4.7. IPC¶

4.7.6.1. Dependency of External PDK Components¶

IPCLLD does not access any hardware diretly. It uses the PDK/csl component to configure Mailbox registers. It uses sciclient to set/release Mailbox interrupt. Also it uses PDK/osal to configure OS-related steps like Semaphore etc.

• pdk/csl : Configures Mailbox registers
• pdk/sciclient : Set Mailbox interrupts
• pdk/osal : To register for HWI and other kernel stuffs.

4.7.6.2. Command to build IPCLLD¶

The build can be done either from the IPCLLD’s path in the PDK packages, or from the PDK build folder. For either method, the following environment variables must be defined, or supplied with the build command (if they are different from the defaults of the SDK installation):

• SDK_INSTALL_PATH: Installation root for sdk
• TOOLS_INSTALL_PATH: where all the tool chains are installed, if different from SDK_INSTALL_PATH
• PDK_INSTALL_PATH: Installtion root for pdk

The following build instructions are for Linux. For Windows build, please replace “make” with “gmake”.

Method 1:

These libraries and examples are built from the IPCLLD’s path in the PDK packages:

PDK_INSTALL_DIR/packages/ti/drv/ipc

Method 2:

If building from the PDK build folder, then use following steps to build

Go to PDK_INSTALL_DIR/packages/ti/build

See Example Details for list of supported examples.

4.7.6.3. Available Core names¶

AM65XX:

• mpu1_0 (A53)
• mcu1_0 (r5f0_0)
• mcu1_1 (r5f0_1)

J721E:

• mpu1_0 (A72)
• mcu1_0 (mcu-r5f0_0)
• mcu1_1 (mcu-r5f0_1)
• mcu2_0 (main-r5f0_0)
• mcu2_1 (main-r5f0_1)
• mcu3_0 (main-r5f1_0)
• mcu3_1 (main-r5f1_1)
• c66xdsp_1 (c66x_0)
• c66xdsp_2 (c66x_1)
• c7x_1 (c71x_0)

4.7.6.4. Expected Output¶

The built example binaries can be found in the PDK’s binary folder:

PDK_INSTALL_PATH/packages/ti/binary/<test_name>/bin/<board_name>/

4.7.7.1. Example Details¶

• ipc_echo_test: This is most generic example application where mpu1_0 is running Linux, and all other cores running bios. All cores talk to each other bi-diectionally. It is send ping message and remote end responds pong message. There are 10000 ping/pong messages exchanged between each core-pair.
• ex01_bios_2core_echo_test: This is the simplistic ping/pong application between any two cores running BIOS
• ex02_bios_multicore_echo_test: All cores running BIOS, many-to-many communication, each sending ping/pong with each other. mpu1_0 is also running BIOS.
• ex03_linux_bios_2core_echo_test: This is simplistic ping/pong application where mpu1_0 running Linux and any other core is running Bios.
• ex04_linux_baremetal_2core_echo_test: AM65xx only. This is a ping/pong application where mpu1_0 is running Linux and the other core is baremetal (no OS).

4.7.7.2. Loading Remote Firmware¶

Remote firmware can be loading using CCS or using uBoot SPL.

1. Loading using CCS :

   Sciclient module contains default system firmware and CCS script to load the system firmware. The load scripts should be modified to reflect the correct full-path of the script location. Once the script is updated,

   • start TI CCS 9.1 or newer

   • open CCS script console using menu View –> Scripting Console

   • Run the script using following command (example below is for J721E, use the appropriate one for your target)

     • loadJSFile(“PDK_INSTALL_DIR/packages/ti/drv/sciclient/tools/ccsLoadDmsc/j721e/launch.js”)

     

   • Connect the cores

     • select the core
     • right-click and connect

   • Load the remote binaries

     • Menu Run –> Load Program

   • Run the cores.

   • After running the cores, the sample output should look something like below.

     

2. Loading using SPL/uBoot

Run following steps to configure remote firmware for SPL loading with HLOS running on MPU

1. Copy the remote firmware to rootfs at /lib/firmware/pdk-ipc folder
2. cd /lib/firmware
3. Remove old soft link for remote cores
   • rm j7*
4. Create new soft links
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_c66xdsp_1_release.xe66 j7-c66_0-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_c66xdsp_2_release.xe66 j7-c66_1-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_c7x_1_release.xe71 j7-c71_0-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_mcu2_0_release.xer5f j7-main-r5f0_0-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_mcu2_1_release.xer5f j7-main-r5f0_1-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_mcu3_0_release.xer5f j7-main-r5f1_0-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_mcu3_1_release.xer5f j7-main-r5f1_1-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_testb_mcu1_0_release.xer5f j7-mcu-r5f0_0-fw
   • ln -s /lib/firmware/pdk-ipc/ipc_echo_test_mcu1_1_release.xer5f j7-mcu-r5f0_1-fw
5. sync : write the changes to filesystem
6. Reboot the system

4.7.7.3. Running the Echo Tests¶

In this section ipc_echo_test is used to demonstrate, but same instructions apply to other examples that have Linux on MPU, though test output may be slightly different.

1. Login as root

2. Start sample app as below

   • modprobe rpmsg_client_sample count=5
   

3. After running the sample app, it should display something below

4.7.8.1. Typical Data-Flow in IPCLLD communication between two cores¶

Following picture illustrates the data flow between two cores using mailbox IP as transport.

4.7.8.2. Resource Table¶

For applications that will use Linux IPC, a resource table is required. Example resource tables can be found in the IPC examples:

The resource table must have at least one entry, the VDEV entry, to define the the vrings used for IPC communication with Linux. Optionally, the resource table can also have a TRACE entry which defines the location of the remote core trace buffer.

The VDEV entry specifies the address as RPMSG_VRING_ADDR_ANY, meaning that the address will be allocated by the Linux driver during loading. The allocation is made from the first memory-region specified in the dts file for the remote core. For example, if the dts entry for mcu_r5fss0_core0 is

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

    mcu_r5fss0_core0_dma_memory_region: r5f-dma-memory@a0000000 {
            compatible = "shared-dma-pool";
            reg = <0 0xa0000000 0 0x100000>;
            no-map;
    };

    mcu_r5fss0_core0_memory_region: r5f-memory@a0100000 {
            compatible = "shared-dma-pool";
            reg = <0 0xa0100000 0 0xf00000>;
            no-map;
    };
}

then the allocation for the vrings will come from the 0xa0000000 entry.

4.7.8.3. Memory Considerations¶

As mentioned in IPCLLD Design Details, the Ring Buffer memory must be reserved system-wide. In addition, the Ring Buffer memory should be configured as non-cached on all cores using IPCLLD. For examples of configurations for Ring Buffer memory, refer to the examples in pdk/packages/ti/drv/ipc/examples/.