Implement DFU_UPLOAD.

src/platforms/stlink/Flashsize_F103

@@ -0,0 +1,39 @@
+Announced versus available Flash size on F103
+============================================
+Up to Stlink V2, the CPU soldered on the board was a F103C8 with 64 kiByte
+flash. Up to about version 280 of BMP, this limit was not hit when linked
+against nanolib.
+
+StlinkV2-1 has a STM32F103CB, like a genuine BMP.
+
+However with more and more devices supported, BMP at about version 282 hit
+this limit. There are two ways to work around:
+- Branch STlink V2-1 as separate platform and and care for the original STlink
+  platform by restricting/ommitting features.
+- Rely on uncertain upper flash on F103C8
+
+The first option needs more care as an additional platform is introduced and
+will restrict usage of older STlinks as BMPs.
+
+However F103C8 and F103CB have the same chip and upper flash exists on F103C8.
+This flash may have been tested bad, or not have been tested at all,
+or, in the best case, was tested good but market requirements made STM sell
+it as F103C8.
+
+Ignoring the chip marking and using an F103C8 blindly as a F103Cb is done
+already with few problems on many china boards (e.g. blue pill). Probably
+this second approach will work for many of the older STLinks.
+
+Use at your own risk!
+
+With DFU upload available in the bootloader, you can verify by uploading the
+binary from flash and comparing it against the binary downloaded.
+- Download new BMP binary (if not already done)
+  dfu-util -s 0x08002000:leave:force -D blackmagic.bin
+- Get length of binary
+  > ls -l blackmagic.bin
+  -rwxr-xr-x 1 bon users 57372 15. Apr 14:17 blackmagic.bin
+- Upload binary from flash
+  > dfu-util -s 0x08002000:leave:force:57372 -U blackmagic.bin.1
+- Compare
+  > diff blackmagic.bin*

src/platforms/stm32/dfucore.c

@@ -70,7 +70,7 @@ const struct usb_device_descriptor dev = {
 const struct usb_dfu_descriptor dfu_function = {
 	.bLength = sizeof(struct usb_dfu_descriptor),
 	.bDescriptorType = DFU_FUNCTIONAL,
-	.bmAttributes = USB_DFU_CAN_DOWNLOAD | USB_DFU_WILL_DETACH,
+	.bmAttributes = USB_DFU_CAN_DOWNLOAD | USB_DFU_CAN_UPLOAD | USB_DFU_WILL_DETACH,
 	.wDetachTimeout = 255,
 	.wTransferSize = 1024,
 	.bcdDFUVersion = 0x011A,
@@ -236,8 +236,22 @@ static int usbdfu_control_request(usbd_device *dev,
 		usbdfu_state = STATE_DFU_IDLE;
 		return 1;
 	case DFU_UPLOAD:
-		/* Upload not supported for now */
-		return 0;
+		if ((usbdfu_state == STATE_DFU_IDLE) ||
+			(usbdfu_state == STATE_DFU_DNLOAD_IDLE) ||
+			(usbdfu_state == STATE_DFU_UPLOAD_IDLE)) {
+			prog.blocknum = req->wValue;
+			usbdfu_state = STATE_DFU_UPLOAD_IDLE;
+			if(prog.blocknum > 1) {
+				uint32_t baseaddr = prog.addr +
+					((prog.blocknum - 2) *
+					 dfu_function.wTransferSize);
+				memcpy(*buf, (void*)baseaddr, *len);
+			}
+			return 1;
+		} else {
+			usbd_ep_stall_set(dev, 0, 1);
+			return 0;
+		}
 	case DFU_GETSTATUS: {
 		uint32_t bwPollTimeout = 0; /* 24-bit integer in DFU class spec */