boards/z80/ez80/z20x/configs/w25boot/defconfig: Increase size of serial Tx buffer.
boards/z80/ez80/z20x/src/w25_main.c: Add some fflush() in necessary places. Greatly improves the usability of the UI.
boards/z80/ez80/z20x/README.txt: Trival update to README
drivers/serial/serial.c and tcdrain.c: Correct some typos.
- boards/z80/ez80/z20x/scripts/z20x_*.linkcmd: Reduce from 4 to 1 wait state. That i sufficient because of the slow clocking of the eZ80F92
- boards/z80/ez80/z20x/src/w25_main.c: Replace CRC algorithm with simple, less time consuming check sum.
- boards/z80/ez80/z20x/configs/nsh: Rename the nsh_ram configuration to just nsh
- boards/z80/ez80/z80x/configs/hello: Add simpler program to make debugging the loader easier.
boards/z80/ez80/z20x: Increase RX buffer size to 4Kb, reduce BAUD to 2400 in w25boot configuration
arch/z80/src/ez80/ez80_serial.c: Reduce Rx FIFO trigger level for eZ80F92 to 1 so that will respond more quickly to incoming data.
The SD boot loader was not satisfactory because 1) the SD slot is on an optional board and, hence, cannot be part of a fundamental solution. And 2) it is too big.
The only storage on borard is the Winbond W25 SPI-bsed FLASH. This commit adds support for a bootload to 1) read code in HEX format from a serial port and write it to the W25 FLASH, or 2) read code in binary form from the W25 FLASH into SRAM and execute the loaded program.
boards/z80/ez80/z20x/configs: Added w25boot configuration
boards/z80/ez80/z20x/src: Add bootloader logic, w25_main.c. Add logic to manage shared SRAM memory map so that the loaded program does not clobber the bootloader memory. Add logic to recover the bootloader memory into the heap after the loaded program as started.
boards/z80/ez80/z20x/scripts: Rework scripts and configuration to support a bootloader and program build. The boolloader cannot use all of SRAM; the program must not clobber the SRAM region used by the bootloader.
