spl: Add support for passing handoff info to U-Boot proper

There is some basic informaton that SPL normally wants to pass through to
U-Boot, such as the SDRAM size and bank information.

Mkae use of the new bloblist structure for this. Add a new 'handoff' blob
which is set up in SPL and passed to U-Boot proper. Also adda  test for
sandbox_spl that checks that this works correctly and a new 'sb' command
to show the information passed from SPL.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

include/handoff.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Passing basic information from SPL to U-Boot proper
+ *
+ * Copyright 2018 Google, Inc
+ */
+
+#ifndef __HANDOFF_H
+#define __HANDOFF_H
+
+#if CONFIG_IS_ENABLED(HANDOFF)
+
+#include <asm/handoff.h>
+
+/**
+ * struct spl_handoff - information passed from SPL to U-Boot proper
+ *
+ * @ram_size: Value to use for gd->ram_size
+ */
+struct spl_handoff {
+	struct arch_spl_handoff arch;
+	u64 ram_size;
+#ifdef CONFIG_NR_DRAM_BANKS
+	struct {
+		u64 start;
+		u64 size;
+	} ram_bank[CONFIG_NR_DRAM_BANKS];
+#endif
+};
+
+void handoff_save_dram(struct spl_handoff *ho);
+void handoff_load_dram_size(struct spl_handoff *ho);
+void handoff_load_dram_banks(struct spl_handoff *ho);
+#endif
+
+#endif