Support for NXP S32K14XX

[dgarske]

Summary

This PR adds wolfBoot support for the NXP S32K1xx family of automotive-grade Cortex-M4F microcontrollers (S32K142, S32K144, S32K146, S32K148). The implementation is a bare-metal port requiring no external SDK.

Target Hardware

• Tested on: NXP S32K142 (256KB Flash, 32KB SRAM)
• Architecture: ARM Cortex-M4F at up to 112 MHz (HSRUN) or 80 MHz (RUN mode)
• Flash characteristics: 2KB sectors, 8-byte (phrase) programming unit

Files Added

File	Description
hal/s32k1xx.c	HAL implementation with flash, clock, UART, and watchdog drivers
hal/s32k1xx.h	Register definitions for S32K1xx peripherals
hal/s32k1xx.ld	Linker script for wolfBoot bootloader
config/examples/nxp-s32k142.config	Example configuration for S32K142
test-app/app_s32k1xx.c	Test application with LED toggle and UART output
test-app/ARM-s32k1xx.ld	Linker script for test application

Memory Layout (S32K142 - 256KB Flash)

Region	Address Range	Size
Bootloader	0x00000000 - 0x0000BFFF	48 KB
Boot Partition	0x0000C000 - 0x00024FFF	100 KB
Update Partition	0x00025000 - 0x0003DFFF	100 KB
Swap Sector	0x0003E000 - 0x0003E7FF	2 KB

Key Features

• Bare-metal implementation: No NXP SDK dependency required
• Flash driver: Full support for flash erase (2KB sectors) and program (8-byte phrase) operations
• Clock configuration: Defaults to RUN mode with FIRC (48 MHz internal RC oscillator)
• Debug UART: LPUART1 output on PTC6/PTC7 at 115200 baud
• Watchdog support: Configurable watchdog with LPO clock source
• Flash Configuration Field (FCF): Properly configured at 0x400-0x40F

Build Instructions

# Copy configuration
cp config/examples/nxp-s32k142.config .config

# Build wolfBoot
make clean && make

# Build test application
make test-app/image.bin

Programming

Supports multiple debug probe options:

• PEMicro (recommended for S32K EVB boards)
• J-Link
• OpenSDA

Documentation

Comprehensive documentation added to docs/Targets.md including:

• Configuration options
• Clock modes (RUN/HSRUN)
• Debug UART setup
• Programming and debugging instructions
• GDB debugging tips

Future Enhancements (TODO)

• SPLL + SOSC support for true 112 MHz HSRUN operation
• CSEc hardware crypto acceleration integration
• FlexNVM/EEPROM support
• Support for larger S32K144/146/148 variants
• CAN/LIN bootloader for automotive firmware updates

Testing

• Verified boot and update flow on S32K142 EVB
• Tested with ECC256/SHA256 signature verification
• UART debug output confirmed working