sandbox: Add basic SPL implementation

Add an sandbox implementation for the generic SPL framework. This supports
locating and running U-Boot proper.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/Makefile

@@ -8,6 +8,7 @@
 #
 
 obj-y	:= cpu.o os.o start.o state.o
+obj-$(CONFIG_SPL_BUILD)	+= spl.o
 obj-$(CONFIG_ETH_SANDBOX_RAW)	+= eth-raw-os.o
 obj-$(CONFIG_SANDBOX_SDL)	+= sdl.o
 

arch/sandbox/cpu/spl.c

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016 Google, Inc
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <os.h>
+#include <asm/spl.h>
+#include <asm/state.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+void board_init_f(ulong flag)
+{
+	struct sandbox_state *state = state_get_current();
+
+	gd->arch.ram_buf = state->ram_buf;
+	gd->ram_size = state->ram_size;
+}
+
+u32 spl_boot_device(void)
+{
+	return BOOT_DEVICE_BOARD;
+}
+
+void spl_board_announce_boot_device(void)
+{
+	char fname[256];
+	int ret;
+
+	ret = os_find_u_boot(fname, sizeof(fname));
+	if (ret) {
+		printf("(%s not found, error %d)\n", fname, ret);
+		return;
+	}
+	printf("%s\n", fname);
+}
+
+int spl_board_load_image(void)
+{
+	char fname[256];
+	int ret;
+
+	ret = os_find_u_boot(fname, sizeof(fname));
+	if (ret)
+		return ret;
+
+	/* Hopefully this will not return */
+	return os_spl_to_uboot(fname);
+}

arch/sandbox/include/asm/spl.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2016 Google, Inc
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __asm_spl_h
+#define __asm_spl_h
+
+#define CONFIG_SPL_BOARD_LOAD_IMAGE
+
+/**
+ * Board-specific load method for boards that have a special way of loading
+ * U-Boot, which does not fit with the existing SPL code.
+ *
+ * @return 0 on success, negative errno value on failure.
+ */
+int spl_board_load_image(void);
+
+enum {
+	BOOT_DEVICE_BOARD,
+};
+
+#endif