util: Add spd_tools to generate DDR4 SPDs for TGL boards

Serial Presence Detect (SPD) data for memory modules is used by Memory
Reference Code (MRC) for training the memory. This SPD data is
typically obtained from part vendors but has to be massaged to format
it correctly as per JEDEC and MRC expectations. There have been
numerous times in the past where the SPD data used is not always
correct.

In order to reduce the manual effort of creating SPDs and generating
DRAM IDs, this change adds tools for generating SPD files for DDR4
memory used in memory down configurations on Intel Tiger Lake (TGL)
based platforms. These tools generate SPDs following JESD79-4C and
Jedec "4.1.2.L-5 R29 v103" specification.

Two tools are provided:
* gen_spd.go: Generates de-duplicated SPD files using a global memory
  part list provided by the mainboard in JSON format. Additionally,
  generates a SPD manifest file (in CSV format) with information about
  what memory part from the global list uses which of the generated
  SPD files.

* gen_part_id.go: Allocates DRAM strap IDs for different DDR4
  memory parts used by the board. Takes as input list of memory parts
  used by the board (with one memory part on each line) and the SPD
  manifest file generated by gen_spd.go. Generates Makefile.inc for
  integrating the generated SPD files in the coreboot build.

BUG=b:160157545

Change-Id: I263f936b332520753a6791c8d892fc148cb6f103
Signed-off-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44429
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

4 files changed, 1913 insertions, 0 deletions

diff --git a/util/spd_tools/intel/ddr4/README.md b/util/spd_tools/intel/ddr4/README.md
new file mode 100644
index 0000000000..31e326d442
--- /dev/null
+++ b/util/spd_tools/intel/ddr4/README.md
@@ -0,0 +1,275 @@
+# DDR4 SPD tools README
+
+Tools for generating SPD files for DDR4 memory used in memory down
+configurations on Intel Tiger Lake (TGL) based
+platforms. These tools generate SPDs following JESD79-4C
+and Jedec 4.1.2.L-5 R29 v103 specifications.
+
+There are two tools provided that assist TGL based mainboards
+to generate SPDs and Makefile to integrate these SPDs in coreboot
+build. These tools can also be used to allocate DRAM IDs (configure
+DRAM hardware straps) for any DDR4 memory part used by the board.
+
+* gen_spd.go: Generates de-duplicated SPD files using a global memory
+  part list provided by the mainboard in JSON format. Additionally,
+  generates a SPD manifest file(in CSV format) with information about
+  what memory part from the global list uses which of the generated
+  SPD files.
+
+* gen_part_id.go: Allocates DRAM strap IDs for different DDR4
+  memory parts used by the board. Takes as input list of memory parts
+  used by the board (with one memory part on each line) and the SPD
+  manifest file generated by gen_spd.go. Generates Makefile.inc for
+  integrating the generated SPD files in the coreboot build.
+
+## Tool 1 - gen_spd.go
+
+This program takes as input:
+* Pointer to directory where the generated SPD files and manifest will
+  be placed.
+* JSON file containing a global list of memory parts with their
+  attributes as per the datasheet. This is the list of all known
+  DDR4 memory parts irrespective of their usage on the board.
+* SoC platform name for which the SPDs are being generated. Currently
+  supported platform names are `TGL`.
+
+Input JSON file requires the following two fields for every memory part:
+* `name`: Name of the memory part
+* `attribs`: List of attributes of the memory part as per its
+  datasheet. These attributes match the part specifications and are
+  independent of any SoC expectations. Tool takes care of translating
+  the physical attributes of the memory part to match JEDEC and Intel
+  MRC expectations.
+
+`attribs` field further contains two types of sub-fields:
+* Mandatory: These attributes have to be provided for a memory part.
+* Optional: These attributes can be provided by memory part if it wants
+  to override the defaults.
+
+### Mandatory `attribs`
+
+* `speedMTps`: Maximum rate supported by the part in MT/s. Valid values:
+  `1600, 1866, 2133, 2400, 2666, 2933, 3200` MT/s.
+
+* `CL_nRCD_nRP`: Refers to CAS Latency specified for the part (find
+  "CL-nRCD-nRP" in the vendor spec for the DDR4 part).
+
+* `capacityPerDieGb`: Capacity per die in gigabits.  Valid values:
+  `2, 4, 8, 16` Gb part.
+
+* `diesPerPackage`: Number of dies on the part.  Valid values:
+  `1, 2` dies per package.
+
+* `deviceBusWidth`: Number of bits of the device's address bus.  Valid values:
+  `8, 16` bit-wide bus. NOTE: Width of x4 is not supported by this tool.
+
+* `ranksPerPackage`: From Jedec doc 4_01_02_AnnexL-1R23:
+  “Package ranks per DIMM” refers to the collections of devices on the module
+  sharing common chip select signals (across the data width of the DIMM),
+  either from the edge connector for unbuffered modules or from the outputs of
+  a registering clock driver for RDIMMs and LRDIMMs.Number of bits of the
+  device's address bus.  Valid values:
+  `1, 2` package ranks.
+
+### Optional `attribs`
+
+The following options are calculated by the tool based on the mandatory
+attributes described for the part, but there may be cases where a default value
+must be overridden, such as when a device appears to be 3200AA, but does not
+support all of the CAS latencies typically supported by a speed bin 3200AA part.
+Do deal with such a case, the variable can be overridden here and the tool will
+use this value instead of calculating one.  All values must be defined in
+picosecond units, except for "CASLatencies", which would be represented as a
+string like "9 10 11 12 14".
+
+ * `TAAMinPs`: Defines the minimum CAS Latency.
+   Table 48 of Jedec doc 4_01_02_AnnexL-5R29 lists tAAmin for each speed grade.
+
+ * `TRASMinPs`: Refers to the minimum active to precharge delay time.
+   Table 55 of Jedec doc 4_01_02_AnnexL-5R29 lists tRPmin for each speed grade.
+
+ * `TCKMinPs`: Refers to the minimum clock cycle time.
+   Table 42 of Jedec doc 4_01_02_AnnexL-5R29 lists tCKmin for each speed grade.
+
+ * `TCKMaxPs`:Refers to the minimum clock cycle time.
+   Table 44 of Jedec doc 4_01_02_AnnexL-5R29 lists tCKmin for each speed grade.
+
+ * `TRFC1MinPs`: Refers to the minimum refresh recovery delay time.
+   Table 59 of Jedec doc 4_01_02_AnnexL-5R29 lists tRFC1min for each page size.
+
+ * `TRFC2MinPs`: Refers to the minimum refresh recovery delay time.
+   Table 61 of Jedec doc 4_01_02_AnnexL-5R29 lists tRFC2min for each page size.
+
+ * `TRFC4MinPs`: Refers to the minimum refresh recovery delay time.
+   Table 63 of Jedec doc 4_01_02_AnnexL-5R29 lists tRFC4min for each page size.
+
+ * `TFAWMinPs`:: Refers to the minimum four activate window delay time.
+   Table 66 of Jedec doc 4_01_02_AnnexL-5R29 lists tFAWmin for each speed grade
+   and page size combination.
+
+ * `TRRDSMinPs`: Refers to the minimum activate to activate delay time to
+   different bank groups.
+   Table 68 of Jedec doc 4_01_02_AnnexL-5R29 lists tRRD_Smin for each speed grade
+   and page size combination.
+
+ * `TRRDLMinPs`: Refers to the minimum activate to activate delay time to the
+   same bank group.
+   Table 70 of Jedec doc 4_01_02_AnnexL-5R29 lists tRRD_Lmin for each speed grade
+   and page size combination.
+
+ * `TCCDLMinPs`: Refers to the minimum CAS to CAS delay time to same bank group.
+   Table 72 of Jedec doc 4_01_02_AnnexL-5R29 lists tCCD_Lmin for each speed grade.
+
+ * `TWRMinPs`: Refers to the minimum write recovery time.
+   Table 75 of Jedec doc 4_01_02_AnnexL-5R29 lists tWRmin for each ddr4 type.
+
+ * `TWTRSMinPs`: Refers to minimum write to read time to different bank group.
+   Table 78 of Jedec doc 4_01_02_AnnexL-5R29 lists tWTR_Smin for each ddr4 type.
+
+ * `TWTRLMinPs`: Refers to minimum write to read time to same bank group.
+   Table 80 of Jedec doc 4_01_02_AnnexL-5R29 lists tWTR_Lmin for each ddr4 type.
+
+ * `CASLatencies`: Refers to the CAS latencies supported by the part.
