diff --git a/Makefile b/Makefile
index a3446b00..db9178f4 100644
--- a/Makefile
+++ b/Makefile
@@ -4,15 +4,18 @@ Q := @
 endif
 
 PC_HOSTED =
+NO_LIBOPENCM3 =
 ifeq ($(PROBE_HOST), libftdi)
 	PC_HOSTED = true
+	NO_LIBOPENCM3 = true
 endif
 ifeq ($(PROBE_HOST), pc-stlinkv2)
 	PC_HOSTED = true
+	NO_LIBOPENCM3 = true
 endif
 
 all:
-ifndef 	PC_HOSTED
+ifndef NO_LIBOPENCM3
 	$(Q)if [ ! -f libopencm3/Makefile ]; then \
 		echo "Initialising git submodules..." ;\
 		git submodule init ;\
@@ -23,7 +26,7 @@ endif
 	$(Q)$(MAKE) $(MFLAGS) -C src
 
 clean:
-ifndef 	PC_HOSTED
+ifndef NO_LIBOPENCM3
 	$(Q)$(MAKE) $(MFLAGS) -C libopencm3 $@
 endif
 	$(Q)$(MAKE) $(MFLAGS) -C src $@
diff --git a/libopencm3 b/libopencm3
index 46e315bf..f86c4646 160000
--- a/libopencm3
+++ b/libopencm3
@@ -1 +1 @@
-Subproject commit 46e315bf2b3da94dbaec7671541e8ad2b2f87a75
+Subproject commit f86c46467d94c0160c2f58044675e42f1a8fdb7c
diff --git a/src/Makefile b/src/Makefile
index 1bc4b8fc..dfc61870 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -8,12 +8,9 @@ MAKEFLAGS += --no-print-dir
 Q := @
 endif
 
-OPT_FLAGS ?= -O2
-
 CFLAGS += -Wall -Wextra -Werror -Wno-char-subscripts -Wno-cast-function-type \
-	$(OPT_FLAGS) -std=gnu99 -g3 -MD \
+	-std=gnu99 -g3 -MD \
 	-I. -Iinclude -Iplatforms/common -I$(PLATFORM_DIR)
-LDFLAGS += $(OPT_FLAGS)
 
 ifeq ($(ENABLE_DEBUG), 1)
 CFLAGS += -DENABLE_DEBUG -g3 -ggdb
@@ -60,6 +57,10 @@ SRC =			\
 
 include $(PLATFORM_DIR)/Makefile.inc
 
+OPT_FLAGS ?= -O2
+CFLAGS += $(OPT_FLAGS)
+LDFLAGS += $(OPT_FLAGS)
+
 ifndef TARGET
 TARGET=blackmagic
 endif
@@ -72,7 +73,7 @@ ifndef OWN_HL
 SRC += jtag_scan.c jtagtap.c swdptap.c
 endif
 
-OBJ = $(SRC:.c=.o)
+OBJ = $(patsubst %.S,%.o,$(patsubst %.c,%.o,$(SRC)))
 
 $(TARGET): include/version.h $(OBJ)
 	@echo "  LD      $@"
@@ -82,6 +83,10 @@ $(TARGET): include/version.h $(OBJ)
 	@echo "  CC      $<"
 	$(Q)$(CC) $(CFLAGS) -c $< -o $@
 
