greybus: loopback: support module-initiated requests

There's no reason we can't support loopback pings or transfers
initiated by the module.  Allow it.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index decaf71..285e44b 100644 (file)
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -242,6 +242,48 @@ static int gb_loopback_ping(struct gb_loopback *gb, struct timeval *tping)
        return retval;
 }
 
+static int gb_loopback_request_recv(u8 type, struct gb_operation *operation)
+{
+       struct gb_connection *connection = operation->connection;
+       struct gb_loopback_transfer_request *request;
+       struct gb_loopback_transfer_response *response;
+       u32 len;
+
+       /* By convention, the AP initiates the version operation */
+       switch (type) {
+       case GB_LOOPBACK_TYPE_PROTOCOL_VERSION:
+               dev_err(&connection->dev,
+                       "module-initiated version operation\n");
+               return -EINVAL;
+       case GB_LOOPBACK_TYPE_PING:
+               return 0;
+       case GB_LOOPBACK_TYPE_TRANSFER:
+               if (operation->request->payload_size < sizeof(*request)) {
+                       dev_err(&connection->dev,
+                               "transfer request too small (%zu < %zu)\n",
+                               operation->request->payload_size,
+                               sizeof(*request));
+                       return -EINVAL; /* -EMSGSIZE */
+               }
+               request = operation->request->payload;
+               len = le32_to_cpu(request->len);
+               if (len) {
+                       if (!gb_operation_response_alloc(operation, len)) {
+                               dev_err(&connection->dev,
+                                       "error allocating response\n");
+                               return -ENOMEM;
+                       }
+                       response = operation->response->payload;
+                       memcpy(response->data, request->data, len);
+               }
+               return 0;
+       default:
+               dev_err(&connection->dev,
+                       "unsupported request: %hhu\n", type);
+               return -EINVAL;
+       }
+}
+
 static void gb_loopback_reset_stats(struct gb_loopback *gb)
 {
        struct gb_loopback_stats reset = {
@@ -397,7 +439,7 @@ static struct gb_protocol loopback_protocol = {
        .minor                  = GB_LOOPBACK_VERSION_MINOR,
        .connection_init        = gb_loopback_connection_init,
        .connection_exit        = gb_loopback_connection_exit,
-       .request_recv           = NULL, /* no incoming requests */
+       .request_recv           = gb_loopback_request_recv,
 };
 
 gb_protocol_driver(&loopback_protocol);