Watchdog Timer Module

Introduction

The Watchdog Timer Module provides configuration and use of the watchdog timer mode for the DSP local timers. The watchdog mode is a 64-bit timer mode for the local timers. When configured in the watchdog mode the timer will count up to a configured 64-bit period value. The count is incremented for each DSP clock tick. Periodically the DSP must "service" the watchdog timer by writing a sequence of values to the timer control registers. When the watchdog timer is serviced correctly the count will reset to zero and then resume counting up to the timer period value. If for any reason the count value reaches the timer period a watchdog timer event will be triggered. The actions taken by the triggered event are based on the watchdog timer configurations in the timer control registers and the device reset block.

In general, a device's timer n maps to DSP core n's local timer. The DSP local timers are the only timers in the system capable of operating in the watchdog timer mode. This means that each DSP core has only one timer capable of acting as its watchdog timer. Please keep this in mind when using this module. Any applications integrated with this module must not make use of the DSP local timer as it will taken by this module to be used as the watchdog timer. Module configuration parameters are specifically provided to handle reconfiguring the timer used by BIOS at startup for the Clock module.

Watchdog Timer Mapping: DSP Timer 0 -> Core 0 Local/Watchdog Timer
DSP Timer 1 -> Core 1 Local/Watchdog Timer
DSP Timer 2 -> Core 2 Local/Watchdog Timer
DSP Timer 3 -> Core 3 Local/Watchdog Timer
DSP Timer n -> Core n Local/Watchdog Timer

DSPs can be configured to take different actions if its configured watchdog timer were to expire. These actions can be configured via the configuration structure passed to the Watchdog Timer module's _Init function. The watchdog timer can be configured to generate local hard and soft resets when the watchdog expires. It can also be configured to generate an NMI or an NMI followed by a local reset after a configurable number of clock cycles. A major functionality of the watchdog timer expiration actions is the generation of a System event that can be registered as a system exception in the INTC exception combiner. This allows the BIOS Exception module to handle an exception generated by the expiration of the watchdog timer. Since the BIOS Exception module is capable of handling the watchdog timer expiration exception other fault management capabilities, like core dumps, can be executed when the watchdog timer expires.

For Watchdog Timer Module API information please see the WatchdogTimer.xdc file.

For device information on the watchdog timer operation please see:
SPRUGV5A - Keystone Architecture Timer64P User Guide


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