esp32p4: add sram_high as second heap region for rev < v3

On ESP32-P4 rev < v3, the 768KB HP L2MEM is split into two
non-contiguous regions: sram_low and sram_high. Previously only
sram_low was used for the heap, wasting 384KB of sram_high.

Export _sram_high_heap_start and _sram_high_heap_end symbols from
the linker script and add sram_high to the heap via kumm_addregion()
in riscv_addregion() when MM_REGIONS > 1.

Signed-off-by: lk <lk@xiaomi.com>
Signed-off-by: likun17 <likun17@xiaomi.com>

Author: Otpvondoiats

arch/risc-v/src/common/espressif/esp_allocateheap.c

@@ -102,6 +102,21 @@ void up_allocate_heap(void **heap_start, size_t *heap_size)
 #if CONFIG_MM_REGIONS > 1
 void riscv_addregion(void)
 {
+#if defined(CONFIG_ESP32P4_SELECTS_REV_LESS_V3)
+  /* ESP32-P4 rev < v3 has non-contiguous SRAM: sram_low + sram_high.
+   * The primary heap is in sram_low. Add sram_high as a second region.
+   */
+
+  extern uint8_t _sram_high_heap_start[];
+  extern uint8_t _sram_high_heap_end[];
+
+  size_t region_size = _sram_high_heap_end - _sram_high_heap_start;
+
+  if (region_size > 0)
+    {
+      kumm_addregion(_sram_high_heap_start, region_size);
+    }
+#endif
 }
 #endif
 

boards/risc-v/esp32p4/common/scripts/esp32p4_sections.ld

@@ -690,6 +690,10 @@ SECTIONS
  _bss_end_high = ABSOLUTE(.);
   } > sram_high
 
+  /* Heap region for sram_high: from end of bss to end of sram_high segment */
+  _sram_high_heap_start = _bss_end_high;
+  _sram_high_heap_end = ORIGIN(sram_high) + LENGTH(sram_high);
+
   /* DWARF 1 */
   .debug 0 : { *(.debug) }
   .line 0 : { *(.line) }