From: Biju Das <biju.das.jz@bp.renesas.com>

The RZ/{G2L,G3E} and R-Car Gen4 SoCs support additional CAN FD mode called
FD-only mode. In this mode, communication in Classical CAN frame format is
disabled.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v3->v4:
 * No change.
v2->v3:
 * No change.
v1->v2:
 * Dropped has_fd_only_mode variable from the struct rcar_canfd_hw_info
   as it is checked by the dt schema validation.
---
 drivers/net/can/rcar/rcar_canfd.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 7895e1fdea1c..4a653d8978ba 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -472,6 +472,7 @@ struct rcar_canfd_global {
 	unsigned long channels_mask;	/* Enabled channels mask */
 	bool extclk;			/* CANFD or Ext clock */
 	bool fdmode;			/* CAN FD or Classical CAN only mode */
+	bool fd_only_mode;		/* FD-Only mode for CAN-FD */
 	struct reset_control *rstc1;
 	struct reset_control *rstc2;
 	const struct rcar_canfd_hw_info *info;
@@ -829,12 +830,20 @@ static int rcar_canfd_reset_controller(struct rcar_canfd_global *gpriv)
 							 RCANFD_GEN4_FDCFG_FDOE);
 				rcar_canfd_set_bit_reg(&gpriv->fcbase[ch].cfdcfg,
 						       RCANFD_GEN4_FDCFG_CLOE);
+			} else if (gpriv->fd_only_mode) {
+				rcar_canfd_clear_bit_reg(&gpriv->fcbase[ch].cfdcfg,
+							 RCANFD_GEN4_FDCFG_CLOE);
+				rcar_canfd_set_bit_reg(&gpriv->fcbase[ch].cfdcfg,
+						       RCANFD_GEN4_FDCFG_FDOE);
 			} else {
 				rcar_canfd_clear_bit_reg(&gpriv->fcbase[ch].cfdcfg,
 							 RCANFD_GEN4_FDCFG_FDOE);
 				rcar_canfd_clear_bit_reg(&gpriv->fcbase[ch].cfdcfg,
 							 RCANFD_GEN4_FDCFG_CLOE);
 			}
+		} else if (gpriv->fd_only_mode) {
+			rcar_canfd_set_bit_reg(&gpriv->fcbase[ch].cfdcfg,
+					       RCANFD_GEN4_FDCFG_FDOE);
 		}
 	}
 
@@ -2140,6 +2149,9 @@ static int rcar_canfd_probe(struct platform_device *pdev)
 	gpriv->fdmode = fdmode;
 	gpriv->info = info;
 
+	if (of_property_read_bool(dev->of_node, "renesas,fd-only"))
+		gpriv->fd_only_mode = true; /* FD-Only mode for CAN-FD */
+
 	gpriv->rstc1 = devm_reset_control_get_optional_exclusive(dev, "rstp_n");
 	if (IS_ERR(gpriv->rstc1))
 		return dev_err_probe(dev, PTR_ERR(gpriv->rstc1),
@@ -2239,7 +2251,7 @@ static int rcar_canfd_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, gpriv);
 	dev_info(dev, "global operational state (%s clk, %s mode)\n",
 		 gpriv->extclk ? "ext" : "canfd",
-		 gpriv->fdmode ? "fd" : "classical");
+		 gpriv->fdmode ? (gpriv->fd_only_mode ? "fd-only" : "fd") : "classical");
 	return 0;
 
 fail_channel:
-- 
2.43.0