+   The speed bin tables in the back of Jedec doc 4_01_02_AnnexL-5R29 define the
+   standard CAS latencies that a speed bin part is supposed to support.
+   In cases where a part does not support all of the CAS latencies listed in the
+   speed bin tables, this entry should be used to override the default settings.
+
+### Example JSON file
+```
+{
+    "parts": [
+        {
+            "name": "MEMORY_PART_A",
+            "attribs": {
+                "speedMTps": 3200,
+                "CL_nRCD_nRP": 22
+                "capacityPerDieGb": 8,
+                "diesPerPackage": 2,
+                "deviceBusWidth": 16,
+                "ranksPerPackage": 1,
+            }
+        },
+        {
+            "name": "MEMORY_PART_B",
+            "attribs": {
+                "speedMTps": 3200,
+                "CL_nRCD_nRP": 22
+                "capacityPerDieGb": 8,
+                "diesPerPackage": 1,
+                "deviceBusWidth": 16,
+                "ranksPerPackage": 2,
+                "casLatencies": "9 10 11 12 13 14 15 16 17 18 19 20",
+                "tCKMaxPs": "1250"
+            }
+        }
+    ]
+}
+```
+
+### Output
+
+This tool generates the following files using the global list of
+memory parts in JSON format as described above:
+  * De-duplicated SPDs required for the different memory parts. These
+    SPD files are named (ddr4-spd-1.hex, ddr4-spd-2.hex, and so on)
+    and placed in the directory provided as an input to the tool.
+  * CSV file representing which of the deduplicated SPD files is used
+    by which memory part. This file is named as
+    `spd_manifest.generated.txt` and placed in the directory provided
+    as an input to the tool along with the generated SPD
+    files. Example CSV file:
+    ```
+    MEMORY_PART_A, ddr4-spd-1.hex
+    MEMORY_PART_B, ddr4-spd-2.hex
+    MEMORY_PART_C, ddr4-spd-3.hex
+    MEMORY_PART_D, ddr4-spd-2.hex
+    MEMORY_PART_E, ddr4-spd-2.hex
+    ```
+
+## Tool 2 - gen_part_id.go
+
+This program takes as input:
+* Pointer to directory where the SPD files and the manifest file
+  `spd_manifest.generated.txt` (in CSV format) are placed by
+  gen_spd.go
+* File containing list of memory parts used by the board. Each line of
+  the file is supposed to contain one memory part `name` as present in
+  the global list of memory parts provided to gen_spd.go
+* Pointer to directory where the generated Makefile.inc should be
+  placed by the tool.
+
+### Output
+
+This program provides the following:
+
+* Prints out the list of DRAM hardware strap IDs that should be
+  allocated to each memory part listed in the input file.
+* Makefile.inc is generated in the provided directory to integrate
+  SPDs generated by gen_spd.go with the coreboot build for the board.
+* dram_id.generated.txt is generated in the same directory as
+  Makefile. This contains the part IDs assigned to the different
+  memory parts. (Useful to integrate in board schematics).
+
+Sample output (dram_id.generated.txt):
+```
+DRAM Part Name                 ID to assign
+MEMORY_PART_A                  0 (0000)
+MEMORY_PART_B                  1 (0001)
+MEMORY_PART_C                  2 (0010)
+MEMORY_PART_D                  1 (0001)
+```
+
+Sample Makefile.inc:
+```
+## SPDX-License-Identifier: GPL-2.0-or-later
+## This is an auto-generated file. Do not edit!!
+
+SPD_SOURCES =
+SPD_SOURCES += ddr4-spd-1.hex      # ID = 0(0b0000)  Parts = MEMORY_PART_A
+SPD_SOURCES += ddr4-spd-2.hex      # ID = 1(0b0001)  Parts = MEMORY_PART_B, MEMORY_PART_D
+SPD_SOURCES += ddr4-spd-3.hex      # ID = 2(0b0010)  Parts = MEMORY_PART_C
+```
+
+### Note of caution
+
+This program assigns DRAM IDs using the order of DRAM part names
+provided in the input file. Thus, when adding a new memory part to the
+list, it should always go to the end of the input text file. This
+guarantees that the memory parts that were already assigned IDs do not
+change.
+
+## How to build the tools?
+```
+# go build gen_spd.go
+# go build gen_part_id.go
+```
+
+## How to use the tools?
+```
+# ./gen_spd <spd_dir> <mem_parts_list_json> <platform>
+# ./gen_part_id <spd_dir> <makefile_dir> <mem_parts_used_file>
+```
+
+## Example Usage
+```
+# ./gen_spd ../../../../src/soc/intel/tigerlake/spd/ddr4 ./global_ddr4_mem_parts.json.txt 'TGL'
+
+```
+
+### Need to add a new memory part for a board?
+
+* If the memory part is not present in the global list of memory
+  parts, then add the memory part name and attributes as per the
+  datasheet to the file containing the global list.
+  * Use `gen_spd.go` with input as the file containing the global list
+    of memory parts to generate de-duplicated SPDs.
+  * If a new SPD file is generated, use `git add` to add it to the
+    tree and push a CL for review.
+* Update the file containing memory parts used by board (variant) to
+  add the new memory part name at the end of the file.
+  * Use gen_part_id.go providing it pointer to the location where SPD
+    files are stored and file containing the list of memory parts used
+    by the board(variant).
+  * Use `git add` to add `Makefile.inc` and `dram_id.generated.txt`
+    with updated changes and push a CL for review.
diff --git a/util/spd_tools/intel/ddr4/gen_part_id.go b/util/spd_tools/intel/ddr4/gen_part_id.go
new file mode 100644
index 0000000000..f67b4a9434
--- /dev/null
+++ b/util/spd_tools/intel/ddr4/gen_part_id.go
@@ -0,0 +1,215 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+package main
+
+import (
+	"encoding/csv"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+/*
+ * This program allocates DRAM strap IDs for different parts that are being used by the variant.
+ *
+ * It expects the following inputs:
+ *  Pointer to SPD directory. This is the location where SPD files and SPD Manifest generated by
+ *  gen_spd.go are placed.
+ *  Pointer to Makefile directory. Makefile.inc generated by this program is placed in this
+ *  location.
+ *  Text file containing a list of memory parts names used by the board. Each line in the file
+ *  is expected to have one memory part name.
+ */
+const (
+	SPDManifestFileName = "spd_manifest.generated.txt"
+	MakefileName = "Makefile.inc"
+	DRAMIdFileName = "dram_id.generated.txt"
+)
+
+func usage() {
+	fmt.Printf("\nUsage: %s <spd_dir> <makefile_dir> <mem_parts_used_file>\n\n", os.Args[0])
+	fmt.Printf("   where,\n")
+	fmt.Printf("   spd_dir = Directory path containing SPD files and manifest generated by gen_spd.go\n")
+	fmt.Printf("   makefile_dir = Directory path where generated Makefile.inc should be placed\n")
+	fmt.Printf("   mem_parts_used_file = File containing list of memory parts used by the board\n\n\n")
+}
+
+func checkArgs() error {
+
+	for _, arg := range os.Args[1:] {
+		if _, err := os.Stat(arg); err  != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+/*
+ * Read input file that contains list of memory part names used by the variant (one on a line)
+ * and split into separate strings for each part name.
+ */
+func readParts(memPartsUsedFileName string) ([]string, error) {
+	lines, err := ioutil.ReadFile(memPartsUsedFileName)
+	if err != nil {
+		return nil, err
+	}
+	str := string(lines)
+	parts := strings.Split(str, "\n")
+
+	return parts, nil
+}
+
+/*
+ * Read SPD manifest file(CSV) generated by gen_spd program and generate two maps:
+ * 1. Part to SPD Map : This maps global memory part name to generated SPD file name
+ * 2. SPD to Index Map: This generates a map of deduplicated SPD file names to index assigned to
+ *                      that SPD. This function sets index for all SPDs to -1. This index gets
+ *                      updated as part of genPartIdInfo() depending upon the SPDs actually used
+ *                      by the variant.
