util/spd_tools: Add support for exclusive IDs

Currently memory parts that use the same SPD are assigned the same ID by
spd_tools. This commit adds support for exclusive IDs. When given an
exclusive ID a memory part will not share its ID with other parts unless
they also have the same exclusive ID.

BUG=b:225161910
TEST=Ran part_id_gen and checked that exclusive IDs work correctly and
that the current behavior still works in their abscence.

Signed-off-by: Robert Zieba <robertzieba@google.com>
Change-Id: Ife5afe32337f69bc06451ce16238c7a83bc983c8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62905
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

util/spd_tools/README.md

@@ -459,10 +459,14 @@ This program takes the following inputs:
 *   The memory technology used by the board, e.g. lp4x.
 *   The path to the directory where the generated Makefile.inc should be placed.
 *   A CSV file containing a list of the memory parts used by the board, with an
-    optional fixed ID for each part. NOTE: Only assign a fixed ID if required
+*   optional fixed or exclusive ID for each part. A fixed ID is simply an integer
-    for legacy reasons.
+*   and it ensure that part (and any that share the same SPD) will be assigned
+*   that ID. An exclusive ID is prefixed with `*` and ensures that only parts with
+*   the same exclusive ID will be assigned that ID, even if they would otherwise
+*   share the same ID.
+*   NOTE: Only assign a fixed/exclusive ID if required for legacy reasons.
 
-Example of a CSV file using fixed IDs:
+Example of a CSV file using fixed and exclusive IDs:
 
 ```
 K4AAG165WA-BCWE,1
@@ -470,13 +474,15 @@ MT40A512M16TB-062E:J
 MT40A1G16KD-062E:E
 K4A8G165WC-BCWE
 H5AN8G6NDJR-XNC,8
-H5ANAG6NCMR-XNC
+H5ANAG6NCMR-XNC,*9
 ```
 
 Explanation: This will ensure that the SPDs for K4AAG165WA-BCWE and
-H5AN8G6NDJR-XNC are assigned to IDs 1 and 8 respectively. The SPDs for all other
+H5AN8G6NDJR-XNC are assigned to IDs 1 and 8 respectively. H5ANAG6NCMR-XNC
-memory parts will be assigned to the first compatible ID. Assigning fixed IDs
+will be assigned ID 9 and no other part will be assigned ID 9 even if it
-may result in duplicate SPD entries or gaps in the ID mapping.
+shares the same SPD. The SPDs for all other memory parts will be assigned to
+the first compatible ID. Assigning fixed/exclusive IDs may result in duplicate
+SPD entries or gaps in the ID mapping.
 
 ### Output
 

util/spd_tools/src/part_id_gen/part_id_gen.go

@@ -93,9 +93,18 @@ func checkArgs(platform string, memTech string, makefileDir string, memPartsUsed
 	return nil
 }
 
+type mappingType int
+
+const (
+	Auto mappingType = iota
+	Fixed
+	Exclusive
+)
+
 type usedPart struct {
 	partName string
 	index    int
+	mapping  mappingType
 }
 
 func readPlatformsManifest(memTech string) (map[string]string, error) {
@@ -174,16 +183,28 @@ func readParts(memPartsUsedFileName string) ([]usedPart, error) {
 		}
 
 		if len(fields) == 1 {
-			parts = append(parts, usedPart{fields[0], -1})
+			parts = append(parts, usedPart{fields[0], -1, Auto})
 		} else if len(fields) == 2 {
-			assignedId, err := strconv.Atoi(fields[1])
+			var mapping = Auto
+			var assignedId = -1
+			var err error = nil
+
+			if len(fields[1]) >= 2 && fields[1][0] == '*' {
+				// Exclusive mapping
+				mapping = Exclusive
+				assignedId, err = strconv.Atoi(fields[1][1:])
+			} else {
+				mapping = Fixed
+				assignedId, err = strconv.Atoi(fields[1])
+			}
+
 			if err != nil {
 				return nil, err
 			}
 			if assignedId > MaxMemoryId || assignedId < 0 {
 				return nil, fmt.Errorf("Out of bounds assigned id %d for part %s", assignedId, fields[0])
 			}
-			parts = append(parts, usedPart{fields[0], assignedId})
+			parts = append(parts, usedPart{fields[0], assignedId, mapping})
 		} else {
 			return nil, fmt.Errorf("mem_parts_used_file file is incorrectly formatted")
 		}
@@ -245,7 +266,7 @@ type partIds struct {
 }
 
