dm: sound: Create a uclass for i2s

The i2s bus is commonly used with audio codecs. It provides a way to
stream digital data sychronously in both directions. U-Boot only supports
audio output, so this uclass is very simple, with a single tx_data()
method.

Add a uclass and a test for i2s.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/Makefile b/test/dm/Makefile
index ef450b7..28ede9a 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -22,6 +22,7 @@
 obj-$(CONFIG_DM_GPIO) += gpio.o
 obj-$(CONFIG_DM_HWSPINLOCK) += hwspinlock.o
 obj-$(CONFIG_DM_I2C) += i2c.o
+obj-$(CONFIG_DM_SOUND) += i2s.o
 obj-$(CONFIG_LED) += led.o
 obj-$(CONFIG_DM_MAILBOX) += mailbox.o
 obj-$(CONFIG_DM_MMC) += mmc.o
diff --git a/test/dm/i2s.c b/test/dm/i2s.c
new file mode 100644
index 0000000..49ebc35
--- /dev/null
+++ b/test/dm/i2s.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <i2s.h>
+#include <dm/test.h>
+#include <test/ut.h>
+#include <asm/test.h>
+
+/* Basic test of the i2s codec uclass */
+static int dm_test_i2s(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	u8 data[3];
+
+	/* check probe success */
+	ut_assertok(uclass_first_device_err(UCLASS_I2S, &dev));
+	data[0] = 1;
+	data[1] = 4;
+	data[2] = 6;
+	ut_assertok(i2s_tx_data(dev, data, ARRAY_SIZE(data)));
+	ut_asserteq(11, sandbox_get_i2s_sum(dev));
+	ut_assertok(i2s_tx_data(dev, data, 1));
+	ut_asserteq(12, sandbox_get_i2s_sum(dev));
+
+	return 0;
+}
+DM_TEST(dm_test_i2s, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);