platform/x86: dell-smbios: Add helper for checking supported class

Add helper that returns true if smbios command class is supported.
Signed-off-by: Lyndon Sanche <lsanche@lyndeno.ca>
Link: https://lore.kernel.org/r/20240529174843.13226-2-lsanche@lyndeno.caReviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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

@@ -350,6 +350,15 @@ void dell_laptop_call_notifier(unsigned long action, void *data)
 }
 EXPORT_SYMBOL_GPL(dell_laptop_call_notifier);
 
+bool dell_smbios_class_is_supported(u16 class)
+{
+	/* Classes over 30 always unsupported */
+	if (class > 30)
+		return false;
+	return da_supported_commands & (1 << class);
+}
+EXPORT_SYMBOL_GPL(dell_smbios_class_is_supported);
+
 static void __init parse_da_table(const struct dmi_header *dm)
 {
 	/* Final token is a terminator, so we don't want to copy it */

drivers/platform/x86/dell/dell-smbios.h

@@ -73,6 +73,7 @@ enum dell_laptop_notifier_actions {
 int dell_laptop_register_notifier(struct notifier_block *nb);
 int dell_laptop_unregister_notifier(struct notifier_block *nb);
 void dell_laptop_call_notifier(unsigned long action, void *data);
+bool dell_smbios_class_is_supported(u16 class);
 
 /* for the supported backends */
 #ifdef CONFIG_DELL_SMBIOS_WMI