+%.o:	%.S
+	@echo "  AS      $<"
+	$(Q)$(CC) $(CFLAGS) -c $< -o $@
+
 %.bin:	%
 	@echo "  OBJCOPY $@"
 	$(Q)$(OBJCOPY) $(OBJCOPY_FLAGS) -O binary $^ $@
diff --git a/src/gdb_packet.c b/src/gdb_packet.c
index f738996a..0396e0d3 100644
--- a/src/gdb_packet.c
+++ b/src/gdb_packet.c
@@ -120,7 +120,7 @@ void gdb_putpacket(const char *packet, int size)
 			}
 		}
 		gdb_if_putchar('#', 0);
-		sprintf(xmit_csum, "%02X", csum);
+		snprintf(xmit_csum, sizeof(xmit_csum), "%02X", csum);
 		gdb_if_putchar(xmit_csum[0], 0);
 		gdb_if_putchar(xmit_csum[1], 1);
 #ifdef DEBUG_GDBPACKET
diff --git a/src/include/gdb_if.h b/src/include/gdb_if.h
index d2ad2439..1dc9e28d 100644
--- a/src/include/gdb_if.h
+++ b/src/include/gdb_if.h
@@ -21,7 +21,7 @@
 #ifndef __GDB_IF_H
 #define __GDB_IF_H
 
-#if !defined(PC_HOSTED)
+#if !defined(NO_LIBOPENCM3)
 #include <libopencm3/usb/usbd.h>
 void gdb_usb_out_cb(usbd_device *dev, uint8_t ep);
 #endif
diff --git a/src/platforms/common/cdcacm.c b/src/platforms/common/cdcacm.c
index 7190ac01..d45adb89 100644
--- a/src/platforms/common/cdcacm.c
+++ b/src/platforms/common/cdcacm.c
@@ -423,7 +423,7 @@ static void dfu_detach_complete(usbd_device *dev, struct usb_setup_data *req)
 #endif
 }
 
-static int cdcacm_control_request(usbd_device *dev,
+static enum usbd_request_return_codes  cdcacm_control_request(usbd_device *dev,
 		struct usb_setup_data *req, uint8_t **buf, uint16_t *len,
 		void (**complete)(usbd_device *dev, struct usb_setup_data *req))
 {
@@ -437,23 +437,23 @@ static int cdcacm_control_request(usbd_device *dev,
 		cdcacm_set_modem_state(dev, req->wIndex, true, true);
 		/* Ignore if not for GDB interface */
 		if(req->wIndex != 0)
-			return 1;
+			return USBD_REQ_HANDLED;
 
 		cdcacm_gdb_dtr = req->wValue & 1;
 
-		return 1;
+		return USBD_REQ_HANDLED;
 	case USB_CDC_REQ_SET_LINE_CODING:
 		if(*len < sizeof(struct usb_cdc_line_coding))
-			return 0;
+			return USBD_REQ_NOTSUPP;
 
 		switch(req->wIndex) {
 		case 2:
 			usbuart_set_line_coding((struct usb_cdc_line_coding*)*buf);
-			return 1;
+			return USBD_REQ_HANDLED;
 		case 0:
-			return 1; /* Ignore on GDB Port */
+			return USBD_REQ_HANDLED; /* Ignore on GDB Port */
 		default:
-			return 0;
+			return USBD_REQ_NOTSUPP;
 		}
 	case DFU_GETSTATUS:
 		if(req->wIndex == DFU_IF_NO) {
@@ -465,17 +465,17 @@ static int cdcacm_control_request(usbd_device *dev,
 			(*buf)[5] = 0;	/* iString not used here */
 			*len = 6;
 
-			return 1;
+			return USBD_REQ_HANDLED;
 		}
-		return 0;
+		return USBD_REQ_NOTSUPP;
 	case DFU_DETACH:
 		if(req->wIndex == DFU_IF_NO) {
 			*complete = dfu_detach_complete;
-			return 1;
+			return USBD_REQ_HANDLED;
 		}
-		return 0;
+		return USBD_REQ_NOTSUPP;
 	}
-	return 0;
+	return USBD_REQ_NOTSUPP;
 }
 
 int cdcacm_get_config(void)
diff --git a/src/platforms/f4discovery/platform.c b/src/platforms/f4discovery/platform.c
index 89b82c16..4703317d 100644
--- a/src/platforms/f4discovery/platform.c
+++ b/src/platforms/f4discovery/platform.c
@@ -62,7 +62,7 @@ void platform_init(void)
 		scb_reset_core();
 	}
 