+ */
+func readSPDManifest(SPDDirName string) (map[string]string, map[string]int, error) {
+	f, err := os.Open(filepath.Join(SPDDirName, SPDManifestFileName))
+	if err != nil {
+		return nil, nil, err
+	}
+	defer f.Close()
+	r := csv.NewReader(f)
+
+	partToSPDMap := make(map[string]string)
+	SPDToIndexMap := make(map[string]int)
+
+	for {
+		fields, err := r.Read()
+
+		if err == io.EOF {
+			break
+		}
+
+		if err != nil {
+			return nil, nil, err
+		}
+
+		if len(fields) != 2 {
+			return nil, nil, fmt.Errorf("CSV file is incorrectly formatted")
+		}
+
+		partToSPDMap[fields[0]] = fields[1]
+		SPDToIndexMap[fields[1]] = -1
+	}
+
+	return partToSPDMap, SPDToIndexMap, nil
+}
+
+/* Print information about memory part used by variant and ID assigned to it. */
+func appendPartIdInfo(s *string, partName string, index int) {
+	*s += fmt.Sprintf("%-30s %d (%04b)\n", partName, index, int64(index))
+}
+
+type partIds struct {
+	SPDFileName string
+	memParts string
+}
+
+/*
+ * For each part used by variant, check if the SPD (as per the manifest) already has an ID
+ * assigned to it. If yes, then add the part name to the list of memory parts supported by the
+ * SPD entry. If not, then assign the next ID to the SPD file and add the part name to the
+ * list of memory parts supported by the SPD entry.
+ *
+ * Returns list of partIds that contains spdFileName and supported memory parts for each
+ * assigned ID.
+ */
+func genPartIdInfo(parts []string, partToSPDMap map[string]string, SPDToIndexMap map[string]int, makefileDirName string) ([]partIds, error) {
+	partIdList := []partIds{}
+	curId := 0
+	var s string
+
+	s += fmt.Sprintf("%-30s %s\n", "DRAM Part Name", "ID to assign")
+
+	for _, p := range parts {
+		if p == "" {
+			continue
+		}
+
+		SPDFileName,ok := partToSPDMap[p]
+		if !ok {
+			return nil, fmt.Errorf("Failed to find part ", p, " in SPD Manifest. Please add the part to global part list and regenerate SPD Manifest")
+		}
+
+		index := SPDToIndexMap[SPDFileName]
+		if index != -1 {
+			partIdList[index].memParts += ", " + p
+			appendPartIdInfo(&s, p, index)
+			continue
+		}
+
+		SPDToIndexMap[SPDFileName] = curId
+
+		appendPartIdInfo(&s, p, curId)
+		entry := partIds{SPDFileName: SPDFileName, memParts: p}
+		partIdList = append(partIdList, entry)
+
+		curId++
+	}
+
+	fmt.Printf("%s", s)
+	err := ioutil.WriteFile(filepath.Join(makefileDirName, DRAMIdFileName), []byte(s), 0644)
+
+	return partIdList, err
+}
+
+var generatedCodeLicense string = "## SPDX-License-Identifier: GPL-2.0-or-later"
+var autoGeneratedInfo string = "## This is an auto-generated file. Do not edit!!"
+
+/*
+ * This function generates Makefile.inc under the variant directory path and adds assigned SPDs
+ * to SPD_SOURCES.
+ */
+func genMakefile(partIdList []partIds, makefileDirName string) error {
+	var s string
+
+	s += fmt.Sprintf("%s\n%s\n\n", generatedCodeLicense, autoGeneratedInfo)
+	s += fmt.Sprintf("MEMORY_TYPE = ddr4\n\n")
+	s += fmt.Sprintf("SPD_SOURCES =\n")
+
+	for i := 0; i < len(partIdList); i++ {
+		s += fmt.Sprintf("SPD_SOURCES += %s ", partIdList[i].SPDFileName)
+		s += fmt.Sprintf("     # ID = %d(0b%04b) ", i, int64(i))
+		s += fmt.Sprintf(" Parts = %04s\n", partIdList[i].memParts)
+	}
+
+	return ioutil.WriteFile(filepath.Join(makefileDirName, MakefileName), []byte(s), 0644)
+}
+
+func main() {
+	if len(os.Args) != 4 {
+		usage()
+		log.Fatal("Incorrect number of arguments")
+	}
+
+	SPDDir, MakefileDir, MemPartsUsedFile := os.Args[1], os.Args[2], os.Args[3]
+
+	partToSPDMap, SPDToIndexMap, err := readSPDManifest(SPDDir)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	parts, err := readParts(MemPartsUsedFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	partIdList, err := genPartIdInfo(parts, partToSPDMap, SPDToIndexMap, MakefileDir)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if err := genMakefile(partIdList, MakefileDir); err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/util/spd_tools/intel/ddr4/gen_spd.go b/util/spd_tools/intel/ddr4/gen_spd.go
new file mode 100644
index 0000000000..5adadc962a
--- /dev/null
+++ b/util/spd_tools/intel/ddr4/gen_spd.go
@@ -0,0 +1,1386 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+/*
+ * This program generates de-duplicated SPD files for DDR4 memory using the global memory
+ * part list provided in CSV format. In addition to that, it also generates SPD manifest in CSV
+ * format that contains entries of type (DRAM part name, SPD file name) which provides the SPD
+ * file name used by a given DRAM part.
+ *
+ * It takes as input:
+ * Pointer to directory where the generated SPD files will be placed.
+ * JSON file containing a list of memory parts with their attributes as per datasheet.
+ */
+const (
+	SPDManifestFileName = "spd_manifest.generated.txt"
+
+	PlatformTGL = 0
+)
+
+var platformMap = map[string]int {
+	"TGL": PlatformTGL,
+}
+
+var currPlatform int
+
+type memAttributes struct {
+	/* Primary attributes - must be provided by JSON file for each part */
+	SpeedMTps int
+	CL_nRCD_nRP int
+	CapacityPerDieGb int
+	DiesPerPackage int
+	DeviceBusWidth  int
+	RanksPerPackage int
+
+	/*
+         * All the following parameters are optional and required only if the part requires
+         * special parameters as per the datasheet.
+         */
+        /* Timing parameters */
+	TAAMinPs int
+	TRCDMinPs int
+	TRPMinPs int
+	TRASMinPs int
+	TRCMinPs int
+	TCKMinPs int
+	TCKMaxPs int
+	TRFC1MinPs int
+	TRFC2MinPs int
+	TRFC4MinPs int
+	TFAWMinPs int
+	TRRDLMinPs int
+	TRRDSMinPs int
+	TCCDLMinPs int
+	TWRMinPs int
+	TWTRLMinPs int
+	TWTRSMinPs int
+
+	/* CAS */
+	CASLatencies string
+	CASFirstByte byte
+	CASSecondByte byte
+	CASThirdByte byte
+	CASFourthByte byte
+}
+
+/* This encodes the density in Gb to SPD low nibble value as per JESD 4.1.2.L-5 R29 */
+var densityGbToSPDEncoding = map[int]byte {
+	2: 0x3,
+	4: 0x4,
+	8: 0x5,
+	16: 0x6,
+}
+
+/*
+ * Tables 4 thru Table 7 from JESD79-4C.
+ * Maps density per die to row-column encoding for a device with x8/x16
+ * physical channel.
+ */
+var densityGbx8x16DieCapacityToRowColumnEncoding = map[int]byte {
+	2: 0x11, /* 14 rows, 10 columns */
+	4: 0x19, /* 15 rows, 10 columns */
+	8: 0x21, /* 16 rows, 10 columns */
+	16: 0x29, /* 17 rows, 10 columns */
+}
+
+/*
+ * Tables 169 & 170 in the JESD79-4C spec
+ * Maps die density to refresh timings. This is the same for x8 and x16
+ * devices.
