platform/x86: dell-smbios-base: Support systems without tokens

Some Dell servers can use dell-smbios but they don't support the
token interface.  Make it optional.
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/dell-smbios-base.c

@@ -212,6 +212,12 @@ int dell_smbios_call_filter(struct device *d,
 	if ((buffer->cmd_class == CLASS_TOKEN_READ ||
 	     buffer->cmd_class == CLASS_TOKEN_WRITE) &&
 	     buffer->cmd_select < 3) {
+		/* tokens enabled ? */
+		if (!da_tokens) {
+			dev_dbg(d, "no token support on this system\n");
+			return -EINVAL;
+		}
+
 		/* find the matching token ID */
 		for (i = 0; i < da_num_tokens; i++) {
 			if (da_tokens[i].location != buffer->input[0])
@@ -315,6 +321,9 @@ struct calling_interface_token *dell_smbios_find_token(int tokenid)
 {
 	int i;
 
+	if (!da_tokens)
+		return NULL;
+
 	for (i = 0; i < da_num_tokens; i++) {
 		if (da_tokens[i].tokenID == tokenid)
 			return &da_tokens[i];
@@ -565,11 +574,6 @@ static int __init dell_smbios_init(void)
 
 	dmi_walk(find_tokens, NULL);
 
-	if (!da_tokens)  {
-		pr_info("Unable to find dmi tokens\n");
-		return -ENODEV;
-	}
-
 	ret = platform_driver_register(&platform_driver);
 	if (ret)
 		goto fail_platform_driver;
@@ -583,13 +587,6 @@ static int __init dell_smbios_init(void)
 	if (ret)
 		goto fail_platform_device_add;
 
-	/* duplicate tokens will cause problems building sysfs files */
-	zero_duplicates(&platform_device->dev);
-
-	ret = build_tokens_sysfs(platform_device);
-	if (ret)
-		goto fail_create_group;
-
 	/* register backends */
 	wmi = init_dell_smbios_wmi();
 	if (wmi)
@@ -600,6 +597,15 @@ static int __init dell_smbios_init(void)
 	if (wmi && smm) {
 		pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
 			wmi, smm);
+		goto fail_create_group;
+	}
+
+	if (da_tokens)  {
+		/* duplicate tokens will cause problems building sysfs files */
+		zero_duplicates(&platform_device->dev);
+
+		ret = build_tokens_sysfs(platform_device);
+		if (ret)
 			goto fail_sysfs;
 	}
 
@@ -628,6 +634,7 @@ static void __exit dell_smbios_exit(void)
 	exit_dell_smbios_smm();
 	mutex_lock(&smbios_mutex);
 	if (platform_device) {
+		if (da_tokens)
 			free_group(platform_device);
 		platform_device_unregister(platform_device);
 		platform_driver_unregister(&platform_driver);