Support resetting Picoprobe board using identical endpoints to RP2040 USB_RESET interface

Author: Tom Mloduchowski

include/board_pico_config.h

@@ -49,4 +49,7 @@
 
 #define PROBE_PRODUCT_STRING "Picoprobe (CMSIS-DAP)"
 
+// Host Reset Config
+#define PICOPROBE_RESET_CAPABLE 1
+
 #endif

src/main.c

@@ -42,6 +42,13 @@
 #include "tusb_edpt_handler.h"
 #include "DAP.h"
 
+#include "usb_reset_interface.h"
+#include "pico/bootrom.h"
+#include "hardware/watchdog.h"
+
+
+
+
 // UART0 for Picoprobe debug
 // UART1 for picoprobe to target device
 
@@ -153,6 +160,20 @@ bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_requ
   // nothing to with DATA & ACK stage
   if (stage != CONTROL_STAGE_SETUP) return true;
 
+#if PICOPROBE_RESET_CAPABLE
+  if (request->wIndex == 3) {
+    if (request->bRequest == RESET_REQUEST_BOOTSEL) {
+      reset_usb_boot(0, (request->wValue & 0x7f) | 0);
+      return true;
+    }
+    if (request->bRequest == RESET_REQUEST_FLASH) {
+      watchdog_reboot(0, 0, 100);
+      return true;
+    }
+    return false;
+  }
+#endif
+
   switch (request->bmRequestType_bit.type)
   {
     case TUSB_REQ_TYPE_VENDOR:

src/tusb_config.h

@@ -26,6 +26,8 @@
 #ifndef _TUSB_CONFIG_H_
 #define _TUSB_CONFIG_H_
 
+#include "picoprobe_config.h"
+
 #ifdef __cplusplus
  extern "C" {
 #endif
@@ -66,7 +68,12 @@
 #define CFG_TUD_CDC             1
 #define CFG_TUD_MSC             0
 #define CFG_TUD_MIDI            0
+
+#if PICOPROBE_RESET_CAPABLE
+#define CFG_TUD_VENDOR          2
+#else
 #define CFG_TUD_VENDOR          1
+#endif
 
 /*
  * TX bufsize (actually UART RX) is oversized because the Windows CDC-ACM

src/usb_descriptors.c

@@ -29,6 +29,8 @@
 #include "get_serial.h"
 #include "picoprobe_config.h"
 
+#include "usb_reset_interface.h"
+
 //--------------------------------------------------------------------+
 // Device Descriptors
 //--------------------------------------------------------------------+
@@ -71,6 +73,9 @@ enum
   ITF_NUM_PROBE, // Old versions of Keil MDK only look at interface 0
   ITF_NUM_CDC_COM,
   ITF_NUM_CDC_DATA,
+#if PICOPROBE_RESET_CAPABLE
+  ITF_NUM_RPI_RESET,
+#endif
   ITF_NUM_TOTAL
 };
 
@@ -80,11 +85,24 @@ enum
 #define PROBE_OUT_EP_NUM 0x04
 #define PROBE_IN_EP_NUM 0x85
 
+
+#if PICOPROBE_RESET_CAPABLE
+#define TUD_RPI_RESET_DESCRIPTOR_LEN 9
+
+#define TUD_RPI_RESET_DESCRIPTOR(_itfnum, _stridx) \
+  /* Interface */\
+  9, TUSB_DESC_INTERFACE, _itfnum, 0, 0, TUSB_CLASS_VENDOR_SPECIFIC, RESET_INTERFACE_SUBCLASS, RESET_INTERFACE_PROTOCOL, _stridx
+#endif
+
 #if (PICOPROBE_DEBUG_PROTOCOL == PROTO_DAP_V1)
 #define CONFIG_TOTAL_LEN  (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN + TUD_HID_INOUT_DESC_LEN)
 #else
+#if PICOPROBE_RESET_CAPABLE
+#define CONFIG_TOTAL_LEN  (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN + TUD_VENDOR_DESC_LEN + TUD_RPI_RESET_DESCRIPTOR_LEN)
+#else
 #define CONFIG_TOTAL_LEN  (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN + TUD_VENDOR_DESC_LEN)
 #endif
+#endif
 
 static uint8_t const desc_hid_report[] =
 {
@@ -113,6 +131,10 @@ uint8_t const desc_configuration[] =
 #endif
   // Interface 1 + 2
   TUD_CDC_DESCRIPTOR(ITF_NUM_CDC_COM, 6, CDC_NOTIFICATION_EP_NUM, 64, CDC_DATA_OUT_EP_NUM, CDC_DATA_IN_EP_NUM, 64),
+#if PICOPROBE_RESET_CAPABLE
+  // Picotool compatible reset descriptor.
+  TUD_RPI_RESET_DESCRIPTOR(ITF_NUM_RPI_RESET, 7),
+#endif
 };
 
 // Invoked when received GET CONFIGURATION DESCRIPTOR
@@ -138,6 +160,9 @@ char const* string_desc_arr [] =
   "CMSIS-DAP v1 Interface", // 4: Interface descriptor for HID transport
   "CMSIS-DAP v2 Interface", // 5: Interface descriptor for Bulk transport
   "CDC-ACM UART Interface", // 6: Interface descriptor for CDC
+#if PICOPROBE_RESET_CAPABLE
+  "Reset", // 7: RPI Reset.
+#endif
 };
 
 static uint16_t _desc_str[32];

src/usb_reset_interface.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _PICO_USB_RESET_INTERFACE_H
+#define _PICO_USB_RESET_INTERFACE_H
+
+/** \file usb_reset_interface.h
+ *  \defgroup pico_usb_reset_interface pico_usb_reset_interface
+ *
+ * Definition for the reset interface that may be exposed by the pico_stdio_usb library
+ */
+
+// VENDOR sub-class for the reset interface
+#define RESET_INTERFACE_SUBCLASS 0x00
+// VENDOR protocol for the reset interface
+#define RESET_INTERFACE_PROTOCOL 0x01
+
+// CONTROL requests:
+
+// reset to BOOTSEL
+#define RESET_REQUEST_BOOTSEL 0x01
+// regular flash boot
+#define RESET_REQUEST_FLASH 0x02
+
+#endif