esp32: Workaround IDF issue placing ISR ringbuf functions in IRAM.

This workaround makes sure that all ringbuf functions that may be called
from an ISR are placed in IRAM.  See
https://github.com/espressif/esp-idf/issues/13378

Note that this means that all esp32-og builds get non-ISR ringbuf functions
placed in flash now, whereas previously it was just the spiram variant.
This might be a good thing (e.g. free up some IRAM for native/viper).

Fixes issue #14005.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

ports/esp32/boards/sdkconfig.spiram

@@ -13,6 +13,6 @@ CONFIG_SPIRAM_MALLOC_ALWAYSINTERNAL=8192
 # to PSRAM bug workarounds.  Apply some options to reduce the firmware size.
 CONFIG_COMPILER_OPTIMIZATION_SIZE=y
 CONFIG_COMPILER_OPTIMIZATION_CHECKS_SILENT=y
-CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y
+# CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y # Workaround required: see main_esp32/linker.lf
 CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH=y
 CONFIG_FREERTOS_PLACE_SNAPSHOT_FUNS_INTO_FLASH=y

ports/esp32/esp32_common.cmake

@@ -151,6 +151,8 @@ idf_component_register(
         ${MICROPY_PORT_DIR}
         ${MICROPY_BOARD_DIR}
         ${CMAKE_BINARY_DIR}
+    LDFRAGMENTS
+        linker.lf
     REQUIRES
         ${IDF_COMPONENTS}
 )

ports/esp32/main_esp32/linker.lf

@@ -0,0 +1,39 @@
+# This fixes components/esp_ringbuf/linker.lf to allow us to put non-ISR ringbuf functions in flash.
+
+# Requires that both RINGBUF_PLACE_FUNCTIONS_INTO_FLASH and RINGBUF_PLACE_ISR_FUNCTIONS_INTO_FLASH
+# are set to "n" (which is the default), otherwise this would result in duplicate section config
+# when resolving the linker fragments.
+
+# The effect of this file is to leave the ISR functions in RAM (which we require), but apply a fixed
+# version of RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y (leaving out prvGetFreeSize and prvGetCurMaxSizeByteBuf)
+# See https://github.com/espressif/esp-idf/issues/13378
+
+[mapping:esp_ringbuf_fix]
+archive: libesp_ringbuf.a
+entries:
+    # This is exactly the list of functions from RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y,
+    # but with prvGetFreeSize and prvGetCurMaxSizeByteBuf removed.
+    ringbuf: prvGetCurMaxSizeNoSplit (default)
+    ringbuf: prvGetCurMaxSizeAllowSplit (default)
+    ringbuf: prvInitializeNewRingbuffer (default)
+    ringbuf: prvReceiveGeneric (default)
+    ringbuf: vRingbufferDelete (default)
+    ringbuf: vRingbufferGetInfo (default)
+    ringbuf: vRingbufferReturnItem (default)
+    ringbuf: xRingbufferAddToQueueSetRead (default)
+    ringbuf: xRingbufferCanRead (default)
+    ringbuf: xRingbufferCreate (default)
+    ringbuf: xRingbufferCreateStatic (default)
+    ringbuf: xRingbufferCreateNoSplit (default)
+    ringbuf: xRingbufferReceive (default)
+    ringbuf: xRingbufferReceiveSplit (default)
+    ringbuf: xRingbufferReceiveUpTo (default)
+    ringbuf: xRingbufferRemoveFromQueueSetRead (default)
+    ringbuf: xRingbufferSend (default)
+    ringbuf: xRingbufferSendAcquire (default)
+    ringbuf: xRingbufferSendComplete (default)
+    ringbuf: xRingbufferPrintInfo (default)
+    ringbuf: xRingbufferGetMaxItemSize (default)
+    ringbuf: xRingbufferGetCurFreeSize (default)
+
+    # Everything else will have the default rule already applied (i.e. noflash_text).

ports/esp32/main_esp32c3/linker.lf

@@ -0,0 +1 @@
+# Empty linker fragment (no workaround required for C3, see main_esp32/linker.lf).

ports/esp32/main_esp32s2/linker.lf

@@ -0,0 +1 @@
+# Empty linker fragment (no workaround required for S2, see main_esp32/linker.lf).

ports/esp32/main_esp32s3/linker.lf

@@ -0,0 +1 @@
+# Empty linker fragment (no workaround required for S3, see main_esp32/linker.lf).