HAL_ChibiOS: avoid malloc in usbcfg

this avoids the need for malloc in the bootloader

libraries/AP_HAL_ChibiOS/Scheduler.h

@@ -117,8 +117,10 @@ private:
 #if HAL_WITH_UAVCAN
     thread_t* _uavcan_thread_ctx;
 #endif
+#if CH_CFG_USE_SEMAPHORES == TRUE
     binary_semaphore_t _timer_semaphore;
     binary_semaphore_t _io_semaphore;
+#endif
     static void _timer_thread(void *arg);
     static void _rcin_thread(void *arg);
     static void _io_thread(void *arg);

libraries/AP_HAL_ChibiOS/hwdef/common/stdio.c

@@ -59,6 +59,11 @@ int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
       str[ms.eos] = 0;
 
   /* Return number of bytes that would have been written.*/
+#else
+  (void)str;
+  (void)size;
+  (void)fmt;
+  (void)ap;
 #endif
   return retval;
 }
@@ -75,6 +80,9 @@ int snprintf(char *str, size_t size, const char *fmt, ...)
  
    return done;
 #else
+   (void)str;
+   (void)size;
+   (void)fmt;
    return 0;
 #endif
 }
@@ -94,6 +102,9 @@ int vasprintf(char **strp, const char *fmt, va_list ap)
     (*strp) = buf;
     return len;
 #else
+    (void)strp;
+    (void)fmt;
+    (void)ap;
     return 0;
 #endif
 }
@@ -107,6 +118,8 @@ int asprintf(char **strp, const char *fmt, ...)
     va_end(ap);
     return ret;
 #else
+    (void)strp;
+    (void)fmt;
     return 0;
 #endif
 }
@@ -136,6 +149,7 @@ int printf(const char *fmt, ...)
  
    return done;
 #else
+   (void)fmt;
    return 0;
 #endif
 }

libraries/AP_HAL_ChibiOS/hwdef/common/stubs.c

@@ -152,7 +152,7 @@ int _close(struct _reent *r, int file)
 __attribute__((used))
 caddr_t _sbrk(struct _reent *r, int incr)
 {
-#if CH_CFG_USE_MEMCORE
+#if CH_CFG_USE_MEMCORE && CH_CFG_USE_HEAP == TRUE
   void *p;
 
   chDbgCheck(incr >= 0);

libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.c

@@ -178,6 +178,9 @@ static USBDescriptor vcom_strings[] = {
   {0, NULL}, // version
 };
 
+#define USB_DESC_MAX_STRLEN 100
+static uint8_t vcom_buffers[3][2+2*USB_DESC_MAX_STRLEN];
+
 /*
   check if one string contains another
  */
@@ -196,7 +199,7 @@ static bool string_contains(const char *haystack, const char *needle)
 /*
   handle substitution of variables in strings for USB descriptors
  */
-static char *string_substitute(const char *str)
+static void string_substitute(const char *str, char *str2)
 {
     uint8_t new_len = strlen(str);
     if (string_contains(str, "%BOARD%")) {
@@ -205,7 +208,10 @@ static char *string_substitute(const char *str)
     if (string_contains(str, "%SERIAL%")) {
         new_len += 24 - 8;
     }
-    char *str2 = malloc(new_len+1);
+    if (new_len+1 > USB_DESC_MAX_STRLEN) {
+        strcpy(str2, str);
+        return;
+    }
     char *p = str2;
     while (*str) {
         char c = *str;
@@ -231,19 +237,18 @@ static char *string_substitute(const char *str)
         *p++ = *str++;
     }
     *p = 0;
-    return str2;
 }
 
 
 /*
   dynamically allocate a USB descriptor string
  */
-static void setup_usb_string(USBDescriptor *desc, const char *str)
+static void setup_usb_string(USBDescriptor *desc, const char *str, uint8_t *b)
 {
-    char *str2 = string_substitute(str);
+    char str2[USB_DESC_MAX_STRLEN];
+    string_substitute(str, str2);
     uint8_t len = strlen(str2);
     desc->ud_size = 2+2*len;
-    uint8_t *b = (uint8_t *)calloc(1, desc->ud_size);
     desc->ud_string = (const uint8_t *)b;
     b[0] = USB_DESC_BYTE(desc->ud_size);
     b[1] = USB_DESC_BYTE(USB_DESCRIPTOR_STRING);
@@ -252,9 +257,6 @@ static void setup_usb_string(USBDescriptor *desc, const char *str)
         b[2+i*2] = str2[i];
         b[2+i*2+1] = 0;
     }
-    if (str2 != str) {
-        free(str2);
-    }
 }
 
 /*
@@ -262,9 +264,9 @@ static void setup_usb_string(USBDescriptor *desc, const char *str)
  */
 void setup_usb_strings(void)
 {
-    setup_usb_string(&vcom_strings[1], HAL_USB_STRING_MANUFACTURER);
-    setup_usb_string(&vcom_strings[2], HAL_USB_STRING_PRODUCT);
-    setup_usb_string(&vcom_strings[3], HAL_USB_STRING_SERIAL);
+    setup_usb_string(&vcom_strings[1], HAL_USB_STRING_MANUFACTURER, vcom_buffers[0]);
+    setup_usb_string(&vcom_strings[2], HAL_USB_STRING_PRODUCT, vcom_buffers[1]);
+    setup_usb_string(&vcom_strings[3], HAL_USB_STRING_SERIAL, vcom_buffers[2]);
 }
 
 /*

libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py

@@ -453,7 +453,8 @@ def write_mcu_config(f):
 #define CH_CFG_USE_DYNAMIC FALSE
 #define CH_CFG_USE_MEMPOOLS FALSE
 #define CH_DBG_FILL_THREADS FALSE
-#define CH_CFG_USE_SEMAPHORES TRUE
+#define CH_CFG_USE_SEMAPHORES FALSE
+#define CH_CFG_USE_HEAP FALSE        
 #define CH_CFG_USE_MUTEXES FALSE
 #define CH_CFG_USE_CONDVARS FALSE
 #define CH_CFG_USE_CONDVARS_TIMEOUT FALSE