ipipsu Documentation

This section explains the implementation of IPIPSU driver. Inter Processor Interrupt (IPI) is used for communication between different processors on ZynqMP SoC. Each IPI register set has Trigger, Status and Observation registers for communication between processors. Each IPI path has a 32 byte buffer associated with it and these buffers are located in the XPPU RAM.

This driver supports the following operations:

• Trigger IPIs to CPUs on the SoC
• Write and Read Message buffers
• Read the status of Observation Register to get status of Triggered IPI
• Enable/Disable IPIs from selected Masters
• Read the Status register to get the source of an incoming IPI

Initialization & Configuration

The XIpiPsu_Config structure is used by the driver to configure itself. Fields inside this structure are properties of XIpiPsu based on its hardware build.

To support multiple runtime loading and initialization strategies employed by various operating systems, the driver instance can be initialized in the following way:

• XIpiPsu_CfgInitialize(InstancePtr, CfgPtr, EffectiveAddr) - Uses a configuration structure provided by the caller. If running in a system with address translation, the parameter EffectiveAddr should be the virtual address.

The config data for the driver is loaded and is based on the HW build. The XIpiPsu_Config data structure contains all the data related to the IPI driver instance and also the available Target CPUs.

Sending an IPI

The following steps can be followed to send an IPI:

• Write the Message into Message Buffer using XIpiPsu_WriteMessage()
• Trigger IPI using XIpiPsu_TriggerIpi()
• Wait for Ack using XIpiPsu_PollForAck()
• Read response using XIpiPsu_ReadMessage()

Note

XIpiPsu_GetObsStatus() before sending an IPI to ensure that the previous IPI was serviced by the target

Receiving an IPI

To receive an IPI, the following sequence can be followed:

• Register an interrupt handler for the IPIs interrupt ID
• Enable the required sources using XIpiPsu_InterruptEnable()
• In the interrupt handler, Check for source using XIpiPsu_GetInterruptStatus
• Read the message form source using XIpiPsu_ReadMessage()
• Write the response using XIpiPsu_WriteMessage()
• Ack the IPI using XIpiPsu_ClearInterruptStatus()

Note

XIpiPsu_Reset can be used at startup to clear the status and disable all sources

 MODIFICATION HISTORY:

 Ver  Who Date     Changes



 2.2  ms  01/23/17 Modified xil_printf statement in main function for all
                    examples to ensure that "Successfully ran" and "Failed"
                    strings are available in all examples. This is a fix
                    for CR-965028.
        kvn 02/17/17  Add support for updating ConfigTable at run time
      ms  03/17/17  Added readme.txt file in examples folder for doxygen
                    generation.
 2.3  ms  04/11/17  Modified tcl file to add suffix U for all macro
                    definitions of ipipsu in xparameters.h
      ms  03/28/17  Add index.html to provide support for importing
                    examples in SDK.
 2.5  sdd 12/17/18  Add the cpp extern macro.
 2.6  sdd 04/09/20  Restructure the code for modularity and readability
                      Added file  xipipsu_buf.c and xipipsu_buf.h as part of it.
 2.7  sdd 09/03/20  Makefile update for parallel execution.
 2.8  nsk 12/14/20  Modified the driver tcl to not to use the instance names.
 2.8  nsk 01/19/21  Updated the driver tcl to use IP_NAME for IPIs mapped.
 2.9  ma  02/12/21  Added IPI CRC functionality
        sdd 02/17/21 Fixed doxygen warnings.
        sdd 03/10/21 Fixed misrac warnings.
                     Fixed doxygen warnings.
 2.11 sdd 11/17/21 Updated tcl to check for microblaze processors
 2.14 adk 04/14/23 Added support for system device-tree flow.
 2.14 adk 05/22/23 Added IPI Mask's for referring to processor IPI Targets
                     in system device-tree flow.
 2.14 sd 07/27/23  Update the target count.