import i2c_flash.py for flashing Mule-ATtiny FW over I2C

This is an import from
https://gitlab.lan/som/mule-attiny/-/tree/4d0bd1eb6e739c82b82443776cd2a612d2bf2d1a/bootloader/utils/scripts/
with a directory rename to `i2c-flash`.

Relates-to: EHSW-1799
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>

3 files changed, 195 insertions, 0 deletions

diff --git a/mule-attiny/i2c-flash/.flake8 b/mule-attiny/i2c-flash/.flake8
new file mode 100644
index 0000000..6deafc2
--- /dev/null
+++ b/mule-attiny/i2c-flash/.flake8
@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 120
diff --git a/mule-attiny/i2c-flash/i2c_flash.py b/mule-attiny/i2c-flash/i2c_flash.py
new file mode 100755
index 0000000..185ea2e
--- /dev/null
+++ b/mule-attiny/i2c-flash/i2c_flash.py
@@ -0,0 +1,191 @@
+#! /usr/bin/env python3
+
+# ATtiny816 I2C-Flashing script
+# date: 15.05.2023
+
+from smbus2 import SMBus, i2c_msg
+from os import system
+import sys
+import gpiod
+from time import sleep
+from argparse import ArgumentParser
+import pathlib
+import logging
+
+# Bootloader I2C slave address
+BL_I2C_DEV = 0x6f   # Reuse isl1208 address
+
+# Error codes
+FLASH_OK = 0
+FLASH_FAIL = 1
+INVALID_BIN = 2
+
+
+def log_flash_error(msg, pos, bin_len):
+    logging.info(f"Flashing at {pos}/{bin_len} B ...")
+    logging.error(msg)
+
+
+def load_bin(firmware_path):
+    with open(firmware_path, "rb") as fd:
+        return fd.read()
+
+
+class BootModeController:
+
+    def __init__(self, bootReqGpioChip, bootReqGpio, updiResetGpioChip, updiResetGpio):
+        chip = gpiod.chip(bootReqGpioChip)
+        self.__bootReq = chip.get_line(bootReqGpio)
+
+        self.__updiResetGpioChip = updiResetGpioChip
+        self.__updiResetGpio = updiResetGpio
+        self.__flashMode = False
+
+    def enterFlashloader(self):
+        config = gpiod.line_request()
+        config.consumer = "bootPin"
+        config.request_type = gpiod.line_request.DIRECTION_OUTPUT
+
+        self.__bootReq.request(config)
+        self.__bootReq.set_value(1)
+        self.__updi_reset()
+
+        # Wait until ATtiny starts-up. Startup time (Power-ON <--dt--> Code-Exec) is fused to 64 ms (fuse 0x6).
+        sleep(0.1)
+
+        self.__flashMode = True
+
+    def exitFlashloader(self):
+        if self.__bootReq.is_requested():
+            self.__bootReq.set_value(0)
+            self.__bootReq.release()
+
+        if (self.__flashMode):  # Don't leave ATtiny in flashloader mode when error occurs
+            self.__updi_reset()
+
+    def __updi_reset(self):
+        # Issue the reset command
+        # Give this executable the highest scheduling priority (-20) To avoid extra intra-packet sampling delays.
+        ret = system(f"nice --20 updi_reset {self.__updiResetGpioChip} {self.__updiResetGpio}")
+
+        if(ret != 0):
+            raise Exception("UPDI Reset command failed!")
+
+
+def crc16_xmodem(data):
+    # Credits: https://gist.github.com/oysstu/68072c44c02879a2abf94ef350d1c7c6?permalink_comment_id=3943460#gistcomment-3943460    # noqa: E501
+    '''
+    CRC-16 (CCITT) implemented with a precomputed lookup table
+    '''
+    table = [
+        0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108, 0x9129, 0xA14A,
+        0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF, 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294,
+        0x72F7, 0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE, 0x2462,
+        0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509,
+        0xE5EE, 0xF5CF, 0xC5AC, 0xD58D, 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695,
+        0x46B4, 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC, 0x48C4, 0x58E5,
+        0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948,
+        0x9969, 0xA90A, 0xB92B, 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
+        0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A, 0x6CA6, 0x7C87, 0x4CE4,
+        0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B,
+        0x8D68, 0x9D49, 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F,
+        0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78, 0x9188, 0x81A9, 0xB1CA, 0xA1EB,
+        0xD10C, 0xC12D, 0xF14E, 0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046,
+        0x6067, 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E, 0x02B1, 0x1290,
+        0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256, 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E,
