linux-kernel - [PATCH 2/2] can: rcar_canfd: Add support for FD-Only mode

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Message-ID: <20251118141840.267652-3-biju.das.jz@bp.renesas.com>
Date: Tue, 18 Nov 2025 14:18:35 +0000
From: Biju <biju.das.au@...il.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>,
	Vincent Mailhol <mailhol@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>
Cc: Biju Das <biju.das.jz@...renesas.com>,
	linux-can@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
	Biju Das <biju.das.au@...il.com>
Subject: [PATCH 2/2] can: rcar_canfd: Add support for FD-Only mode

From: Biju Das <biju.das.jz@...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@...renesas.com>
---
 drivers/net/can/rcar/rcar_canfd.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 05dbdf46dd6f..6dc6bb1efceb 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -444,6 +444,7 @@ struct rcar_canfd_hw_info {
 	unsigned ch_interface_mode:1;	/* Has channel interface mode */
 	unsigned shared_can_regs:1;	/* Has shared classical can registers */
 	unsigned external_clk:1;	/* Has external clock */
+	unsigned has_fd_only_mode:1;	/* Has FD-Only mode */
 };
 
 /* Channel priv data */
@@ -471,6 +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;
@@ -615,6 +617,7 @@ static const struct rcar_canfd_hw_info rcar_gen3_hw_info = {
 	.ch_interface_mode = 0,
 	.shared_can_regs = 0,
 	.external_clk = 1,
+	.has_fd_only_mode = 0,
 };
 
 static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
@@ -632,6 +635,7 @@ static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
 	.ch_interface_mode = 1,
 	.shared_can_regs = 1,
 	.external_clk = 1,
+	.has_fd_only_mode = 1,
 };
 
 static const struct rcar_canfd_hw_info rzg2l_hw_info = {
@@ -649,6 +653,7 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
 	.ch_interface_mode = 0,
 	.shared_can_regs = 0,
 	.external_clk = 1,
+	.has_fd_only_mode = 1,
 };
 
 static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
@@ -666,6 +671,7 @@ static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
 	.ch_interface_mode = 1,
 	.shared_can_regs = 1,
 	.external_clk = 0,
+	.has_fd_only_mode = 1,
 };
 
 /* Helper functions */
@@ -828,12 +834,20 @@ 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);
 		}
 	}
 
@@ -2041,6 +2055,14 @@ 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")) {
+		if (!info->has_fd_only_mode)
+			return dev_err_probe(dev, EOPNOTSUPP,
+					     "fd-only mode not supported\n");
+
+		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),
@@ -2190,7 +2212,7 @@ 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