+ */
+
+/* maps die density to rcf1 timing in pico seconds */
+var tRFC1Encoding = map[int]int {
+	2: 160000,
+	4: 260000,
+	8: 350000,
+	16: 550000,
+}
+
+/* maps die density to rcf2 timing in pico seconds */
+var tRFC2Encoding = map[int]int {
+	2: 110000,
+	4: 160000,
+	8: 260000,
+	16: 350000,
+}
+
+/* maps die density to rcf4 timing in pico seconds */
+var tRFC4Encoding = map[int]int {
+	2: 90000,
+	4: 110000,
+	8: 160000,
+	16: 260000,
+}
+
+func getTRCMinPs(memAttribs *memAttributes) int {
+	return memAttribs.TAAMinPs + memAttribs.TRASMinPs
+}
+
+func getDefaultTCKMinPs(memAttribs *memAttributes) int {
+	/* value 2000000 = 2 * 1000000, where 1000000 is to convert mS to pS */
+	return 2000000 / memAttribs.SpeedMTps
+}
+
+type speedBinAttributes struct {
+	TRASMinPs int
+	TCKMaxPs int
+}
+
+var speedBinToSPDEncoding = map[int]speedBinAttributes {
+	1600: {
+		TRASMinPs: 35000,
+		TCKMaxPs: 1500,
+	},
+	1866: {
+		TRASMinPs: 34000,
+		TCKMaxPs: 1250,
+	},
+	2133: {
+		TRASMinPs: 33000,
+		TCKMaxPs: 1071,
+	},
+	2400: {
+		TRASMinPs: 32000,
+		TCKMaxPs: 937,
+	},
+	2666: {
+		TRASMinPs: 32000,
+		TCKMaxPs: 833,
+	},
+	2933: {
+		TRASMinPs: 32000,
+		TCKMaxPs: 750,
+	},
+	3200: {
+		TRASMinPs: 32000,
+		TCKMaxPs: 682,
+	},
+}
+
+func getBankGroups(memAttribs *memAttributes) byte {
+	var bg byte
+
+	switch memAttribs.DeviceBusWidth {
+	case 8:
+		bg = 4
+	case 16:
+		if memAttribs.DiesPerPackage == 1 {
+			bg = 2 /* x16 SDP has 2 bank groups */
+		} else {
+			bg = 4 /* x16 DDP has 4 bank groups */
+		}
+	}
+
+	return bg
+}
+
+func encodeBankGroups(bg byte) byte {
+	var val byte
+
+	switch bg {
+	case 2:
+		val = 1
+	case 4:
+		val = 2
+	}
+
+	return val << 6
+}
+
+func encodeDensityBanks(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = densityGbToSPDEncoding[memAttribs.CapacityPerDieGb]
+	b |= encodeBankGroups(getBankGroups(memAttribs))
+	/* No need to encode banksPerGroup.it's always 4 ([4:5] = 0) */
+
+	return b
+}
+
+func encodeSdramAddressing(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = densityGbx8x16DieCapacityToRowColumnEncoding[memAttribs.CapacityPerDieGb]
+
+	return b
+}
+
+func encodePackageDeviceType(dies int) byte {
+	var b byte
+
+	if dies > 1 {
+		/* If more than one die, then this is a non-monolithic device. */
+		b = 1
+	} else {
+		/* If only single die, then this is a monolithic device. */
+		b = 0
+	}
+
+	return b << 7
+}
+
+func encodeSignalLoadingFromDieCount(dies int) byte {
+	var loading byte
+
+	/*
+	 * If die count = 1, signal loading = "not specified" = 0
+	 * If die count > 1, signal loading = "multi" = 2
+	 */
+	if dies == 1 {
+		loading = 0
+	} else {
+		loading = 1
+	}
+
+	return loading
+}
+
+func encodeDiesPerPackage(dies int) byte {
+	var b byte
+
+	b = encodePackageDeviceType(dies) /* Monolithic / Non-monolithic device */
+	b |= (byte(dies) - 1) << 4
+
+	return b
+}
+
+func encodePackageType(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = encodeDiesPerPackage(memAttribs.DiesPerPackage)
+	b |= encodeSignalLoadingFromDieCount(memAttribs.DiesPerPackage)
+
+	return b
+}
+
+func encodeDataWidth(bitWidthPerDevice int) byte {
+	var width byte
+
+	switch bitWidthPerDevice {
+	case 8:
+		width = 1
+	case 16:
+		width = 2
+	}
+
+	return width
+}
+
+func encodeRanks(ranks int) byte {
+	var b byte
+
+	b = byte(ranks - 1)
+
+	return b << 3
+}
+
+func encodeModuleOrganization(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = encodeDataWidth(memAttribs.DeviceBusWidth)
+	b |= encodeRanks(memAttribs.RanksPerPackage)
+
+	return b
+}
+
+func encodeTCKMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TCKMinPs)
+}
+
+func encodeTCKMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TCKMinPs)
+}
+
+func encodeTCKMax(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TCKMaxPs)
+}
+
+func encodeTCKMaxFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TCKMaxPs)
+}
+
+func divRoundUp(dividend int, divisor int) int {
+	return (dividend + divisor - 1) / divisor
+}
+
+func convNsToPs(timeNs int) int {
+	return timeNs * 1000
+}
+
+func convMtbToPs(mtb int) int {
+	return mtb * 125
+}
+
+func convPsToMtb(timePs int) int {
+	return divRoundUp(timePs, 125)
+}
+
+func convPsToMtbByte(timePs int) byte {
+	return byte(convPsToMtb(timePs) & 0xff)
+}
+
+func convPsToFtbByte(timePs int) byte {
+	mtb := convPsToMtb(timePs)
+	ftb := timePs - convMtbToPs(mtb)
+
+	return byte(ftb)
+}
+
+func encodeTAAMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TAAMinPs)
+}
+
+func encodeTAAMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TAAMinPs)
+}
+
+func encodeTRCDMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TRCDMinPs)
+}
+
+func encodeTRCDMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TRCDMinPs)
+}
+
+func encodeTRPMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TRPMinPs)
+}
+
+func encodeTRCMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TRCMinPs)
+}
+
+func encodeTRPMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TRPMinPs)
+}
+
+func encodeTRASRCMinMSNs(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = byte((convPsToMtb(memAttribs.TRASMinPs) >> 4) & 0xf0)
+	b |= byte((convPsToMtb(memAttribs.TRCMinPs) >> 8) & 0x0f)
+
+	return b
+}
+
+func encodeTRASMinLsb(memAttribs *memAttributes) byte {
+	return byte(convPsToMtb(memAttribs.TRASMinPs) & 0xff)
+}
+
+func encodeTRCMinLsb(memAttribs *memAttributes) byte {
+	return byte(convPsToMtb(memAttribs.TRCMinPs) & 0xff)
+}
+
+var pageSizefromBusWidthEncoding = map[int]int {
+	8: 1,
+	16: 2,
+}
+
+/*
+ * Per Table 69 & Table 70 of Jedec JESD79-4C
+ * tFAW timing is based on :
+ *  Speed bin and page size
+ */
+func getTFAWMinPs(memAttribs *memAttributes) int {
+	var tFAWFixed int
+
+	if pageSizefromBusWidthEncoding[memAttribs.DeviceBusWidth] == 1 {
+		switch memAttribs.SpeedMTps {
+		case 1600:
+			tFAWFixed = 25000
+		case 1866:
+			tFAWFixed = 23000
+		default:
+			tFAWFixed = 21000
+		}
+	} else if pageSizefromBusWidthEncoding[memAttribs.DeviceBusWidth] == 2 {
+		switch memAttribs.SpeedMTps {
+		case 1600:
+			tFAWFixed = 35000
+		default:
+			tFAWFixed = 30000
+		}
+	}
+
+	return tFAWFixed
+}
+
+/* Update settings based on data sheet (json) supplied memory attributes */
+
+func updateTFAWMin(memAttribs *memAttributes) {
+	var tFAWFromTck int
+
+	if memAttribs.TFAWMinPs == 0 {
+		memAttribs.TFAWMinPs = getTFAWMinPs(memAttribs)
+	}
+
+	switch pageSizefromBusWidthEncoding[memAttribs.DeviceBusWidth] {
+	case 1:
+		tFAWFromTck = 20 * memAttribs.TCKMinPs
+	case 2:
+		tFAWFromTck = 28 * memAttribs.TCKMinPs
+	}
+
+	if memAttribs.TFAWMinPs < tFAWFromTck {
+		memAttribs.TFAWMinPs = tFAWFromTck
+	}
+}
+
+func updateTRFC1Min(memAttribs *memAttributes) {
+	if memAttribs.TRFC1MinPs == 0 {
+		memAttribs.TRFC1MinPs = tRFC1Encoding[memAttribs.CapacityPerDieGb]
+	}
+}
+
+func updateTRFC2Min(memAttribs *memAttributes) {
+	if memAttribs.TRFC2MinPs == 0 {
+		memAttribs.TRFC2MinPs = tRFC2Encoding[memAttribs.CapacityPerDieGb]
+	}
+}
+
+func updateTRFC4Min(memAttribs *memAttributes) {
