greybus: uart: Add support for UART error signals

After reviewing the UART specification for greybus break, parity, framing
and over-run errors were moved to the receive-data message. This patch
implements that specification change in the UART protocol driver. Matching
code in gbsim has been tested with this change.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/uart.c

@@ -70,28 +70,34 @@ static atomic_t reference_count = ATOMIC_INIT(0);
 /* Define get_version() routine */
 define_get_version(gb_tty, UART);
 
-static int gb_uart_request_recv(u8 type, struct gb_operation *op)
+static int gb_uart_receive_data(struct gb_tty *gb_tty,
+				struct gb_connection *connection,
+				struct gb_uart_recv_data_request *receive_data)
 {
-	struct gb_connection *connection = op->connection;
-	struct gb_tty *gb_tty = connection->private;
-	struct gb_message *request = op->request;
-	struct gb_uart_recv_data_request *receive_data;
-	struct gb_uart_serial_state_request *serial_state;
 	struct tty_port *port = &gb_tty->port;
 	u16 recv_data_size;
 	int count;
-	int ret = 0;
+	unsigned long tty_flags = TTY_NORMAL;
 
-	switch (type) {
-	case GB_UART_TYPE_RECEIVE_DATA:
-		receive_data = request->payload;
 	count = gb_tty->buffer_payload_max - sizeof(*receive_data);
 	recv_data_size = le16_to_cpu(receive_data->size);
 	if (!recv_data_size || recv_data_size > count)
 		return -EINVAL;
 
-		count = tty_insert_flip_string(port, receive_data->data,
-					       recv_data_size);
+	if (receive_data->flags) {
+		if (receive_data->flags & GB_UART_RECV_FLAG_BREAK)
+			tty_flags = TTY_BREAK;
+		else if (receive_data->flags & GB_UART_RECV_FLAG_PARITY)
+			tty_flags = TTY_PARITY;
+		else if (receive_data->flags & GB_UART_RECV_FLAG_FRAMING)
+			tty_flags = TTY_FRAME;
+
+		/* overrun is special, not associated with a char */
+		if (receive_data->flags & GB_UART_RECV_FLAG_OVERRUN)
+			tty_insert_flip_char(port, 0, TTY_OVERRUN);
+	}
+	count = tty_insert_flip_string_fixed_flag(port, receive_data->data,
+						  tty_flags, recv_data_size);
 	if (count != recv_data_size) {
 		dev_err(&connection->dev,
 			"UART: RX 0x%08x bytes only wrote 0x%08x\n",
@@ -99,6 +105,21 @@ static int gb_uart_request_recv(u8 type, struct gb_operation *op)
 	}
 	if (count)
 		tty_flip_buffer_push(port);
+	return 0;
+}
+
+static int gb_uart_request_recv(u8 type, struct gb_operation *op)
+{
+	struct gb_connection *connection = op->connection;
+	struct gb_tty *gb_tty = connection->private;
+	struct gb_message *request = op->request;
+	struct gb_uart_serial_state_request *serial_state;
+	int ret = 0;
+
+	switch (type) {
+	case GB_UART_TYPE_RECEIVE_DATA:
+		ret = gb_uart_receive_data(gb_tty, connection,
+					   request->payload);
 		break;
 	case GB_UART_TYPE_SERIAL_STATE:
 		serial_state = request->payload;