amd/amdmct/mct_ddr3: Use training values from previous boot if possible

DRAM training accounts for most of the romstage startup time, yet
if the hardware configuration has not changed from the previous boot
the previously discovered training values are still valid.  Use them
if the DIMM configuration has not changed since the last boot.

The SPD values of all installed DIMMs are hashed and stored in the S3
resume data area of the main system Flash device.  If a DIMM is changed
the hash will almost certainly change as well, forcing retraining on next
boot.

Change-Id: I37ed277b16476d38e4af76c6ae827a575c6b017d
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: http://review.coreboot.org/11976
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

5 files changed, 288 insertions, 52 deletions

diff --git a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
index 0718477872..ad0e6e807b 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
+++ b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
@@ -35,7 +35,8 @@
 static u8 ReconfigureDIMMspare_D(struct MCTStatStruc *pMCTstat,
 					struct DCTStatStruc *pDCTstatA);
 static void DQSTiming_D(struct MCTStatStruc *pMCTstat,
-				struct DCTStatStruc *pDCTstatA);
+				struct DCTStatStruc *pDCTstatA,
+				uint8_t allow_config_restore);
 static void LoadDQSSigTmgRegs_D(struct MCTStatStruc *pMCTstat,
 					struct DCTStatStruc *pDCTstatA);
 static void HTMemMapInit_D(struct MCTStatStruc *pMCTstat,
@@ -1169,6 +1170,30 @@ static void read_spd_bytes(struct MCTStatStruc *pMCTstat,
 	}
 }
 
+#if IS_ENABLED(CONFIG_HAVE_ACPI_RESUME)
+static void calculate_and_store_spd_hashes(struct MCTStatStruc *pMCTstat,
+				struct DCTStatStruc *pDCTstat)
+{
+	uint8_t dimm;
+
+	for (dimm = 0; dimm < MAX_DIMMS_SUPPORTED; dimm++) {
+		calculate_spd_hash(pDCTstat->spd_data.spd_bytes[dimm], &pDCTstat->spd_data.spd_hash[dimm]);
+	}
+}
+
+static void compare_nvram_spd_hashes(struct MCTStatStruc *pMCTstat,
+				struct DCTStatStruc *pDCTstat)
+{
+	uint8_t dimm;
+
+	pDCTstat->spd_data.nvram_spd_match = 1;
+	for (dimm = 0; dimm < MAX_DIMMS_SUPPORTED; dimm++) {
+		if (pDCTstat->spd_data.spd_hash[dimm] != pDCTstat->spd_data.nvram_spd_hash[dimm])
+			pDCTstat->spd_data.nvram_spd_match = 0;
+	}
+}
+#endif
+
 static void mctAutoInitMCT_D(struct MCTStatStruc *pMCTstat,
 			struct DCTStatStruc *pDCTstatA)
 {
@@ -1217,6 +1242,8 @@ static void mctAutoInitMCT_D(struct MCTStatStruc *pMCTstat,
 	 */
 	u8 Node, NodesWmem;
 	u32 node_sys_base;
+	uint8_t nvram;
+	uint8_t allow_config_restore;
 
 	uint8_t s3resume = acpi_is_wakeup_s3();
 
@@ -1233,7 +1260,8 @@ restartinit:
 
 #if IS_ENABLED(CONFIG_HAVE_ACPI_RESUME)
 		printk(BIOS_DEBUG, "mctAutoInitMCT_D: Restoring DCT configuration from NVRAM\n");
-		restore_mct_information_from_nvram();
+		if (restore_mct_information_from_nvram(0) != 0)
+			printk(BIOS_CRIT, "%s: ERROR: Unable to restore DCT configuration from NVRAM\n", __func__);
 #endif
 
 		printk(BIOS_DEBUG, "mctAutoInitMCT_D: mct_ForceNBPState0_Dis_Fam15\n");
@@ -1283,11 +1311,26 @@ restartinit:
 			node_sys_base += (pDCTstat->NodeSysLimit + 2) & ~0x0F;
 		}
 
