rpi-eeprom-config/update: Exit cleanly when not run on rpi4

Some users might forcibly install this on a board that isn't an rpi4.
Exit early, and explain why the program can't be run.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

rpi-eeprom-config

@@ -32,6 +32,15 @@ FILE_HDR_LEN = 20
 FILENAME_LEN = 12
 TEMP_DIR = None
 
+def rpi4():
+    compatible_path = "/sys/firmware/devicetree/base/compatible"
+    if os.path.exists(compatible_path):
+        with open(compatible_path, "rb") as f:
+            compatible = f.read().decode('utf-8')
+            if "bcm2711" in compatible:
+                return True
+    return False
+
 def exit_handler():
     """
     Delete any temporary files.
@@ -327,10 +336,12 @@ images.
     parser.add_argument('eeprom', nargs='?', help='Name of EEPROM file to use as input')
     args = parser.parse_args()
 
-
     if (args.edit or args.apply is not None) and os.getuid() != 0:
         exit_error("--edit/--apply must be run as root")
 
+    if (args.edit or args.apply is not None) and not rpi4():
+        exit_error("--edit/--apply must run on a Raspberry Pi 4")
+
     if args.edit:
         edit_config(args.eeprom)
     elif args.apply is not None:

rpi-eeprom-update

@@ -346,6 +346,7 @@ checkDependencies() {
       echo "BCM2711 detected"
    else
       # Not a BCM2711, no EEPROMs to update.
+      echo "This tool only works with a Raspberry Pi 4"
       exit ${EXIT_SUCCESS}
    fi