, you will likely want to use a custom resource table so copy these files into your CCS project...

• C:\ti\ipc_3_xx_xx_xx\packages\ti\ipc\remoteproc\rsc_table_vayu_ipu.h
• C:\ti\ipc_3_xx_xx_xx\packages\ti\ipc\remoteproc\rsc_types.h

The rsc_table_vayu_dsp.h file defines an initialized structure so let’s make a .c source file.

• In your CCS project, rename rsc_table_vayu_ipu.h to rsc_table_vayu_ipu.c

Now we want to merge the IPC example configuration file with the LED blink example configuration file. Follow these steps...

• Open up Ipu2.cfg using a text editor (don’t open it using the GUI). Right click on it and select Open With -> XDCscript Editor
• We want to copy the entire contents into the clipboard. Select all and copy.
• Now just like above, open the uart_m4_evmAM572x.cfg config file in the text editor. Go to the very bottom and paste in the contents from the Ipu2.cfg file. Basically we’ve appended the contents of Ipu2.cfg into uart_m4_evmAM572x.cfg.

We’ve now added in all the necessary configuration and source files into our project. Don’t expect it to build at this point, we have to make edits first. These edits are listed below.

NOTE, you can download the full CCS project with source files to use as a reference.
See link towards the end of this section.

• Edit uart_m4_evmAM572x.cfg

Add the following to the beginning(at the top) of your configuration file

var Program = xdc.useModule('xdc.cfg.Program');

Since we are no longer using a shared folder, make the following change

//var ipc_cfg = xdc.loadCapsule("../shared/ipc.cfg.xs");
var ipc_cfg = xdc.loadCapsule("../ipc.cfg.xs");

Comment out the following. We’ll be calling this function directly from main.

//BIOS.addUserStartupFunction('&IpcMgr_ipcStartup');

Increase the system stack size

//Program.stack = 0x1000;
Program.stack = 0x8000;

Comment out the entire TICK section

/* --------------------------- TICK --------------------------------------*/
// var Clock = xdc.useModule('ti.sysbios.knl.Clock');
// Clock.tickSource = Clock.TickSource_NULL;
// //Clock.tickSource = Clock.TickSource_USER;
// /* Configure BIOS clock source as GPTimer5 */
// //Clock.timerId = 0;
//
// var Timer = xdc.useModule('ti.sysbios.timers.dmtimer.Timer');
//
// /* Skip the Timer frequency verification check. Need to remove this later */
// Timer.checkFrequency = false;
//
// /* Match this to the SYS_CLK frequency sourcing the dmTimers.
//  * Not needed once the SYS/BIOS family settings is updated. */
// Timer.intFreq.hi = 0;
// Timer.intFreq.lo = 19200000;
//
// //var timerParams = new Timer.Params();
// //timerParams.period = Clock.tickPeriod;
// //timerParams.periodType = Timer.PeriodType_MICROSECS;
// /* Switch off Software Reset to make the below settings effective */
// //timerParams.tiocpCfg.softreset = 0x0;
// /* Smart-idle wake-up-capable mode */
// //timerParams.tiocpCfg.idlemode = 0x3;
// /* Wake-up generation for Overflow */
// //timerParams.twer.ovf_wup_ena = 0x1;
// //Timer.create(Clock.timerId, Clock.doTick, timerParams);
//
// var Idle = xdc.useModule('ti.sysbios.knl.Idle');
// var Deh = xdc.useModule('ti.deh.Deh');
//
// /* Must be placed before pwr mgmt */
// Idle.addFunc('&ti_deh_Deh_idleBegin');

Make configuration change to use custom resource table. Add to the end of the file.

/* Override the default resource table with my own */
var Resource = xdc.useModule('ti.ipc.remoteproc.Resource');
Resource.customTable = true;

• Edit main_uart_example.c

Add the following external declarations

extern Int ipc_main();
extern Void IpcMgr_ipcStartup(Void);

In main(), add a call to ipc_main() and IpcMgr_ipcStartup() just before BIOS_start()

ipc_main();
if (callIpcStartup) {
   IpcMgr_ipcStartup();
 }
 /* Start BIOS */
 BIOS_start();
 return (0);

Comment out the line that calls Board_init(boardCfg). This call is in the original example because it assumes TI-RTOS is running on the Arm but in our case here, we are running Linux and this call is destructive so we comment it out. The board init call does all pinmux configuration, module clock and UART peripheral initialization.