+	if memAttribs.TRFC4MinPs == 0 {
+		memAttribs.TRFC4MinPs = tRFC4Encoding[memAttribs.CapacityPerDieGb]
+	}
+}
+
+func getTRRDLMinPs(memAttribs *memAttributes) int {
+	var tRRDLFixed int
+
+	/*
+	 * Per JESD79-4C Tables 169 & 170, tRRD_L is based on :
+	 *  Speed bin and page size
+	 */
+	switch pageSizefromBusWidthEncoding[memAttribs.DeviceBusWidth] {
+	case 1:
+		switch memAttribs.SpeedMTps {
+		case 1600:
+			tRRDLFixed = 6000
+		default:
+			tRRDLFixed = 5300
+		}
+	case 2:
+		switch memAttribs.SpeedMTps {
+		case 1600:
+			tRRDLFixed = 7500
+		default:
+			tRRDLFixed = 6400
+		}
+	}
+
+	return tRRDLFixed
+}
+
+func updateTRRDLMin(memAttribs *memAttributes) {
+	var tRRDLFromTck int
+
+	if memAttribs.TRRDLMinPs == 0 {
+		memAttribs.TRRDLMinPs= getTRRDLMinPs(memAttribs)
+	}
+
+	tRRDLFromTck = 4 * memAttribs.TCKMinPs
+
+	if memAttribs.TRRDLMinPs < tRRDLFromTck {
+		memAttribs.TRRDLMinPs = tRRDLFromTck
+	}
+}
+
+var speedToTRRDSMinPsOneKPageSize = map[int]int {
+	1600: 5000,
+	1866: 4200,
+	2133: 3700,
+	2400: 3300,
+	2666: 3000,
+	2933: 2700,
+	3200: 2500,
+}
+
+var speedToTRRDSMinPsTwoKPageSize = map[int]int {
+	1600: 6000,
+	1866: 5300,
+	2133: 5300,
+	2400: 5300,
+	2666: 5300,
+	2933: 5300,
+	3200: 5300,
+}
+
+func getTRRDSMinPs(memAttribs *memAttributes) int {
+	var tRRDFixed int
+
+	switch pageSizefromBusWidthEncoding[memAttribs.DeviceBusWidth] {
+	case 1:
+		tRRDFixed = speedToTRRDSMinPsOneKPageSize[memAttribs.SpeedMTps]
+	case 2:
+		tRRDFixed = speedToTRRDSMinPsTwoKPageSize[memAttribs.SpeedMTps]
+	}
+
+	return tRRDFixed
+}
+
+func updateTRRDSMin(memAttribs *memAttributes) {
+	var tRRDFromTck int
+
+	if memAttribs.TRRDSMinPs == 0 {
+		memAttribs.TRRDSMinPs = getTRRDSMinPs(memAttribs)
+	}
+
+	tRRDFromTck = 4 * memAttribs.TCKMinPs
+
+	if memAttribs.TRRDSMinPs < tRRDFromTck {
+		memAttribs.TRRDSMinPs = tRRDFromTck
+	}
+}
+
+/*
+ * Per JESD79-4C Tables 169 and 170,
+ * tCCD_L is based on :
+ *  Speed Bin
+ */
+func getTCCDLMinPs(memAttribs *memAttributes) int {
+	var tCCDLFixed int
+
+	switch memAttribs.SpeedMTps {
+        case 1600:
+		tCCDLFixed = 6250
+        case 1866:
+		tCCDLFixed = 5355
+        case 2133:
+		tCCDLFixed = 5355
+	default:
+		tCCDLFixed = 5000
+	}
+
+	return tCCDLFixed
+}
+
+func updateTCCDLMin(memAttribs *memAttributes) {
+	var tCCDLFromTck int
+
+	if memAttribs.TCCDLMinPs == 0 {
+		memAttribs.TCCDLMinPs = getTCCDLMinPs(memAttribs)
+	}
+
+	tCCDLFromTck = 5 * memAttribs.TCKMinPs
+
+	if memAttribs.TCCDLMinPs < tCCDLFromTck {
+		memAttribs.TCCDLMinPs = tCCDLFromTck
+	}
+}
+
+func encodeTRFC1MinLsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC1MinPs)
+
+	return byte(mtb & 0xff)
+}
+
+func encodeTRFC1MinMsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC1MinPs)
+
+	return byte((mtb >> 8) & 0xff)
+}
+
+func encodeTRFC2MinLsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC2MinPs)
+
+	return byte(mtb & 0xff)
+}
+
+func encodeTRFC2MinMsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC2MinPs)
+
+	return byte((mtb >> 8) & 0xff)
+}
+
+func encodeTRFC4MinLsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC4MinPs)
+
+	return byte(mtb & 0xff)
+}
+
+func encodeTRFC4MinMsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TRFC4MinPs)
+
+	return byte((mtb >> 8) & 0xff)
+}
+
+func encodeTFAWMinMSN(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TFAWMinPs)
+
+	return byte((mtb >> 8) & 0x0f)
+}
+
+func encodeTFAWMinLsb(memAttribs *memAttributes) byte {
+	var mtb int
+
+	mtb = convPsToMtb(memAttribs.TFAWMinPs)
+
+	return byte(mtb & 0xff)
+}
+
+func encodeCASFirstByte(memAttribs *memAttributes) byte {
+	return memAttribs.CASFirstByte
+}
+
+func encodeCASSecondByte(memAttribs *memAttributes) byte {
+	return memAttribs.CASSecondByte
+}
+
+func encodeCASThirdByte(memAttribs *memAttributes) byte {
+	return memAttribs.CASThirdByte
+}
+
+func encodeCASFourthByte(memAttribs *memAttributes) byte {
+	return memAttribs.CASFourthByte
+}
+
+func encodeTRRDSMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TRRDSMinPs)
+}
+
+func encodeTRRDSMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TRRDSMinPs)
+}
+
+func encodeTRRDLMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TRRDLMinPs)
+}
+
+func encodeTRRDLMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TRRDLMinPs)
+}
+
+func encodeTCCDLMin(memAttribs *memAttributes) byte {
+	return convPsToMtbByte(memAttribs.TCCDLMinPs)
+}
+
+func encodeTCCDLMinFineOffset(memAttribs *memAttributes) byte {
+	return convPsToFtbByte(memAttribs.TCCDLMinPs)
+}
+
+func encodeTWRMinMSN(memAttribs *memAttributes) byte {
+	return byte((convPsToMtb(TimingValueTWRMinPs) >> 8) & 0x0f)
+}
+
+func encodeTWRMinLsb(memAttribs *memAttributes) byte {
+	return byte(convPsToMtb(TimingValueTWRMinPs) & 0xff)
+}
+
+func encodeTWTRMinMSNs(memAttribs *memAttributes) byte {
+	var b byte
+
+	b = byte((convPsToMtb(memAttribs.TWTRLMinPs) >> 4) & 0xf0)
+	b |= byte((convPsToMtb(memAttribs.TWTRSMinPs) >> 8) & 0x0f)
+
+	return b
+}
+
+func encodeTWTRSMinLsb(memAttribs *memAttributes) byte {
+	return byte(convPsToMtb(memAttribs.TWTRSMinPs) & 0xff)
+}
+
+func encodeTWTRLMinLsb(memAttribs *memAttributes) byte {
+	return byte(convPsToMtb(memAttribs.TWTRLMinPs) & 0xff)
+}
+
+type SPDMemAttribFunc func (*memAttributes) byte
+type SPDConvConstFunc func () byte
+
+type SPDAttribTableEntry struct {
+	constVal byte
+	getVal SPDMemAttribFunc
+}
+
+const (
+	/* SPD Byte Index */
+	SPDIndexSize = 0
+	SPDIndexRevision = 1
+	SPDIndexMemoryType = 2
+	SPDIndexModuleType = 3
+	SPDIndexDensityBanks = 4
+	SPDIndexAddressing = 5
+	SPDIndexPackageType = 6
+	SPDIndexOptionalFeatures = 7
+	SPDIndexModuleOrganization = 12
+	SPDIndexBusWidth = 13
+	SPDIndexTimebases = 17
+	SPDIndexTCKMin = 18
+	SPDIndexTCKMax = 19
+	SPDIndexCASFirstByte = 20
+	SPDIndexCASSecondByte = 21
+	SPDIndexCASThirdByte = 22
+	SPDIndexCASFourthByte = 23
+	SPDIndexTAAMin = 24
+	SPDIndexTRCDMin = 25
+	SPDIndexTRPMin = 26
+	SPDIndexTRASRCMinMSNs = 27
+	SPDIndexTRASMinLsb = 28
+	SPDIndexTRCMinLsb = 29
+	SPDIndexTRFC1MinLsb = 30
+	SPDIndexTRFC1MinMsb = 31
+	SPDIndexTRFC2MinLsb = 32
+	SPDIndexTRFC2MinMsb = 33
+	SPDIndexTRFC4MinLsb = 34
+	SPDIndexTRFC4MinMsb = 35
+	SPDIndexTFAWMinMSN = 36
+	SPDIndexTFAWMinLsb = 37
+	SPDIndexTRRDSMin = 38
+	SPDIndexTRRDLMin = 39
+	SPDIndexTCCDLMin = 40
+	SPDIndexTWRMinMSN = 41
+	SPDIndexTWRMinLsb = 42
+	SPDIndexTWTRMinMSNs = 43
+	SPDIndexWTRSMinLsb = 44
+	SPDIndexWTRLMinLsb = 45
+	SPDIndexTCCDLMinFineOffset = 117
+	SPDIndexTRRDLMinFineOffset = 118
+	SPDIndexTRRDSMinFineOffset = 119
+	SPDIndexTRCMinFineOffset = 120
+	SPDIndexTRPMinFineOffset = 121
+	SPDIndexTRCDMinFineOffset = 122
+	SPDIndexTAAMinFineOffset = 123
+	SPDIndexTCKMaxFineOffset = 124
+	SPDIndexTCKMinFineOffset = 125
+	SPDIndexManufacturerPartNumberStartByte = 329
+	SPDIndexManufacturerPartNumberEndByte = 348
+
+	/* SPD Byte Value */
+
+	/*
+	 * From JEDEC spec:
+	 * 6:4 (Bytes total) = 2 (512 bytes)
+	 * 3:0 (Bytes used) = 3 (384 bytes)
+	 * Set to 0x23 for DDR4.
