[settings] Eliminate settings "tag magic"

Create an explicit concept of "settings scope" and eliminate the magic
values used for numerical setting tags.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 11 insertions, 21 deletions

diff --git a/src/interface/smbios/smbios_settings.c b/src/interface/smbios/smbios_settings.c
index 663da968..7b2efcd7 100644
--- a/src/interface/smbios/smbios_settings.c
+++ b/src/interface/smbios/smbios_settings.c
@@ -27,15 +27,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/uuid.h>
 #include <ipxe/smbios.h>
 
-/** SMBIOS settings tag magic number */
-#define SMBIOS_TAG_MAGIC 0x5B /* "SmBios" */
-
-/**
- * Construct SMBIOS empty tag
- *
- * @ret tag		SMBIOS setting tag
- */
-#define SMBIOS_EMPTY_TAG ( SMBIOS_TAG_MAGIC << 24 )
+/** SMBIOS settings scope */
+static struct settings_scope smbios_settings_scope;
 
 /**
  * Construct SMBIOS raw-data tag
@@ -46,8 +39,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
  * @ret tag		SMBIOS setting tag
  */
 #define SMBIOS_RAW_TAG( _type, _structure, _field )		\
-	( ( SMBIOS_TAG_MAGIC << 24 ) |				\
-	  ( (_type) << 16 ) |					\
+	( ( (_type) << 16 ) |					\
 	  ( offsetof ( _structure, _field ) << 8 ) |		\
 	  ( sizeof ( ( ( _structure * ) 0 )->_field ) ) )
 
@@ -60,8 +52,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
  * @ret tag		SMBIOS setting tag
  */
 #define SMBIOS_STRING_TAG( _type, _structure, _field )		\
-	( ( SMBIOS_TAG_MAGIC << 24 ) |				\
-	  ( (_type) << 16 ) |					\
+	( ( (_type) << 16 ) |					\
 	  ( offsetof ( _structure, _field ) << 8 ) )
 
 /**
@@ -73,11 +64,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
  */
 static int smbios_applies ( struct settings *settings __unused,
 			    struct setting *setting ) {
-	unsigned int tag_magic;
 
-	/* Check tag magic */
-	tag_magic = ( setting->tag >> 24 );
-	return ( tag_magic == SMBIOS_TAG_MAGIC );
+	return ( setting->scope == &smbios_settings_scope );
 }
 
 /**
@@ -93,18 +81,15 @@ static int smbios_fetch ( struct settings *settings __unused,
 			  struct setting *setting,
 			  void *data, size_t len ) {
 	struct smbios_structure structure;
-	unsigned int tag_magic;
 	unsigned int tag_type;
 	unsigned int tag_offset;
 	unsigned int tag_len;
 	int rc;
 
 	/* Split tag into type, offset and length */
-	tag_magic = ( setting->tag >> 24 );
 	tag_type = ( ( setting->tag >> 16 ) & 0xff );
 	tag_offset = ( ( setting->tag >> 8 ) & 0xff );
 	tag_len = ( setting->tag & 0xff );
-	assert ( tag_magic == SMBIOS_TAG_MAGIC );
 
 	/* Find SMBIOS structure */
 	if ( ( rc = find_smbios_structure ( tag_type, &structure ) ) != 0 )
@@ -170,10 +155,10 @@ static struct settings_operations smbios_settings_operations = {
 /** SMBIOS settings */
 static struct settings smbios_settings = {
 	.refcnt = NULL,
-	.tag_magic = SMBIOS_EMPTY_TAG,
 	.siblings = LIST_HEAD_INIT ( smbios_settings.siblings ),
 	.children = LIST_HEAD_INIT ( smbios_settings.children ),
 	.op = &smbios_settings_operations,
+	.default_scope = &smbios_settings_scope,
 };
 
 /** Initialise SMBIOS settings */
@@ -200,6 +185,7 @@ struct setting uuid_setting __setting ( SETTING_HOST ) = {
 	.tag = SMBIOS_RAW_TAG ( SMBIOS_TYPE_SYSTEM_INFORMATION,
 				struct smbios_system_information, uuid ),
 	.type = &setting_type_uuid,
+	.scope = &smbios_settings_scope,
 };
 
 /** Other SMBIOS named settings */
@@ -211,6 +197,7 @@ struct setting smbios_named_settings[] __setting ( SETTING_HOST_EXTRA ) = {
 					   struct smbios_system_information,
 					   manufacturer ),
 		.type = &setting_type_string,
+		.scope = &smbios_settings_scope,
 	},
 	{
 		.name = "product",
@@ -219,6 +206,7 @@ struct setting smbios_named_settings[] __setting ( SETTING_HOST_EXTRA ) = {
 					   struct smbios_system_information,
 					   product ),
 		.type = &setting_type_string,
+		.scope = &smbios_settings_scope,
 	},
 	{
 		.name = "serial",
@@ -227,6 +215,7 @@ struct setting smbios_named_settings[] __setting ( SETTING_HOST_EXTRA ) = {
 					   struct smbios_system_information,
 					   serial ),
 		.type = &setting_type_string,
+		.scope = &smbios_settings_scope,
 	},
 	{
 		.name = "asset",
@@ -235,5 +224,6 @@ struct setting smbios_named_settings[] __setting ( SETTING_HOST_EXTRA ) = {
 					   struct smbios_enclosure_information,
 					   asset_tag ),
 		.type = &setting_type_string,
+		.scope = &smbios_settings_scope,
 	},
 };