In order to run the UART Example on M4, you need to disable the UART in the Linux DTB file and interact with the Linux kernel using Telnet (This will be described later in the article). Since Linux will be running uboot performs the pinmux configuration but clock and UART Stdio setup needs to be performed by the M4.

Original code

#if defined(EVM_K2E) || defined(EVM_C6678)
    boardCfg = BOARD_INIT_MODULE_CLOCK | BOARD_INIT_UART_STDIO;
#else
    boardCfg = BOARD_INIT_PINMUX_CONFIG | BOARD_INIT_MODULE_CLOCK | BOARD_INIT_UART_STDIO;
#endif
    Board_init(boardCfg);

Modified Code :

boardCfg = BOARD_INIT_UART_STDIO;

Board_init(boardCfg);

We are not done yet as we still need to configure turn the clock control on for the UART without impacting the other clocks. We can do that by adding the following code before Board_init API call:

CSL_l4per_cm_core_componentRegs *l4PerCmReg =
    (CSL_l4per_cm_core_componentRegs *)CSL_MPU_L4PER_CM_CORE_REGS;
CSL_FINST(l4PerCmReg->CM_L4PER_UART3_CLKCTRL_REG,
    L4PER_CM_CORE_COMPONENT_CM_L4PER_UART3_CLKCTRL_REG_MODULEMODE, ENABLE);
while(CSL_L4PER_CM_CORE_COMPONENT_CM_L4PER_UART3_CLKCTRL_REG_IDLEST_FUNC !=
   CSL_FEXT(l4PerCmReg->CM_L4PER_UART3_CLKCTRL_REG,
    L4PER_CM_CORE_COMPONENT_CM_L4PER_UART3_CLKCTRL_REG_IDLEST));

• Edit MainIpu2.c

The app now has it’s own main(), so rename this one and get rid of args

//Int main(Int argc, Char* argv[])
Int ipc_main()
{

No longer using args so comment these lines

//taskParams.arg0 = (UArg)argc;
//taskParams.arg1 = (UArg)argv;

BIOS_start() is done in the app main() so comment it out here

/* start scheduler, this never returns */
//BIOS_start();

Comment this out

//Log_print0(Diags_EXIT, "<-- main:");

• Edit rsc_table_vayu_ipu.c

Set this #define before it’s used to select PHYS_MEM_IPC_VRING value

#define VAYU_IPU_2

Add this extern declaration prior to the symbol being used

extern char ti_trace_SysMin_Module_State_0_outbuf__A;

• Edit Server.c

No longer have shared folder so change include path

/* local header files */
//#include "../shared/AppCommon.h"
#include "../AppCommon.h"

Handling AMMU (L1 Unicache MMU) and L2 MMU

There are two MMUs inside each of the IPU1, and IPU2 subsystems. The L1 MMU is referred to as IPU_UNICACHE_MMU or AMMU and L2 MMU. The description of how this is configured in IPC-remoteproc has been described in section Changing_Cortex_M4_IPU_Memory_Map. IPC handling of L1 and L2 MMU is different from how the PDK driver examples setup the memory access using these MMUs which the users need to manage when integrating the components. This difference is highlighted below:

• PDK examples use addresses (0x4X000000) to peripheral registers and use following MMU setting
  • L2 MMU uses default 1:1 Mapping
  • AMMU configuration translates physical 0x4X000000 access to logical 0x4X000000
• IPC+ Remote Proc ARM+M4 requires IPU to use logical address (0x6X000000) and uses following MMU setting
  • L2 MMU is configured such that MMU translates 0x6X000000 access to addresss 0x4X000000
  • AMMU is configured for 1:1 mapping 0x6X000000 and 0x6X000000

Therefore after integrating IPC with PDK drivers, it is recommended that the alias addresses are used to access peripherals and PRCM registers. This requires changes to the addresses used by PDK drivers and in application code.

