From fbd3fa1ca9ff01dd7f67502b9549da62e5f8279f Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Mon, 24 Feb 2020 15:58:22 +0100
Subject: [PATCH] DFU: Flash first page last

---
 bsb/bootloader/config.h |  6 ++--
 lib/dfu-bootloader.c    | 71 ++++++++++++++++++++++++++---------------
 2 files changed, 48 insertions(+), 29 deletions(-)

diff --git a/bsb/bootloader/config.h b/bsb/bootloader/config.h
index 232fd4a..6900748 100644
--- a/bsb/bootloader/config.h
+++ b/bsb/bootloader/config.h
@@ -18,7 +18,7 @@
 #define BOOTLOADER_DEBUG
 #define BOOTLOADER_APP_START 0x08002000
 #define BOOTLOADER_MFG_ID 0x4242
-#define BOOTLOADER_DEV_ID 0x0004
-#define BOOTLOADER_DEV_VERSION 0x0100
+#define BOOTLOADER_PROD_ID 0x0004
+#define BOOTLOADER_PROD_VERSION 0x0100
 #define BOOTLOADER_MFG_NAME "United Computer Wizards"
-#define BOOTLOADER_DEV_NAME "BSB Interface (boot-loader)"
+#define BOOTLOADER_PROD_NAME "BSB Interface (boot-loader)"
diff --git a/lib/dfu-bootloader.c b/lib/dfu-bootloader.c
index 4f792ce..ce01a41 100644
--- a/lib/dfu-bootloader.c
+++ b/lib/dfu-bootloader.c
@@ -35,24 +35,29 @@ byte usbd_control_buffer[1024];
 
 static enum dfu_state usbdfu_state = STATE_DFU_IDLE;
 
-static struct {
+struct prog_info {
 	byte buf[sizeof(usbd_control_buffer)];
-	u16 len;
-	u32 addr;
 	u16 blocknum;
-} prog;
+	u16 len;
+};
+
+static struct prog_info prog_page;
+
+// The first page of application code is programmed last,
+// so that we are able to detect incompletely uploaded firmware.
+static struct prog_info prog_header;
 
 static char usb_serial_number[13];
 
 enum usb_string {
 	STR_MANUFACTURER = 1,
-	STR_DEVICE,
+	STR_PRODUCT,
 	STR_SERIAL,
 };
 
 static const char *usb_strings[] = {
 	BOOTLOADER_MFG_NAME,
-	BOOTLOADER_DEV_NAME,
+	BOOTLOADER_PROD_NAME,
 	usb_serial_number,
 };
 
@@ -65,10 +70,10 @@ const struct usb_device_descriptor dev = {
 	.bDeviceProtocol = 0,
 	.bMaxPacketSize0 = 64,
 	.idVendor = BOOTLOADER_MFG_ID,
-	.idProduct = BOOTLOADER_DEV_ID,
-	.bcdDevice = BOOTLOADER_DEV_VERSION,
+	.idProduct = BOOTLOADER_PROD_ID,
+	.bcdDevice = BOOTLOADER_PROD_VERSION,
 	.iManufacturer = STR_MANUFACTURER,
-	.iProduct = STR_DEVICE,
+	.iProduct = STR_PRODUCT,
 	.iSerialNumber = STR_SERIAL,
 	.bNumConfigurations = 1,
 };
@@ -128,23 +133,37 @@ static byte usbdfu_getstatus(usbd_device *usbd_dev UNUSED, u32 *bwPollTimeout)
 	}
 }
 
+static void program_page(struct prog_info *prog, bool need_erase)
+{
+	flash_unlock();
+	u32 baseaddr = BOOTLOADER_APP_START + prog->blocknum * dfu_function.wTransferSize;
+	DEBUG("DFU: Block %u -> %08x\n", prog->blocknum, (uint) baseaddr);
+	if (need_erase)
+		flash_erase_page(baseaddr);
+	for (uint i = 0; i < prog->len; i += 2) {
+		u16 data = *(u16 *)(prog->buf + i);
+		flash_program_half_word(baseaddr + i, data);
+	}
+	flash_lock();
+}
+
 static void usbdfu_getstatus_complete(usbd_device *usbd_dev UNUSED, struct usb_setup_data *req UNUSED)
 {
 	switch (usbdfu_state) {
-	case STATE_DFU_DNBUSY: {
-		flash_unlock();
-		u32 baseaddr = BOOTLOADER_APP_START + prog.blocknum * dfu_function.wTransferSize;
-		DEBUG("DFU: Block %u -> %08x\n", prog.blocknum, (uint) baseaddr);
-		flash_erase_page(baseaddr);
-		for (uint i = 0; i < prog.len; i += 2) {
-			u16 *dat = (u16 *)(prog.buf + i);
-			flash_program_half_word(baseaddr + i, *dat);
-		}
-		flash_lock();
+	case STATE_DFU_DNBUSY:
+		if (prog_page.blocknum == 0) {
+			// The first block will be programmed last
+			prog_header = prog_page;
+			flash_unlock();
+			flash_erase_page(BOOTLOADER_APP_START);
+			flash_lock();
+		} else
+			program_page(&prog_page, true);
 		usbdfu_state = STATE_DFU_DNLOAD_IDLE;
 		return;
-		}
 	case STATE_DFU_MANIFEST:
+		// At the very end, program the first page
+		program_page(&prog_header, false);
 		/* USB device must detach, we just reset... */
 		scb_reset_system();
 		return; /* Will never return. */
@@ -162,7 +181,7 @@ static enum usbd_request_return_codes usbdfu_control_request(usbd_device *usbd_d
 	if ((req->bmRequestType & 0x7F) != 0x21)
 		return USBD_REQ_NOTSUPP; /* Only accept class request. */
 
-	DEBUG("DFU: req %02x in state %d\n", req->bRequest, usbdfu_state);
+	DEBUG("DFU: Request %02x in state %d\n", req->bRequest, usbdfu_state);
 
 	switch (req->bRequest) {
 	case DFU_DNLOAD:
@@ -170,9 +189,9 @@ static enum usbd_request_return_codes usbdfu_control_request(usbd_device *usbd_d
 			usbdfu_state = STATE_DFU_MANIFEST_SYNC;
 		} else {
 			/* Copy download data for use on GET_STATUS. */
-			prog.blocknum = req->wValue;
-			prog.len = *len;
-			memcpy(prog.buf, *buf, *len);
+			prog_page.blocknum = req->wValue;
+			prog_page.len = *len;
+			memcpy(prog_page.buf, *buf, *len);
 			usbdfu_state = STATE_DFU_DNLOAD_SYNC;
 		}
 		return USBD_REQ_HANDLED;
@@ -273,7 +292,7 @@ int main(void)
 	// Simulate USB disconnect
 	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO11 | GPIO12);
 	gpio_clear(GPIOA, GPIO11 | GPIO12);
-	for (uint i=0; i<1000; i++) {
+	for (uint i=0; i<100; i++) {
 		while (!systick_get_countflag())
 			;
 	}
@@ -302,7 +321,7 @@ restart: ;
 	u32 pc = app[1];
 
 	DEBUG("DFU: Starting application (sp=%08x, pc=%08x)\n", (uint) sp, (uint) pc);
-	if (sp & 0x2ffe0000 != 0x20000000) {
+	if ((sp & 0x2ffe0000) != 0x20000000) {
 		DEBUG("DFU: Suspicious SP, refusing to start\n");
 		goto restart;
 	}
-- 
2.39.5