1 files changed, 23 insertions, 0 deletions
diff --git a/src/arch/x86/include/smm_call.h b/src/arch/x86/include/smm_call.h
new file mode 100644
index 0000000000..c0d96c0182
--- /dev/null
+++ b/src/arch/x86/include/smm_call.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <stdint.h>
+#include <cpu/x86/smm.h>
+
+/*
+ * calls into SMM with the given cmd and subcmd in eax, and arg in ebx
+ *
+ * static inline because the resulting assembly is often smaller than
+ * the call sequence due to constant folding.
+ */
+static inline u32 call_smm(u8 cmd, u8 subcmd, void *arg)
+{
+	u32 res = 0;
+	__asm__ __volatile__ (
+		"outb %%al, %%dx"
+		: "=a" (res)
+		: "a" ((subcmd << 8) | cmd),
+		  "b" (arg),
+		  "d" (APM_CNT)
+		: "memory");
+	return res;
+}