-	rcc_clock_setup_hse_3v3(&rcc_hse_8mhz_3v3[RCC_CLOCK_3V3_48MHZ]);
+	rcc_clock_setup_pll(&rcc_hse_8mhz_3v3[RCC_CLOCK_3V3_168MHZ]);
 
 	/* Enable peripherals */
 	rcc_periph_clock_enable(RCC_OTGFS);
diff --git a/src/platforms/hydrabus/platform.c b/src/platforms/hydrabus/platform.c
index bf3db04b..e0893e8c 100644
--- a/src/platforms/hydrabus/platform.c
+++ b/src/platforms/hydrabus/platform.c
@@ -46,7 +46,7 @@ void platform_init(void)
 		scb_reset_core();
 	}
 
-	rcc_clock_setup_hse_3v3(&rcc_hse_8mhz_3v3[RCC_CLOCK_3V3_48MHZ]);
+	rcc_clock_setup_pll(&rcc_hse_8mhz_3v3[RCC_CLOCK_3V3_168MHZ]);
 
 	/* Enable peripherals */
 	rcc_peripheral_enable_clock(&RCC_AHB2ENR, RCC_AHB2ENR_OTGFSEN);
diff --git a/src/platforms/jeff/usbdfu.c b/src/platforms/jeff/usbdfu.c
index 67d54949..4efc6000 100644
--- a/src/platforms/jeff/usbdfu.c
+++ b/src/platforms/jeff/usbdfu.c
@@ -143,10 +143,8 @@ static const char *usb_strings[] = {
 	//"@Internal Flash   /0x00000000/1*0016Ka,15*0016Kg",
 };
 
-static uint8_t usbdfu_getstatus(usbd_device *usbd_dev, uint32_t *bwPollTimeout)
+static uint8_t usbdfu_getstatus(uint32_t *bwPollTimeout)
 {
-	(void)usbd_dev;
-
 	switch (usbdfu_state) {
 	case STATE_DFU_DNLOAD_SYNC:
 		usbdfu_state = STATE_DFU_DNBUSY;
@@ -225,9 +223,12 @@ static void usbdfu_getstatus_complete(usbd_device *usbd_dev, struct usb_setup_da
 	}
 }
 
-static int usbdfu_control_request(usbd_device *usbd_dev, struct usb_setup_data *req, uint8_t **buf,
-		uint16_t *len, void (**complete)(usbd_device *usbd_dev, struct usb_setup_data *req))
+static enum usbd_request_return_codes usbdfu_control_request(usbd_device *dev,
+		struct usb_setup_data *req, uint8_t **buf, uint16_t *len,
+		void (**complete)(usbd_device *dev, struct usb_setup_data *req))
 {
+	(void)dev;
+
 	if ((req->bmRequestType & 0x7F) != 0x21)
 		return 0; /* Only accept class request. */
 
@@ -258,7 +259,7 @@ static int usbdfu_control_request(usbd_device *usbd_dev, struct usb_setup_data *
 		return 0;
 	case DFU_GETSTATUS: {
 		uint32_t bwPollTimeout = 0; /* 24-bit integer in DFU class spec */
-		(*buf)[0] = usbdfu_getstatus(usbd_dev, &bwPollTimeout);
+		(*buf)[0] = usbdfu_getstatus(&bwPollTimeout);
 		(*buf)[1] = bwPollTimeout & 0xFF;
 		(*buf)[2] = (bwPollTimeout >> 8) & 0xFF;
 		(*buf)[3] = (bwPollTimeout >> 16) & 0xFF;
diff --git a/src/platforms/launchpad-icdi/platform.h b/src/platforms/launchpad-icdi/platform.h
index a710c52b..7450aa74 100644
--- a/src/platforms/launchpad-icdi/platform.h
+++ b/src/platforms/launchpad-icdi/platform.h
@@ -68,7 +68,7 @@ extern uint8_t running_status;
 	gpio_set_output_config(SWDIO_PORT, GPIO_OTYPE_PP, GPIO_DRIVE_2MA, SWDIO_PIN);		\
 }
 
