Source: http://arago-project.org/git/projects/?p=am33x-cm3.git;a=summary

This is the README for the Cortex-M3 (CM3) firmware for power management
on Texas Instruments' AM33XX series of SoCs.

AM33XX integrates a Cortex-M3 core to manage the entry/exit of various
standy-by and deep-sleep mode. More info on this is present in the
AM335X Techinal Reference Manual (TRM) available @ www.ti.com

DOCUMENTATION:

 - The CM3 firmware design document can be found under the
   Documentation/ folder. SA_PM_Firmware.pdf is the best place to start.

 - Most of the diagrams used in the pdf were created using
   Dia, a GTK+ based digram creation program. The original
   *.dia files are also available under Documentation/

 - For more technical detailis refer to the TRM on the TI website.

COMPILING the firmare:

 - Refer to the AM335x PSP User-guide for the toolchain to be used for
   the Linux kernel compilation and how to get it. The same toolchain
   needs to be used for compiling the CM3 firmware.

 - With the toolchain installed and PATH setup to point to it, do a
   "make" to create the CM3 firmware. The binary and ELF files are
   by default put in the bin/ folder.

 - The binary file needs to be loaded to CM3 from the Cortex-A8 core
   before all the PM features are available.

 - For using the CM3 firmware with the Linux kernel refer to the
   the PSP User Guide

PREBUILT binary:

 - Prebuilt binaries are available under the bin/ folder