+	 */
+	SPDValueSize = 0x23
+
+	/*
+	 * From JEDEC spec: Revision 1.1
+	 * Set to 0x11.
+	 */
+	SPDValueRevision = 0x11
+
+	/* DDR4 memory type = 0x0C */
+	SPDValueMemoryType = 0x0C
+
+	/*
+	 * From JEDEC spec:
+ 	 * Module Type [0:3] :
+	 *  0 = Undefined
+	 *  1 = RDIMM (width = 133.35 mm nom)
+	 *  2 = UDIMM (width = 133.35 mm nom)
+	 *  3 = SO-DIMM (width = 68.60 mm nom)
+	 *  4 = LRDIMM (width = 133.35 mm nom)
+	 *
+	 * DDR4 on TGL uses SO-DIMM type for for both memory down and DIMM config.
+	 * Set to 0x03.
+	 */
+	SPDValueModuleType = 0x03
+
+	/*
+	 * From JEDEC spec:
+	 * 5:4 (Maximum Activate Window) = 00 (8192 * tREFI)
+	 * 3:0 (Maximum Activate Count) = 1000 (Unlimited MAC)
+	 *
+	 * Needs to come from datasheet, but most parts seem to support unlimited MAC.
+	 * MR#24 OP3
+	 */
+	SPDValueOptionalFeatures = 0x08
+
+	/*
+	 * From JEDEC spec:
+	 * 2:0 Primary Bus Width in Bits = 011 (x64 always)
+	 * Set to 0x03.
+	 */
+	SPDValueModuleBusWidth = 0x03
+
+	/*
+	 * From JEDEC spec:
+	 * 3:2 (MTB) = 00 (0.125ns)
+	 * 1:0 (FTB) = 00 (1ps)
+	 * Set to 0x00.
+	 */
+	SPDValueTimebases = 0x00
+
+	/* CAS fourth byte: All bits are reserved */
+	SPDValueCASFourthByte = 0x00
+
+	/* As per JEDEC spec, unused digits of manufacturer part number are left as blank. */
+	SPDValueManufacturerPartNumberBlank = 0x20
+
+)
+
+const (
+	/*
+	 * As per Table 75 of Jedec spec 4.1.20-L-5 R29 v103:
+	 * tWRMin = 15nS for all DDR4 Speed Bins
+	 * Set to 15000 pS
+	 */
+	 TimingValueTWRMinPs = 15000
+
+	/*
+	 * As per Table 78 of Jedec spec 4.1.20-L-5 R29 v103:
+	 * tWTR_SMin = 2.5nS for all DDR4 Speed Bins
+	 * Set to 2500 pS
+	 */
+	 TimingValueTWTRSMinPs = 2500
+
+	/*
+	 * As per Table 80 of Jedec spec 4.1.20-L-5 R29 v103:
+	 * tWTR_LMin = 7.5 nS for all DDR4 Speed Bins
+	 * Set to 7500 pS
+	 */
+	 TimingValueTWTRLMinPs = 7500
+)
+
+var SPDAttribTable = map[int]SPDAttribTableEntry {
+	SPDIndexSize: { constVal: SPDValueSize },
+	SPDIndexRevision: { constVal: SPDValueRevision },
+	SPDIndexMemoryType: { constVal: SPDValueMemoryType },
+	SPDIndexModuleType: { constVal: SPDValueModuleType },
+	SPDIndexDensityBanks: { getVal: encodeDensityBanks },
+	SPDIndexAddressing: { getVal: encodeSdramAddressing },
+	SPDIndexPackageType: { getVal: encodePackageType },
+	SPDIndexOptionalFeatures: { constVal: SPDValueOptionalFeatures },
+	SPDIndexModuleOrganization: { getVal: encodeModuleOrganization },
+	SPDIndexBusWidth: { constVal: SPDValueModuleBusWidth },
+	SPDIndexTimebases: { constVal: SPDValueTimebases },
+	SPDIndexTCKMin: { getVal: encodeTCKMin },
+	SPDIndexTCKMinFineOffset: { getVal: encodeTCKMinFineOffset },
+	SPDIndexTCKMax: { getVal: encodeTCKMax },
+	SPDIndexTCKMaxFineOffset: { getVal: encodeTCKMaxFineOffset },
+	SPDIndexCASFirstByte: { getVal: encodeCASFirstByte },
+	SPDIndexCASSecondByte: { getVal: encodeCASSecondByte },
+	SPDIndexCASThirdByte: { getVal: encodeCASThirdByte },
+	SPDIndexCASFourthByte: { getVal: encodeCASFourthByte },
+	SPDIndexTAAMin: { getVal: encodeTAAMin },
+	SPDIndexTAAMinFineOffset: { getVal: encodeTAAMinFineOffset },
+	SPDIndexTRCDMin: { getVal: encodeTRCDMin },
+	SPDIndexTRCDMinFineOffset: { getVal: encodeTRCDMinFineOffset },
+	SPDIndexTRPMin: { getVal: encodeTRPMin },
+	SPDIndexTRPMinFineOffset: { getVal: encodeTRPMinFineOffset },
+	SPDIndexTRASRCMinMSNs: { getVal: encodeTRASRCMinMSNs },
+	SPDIndexTRASMinLsb: { getVal: encodeTRASMinLsb },
+	SPDIndexTRCMinLsb: { getVal: encodeTRCMinLsb },
+	SPDIndexTRCMinFineOffset: { getVal: encodeTRCMinFineOffset },
+	SPDIndexTRFC1MinLsb: { getVal: encodeTRFC1MinLsb },
+	SPDIndexTRFC1MinMsb: { getVal: encodeTRFC1MinMsb },
+	SPDIndexTRFC2MinLsb: { getVal: encodeTRFC2MinLsb },
+	SPDIndexTRFC2MinMsb: { getVal: encodeTRFC2MinMsb },
+	SPDIndexTRFC4MinLsb: { getVal: encodeTRFC4MinLsb },
+	SPDIndexTRFC4MinMsb: { getVal: encodeTRFC4MinMsb },
+	SPDIndexTFAWMinMSN: { getVal: encodeTFAWMinMSN },
+	SPDIndexTFAWMinLsb: { getVal: encodeTFAWMinLsb },
+	SPDIndexTRRDSMin: { getVal: encodeTRRDSMin },
+	SPDIndexTRRDSMinFineOffset: { getVal: encodeTRRDSMinFineOffset },
+	SPDIndexTRRDLMin: { getVal: encodeTRRDLMin },
+	SPDIndexTRRDLMinFineOffset: { getVal: encodeTRRDLMinFineOffset },
+	SPDIndexTCCDLMin: { getVal: encodeTCCDLMin },
+	SPDIndexTCCDLMinFineOffset: { getVal: encodeTCCDLMinFineOffset },
+	SPDIndexTWRMinMSN: { getVal: encodeTWRMinMSN },
+	SPDIndexTWRMinLsb: { getVal: encodeTWRMinLsb },
+	SPDIndexTWTRMinMSNs: { getVal: encodeTWTRMinMSNs },
+	SPDIndexWTRSMinLsb: { getVal: encodeTWTRSMinLsb },
+	SPDIndexWTRLMinLsb: { getVal: encodeTWTRLMinLsb },
+}
+
+type memParts struct {
+	MemParts []memPart `json:"parts"`
+}
+
+type memPart struct {
+	Name string
+	Attribs memAttributes
+	SPDFileName string
+}
+
+func writeSPDManifest(memParts *memParts, SPDDirName string) error {
+	var s string
+
+	fmt.Printf("Generating SPD Manifest with following entries:\n")
+
+	for i := 0; i < len(memParts.MemParts); i++ {
+		fmt.Printf("%-40s %s\n", memParts.MemParts[i].Name, memParts.MemParts[i].SPDFileName)
+		s += fmt.Sprintf("%s,%s\n", memParts.MemParts[i].Name, memParts.MemParts[i].SPDFileName)
+	}
+
+	return ioutil.WriteFile(filepath.Join(SPDDirName, SPDManifestFileName), []byte(s), 0644)
+}
+
+func isManufacturerPartNumberByte(index int) bool {
+	if index >= SPDIndexManufacturerPartNumberStartByte && index <= SPDIndexManufacturerPartNumberEndByte {
+		return true
+	}
+	return false
+}
+
+
+func getSPDByte(index int, memAttribs *memAttributes) byte {
+	e, ok := SPDAttribTable[index]
+	if ok == false {
+		if isManufacturerPartNumberByte(index) {
+			return SPDValueManufacturerPartNumberBlank
+		}
+		return 0x00
+	}
+
+	if e.getVal != nil {
+		return e.getVal(memAttribs)
+	}
+
+	return e.constVal
+}
+
+func createSPD(memAttribs *memAttributes) string {
+	var s string
+
+	for i := 0; i < 512; i++ {
+		b := getSPDByte(i, memAttribs)
+
+		if (i + 1) % 16 == 0 {
+			s += fmt.Sprintf("%02X\n", b)
+		} else {
+			s += fmt.Sprintf("%02X ", b)
+		}
+	}
+