-extern usbd_driver lm4f_usb_driver;
+extern const usbd_driver lm4f_usb_driver;
 #define USB_DRIVER	lm4f_usb_driver
 #define USB_IRQ		NVIC_USB0_IRQ
 #define USB_ISR		usb0_isr
diff --git a/src/platforms/libftdi/Makefile.inc b/src/platforms/libftdi/Makefile.inc
index 06c07d76..0ddabe89 100644
--- a/src/platforms/libftdi/Makefile.inc
+++ b/src/platforms/libftdi/Makefile.inc
@@ -1,5 +1,5 @@
 SYS = $(shell $(CC) -dumpmachine)
-CFLAGS += -DPC_HOSTED -DENABLE_DEBUG
+CFLAGS += -DPC_HOSTED -DNO_LIBOPENCM3 -DENABLE_DEBUG
 LDFLAGS += -lftdi1
 ifneq (, $(findstring mingw, $(SYS)))
 LDFLAGS +=  -lusb-1.0 -lws2_32
diff --git a/src/platforms/pc-stlinkv2/Makefile.inc b/src/platforms/pc-stlinkv2/Makefile.inc
index 53ec16a1..8762885d 100644
--- a/src/platforms/pc-stlinkv2/Makefile.inc
+++ b/src/platforms/pc-stlinkv2/Makefile.inc
@@ -1,6 +1,6 @@
 TARGET=blackmagic_stlinkv2
 SYS = $(shell $(CC) -dumpmachine)
-CFLAGS += -DPC_HOSTED  -DSTLINKV2 -DJTAG_HL -DENABLE_DEBUG
+CFLAGS += -DPC_HOSTED -DNO_LIBOPENCM3 -DSTLINKV2 -DJTAG_HL -DENABLE_DEBUG
 CFLAGS +=-I ./target
 LDFLAGS += -lusb-1.0
 ifneq (, $(findstring mingw, $(SYS)))
diff --git a/src/platforms/stm32/blackmagic.ld b/src/platforms/stm32/blackmagic.ld
index 9755309e..c1d1ce78 100644
--- a/src/platforms/stm32/blackmagic.ld
+++ b/src/platforms/stm32/blackmagic.ld
@@ -25,5 +25,5 @@ MEMORY
 }
 
 /* Include the common ld script from libopenstm32. */
-INCLUDE libopencm3_stm32f1.ld
+INCLUDE cortex-m-generic.ld
 
diff --git a/src/platforms/stm32/dfucore.c b/src/platforms/stm32/dfucore.c
index 61cfd041..adeff9ae 100644
--- a/src/platforms/stm32/dfucore.c
+++ b/src/platforms/stm32/dfucore.c
@@ -198,20 +198,20 @@ usbdfu_getstatus_complete(usbd_device *dev, struct usb_setup_data *req)
 	}
 }
 
-static int usbdfu_control_request(usbd_device *dev,
+static enum usbd_request_return_codes usbdfu_control_request(usbd_device *dev,
 		struct usb_setup_data *req, uint8_t **buf, uint16_t *len,
 		void (**complete)(usbd_device *dev, struct usb_setup_data *req))
 {
 	(void)dev;
 
 	if((req->bmRequestType & 0x7F) != 0x21)
-		return 0; /* Only accept class request */
+		return USBD_REQ_NOTSUPP; /* Only accept class request */
 
