v4.19.13 snapshot.
diff --git a/drivers/acpi/debugfs.c b/drivers/acpi/debugfs.c
new file mode 100644
index 0000000..68bb305
--- /dev/null
+++ b/drivers/acpi/debugfs.c
@@ -0,0 +1,21 @@
+/*
+ * debugfs.c - ACPI debugfs interface to userspace.
+ */
+
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/debugfs.h>
+#include <linux/acpi.h>
+
+#include "internal.h"
+
+#define _COMPONENT ACPI_SYSTEM_COMPONENT
+ACPI_MODULE_NAME("debugfs");
+
+struct dentry *acpi_debugfs_dir;
+EXPORT_SYMBOL_GPL(acpi_debugfs_dir);
+
+void __init acpi_debugfs_init(void)
+{
+ acpi_debugfs_dir = debugfs_create_dir("acpi", NULL);
+}