+		/* If the boot fails make sure training is attempted after reset */
+		nvram = 0;
+		set_option("allow_spd_nvram_cache_restore", &nvram);
+
 #if IS_ENABLED(DIMM_VOLTAGE_SET_SUPPORT)
 		printk(BIOS_DEBUG, "%s: DIMMSetVoltage\n", __func__);
 		DIMMSetVoltages(pMCTstat, pDCTstatA);	/* Set the DIMM voltages (mainboard specific) */
 #endif
 
+		/* If DIMM configuration has not changed since last boot restore training values */
+		allow_config_restore = 1;
+		for (Node = 0; Node < MAX_NODES_SUPPORTED; Node++) {
+			struct DCTStatStruc *pDCTstat;
+			pDCTstat = pDCTstatA + Node;
+
+			if (pDCTstat->NodePresent)
+				if (!pDCTstat->spd_data.nvram_spd_match)
+					allow_config_restore = 0;
+		}
+
 		for (Node = 0; Node < MAX_NODES_SUPPORTED; Node++) {
 			struct DCTStatStruc *pDCTstat;
 			pDCTstat = pDCTstatA + Node;
@@ -1321,14 +1364,33 @@ restartinit:
 		CPUMemTyping_D(pMCTstat, pDCTstatA);	/* Map dram into WB/UC CPU cacheability */
 		mctHookAfterCPU();			/* Setup external northbridge(s) */
 
+		/* FIXME
+		 * Previous training values should only be used if the current desired
+		 * speed is the same as the speed used in the previous boot.
+		 * How to get the desired speed at this point in the code?
+		 */
+#if 0
+		for (Node = 0; Node < MAX_NODES_SUPPORTED; Node++) {
+			struct DCTStatStruc *pDCTstat;
+			pDCTstat = pDCTstatA + Node;
+
+			if (pDCTstat->NodePresent) {
+				if (pDCTstat->spd_data.nvram_memclk[0] != pDCTstat->DIMMAutoSpeed)
+					allow_config_restore = 0;
+			}
+		}
+#endif
+
 		printk(BIOS_DEBUG, "mctAutoInitMCT_D: DQSTiming_D\n");
-		DQSTiming_D(pMCTstat, pDCTstatA);	/* Get Receiver Enable and DQS signal timing*/
+		DQSTiming_D(pMCTstat, pDCTstatA, allow_config_restore);	/* Get Receiver Enable and DQS signal timing*/
 
 		printk(BIOS_DEBUG, "mctAutoInitMCT_D: UMAMemTyping_D\n");
 		UMAMemTyping_D(pMCTstat, pDCTstatA);	/* Fix up for UMA sizing */
 
-		printk(BIOS_DEBUG, "mctAutoInitMCT_D: :OtherTiming\n");
-		mct_OtherTiming(pMCTstat, pDCTstatA);
+		if (!allow_config_restore) {
+			printk(BIOS_DEBUG, "mctAutoInitMCT_D: :OtherTiming\n");
+			mct_OtherTiming(pMCTstat, pDCTstatA);
+		}
 
 		if (ReconfigureDIMMspare_D(pMCTstat, pDCTstatA)) { /* RESET# if 1st pass of DIMM spare enabled*/
 			goto restartinit;
@@ -1810,7 +1872,7 @@ static void exit_training_mode_fam15(struct MCTStatStruc *pMCTstat,
 }
 
 static void DQSTiming_D(struct MCTStatStruc *pMCTstat,
-				struct DCTStatStruc *pDCTstatA)
+				struct DCTStatStruc *pDCTstatA, uint8_t allow_config_restore)
 {
 	u8 nv_DQSTrainCTL;
 
@@ -1818,9 +1880,8 @@ static void DQSTiming_D(struct MCTStatStruc *pMCTstat,
 		return;
 	}
 
