tools/intel_vbt_decode: Decode block 3 (Display Toggle Option)

Decode VBT block 3 (Display Toggle Option).

On ALM the block appears to contain some kind of actual toggle
list of child devices, on all more modern machines it just has
the feature bits.

Example output from ALM:
BDB block 3 (27 bytes, min 3 bytes) - Display toggle option block:
        0000: 03 1b 00 00 0c 00 08 00  01 00 09 00 02 00 00 00
        0010: 00 00 00 00 00 00 00 00  00 00 00 00 00 00

        Feature bits: 0x00
        Num entries: 12
        Toggle list #1: LFP1 (0x0008)
        Toggle list #2: CRT (0x0001)
        Toggle list #3: CRT,LFP1 (0x0009)
        Toggle list #4: TV (0x0002)
        Toggle list #5: none (0x0000)
        Toggle list #6: none (0x0000)
        Toggle list #7: none (0x0000)
        Toggle list #8: none (0x0000)
        Toggle list #9: none (0x0000)
        Toggle list #10: none (0x0000)
        Toggle list #11: none (0x0000)
        Toggle list #12: none (0x0000)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>

tools/intel_vbt_decode.c

@@ -316,6 +316,8 @@ static size_t block_min_size(const struct context *context, int section_id)
 		return sizeof(struct bdb_general_features);
 	case BDB_GENERAL_DEFINITIONS:
 		return sizeof(struct bdb_general_definitions);
+	case BDB_DISPLAY_TOGGLE:
+		return sizeof(struct bdb_display_toggle);
 	case BDB_PSR:
 		return sizeof(struct bdb_psr);
 	case BDB_CHILD_DEVICE_TABLE:
@@ -1249,6 +1251,20 @@ static void dump_general_definitions(struct context *context,
 			   child_dev_num, defs->child_dev_size);
 }
 
+static void dump_display_toggle(struct context *context,
+				const struct bdb_block *block)
+{
+	const struct bdb_display_toggle *t = block_data(block);
+
+	printf("\tFeature bits: 0x%02x\n", t->feature_bits);
+	printf("\tNum entries: %d\n", t->num_entries);
+
+	for (int i = 0; i < t->num_entries; i++)
+		printf("\tToggle list #%d: %s (0x%04x)\n",
+		       i+1, child_device_handle(context, t->list[i]),
+		       t->list[i]);
+}
+
 static void dump_legacy_child_devices(struct context *context,
 				      const struct bdb_block *block)
 {
@@ -2727,6 +2743,11 @@ struct dumper dumpers[] = {
 		.name = "General definitions block",
 		.dump = dump_general_definitions,
 	},
+	{
+		.id = BDB_DISPLAY_TOGGLE,
+		.name = "Display toggle option block",
+		.dump = dump_display_toggle,
+	},
 	{
 		.id = BDB_PSR,
 		.min_bdb_version = 165,