dm: cache: Create a uclass for cache

The cache UCLASS will be used for configure settings that can be found
in a CPU's L2 cache controller.

Add a uclass and a test for cache.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>

drivers/cache/sandbox_cache.c

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Intel Corporation <www.intel.com>
+ */
+
+#include <common.h>
+#include <cache.h>
+#include <dm.h>
+#include <errno.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int sandbox_get_info(struct udevice *dev, struct cache_info *info)
+{
+	info->base = 0x11223344;
+
+	return 0;
+}
+
+static const struct cache_ops sandbox_cache_ops = {
+	.get_info	= sandbox_get_info,
+};
+
+static const struct udevice_id sandbox_cache_ids[] = {
+	{ .compatible = "sandbox,cache" },
+	{ }
+};
+
+U_BOOT_DRIVER(cache_sandbox) = {
+	.name		= "cache_sandbox",
+	.id		= UCLASS_CACHE,
+	.of_match	= sandbox_cache_ids,
+	.ops		= &sandbox_cache_ops,
+};