boot/espressif: Update main.c to call init and loader functions

Add ESP specific loader code to load host application

Signed-off-by: Shubham Kulkarni <shubham.kulkarni@espressif.com>
diff --git a/boot/espressif/port/esp_loader.c b/boot/espressif/port/esp_loader.c
new file mode 100644
index 0000000..878dd55
--- /dev/null
+++ b/boot/espressif/port/esp_loader.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2021 Espressif Systems (Shanghai) Co., Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <string.h>
+#include <soc/soc.h>
+#include <soc/dport_reg.h>
+#include "soc/soc_memory_layout.h"
+#include <bootloader_flash.h>
+#include <bootloader_flash_priv.h>
+
+#include "esp32/rom/cache.h"
+#include "esp32/rom/efuse.h"
+#include "esp32/rom/ets_sys.h"
+#include "esp32/rom/spi_flash.h"
+#include "esp32/rom/crc.h"
+#include "esp32/rom/rtc.h"
+#include "esp32/rom/gpio.h"
+#include "esp32/rom/uart.h"
+
+#include <esp_loader.h>
+#include <bootutil/fault_injection_hardening.h>
+#include <flash_map_backend/flash_map_backend.h>
+#include <mcuboot_config/mcuboot_logging.h>
+
+#define ESP_LOAD_HEADER_MAGIC 0xace637d3   /* Magic is derived from sha256sum of espmcuboot */
+
+/*
+ * Load header that should be a part of application image.
+ */
+typedef struct image_load_header {
+    uint32_t header_magic;          /* Magic for load header */
+    uint32_t entry_addr;            /* Application entry address */
+    uint32_t iram_dest_addr;        /* Destination address(VMA) for IRAM region */
+    uint32_t iram_flash_offset;     /* Flash offset(LMA) for start of IRAM region */
+    uint32_t iram_size;             /* Size of IRAM region */
+    uint32_t dram_dest_addr;        /* Destination address(VMA) for DRAM region */
+    uint32_t dram_flash_offset;     /* Flash offset(LMA) for start of DRAM region */
+    uint32_t dram_size;             /* Size of DRAM region */
+} image_load_header_t;
+
+static int load_segment(const struct flash_area *fap, uint32_t data_addr, uint32_t data_len, uint32_t load_addr)
+{
+    const uint32_t *data = (const uint32_t *)bootloader_mmap((fap->fa_off + data_addr), data_len);
+    if (!data) {
+        MCUBOOT_LOG_ERR("%s: Bootloader nmap failed", __func__);
+        return -1;
+    }
+    memcpy((void *)load_addr, data, data_len);
+    bootloader_munmap(data);
+    return 0;
+}
+
+void esp_app_image_load(int slot, unsigned int hdr_offset)
+{
+    const struct flash_area *fap;
+    int area_id;
+    int rc;
+
+    image_load_header_t load_header = {0};
+
+    area_id = flash_area_id_from_image_slot(slot);
+    rc = flash_area_open(area_id, &fap);
+    if (rc != 0) {
+        MCUBOOT_LOG_ERR("%s: flash_area_open failed with %d", __func__, rc);
+    }
+
+    const uint32_t *data = (const uint32_t *)bootloader_mmap((fap->fa_off + hdr_offset), sizeof(image_load_header_t));
+    memcpy((void *)&load_header, data, sizeof(image_load_header_t));
+    bootloader_munmap(data);
+
+    if (load_header.header_magic != ESP_LOAD_HEADER_MAGIC) {
+        MCUBOOT_LOG_ERR("Load header magic verification failed. Aborting");
+        FIH_PANIC;
+    }
+
+    if (!esp_ptr_in_iram((void *)load_header.iram_dest_addr) || !esp_ptr_in_iram((void *)(load_header.iram_dest_addr + load_header.iram_size))) {
+        MCUBOOT_LOG_ERR("IRAM region in load header is not valid. Aborting");
+        FIH_PANIC;
+    }
+
+    if (!esp_ptr_in_dram((void *)load_header.dram_dest_addr) || !esp_ptr_in_dram((void *)load_header.dram_dest_addr + load_header.dram_size)) {
+        MCUBOOT_LOG_ERR("DRAM region in load header is not valid. Aborting");
+        FIH_PANIC;
+    }
+
+    if (!esp_ptr_in_iram((void *)load_header.entry_addr)) {
+        MCUBOOT_LOG_ERR("Application entry point is not in IRAM. Aborting");
+        FIH_PANIC;
+    }
+
+    MCUBOOT_LOG_INF("DRAM segment: start=0x%x, size=0x%x, vaddr=0x%x", load_header.dram_flash_offset, load_header.dram_size, load_header.dram_dest_addr);
+    load_segment(fap, load_header.dram_flash_offset, load_header.dram_size, load_header.dram_dest_addr);
+
+    MCUBOOT_LOG_INF("IRAM segment: start=0x%x, size=0x%x, vaddr=0x%x", load_header.iram_flash_offset, load_header.iram_size, load_header.iram_dest_addr);
+    load_segment(fap, load_header.iram_flash_offset, load_header.iram_size, load_header.iram_dest_addr);
+
+    MCUBOOT_LOG_INF("start=0x%x", load_header.entry_addr);
+    uart_tx_wait_idle(0);
+    void *start = (void *) load_header.entry_addr;
+    ((void (*)(void))start)(); /* Call to application entry address should not return */
+    FIH_PANIC;
+}