dm: i2c: Add an I2C EEPROM simulator

To enable testing of I2C, add a simple I2C EEPROM simulator for sandbox.
It supports reading and writing from a small data store.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

arch/sandbox/include/asm/test.h

@@ -0,0 +1,26 @@
+/*
+ * Test-related constants for sandbox
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __ASM_TEST_H
+#define __ASM_TEST_H
+
+/* The sandbox driver always permits an I2C device with this address */
+#define SANDBOX_I2C_TEST_ADDR	0x59
+
+enum sandbox_i2c_eeprom_test_mode {
+	SIE_TEST_MODE_NONE,
+	/* Permits read/write of only one byte per I2C transaction */
+	SIE_TEST_MODE_SINGLE_BYTE,
+};
+
+void sandbox_i2c_eeprom_set_test_mode(struct udevice *dev,
+				      enum sandbox_i2c_eeprom_test_mode mode);
+
+void sandbox_i2c_eeprom_set_offset_len(struct udevice *dev, int offset_len);
+
+#endif