esp32: Improve selection of the bootloader being used on Kconfig

- A pre-built IDF bootloader is used by default;
- `ESP32_PARTITION_TABLE` requires the IDF bootloader to be built
from sources.
- Native MCUboot also can be used to boot the device. It will be
built from sources and depends on !ESP32_PARTITION_TABLE.

arch/xtensa/src/esp32/Bootloader.mk

@@ -192,15 +192,7 @@ else ifeq ($(CONFIG_ESP32_BOOTLOADER_DOWNLOAD_PREBUILT),y)
 BOOTLOADER_VERSION = latest
 BOOTLOADER_URL     = https://github.com/espressif/esp-nuttx-bootloader/releases/download/$(BOOTLOADER_VERSION)
 
-ifeq ($(CONFIG_ESP32_APP_FORMAT_MCUBOOT),y)
-
-bootloader:
-	$(call DOWNLOAD,$(BOOTLOADER_URL),mcuboot-esp32.bin,$(TOPDIR)/mcuboot-esp32.bin)
-
-clean_bootloader:
-	$(call DELFILE,$(TOPDIR)/mcuboot-esp32.bin)
-
-else ifeq ($(CONFIG_ESP32_APP_FORMAT_LEGACY),y)
+ifeq ($(CONFIG_ESP32_APP_FORMAT_LEGACY),y)
 
 bootloader:
 	$(call DOWNLOAD,$(BOOTLOADER_URL),bootloader-esp32.bin,$(TOPDIR)/bootloader-esp32.bin)

arch/xtensa/src/esp32/Kconfig

@@ -1870,6 +1870,7 @@ comment "Partition Table Configuration"
 config ESP32_PARTITION_TABLE
 	bool "Create MTD partitions from Partition Table"
 	default n
+	select ESP32_BOOTLOADER_BUILD_FROM_SOURCE
 	---help---
 		Decode partition table and initialize partitions as MTD.
 
@@ -2443,42 +2444,28 @@ config ESP32_HAVE_OTA_PARTITION
 	bool
 	default n
 
-menu "Application Image Configuration"
-
-choice
-	prompt "Application Image Format"
-	default ESP32_APP_FORMAT_LEGACY
-	---help---
-		Depending on the chosen 2nd stage bootloader, the application may
-		be required to be perform a specific startup routine. Furthermore,
-		the image binary must be formatted according to the definition from
-		the 2nd stage bootloader.
+menu "Bootloader and Image Configuration"
 
 config ESP32_APP_FORMAT_LEGACY
-	bool "Legacy format"
+	bool
+	default y if !ESP32_APP_FORMAT_MCUBOOT
+	depends on !ESP32_APP_FORMAT_MCUBOOT
 	---help---
 		This is the legacy application image format, as supported by the ESP-IDF
 		2nd stage bootloader.
 
 config ESP32_APP_FORMAT_MCUBOOT
-	bool "MCUboot-bootable format"
+	bool "Enable MCUboot-bootable format"
 	depends on !MCUBOOT_BOOTLOADER
 	select ESP32_HAVE_OTA_PARTITION
+	select ESP32_BOOTLOADER_BUILD_FROM_SOURCE
 	---help---
-		The ESP32 port of MCUboot supports the loading of unsegmented firmware
-		images.
-
-endchoice # Application Image Format
-
-choice
-	prompt "Source for bootloader binaries"
-	default ESP32_BOOTLOADER_DOWNLOAD_PREBUILT
-	---help---
-		Select the action to be taken by the build system for the
-		"make bootloader" target.
+		Enables the Espressif port of MCUboot to be used as 2nd stage bootloader.
 
 config ESP32_BOOTLOADER_DOWNLOAD_PREBUILT
-	bool "Download prebuilt binaries"
+	bool
+	default y if !ESP32_BOOTLOADER_BUILD_FROM_SOURCE
+	depends on !ESP32_BOOTLOADER_BUILD_FROM_SOURCE
 	---help---
 		The build system will download the prebuilt binaries from
 		https://github.com/espressif/esp-nuttx-bootloader according to the chosen
@@ -2492,8 +2479,6 @@ config ESP32_BOOTLOADER_BUILD_FROM_SOURCE
 		custom bootloader according to the chosen Application Image Format
 		(ESP32_APP_FORMAT_LEGACY or ESP32_APP_FORMAT_MCUBOOT) and partition information.
 
-endchoice
-
 choice
 	prompt "Target slot for image flashing"
 	default ESP32_ESPTOOL_TARGET_PRIMARY
@@ -2529,11 +2514,37 @@ config ESP32_APP_MCUBOOT_HEADER_SIZE
 	default 32
 	depends on ESP32_APP_FORMAT_MCUBOOT
 
-config ESP32_PARTITION_TABLE_OFFSET
-	hex "Partition Table offset"
+config ESP32_PARTITION_TABLE_OFFSET_DEFAULT
+	hex
 	default 0x8000
 	depends on ESP32_APP_FORMAT_LEGACY
 
+config ESP32_CUSTOM_PARTITION_TABLE_OFFSET
+	bool "Customize partition table offset"
+	default n
+	depends on ESP32_APP_FORMAT_LEGACY
+	select ESP32_BOOTLOADER_BUILD_FROM_SOURCE
+	---help---
+		Enable to select the offset of the partition table in the flash.
+
+if ESP32_CUSTOM_PARTITION_TABLE_OFFSET
+
+config ESP32_PARTITION_TABLE_OFFSET
+	hex "Partition Table offset"
+	default ESP32_PARTITION_TABLE_OFFSET_DEFAULT
+	depends on ESP32_APP_FORMAT_LEGACY
+
+endif # ESP32_CUSTOM_PARTITION_TABLE_OFFSET
+
+if !ESP32_CUSTOM_PARTITION_TABLE_OFFSET
+
+config ESP32_PARTITION_TABLE_OFFSET
+	hex
+	default ESP32_PARTITION_TABLE_OFFSET_DEFAULT
+	depends on ESP32_APP_FORMAT_LEGACY
+
+endif # !ESP32_CUSTOM_PARTITION_TABLE_OFFSET
+
 if BUILD_PROTECTED
 
 config ESP32_USER_IMAGE_OFFSET

boards/xtensa/esp32/esp32-devkitc/configs/mcuboot_nsh/defconfig

@@ -20,7 +20,6 @@ CONFIG_ARCH_XTENSA=y
 CONFIG_BOARD_LOOPSPERMSEC=16717
 CONFIG_BUILTIN=y
 CONFIG_ESP32_APP_FORMAT_MCUBOOT=y
-CONFIG_ESP32_BOOTLOADER_BUILD_FROM_SOURCE=y
 CONFIG_ESP32_UART0=y
 CONFIG_FS_PROCFS=y
 CONFIG_HAVE_CXX=y

boards/xtensa/esp32/esp32-devkitc/configs/mcuboot_update_agent/defconfig

@@ -27,7 +27,6 @@ CONFIG_DEBUG_SYMBOLS=y
 CONFIG_DRIVERS_IEEE80211=y
 CONFIG_DRIVERS_WIRELESS=y
 CONFIG_ESP32_APP_FORMAT_MCUBOOT=y
-CONFIG_ESP32_BOOTLOADER_BUILD_FROM_SOURCE=y
 CONFIG_ESP32_SPIFLASH=y
 CONFIG_ESP32_UART0=y
 CONFIG_ESP32_WIFI=y