Documentation/metag/coremem.txt

Meta Core Memory
================

The files coremem.h and coremem.c implement the main interface which allows
suspend code to copy a suspend routine into core memory so that DDR can be put
into self refresh and the DDRC powered down.

metag_coremem_alloc() reserves a section of core mem according to some flags.

metag_coremem_free() indicates that the memory is finished with.

metag_coremem_push() memcpy's data to the next space in the core memory and
moves the free pointer onwards. This is intended for copying asm function code
into instruction memory.

metag_coremem_alloc uses a simple array of coremem regions to find an
appropriate region to allocate. This array is defined for TZ1090 only at the
moment (soc/tz1090/coremem.c).


Locked in Core Cache Mode
-------------------------

Locked in core instruction cache memory can be asked for. After the code is
prefetched or executed to lock the code into the icache it is possible to
power down the DDR controller. Since this cache is thread specific it does not
interfere with the running of other threads.

The actual setup is done by metag_coremem_push (which can only be called once
after a metag_coremem_alloc). See soc/tz1090/suspend.S for an example of
prefetching code into the icache to get it locked in. It is not currently
possible to use ICACHE and DCACHE coremem regions at the same time.