diff --git a/driver/ioexpander_pca9555.h b/driver/ioexpander_pca9555.h
new file mode 100644
index 0000000000..3a932ceef0
--- /dev/null
+++ b/driver/ioexpander_pca9555.h
@@ -0,0 +1,41 @@
+/* Copyright 2017 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * NXP PCA9555 I/O Port expander driver header
+ */
+
+#ifndef __CROS_EC_IOEXPANDER_PCA9555_H
+#define __CROS_EC_IOEXPANDER_PCA9555_H
+
+#include "i2c.h"
+
+#define PCA9555_CMD_INPUT_PORT_0		0
+#define PCA9555_CMD_INPUT_PORT_1		1
+#define PCA9555_CMD_OUTPUT_PORT_0		2
+#define PCA9555_CMD_OUTPUT_PORT_1		3
+#define PCA9555_CMD_POLARITY_INVERSION_PORT_0	4
+#define PCA9555_CMD_POLARITY_INVERSION_PORT_1	5
+#define PCA9555_CMD_CONFIGURATION_PORT_0	6
+#define PCA9555_CMD_CONFIGURATION_PORT_1	7
+
+#define PCA9555_IO_0	(1 << 0)
+#define PCA9555_IO_1	(1 << 1)
+#define PCA9555_IO_2	(1 << 2)
+#define PCA9555_IO_3	(1 << 3)
+#define PCA9555_IO_4	(1 << 4)
+#define PCA9555_IO_5	(1 << 5)
+#define PCA9555_IO_6	(1 << 6)
+#define PCA9555_IO_7	(1 << 7)
+
+static inline int pca9555_read(int port, int addr, int reg, int *data_ptr)
+{
+	return i2c_read8(port, addr, reg, data_ptr);
+}
+
+static inline int pca9555_write(int port, int addr, int reg, int data)
+{
+	return i2c_write8(port, addr, reg, data);
+}
+
+#endif /* __CROS_EC_IOEXPANDER_PCA9555_H */