The following changes were then made to the IPU application source code:

Add UART_soc.c file to the project and modify the base addresses for all IPU UART register instance in the UART_HwAttrs to use alias addresses:

#ifdef _TMS320C6X
    CSL_DSP_UART3_REGS,
    OSAL_REGINT_INTVEC_EVENT_COMBINER,
#elif defined(__ARM_ARCH_7A__)
    CSL_MPU_UART3_REGS,
    106,
#else
    (CSL_IPU_UART3_REGS + 0x20000000),    //Base Addr = 0x48000000 + 0x20000000 = 0x68000000
    45,
#endif

Adding custom SOC configuration also means that you should use the generic UART driver instead of driver with built in SOC setup. To do this comment the following line in .cfg:

var Uart              = xdc.loadPackage('ti.drv.uart');
//Uart.Settings.socType = socType;

There is also an instance in the application code where we added pointer to PRCM registers that need to be changed as follows.

 CSL_l4per_cm_core_componentRegs *l4PerCmReg =
(CSL_l4per_cm_core_componentRegs \*) 0x6a009700; //CSL_MPU_L4PER_CM_CORE_REGS;

Now, you are ready to build the firmware. After the .out is built, change the extension to .xem4 and copy it over to the location in the filesystem that is used to load M4 firmware.

Download the Full CCS Project

UART_BasicExample_evmAM572x_m4ExampleProject_with_ipc.zip

3.6.4. IPC for AM65xx¶

Introduction

The AM65xx device has an MCU subsystem in addition to the Cortex-A53 cores. The MCU subsystem consists of 2 Cortex-R5F cores which can work as seperate cores or in lock-step mode.

This article is geared toward AM65xx users that are running Linux on the Cortex A53 core. The goal is to help users understand how to establish communication with the R5F cores.

There are many facets to this task: building, loading, debugging, memory sharing, etc. This article intends to take incremental steps toward understanding all of those pieces.

Software Dependencies to Get Started

Prerequisites

• Processor SDK Linux for AM65xx (Version 5.1 or newer needed)
• Processor SDK RTOS for AM65xx
• Code Composer Studio (choose version as specified on Proc SDK download page)

For reference within the context of this wiki page, the Linux SDK is installed at the following location:

/mnt/data/user/ti-processor-sdk-linux-am65xx-evm-xx.xx.xx.xx
├── bin
├── board-support
├── docs
├── example-applications
├── filesystem
├── ipc-build.txt
├── linux-devkit
├── Makefile
├── Rules.make
└── setup.sh

The RTOS SDK is installed at:

/mnt/data/user/my_custom_install_sdk_rtos_am65xx_xx.xx
├── bios_6_xx_xx_xx
├── cg_xml
├── ctoolslib_x_x_x_x
├── framework_components_x_xx_xx_xx
├── gcc-linaro-<version>-x86_64_aarch64-elf
├── ipc_3_xx_xx_xx
├── ndk_3_xx_xx_xx
├── ns_2_xx_xx_xx
├── pdk_am65xx_x_x_x
├── processor_sdk_rtos_am65xx_x_xx_xx_xx
├── uia_2_xx_xx_xx
├── xdais_7_xx_xx_xx
├── xdctools_3_xx_xx_xx

Typical Boot Flow on AM65xx for ARM Linux users

AM65xx SOC’s have multiple processor cores - Cortex A53, ARM R5F cores. The A53 typically runs a HLOS like Linux/Android and the remote cores (R5Fs) run TI-RTOS. In the normal operation, boot loader(U-Boot/SPL) boots and loads the A53 with the HLOS. The A53 boots the R5 cores.

In this sequence, the interval between the Power on Reset and the remote cores (i.e. the R5Fs) executing is dependent on the HLOS initialization time.

Getting Started with IPC Linux Examples

The figure below illustrates how remoteproc/rpmsg driver from ARM Linux kernel communicates with IPC driver on slave processor (e.g. R5F) running RTOS.

