4.9. IPC¶

4.9.6.1. Dependency of External PDK Components¶

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

4.9.6.2. 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.

4.9.6.3. Available Core names¶

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)

4.9.6.4. Expected Output¶

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

PDK_INSTALL_PATH/packages/ti/binary/<test_name>/bin/j721e_evm/

4.9.7.1. Example Details¶

4.9.7.2. 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.

   • Refer the J721E EVM CCS Setup Documentation section for details of setting up the CCS target configuration and loading system firmware.

   • 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_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_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_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

4.9.7.3. 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

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

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

4.9.8.2. 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 for mcu_r5fss0_core0 will come from the 0xa0000000 entry.

Note that this address is specific to the Linux<->remote core VRING, and is different from the address provided to the Virtio module in the remote core firmware in the call to Ipc_initVirtIO.

4.9.8.3. 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/.