omap5: Definitions for SYS_BOOT-based fallback boot device selection

This introduces code to read the value of the SYS_BOOT pins on the OMAP5, as
well as the memory-preferred scheme for the interpretation of each value.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>

arch/arm/cpu/armv7/omap5/Makefile

@@ -5,6 +5,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+obj-y	+= boot.o
 obj-y	+= hwinit.o
 obj-y	+= emif.o
 obj-y	+= sdram.o

arch/arm/cpu/armv7/omap5/boot.c

@@ -0,0 +1,46 @@
+/*
+ * OMAP5 boot
+ *
+ * Copyright (C) 2015 Paul Kocialkowski <contact@paulk.fr>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/omap_common.h>
+#include <spl.h>
+
+static u32 boot_devices[] = {
+#if defined(CONFIG_DRA7XX) || defined(CONFIG_AM57XX)
+	BOOT_DEVICE_MMC2,
+	BOOT_DEVICE_NAND,
+	BOOT_DEVICE_MMC1,
+	BOOT_DEVICE_SATA,
+	BOOT_DEVICE_XIP,
+	BOOT_DEVICE_XIP,
+	BOOT_DEVICE_SPI,
+	BOOT_DEVICE_SPI,
+#else
+	BOOT_DEVICE_MMC2,
+	BOOT_DEVICE_NAND,
+	BOOT_DEVICE_MMC1,
+	BOOT_DEVICE_SATA,
+	BOOT_DEVICE_XIP,
+	BOOT_DEVICE_MMC2,
+	BOOT_DEVICE_XIPWAIT,
+#endif
+};
+
+u32 omap_sys_boot_device(void)
+{
+	u32 sys_boot;
+
+	/* Grab the first 4 bits of the status register for SYS_BOOT. */
+	sys_boot = readl((u32 *) (*ctrl)->control_status) & ((1 << 4) - 1);
+
+	if (sys_boot >= (sizeof(boot_devices) / sizeof(u32)))
+		return BOOT_DEVICE_NONE;
+
+	return boot_devices[sys_boot];
+}