esp32: Rework board variant support to require mpconfigvariant file.

This commit reworks board variants on the esp32 port.  It's a simple change
that moves the board variant configuration from an "if" statement within
`mpconfigboard.cmake` into separate files for each variant, with the name
of the variant encoded in the filename: `mpconfigvariant_VARIANT.cmake`.

Optionally, the base variant can have its own options in
`mpconfigvariant.cmake` (this is an optional file, but all other variants
of the base must have a corresponding mpconfigvariant file).

There are two benefits to this:
- The build system now gives an error if the variant that you specified
  doesn't exist (because the mpconfigvariant file must exist with the
  variant name you specify).
- No more error-prone if-logic needed in the .cmake files.

The way to build a variant is unchanged, still via:

    $ make BOARD_VARIANT=VARIANT

Signed-off-by: Damien George <damien@micropython.org>

9 files changed, 60 insertions, 66 deletions

diff --git a/ports/esp32/CMakeLists.txt b/ports/esp32/CMakeLists.txt
index 3fe083002..d3927cd48 100644
--- a/ports/esp32/CMakeLists.txt
+++ b/ports/esp32/CMakeLists.txt
@@ -19,6 +19,13 @@ if(NOT EXISTS ${MICROPY_BOARD_DIR}/mpconfigboard.cmake)
     message(FATAL_ERROR "Invalid MICROPY_BOARD specified: ${MICROPY_BOARD}")
 endif()
 
+# If a board variant is specified, check that it exists.
+if(MICROPY_BOARD_VARIANT)
+    if(NOT EXISTS ${MICROPY_BOARD_DIR}/mpconfigvariant_${MICROPY_BOARD_VARIANT}.cmake)
+        message(FATAL_ERROR "Invalid MICROPY_BOARD_VARIANT specified: ${MICROPY_BOARD_VARIANT}")
+    endif()
+endif()
+
 # Define the output sdkconfig so it goes in the build directory.
 set(SDKCONFIG ${CMAKE_BINARY_DIR}/sdkconfig)
 
@@ -35,6 +42,11 @@ endif()
 # - SDKCONFIG_DEFAULTS
 # - IDF_TARGET
 include(${MICROPY_BOARD_DIR}/mpconfigboard.cmake)
+if(NOT MICROPY_BOARD_VARIANT)
+    include(${MICROPY_BOARD_DIR}/mpconfigvariant.cmake OPTIONAL)
+else()
+    include(${MICROPY_BOARD_DIR}/mpconfigvariant_${MICROPY_BOARD_VARIANT}.cmake)
+endif()
 
