fcc-unlock: add support for Lenovo-shipped FM350-GL FCC unlock

data/dispatcher-fcc-unlock/14c3

@@ -0,0 +1,92 @@
+#!/bin/bash
+
+# SPDX-License-Identifier: CC0-1.0
+# 2023 Thilo-Alexander Ginkel <thilo@ginkel.com>
+#
+# Lenovo-shipped Fibocom FM350-GL (14c3:4d75) FCC unlock
+
+if [[ "$FCC_UNLOCK_DEBUG_LOG" == '1' ]]; then
+    exec 3>&1 4>&2
+    trap 'exec 2>&4 1>&3' 0 1 2 3
+    exec 1>>/var/log/mm-fm350-fcc.log 2>&1
+fi
+
+# require program name and at least 2 arguments
+[ $# -lt 2 ] && exit 1
+
+# first argument is DBus path, not needed here
+shift
+
+# second and next arguments are control port names
+for PORT in "$@"; do
+  # match port type in Linux 5.14 and newer
+  grep -q AT "/sys/class/wwan/$PORT/type" 2>/dev/null && {
+    AT_PORT=$PORT
+    break
+  }
+  # match port name in Linux 5.13
+  echo "$PORT" | grep -q AT && {
+    AT_PORT=$PORT
+    break
+  }
+done
+
+# fail if no AT port exposed
+[ -n "$AT_PORT" ] || exit 2
+
+DEVICE=/dev/${AT_PORT}
+
+at_command() {
+    exec 99<>"$DEVICE"
+    echo -e "$1\r" >&99
+    read answer <&99
+    read answer <&99
+    echo "$answer"
+    exec 99>&-
+}
+
+log() {
+    echo "$1"
+}
+
+error() {
+    echo "$1" >&2
+}
+
+VENDOR_ID_HASH="3df8c719"
+
+for i in {1..9}; do
+    log "Requesting challenge from WWAN modem (attempt #${i})"
+    RAW_CHALLENGE=$(at_command "at+gtfcclockgen")
+    CHALLENGE=$(echo "$RAW_CHALLENGE" | grep -o '0x[0-9a-fA-F]\+' | awk '{print $1}')
+
+    if [ -n "$CHALLENGE" ]; then
+        log "Got challenge from modem: $CHALLENGE"
+        HEX_CHALLENGE=$(printf "%08x" "$CHALLENGE")
+        COMBINED_CHALLENGE="${HEX_CHALLENGE}$(printf "%.8s" "${VENDOR_ID_HASH}")"
+        RESPONSE_HASH=$(echo "$COMBINED_CHALLENGE" | xxd -r -p | sha256sum | cut -d ' ' -f 1)
+        TRUNCATED_RESPONSE=$(printf "%.8s" "$RESPONSE_HASH")
+        RESPONSE=$(printf "%d" "0x$TRUNCATED_RESPONSE")
+
+        log "Sending response to WWAN modem: $RESPONSE"
+        UNLOCK_RESPONSE=$(at_command "at+gtfcclockver=$RESPONSE")
+
+        if [[ "$UNLOCK_RESPONSE" == "+GTFCCLOCKVER:"* ]]; then
+            UNLOCK_RESULT=$(echo "$UNLOCK_RESPONSE" | grep -o '[0-9]\+')
+            if [[ "$UNLOCK_RESULT" == "1" ]]; then
+                log "FCC unlock succeeded"
+                exit 0
+            else
+                error "FCC unlock failed. Got result: $UNLOCK_RESULT"
+            fi
+        else
+            error "Unlock failed. Got response: $UNLOCK_RESPONSE"
+        fi
+    else
+        error "Failed to obtain FCC challenge. Got: ${RAW_CHALLENGE}"
+    fi
+
+    sleep 0.5
+done
+
+exit 2

data/dispatcher-fcc-unlock/meson.build

@@ -13,6 +13,7 @@ mm_fccunlockdirpackage = mm_pkglibdir / 'fcc-unlock.d'
 examples = files(
   '105b',
   '1199',
+  '14c3',
   '1eac',
   '2c7c',
 )
@@ -30,6 +31,7 @@ vidpids = {
   '1199:9079': '1199',
   '413c:81a3': '1199',
   '413c:81a8': '1199',
+  '14c3:4d75': '14c3',
   '1eac:1001': '1eac',
   '2c7c:030a': '2c7c',
 }