Nios® V Processor: Lockstep Implementation

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ID 833274
Date 10/07/2024
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Document Table of Contents
Document Table of Contents x
1. About the Nios® V Processor Lockstep 2. Overview 3. Controlling the Nios® V Processor Lockstep 4. Programming Model 5. Signals, Interfaces, and Build Parameters 6. Using Nios® V Processor Lock Step A. Document Revision History for the Nios® V Processor: Lockstep Implementation B. Appendix
1. About the Nios® V Processor Lockstep x
1.1. Nios® V Processor Lockstep Features
2. Overview x
2.1. Introduction 2.2. Main Principles 2.3. Operating Modes 2.4. Resets 2.5. LOGS Information
2.2. Main Principles x
2.2.1. System Phases 2.2.2. System States 2.2.3. Safety Mechanisms
2.2.2. System States x
2.2.2.1. Transitioning between System States
2.2.3. Safety Mechanisms x
2.2.3.1. Self-Checking Comparator 2.2.3.2. Timeout Timer 2.2.3.3. Enable Counters 2.2.3.4. Specialized Safety Mechanism
2.3. Operating Modes x
2.3.1. NORMAL and SILENT Modes
2.4. Resets x
2.4.1. Resetting CORE 2.4.2. Resetting OPTIONS 2.4.3. Resetting LOGS 2.4.4. Resetting Time Diversity Register
2.5. LOGS Information x
2.5.1. ALARMS 2.5.2. CONTEXT 2.5.3. STATISTICS 2.5.4. Reset LOGS
2.5.1. ALARMS x
2.5.1.1. Configuring Alarm Severity
3. Controlling the Nios® V Processor Lockstep x
3.1. Configuration Interface 3.2. fRNET Interface 3.3. Controlling the Elective Features
3.3. Controlling the Elective Features x
3.3.1. Applying Timeout and Comparator Blind Window 3.3.2. Injecting Fault 3.3.3. Downloading the CPU Software 3.3.4. Debugging the CPU Software using SILENT Mode 3.3.5. Resetting the CPU upon Fault Detection
3.3.1. Applying Timeout and Comparator Blind Window x
3.3.1.1. Timeout 3.3.1.2. Comparator Blind Window 3.3.1.3. Calculating the Blind Window and Timeout Period
3.3.2. Injecting Fault x
3.3.2.1. Root Fault Injection 3.3.2.2. Alarm Fault Injection
3.3.4. Debugging the CPU Software using SILENT Mode x
3.3.4.1. Entering SILENT Mode 3.3.4.2. SILENT Mode Limitation 3.3.4.3. Exiting SILENT Mode
3.3.5. Resetting the CPU upon Fault Detection x
3.3.5.1. Basic Reset Control
4. Programming Model x
4.1. Memory Map 4.2. Configuring fRSmartComp during Run-time 4.3. Unlocking and Locking Registers 4.4. Detailed Register Description
4.1. Memory Map x
4.1.1. Memory Map—Part 1 4.1.2. Memory Map—Part 2 4.1.3. Memory Map—Part 3
4.4. Detailed Register Description x
4.4.1. DCLSM Blind Window Control Register - DCLSM_BWCR 4.4.2. All Alarms’ Prior Alarms’ Fault Injection Register - ERRCTRL_ALL_ALARMS_PRIOR_AFI 4.4.3. INTREQ Configuration Register - ERRCTRL_INTREQ_CONF 4.4.4. Timeout Deadline and Status Register - ERRCTRL_TIMEOUT 4.4.5. Timeout Acknowledgment Register - ERRCTRL_TIMEOUT_ACK 4.4.6. Enable Key fRSmartComp Control Register - ERRCTRL_ENABLE_KEY 4.4.7. Root Fault Injection Control register - ERRCTRL_ROOT_INJ 4.4.8. Alarm Fault Injection Control register - ERRCTRL_ALARM_INJ 4.4.9. Event Mask Configuration register - ERRCTRL_MASKA and ERRCTRL_MASKB 4.4.10. Alarm Routing Configuration register - ERRCTRL_ROUTA and ERRCTRL_ROUTB 4.4.11. Error Controller PGO LOG Reset Control register - ERRCTRL_PGOLOGRST 4.4.12. PGO0 and PGO4 Configuration registers - ERRCTRL_PGO0 and ERRCTRL_PGO4 4.4.13. FN_MODEIN Control Register - ERRCTRL_FNMODEIN 4.4.14. FN_MODEOUT register - ERRCTRL_FNMODEOUT 4.4.15. All Alarms After Fault Injection - ERRCTRL_FNGIALARMS 4.4.16. Error Controller Context Register - ERRCTRL_FNGICTXT4 4.4.17. CMP Mismatch CONTEXT Registers - ERRCTRL_FNGICMPCTXT0 … ERRCTRL_FNGICMPCTXT3 4.4.18. STATISTICS registers: ERRCTRL_FNGISTAT0 and ERRCTRL_FNGISTAT4 4.4.19. State register - ERRCTRL_FNPERIPHGI4
5. Signals, Interfaces, and Build Parameters x
5.1. Configuration Interface 5.2. System Interface 5.3. fRNET Interface 5.4. IP Parameters
5.3. fRNET Interface x
5.3.1. CONFIG 5.3.2. INFO
6. Using Nios® V Processor Lock Step x
6.1. Instantiating Lockstep-Enabled Processor 6.2. Connecting Signals and Interfaces 6.3. Compiling Design 6.4. Implementing Startup Procedure 6.5. Applying Optional Injection for Validation 6.6. Detecting Faults 6.7. Handling Faults (Safety Use Case)
6.2. Connecting Signals and Interfaces x
6.2.1. Connecting Clock and Reset 6.2.2. Connecting Configuration Interface 6.2.3. Connecting System Interface
6.2.1. Connecting Clock and Reset x
6.2.1.1. Clock 6.2.1.2. Reset
6.2.3. Connecting System Interface x
6.2.3.1. Asynchronous Reset Interface 6.2.3.2. CPU Halt and Restart Acknowledgment Interface 6.2.3.3. Silent Mode Interface 6.2.3.4. Output Qualification (TERMS_LEFT and TERMS_RIGHT) 6.2.3.5. Interrupt Request (INTREQ) 6.2.3.6. ALARMS Interfaces 6.2.3.7. Connecting fRNET Interface
6.7. Handling Faults (Safety Use Case) x
6.7.1. UC_01: Standard Fail Safe or No Availability 6.7.2. UC_02: False Positive Avoidance 6.7.3. UC_03: Timeout on System Reset or After Fault Detection
1. About the Nios® V Processor Lockstep
2. Overview
3. Controlling the Nios® V Processor Lockstep
4. Programming Model
5. Signals, Interfaces, and Build Parameters
6. Using Nios® V Processor Lock Step
A. Document Revision History for the Nios® V Processor: Lockstep Implementation
B. Appendix

