esp32: Allow RTC slow memory to be reserved for ULP coprocessor

components/esp32/Kconfig

@@ -110,4 +110,28 @@ config NEWLIB_STDOUT_ADDCR
 		is usually done by an added CR character. Enabling this will make the
 		standard output code automatically add a CR character before a LF.
 
+config ULP_COPROC_ENABLED
+    bool "Enable Ultra Low Power (ULP) Coprocessor"
+    default "n"
+    help
+		Set to 'y' if you plan to load a firmware for the coprocessor.
+
+		If this option is enabled, further coprocessor configuration will appear in the Components menu.
+
+config ULP_COPROC_RESERVE_MEM
+	int "RTC slow memory reserved for coprocessor"
+	default 512
+	range 32 8192
+	depends on ULP_COPROC_ENABLED
+	help
+		Bytes of memory to reserve for ULP coprocessor firmware & data.
+
+		Data is reserved at the beginning of RTC slow memory.
+
+# Set CONFIG_ULP_COPROC_RESERVE_MEM to 0 if ULP is disabled
+config ULP_COPROC_RESERVE_MEM
+	int
+	default 0
+	depends on !ULP_COPROC_ENABLED
+
 endmenu

components/esp32/ld/esp32.ld

@@ -43,8 +43,12 @@ MEMORY
    */
   rtc_iram_seg(RWX) :                org = 0x400C0000, len = 0x2000
 
-  /* RTC slow memory (data accessible). Persists over deep sleep. */
-  rtc_slow_seg(RW)  :                org = 0x50000000, len = 0x2000
+  /* RTC slow memory (data accessible). Persists over deep sleep.
+
+     Start of RTC slow memory is reserved for ULP co-processor code + data, if enabled.
+  */
+  rtc_slow_seg(RW)  :                org = 0x50000000 + CONFIG_ULP_COPROC_RESERVE_MEM,
+                                     len = 0x2000 - CONFIG_ULP_COPROC_RESERVE_MEM
 }
 
 /* Heap ends at top of dram0_0_seg */