OMAP4 Power and Clock Management Instrumentation

Overview

Power Management Instrumentation (PMI) and Clock Management Instrumentation (CMI) modules provide state monitoring on a sample window basis
Event (PMI & CMI) and Activity (CMI only) monitoring (although not at the same time)
STM Event messages are accumulated for a sample period, if no events no messages
Activity monitoring provides status messages for every sample window
Sample windows, EMU pin triggers, and domain selection for monitoring are all programmable
Multiple events in a sample window

-If the events are of the same class, the PMI and CMI units will post the first event and then declare an error on that event if another identical event occurs in the sample window. This information will show up in the Trace Status column of the display.

-If multiple events of different classes occur in the same sample window, the later class event messages are delayed to subsequent sample windows (up to 16). In this case the message will be realigned to have the same timestamp as the first event.

PMI and CMI modules have independent clock domains

-The PMI module clock is derived from SYS_CLK, the CMI modules clocks are derived from CORE DPLL.

-The PMI/CMI clocks shall be the last to die to allow complete reporting of all power & clock use cases.

Tools Support

Support through CCS UBM and CTools PMI/CMI Library (for application integration)
UBM Support

- Both PMI and CMI STM Trace Jobs can be configured through CCS's Breakpoint Manager

- PMI and CM1 are enabled by default, CM2 must be added through an additional STM Trace Job

- Can setup multiple STM Trace Jobs, one per PM and CM modules, at the same time

- UBM Limitation

=> To enable a STM Trace Job a processor must be halted (ex: CortexA9_0)

=> To capture initial Events (PM and CMI) the XDS Trace Receiver must be in the recording state when the Trace Job is enabled

CTools Library

- Seprate PMI and CMI APIs, but the two libraries can be built together to take advantage of shared modules

- Complete Doxygen documentation per API

- Library is written to be portable between environments, so external helper functions used to provide memory allocation and mapping (Linux) support

- Build options

=> A common PMI/CMI build (single library) or as stand alone libraries

=> If _STMLogging (0.4 release) is defined, APIs are included that provide additional logging capabilities but require the STM Library

- Configure STM export from the device device

- Configure the Trace Receiver (through Trace Control)

- Must use a CCS UBM System Trace Job to enable PM, CM1 and CM2 (PM and CM1 are enabled by default)

Linux Kernel Module/Driver

- Loadable kernel module with initialization parameters

- Exported kernel API for control from other kernel modules

- Device driver support for control from user space

- Ownership and use of module on first come first served basis

Demo of Power and Clock status output via CCS: Media:PMCMconfig2.swf

Note: Adobe Flash required. Video is 1024x768, view it full screen

Tabular view

Logic analyzer view

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