-	nv_DQSTrainCTL = mctGet_NVbits(NV_DQSTrainCTL);
-	/* FIXME: BOZO- DQS training every time*/
-	nv_DQSTrainCTL = 1;
+	// nv_DQSTrainCTL = mctGet_NVbits(NV_DQSTrainCTL);
+	nv_DQSTrainCTL = !allow_config_restore;
 
 	mct_BeforeDQSTrain_D(pMCTstat, pDCTstatA);
 	phyAssistedMemFnceTraining(pMCTstat, pDCTstatA);
@@ -1839,15 +1900,16 @@ static void DQSTiming_D(struct MCTStatStruc *pMCTstat,
 		}
 	}
 
+	mctHookBeforeAnyTraining(pMCTstat, pDCTstatA);
+	if (!is_fam15h()) {
+		/* TODO: should be in mctHookBeforeAnyTraining */
+		_WRMSR(0x26C, 0x04040404, 0x04040404);
+		_WRMSR(0x26D, 0x04040404, 0x04040404);
+		_WRMSR(0x26E, 0x04040404, 0x04040404);
+		_WRMSR(0x26F, 0x04040404, 0x04040404);
+	}
+
 	if (nv_DQSTrainCTL) {
-		mctHookBeforeAnyTraining(pMCTstat, pDCTstatA);
-		if (!is_fam15h()) {
-			/* TODO: should be in mctHookBeforeAnyTraining */
-			_WRMSR(0x26C, 0x04040404, 0x04040404);
-			_WRMSR(0x26D, 0x04040404, 0x04040404);
-			_WRMSR(0x26E, 0x04040404, 0x04040404);
-			_WRMSR(0x26F, 0x04040404, 0x04040404);
-		}
 		mct_WriteLevelization_HW(pMCTstat, pDCTstatA, FirstPass);
 
 		if (is_fam15h()) {
@@ -1877,18 +1939,26 @@ static void DQSTiming_D(struct MCTStatStruc *pMCTstat,
 			exit_training_mode_fam15(pMCTstat, pDCTstatA);
 		else
 			mctSetEccDQSRcvrEn_D(pMCTstat, pDCTstatA);
+	} else {
+		mct_WriteLevelization_HW(pMCTstat, pDCTstatA, FirstPass);
 
-		/* FIXME - currently uses calculated value	TrainMaxReadLatency_D(pMCTstat, pDCTstatA); */
-		mctHookAfterAnyTraining();
-		mctSaveDQSSigTmg_D();
+		mct_WriteLevelization_HW(pMCTstat, pDCTstatA, SecondPass);
 
-		MCTMemClr_D(pMCTstat, pDCTstatA);
-	} else {
-		mctGetDQSSigTmg_D();	/* get values into data structure */
-		LoadDQSSigTmgRegs_D(pMCTstat, pDCTstatA);	/* load values into registers.*/
-		/* mctDoWarmResetMemClr_D(); */
-		MCTMemClr_D(pMCTstat, pDCTstatA);
+#if IS_ENABLED(CONFIG_HAVE_ACPI_RESUME)
+		printk(BIOS_DEBUG, "mctAutoInitMCT_D: Restoring DIMM training configuration from NVRAM\n");
+		if (restore_mct_information_from_nvram(1) != 0)
+			printk(BIOS_CRIT, "%s: ERROR: Unable to restore DCT configuration from NVRAM\n", __func__);
+#endif
+
+		if (is_fam15h())
+			exit_training_mode_fam15(pMCTstat, pDCTstatA);
 	}
+
+	/* FIXME - currently uses calculated value	TrainMaxReadLatency_D(pMCTstat, pDCTstatA); */
+	mctHookAfterAnyTraining();
+
+	/* mctDoWarmResetMemClr_D(); */
+	MCTMemClr_D(pMCTstat, pDCTstatA);
 }
 
 static void LoadDQSSigTmgRegs_D(struct MCTStatStruc *pMCTstat,
@@ -3898,6 +3968,8 @@ static void mct_preInitDCT(struct MCTStatStruc *pMCTstat,
 				struct DCTStatStruc *pDCTstat)
 {
 	u8 err_code;
+	uint8_t nvram;
+	uint8_t allow_config_restore;
 
