From fb47f094d36a9dd2244d2522079e078a10acafc3 Mon Sep 17 00:00:00 2001
From: Gunar Schorcht <gunar@schorcht.net>
Date: Fri, 10 Jul 2020 08:42:01 +0200
Subject: [PATCH] cpu/esp32: support multiple heaps for newlib

Several unsused DRAM sections are added to the heap.
---
 cpu/esp32/include/cpu_conf.h |  5 +++++
 cpu/esp32/ld/esp32.common.ld | 38 ++++++++++++++++++++++++++++++++----
 cpu/esp_common/syscalls.c    | 21 +++++++++++++++++++-
 3 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/cpu/esp32/include/cpu_conf.h b/cpu/esp32/include/cpu_conf.h
index 89038996d2..6037d499f1 100644
--- a/cpu/esp32/include/cpu_conf.h
+++ b/cpu/esp32/include/cpu_conf.h
@@ -51,6 +51,11 @@ extern "C" {
  */
 #define PRINTF_BUFSIZ 256
 
+/**
+ * @brief   Remaining parts of the various DRAM sections can be used as heap.
+ */
+#define NUM_HEAPS (4)
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/cpu/esp32/ld/esp32.common.ld b/cpu/esp32/ld/esp32.common.ld
index 0b6f4db88a..3fb975dc97 100644
--- a/cpu/esp32/ld/esp32.common.ld
+++ b/cpu/esp32/ld/esp32.common.ld
@@ -97,6 +97,13 @@ SECTIONS
     _iram_start = ABSOLUTE(0);
   } > iram0_0_seg
 
+  /* If Bluetooth is not used, this DRAM section can be used as heap */
+  . = _data_start_btdm; /* 0x3ffae6e0 */
+  . = ALIGN (4);
+  _sheap1 = ABSOLUTE(.);
+  . = 0x3ffb0000;
+  _eheap1 = ABSOLUTE(.);
+
   .iram0.text :
   {
     /* Code marked as running out of IRAM */
@@ -131,8 +138,21 @@ SECTIONS
 
     INCLUDE esp32.spiram.rom-functions-iram.ld
     _iram_text_end = ABSOLUTE(.);
+
+    /* IRAM can't be used as heap since it only allows 32-bit aligned access */
+    /*
+    . = ALIGN (4);
+    _sheap4 = ABSOLUTE(.);
+    */
   } > iram0_0_seg
 
+  /* IRAM can't be used as heap since it only allows 32-bit aligned access */
+  /*
+  . = 0x400a0000;
+  _eheap4 = ABSOLUTE(.);
+  */
+
+  /* Starts at 0x3ffb000 if Bluetooth is not enabled, 0x3ffc0000 otherwise */
   .dram0.data :
   {
     _data_start = ABSOLUTE(.);
@@ -201,13 +221,23 @@ SECTIONS
     _sheap = ABSOLUTE(.);
   } >dram0_0_seg
 
-  /* TODO HEAP handling when BT is used
-     ETS system memory seems to start at 0x3FFE0000 if BT is not used.
-     This is the top of the heap for the app */
-    . = 0x3FFE0000;
+  /* Reserved ROM/ETS data start at 0x3ffe000. */
+  . = 0x3ffe0000;
   _heap_top = ABSOLUTE(.);
   _eheap = ABSOLUTE(.);
 
+  /* Reserved ROM/ETS data region for PRO CPU: 0x3ffe0000 ... 0x3ffe440 */
+  . = 0x3ffe0440;
+  _sheap2 = ABSOLUTE(.);
+  . = 0x3ffe4000;
+  _eheap2 = ABSOLUTE(.);
+
+  /* Reserved ROM/ETS data region for APP CPU: 0x3ffe4000 ... 0x3ffe4350 */
+  . = 0x3ffe4350;
+  _sheap3 = ABSOLUTE(.);
+  . = 0x40000000;
+  _eheap3 = ABSOLUTE(.);
+
   .flash.rodata :
   {
     _rodata_start = ABSOLUTE(.);
diff --git a/cpu/esp_common/syscalls.c b/cpu/esp_common/syscalls.c
index 6674c6e11b..5d520ed0e6 100644
--- a/cpu/esp_common/syscalls.c
+++ b/cpu/esp_common/syscalls.c
@@ -326,10 +326,29 @@ void heap_caps_init(void)
 extern uint8_t  _eheap;     /* end of heap (defined in ld script) */
 extern uint8_t  _sheap;     /* start of heap (defined in ld script) */
 
+extern uint8_t _sheap1;
+extern uint8_t _eheap1;
+
+extern uint8_t _sheap2;
+extern uint8_t _eheap2;
+
+extern uint8_t _sheap3;
+extern uint8_t _eheap3;
+
 unsigned int IRAM_ATTR get_free_heap_size(void)
 {
     struct mallinfo minfo = mallinfo();
-    return &_eheap - &_sheap - minfo.uordblks;
+    unsigned int heap_size = &_eheap - &_sheap;
+#if NUM_HEAPS > 1
+    heap_size += &_eheap1 - &_sheap1;
+#endif
+#if NUM_HEAPS > 2
+    heap_size += &_eheap2 - &_sheap2;
+#endif
+#if NUM_HEAPS > 3
+    heap_size += &_eheap3 - &_sheap3;
+#endif
+    return heap_size - minfo.uordblks;
 }
 
 /* alias for compatibility with espressif/wifi_libs */