In order to setup IPC on slave cores, we provide some pre-built examples in IPC package that can be run from ARM Linux. The subsequent sections describe how to build and run this examples and use that as a starting point for this effort.

Building the Bundled IPC Examples

The instructions to build IPC examples found under ipc_3_xx_xx_xx/examples/AM65XX_linux_elf have been provided in the Processor SDK IPC Quick Start Guide.

Let’s focus on one example in particular, ex02_messageq, which is located at <rtos-sdk-install-dir>/ipc_3_xx_xx_xx/examples/AM65XX_linux_elf/ex02_messageq. Here are the key files that you should see after a successful build:

├── r5f-0
│   └── bin
│       ├── debug
│       │   └── server_r5f-0.xer5f
│       └── release
│       │   └── server_r5f-0.xer5f
├── r5f-1
│   └── bin
│       ├── debug
│       │   └── server_r5f-1.xer5f
│       └── release
│       │   └── server_r5f-1.xer5f
├── host
│       ├── debug
│       │   └── app_host
│       └── release
│           └── app_host

Running the Bundled IPC Examples

On the target, let’s create a directory called ipc-starter:

root@am65xx-evm:~# mkdir -p /home/root/ipc-starter
root@am65xx-evm:~# cd /home/root/ipc-starter/

You will need to copy the ex02_messageq directory of your host PC to that directory on the target (through SD card, NFS export, SCP, etc.). You can copy the entire directory, though we’re primarily interested in these files:

• r5f-0/bin/debug/server_r5f-0.xer5f
• r5f-1/bin/debug/server_r5f-1.xer5f
• host/bin/debug/app_host

The remoteproc driver is hard-coded to look for specific files when loading the R5F cores. Here are the files it looks for:

• /lib/firmware/am65x-mcu-r5f0-fw

These are generally a soft link to the intended executable. So for example, let’s update the r5f0 executable on the target:

root@am65xx-evm:~# cd /lib/firmware/
root@am65xx-evm:/lib/firmware# ln -sf /home/root/ipc-starter/ex02_messageq/r5f-0/bin/debug/server_r5f-0.xer5f am65x-mcu-r5f0-fw

To reload R5F0 with this new executable, we perform the following steps:

First identify the remotproc node associated with R5F0. This can be done by:

root@am65xx-evm:/lib/firmware# grep -Isr r5f /sys/kernel/debug/remoteproc/

This will display for example:

/sys/kernel/debug/remoteproc/remoteproc8/resource_table:  Name trace:r5f0
/sys/kernel/debug/remoteproc/remoteproc8/name:41000000.r5f

then remoteproc8 is the node for the r5f core. ( Note the remoteprocx can change to for example remoteproc4):

root@am65xx-evm:~# echo stop > /sys/class/remoteproc/remoteproc4/state
[ 6663.636529] remoteproc remoteproc4: stopped remote processor 41000000.r5f

root@am65xx-evm:~# echo start > /sys/class/remoteproc/remoteproc4/state [ 6767.681165] remoteproc remoteproc4: powering up 41000000.r5f
[ 6767.803683] remoteproc remoteproc4: Booting fw image am65x-mcu-r5f0-fw, size 3590160
[ 6767.812558] platform 41000000.r5f: booting R5F core using boot addr = 0x0
[ 6767.821345] virtio_rpmsg_bus virtio0: rpmsg host is online
[ 6767.827147] remoteproc remoteproc4: registered virtio0 (type 7)
[ 6767.834776] remoteproc remoteproc4: remote processor 41000000.r5f is now up
root@am65xx-evm:~# [ 6767.848838] virtio_rpmsg_bus virtio0: creating channel rpmsg-proto addr 0x3d

More info related to loading firmware to the various cores can be found here.