 # Set the frozen manifest file. Note if MICROPY_FROZEN_MANIFEST is set from the cmake
 # command line, then it will override the default and any manifest set by the board.
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
index a3e8f616b..9d0077a15 100644
--- a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
@@ -3,50 +3,3 @@ set(SDKCONFIG_DEFAULTS
     ${SDKCONFIG_IDF_VERSION_SPECIFIC}
     boards/sdkconfig.ble
 )
-
-if(MICROPY_BOARD_VARIANT STREQUAL "D2WD")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/ESP32_GENERIC/sdkconfig.d2wd
-    )
-
-    list(APPEND MICROPY_DEF_BOARD
-        MICROPY_HW_MCU_NAME="ESP32-D2WD"
-        # Disable some options to reduce firmware size.
-        MICROPY_OPT_COMPUTED_GOTO=0
-        MICROPY_PY_NETWORK_LAN=0
-    )
-endif()
-
-if(MICROPY_BOARD_VARIANT STREQUAL "OTA")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/ESP32_GENERIC/sdkconfig.ota
-    )
-
-    list(APPEND MICROPY_DEF_BOARD
-        MICROPY_HW_BOARD_NAME="Generic ESP32 module with OTA"
-    )
-endif()
-
-if(MICROPY_BOARD_VARIANT STREQUAL "SPIRAM")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/sdkconfig.spiram
-    )
-
-    list(APPEND MICROPY_DEF_BOARD
-        MICROPY_HW_BOARD_NAME="Generic ESP32 module with SPIRAM"
-    )
-endif()
-
-if(MICROPY_BOARD_VARIANT STREQUAL "UNICORE")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/ESP32_GENERIC/sdkconfig.unicore
-    )
-
-    list(APPEND MICROPY_DEF_BOARD
-        MICROPY_HW_MCU_NAME="ESP32-UNICORE"
-    )
-endif()
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_D2WD.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_D2WD.cmake
new file mode 100644
index 000000000..170c214bd
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_D2WD.cmake
@@ -0,0 +1,11 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/ESP32_GENERIC/sdkconfig.d2wd
+)
+
+list(APPEND MICROPY_DEF_BOARD
+    MICROPY_HW_MCU_NAME="ESP32-D2WD"
+    # Disable some options to reduce firmware size.
+    MICROPY_OPT_COMPUTED_GOTO=0
+    MICROPY_PY_NETWORK_LAN=0
+)
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_OTA.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_OTA.cmake
new file mode 100644
index 000000000..7f649c36f
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_OTA.cmake
@@ -0,0 +1,8 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/ESP32_GENERIC/sdkconfig.ota
+)
+
+list(APPEND MICROPY_DEF_BOARD
+    MICROPY_HW_BOARD_NAME="Generic ESP32 module with OTA"
+)
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_SPIRAM.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_SPIRAM.cmake
new file mode 100644
index 000000000..11e9c4eda
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_SPIRAM.cmake
@@ -0,0 +1,8 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/sdkconfig.spiram
+)
+
+list(APPEND MICROPY_DEF_BOARD
+    MICROPY_HW_BOARD_NAME="Generic ESP32 module with SPIRAM"
+)
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_UNICORE.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_UNICORE.cmake
new file mode 100644
index 000000000..beed6eb09
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigvariant_UNICORE.cmake
@@ -0,0 +1,8 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/ESP32_GENERIC/sdkconfig.unicore
+)
+
+list(APPEND MICROPY_DEF_BOARD
+    MICROPY_HW_MCU_NAME="ESP32-UNICORE"
+)
diff --git a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.cmake b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.cmake
index 1f7440353..2bfdad21d 100644
--- a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.cmake
+++ b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.cmake
@@ -8,22 +8,3 @@ set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.spiram_sx
     boards/ESP32_GENERIC_S3/sdkconfig.board
 )
-
-if(MICROPY_BOARD_VARIANT STREQUAL "SPIRAM_OCT")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/sdkconfig.240mhz
-        boards/sdkconfig.spiram_oct
-    )
-
-    list(APPEND MICROPY_DEF_BOARD
-        MICROPY_HW_BOARD_NAME="Generic ESP32S3 module with Octal-SPIRAM"
-    )
-endif()
-
-if(MICROPY_BOARD_VARIANT STREQUAL "FLASH_4M")
-    set(SDKCONFIG_DEFAULTS
-        ${SDKCONFIG_DEFAULTS}
-        boards/ESP32_GENERIC_S3/sdkconfig.flash_4m
-    )
-endif()
diff --git a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_FLASH_4M.cmake b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_FLASH_4M.cmake
new file mode 100644
index 000000000..e832cdb60
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_FLASH_4M.cmake
@@ -0,0 +1,4 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/ESP32_GENERIC_S3/sdkconfig.flash_4m
+)
diff --git a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_SPIRAM_OCT.cmake b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_SPIRAM_OCT.cmake
new file mode 100644
index 000000000..8b2eda272
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigvariant_SPIRAM_OCT.cmake
@@ -0,0 +1,9 @@
+set(SDKCONFIG_DEFAULTS
+    ${SDKCONFIG_DEFAULTS}
+    boards/sdkconfig.240mhz
+    boards/sdkconfig.spiram_oct
+)
+
+list(APPEND MICROPY_DEF_BOARD
+    MICROPY_HW_BOARD_NAME="Generic ESP32S3 module with Octal-SPIRAM"
+)