can: mcp25xxfd: add listen-only mode

This commit enables listen-only mode, which works internally like CANFD mode.
Signed-off-by: NKurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20200918172536.2074504-5-mkl@pengutronix.de

drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c

@@ -392,7 +392,8 @@ static int mcp25xxfd_ring_alloc(struct mcp25xxfd_priv *priv)
 	int ram_free, i;
 
 	tef_obj_size = sizeof(struct mcp25xxfd_hw_tef_obj);
-	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
+	/* listen-only mode works like FD mode */
+	if (priv->can.ctrlmode & (CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_FD)) {
 		tx_obj_num = MCP25XXFD_TX_OBJ_NUM_CANFD;
 		tx_obj_size = sizeof(struct mcp25xxfd_hw_tx_obj_canfd);
 		rx_obj_size = sizeof(struct mcp25xxfd_hw_rx_obj_canfd);
@@ -807,7 +808,7 @@ mcp25xxfd_chip_rx_fifo_init_one(const struct mcp25xxfd_priv *priv,
 		MCP25XXFD_REG_FIFOCON_RXOVIE |
 		MCP25XXFD_REG_FIFOCON_TFNRFNIE;
 
-	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
+	if (priv->can.ctrlmode & (CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_FD))
 		fifo_con |= FIELD_PREP(MCP25XXFD_REG_FIFOCON_PLSIZE_MASK,
 				       MCP25XXFD_REG_FIFOCON_PLSIZE_64);
 	else
@@ -857,7 +858,7 @@ static int mcp25xxfd_chip_fifo_init(const struct mcp25xxfd_priv *priv)
 		MCP25XXFD_REG_FIFOCON_TXEN |
 		MCP25XXFD_REG_FIFOCON_TXATIE;
 
-	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
+	if (priv->can.ctrlmode & (CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_FD))
 		val |= FIELD_PREP(MCP25XXFD_REG_FIFOCON_PLSIZE_MASK,
 				  MCP25XXFD_REG_FIFOCON_PLSIZE_64);
 	else
@@ -930,7 +931,9 @@ static u8 mcp25xxfd_get_normal_mode(const struct mcp25xxfd_priv *priv)
 {
 	u8 mode;
 
-	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		mode = MCP25XXFD_REG_CON_MODE_LISTENONLY;
+	else if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
 		mode = MCP25XXFD_REG_CON_MODE_MIXED;
 	else
 		mode = MCP25XXFD_REG_CON_MODE_CAN2_0;
@@ -2792,8 +2795,9 @@ static int mcp25xxfd_probe(struct spi_device *spi)
 	priv->can.do_get_berr_counter = mcp25xxfd_get_berr_counter;
 	priv->can.bittiming_const = &mcp25xxfd_bittiming_const;
 	priv->can.data_bittiming_const = &mcp25xxfd_data_bittiming_const;
-	priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING |
-		CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO;
+	priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
+		CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_FD |
+		CAN_CTRLMODE_FD_NON_ISO;
 	priv->ndev = ndev;
 	priv->spi = spi;
 	priv->rx_int = rx_int;