HAL_ChibiOS: switched to using DTCM memory for DMA

this uses SRAM1 and SRAM2 for main memory, which enables the use of the
data cache for faster operation, and using DTCM for all DMA operations.

libraries/AP_HAL_ChibiOS/Util.cpp

@@ -37,6 +37,7 @@ using namespace ChibiOS;
 extern "C" {
     size_t mem_available(void);
     void *malloc_ccm(size_t size);
+    void *malloc_dtcm(size_t size);
 };
 
 /**
@@ -54,6 +55,11 @@ uint32_t Util::available_memory(void)
 
 void* Util::malloc_type(size_t size, AP_HAL::Util::Memory_Type mem_type)
 {
+#if defined(DTCM_RAM_SIZE) && defined(DTCM_BASE_ADDRESS)
+    if (mem_type == AP_HAL::Util::MEM_DMA_SAFE) {
+        return malloc_dtcm(size);
+    }
+#endif
     if (mem_type == AP_HAL::Util::MEM_FAST) {
         return try_alloc_from_ccm_ram(size);
     } else {

libraries/AP_HAL_ChibiOS/Util.h

@@ -21,10 +21,13 @@
 #include "Semaphores.h"
 #include "ToneAlarm.h"
 
+#if defined(STM32F7) && STM32_DMA_CACHE_HANDLING == TRUE
+// on F7 we check we are in the DTCM region, and 16 bit aligned
+#define IS_DMA_SAFE(addr) ((uint32_t(addr) & 0xFFFE0001) == 0x20000000)
+#else
 // this checks an address is in main memory and 16 bit aligned
-// on the STM32F7 we assume all memory is DMA safe, and call dma_flush()
-// and dma_invalidate() when needed
 #define IS_DMA_SAFE(addr) ((uint32_t(addr) & 0xF0000001) == 0x20000000)
+#endif
 
 class ChibiOS::Util : public AP_HAL::Util {
 public:

libraries/AP_HAL_ChibiOS/hwdef/common/malloc.c

@@ -30,13 +30,7 @@
 #include <chheap.h>
 #include <stdarg.h>
 
-#if defined(STM32F7) && STM32_DMA_CACHE_HANDLING == TRUE
-// to allow for dma management functions we need buffers to be
-// aligned to the cache line size
-#define MIN_ALIGNMENT 32
-#else
 #define MIN_ALIGNMENT 8
-#endif
 
 #if defined(CCM_RAM_SIZE)
 #ifndef CCM_BASE_ADDRESS
@@ -46,6 +40,11 @@ static memory_heap_t ccm_heap;
 static bool ccm_heap_initialised = false;
 #endif
 
+#if defined(DTCM_RAM_SIZE) && defined(DTCM_BASE_ADDRESS)
+static memory_heap_t dtcm_heap;
+static bool dtcm_heap_initialised = false;
+#endif
+
 void *malloc_ccm(size_t size)
 {
     void *p = NULL;
@@ -64,6 +63,24 @@ void *malloc_ccm(size_t size)
     return p;
 }
 
+void *malloc_dtcm(size_t size)
+{
+    void *p = NULL;
+#if defined(DTCM_RAM_SIZE)
+    if (!dtcm_heap_initialised) {
+        dtcm_heap_initialised = true;
+        chHeapObjectInit(&dtcm_heap, (void *)DTCM_BASE_ADDRESS, DTCM_RAM_SIZE*1024);
+    }
+    p = chHeapAllocAligned(&dtcm_heap, size, CH_HEAP_ALIGNMENT);
+    if (p != NULL) {
+        memset(p, 0, size);
+    }
+#else
+    (void)size;
+#endif
+    return p;
+}
+
 void *malloc(size_t size)
 {
     if (size == 0) {
@@ -72,11 +89,23 @@ void *malloc(size_t size)
     void *p = chHeapAllocAligned(NULL, size, MIN_ALIGNMENT);
     if (p) {
         memset(p, 0, size);
-    } else {
-        // fall back to CCM memory when main memory full
-        p = malloc_ccm(size);
+        return p;
     }
-    return p;
+    if (!p) {
+        // fall back to CCM memory
+        p = malloc_ccm(size);
+        if (p) {
+            return p;
+        }
+    }
+    if (!p) {
+        // fall back to DTCM memory
+        p = malloc_dtcm(size);
+        if (p) {
+            return p;
+        }
+    }
+    return NULL;
 }
 
 void *calloc(size_t nmemb, size_t size)
@@ -108,6 +137,12 @@ size_t mem_available(void)
     chHeapStatus(&ccm_heap, &ccm_available, NULL);
     totalp += ccm_available;
 #endif
+
+#if defined(DTCM_RAM_SIZE) && defined(DTCM_BASE_ADDRESS)
+    size_t dtcm_available = 0;
+    chHeapStatus(&dtcm_heap, &dtcm_available, NULL);
+    totalp += dtcm_available;
+#endif
     
     return totalp;
 }

libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat

@@ -5,9 +5,12 @@
 # but without the TFT interface
 MCU STM32F7xx STM32F767xx
 
-# we treat DTCM, SRAM1 and SRAM2 as a single memory region, but
-# use DMA management operations for all DMA transfers
-RAM_SIZE_KB 512
+# use SRAM1 and SRAM2 as main memory, giving the fastest possible
+# memory. Use DTCM for DMA memory as it needs no data cache operations
+RAM_SIZE_KB 384
+RAM_BASE_ADDRESS 0x20020000
+define DTCM_RAM_SIZE 128
+define DTCM_BASE_ADDRESS 0x20000000
 
 # crystal frequency
 OSCILLATOR_HZ 16000000

libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py

@@ -310,10 +310,16 @@ def get_config(name, column=0, required=True, default=None, type=None, spaces=Fa
         ret = config[name][column]
     
     if type is not None:
-        try:
-            ret = type(ret)
-        except Exception:
-            error("Badly formed config value %s (got %s)" % (name, ret))
+        if type == int and ret.startswith('0x'):
+            try:
+                ret = int(ret,16)
+            except Exception:
+                error("Badly formed config value %s (got %s)" % (name, ret))
+        else:
+            try:
+                ret = type(ret)
+            except Exception:
+                error("Badly formed config value %s (got %s)" % (name, ret))
     return ret
 
 def enable_can(f):
@@ -410,6 +416,7 @@ def write_ldscript(fname):
 
     # ram size
     ram_size = get_config('RAM_SIZE_KB', default=192, type=int)
+    ram_base = get_config('RAM_BASE_ADDRESS', default=0x20000000, type=int)
 
     flash_base = 0x08000000 + flash_reserve_start * 1024
     flash_length = flash_size - (flash_reserve_start + flash_reserve_end)
@@ -420,11 +427,11 @@ def write_ldscript(fname):
 MEMORY
 {
     flash : org = 0x%08x, len = %uK
-    ram0  : org = 0x20000000, len = %uk
+    ram0  : org = 0x%08x, len = %uk
 }
 
 INCLUDE common.ld
-''' % (flash_base, flash_length, ram_size))
+''' % (flash_base, flash_length, ram_base, ram_size))
 
 def copy_common_linkerscript(outdir, hwdef):
     dirpath = os.path.dirname(hwdef)