xtensa: add support for the xtensa processor architecture [2/2]

The Xtensa processor architecture is a configurable, extensible,
and synthesizable 32-bit RISC processor core provided by Tensilica, inc.

This is the second part of the basic architecture port, adding the
'arch/xtensa' directory and a readme file.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/xtensa/include/asm/global_data.h b/arch/xtensa/include/asm/global_data.h
new file mode 100644
index 0000000..4569345
--- /dev/null
+++ b/arch/xtensa/include/asm/global_data.h
@@ -0,0 +1,20 @@
+/*
+ * (C) Copyright 2007, Tensilica Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef	_XTENSA_GBL_DATA_H
+#define _XTENSA_GBL_DATA_H
+
+/* Architecture-specific global data */
+
+struct arch_global_data {
+	unsigned long cpu_clk;
+};
+
+#include <asm-generic/global_data.h>
+
+#define DECLARE_GLOBAL_DATA_PTR     extern gd_t *gd
+
+#endif	/* _XTENSA_GBL_DATA_H */