From c0fc095500ba5cded6709df47e9ccbcb9b75ac48 Mon Sep 17 00:00:00 2001
From: Marius Greuel <greuelm@mgtek.com>
Date: Tue, 6 Oct 2020 20:36:52 +0200
Subject: [PATCH] Implement ftdi_set_interface for avrftdi

---
 external/libftdi1/src/ftdi.cpp | 40 +++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/external/libftdi1/src/ftdi.cpp b/external/libftdi1/src/ftdi.cpp
index 5739ba17..e3472252 100644
--- a/external/libftdi1/src/ftdi.cpp
+++ b/external/libftdi1/src/ftdi.cpp
@@ -46,6 +46,7 @@ static ftdi_chip_type MapChipType(ULONG type)
         return TYPE_AM;
     }
 }
+
 static int SetError(struct ftdi_context* ftdi, int result, const char* error_str)
 {
     if (ftdi != nullptr)
@@ -82,6 +83,42 @@ void ftdi_free(struct ftdi_context* ftdi)
 
 int ftdi_set_interface(struct ftdi_context* ftdi, enum ftdi_interface interface)
 {
+    if (ftdi == nullptr)
+    {
+        return SetError(ftdi, -2, "USB device unavailable");
+    }
+
+    if (ftdi->usb_dev != nullptr)
+    {
+        if (ftdi->index != (interface != INTERFACE_ANY ? interface : INTERFACE_A))
+        {
+            return SetError(ftdi, -3, "Interface can not be changed on an already open device");
+        }
+    }
+
+    switch (interface)
+    {
+    case INTERFACE_ANY:
+    case INTERFACE_A:
+        ftdi->interface = 0;
+        ftdi->index = INTERFACE_A;
+        break;
+    case INTERFACE_B:
+        ftdi->interface = 1;
+        ftdi->index = INTERFACE_B;
+        break;
+    case INTERFACE_C:
+        ftdi->interface = 2;
+        ftdi->index = INTERFACE_C;
+        break;
+    case INTERFACE_D:
+        ftdi->interface = 3;
+        ftdi->index = INTERFACE_D;
+        break;
+    default:
+        return SetError(ftdi, -1, "Unknown interface");
+    }
+
     return 0;
 }
 
@@ -93,7 +130,7 @@ int ftdi_init(struct ftdi_context* ftdi)
 
 void ftdi_deinit(struct ftdi_context* ftdi)
 {
-    if (ftdi->usb_dev != nullptr)
+    if (ftdi != nullptr && ftdi->usb_dev != nullptr)
     {
         std::unique_ptr<FtdiDevice> device(reinterpret_cast<FtdiDevice*>(ftdi->usb_dev));
         ftdi->usb_dev = nullptr;
@@ -145,6 +182,7 @@ int ftdi_usb_open_desc_index(struct ftdi_context* ftdi, int vendor, int product,
             return SetError(ftdi, -3, "failed to open device");
         }
 
+        device->ResetDevice();
         device->SetEventNotification(FT_EVENT_RXCHAR);
 
         ftdi->type = MapChipType(info.Type);