Keymap directory support.

CMakeLists.txt

@@ -4,6 +4,8 @@ cmake_minimum_required(VERSION 3.13.1)
 list(APPEND BOARD_ROOT ${CMAKE_SOURCE_DIR})
 list(APPEND DTS_ROOT ${CMAKE_SOURCE_DIR})
 
+include(cmake/keymap.cmake)
+
 find_package(Zephyr)
 project(zmk)
 

README.md

@@ -6,7 +6,8 @@ with a less restritive license and better BLE support, built on top of the [Zeph
 ## TODO
 
 - Debouncing in the kscan driver itself? Only some GPIO drivers in Zephyr support it "natively"
-- Better DTS overlay setup for _keymaps_. Current use of SHIELDs works, but perhaps would be better with something more integrated.
+- Document boards/shields/keymaps usage.
+- Custom keymap code via `zephyr_library()`>
 - Move most Kconfig setings to the board/keymap defconfigs and out of the toplevel `prj.conf` file.
 - Merge the Kscan GPIO driver upstream, or integrate it locally, to avoid use of Zephyr branch.
 - BLE SC by typing in the # prompted on the host.

boards/shields/petejohanson_handwire/keymaps/petejohanson/keymap.overlay

@@ -0,0 +1,35 @@
+#include <dt-bindings/zmk/keys.h>
+
+/ {
+	chosen {
+		zmk,keymap = &keymap0;
+	};
+	keymap0: keymap {
+		compatible = "zmk,keymap";
+		label ="Default keymap";
+		layers = <&default &lower &raise>;
+	};
+
+	layers {
+		compatible = "zmk,layers";
+
+		default: layer_0 {
+			label = "Default";
+			keys =
+	<
+	KC_A KC_B
+	KC_C ZC_CSTM(1)
+	>;
+		};
+
+		lower: layer_1 {
+			label = "Lower";
+			keys = <KC_D KC_C KC_B KC_A>;
+		};
+
+		raise: layer_2 {
+			label = "Raise";
+			keys = <KC_C KC_D KC_A KC_B>;
+		};
+	};
+};

boards/shields/petejohanson_handwire/petejohanson_handwire.overlay

@@ -1,41 +1,9 @@
-#include <dt-bindings/zmk/keys.h>
 
 / {
 	chosen {
-		zmk,keymap = &keymap0;
 		zmk,kscan = &kscan0;
 	};
 
-	layers {
-		compatible = "zmk,layers";
-
-		default: layer_0 {
-			label = "Default";
-			keys =
-	<
-	KC_A KC_B
-	KC_C ZC_CSTM(1)
-	>;
-		};
-
-		lower: layer_1 {
-			label = "Lower";
-			keys = <KC_D KC_C KC_B KC_A>;
-		};
-
-		raise: layer_2 {
-			label = "Raise";
-			keys = <KC_C KC_D KC_A KC_B>;
-		};
-	};
-
-	keymap0: keymap {
-		compatible = "zmk,keymap";
-
-		label ="Default keymap";
-		layers = <&default &lower &raise>;
-	};
-
 	kscan0: kscan {
 		compatible = "gpio-kscan";
 		label = "KSCAN";

cmake/keymap.cmake

@@ -0,0 +1,91 @@
+
+get_property(cached_keymap_value CACHE KEYMAP PROPERTY VALUE)
+
+# There are actually 4 sources, the three user input sources, and the
+# previously used value (CACHED_KEYMAP). The previously used value has
+# precedence, and if we detect that the user is trying to change the
+# value we give him a warning about needing to clean the build
+# directory to be able to change keymaps.
+
+set(keymap_cli_argument ${cached_keymap_value}) # Either new or old
+if(keymap_cli_argument STREQUAL CACHED_KEYMAP)
+	# We already have a CACHED_KEYMAP so there is no new input on the CLI
+  unset(keymap_cli_argument)
+endif()
+
+set(keymap_app_cmake_lists ${KEYMAP})
+if(cached_keymap_value STREQUAL KEYMAP)
+	# The app build scripts did not set a default, The KEYMAP we are
+  # reading is the cached value from the CLI
+  unset(keymap_app_cmake_lists)
+endif()
+
+if(CACHED_KEYMAP)
+  # Warn the user if it looks like he is trying to change the keymap
+  # without cleaning first
+  if(keymap_cli_argument)
+	  if(NOT (CACHED_KEYMAP STREQUAL keymap_cli_argument))
+      message(WARNING "The build directory must be cleaned pristinely when changing keymaps")
+      # TODO: Support changing keymaps without requiring a clean build
+    endif()
+  endif()
+
+  set(KEYMAP ${CACHED_KEYMAP})
+elseif(keymap_cli_argument)
+	set(KEYMAP ${keymap_cli_argument})
+
+elseif(DEFINED ENV{KEYMAP})
+	set(KEYMAP $ENV{KEYMAP})
+
+elseif(keymap_app_cmake_lists)
+	set(KEYMAP ${keymap_app_cmake_lists})
+
+else()
+	set(KEYMAP default)
+	message(STATUS "KEYMAP defaulted to 'default'")
+endif()
+
+message(STATUS "Keymap: ${KEYMAP}")
+
+# Store the selected keymap in the cache
+set(CACHED_KEYMAP ${KEYMAP} CACHE STRING "Selected keymap")
+
+set(ZMK_APP_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+
+list(APPEND KEYMAP_DIRS ${ZMK_APP_DIR}/keymaps)
+
+foreach(root ${BOARD_ROOT})
+	find_path(BOARD_DIR
+	    NAMES ${BOARD}_defconfig
+	    PATHS ${root}/boards/*/*
+	    NO_DEFAULT_PATH
+	    )
+    	if(BOARD_DIR)
+		list(APPEND KEYMAP_DIRS ${BOARD_DIR}/keymaps)
+	endif()
+
+	if(DEFINED SHIELD)
+		find_path(shields_refs_list
+		    NAMES ${SHIELD}.overlay
+		    PATHS ${root}/boards/shields/*
+		    NO_DEFAULT_PATH
+		    )
+		foreach(shield_path ${shields_refs_list})
+			list(APPEND KEYMAP_DIRS ${shield_path}/keymaps)
+		endforeach()
+	endif()
+endforeach()
+
+foreach(keymap_root ${KEYMAP_DIRS})
+	find_path(KEYMAP_DIR
+		NAMES ${KEYMAP}
+		PATHS ${keymap_root}/*/*
+		NO_DEFAULT_PATH
+	)
+
+	if (KEYMAP_DIR)
+		message(STATUS "Using keymap directory: ${KEYMAP_DIR}/${KEYMAP}/")
+		set(DTC_OVERLAY_FILE ${KEYMAP_DIR}/${KEYMAP}/keymap.overlay)
+		break()
+	endif()
+endforeach()