3.3.2.1. Root Fault Injection

The Root Fault injection is available for the following alarms:

  • Comparator mismatch (including selecting the Comparator Context bit to be activated). ALARM0 and ALARM1 are activated.
  • Comparator self-detection. ALARM2, ALARM3, and ALARM4 are activated.
  • Timeout. ALARM16 is activated.

You can activate the Root Fault Injection using the interfaces listed in the following table:

Table 20.  Activating Root Fault Injection
Interface Actions
Configuration Interface Writing the ERRCTRL_ROOT_INJ register.
fRNET Interface Writing the FRNET_PGO_ROOT_FAULT_INJ input.

In addition to the above activation steps, in the case of an ALARM0 or ALARM1 injection, using ERRCTRL_PGO0[6:0] register or FRNET_PERIPH_PGO_0[6:0] input is necessary to select which comparator slice to inject. Injecting a disabled comparator slice results in no injection being performed. Slice0 is selected automatically as default comparator slice after asynchronous reset.

After root fault injection, the Nios® V processor Lockstep feature does not register the injected slice ID into ERRCTRL_FNGICMPCTXT0 register. This register is updated only during a true mismatch event (unaffected during an injection).

Table 21.  Root Fault Injection
Injection Type Activation (through Configuration Interface) Fault Emulation Stimulated Alarm
Comparator Mismatch Ensure that all the following conditions are present:
  • ERRCTRL_ROOT_INJ[0]=1’b1
  • ERRCTRL_ROOT_INJ[1]=1’b1

Injection Target: RESETACK (selected automatically due to Slice0).
  • Main comparator mismatch
  • Second comparator mismatch
 If under DISABLED state, it stimulates ALARM0. Otherwise, it stimulates ALARM1.
Comparator Self-detection Ensure that all the following conditions are present:
  • ERRCTRL_ROOT_INJ[0]=1’b1
  • ERRCTRL_ROOT_INJ[1]=1’b0
  • ERRCTRL_ROOT_INJ[2]=1’b0

Injection Target: RESETACK (selected automatically due to Slice0).
  • Main comparator mismatch
  • Both comparators disagree

If under DISABLED state, it activates ALARM0. Otherwise, it activates ALARM1.

ALARM2 and ALARM3 is activated.

Comparator Self-detection Ensure that all the following conditions are present:
  • ERRCTRL_ROOT_INJ[0]=1’b0,
  • ERRCTRL_ROOT_INJ[1]=1’b1, and
  • ERRCTRL_ROOT_INJ[2]=1’b1

Injection Target: RESETACK (selected automatically due to Slice0).
  • Second comparator mismatch
  • Both comparators disagree
  • Self-diagnostic comparator mismatch

If under DISABLED state, it activates ALARM0. Otherwise, it activates ALARM1.

ALARM2 and ALARM4 is activated.
Timeout ERRCTRL_ROOT_INJ[16]=1’b1 Timeout alarm ALARM16 is activated.

The time taken to execute the Root Fault injection and to activate the required alarms is 70 CLK clock cycles at maximum (as the third self-diagnostic comparison is a time-multiplexed one).

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