broadband-modem: if the generic CNMI request fails, try a Qualcomm-compatible one

This is the port to git master of the following commit:

commit 1d9164ec90788d1be134482ff88c501e3c5d623c
Author: Dan Williams <dcbw@redhat.com>
Date:   Mon Aug 27 18:20:33 2012 -0500

    gsm: if the generic CNMI request fails, try a Qualcomm-compatible one

    Many devices based on Qualcomm chipsets don't support a <ds> value
    of '1', despite saying they do in the AT+CNMI=? response.  But they
    do accept '2'.  Since we're not doing much with delivery status
    reports yet, if we get a CME 303 (not supported) error when setting
    the message indication parameters via CNMI, fall back to the
    Qualcomm-compatible CNMI parameters.

    If we don't do this, we don't get SMS indications on these devices,
    because the original CNMI failed.

    Tested on Huawei E1550, Huawei E160G, ZTE MF622, and Novatel XU870.

src/mm-broadband-modem.c

@@ -4410,20 +4410,67 @@ modem_messaging_enable_unsolicited_events_finish (MMIfaceModemMessaging *self,
                                                   GAsyncResult *res,
                                                   GError **error)
 {
-    return !!mm_base_modem_at_command_finish (MM_BASE_MODEM (self), res, error);
+    GError *inner_error = NULL;
+
+    mm_base_modem_at_sequence_finish (MM_BASE_MODEM (self), res, NULL, &inner_error);
+    if (inner_error) {
+        g_propagate_error (error, inner_error);
+        return FALSE;
+    }
+
+    return TRUE;
 }
 
+static gboolean
+cnmi_response_processor (MMBaseModem *self,
+                         gpointer none,
+                         const gchar *command,
+                         const gchar *response,
+                         gboolean last_command,
+                         const GError *error,
+                         GVariant **result,
+                         GError **result_error)
+{
+    if (error) {
+        /* If we get a not-supported error and we're not in the last command, we
+         * won't set 'result_error', so we'll keep on the sequence */
+        if (!g_error_matches (error, MM_MESSAGE_ERROR, MM_MESSAGE_ERROR_NOT_SUPPORTED) ||
+            last_command)
+            *result_error = g_error_copy (error);
+
+        return FALSE;
+    }
+
+    *result = NULL;
+    return TRUE;
+}
+
+/*
+ * Many devices based on Qualcomm chipsets don't support a <ds> value
+ * of '1', despite saying they do in the AT+CNMI=? response.  But they
+ * do accept '2'.  Since we're not doing much with delivery status
+ * reports yet, if we get a CME 303 (not supported) error when setting
+ * the message indication parameters via CNMI, fall back to the
+ * Qualcomm-compatible CNMI parameters.
+ */
+static const MMBaseModemAtCommand cnmi_sequence[] = {
+    { "+CNMI=2,1,2,1,0", 3, TRUE, cnmi_response_processor },
+    { "+CNMI=2,1,2,2,0", 3, TRUE, cnmi_response_processor },
+    { NULL }
+};
+
 static void
 modem_messaging_enable_unsolicited_events (MMIfaceModemMessaging *self,
                                            GAsyncReadyCallback callback,
                                            gpointer user_data)
 {
-    mm_base_modem_at_command (MM_BASE_MODEM (self),
-                              "+CNMI=2,1,2,1,0",
-                              3,
-                              FALSE,
-                              callback,
-                              user_data);
+    mm_base_modem_at_sequence (
+        MM_BASE_MODEM (self),
+        cnmi_sequence,
+        NULL, /* response_processor_context */
+        NULL, /* response_processor_context_free */
+        callback,
+        user_data);
 }
 
 /*****************************************************************************/