Finally, we can run the example on R5 core:

root@am65xx-evm:~# ./app_host R5F-0
--> main:
--> Main_main:
--> App_create:
App_create: Host is ready
<-- App_create:
--> App_exec:
App_exec: sending message 1
App_exec: sending message 2
App_exec: sending message 3
App_exec: message received, sending message 4
App_exec: message received, sending message 5
App_exec: message received, sending message 6
App_exec: message received, sending message 7
App_exec: message received, sending message 8
App_exec: message received, sending message 9
App_exec: message received, sending message 10
App_exec: message received, sending message 11
App_exec: message received, sending message 12
App_exec: message received, sending message 13
App_exec: message received, sending message 14
App_exec: message received, sending message 15
App_exec: message received
App_exec: message received
App_exec: message received
<-- App_exec: 0
--> App_delete:
<-- App_delete:
<-- Main_main:
<-- main:
root@am65xx-evm:~#

Understanding the Memory Map

Overall Linux Memory Map

root@am65xx-evm:~# cat /proc/iomem
[snip...]
    80000000-9affffff : System RAM
    80080000-80b2ffff : Kernel code
    80bb0000-80d9ffff : Kernel data
    9c800000-9e7fffff : System RAM
    a0000000-ffffffff : System RAM
    400000000-4ffffffff : /soc0/fss@47000000/ospi@47040000
    880000000-8ffffffff : System RAM

DMA memory Carveouts

root@am65xx-evm:~# dmesg | grep  "Reserved memory"
[    0.000000] Reserved memory: created DMA memory pool at 0x000000009b000000, size 16 MiB
[    0.000000] Reserved memory: created DMA memory pool at 0x000000009c000000, size 8 MiB

From the output above, we can derive the location and size of each DMA carveout:

For details on how to adjust the sizes and locations of the R5F Pool carveouts, please see the corresponding section for changing the R5F memory map.

Changing the R5F Memory Map

Slave Physical Addresses

The physical location where the R5F code/data will actually reside is defined by the DMA carveout. To change this location, you must change the definition of the carveout. The R5F carveouts are defined in the Linux dts file. For example for the AM65xx EVM:

reserved-memory {
                #address-cells = <2>;
                #size-cells = <2>;
                ranges;

                r5f1_memory_region: r5f1-memory@9b000000 {
                        compatible = "shared-dma-pool";
                        reg = <0 0x9b000000 0 0x1000000>;
                        no-map;
                };

                r5f0_memory_region: r5f0-memory@9c000000 {
                        compatible = "shared-dma-pool";
                        reg = <0 0x9c000000 0 0x800000>;
                        no-map;
                };

                secure_ddr: secure_ddr@9e800000 {
                        reg = <0 0x9e800000 0 0x01800000>; /* for OP-TEE */
                        alignment = <0x1000>;
                        no-map;
                };
        };

You are able to change both the size and location. Be careful not to overlap any other carveouts!

Additionally, when you change the carveout location, there is a corresponding change that must be made to the resource table. For starters, if you’re making a memory change you will need a custom resource table. The resource table is a large structure that is the “bridge” between physical memory and virtual memory. There is detailed information available in the article IPC Resource customTable.

Once you’ve created your custom resource table, you must update the address of PHYS_MEM_IPC_VRING to be the same base address as your corresponding CMA.

#define R5F_MEM_TEXT            0x9C200000
#define R5F_MEM_DATA            0x9C300000

#define R5F_MEM_IPC_DATA        0x9C100000
#define R5F_MEM_IPC_VRING       0x9C000000
#define R5F_MEM_RPMSG_VRING0    0x9C000000
#define R5F_MEM_RPMSG_VRING1    0x9C010000
#define R5F_MEM_VRING_BUFS0     0x9C040000
#define R5F_MEM_VRING_BUFS1     0x9C080000

R5 Virtual Addresses

These addresses are the ones seen by the MCU subsystem, i.e. these will be the addresses in your linker command files, etc.

