zephyr: Bring in the Zephyr build

Add support for building mcuboot as a Zephyr application.  This is
copied from the iotboot repo with some minor reorganization to work with
the mcuboot directory layout.
diff --git a/zephyr/src/flash_map.c b/zephyr/src/flash_map.c
new file mode 100644
index 0000000..aadf13a
--- /dev/null
+++ b/zephyr/src/flash_map.c
@@ -0,0 +1,149 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <zephyr.h>
+#include <misc/printk.h>
+#include <flash.h>
+
+#include <flash_map/flash_map.h>
+#include <hal/hal_flash.h>
+#include <sysflash/sysflash.h>
+
+extern struct device *boot_flash_device;
+
+/*
+ * The flash area describes essentially the partition table of the
+ * flash.  In this case, it starts with FLASH_AREA_IMAGE_0.
+ */
+static const struct flash_area part_map[] = {
+	{
+		.fa_id = FLASH_AREA_IMAGE_0,
+		.fa_off = 0x20000,
+		.fa_size = 0x20000,
+	},
+	{
+		.fa_id = FLASH_AREA_IMAGE_1,
+		.fa_off = 0x40000,
+		.fa_size = 0x20000,
+	},
+	{
+		.fa_id = FLASH_AREA_IMAGE_SCRATCH,
+		.fa_off = 0x60000,
+		.fa_size = 0x20000,
+	},
+};
+
+/*
+ * The K64F has a simple 1MB of uniform 4KB sectors.  Initially, we'll
+ * use the same partition layout as the Carbon board to make
+ * development easier.
+ */
+
+/*
+ * `open` a flash area.  The `area` in this case is not the individual
+ * sectors, but describes the particular flash area in question.
+ */
+int flash_area_open(uint8_t id, const struct flash_area **area)
+{
+	int i;
+	printk("%s: area %d\n", __func__, id);
+
+	for (i = 0; i < ARRAY_SIZE(part_map); i++) {
+		if (id == part_map[i].fa_id)
+			break;
+	}
+	if (i == ARRAY_SIZE(part_map))
+		return -1;
+
+	*area = &part_map[i];
+	return 0;
+}
+
+/*
+ * Nothing to do on close.
+ */
+void flash_area_close(const struct flash_area *area)
+{
+}
+
+int flash_area_read(const struct flash_area *area, uint32_t off, void *dst,
+		    uint32_t len)
+{
+	// printk("%s: area=%d, off=%x, len=%x\n", __func__, area->fa_id, off, len);
+	return flash_read(boot_flash_device, area->fa_off + off, dst, len);
+}
+
+int flash_area_write(const struct flash_area *area, uint32_t off, const void *src,
+		     uint32_t len)
+{
+	printk("%s: area=%d, off=%x, len=%x\n", __func__, area->fa_id, off, len);
+	return flash_write(boot_flash_device, area->fa_off + off, src, len);
+}
+
+int flash_area_erase(const struct flash_area *area, uint32_t off, uint32_t len)
+{
+	printk("%s: area=%d, off=%x, len=%x\n", __func__, area->fa_id, off, len);
+	return flash_erase(boot_flash_device, area->fa_off + off, len);
+}
+
+uint8_t flash_area_align(const struct flash_area *area)
+{
+	return hal_flash_align(area->fa_id);
+}
+
+/*
+ * This depends on the mappings defined in sysflash.h, and assumes
+ * that slot 0, slot 1, and the scratch area area contiguous.
+ */
+int flash_area_id_from_image_slot(int slot)
+{
+	return slot + FLASH_AREA_IMAGE_0;
+}
+
+/*
+ * Lookup the sector map for a given flash area.  This should fill in
+ * `ret` with all of the sectors in the area.  `*cnt` will be set to
+ * the storage at `ret` and should be set to the final number of
+ * sectors in this area.
+ */
+int flash_area_to_sectors(int idx, int *cnt, struct flash_area *ret)
+{
+	uint32_t off;
+
+	printk("%s: lookup area %d\n", __func__, idx);
+	/*
+	 * This simple layout has uniform slots, so just fill in the
+	 * right one.
+	 */
+	if (idx < FLASH_AREA_IMAGE_0 || idx > FLASH_AREA_IMAGE_SCRATCH)
+		return -1;
+
+	if (*cnt < 1)
+		return -1;
+
+	off = (idx - FLASH_AREA_IMAGE_0 + 1) * 0x20000;
+
+	ret->fa_id = idx;
+	ret->fa_device_id = 0;
+	ret->pad16 = 0;
+	ret->fa_off = off;
+	ret->fa_size = 0x20000;
+
+	return 0;
+}