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>

include/cache.h

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Intel Corporation <www.intel.com>
+ */
+
+#ifndef __CACHE_H
+#define __CACHE_H
+
+/*
+ * Structure for the cache controller
+ */
+struct cache_info {
+	phys_addr_t base; /* Base physical address of cache device. */
+};
+
+struct cache_ops {
+	/**
+	 * get_info() - Get basic cache info
+	 *
+	 * @dev:	Device to check (UCLASS_CACHE)
+	 * @info:	Place to put info
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*get_info)(struct udevice *dev, struct cache_info *info);
+};
+
+#define cache_get_ops(dev)	((struct cache_ops *)(dev)->driver->ops)
+
+/**
+ * cache_get_info() - Get information about a cache controller
+ *
+ * @dev:	Device to check (UCLASS_CACHE)
+ * @info:	Returns cache info
+ * @return 0 if OK, -ve on error
+ */
+int cache_get_info(struct udevice *dev, struct cache_info *info);
+
+#endif