boards: nxp: frdm_mcxn947 and mcx_n9xx_evk: boot directly from QSPI flash

[DerekSnell]

The ROM bootloader has the option to boot from external QSPI flash on the FlexSPI instead of internal flash. Configures QSPI board variants to boot directly from QSPI. Secondary bootloader is no longer required. Moves the MCUboot boot_partition to QSPI flash.

Placing the MCUboot boot_partition in the QSPI flash depends on mcu-tools/mcuboot#2319

[github-actions]

The following west manifest projects have changed revision in this Pull Request:

Name	Old Revision	New Revision	Diff
hal_nxp	zephyrproject-rtos/hal_nxp@d0e49d6	zephyrproject-rtos/hal_nxp@73d478f (master)	zephyrproject-rtos/hal_nxp@d0e49d63..73d478f7

✅ All manifest checks OK

Note: This message is automatically posted and updated by the Manifest GitHub Action.

[decsny]

DNM until #90566 merges, otherwise CI breaks, thanks

please update manifest

[DerekSnell]

#90566 merged, HAL_NXP merged, manifest updated and this PR rebased, and DNM label removed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[DerekSnell]

I am documenting this here for those who prefer using the previous hybrid flash use-case. This PR enabled booting directly from external QSPI flash. Before this PR merged, XIP from QSPI was supported using both internal and external flash, what I call here the hybrid use-case. This hybrid method boots from internal flash with the MCUboot boot_partition. Then MCUboot enables the FlexSPI interface and configures for the external QSPI flash, and then loads the app to XIP from QSPI. However, MCUboot was reverted which broke this hybrid use-case. But the hybrid option is no longer needed, because now the QSPI board variant will boot directly from QSPI, and no longer requires MCUboot.

If the hybrid flash use-case is preferred, these steps work for me. These steps are written for the frdm_mcxn947 board. MCUboot is built and flashed in internal flash. The blinky app is built for the frdm_mcxn947//cpu0/qspi board variant and flashed to the external QSPI. These steps are based on c7e36f0 :

1. Program the PFR to boot from internal flash. This is the default setting of the MCXN947 SOC. But if the SOC was previously programmed to boot from external QSPI flash, it needs to be programmed back. For more details, see Programming the ROM bootloader for external QSPI.
2. In the MCUboot repo, revert mcu-tools/mcuboot@8131548
3. Apply the attached patch mcuboot-hybrid-flash-overlay.patch.txt to the Zephyr repo. This adds mcuboot-hybrid-flash.overlay to the FRDM_MCXN947 board folder.
4. Build and flash MCUboot and the blinky sample using the commands below:

west build -b frdm_mcxn947//cpu0 ../bootloader/mcuboot/boot/zephyr -d ../hybrid_mcb_n947 --pristine -- -DDTC_OVERLAY_FILE="../../../../zephyr/boards/nxp/frdm_mcxn947/mcuboot-hybrid-flash.overlay" 
west build -b frdm_mcxn947//cpu0/qspi samples/basic/blinky -d ../hybrid_blinky_n947 --pristine -- -DCONFIG_BOOTLOADER_MCUBOOT=y -DDTC_OVERLAY_FILE="../../boards/nxp/frdm_mcxn947/mcuboot-hybrid-flash.overlay" -DCONFIG_MCUBOOT_SIGNATURE_KEY_FILE=\"bootloader/mcuboot/root-rsa-2048.pem\" 
west flash -d ../hybrid_mcb_n947 -r jlink
west flash -d ../hybrid_blinky_n947 -r jlink

The debug console output shows MCUboot boots and loads the blinky sample:

*** Booting MCUboot v2.2.0-rc1-17-gbcd9614727ab ***
*** Using Zephyr OS build v4.1.0-4901-gc7e36f01696a ***
I: Starting bootloader
I: Image index: 0, Swap type: none
I: Bootloader chainload address offset: 0x0
I: Image version: v0.0.0
I: Jumping to the first image slot
*** Booting Zephyr OS build v4.1.0-4901-gc7e36f01696a ***
LED state: OFF
LED state: ON