 func getFileHeader() string {
-    return `# SPDX-License-Identifier: GPL-2.0-or-later
+	return `# SPDX-License-Identifier: GPL-2.0-or-later
 # This is an auto-generated file. Do not edit!!
 # Generated by:
 ` + fmt.Sprintf("# %s\n\n", strings.Join(os.Args[0:], " "))
@@ -262,6 +283,7 @@ func getFileHeader() string {
  */
 func genPartIdInfo(parts []usedPart, partToSPDMap map[string]string, SPDToIndexMap map[string]int, makefileDirName string) ([]partIds, error) {
 	partIdList := []partIds{}
+	assignedMapping := []mappingType{}
 	var s string
 
 	// Assign parts with fixed ids first
@@ -280,19 +302,34 @@ func genPartIdInfo(parts []usedPart, partToSPDMap map[string]string, SPDToIndexM
 			return nil, fmt.Errorf("Failed to find part ", p.partName, " in SPD Manifest. Please add the part to global part list and regenerate SPD Manifest")
 		}
 
-		// Extend partIdList with empty entries if needed
+		// Extend partIdList and assignedMapping with empty entries if needed
 		for i := len(partIdList) - 1; i < p.index; i++ {
 			partIdList = append(partIdList, partIds{})
+			assignedMapping = append(assignedMapping, Auto)
 		}
 
-		if partIdList[p.index].SPDFileName != "" {
+		// Only allow parts with the same index if they share the same SPD
-			return nil, fmt.Errorf("Part ", p.partName, " is assigned to an already assigned ID ", p.index)
+		assignedSPD := partIdList[p.index].SPDFileName
+		if assignedSPD != "" && assignedSPD != partToSPDMap[p.partName] {
+			return nil, fmt.Errorf("ID %d is already assigned to %s, conflicting with %s(%s)", p.index, assignedSPD, p.partName, SPDFileName)
 		}
 
-		partIdList[p.index] = partIds{SPDFileName: SPDFileName, memParts: p.partName}
+		mapping := assignedMapping[p.index]
+		if (mapping == Fixed && p.mapping == Exclusive) || (mapping == Exclusive && p.mapping == Fixed) {
+			return nil, fmt.Errorf("Exclusive/non-exclusive conflict in assigning %s to ID %d", p.partName, p.index)
+		} else {
+			assignedMapping[p.index] = p.mapping
+		}
+
+		if partIdList[p.index].memParts == "" {
+			partIdList[p.index] = partIds{SPDFileName: SPDFileName, memParts: p.partName}
+		} else {
+			partIdList[p.index].memParts += ", " + p.partName
+		}
 
 		// SPDToIndexMap should point to first assigned index in the used part list
-		if SPDToIndexMap[SPDFileName] < 0 {
+		// Exclusive entries don't update the map because they're not valid for auto assigning
+		if SPDToIndexMap[SPDFileName] < 0 && p.mapping != Exclusive {
 			SPDToIndexMap[SPDFileName] = p.index
 		}
 	}
@@ -317,7 +354,8 @@ func genPartIdInfo(parts []usedPart, partToSPDMap map[string]string, SPDToIndexM
 		}
 
 		index := SPDToIndexMap[SPDFileName]
-		if index != -1 {
+		// Only Exclusive mappings don't allow automatic assigning of parts
+		if index != -1 && assignedMapping[index] != Exclusive {
 			partIdList[index].memParts += ", " + p.partName
 			appendPartIdInfo(&s, p.partName, index)
 			continue
@@ -338,6 +376,7 @@ func genPartIdInfo(parts []usedPart, partToSPDMap map[string]string, SPDToIndexM
 				return nil, fmt.Errorf("Maximum part ID %d exceeded.", MaxMemoryId)
 			}
 			partIdList = append(partIdList, partIds{})
+			assignedMapping = append(assignedMapping, Auto)
 		}
 
 		SPDToIndexMap[SPDFileName] = index