Revert "soc/intel/cannonlake: Remove DMA support for PTT"

This reverts commit d5018a8f78.

Reason for revert: Breaks boot on Whiskey Lake-U boards

Both System76 and Purism have had memory initialization failures
when this patch is applied, with the following error message:
Failed to accommodate FSP reserved memory request!

An extra 4096 bytes needs to be reserved for the FSP on these
systems, and reinstating the PTT reservation does this as
expected. PTT is enabled for the System76 galp3-c in the
ME configuration, which is why the behaviour is different.

Signed-off-by: Jeremy Soller <jeremy@system76.com>
CC: Matt DeVillier <matt.devillier@gmail.com>
CC: Subrata Banik <subrata.banik@intel.com>
Change-Id: Ib82f02c4a2b1cd2dbf95d4ca4a9edd314e78edd2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35924
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Lance Zhao <lance.zhao@gmail.com>
Reviewed-by: Michael Niewöhner
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/cannonlake/include/soc/iomap.h

@@ -68,6 +68,10 @@
 
 #define HECI1_BASE_ADDRESS	0xfeda2000
 
+/* PTT registers */
+#define PTT_TXT_BASE_ADDRESS	0xfed30800
+#define PTT_PRESENT		0x00070000
+
 #define VTD_BASE_ADDRESS	0xFED90000
 #define VTD_BASE_SIZE		0x00004000
 /*

src/soc/intel/cannonlake/memmap.c

@@ -37,6 +37,22 @@ void smm_region(uintptr_t *start, size_t *size)
 	*size = sa_get_tseg_size();
 }
 
+static bool is_ptt_enable(void)
+{
+	if ((read32((void *)PTT_TXT_BASE_ADDRESS) & PTT_PRESENT) ==
+			PTT_PRESENT)
+		return true;
+
+	return false;
+}
+
+/* Calculate PTT size */
+static size_t get_ptt_size(void)
+{
+	/* Allocate 4KB for PTT if enabled */
+	return is_ptt_enable() ? 4*KiB : 0;
+}
+
 /* Calculate ME Stolen size */
 static size_t get_imr_size(void)
 {
@@ -130,6 +146,9 @@ static size_t calculate_reserved_mem_size(uintptr_t dram_base,
 	/* Get Tracehub size */
 	reserve_mem_base -= get_imr_size();
 
+	/* Get PTT size */
+	reserve_mem_base -= get_ptt_size();
+
 	/* Traditional Area Size */
 	reserve_mem_size = dram_base - reserve_mem_base;