 	/* Preconfigure DCT0 */
 	DCTPreInit_D(pMCTstat, pDCTstat, 0);
@@ -3912,6 +3984,27 @@ static void mct_preInitDCT(struct MCTStatStruc *pMCTstat,
 				pDCTstat->ErrCode = err_code;	/* Using DCT0 Error code to update pDCTstat.ErrCode */
 		}
 	}
+
+#if IS_ENABLED(CONFIG_HAVE_ACPI_RESUME)
+	calculate_and_store_spd_hashes(pMCTstat, pDCTstat);
+
+	if (load_spd_hashes_from_nvram(pDCTstat) < 0) {
+		pDCTstat->spd_data.nvram_spd_match = 0;
+	}
+	else {
+		compare_nvram_spd_hashes(pMCTstat, pDCTstat);
+	}
+#else
+	pDCTstat->spd_data.nvram_spd_match = 0;
+#endif
+
+	/* Check to see if restoration of SPD data from NVRAM is allowed */
+	allow_config_restore = 0;
+	if (get_option(&nvram, "allow_spd_nvram_cache_restore") == CB_SUCCESS)
+		allow_config_restore = !!nvram;
+
+	if (!allow_config_restore)
+		pDCTstat->spd_data.nvram_spd_match = 0;
 }
 
 static void mct_initDCT(struct MCTStatStruc *pMCTstat,
diff --git a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.h b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.h
index e6b427ed7b..1ac7bbfe62 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.h
+++ b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.h
@@ -321,6 +321,10 @@ struct MCTStatStruc {
 struct amd_spd_node_data {
 	uint8_t spd_bytes[MAX_DIMMS_SUPPORTED][256];	/* [DIMM][byte] */
 	uint8_t spd_address[MAX_DIMMS_SUPPORTED];	/* [DIMM] */
+	uint64_t spd_hash[MAX_DIMMS_SUPPORTED];		/* [DIMM] */
+	uint64_t nvram_spd_hash[MAX_DIMMS_SUPPORTED];	/* [DIMM] */
+	uint8_t nvram_spd_match;
+	uint8_t nvram_memclk[2];			/* [channel] */
 } __attribute__((packed));
 
 struct DCTStatStruc {		/* A per Node structure*/
@@ -780,6 +784,8 @@ struct amd_s3_persistent_mct_channel_data {
 
 struct amd_s3_persistent_node_data {
 	uint32_t node_present;
+	uint64_t spd_hash[MAX_DIMMS_SUPPORTED];
+	uint8_t memclk[2];
 	struct amd_s3_persistent_mct_channel_data channel[2];
 } __attribute__((packed));
 
diff --git a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
index 3c2043be54..c4410443e0 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
+++ b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
@@ -22,8 +22,10 @@
 #include <device/pci_ops.h>
 #include <console/console.h>
 #include <cbfs.h>
+#include <cbmem.h>
 #include <spi-generic.h>
 #include <spi_flash.h>
+#include <pc80/mc146818rtc.h>
 
 #include "s3utils.h"
 
@@ -120,6 +122,68 @@ static uint32_t read_amd_dct_index_register_dct(device_t dev, uint8_t node, uint
 	return read_amd_dct_index_register(dev, index_ctl_reg, index);
 }
 
