When the 'idle' configuration parameter is set, this function will be added to the list of Idle loop functions. When called from the Idle loop, it will invoke the wait for interrupt (WFI) instruction, to idle the CPU until the next interrupt occurs.

Precondition and usage constraints:

1) Before this function is called the application must disable all interrupts that are not desired to wake the CPU from WFI while waiting for the core domain to go off.

2) For those interrupts that are desired to wake the CPU from WFI (for example, the mailbox interrupt), these interrupts cannot be generated until the Power_suspend API has reached the point of executing WFI. If the interrupts happen early, while this API is saving context, the resulting context may be stale, and the application may not resume correctly. Two global flags (one for each M3 core) are assert immediately before invoking WFI; the wakeup interrupts should not be asserted until these flags are asserted (non-zero): ti_sysbios_family_arm_ducati_omap4430_readyIdleCore0 ti_sysbios_family_arm_ducati_omap4430_readyIdleCore1

All modules have this configuration parameter. Its name contains the '$' character to ensure it does not conflict with configuration parameters declared by the module. This allows new configuration parameters to be added in the future without any chance of breaking existing modules.