You must ensure that the sizes of your sections are consistent with the corresponding definitions in the resource table. You should create your own resource table in order to modify the memory map. This is describe in the wiki page IPC Resource customTable. You can look at an existing resource table inside IPC:

ipc/packages/ti/ipc/remoteproc/rsc_table_am65xx_r5f.h

{
     TYPE_CARVEOUT,
     R5F_MEM_IPC_DATA, 0,
     R5F_MEM_IPC_DATA_SIZE, 0, 0, "R5F_MEM_IPC_DATA",
 },

 {
     TYPE_CARVEOUT,
     R5F_MEM_TEXT, 0,
     R5F_MEM_TEXT_SIZE, 0, 0, "R5F_MEM_TEXT",
 },

 {
     TYPE_CARVEOUT,
     R5F_MEM_DATA, 0,
     R5F_MEM_DATA_SIZE, 0, 0, "R5F_MEM_DATA",
 },

 {
     TYPE_TRACE, TRACEBUFADDR, TRACEBUFSIZE, 0, "trace:r5f0",
 },

Let’s have a look at some of these to understand them better. For example:

{
    TYPE_CARVEOUT,
    DSP_MEM_TEXT, 0,
    DSP_MEM_TEXT_SIZE, 0, 0, "DSP_MEM_TEXT",
},

Key points to note are:

1. The “TYPE_CARVEOUT” indicates that the physical memory backing this entry will come from the associated reserved pool.
2. DSP_MEM_TEXT is a #define earlier in the code providing the address for the code section. It is 0x9C200000 by default. This must correspond to a section from your DSP linker command file, i.e. EXT_CODE (or whatever name you choose to give it) must be linked to the same address.
3. DSP_MEM_TEXT_SIZE is the size of the text section. The actual amount of linked code in the corresponding section of your executable must be less than or equal to this size.

Let’s take another:

{
    TYPE_TRACE, TRACEBUFADDR, TRACEBUFSIZE, 0, "trace:r5f0",
},

Key points are:

1. The “TYPE_TRACE” indicates this is for trace info.
2. The TRACEBUFADDR is defined earlier in the file as &ti_trace_SysMin_Module_State_0_outbuf__A. That corresponds to the symbol used in TI-RTOS for the trace buffer.
3. The TRACEBUFSIZE is the size of the Trace section The corresponding size in the cfg file should be the same (or less). It looks like this: SysMin.bufSize  = 0x8000;

3.6.5. Multiple Ways of ARM-DSP Communication¶

OpenCL

OpenCL is a framework for writing programs that execute across heterogeneous systems, and for expressing programs where parallel computation is dispatched across heterogeneous devices. It is an open, royalty-free standard managed by Khronos consortium. On a heterogeneous SoC, OpenCL views one of the programmable cores as a host and the other cores as devices. The application running on the host (i.e. the host program) manages execution of code (kernels) on the device and is also responsible for making data available to the device. A device consists of one or more compute units. On the ARM and DSP SoCs, each C66x DSP is a compute unit. The OpenCL runtime consists of two components: (1) An API for the host program to create and submit kernels for execution and (2) A cross-platform language for expressing kernels – OpenCL C – which is based on C99 C with some additions and restrictions OpenCL supports both data parallel and task parallel programming paradigms. Data parallel execution parallelizes the execution across compute units on a device. Task parallel execution enables asynchronous dispatch of tasks to each compute unit. For more info, please refer to OpenCL User’s Guide

Use Cases

• Offload computation from ARM running Linux or RTOS to the DSPs

Examples

Please see OpenCL examples

Benefits

• Easy porting between devices
• No need to understand memory architecture
• No need to worry about MPAX and MMU
• No need to worry about coherency
• No need to build/configure/use IPC between ARM and DSP
• No need to be an expert in DSP code, architecture, or optimization

Drawbacks

• Don’t have control on system memory layout, etc. to handle optimize DSP code

DCE (Distributed Codec Engine)

DCE Framework provides an easy way for users to write applications on devices, such as AM57xx, having hardware accelerators for image and video. It eanbles and provides remote access to hardware acceleration for audio and video encoding and decoding on the slave cores. The ARM user space GStreamer based multimedia application uses GStreamer library to load and interface with TI GStreamer plugin which handles all the details specific to use of the hardware accelerator. The plugin interfaces libdce module that provides the ARM user space API. Libdce uses RPMSG framework on the ARM which communicates to the counterpart on the slave core. On the slave core, it uses Codec engine and Frame Component for the video/image codec processing on IVA.

