From 376441f89fa40c3f36166f14c29228f261939f96 Mon Sep 17 00:00:00 2001
From: Dominic Clifton <dominic.clifton@cleanflight.com>
Date: Wed, 28 Aug 2019 14:41:21 +0200
Subject: [PATCH] F3 - Add support for code in CCM RAM.

---
 src/link/stm32_flash.ld      | 13 +++++++++++++
 src/main/drivers/system.c    |  8 ++++++++
 src/main/target/common_pre.h |  8 ++++++++
 3 files changed, 29 insertions(+)

diff --git a/src/link/stm32_flash.ld b/src/link/stm32_flash.ld
index 89d3e97f5..c88e3fc53 100644
--- a/src/link/stm32_flash.ld
+++ b/src/link/stm32_flash.ld
@@ -53,6 +53,19 @@ SECTIONS
     _etext = .;        /* define a global symbols at end of code */
   } >FLASH
 
+  /* Critical program code goes into CCM RAM */
+  /* Copy specific fast-executing code to CCM RAM */ 
+  ccm_code = LOADADDR(.ccm_code); 
+  .ccm_code :
+  {
+    . = ALIGN(4);
+    ccm_code_start = .; 
+    *(.ccm_code)
+    *(.ccm_code*)
+    . = ALIGN(4);
+    ccm_code_end = .; 
+  } >CCM AT >FLASH
+
 
    .ARM.extab   : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
     .ARM : {
diff --git a/src/main/drivers/system.c b/src/main/drivers/system.c
index b36c1f799..0226a878c 100644
--- a/src/main/drivers/system.c
+++ b/src/main/drivers/system.c
@@ -253,6 +253,14 @@ void initialiseMemorySections(void)
     memcpy(&tcm_code_start, &tcm_code, (size_t) (&tcm_code_end - &tcm_code_start));
 #endif
 
+#ifdef USE_CCM_CODE
+    /* Load functions into RAM */
+    extern uint8_t ccm_code_start;
+    extern uint8_t ccm_code_end;
+    extern uint8_t ccm_code;
+    memcpy(&ccm_code_start, &ccm_code, (size_t) (&ccm_code_end - &ccm_code_start));
+#endif
+
 #ifdef USE_FAST_RAM
     /* Load FAST_RAM variable intializers into DTCM RAM */
     extern uint8_t _sfastram_data;
diff --git a/src/main/target/common_pre.h b/src/main/target/common_pre.h
index 5a662b0c8..60923be76 100644
--- a/src/main/target/common_pre.h
+++ b/src/main/target/common_pre.h
@@ -44,6 +44,7 @@
 #define MINIMAL_CLI
 #define USE_DSHOT
 #define USE_GYRO_DATA_ANALYSE
+#define USE_CCM_CODE
 #endif
 
 #ifdef STM32F4
@@ -133,6 +134,7 @@
 #define DEFAULT_AUX_CHANNEL_COUNT       6
 #endif
 
+
 #ifdef USE_ITCM_RAM
 #define FAST_CODE                   __attribute__((section(".tcm_code")))
 #define FAST_CODE_NOINLINE          NOINLINE
@@ -141,6 +143,12 @@
 #define FAST_CODE_NOINLINE
 #endif // USE_ITCM_RAM
 
+#ifdef USE_CCM_CODE
+#define CCM_CODE              __attribute__((section(".ccm_code")))
+#else
+#define CCM_CODE
+#endif
+
 #ifdef USE_FAST_RAM
 #define FAST_RAM_ZERO_INIT             __attribute__ ((section(".fastram_bss"), aligned(4)))
 #define FAST_RAM                    __attribute__ ((section(".fastram_data"), aligned(4)))