+        0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+        0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691,
+        0x16B0, 0x6657, 0x7676, 0x4615, 0x5634, 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9,
+        0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3, 0xCB7D,
+        0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37, 0x7A16,
+        0x0AF1, 0x1AD0, 0x2AB3, 0x3A92, 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8,
+        0x8DC9, 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1, 0xEF1F, 0xFF3E,
+        0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93,
+        0x3EB2, 0x0ED1, 0x1EF0
+    ]
+
+    crc = 0x0000
+    for byte in data:
+        crc = (crc << 8) ^ table[(crc >> 8) ^ byte]
+        crc &= 0xFFFF   # important, crc must stay 16bits all the way through
+    return crc
+
+
+def is_valid_bin(_bin):
+    # Check if firmware binary has a valid xmodem CRC at the last two bytes
+    if (crc16_xmodem(_bin) != 0):
+        logging.error("Invalid firmware CRC! Maybe you picked a wrong file?")
+        return False
+
+    return True
+
+
+def fw_flash(_bin, i2cBus):
+    logging.info("Start flashing ...")
+
+    bus = SMBus(i2cBus)
+
+    for idx, data in enumerate(_bin):
+        wr = i2c_msg.write(BL_I2C_DEV, [data])
+        rd = i2c_msg.read(BL_I2C_DEV, 1)
+
+        try:
+            bus.i2c_rdwr(wr, rd)    # Combined write-read op
+        except Exception as err:
+            # Reset device
+            log_flash_error(f"No i2c device found at {i2cBus}-{BL_I2C_DEV:04x}. Bootloader or Reset missing", idx, len(_bin))    # noqa: E501
+            system(f'i2cdetect -a -y {i2cBus}')
+            raise err
+
+        if list(rd)[0] != data:
+            log_flash_error(f"Expected {hex(data)} but received {hex(list(rd)[0])}", idx, len(_bin))
+            return FLASH_FAIL
+
+    logging.info("Firmware flashing completed")
+    return FLASH_OK
+
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.INFO, format='[%(levelname)s] %(message)s')
+
+    parser = ArgumentParser(
+            prog='i2c_flash.py',
+            description='Script to flash mule-ATtiny firmware through I2C-Flashloader',
+            epilog='')
+
+    parser.add_argument('-f', '--firmware', required=True, help="Path to the firmware binary file")
+    parser.add_argument('-c', '--boot_req_gpiochip', type=int, required=True, help="Boot request gpiochip index number (e.g. 0 if /dev/gpiochip0)/")   # noqa: E501
+    parser.add_argument('-g', '--boot_req_gpio', type=int, required=True, help="Boot request GPIO index in the gpiochip (e.g. if GPIO3_A5, boot_req_gpiochip is 3 and boot_req_gpio is 5")  # noqa: E501
+    parser.add_argument('-b', '--i2c_bus', type=int, required=True, help="I2C bus index (e.g. 2 if /dev/i2c-2) connected to ATtiny")    # noqa: E501
+    parser.add_argument('-rc', '--updi_reset_gpiochip', type=int, required=True, help="Updi_reset gpiochip index number (e.g. 0 if /dev/gpiochip0)/")   # noqa: E501
+    parser.add_argument('-rg', '--updi_reset_gpio', type=int, required=True, help="Updi_reset GPIO index in the gpiochip (e.g. if GPIO3_A4, boot_req_gpiochip is 3 and boot_req_gpio is 4")  # noqa: E501
+
+    # Get binarry path from cli
+    args = parser.parse_args()
+
+    # Open binary file and copy data to "_bin" bytearray
+    _bin = load_bin(args.firmware)
+
+    if not is_valid_bin(_bin):
+        sys.exit(INVALID_BIN)
+
+    # Make sure kernel doesn't access the isl1208 address while flashing
+    if pathlib.Path(f"/sys/bus/i2c/drivers/rtc-isl1208/{args.i2c_bus}-{BL_I2C_DEV:04x}").exists():
+        system(f"echo {args.i2c_bus}-{BL_I2C_DEV:04x} > /sys/bus/i2c/drivers/rtc-isl1208/unbind")
+
+    bootCtrl = BootModeController(
+        args.boot_req_gpiochip, args.boot_req_gpio, args.updi_reset_gpiochip, args.updi_reset_gpio
+    )
+
+    try:
+        # Request flashloader through bootloader
+        bootCtrl.enterFlashloader()
+        ret = fw_flash(_bin, args.i2c_bus)
+
+    except Exception as err:
+        raise err
+
+    finally:
+        bootCtrl.exitFlashloader()
+
+    sys.exit(ret)
diff --git a/mule-attiny/i2c-flash/requirements.txt b/mule-attiny/i2c-flash/requirements.txt
new file mode 100644
index 0000000..553b331
--- /dev/null
+++ b/mule-attiny/i2c-flash/requirements.txt
@@ -0,0 +1,2 @@
+gpiod==1.5.4
+smbus2==0.4.2