+/* Non-cryptographic 64-bit hash function taken from Stack Overflow:
+ * http://stackoverflow.com/a/13326345
+ * Any 64-bit hash with sufficiently low collision potential
+ * could be used instead.
+ */
+void calculate_spd_hash(uint8_t *spd_data, uint64_t *spd_hash)
+{
+	const unsigned long long prime = 2654435789ULL;
+	uint16_t byte;
+	*spd_hash = 104395301;
+
+	for (byte = 0; byte < 256; byte++)
+		*spd_hash += (spd_data[byte] * prime) ^ (*spd_hash >> 23);
+
+	*spd_hash = *spd_hash ^ (*spd_hash << 37);
+}
+
+static struct amd_s3_persistent_data * map_s3nv_in_nvram(void)
+{
+	ssize_t s3nv_offset;
+	ssize_t s3nv_file_offset;
+	void * s3nv_cbfs_file_ptr;
+	struct amd_s3_persistent_data *persistent_data;
+
+	/* Obtain CBFS file offset */
+	s3nv_offset = get_s3nv_file_offset();
+	if (s3nv_offset == -1)
+		return NULL;
+
+	/* Align flash pointer to nearest boundary */
+	s3nv_file_offset = s3nv_offset;
+	s3nv_offset &= ~(CONFIG_S3_DATA_SIZE-1);
+	s3nv_offset += CONFIG_S3_DATA_SIZE;
+	s3nv_file_offset = s3nv_offset - s3nv_file_offset;
+
+	/* Map data structure in CBFS and restore settings */
+	s3nv_cbfs_file_ptr = cbfs_boot_map_with_leak(S3NV_FILE_NAME, CBFS_TYPE_RAW, NULL);
+	if (!s3nv_cbfs_file_ptr) {
+		printk(BIOS_DEBUG, "S3 state file could not be mapped: %s\n", S3NV_FILE_NAME);
+		return NULL;
+	}
+	persistent_data = (s3nv_cbfs_file_ptr + s3nv_file_offset);
+
+	return persistent_data;
+}
+
+#ifdef __PRE_RAM__
+int8_t load_spd_hashes_from_nvram(struct DCTStatStruc *pDCTstat)
+{
+	struct amd_s3_persistent_data *persistent_data;
+
+	persistent_data = map_s3nv_in_nvram();
+	if (!persistent_data)
+		return -1;
+
+	memcpy(pDCTstat->spd_data.nvram_spd_hash, persistent_data->node[pDCTstat->Node_ID].spd_hash, sizeof(pDCTstat->spd_data.nvram_spd_hash));
+	memcpy(pDCTstat->spd_data.nvram_memclk, persistent_data->node[pDCTstat->Node_ID].memclk, sizeof(pDCTstat->spd_data.nvram_memclk));
+
+	return 0;
+}
+#endif
+
 #ifdef __RAMSTAGE__
 static uint64_t rdmsr_uint64_t(unsigned long index) {
 	msr_t msr = rdmsr(index);
@@ -145,6 +209,31 @@ static uint32_t read_config32_dct_nbpstate(device_t dev, uint8_t node, uint8_t d
 	return pci_read_config32(dev, reg);
 }
 
+static void copy_cbmem_spd_data_to_save_variable(struct amd_s3_persistent_data* persistent_data)
+{
+	uint8_t node;
+	uint8_t dimm;
+	uint8_t channel;
+	struct amdmct_memory_info *mem_info;
+	mem_info = cbmem_find(CBMEM_ID_AMDMCT_MEMINFO);
+	if (mem_info == NULL) {
+		/* can't find amdmct information in cbmem */
+		for (node = 0; node < MAX_NODES_SUPPORTED; node++)
+			for (dimm = 0; dimm < MAX_DIMMS_SUPPORTED; dimm++)
+				persistent_data->node[node].spd_hash[dimm] = 0xffffffffffffffffULL;
+
+		return;
+	}
+
+	for (node = 0; node < MAX_NODES_SUPPORTED; node++)
+		for (dimm = 0; dimm < MAX_DIMMS_SUPPORTED; dimm++)
+			calculate_spd_hash(mem_info->dct_stat[node].spd_data.spd_bytes[dimm], &persistent_data->node[node].spd_hash[dimm]);
+
+	for (node = 0; node < MAX_NODES_SUPPORTED; node++)
+		for (channel = 0; channel < 2; channel++)
+			persistent_data->node[node].memclk[channel] = mem_info->dct_stat[node].Speed;
+}
+
 void copy_mct_data_to_save_variable(struct amd_s3_persistent_data* persistent_data)
 {
 	uint8_t i;
@@ -437,7 +526,7 @@ static void wrmsr_uint64_t(unsigned long index, uint64_t value) {
 	wrmsr(index, msr);
 }
 