+	return s
+}
+
+func dedupeMemoryPart(dedupedParts []*memPart, memPart *memPart) bool {
+	for i := 0; i < len(dedupedParts); i++ {
+		if reflect.DeepEqual(dedupedParts[i].Attribs, memPart.Attribs) {
+			memPart.SPDFileName = dedupedParts[i].SPDFileName
+			return true
+		}
+	}
+
+	return false
+}
+
+func generateSPD(memPart *memPart, SPDId int, SPDDirName string) {
+	s := createSPD(&memPart.Attribs)
+	memPart.SPDFileName = fmt.Sprintf("ddr4-spd-%d.hex", SPDId)
+	ioutil.WriteFile(filepath.Join(SPDDirName, memPart.SPDFileName), []byte(s), 0644)
+}
+
+func readMemoryParts(memParts *memParts, memPartsFileName string) error {
+	databytes, err := ioutil.ReadFile(memPartsFileName)
+	if err != nil {
+		return err
+	}
+
+	return json.Unmarshal(databytes, memParts)
+}
+
+func validateSpeedMTps(speedBin int) error {
+	if _, ok := speedBinToSPDEncoding[speedBin]; ok == false {
+		return fmt.Errorf("Incorrect speed bin: DDR4-", speedBin)
+	}
+	return nil
+}
+
+func validateCapacityPerDie(capacityPerDieGb int) error {
+	if _, ok := densityGbToSPDEncoding[capacityPerDieGb]; ok == false {
+		return fmt.Errorf("Incorrect capacity per die: ", capacityPerDieGb)
+	}
+	return nil
+}
+
+func validateDiesPerPackage(dieCount int) error {
+	if dieCount >= 1 && dieCount <= 2 {
+		return nil
+	}
+	return fmt.Errorf("Incorrect dies per package count: ", dieCount)
+}
+
+func validateDeviceBusWidth(width int) error {
+	if width != 8 && width != 16 {
+		return fmt.Errorf("Incorrect device bus width: ", width)
+	}
+	return nil
+}
+
+func validateRanksPerPackage(ranks int) error {
+	if ranks >= 1 && ranks <= 2 {
+		return nil
+	}
+	return fmt.Errorf("Incorrect package ranks: ", ranks)
+}
+
+
+func validateCASLatency(CL int) error {
+	if CL >= 10 && CL <= 24 && CL != 23 {
+		return nil
+	}
+	return fmt.Errorf("Incorrect CAS latency: ", CL)
+}
+
+/*
+1) validate memory parts
+2) remove any fields that Intel does not care about
+*/
+
+/* verify the supplied CAS Latencies supported does not match default */
+func verifySupportedCASLatencies(part *memPart) error {
+	if part.Attribs.CASLatencies == getDefaultCASLatencies(&part.Attribs) {
+		return fmt.Errorf("CASLatencies for %s already matches default,\nPlease remove CASLatencies override line from the %s part attributes in the global part list and regenerate SPD Manifest", part.Name, part.Name)
+	}
+
+	return nil
+}
+
+func validateMemoryParts(memParts *memParts) error {
+	for i := 0; i < len(memParts.MemParts); i++ {
+		if err := validateSpeedMTps(memParts.MemParts[i].Attribs.SpeedMTps); err != nil {
+			return err
+		}
+		if err := validateCapacityPerDie(memParts.MemParts[i].Attribs.CapacityPerDieGb); err != nil {
+			return err
+		}
+		if err := validateDiesPerPackage(memParts.MemParts[i].Attribs.DiesPerPackage); err != nil {
+			return err
+		}
+		if err := validateDeviceBusWidth(memParts.MemParts[i].Attribs.DeviceBusWidth); err != nil {
+			return err
+		}
+		if err := validateRanksPerPackage(memParts.MemParts[i].Attribs.RanksPerPackage); err != nil {
+			return err
+		}
+		if err := validateCASLatency(memParts.MemParts[i].Attribs.CL_nRCD_nRP); err != nil {
+			return err
+		}
+		/* If CAS Latency was supplied, make sure it doesn't match default value */
+		if len(memParts.MemParts[i].Attribs.CASLatencies) != 0 {
+			if err := verifySupportedCASLatencies(&memParts.MemParts[i]); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+const (
+        /* First Byte */
+        CAS9 = 1 << 2
+        CAS10 = 1 << 3
+        CAS11 = 1 << 4
+        CAS12 = 1 << 5
+        CAS13 = 1 << 6
+        CAS14 = 1 << 7
+        /* Second Byte */
+        CAS15 = 1 << 0
+        CAS16 = 1 << 1
+        CAS17 = 1 << 2
+        CAS18 = 1 << 3
+        CAS19 = 1 << 4
+        CAS20 = 1 << 5
+        CAS21 = 1 << 6
+        CAS22 = 1 << 7
+        /* Third Byte */
+        CAS24 = 1 << 1
+)
+
+func encodeLatencies(latency int, memAttribs *memAttributes) error {
+	switch latency {
+	case 9:
+		memAttribs.CASFirstByte |= CAS9
+	case 10:
+		memAttribs.CASFirstByte |= CAS10
+	case 11:
+		memAttribs.CASFirstByte |= CAS11
+	case 12:
+		memAttribs.CASFirstByte |= CAS12
+	case 13:
+		memAttribs.CASFirstByte |= CAS13
+	case 14:
+		memAttribs.CASFirstByte |= CAS14
+	case 15:
+		memAttribs.CASSecondByte |= CAS15
+	case 16:
+		memAttribs.CASSecondByte |= CAS16
+	case 17:
+		memAttribs.CASSecondByte |= CAS17
+	case 18:
+		memAttribs.CASSecondByte |= CAS18
+	case 19:
+		memAttribs.CASSecondByte |= CAS19
+	case 20:
+		memAttribs.CASSecondByte |= CAS20
+	case 21:
+		memAttribs.CASSecondByte |= CAS21
+	case 22:
+		memAttribs.CASSecondByte |= CAS22
+	case 24:
+		memAttribs.CASThirdByte |= CAS24
+	default:
+		fmt.Errorf("Incorrect CAS Latency: ", latency)
+	}
+
+	return nil
+}
+
+/* Default CAS Latencies from Speed Bin tables in JEDS79-4C */
+func getDefaultCASLatencies(memAttribs *memAttributes) string {
+	var str string
+
+	switch memAttribs.SpeedMTps {
+	case 1600:
+		switch memAttribs.CL_nRCD_nRP {
+		case 10:
+			str = "9 10 11 12"
+		case 11:
+			str = "9 11 12"
+		case 12:
+			str = "10 12"
+		}
+	case 1866:
+		switch memAttribs.CL_nRCD_nRP {
+		case 12:
+			str = "9 10 12 13 14"
+		case 13:
+			str = "9 11 12 13 14"
+		case 14:
+			str = "10 12 14"
+		}
+	case 2133:
+		switch memAttribs.CL_nRCD_nRP {
+		case 14:
+			str = "9 10 12 14 15 16"
+		case 15:
+			str = "9 11 12 13 14 15 16"
+		case 16:
+			str = "10 12 14 16"
+		}
+	case 2400:
+		switch memAttribs.CL_nRCD_nRP {
+		case 15:
+			str = "9 10 12 14 15 16 17 18"
+		case 16:
+			str = "9 11 12 13 14 15 16 17 18"
+		case 17:
+			str = "10 11 12 13 14 15 16 17 18"
+		case 18:
+			str = "10 12 14 16 18"
+		}
+	case 2666:
+		switch memAttribs.CL_nRCD_nRP {
+		case 17:
+			str = "9 10 11 12 13 14 15 16 17 18 19 20"
+		case 18:
+			str = "9 10 11 12 13 14 15 16 17 18 19 20"
+		case 19:
+			str = "10 11 12 13 14 15 16 17 18 19 20"
+		case 20:
+			str = "10 12 14 16 18 20"
+		}
+	case 2933:
+		switch memAttribs.CL_nRCD_nRP {
