diff --git a/test/dm/sf.c b/test/dm/sf.c
index 35241b9..b23e7f8 100644
--- a/test/dm/sf.c
+++ b/test/dm/sf.c
@@ -6,6 +6,8 @@
 #include <common.h>
 #include <dm.h>
 #include <fdtdec.h>
+#include <mapmem.h>
+#include <os.h>
 #include <spi.h>
 #include <spi_flash.h>
 #include <asm/state.h>
@@ -13,9 +15,49 @@
 #include <dm/util.h>
 #include <test/ut.h>
 
-/* Test that sandbox SPI flash works correctly */
+/* Simple test of sandbox SPI flash */
 static int dm_test_spi_flash(struct unit_test_state *uts)
 {
+	struct udevice *dev, *emul;
+	int full_size = 0x200000;
+	int size = 0x10000;
+	u8 *src, *dst;
+	int i;
+
+	src = map_sysmem(0x20000, full_size);
+	ut_assertok(os_write_file("spi.bin", src, full_size));
+	ut_assertok(uclass_first_device_err(UCLASS_SPI_FLASH, &dev));
+
+	dst = map_sysmem(0x20000 + full_size, full_size);
+	ut_assertok(spi_flash_read_dm(dev, 0, size, dst));
+	ut_assertok(memcmp(src, dst, size));
+
+	/* Erase */
+	ut_assertok(spi_flash_erase_dm(dev, 0, size));
+	ut_assertok(spi_flash_read_dm(dev, 0, size, dst));
+	for (i = 0; i < size; i++)
+		ut_asserteq(dst[i], 0xff);
+
+	/* Write some new data */
+	for (i = 0; i < size; i++)
+		src[i] = i;
+	ut_assertok(spi_flash_write_dm(dev, 0, size, src));
+	ut_assertok(spi_flash_read_dm(dev, 0, size, dst));
+	ut_assertok(memcmp(src, dst, size));
+
+	/*
+	 * Since we are about to destroy all devices, we must tell sandbox
+	 * to forget the emulation device
+	 */
+	sandbox_sf_unbind_emul(state_get_current(), 0, 0);
+
+	return 0;
+}
+DM_TEST(dm_test_spi_flash, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Functional test that sandbox SPI flash works correctly */
+static int dm_test_spi_flash_func(struct unit_test_state *uts)
+{
 	/*
 	 * Create an empty test file and run the SPI flash tests. This is a
 	 * long way from being a unit test, but it does test SPI device and
@@ -39,4 +81,4 @@
 
 	return 0;
 }
-DM_TEST(dm_test_spi_flash, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_spi_flash_func, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);