Example script to flash the eMMC memory of the STM32MP157C Odyssey SoM

emmc-flash.sh

#! /bin/sh
set -eu

# Config
IMAGES_DIR=/mnt/images # this is the images directory as spit out by buildroot
EMMC_BLK=mmcblk1

# Check if mounted and attempt to mount
if [ ! -d "${IMAGES_DIR}" ] ; then
    echo "warn: ${IMAGES_DIR} not found, attempting to mount /dev/sda1 ..."
    mount /dev/sda1 /mnt
fi

# Check required elements
echo "=> Checking if required elements are found ..."
if [ ! -f "${IMAGES_DIR}/u-boot-spl.stm32" ] ; then
    echo "error: missing '${IMAGES_DIR}/u-boot-spl.stm32'"
    exit 1
fi

if [ ! -f "${IMAGES_DIR}/sdcard.img" ] ; then
    echo "error: missing '${IMAGES_DIR}/sdcard.img'"
    exit 1
fi

if [ ! -e "/dev/${EMMC_BLK}boot0" ] ; then
    echo "error: missing '/dev/${EMMC_BLK}boot0'"
    exit 1
fi

if [ ! -e "/dev/${EMMC_BLK}boot1" ] ; then
    echo "error: missing '/dev/${EMMC_BLK}boot1'"
    exit 1
fi

if [ ! -e "/dev/${EMMC_BLK}" ] ; then
    echo "error: missing '/dev/${EMMC_BLK}'"
    exit 1
fi

if grep -q ${EMMC_BLK} /proc/cmdline ; then
    echo "error: booted from ${EMMC_BLK}, cannot flash it"
    exit 1
fi

# Mark eMMC boot partitions as writable
echo "=> Making boot partition writable ..."
echo 0 > /sys/block/${EMMC_BLK}boot0/force_ro 

# Write partition data
echo "=> Write boot partition ..."
dd if=${IMAGES_DIR}/u-boot-spl.stm32  of=/dev/${EMMC_BLK}boot0
echo "=> Write user partition ..."
dd if=${IMAGES_DIR}/sdcard.img  of=/dev/${EMMC_BLK}

echo "=> Syncing ..."
sync