ARM: uniphier: move spl_boot_mode() to a separate file

The spl_boot_mode() is unrelated to the other code in this file.
Besides, this function is only called from common/spl/spl_mmc.c,
so it is reasonable to guard with CONFIG_SPL_MMC_SUPPORT.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/mmc-boot-mode.c b/arch/arm/mach-uniphier/mmc-boot-mode.c
new file mode 100644
index 0000000..d60c578
--- /dev/null
+++ b/arch/arm/mach-uniphier/mmc-boot-mode.c
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016 Socionext Inc.
+ *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <mmc.h>
+#include <spl.h>
+
+u32 spl_boot_mode(const u32 boot_device)
+{
+	struct mmc *mmc;
+
+	/*
+	 * work around a bug in the Boot ROM of PH1-sLD3, LD4, Pro4, and sLD8:
+	 *
+	 * The boot ROM in these SoCs breaks the PARTITION_CONFIG [179] of
+	 * Extended CSD register; when switching to the Boot Partition 1, the
+	 * Boot ROM should issue the SWITCH command (CMD6) with Set Bits for
+	 * the Access Bits, but in fact it uses Write Byte for the Access Bits.
+	 * As a result, the BOOT_PARTITION_ENABLE field of the PARTITION_CONFIG
+	 * is lost.  This bug was fixed for PH1-Pro5 and later SoCs.
+	 *
+	 * Fixup mmc->part_config here because it is used to determine the
+	 * partition which the U-Boot image is read from.
+	 */
+	mmc = find_mmc_device(0);
+	mmc->part_config &= ~EXT_CSD_BOOT_PART_NUM(PART_ACCESS_MASK);
+	mmc->part_config |= EXT_CSD_BOOT_PARTITION_ENABLE;
+
+	return MMCSD_MODE_EMMCBOOT;
+}