+		case 19:
+			str = "9 10 11 12 13 14 15 16 17 18 19 20 21 22"
+		case 20:
+			str = "10 11 12 13 14 15 16 17 18 19 20 21 22"
+		case 21:
+			str = "10 11 12 13 14 15 16 17 18 19 20 21 22"
+		case 22:
+			str = "10 12 14 16 18 20 22"
+		}
+	case 3200:
+		switch memAttribs.CL_nRCD_nRP {
+		case 20:
+			str = "9 10 11 12 13 14 15 16 17 18 19 20 21 22 24"
+		case 22:
+			str = "10 11 12 13 14 15 16 17 18 19 20 21 22 24"
+		case 24:
+			str = "10 12 14 16 18 20 22 24"
+		}
+	}
+
+	return str
+}
+
+func updateCAS(memAttribs *memAttributes) error {
+	if len(memAttribs.CASLatencies) == 0 {
+		memAttribs.CASLatencies = getDefaultCASLatencies(memAttribs)
+	}
+
+	latencies := strings.Fields(memAttribs.CASLatencies)
+	for i := 0; i < len(latencies); i++ {
+		latency,err := strconv.Atoi(latencies[i])
+		if err != nil {
+			return fmt.Errorf("Unable to convert latency ", latencies[i])
+		}
+		if err := encodeLatencies(latency, memAttribs); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func getTAAMinPs(memAttribs *memAttributes) int {
+	return (memAttribs.CL_nRCD_nRP * 2000000) / memAttribs.SpeedMTps
+}
+
+func updateTAAMin(memAttribs *memAttributes) {
+	if memAttribs.TAAMinPs == 0 {
+		memAttribs.TAAMinPs = getTAAMinPs(memAttribs)
+	}
+}
+
+func updateTRCDMin(memAttribs *memAttributes) {
+	/* tRCDmin is same as tAAmin for all cases */
+	if memAttribs.TRCDMinPs == 0 {
+		memAttribs.TRCDMinPs = getTAAMinPs(memAttribs)
+	}
+}
+
+func updateTRPMin(memAttribs *memAttributes) {
+	/* tRPmin is same as tAAmin for all cases */
+	if memAttribs.TRPMinPs == 0 {
+		memAttribs.TRPMinPs = getTAAMinPs(memAttribs)
+	}
+}
+
+func updateTRASMin(memAttribs *memAttributes) {
+	if memAttribs.TRASMinPs == 0 {
+		memAttribs.TRASMinPs = speedBinToSPDEncoding[memAttribs.SpeedMTps].TRASMinPs
+	}
+}
+
+
+func updateTRCMin(memAttribs *memAttributes) {
+	if memAttribs.TRCMinPs == 0 {
+		memAttribs.TRCMinPs = getTRCMinPs(memAttribs)
+	}
+}
+
+func updateTCK(memAttribs *memAttributes) {
+	if memAttribs.TCKMinPs == 0 {
+		memAttribs.TCKMinPs = getDefaultTCKMinPs(memAttribs)
+	}
+	if memAttribs.TCKMaxPs == 0 {
+		memAttribs.TCKMaxPs = speedBinToSPDEncoding[memAttribs.SpeedMTps].TCKMaxPs
+	}
+}
+
+func updateTWRMin(memAttribs *memAttributes) {
+	if memAttribs.TWRMinPs == 0 {
+		memAttribs.TWRMinPs = TimingValueTWRMinPs
+	}
+}
+
+func  updateTWTRMin(memAttribs *memAttributes) {
+	if memAttribs.TWTRLMinPs == 0 {
+		memAttribs.TWTRLMinPs = TimingValueTWTRLMinPs
+	}
+	if memAttribs.TWTRSMinPs == 0 {
+		memAttribs.TWTRSMinPs = TimingValueTWTRSMinPs
+	}
+}
+
+func updateMemoryAttributes(memAttribs *memAttributes) {
+	updateTCK(memAttribs)
+	updateTAAMin(memAttribs)
+	updateTRCDMin(memAttribs)
+	updateTRPMin(memAttribs)
+	updateTRASMin(memAttribs)
+	updateTRCMin(memAttribs)
+	updateTWRMin(memAttribs)
+	updateTWTRMin(memAttribs)
+	updateCAS(memAttribs)
+	updateTRFC1Min(memAttribs)
+	updateTRFC2Min(memAttribs)
+	updateTRFC4Min(memAttribs)
+	updateTCCDLMin(memAttribs)
+	updateTRRDSMin(memAttribs)
+	updateTRRDLMin(memAttribs)
+	updateTFAWMin(memAttribs)
+}
+
+func isPlatformSupported(platform string) error {
+	var ok bool
+
+	currPlatform, ok = platformMap[platform]
+	if ok == false {
+		return fmt.Errorf("Unsupported platform: ", platform)
+	}
+
+	return nil
+}
+
+func usage() {
+	fmt.Printf("\nUsage: %s <spd_dir> <mem_parts_list_json> <platform>\n\n", os.Args[0])
+	fmt.Printf("   where,\n")
+	fmt.Printf("   spd_dir = Directory path containing SPD files and manifest generated by gen_spd.go\n")
+	fmt.Printf("   mem_parts_list_json = JSON File containing list of memory parts and attributes\n")
+	fmt.Printf("   platform = SoC Platform for which the SPDs are being generated\n\n\n")
+}
+
+func main() {
+	if len(os.Args) != 4 {
+		usage()
+		log.Fatal("Incorrect number of arguments")
+	}
+
+	var memParts memParts
+	var dedupedParts []*memPart
+
+	SPDDir, GlobalMemPartsFile, Platform := os.Args[1], os.Args[2], strings.ToUpper(os.Args[3])
+
+	if err := isPlatformSupported(Platform); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := readMemoryParts(&memParts, GlobalMemPartsFile); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := validateMemoryParts(&memParts); err != nil {
+		log.Fatal(err)
+	}
+
+	SPDId := 1
+
+	for i := 0; i < len(memParts.MemParts); i++ {
+		updateMemoryAttributes(&memParts.MemParts[i].Attribs)
+		if dedupeMemoryPart(dedupedParts, &memParts.MemParts[i]) == false {
+			generateSPD(&memParts.MemParts[i], SPDId, SPDDir)
+			SPDId++
+			dedupedParts = append(dedupedParts, &memParts.MemParts[i])
+		}
+	}
+
+	if err := writeSPDManifest(&memParts, SPDDir); err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/util/spd_tools/intel/ddr4/global_ddr4_mem_parts.json.txt b/util/spd_tools/intel/ddr4/global_ddr4_mem_parts.json.txt
new file mode 100644
index 0000000000..4e9c7c8e95
--- /dev/null
+++ b/util/spd_tools/intel/ddr4/global_ddr4_mem_parts.json.txt
@@ -0,0 +1,37 @@
+{
+    "parts": [
+        {
+            "name": "H5AN8G6NDJR-XNC",
+            "attribs": {
+                "speedMTps": 3200,
+                "CL_nRCD_nRP": 22,
+                "capacityPerDieGb": 8,
+                "diesPerPackage": 1,
+                "deviceBusWidth": 16,
+                "ranksPerPackage": 1
+            }
+        },
+        {
+            "name": "MT40A512M16TB-062E:J",
+            "attribs": {
+                "speedMTps": 3200,
+                "CL_nRCD_nRP": 22,
+                "capacityPerDieGb": 8,
+                "diesPerPackage": 1,
+                "deviceBusWidth": 16,
+                "ranksPerPackage": 1
+            }
+        },
+        {
+            "name": "H5ANAG6NCMR-XNC",
+            "attribs": {
+                "speedMTps": 3200,
+                "CL_nRCD_nRP": 22,
+                "capacityPerDieGb": 8,
+                "diesPerPackage": 2,
+                "deviceBusWidth": 16,
+                "ranksPerPackage": 1
+            }
+        }
+    ]
+}