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, 47 insertions, 0 deletions

diff --git a/src/soc/intel/skylake/memmap.c b/src/soc/intel/skylake/memmap.c
index 81ec89d95d..494b259455 100644
--- a/src/soc/intel/skylake/memmap.c
+++ b/src/soc/intel/skylake/memmap.c
@@ -61,6 +61,53 @@ void smm_region(void **start, size_t *size)
 	*size = smm_region_size();
 }
 
+/*
+ *        Subregions within SMM
+ *     +-------------------------+ BGSM
+ *     |          IED            | IED_REGION_SIZE
+ *     +-------------------------+
+ *     |  External Stage Cache   | SMM_RESERVED_SIZE
+ *     +-------------------------+
+ *     |      code and data      |
+ *     |         (TSEG)          |
+ *     +-------------------------+ TSEG
+ */
+int smm_subregion(int sub, void **start, size_t *size)
+{
+	uintptr_t sub_base;
+	size_t sub_size;
+	const size_t ied_size = CONFIG_IED_REGION_SIZE;
+	const size_t cache_size = CONFIG_SMM_RESERVED_SIZE;
+
+	sub_base = smm_region_start();
+	sub_size = smm_region_size();
+
+	switch (sub) {
+	case SMM_SUBREGION_HANDLER:
+		/* Handler starts at the base of TSEG. */
+		sub_size -= ied_size;
+		sub_size -= cache_size;
+		break;
+	case SMM_SUBREGION_CACHE:
+		/* External cache is in the middle of TSEG. */
+		sub_base += sub_size - (ied_size + cache_size);
+		sub_size = cache_size;
+		break;
+	case SMM_SUBREGION_CHIPSET:
+		/* IED is at the top. */
+		sub_base += sub_size - ied_size;
+		sub_size = ied_size;
+		break;
+	default:
+		return -1;
+	}
+
+	*start = (void *)sub_base;
+	*size = sub_size;
+
+	return 0;
+}
+
 void *cbmem_top(void)
 {
 	/*