usb_cdc: Change callback return values to allow error return

Require a return value from:
	CDC_SET_COMM_FEATURE_CALLBACK()
	CDC_CLEAR_COMM_FEATURE_CALLBACK()
	CDC_SET_LINE_CODING_CALLBACK()

This allows the application to return -1 so a STALL can be sent to the
host.

Author: signal11

apps/cdc_acm/main.c

@@ -280,18 +280,18 @@ int16_t app_get_encapsulated_response(uint8_t interface,
 	return -1;
 }
 
-void app_set_comm_feature_callback(uint8_t interface,
+int8_t app_set_comm_feature_callback(uint8_t interface,
                                      bool idle_setting,
                                      bool data_multiplexed_state)
 {
-
+	return -1;
 }
 
-void app_clear_comm_feature_callback(uint8_t interface,
+int8_t app_clear_comm_feature_callback(uint8_t interface,
                                        bool idle_setting,
                                        bool data_multiplexed_state)
 {
-
+	return -1;
 }
 
 int8_t app_get_comm_feature_callback(uint8_t interface,
@@ -301,10 +301,10 @@ int8_t app_get_comm_feature_callback(uint8_t interface,
 	return -1;
 }
 
-void app_set_line_coding_callback(uint8_t interface,
+int8_t app_set_line_coding_callback(uint8_t interface,
                                     const struct cdc_line_coding *coding)
 {
-
+	return -1;
 }
 
 int8_t app_get_line_coding_callback(uint8_t interface,

usb/include/usb_cdc.h

@@ -356,8 +356,12 @@ extern int16_t CDC_GET_ENCAPSULATED_RESPONSE_CALLBACK(uint8_t interface,
  *                       the idle setting.
  * @param data_multiplexed_state  Whether to set the data multiplexed
  *                                state. True = clear the multiplexed state.
+ *
+ * @returns
+ *   Return 0 if the request can be handled or -1 if it cannot. Returning -1
+ *   will cause STALL to be returned to the host.
  */
-extern void CDC_SET_COMM_FEATURE_CALLBACK(uint8_t interface,
+extern int8_t CDC_SET_COMM_FEATURE_CALLBACK(uint8_t interface,
                                             bool idle_setting,
                                             bool data_multiplexed_state);
 #endif
@@ -376,10 +380,14 @@ extern void CDC_SET_COMM_FEATURE_CALLBACK(uint8_t interface,
  *                       the idle setting.
  * @param data_multiplexed_state  Whether to clear the data multiplexed
  *                                state. True = clear the multiplexed state.
+ *
+ * @returns
+ *   Return 0 if the request can be handled or -1 if it cannot. Returning -1
+ *   will cause STALL to be returned to the host.
  */
-extern void CDC_CLEAR_COMM_FEATURE_CALLBACK(uint8_t interface,
-                                            bool idle_setting,
-                                            bool data_multiplexed_state);
+extern int8_t CDC_CLEAR_COMM_FEATURE_CALLBACK(uint8_t interface,
+                                              bool idle_setting,
+                                              bool data_multiplexed_state);
 #endif
 
 #ifdef CDC_GET_COMM_FEATURE_CALLBACK
@@ -416,8 +424,11 @@ extern int8_t CDC_GET_COMM_FEATURE_CALLBACK(
  * @param interface      The interface for which the command is intended
  * @param coding         The new line coding set by the host
  *
+ * @returns
+ *   Return 0 if the request can be handled or -1 if it cannot. Returning -1
+ *   will cause STALL to be returned to the host.
  */
-extern void CDC_SET_LINE_CODING_CALLBACK(uint8_t interface,
+extern int8_t CDC_SET_LINE_CODING_CALLBACK(uint8_t interface,
                                          const struct cdc_line_coding *coding);
 #endif
 

usb/src/usb_cdc.c

@@ -92,15 +92,15 @@ static int8_t set_or_clear_comm_feature_callback(bool transfer_ok, void *context
 	bool data_multiplexed_state = (transfer_data.comm_feature & 2) != 0;
 
 	if (set_or_clear_request == CDC_SET_COMM_FEATURE) {
-		CDC_SET_COMM_FEATURE_CALLBACK(transfer_interface,
-		                              idle_setting,
-		                              data_multiplexed_state);
+		return CDC_SET_COMM_FEATURE_CALLBACK(transfer_interface,
+		                                     idle_setting,
+		                                     data_multiplexed_state);
 	}
 	else {
 		/* request == CDC_CLEAR_COMM_FEATURE */
-		CDC_CLEAR_COMM_FEATURE_CALLBACK(transfer_interface,
-		                                idle_setting,
-		                                data_multiplexed_state);
+		return CDC_CLEAR_COMM_FEATURE_CALLBACK(transfer_interface,
+		                                       idle_setting,
+		                                       data_multiplexed_state);
 	}
 	return 0;
 }
@@ -111,9 +111,8 @@ static int8_t set_line_coding(bool transfer_ok, void *context) {
 	if (!transfer_ok)
 		return -1;
 
-	CDC_SET_LINE_CODING_CALLBACK(transfer_interface,
-	                             &transfer_data.line_coding);
-	return 0;
+	return CDC_SET_LINE_CODING_CALLBACK(transfer_interface,
+	                                    &transfer_data.line_coding);
 }
 #endif