arch/xtensa/esp32: Add the RTC Slow memory as a separate heap.

This memory region can be accessed by both I & D buses, so the heap can
be used for data storage and code execution.

Signed-off-by: Abdelatif Guettouche <abdelatif.guettouche@espressif.com>

arch/xtensa/src/esp32/Kconfig

@@ -231,6 +231,10 @@ config ESP32_RUN_IRAM
 		This loads all of NuttX inside IRAM.  Used to test somewhat small
 		images that can fit entirely in IRAM.
 
+config ESP32_RTC_HEAP
+	bool "Use the RTC memory as a separate heap"
+	default n
+
 menu "ESP32 Peripheral Selection"
 
 config ESP32_UART

arch/xtensa/src/esp32/Make.defs

@@ -97,6 +97,10 @@ ifeq ($(CONFIG_XTENSA_IMEM_USE_SEPARATE_HEAP),y)
 CHIP_CSRCS += esp32_imm.c
 endif
 
+ifeq ($(CONFIG_ESP32_RTC_HEAP),y)
+CHIP_CSRCS += esp32_rtcheap.c
+endif
+
 ifeq ($(CONFIG_ESP32_I2C),y)
 CHIP_CSRCS += esp32_i2c.c
 endif

arch/xtensa/src/esp32/esp32_rtcheap.c

@@ -0,0 +1,201 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32/esp32_rtcheap.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/fs/procfs.h>
+#include <nuttx/mm/mm.h>
+#include <malloc.h>
+
+#include "esp32_rtcheap.h"
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct mm_heap_s g_rtcheap;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: esp32_rtcheap_initialize
+ *
+ * Description:
+ *   Initialize the RTC heap.
+ *
+ ****************************************************************************/
+
+void esp32_rtcheap_initialize(void)
+{
+  void  *start;
+  size_t size;
+
+  /* These values come from the linker scripts. Check boards/xtensa/esp32. */
+
+  extern uint8_t *_srtcheap;
+  extern uint8_t *_ertcheap;
+
+  start = (void *)&_srtcheap;
+  size  = (size_t)((uintptr_t)&_ertcheap - (uintptr_t)&_srtcheap);
+  mm_initialize(&g_rtcheap, start, size);
+
+#if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MEMINFO)
+  static struct procfs_meminfo_entry_s g_rtc_procfs;
+
+  g_rtc_procfs.name = "rtcheap";
+  g_rtc_procfs.mallinfo = (void *)mm_mallinfo;
+  g_rtc_procfs.user_data = &g_rtcheap;
+  procfs_register_meminfo(&g_rtc_procfs);
+#endif
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_malloc
+ *
+ * Description:
+ *   Allocate memory from the RTC heap.
+ *
+ * Parameters:
+ *   size - Size (in bytes) of the memory region to be allocated.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_malloc(size_t size)
+{
+  return mm_malloc(&g_rtcheap, size);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_calloc
+ *
+ * Description:
+ *   Calculates the size of the allocation and allocate memory from
+ *   the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_calloc(size_t n, size_t elem_size)
+{
+  return mm_calloc(&g_rtcheap, n, elem_size);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_realloc
+ *
+ * Description:
+ *   Reallocate memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_realloc(void *ptr, size_t size)
+{
+  return mm_realloc(&g_rtcheap, ptr, size);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_zalloc
+ *
+ * Description:
+ *   Allocate and zero memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_zalloc(size_t size)
+{
+  return mm_zalloc(&g_rtcheap, size);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_free
+ *
+ * Description:
+ *   Free memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void esp32_rtcheap_free(void *mem)
+{
+  mm_free(&g_rtcheap, mem);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_memalign
+ *
+ * Description:
+ *   memalign requests more than enough space from malloc, finds a region
+ *   within that chunk that meets the alignment request and then frees any
+ *   leading or trailing space.
+ *
+ *   The alignment argument must be a power of two (not checked).  8-byte
+ *   alignment is guaranteed by normal malloc calls.
+ *
+ * Parameters:
+ *   alignment - Requested alignment.
+ *   size - Size (in bytes) of the memory region to be allocated.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_memalign(size_t alignment, size_t size)
+{
+  return mm_memalign(&g_rtcheap, alignment, size);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_heapmember
+ *
+ * Description:
+ *   Check if an address lies in the RTC heap.
+ *
+ * Parameters:
+ *   mem - The address to check.
+ *
+ * Return Value:
+ *   True if the address is a member of the RTC heap.  False if not.
+ *
+ ****************************************************************************/
+
+bool esp32_rtcheap_heapmember(void *mem)
+{
+  return mm_heapmember(&g_rtcheap, mem);
+}
+
+/****************************************************************************
+ * Name: esp32_rtcheap_mallinfo
+ *
+ * Description:
+ *   mallinfo returns a copy of updated current heap information for the
+ *   user heap.
+ *
+ * Parameters:
+ *   info - Where memory information will be copied.
+ *
+ ****************************************************************************/
+
+int esp32_rtcheap_mallinfo(struct mallinfo *info)
+{
+  return mm_mallinfo(&g_rtcheap, info);
+}