 	switch(req->bRequest) {
 	case DFU_DNLOAD:
 		if((len == NULL) || (*len == 0)) {
 			usbdfu_state = STATE_DFU_MANIFEST_SYNC;
-			return 1;
+			return USBD_REQ_HANDLED;
 		} else {
 			/* Copy download data for use on GET_STATUS */
 			prog.blocknum = req->wValue;
@@ -222,22 +222,22 @@ static int usbdfu_control_request(usbd_device *dev,
 				if ((addr < app_address) || (addr >= max_address)) {
 					current_error = DFU_STATUS_ERR_TARGET;
 					usbdfu_state = STATE_DFU_ERROR;
-					return 1;
+					return USBD_REQ_HANDLED;
 				} else
 					prog.addr = addr;
 			}
 			usbdfu_state = STATE_DFU_DNLOAD_SYNC;
-			return 1;
+			return USBD_REQ_HANDLED;
 		}
 	case DFU_CLRSTATUS:
 		/* Clear error and return to dfuIDLE */
 		if(usbdfu_state == STATE_DFU_ERROR)
 			usbdfu_state = STATE_DFU_IDLE;
-		return 1;
+		return USBD_REQ_HANDLED;
 	case DFU_ABORT:
 		/* Abort returns to dfuIDLE state */
 		usbdfu_state = STATE_DFU_IDLE;
-		return 1;
+		return USBD_REQ_HANDLED;
 	case DFU_UPLOAD:
 		if ((usbdfu_state == STATE_DFU_IDLE) ||
 			(usbdfu_state == STATE_DFU_DNLOAD_IDLE) ||
@@ -250,10 +250,10 @@ static int usbdfu_control_request(usbd_device *dev,
 					 dfu_function.wTransferSize);
 				memcpy(*buf, (void*)baseaddr, *len);
 			}
-			return 1;
+			return USBD_REQ_HANDLED;
 		} else {
 			usbd_ep_stall_set(dev, 0, 1);
-			return 0;
+			return USBD_REQ_NOTSUPP;
 		}
 	case DFU_GETSTATUS: {
 		uint32_t bwPollTimeout = 0; /* 24-bit integer in DFU class spec */
@@ -268,16 +268,16 @@ static int usbdfu_control_request(usbd_device *dev,
 
 		*complete = usbdfu_getstatus_complete;
 
-		return 1;
+		return USBD_REQ_HANDLED;
 		}
 	case DFU_GETSTATE:
 		/* Return state with no state transision */
 		*buf[0] = usbdfu_state;
 		*len = 1;
-		return 1;
+		return USBD_REQ_HANDLED;
 	}
 
-	return 0;
+	return USBD_REQ_NOTSUPP;
 }
 
 void dfu_init(const usbd_driver *driver, dfu_mode_t mode)
diff --git a/src/platforms/stm32/f4discovery.ld b/src/platforms/stm32/f4discovery.ld
index b0664264..812d2ebb 100644
--- a/src/platforms/stm32/f4discovery.ld
+++ b/src/platforms/stm32/f4discovery.ld
@@ -25,5 +25,5 @@ MEMORY
 }
 
 /* Include the common ld script from libopenstm32. */
-INCLUDE libopencm3_stm32f4.ld
+INCLUDE cortex-m-generic.ld
 
diff --git a/src/platforms/stm32/stlink.ld b/src/platforms/stm32/stlink.ld
index 3b4af4ea..64a3a846 100644
--- a/src/platforms/stm32/stlink.ld
+++ b/src/platforms/stm32/stlink.ld
@@ -25,4 +25,4 @@ MEMORY
 }
 
 /* Include the common ld script from libopenstm32. */
-INCLUDE libopencm3_stm32f1.ld
+INCLUDE cortex-m-generic.ld
diff --git a/src/platforms/stm32/stm32_can.ld b/src/platforms/stm32/stm32_can.ld
index 86861b8d..0b497fcd 100644
--- a/src/platforms/stm32/stm32_can.ld
+++ b/src/platforms/stm32/stm32_can.ld
@@ -25,4 +25,4 @@ MEMORY
 }
 
