can: mcp251xfd: add len8_dlc support

This patch adds support for the Classical CAN raw DLC functionality to send and
receive DLC values from 9 ... 15 to the mcp251xfd driver.

Link: https://lore.kernel.org/r/20210114153448.1506901-6-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c

@@ -1439,6 +1439,7 @@ mcp251xfd_hw_rx_obj_to_skb(const struct mcp251xfd_priv *priv,
 			   struct sk_buff *skb)
 {
 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+	u8 dlc;
 
 	if (hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_IDE) {
 		u32 sid, eid;
@@ -1454,9 +1455,10 @@ mcp251xfd_hw_rx_obj_to_skb(const struct mcp251xfd_priv *priv,
 					hw_rx_obj->id);
 	}
 
+	dlc = FIELD_GET(MCP251XFD_OBJ_FLAGS_DLC, hw_rx_obj->flags);
+
 	/* CANFD */
 	if (hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_FDF) {
-		u8 dlc;
 
 		if (hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_ESI)
 			cfd->flags |= CANFD_ESI;
@@ -1464,14 +1466,13 @@ mcp251xfd_hw_rx_obj_to_skb(const struct mcp251xfd_priv *priv,
 		if (hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_BRS)
 			cfd->flags |= CANFD_BRS;
 
-		dlc = FIELD_GET(MCP251XFD_OBJ_FLAGS_DLC, hw_rx_obj->flags);
 		cfd->len = can_fd_dlc2len(dlc);
 	} else {
 		if (hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_RTR)
 			cfd->can_id |= CAN_RTR_FLAG;
 
-		cfd->len = can_cc_dlc2len(FIELD_GET(MCP251XFD_OBJ_FLAGS_DLC,
-						 hw_rx_obj->flags));
+		can_frame_set_cc_len((struct can_frame *)cfd, dlc,
+				     priv->can.ctrlmode);
 	}
 
 	if (!(hw_rx_obj->flags & MCP251XFD_OBJ_FLAGS_RTR))
@@ -2325,9 +2326,7 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv,
 	 * harm, only the lower 7 bits will be transferred into the
 	 * TEF object.
 	 */
-	dlc = can_fd_len2dlc(cfd->len);
-	flags |= FIELD_PREP(MCP251XFD_OBJ_FLAGS_SEQ_MCP2518FD_MASK, seq) |
-		FIELD_PREP(MCP251XFD_OBJ_FLAGS_DLC, dlc);
+	flags |= FIELD_PREP(MCP251XFD_OBJ_FLAGS_SEQ_MCP2518FD_MASK, seq);
 
 	if (cfd->can_id & CAN_RTR_FLAG)
 		flags |= MCP251XFD_OBJ_FLAGS_RTR;
@@ -2343,8 +2342,15 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv,
 
 		if (cfd->flags & CANFD_BRS)
 			flags |= MCP251XFD_OBJ_FLAGS_BRS;
+
+		dlc = can_fd_len2dlc(cfd->len);
+	} else {
+		dlc = can_get_cc_dlc((struct can_frame *)cfd,
+				     priv->can.ctrlmode);
 	}
 
+	flags |= FIELD_PREP(MCP251XFD_OBJ_FLAGS_DLC, dlc);
+
 	load_buf = &tx_obj->buf;
 	if (priv->devtype_data.quirks & MCP251XFD_QUIRK_CRC_TX)
 		hw_tx_obj = &load_buf->crc.hw_tx_obj;
@@ -2896,7 +2902,8 @@ static int mcp251xfd_probe(struct spi_device *spi)
 	priv->can.data_bittiming_const = &mcp251xfd_data_bittiming_const;
 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
 		CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_BERR_REPORTING |
-		CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO;
+		CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO |
+		CAN_CTRLMODE_CC_LEN8_DLC;
 	priv->ndev = ndev;
 	priv->spi = spi;
 	priv->rx_int = rx_int;