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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Intel Keembay SOC Firmware API Layer
+ *
+ * Copyright (C) 2020, Intel Corporation
+ *
+ * Author: Muhammad Husaini Zulkifli <Muhammad.Husaini.Zulkifli@intel.com>
+ */
+
+#ifndef __FIRMWARE_KEEMBAY_SMC_H__
+#define __FIRMWARE_KEEMBAY_SMC_H__
+
+#include <linux/arm-smccc.h>
+
+/*
+ * This file defines an API function that can be called by a device driver in order to
+ * communicate with Trusted Firmware - A profile(TF-A) or Trusted Firmware - M profile (TF-M).
+ */
+
+#define KEEMBAY_SET_1V8_IO_RAIL 1
+#define KEEMBAY_SET_3V3_IO_RAIL 0
+
+#define IOV_1V8 1800000
+#define IOV_3V3 3300000
+
+#define ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_32, \
+ ARM_SMCCC_OWNER_SIP, \
+ 0xFF26)
+
+#if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)
+/*
+ * Voltage applied on the IO Rail is controlled from the Always On Register using specific
+ * bits in AON_CGF1 register. This is a secure register. Keem Bay SOC cannot exposed this
+ * register address to the outside world.
+ */
+static inline int keembay_io_rail_supplied_voltage(int volt)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE, volt, &res);
+ if ((int)res.a0 < 0)
+ return -EINVAL;
+
+ return 0;
+}
+#else
+static inline int keembay_io_rail_supplied_voltage(int volt)
+{
+ return -ENODEV;
+}
+#endif
+#endif /* __FIRMWARE_KEEMBAY_SMC_H__ */