Overview of the Multimedia Software Stack using DCE AM57xx as an example has the following accelerators

• Image and Video Accelerator (IVA)
• Video Processing Engine (VPE)
• C66x DSP cores for offloading certain image/video and/or voice/audio processing

Users can leverate open source elements that provide functionality such as AVI stream demuxing, and audio codec, etc. These along with the ARM based GStreamer plugins in TI’s Processor Linux SDK provide the abstracts for the accelerator offload.

In AM57xx, the hardware accelerators are capable of the following

• IVA for multimedia enconding and decoding
  • Video Decode: H264, MPEG4, MPEG2, and VC1
  • video Encode: H264, and MPEG4
  • Image Decode: MJPEG
• VGE for video operations such as scaling, color space conversion, and deinterlacing of the following formats:
  • Supported Input formats: NV12, YUYV, UYVY
  • Supported Output formats: NV12, YUYV, UYVY, RGB24, ARGB24, and ABGR24
• DSP for offloading signal processing
  • Sample Image Processing Kernels integrated in the DSP gstreamer plugin: Median2x2, Median3x3, Sobel3x3, Conv5x5, Canny

For more info, please refer to the DCE Developer’s Guide or DCE for Multimedia

Use Cases

• audio/video or proprietary codecs processing offload to slave core

Examples

• Please see sample application

Benefits

• Accelerated multimedia codec processing
• Simplifies the development of multimedia application when interfacing with Gstreamer and TI Gstreamer plugin

Drawbacks

• Not suitable for non-codec algorithm
• Need work to add new codec algorithm
• Need knowledge of DSP programming

Big Data IPC

Big Data is a special use case of TI IPC implementation for High Performance Computing applications and other Data intensive applications which often require passing of big data buffers between the multi-core processors in an SoC. The Big Data IPC provides a high level abstraction to take care of address translation and Cache sync on the big data buffers

Use Cases

• Message/Data exchange for size greater than 512 bytes between ARM and DSP

Examples

• Please see Big Data IPC example

Benefits

• Capable of handling data greater than 512 bytes

Drawbacks

• Need knowledge of DSP memory architecture
• Need knowledge of DSP configuration and programming
• TI proprietary API

IPC

Inter-Processor Communication (IPC) is a set of modules designed to faciliate inter-process communication. The communication includes message passing, streams, and linked lists. The modules provides services and functions which can be used for communication between ARM and DSP processors in a multi-processor environment.

• IPC Module initialized the various subsystems of IPC and synchronizes multiple processors.
• MessageQ Module supports the structured sending and receiving of variable length messages.
• ListMP Module is a linked-list based module designed to provide a mean of communication between different processors. It uses shared memory to provide a way for multiple processors to share, pass or store data buffers, messages,

or state information.

• HeapMP Module provides 3 types of memory management, fixed-size buffers, multiple different fixed-size buffers, and variable-size buffers.
• GateMP Module enforces both local and remote context protection through its instance.
• NOtify Module manages the multiplexing/demultiplexing of software interrupts over hardware interrupts.
• SharedRegion Module is designed to be used in a multi-processor environment where there are memory regions that are shared and accessed across different processors.
• List Module provides support for creating doubly-linked lists of objects
• MultiProc Module centralizes processor ID management into one module in a multi-processor environment.
• NameServer Module manages local name/value pairs which enables an application and other modules to sotre and retrieve values based on a name.

User Cases

• Message/Data exchange between ARM and DSP

Examples

• Please see IPC Examples

Benefits

• suitable for those who are familiar with DSP programming
• DSP code optimization

Drawbacks

• Need knowledge of DSP memory architecture
• Need knowledge of DSP configuration and programming
• message size is limited to 512 bytes
• TI proprietary API

Pros and Cons

Decision Making

The following simple flow chart is provided as a reference when making decision on which methods to use for ARM/DSP communication. Hardware capability also need to be considered in the decision making process, such as if Image and Video Accelerator exists when using DCE.