Unset the flash chip's WP pin on erase

Usually firmware pulls the WP pin of the flash chip low to protect the
flash chip's content. Set it to high during erase/write.

Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>

rtdmultiprog.py

@@ -135,14 +135,17 @@ def get_flash_id():
 
 def erase_flash():
     print("Erasing... ", end='')
+    write_reg(0xe3, read_reg(0xe3)[0] | (1<<2)) # deassert WP pin
     isp_custom_instruction(CI_WRITE_AFTER_WREN, WRSR, 0, 1, 0x00) # Unprotect the flash
     isp_custom_instruction(CI_ERASE, ERAS, 0, 0, 0x00)            # Erase the flash
     isp_custom_instruction(CI_WRITE_AFTER_WREN, WRSR, 0, 1, 0x1C) # Protect the flash
+    write_reg(0xe3, read_reg(0xe3)[0] & ~(1<<2)) # assert WP pin
     print("done")
 
 def program_flash(data, progress_callback=lambda s, e, c: None):
     print(f"Will write {len(data) / 1024:.1f} KiB")
 
+    write_reg(0xe3, read_reg(0xe3)[0] | (1<<2)) # deassert WP pin
     isp_custom_instruction(CI_WRITE_AFTER_WREN, WRSR, 0, 1, 0x00) # Unprotect the flash
     pages = list(div_to_chunks(data, PAGE_SIZE))
     for page_n, page in enumerate(pages):
@@ -165,6 +168,7 @@ def program_flash(data, progress_callback=lambda s, e, c: None):
 
     poll(lambda: not read_reg (0x6F)[0] & 0x40, "Programming done timeout")
     isp_custom_instruction(CI_WRITE_AFTER_WREN, WRSR, 0, 1, 0x1C)  # Protect the flash
+    write_reg(0xe3, read_reg(0xe3)[0] & ~(1<<2)) # assert WP pin
 
     data_crc = calculate_crc(data)
     chip_crc = isp_get_crc(0, len(data) - 1)