arch/xtensa/src/esp32/esp32_rtcheap.h

@@ -0,0 +1,149 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32/esp32_rtcheap.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_XTENSA_SRC_ESP32_ESP32_RTCHEAP_H
+#define __ARCH_XTENSA_SRC_ESP32_ESP32_RTCHEAP_H
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+struct mallinfo; /* Forward reference, see malloc.h */
+
+/****************************************************************************
+ * Name: esp32_rtcheap_initialize
+ *
+ * Description:
+ *   Initialize the RTC heap.
+ *
+ ****************************************************************************/
+
+void esp32_rtcheap_initialize(void);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_malloc
+ *
+ * Description:
+ *   Allocate memory from the RTC heap.
+ *
+ * Parameters:
+ *   size - Size (in bytes) of the memory region to be allocated.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_malloc(size_t size);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_calloc
+ *
+ * Description:
+ *   Calculates the size of the allocation and allocate memory from
+ *   the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_calloc(size_t n, size_t elem_size);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_realloc
+ *
+ * Description:
+ *   Reallocate memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_realloc(void *ptr, size_t size);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_zalloc
+ *
+ * Description:
+ *   Allocate and zero memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_zalloc(size_t size);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_free
+ *
+ * Description:
+ *   Free memory from the RTC heap.
+ *
+ ****************************************************************************/
+
+void esp32_rtcheap_free(void *mem);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_memalign
+ *
+ * Description:
+ *   memalign requests more than enough space from malloc, finds a region
+ *   within that chunk that meets the alignment request and then frees any
+ *   leading or trailing space.
+ *
+ *   The alignment argument must be a power of two (not checked). 8-byte
+ *   alignment is guaranteed by normal malloc calls.
+ *
+ ****************************************************************************/
+
+void *esp32_rtcheap_memalign(size_t alignment, size_t size);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_heapmember
+ *
+ * Description:
+ *   Check if an address lies in the RTC heap.
+ *
+ * Parameters:
+ *   mem - The address to check
+ *
+ * Return Value:
+ *   True if the address is a member of the RTC heap. False if not.
+ *
+ ****************************************************************************/
+
+bool esp32_rtcheap_heapmember(void *mem);
+
+/****************************************************************************
+ * Name: esp32_rtcheap_mallinfo
+ *
+ * Description:
+ *   mallinfo returns a copy of updated current heap information for the
+ *   user heap.
+ *
+ ****************************************************************************/
+
+int esp32_rtcheap_mallinfo(struct mallinfo *info);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ARCH_XTENSA_SRC_ESP32_ESP32_RTCHEAP_H */

boards/xtensa/esp32/esp32-devkitc/scripts/esp32.template.ld

@@ -81,3 +81,7 @@ _eheap = 0x40000000 - CONFIG_ESP32_TRACEMEM_RESERVE_DRAM;
 /* Text heap ends at top of dram0_0_seg */
 
 _etextheap = 0x400a0000;
+
+/* Mark the end of the RTC heap (top of the RTC region) */
+
+_ertcheap = 0x50001fff;

boards/xtensa/esp32/esp32-devkitc/scripts/esp32_flash.ld

@@ -215,5 +215,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }

boards/xtensa/esp32/esp32-devkitc/scripts/esp32_iram.ld

@@ -192,5 +192,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }

boards/xtensa/esp32/esp32-ethernet-kit/scripts/esp32.template.ld

@@ -81,3 +81,7 @@ _eheap = 0x40000000 - CONFIG_ESP32_TRACEMEM_RESERVE_DRAM;
 /* Text heap ends at top of dram0_0_seg */
 
 _etextheap = 0x400a0000;
+
+/* Mark the end of the RTC heap (top of the RTC region) */
+
+_ertcheap = 0x50001fff;

boards/xtensa/esp32/esp32-ethernet-kit/scripts/esp32_flash.ld

@@ -217,5 +217,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }

boards/xtensa/esp32/esp32-ethernet-kit/scripts/esp32_iram.ld

@@ -192,5 +192,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }

boards/xtensa/esp32/esp32-wrover-kit/scripts/esp32.template.ld

@@ -81,3 +81,7 @@ _eheap = 0x40000000 - CONFIG_ESP32_TRACEMEM_RESERVE_DRAM;
 /* Text heap ends at top of dram0_0_seg */
 
 _etextheap = 0x400a0000;
+
+/* Mark the end of the RTC heap (top of the RTC region) */
+
+_ertcheap = 0x50001fff;

boards/xtensa/esp32/esp32-wrover-kit/scripts/esp32_flash.ld

@@ -217,5 +217,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }

boards/xtensa/esp32/esp32-wrover-kit/scripts/esp32_iram.ld

@@ -192,5 +192,10 @@ SECTIONS
   {
     *(.rtc.data)
     *(.rtc.rodata)
+
+   /* Whatever is left from the RTC memory is used as a special heap. */
+
+    . = ALIGN (4);
+    _srtcheap = ABSOLUTE(.);
   } > rtc_slow_seg
 }