intel/common: fix stage_cache_external_region()

The stage_cache_external_region() calculation is actually
dependennt on the properties of the chipset. The reason
is that certain regions within the SMRAM are used for
chipset-specific features. Therefore, provide an API
for abstracting the querying of subregions within
the SMRAM.

The 3 subregions introduced are:

SMM_SUBREGION_HANDLER - SMM handler area
SMM_SUBREGION_CACHE - SMM cache region
SMM_SUBREGION_CHIPSET - Chipset specific area.

The subregions can be queried using the newly
added smm_subregion() function.

Now stage_cache_external_region() uses smm_subregion()
to query the external stage cache in SMRAM, and this
patch also eliminates 2 separate implementations of
stage_cache_external_region() between romstage and
ramstage.

BUG=chrome-os-partner:43636
BRANCH=None
TEST=Built, booted, suspended, resumed on glados.

Original-Change-Id: Id669326ba9647117193aa604038b38b364ff0f82
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/290833
Original-Reviewed-by: Leroy P Leahy <leroy.p.leahy@intel.com>
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

Change-Id: Idb1a75d93c9b87053a7dedb82e85afc7df6334e0
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/11197
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/soc/intel/common/memmap.h b/src/soc/intel/common/memmap.h
index d94f0add7f..3d51539f55 100644
--- a/src/soc/intel/common/memmap.h
+++ b/src/soc/intel/common/memmap.h
@@ -28,6 +28,24 @@
  * this value should be set to 8 MiB.
  */
 size_t mmap_region_granluarity(void);
+
+/* Fills in the arguments for the entire SMM region covered by chipset
+ * protections. e.g. TSEG. */
 void smm_region(void **start, size_t *size);
 
+enum {
+	/* SMM handler area. */
+	SMM_SUBREGION_HANDLER,
+	/* SMM cache region. */
+	SMM_SUBREGION_CACHE,
+	/* Chipset specific area. */
+	SMM_SUBREGION_CHIPSET,
+	/* Total sub regions supported. */
+	SMM_SUBREGION_NUM,
+};
+
+/* Fills in the start and size for the requested SMM subregion. Returns
+ * 0 on susccess, < 0 on failure. */
+int smm_subregion(int sub, void **start, size_t *size);
+
 #endif /* _COMMON_MEMMAP_H_ */