Change in coreboot[master]: util/spd_tools: Add support for exclusive IDs

[Karthik Ramasubramanian (Code Review)]

Karthik Ramasubramanian has submitted this change. ( https://review.coreboot.org/c/coreboot/+/62905 )

Change subject: util/spd_tools: Add support for exclusive IDs
......................................................................

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 
Change-Id: Ife5afe32337f69bc06451ce16238c7a83bc983c8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62905
Tested-by: build bot (Jenkins) 
Reviewed-by: Karthik Ramasubramanian 
---
M util/spd_tools/README.md
M util/spd_tools/src/part_id_gen/part_id_gen.go
2 files changed, 62 insertions(+), 17 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Karthik Ramasubramanian: Looks good to me, approved

diff --git a/util/spd_tools/README.md b/util/spd_tools/README.md
index 3a1342c..01bc417 100644
--- a/util/spd_tools/README.md
+++ b/util/spd_tools/README.md
@@ -459,10 +459,14 @@
 *   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
-    for legacy reasons.
+*   optional fixed or exclusive ID for each part. A fixed ID is simply an integer
+*   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 @@
 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
-memory parts will be assigned to the first compatible ID. Assigning fixed IDs
-may result in duplicate SPD entries or gaps in the ID mapping.
+H5AN8G6NDJR-XNC are assigned to IDs 1 and 8 respectively. H5ANAG6NCMR-XNC
+will be assigned ID 9 and no other part will be assigned ID 9 even if it
+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

diff --git a/util/spd_tools/src/part_id_gen/part_id_gen.go b/util/spd_tools/src/part_id_gen/part_id_gen.go
index 750b825..65e07f4 100644
--- a/util/spd_tools/src/part_id_gen/part_id_gen.go
+++ b/util/spd_tools/src/part_id_gen/part_id_gen.go
@@ -93,9 +93,18 @@
    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 @@
    	}

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 @@
 }

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 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 @@
    		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 != "" {
-			return nil, fmt.Errorf("Part ", p.partName, " is assigned to an already assigned ID ", p.index)
+		// Only allow parts with the same index if they share the same SPD
+		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 @@
    	}

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 @@
    			return nil, fmt.Errorf("Maximum part ID %d exceeded.", MaxMemoryId)
    		}
    		partIdList = append(partIdList, partIds{})
+			assignedMapping = append(assignedMapping, Auto)
    	}

SPDToIndexMap[SPDFileName] = index