usb_canbus: Initial support for USB to CAN bridge mode

Support a USB interface that shows up as a canbus adapter to linux.
Route both local and real canbus packets over that interface.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/generic/canserial.c b/src/generic/canserial.c
index ba0ec461..34f0ce65 100644
--- a/src/generic/canserial.c
+++ b/src/generic/canserial.c
@@ -224,7 +224,7 @@ canserial_notify_rx(void)
 DECL_CONSTANT("RECEIVE_WINDOW", ARRAY_SIZE(CanData.receive_buf));
 
 // Handle incoming data (called from IRQ handler)
-void
+int
 canserial_process_data(struct canbus_msg *msg)
 {
     uint32_t id = msg->id;
@@ -233,7 +233,7 @@ canserial_process_data(struct canbus_msg *msg)
         int rpos = CanData.receive_pos;
         uint32_t len = CANMSG_DATA_LEN(msg);
         if (len > sizeof(CanData.receive_buf) - rpos)
-            len = sizeof(CanData.receive_buf) - rpos;
+            return -1;
         memcpy(&CanData.receive_buf[rpos], msg->data, len);
         CanData.receive_pos = rpos + len;
         canserial_notify_rx();
@@ -243,12 +243,13 @@ canserial_process_data(struct canbus_msg *msg)
         uint32_t pushp = CanData.admin_push_pos;
         if (pushp >= CanData.admin_pull_pos + ARRAY_SIZE(CanData.admin_queue))
             // No space - drop message
-            return;
+            return -1;
         uint32_t pos = pushp % ARRAY_SIZE(CanData.admin_queue);
         memcpy(&CanData.admin_queue[pos], msg, sizeof(*msg));
         CanData.admin_push_pos = pushp + 1;
         canserial_notify_rx();
     }
+    return 0;
 }
 
 // Remove from the receive buffer the given number of bytes