raspberry-pi: fix DTB name mapping for U-Boot

- Gate on rpiVersion instead of architecture; skip for Pi 4+ where
  vendor and upstream DTB names already match
- Fix bcm2835-rpi-zero.dtb: was copied from bcm2708-rpi-b-plus (wrong
  board), now uses bcm2708-rpi-zero
- Drop bcm2711-rpi-4-b -> bcm2838-rpi-4-b copy; nothing uses bcm2838-*

Ref: https://github.com/u-boot/u-boot/blob/master/board/raspberrypi/rpi/rpi.c

Author: JamieMagee

raspberry-pi/common/kernel.nix

@@ -72,42 +72,37 @@ lib.overrideDerivation
       sed -i $buildRoot/include/config/auto.conf -e 's/^CONFIG_LOCALVERSION=.*/CONFIG_LOCALVERSION=""/'
     '';
 
-    # Make copies of the DTBs named after the upstream names so that U-Boot finds them.
-    # This is ugly as heck, but I don't know a better solution so far.
-    postFixup = ''
-      dtbDir=${if stdenv.hostPlatform.isAarch64 then "$out/dtbs/broadcom" else "$out/dtbs"}
-      rm $dtbDir/bcm283*.dtb
-      copyDTB() {
-        cp -v "$dtbDir/$1" "$dtbDir/$2"
-      }
-    ''
-    + lib.optionalString (lib.elem stdenv.hostPlatform.system [ "armv6l-linux" ]) ''
-      copyDTB bcm2708-rpi-zero-w.dtb bcm2835-rpi-zero.dtb
-      copyDTB bcm2708-rpi-zero-w.dtb bcm2835-rpi-zero-w.dtb
-      copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-a.dtb
-      copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b.dtb
-      copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b-rev2.dtb
-      copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-a-plus.dtb
-      copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-b-plus.dtb
-      copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-zero.dtb
-      copyDTB bcm2708-rpi-cm.dtb bcm2835-rpi-cm.dtb
-    ''
-    + lib.optionalString (lib.elem stdenv.hostPlatform.system [ "armv7l-linux" ]) ''
-      copyDTB bcm2709-rpi-2-b.dtb bcm2836-rpi-2-b.dtb
-    ''
-    +
-      lib.optionalString
-        (lib.elem stdenv.hostPlatform.system [
-          "armv7l-linux"
-          "aarch64-linux"
-        ])
-        ''
-          copyDTB bcm2710-rpi-zero-2.dtb bcm2837-rpi-zero-2.dtb
-          copyDTB bcm2710-rpi-zero-2-w.dtb bcm2837-rpi-zero-2-w.dtb
-          copyDTB bcm2710-rpi-3-b.dtb bcm2837-rpi-3-b.dtb
-          copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-a-plus.dtb
-          copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-b-plus.dtb
-          copyDTB bcm2710-rpi-cm3.dtb bcm2837-rpi-cm3.dtb
-          copyDTB bcm2711-rpi-4-b.dtb bcm2838-rpi-4-b.dtb
-        '';
+    # The vendor kernel uses different DTB names (bcm2708/bcm2709/bcm2710) than what
+    # U-Boot expects (bcm2835/bcm2836/bcm2837). Starting with Pi 4, names match.
+    # See: https://github.com/u-boot/u-boot/blob/master/board/raspberrypi/rpi/rpi.c
+    postFixup = lib.optionalString (rpiVersion < 4) (
+      ''
+        dtbDir=${if stdenv.hostPlatform.isAarch64 then "$out/dtbs/broadcom" else "$out/dtbs"}
+        rm $dtbDir/bcm283*.dtb
+        copyDTB() {
+          cp -v "$dtbDir/$1" "$dtbDir/$2"
+        }
+      ''
+      + lib.optionalString (rpiVersion == 1) ''
+        copyDTB bcm2708-rpi-zero.dtb bcm2835-rpi-zero.dtb
+        copyDTB bcm2708-rpi-zero-w.dtb bcm2835-rpi-zero-w.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-a.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b-rev2.dtb
+        copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-a-plus.dtb
+        copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-b-plus.dtb
+        copyDTB bcm2708-rpi-cm.dtb bcm2835-rpi-cm.dtb
+      ''
+      + lib.optionalString (rpiVersion == 2) ''
+        copyDTB bcm2709-rpi-2-b.dtb bcm2836-rpi-2-b.dtb
+      ''
+      + lib.optionalString (rpiVersion == 3) ''
+        copyDTB bcm2710-rpi-zero-2.dtb bcm2837-rpi-zero-2.dtb
+        copyDTB bcm2710-rpi-zero-2-w.dtb bcm2837-rpi-zero-2-w.dtb
+        copyDTB bcm2710-rpi-3-b.dtb bcm2837-rpi-3-b.dtb
+        copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-a-plus.dtb
+        copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-b-plus.dtb
+        copyDTB bcm2710-rpi-cm3.dtb bcm2837-rpi-cm3.dtb
+      ''
+    );
   })