-void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persistent_data)
+void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persistent_data, uint8_t training_only)
 {
 	uint8_t i;
 	uint8_t j;
@@ -447,6 +536,51 @@ void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persiste
 	uint8_t dct_enabled;
 	uint32_t dword;
 
+	if (training_only) {
+		/* Only restore the Receiver Enable and DQS training registers */
+		for (node = 0; node < MAX_NODES_SUPPORTED; node++) {
+			for (channel = 0; channel < 2; channel++) {
+				struct amd_s3_persistent_mct_channel_data* data = &persistent_data->node[node].channel[channel];
+				if (!persistent_data->node[node].node_present)
+					continue;
+
+				/* Restore training parameters */
+				for (i=0; i<4; i++)
+					for (j=0; j<3; j++)
+						write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, (0x01 + i) + (0x100 * j), data->f2x9cx3_0_0_3_1[i][j]);
+				for (i=0; i<4; i++)
+					for (j=0; j<3; j++)
+						write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, (0x05 + i) + (0x100 * j), data->f2x9cx3_0_0_7_5[i][j]);
+
+				for (i=0; i<12; i++)
+					write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, 0x10 + i, data->f2x9cx10[i]);
+				for (i=0; i<12; i++)
+					write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, 0x20 + i, data->f2x9cx20[i]);
+
+				if (IS_ENABLED(CONFIG_DIMM_DDR3)) {
+					for (i=0; i<12; i++)
+						write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, 0x30 + i, data->f2x9cx30[i]);
+					for (i=0; i<12; i++)
+						write_amd_dct_index_register_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x98, 0x40 + i, data->f2x9cx40[i]);
+				}
+
+				/* Restore MaxRdLatency */
+				if (is_fam15h()) {
+					for (i=0; i<4; i++)
+						write_config32_dct_nbpstate(PCI_DEV(0, 0x18 + node, 2), node, channel, i, 0x210, data->f2x210[i]);
+				}
+				else {
+					write_config32_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x78, data->f2x78);
+				}
+
+				/* Other timing control registers */
+				write_config32_dct(PCI_DEV(0, 0x18 + node, 2), node, channel, 0x8c, data->f2x8c);
+			}
+		}
+
+		return;
+	}
+
 	/* Load data from data structure into DCTs */
 	/* Stage 1 */
 	for (node = 0; node < MAX_NODES_SUPPORTED; node++) {
@@ -497,7 +631,8 @@ void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persiste
 			wrmsr_uint64_t(0x00000250, data->msr00000250);
 			wrmsr_uint64_t(0x00000258, data->msr00000258);
 			/* FIXME
-			 * Restoring these MSRs causes a hang on resume
+			 * Restoring these MSRs causes a hang on resume due to
+			 * destroying CAR while still executing from CAR!
 			 * For now, skip restoration...
 			 */
 			// for (i=0; i<8; i++)
@@ -886,6 +1021,8 @@ void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persiste
 #ifdef __RAMSTAGE__
 int8_t save_mct_information_to_nvram(void)
 {
+	uint8_t nvram;
+
 	if (acpi_is_wakeup_s3())
 		return 0;
 
@@ -905,6 +1042,9 @@ int8_t save_mct_information_to_nvram(void)
 	/* Obtain MCT configuration data */
 	copy_mct_data_to_save_variable(persistent_data);
 
