DFU: Introduce board/app-specific override for booting in DFU mode
Using the USBDFU_OverrideEnterDFU() function, a board/application can
define extra conditions when the system should boot in DFU mode, even if
it was not explicitly switched to DFU mode from the application.
The app/dfu/main.c uses this mechanism to boot into DFU mode if the
stack + reset vector addresses are not plausible (i.e. some random junk
appears to be flashed in the application partition) or if the user
places a jumper accross the RxD+TxD lines of the debug UART. The idea
is that the system can be recovered by placing this jumper and then
re-installing the application from DFU.
diff --git a/firmware/apps/dfu/main.c b/firmware/apps/dfu/main.c
index 07441e5..32c855c 100644
--- a/firmware/apps/dfu/main.c
+++ b/firmware/apps/dfu/main.c
@@ -103,6 +103,57 @@
return req_len;
}
+static int uart_has_loopback_jumper(void)
+{
+ unsigned int i;
+ const Pin uart_loopback_pins[] = {
+ {PIO_PA9A_URXD0, PIOA, ID_PIOA, PIO_INPUT, PIO_DEFAULT},
+ {PIO_PA10A_UTXD0, PIOA, ID_PIOA, PIO_OUTPUT_0, PIO_DEFAULT}
+ };
+
+ /* Configure UART pins as I/O */
+ PIO_Configure(uart_loopback_pins, PIO_LISTSIZE(uart_loopback_pins));
+
+ for (i = 0; i < 10; i++) {
+ /* Set TxD high; abort if RxD doesn't go high either */
+ PIO_Set(&uart_loopback_pins[1]);
+ if (!PIO_Get(&uart_loopback_pins[0]))
+ return 0;
+ /* Set TxD low, abort if RxD doesn't go low either */
+ PIO_Clear(&uart_loopback_pins[1]);
+ if (PIO_Get(&uart_loopback_pins[0]))
+ return 0;
+ }
+ /* if we reached here, RxD always follows TxD and thus a
+ * loopback jumper has been placed on RxD/TxD, and we will boot
+ * into DFU unconditionally */
+ return 1;
+}
+
+/* using this function we can determine if we should enter DFU mode
+ * during boot, or if we should proceed towards the application/runtime */
+int USBDFU_OverrideEnterDFU(void)
+{
+ uint32_t *app_part = (uint32_t *)FLASH_ADDR(0);
+
+ /* If the loopback jumper is set, we enter DFU mode */
+ if (uart_has_loopback_jumper())
+ return 1;
+
+ /* if the first word of the application partition doesn't look
+ * like a stack pointer (i.e. point to RAM), enter DFU mode */
+ if ((app_part[0] < IRAM_ADDR) ||
+ ((uint8_t *)app_part[0] > IRAM_END))
+ return 1;
+
+ /* if the second word of the application partition doesn't look
+ * like a function from flash (reset vector), enter DFU mode */
+ if (((uint32_t *)app_part[1] < app_part) ||
+ ((uint8_t *)app_part[1] > IFLASH_END))
+ return 1;
+
+ return 0;
+}
/* returns '1' in case we should break any endless loop */
static void check_exec_dbg_cmd(void)
diff --git a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu.h b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu.h
index 4af3e3b..87ac060 100644
--- a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu.h
+++ b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu.h
@@ -110,6 +110,7 @@
uint8_t *data, unsigned int len);
extern int USBDFU_handle_upload(uint8_t altif, unsigned int offset,
uint8_t *data, unsigned int req_len);
+extern int USBDFU_OverrideEnterDFU(void);
/* function to be called at end of EP0 handler during runtime */
void USBDFU_Runtime_RequestHandler(const USBGenericRequest *request);
diff --git a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_driver.c b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_driver.c
index f9e2d8e..10f015b 100644
--- a/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_driver.c
+++ b/firmware/atmel_softpack_libraries/usb/device/dfu/dfu_driver.c
@@ -472,6 +472,14 @@
NVIC_SystemReset();
}
+/* A board can provide a function overriding this, enabling a
+ * board-specific 'boot into DFU' override, like a specific GPIO that
+ * needs to be pulled a certain way. */
+WEAK int USBDFU_OverrideEnterDFU(void)
+{
+ return 0;
+}
+
void USBDCallbacks_RequestReceived(const USBGenericRequest *request)
{
USBDFU_DFU_RequestHandler(request);
diff --git a/firmware/libboard/common/source/board_cstartup_gnu.c b/firmware/libboard/common/source/board_cstartup_gnu.c
index 3d92d2f..ce60b09 100644
--- a/firmware/libboard/common/source/board_cstartup_gnu.c
+++ b/firmware/libboard/common/source/board_cstartup_gnu.c
@@ -157,7 +157,7 @@
/* we are before the text segment has been relocated, so g_dfu is
* not initialized yet */
g_dfu = &_g_dfu;
- if (g_dfu->magic != USB_DFU_MAGIC) {
+ if ((g_dfu->magic != USB_DFU_MAGIC) && !USBDFU_OverrideEnterDFU()) {
BootIntoApp();
/* Infinite loop */
while ( 1 ) ;