 /* Include the common ld script from libopenstm32. */
-INCLUDE libopencm3_stm32f1.ld
+INCLUDE cortex-m-generic.ld
diff --git a/src/platforms/stm32/traceswo.c b/src/platforms/stm32/traceswo.c
index 50073788..25ae60a0 100644
--- a/src/platforms/stm32/traceswo.c
+++ b/src/platforms/stm32/traceswo.c
@@ -42,8 +42,6 @@ void traceswo_init(void)
 {
 	TRACE_TIM_CLK_EN();
 
-	timer_reset(TRACE_TIM);
-
 	/* Refer to ST doc RM0008 - STM32F10xx Reference Manual.
 	 * Section 14.3.4 - 14.3.6 (General Purpose Timer - Input Capture)
 	 *
diff --git a/src/platforms/stm32/usbuart.c b/src/platforms/stm32/usbuart.c
index a466ab55..ddcda807 100644
--- a/src/platforms/stm32/usbuart.c
+++ b/src/platforms/stm32/usbuart.c
@@ -68,7 +68,6 @@ void usbuart_init(void)
 
 	/* Setup timer for running deferred FIFO processing */
 	USBUSART_TIM_CLK_EN();
-	timer_reset(USBUSART_TIM);
 	timer_set_mode(USBUSART_TIM, TIM_CR1_CKD_CK_INT,
 			TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
 	timer_set_prescaler(USBUSART_TIM,
diff --git a/src/platforms/tm4c/tm4c.ld b/src/platforms/tm4c/tm4c.ld
index 8fe93a40..c2169c7e 100644
--- a/src/platforms/tm4c/tm4c.ld
+++ b/src/platforms/tm4c/tm4c.ld
@@ -25,5 +25,5 @@ MEMORY
 }
 
 /* Include the common ld script from libopenstm32. */
-INCLUDE libopencm3_lm4f.ld
+INCLUDE cortex-m-generic.ld
 
diff --git a/src/target/efm32.c b/src/target/efm32.c
index fff186ba..4405d99a 100644
--- a/src/target/efm32.c
+++ b/src/target/efm32.c
@@ -611,7 +611,7 @@ bool efm32_probe(target *t)
 	uint32_t ram_size   = ram_kib   * 0x400;
 	uint32_t flash_page_size = device->flash_page_size;
 
-	sprintf(variant_string, "%c\b%c\b%s %d F%d %s",
+	snprintf(variant_string, sizeof(variant_string), "%c\b%c\b%s %d F%d %s",
 			di_version + 48, (uint8_t)device_index + 32,
 			device->name, part_number, flash_kib, device->description);
 
diff --git a/src/target/samd.c b/src/target/samd.c
index 588ca83c..3117f2ae 100644
--- a/src/target/samd.c
+++ b/src/target/samd.c
@@ -364,7 +364,7 @@ static void samd_add_flash(target *t, uint32_t addr, size_t length)
 	target_add_flash(t, f);
 }
 
-char variant_string[40];
+char variant_string[60];
 bool samd_probe(target *t)
 {
 	uint32_t cid = samd_read_cid(t);
@@ -390,15 +390,15 @@ bool samd_probe(target *t)
 
 	/* Part String */
 	if (protected) {
-		sprintf(variant_string,
-		        "Atmel SAMD%d%c%dA%s (rev %c) (PROT=1)",
-		        samd.series, samd.pin, samd.mem,
-		        samd.package, samd.revision);
+		snprintf(variant_string, sizeof(variant_string),
+		         "Atmel SAMD%d%c%dA%s (rev %c) (PROT=1)",
+		         samd.series, samd.pin, samd.mem,
+		         samd.package, samd.revision);
 	} else {
-		sprintf(variant_string,
-		        "Atmel SAMD%d%c%dA%s (rev %c)",
-		        samd.series, samd.pin, samd.mem,
-		        samd.package, samd.revision);
+		snprintf(variant_string, sizeof(variant_string),
+		         "Atmel SAMD%d%c%dA%s (rev %c)",
+		         samd.series, samd.pin, samd.mem,
+		         samd.package, samd.revision);
 	}
 
 	/* Setup Target */