ublox: Add CDC-ECM support for SARA/LISA-U2xx

The SARA-U2xx and LISA-U20x require the PDP context to be activated via
+UCEDATA instead of +CGACT=1 when using the CDC-ECM USB profile.
Furthermore, they expect the DHCP discover packet from the TE while the
command is running, i.e. while the modem has not replied yet. In order
to achieve that, the bearer is marked as connected as soon as the
command is issued. This makes the NetworkManager start the DHCP process.
If the modem replies with an error, the bearer will be marked
disconnected later on.

Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>

plugins/ublox/mm-broadband-bearer-ublox.c

@@ -55,6 +55,7 @@ struct _MMBroadbandBearerUbloxPrivate {
     MMUbloxNetworkingMode    mode;
     MMUbloxBearerAllowedAuth allowed_auths;
     FeatureSupport           statistics;
+    FeatureSupport           cedata;
 };
 
 /*****************************************************************************/
@@ -327,6 +328,25 @@ dial_3gpp_finish (MMBroadbandBearer  *self,
     return MM_PORT (g_task_propagate_pointer (G_TASK (res), error));
 }
 
+static void
+cedata_activate_ready (MMBaseModem            *modem,
+                       GAsyncResult           *res,
+                       MMBroadbandBearerUblox *self)
+{
+    const gchar *response;
+    GError      *error = NULL;
+
+    response = mm_base_modem_at_command_finish (modem, res, &error);
+    if (!response) {
+        mm_warn ("ECM data connection attempt failed: %s", error->message);
+        mm_base_bearer_report_connection_status (MM_BASE_BEARER (self),
+                                                 MM_BEARER_CONNECTION_STATUS_DISCONNECTED);
+        g_error_free (error);
+    }
+    /* we received a full bearer object reference */
+    g_object_unref (self);
+}
+
 static void
 cgact_activate_ready (MMBaseModem  *modem,
                       GAsyncResult *res,
@@ -354,17 +374,82 @@ activate_3gpp (GTask *task)
 
     ctx = (CommonConnectContext *) g_task_get_task_data (task);
 
-    cmd = g_strdup_printf ("+CGACT=1,%u", ctx->cid);
+    if (ctx->self->priv->profile == MM_UBLOX_USB_PROFILE_ECM &&
-    mm_dbg ("activating PDP context #%u...", ctx->cid);
+        ctx->self->priv->cedata == FEATURE_SUPPORTED) {
-    mm_base_modem_at_command (MM_BASE_MODEM (ctx->modem),
+        /* SARA-U2xx and LISA-U20x only expose one CDC-ECM interface. Hence,
-                              cmd,
+           the fixed 0 as the interface index here. When we see modems with
-                              120,
+           multiple interfaces, this needs to be revisited. */
-                              FALSE,
+        cmd = g_strdup_printf ("+UCEDATA=%u,0", ctx->cid);
-                              (GAsyncReadyCallback) cgact_activate_ready,
+        mm_dbg ("establishing ECM data connection for PDP context #%u...", ctx->cid);
-                              task);
+        mm_base_modem_at_command (MM_BASE_MODEM (ctx->modem),
+                                  cmd,
+                                  180,
+                                  FALSE,
+                                  (GAsyncReadyCallback) cedata_activate_ready,
+                                  g_object_ref (ctx->self));
+        /* We'll mark the task done here since the modem expects the DHCP
+           discover packet while +UCEDATA runs. If the command fails, we'll
+           mark the bearer disconnected later in the callback. */
+        g_task_return_pointer (task, g_object_ref (ctx->data), g_object_unref);
+        g_object_unref (task);
+   } else {
+        cmd = g_strdup_printf ("+CGACT=1,%u", ctx->cid);
+        mm_dbg ("activating PDP context #%u...", ctx->cid);
+        mm_base_modem_at_command (MM_BASE_MODEM (ctx->modem),
+                                  cmd,
+                                  120,
+                                  FALSE,
+                                  (GAsyncReadyCallback) cgact_activate_ready,
+                                  task);
+    }
     g_free (cmd);
 }
 
+static void
+test_cedata_ready (MMBaseModem  *modem,
+                   GAsyncResult *res,
+                   GTask        *task)
+{
+    CommonConnectContext *ctx;
+    const gchar         *response;
+
+    ctx = (CommonConnectContext *) g_task_get_task_data (task);
+
+    response = mm_base_modem_at_command_finish (modem, res, NULL);
+    if (response)
+        ctx->self->priv->cedata = FEATURE_SUPPORTED;
+    else
+        ctx->self->priv->cedata = FEATURE_UNSUPPORTED;
+    mm_dbg ("u-blox: +UCEDATA command%s available",
+        (ctx->self->priv->cedata == FEATURE_SUPPORTED) ? "" : " not");
+
+    activate_3gpp (task);
+}
+
+static void
+test_cedata (GTask *task)
+{
+    CommonConnectContext *ctx;
+
+    ctx = (CommonConnectContext *) g_task_get_task_data (task);
+
+    /* We don't need to test for +UCEDATA if we're not using CDC-ECM or if we
+       have tested before. Instead, we jump right to the activation. */
+    if (ctx->self->priv->profile != MM_UBLOX_USB_PROFILE_ECM ||
+        ctx->self->priv->cedata != FEATURE_SUPPORT_UNKNOWN) {
+        activate_3gpp (task);
+        return;
+    }
+
+    mm_dbg ("u-blox: checking availability of +UCEDATA command...");
+    mm_base_modem_at_command (MM_BASE_MODEM (ctx->modem),
+                              "+UCEDATA=?",
+                              3,
+                              TRUE, /* allow_cached */
+                              (GAsyncReadyCallback) test_cedata_ready,
+                              task);
+}
+
 static void
 uauthreq_ready (MMBaseModem  *modem,
                 GAsyncResult *res,
@@ -388,7 +473,7 @@ uauthreq_ready (MMBaseModem  *modem,
         g_error_free (error);
     }
 
-    activate_3gpp (task);
+    test_cedata (task);
 }
 
 static void
@@ -502,10 +587,10 @@ out:
             g_object_unref (task);
             return;
         }
-        /* Otherwise, ignore and jump to activate_3gpp directly as no auth setup
+        /* Otherwise, ignore and jump to test_cedata directly as no auth setup
          * is needed */
         g_error_free (error);
-        activate_3gpp (task);
+        test_cedata (task);
         return;
     }
 
@@ -879,6 +964,7 @@ mm_broadband_bearer_ublox_init (MMBroadbandBearerUblox *self)
     self->priv->mode          = MM_UBLOX_NETWORKING_MODE_UNKNOWN;
     self->priv->allowed_auths = MM_UBLOX_BEARER_ALLOWED_AUTH_UNKNOWN;
     self->priv->statistics    = FEATURE_SUPPORT_UNKNOWN;
+    self->priv->cedata        = FEATURE_SUPPORT_UNKNOWN;
 }
 
 static void