mule-attiny: i2c_flash: implement bl_data reading from flashloader

After entering the flashloader mode, clearing the boot request gpio
sets the flashloader into read-only mode where the flashing tool can read
bootloader data through i2c (i2c-write ops are ignored).

This data contain:
* Bootloader version

This tool will print out all bootloader data to the console.

Relates-to: RNG-147

Signed-off-by: Farouk Bouabid <farouk.bouabid@theobroma-systems.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py b/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
index c867558..7beea78 100755
--- a/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
+++ b/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
@@ -11,6 +11,9 @@ from time import sleep
 from argparse import ArgumentParser
 import pathlib
 import logging
+from abc import abstractmethod
+from enum import IntEnum
+
 
 # Bootloader I2C slave address
 BL_I2C_DEV = 0x6f   # Reuse isl1208 address
@@ -82,6 +85,83 @@ class BootModeController:
             raise Exception("UPDI Reset command failed!")
 
 
+class BLHdrID(IntEnum):
+    VERSION = 0
+    # Add other bootloader header IDs here
+
+
+def get_blhdr(blhdr):
+    id = (blhdr & (0b111 << 5))
+    if id == BLHdrID.VERSION:
+        return BLVersionHdr(blhdr)
+    # Add other bootloader header IDs here
+    raise Exception(f"Unknown {id} ID for payload header")
+
+
+class BLHdr():
+    def __init__(self, hdr):
+        self.hdr = hdr
+
+    @abstractmethod
+    def len(self):
+        """Returns length of payload excluding header"""
+        pass
+
+    @abstractmethod
+    def payload_class(self):
+        """Returns the class to use for representing the data following the header"""
+        pass
+
+
+class BLVersionHdr(BLHdr):
+    DIRTY_BIT_p = 4
+    DIRTY_BIT_m = (0b1 << DIRTY_BIT_p)
+    LAST_HASH_CHAR_p = 0
+    LAST_HASH_CHAR_m = (0xf << LAST_HASH_CHAR_p)
+
+    def len(self):
+        """1B for MAJOR + 1B for MINOR + 1B for PATCH + 1B for NCOMMITS + 3B for 6 hex digits of the hash"""
+        return 7
+
+    def payload_class(self):
+        return BLVersion
+
+    def is_dirty(self):
+        return bool(self.hdr & BLVersionHdr.DIRTY_BIT_m)
+
+    def last_hash(self):
+        return self.hdr & BLVersionHdr.LAST_HASH_CHAR_m
+
+
+class BLVersion():
+    def __init__(self, header, payload):
+        self.major, self.minor, self.patch, self.ncommits, hash_12, hash_34, hash_56 = payload
+        self.header = header
+        self.dirty = self.header.is_dirty()
+        self.hash = f"{hash_12:02x}{hash_34:02x}{hash_56:02x}{self.header.last_hash():0x}"
+
+    def __str__(self):
+        return f"Bootloader v{self.major}.{self.minor}.{self.patch}-{self.ncommits}-g{self.hash}{'-dirty' if self.dirty else ''} is online"  # noqa: E501
+
+
+class BLParser():
+    @classmethod
+    def parse(cls, payload):
+        if not payload:
+            logging.error("No bootloader data is available!")
+            return
+        cursor = 0
+        while cursor < len(payload):
+            blhdr = get_blhdr(payload[cursor])
+            clss = blhdr.payload_class()
+            cursor += 1
+            if len(payload) < cursor + blhdr.len():
+                logging.error(f"Invalid data header of type {type(blhdr).__name__}")
+                return
+            yield clss(blhdr, payload[cursor:cursor + blhdr.len()])
+            cursor += blhdr.len()
+
+
 def crc16_xmodem(data):
     # Credits: https://gist.github.com/oysstu/68072c44c02879a2abf94ef350d1c7c6?permalink_comment_id=3943460#gistcomment-3943460    # noqa: E501
     '''
@@ -190,6 +270,22 @@ def main():
     try:
         # Request flashloader through bootloader (Set to read-only-mode by default)
         bootCtrl.enterFlashloader()
+
+        bus = SMBus(args.i2c_bus)
+        bl_raw_data = []
+        while True:
+            try:
+                # Read bl_data byte per byte
+                bl_raw_data.append(bus.read_byte(BL_I2C_DEV))
+            except IOError:
+                # Bootloader finished sending bl_data
+                break
+
+        bl_data = BLParser.parse(bl_raw_data)
+
+        for d in bl_data:
+            logging.info(d)
+
         bootCtrl.exitRoMode()
         ret = fw_flash(_bin, args.i2c_bus)