+	/* Save RAM SPD data at the same time */
+	copy_cbmem_spd_data_to_save_variable(persistent_data);
+
 	/* Obtain CBFS file offset */
 	s3nv_offset = get_s3nv_file_offset();
 	if (s3nv_offset == -1)
@@ -945,36 +1085,23 @@ int8_t save_mct_information_to_nvram(void)
 	/* Restore SPI MMIO address */
 	pci_write_config32(lpc_dev, 0xa0, spi_mmio_prev);
 
+	/* Allow training bypass if DIMM configuration is unchanged on next boot */
+	nvram = 1;
+	set_option("allow_spd_nvram_cache_restore", &nvram);
+
 	return 0;
 }
 #endif
 
-int8_t restore_mct_information_from_nvram(void)
+int8_t restore_mct_information_from_nvram(uint8_t training_only)
 {
-	ssize_t s3nv_offset;
-	ssize_t s3nv_file_offset;
-	void * s3nv_cbfs_file_ptr;
 	struct amd_s3_persistent_data *persistent_data;
 
-	/* Obtain CBFS file offset */
-	s3nv_offset = get_s3nv_file_offset();
-	if (s3nv_offset == -1)
+	persistent_data = map_s3nv_in_nvram();
+	if (!persistent_data)
 		return -1;
 
-	/* Align flash pointer to nearest boundary */
-	s3nv_file_offset = s3nv_offset;
-	s3nv_offset &= ~(CONFIG_S3_DATA_SIZE-1);
-	s3nv_offset += CONFIG_S3_DATA_SIZE;
-	s3nv_file_offset = s3nv_offset - s3nv_file_offset;
-
-	/* Map data structure in CBFS and restore settings */
-	s3nv_cbfs_file_ptr = cbfs_boot_map_with_leak(S3NV_FILE_NAME, CBFS_TYPE_RAW, NULL);
-	if (!s3nv_cbfs_file_ptr) {
-		printk(BIOS_DEBUG, "S3 state file could not be mapped: %s\n", S3NV_FILE_NAME);
-		return -1;
-	}
-	persistent_data = (s3nv_cbfs_file_ptr + s3nv_file_offset);
-	restore_mct_data_from_save_variable(persistent_data);
+	restore_mct_data_from_save_variable(persistent_data, training_only);
 
 	return 0;
-}
\ No newline at end of file
+}
diff --git a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.h b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.h
index 5370496615..56e627e413 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.h
+++ b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.h
@@ -16,9 +16,15 @@
 #include "../wrappers/mcti.h"
 #include "mct_d.h"
 
+void calculate_spd_hash(uint8_t *spd_data, uint64_t *spd_hash);
+
+#ifdef __PRE_RAM__
+int8_t load_spd_hashes_from_nvram(struct DCTStatStruc *pDCTstat);
+#endif
+
 #ifdef __RAMSTAGE__
 int8_t save_mct_information_to_nvram(void);
 #endif
-int8_t restore_mct_information_from_nvram(void);
+int8_t restore_mct_information_from_nvram(uint8_t training_only);
 void copy_mct_data_to_save_variable(struct amd_s3_persistent_data* persistent_data);
-void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persistent_data);
\ No newline at end of file
+void restore_mct_data_from_save_variable(struct amd_s3_persistent_data* persistent_data, uint8_t training_only);
diff --git a/src/northbridge/amd/amdmct/wrappers/mcti_d.c b/src/northbridge/amd/amdmct/wrappers/mcti_d.c
index 48ab8007ab..a030f71e95 100644
--- a/src/northbridge/amd/amdmct/wrappers/mcti_d.c
+++ b/src/northbridge/amd/amdmct/wrappers/mcti_d.c
@@ -396,14 +396,18 @@ static void mctHookAfterCPU(void)
 }
 
 
+#if IS_ENABLED(CONFIG_DIMM_DDR2)
 static void mctSaveDQSSigTmg_D(void)
 {
 }
+#endif
 
 
+#if IS_ENABLED(CONFIG_DIMM_DDR2)
 static void mctGetDQSSigTmg_D(void)
 {
 }
+#endif
 
 
 static void mctHookBeforeECC(void)