ELOG: Add support for flash based event log

This is based around the SMBIOS event log specification but
expanded with OEM event types to support more specific and
relevant system events.

It requires flash storage and a minimum 4K block (or flash block
size) that should be allocated in the FMAP.

A copy of the event log is maintained in memory for convenience
and speed and the in-memory copy is written to flash at specific
points.

The log is automatically shunk when it reaches a configurable
full threshold in order to not get stuck with a full log that
needs OS help to clear.

ELOG implements the specification published here:
http://code.google.com/p/firmware-event-log/wiki/FirmwareEventLogDesign

And is similar to what we use in other firmware at Google.
This implementation does not support double-buffered flash
regions.  This is done because speed is valued over the log
reliability and it keeps the code simpler for the first version.

This is a large commit and by itself it just provides a new
driver that is made available to coreboot.  Without additional
patches it is not very useful, but the end result is an event
log that will contain entries like this:

171 | 2012-06-23 16:02:55 | System boot | 285
172 | 2012-06-23 16:02:55 | EC Event | Power Button
173 | 2012-06-23 16:02:55 | SUS Power Fail
174 | 2012-06-23 16:02:55 | System Reset
175 | 2012-06-23 16:02:55 | ACPI Wake | S5

Change-Id: I985524c67f525c8a268eccbd856c1a4c2a426889
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1311
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/drivers/elog/Makefile.inc b/src/drivers/elog/Makefile.inc
new file mode 100644
index 0000000000..a01841db96
--- /dev/null
+++ b/src/drivers/elog/Makefile.inc
@@ -0,0 +1 @@
+ramstage-$(CONFIG_ELOG) += elog.c