ELOG: Support for non-memory mapped flash

If the event log is stored in flash that is not memory
mapped then it must use the SPI controller to read from
the flash device instead of relying on memory accesses.

In addition a new CBMEM ID is added to keep an resident
copy of the ELOG around if needed.  The use of CBMEM for
this is guarded by a new CONFIG_ELOG_CBMEM config option.
This CBMEM buffer is created and filled late in the process
when the SMBIOS table is being created because CBMEM is
not functional when ELOG is first initialized.

The downside to using CBMEM is that events added via the
SMI handler at runtime are not reflected in the CBMEM copy
because I don't want to let the SMM handler write to memory
outside the TSEG region.

In reality the only time we add runtime events is at kernel
shutdown so the impact is limited.

Test:
1) Test with CONFIG_ELOG_CBMEM enabled to ensure the event
log is operational and SMBIOS points to address in CBMEM.
The test should involve at least on reboot to ensure that the
kernel is able to write events as well.

> mosys -l smbios info log | grep ^address
address              | 0xacedd000

> mosys eventlog list
0 | 2012-10-10 14:02:46 | Log area cleared | 4096
1 | 2012-10-10 14:02:46 | System boot | 478
2 | 2012-10-10 14:02:46 | System Reset
3 | 2012-10-10 14:03:33 | Kernel Event | Clean Shutdown
4 | 2012-10-10 14:03:34 | System boot | 479
5 | 2012-10-10 14:03:34 | System Reset

2) Test with CONFIG_ELOG_CBMEM disabled to ensure the event
log is operational and SMBIOS points to memory mapped flash.
The test should involve at least on reboot to ensure that the
kernel is able to write events as well.

> mosys -l smbios info log | grep ^address
address              | 0xffbf0000

> mosys eventlog list
0 | 2012-10-10 14:33:17 | Log area cleared | 4096
1 | 2012-10-10 14:33:18 | System boot | 480
2 | 2012-10-10 14:33:18 | System Reset
3 | 2012-10-10 14:33:35 | Kernel Event | Clean Shutdown
4 | 2012-10-10 14:33:36 | System boot | 481
5 | 2012-10-10 14:33:36 | System Reset

Change-Id: I87755d5291ce209c1e647792227c433dc966615d
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1776
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/drivers/elog/elog_internal.h b/src/drivers/elog/elog_internal.h
index 6d9a0d4bb5..f6aa051007 100644
--- a/src/drivers/elog/elog_internal.h
+++ b/src/drivers/elog/elog_internal.h
@@ -78,8 +78,9 @@ struct elog_descriptor {
 	elog_header_state	header_state;
 	elog_event_buffer_state	event_buffer_state;
 	struct elog_header	*staging_header;
-	void                    *backing_store;
+	void			*backing_store;
 	u8			*data;
+	u32			flash_base;
 	u16                     total_size;
 	u16			data_size;
 	u16			next_event_offset;