linux-kernel - [PATCH 19/21] can: calc_bittiming: make can_calc

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Message-Id: <20250903-canxl-netlink-prep-v1-19-904bd6037cd9@kernel.org>
Date: Wed, 03 Sep 2025 17:50:18 +0900
From: Vincent Mailhol <mailhol@...nel.org>
To: Marc Kleine-Budde <mkl@...gutronix.de>, 
 Oliver Hartkopp <socketcan@...tkopp.net>
Cc: Vincent Mailhol <mailhol@...nel.org>, 
 Stéphane Grosjean <stephane.grosjean@...-networks.com>, 
 Robert Nawrath <mbro1689@...il.com>, Minh Le <minh.le.aj@...esas.com>, 
 Duy Nguyen <duy.nguyen.rh@...esas.com>, linux-can@...r.kernel.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH 19/21] can: calc_bittiming: make can_calc_tdco() FD
 agnostic

can_calc_tdco() uses the CAN_CTRLMODE_FD_TDC_MASK and
CAN_CTRLMODE_TDC_AUTO macros making it specific to CAN FD. Add the tdc
mask to the function parameter list. The value of the tdc auto flag
can then be derived from that mask and stored in a local variable.
This way, the function becomes CAN FD agnostic and can be reused later
on for the CAN XL TDC.

Signed-off-by: Vincent Mailhol <mailhol@...nel.org>
---
Changelog:

  RFC -> v1:

   - new patch. I overlooked this in the RFC and the CAN XL's TDC was
     broken because of that.
---
 drivers/net/can/dev/calc_bittiming.c | 10 ++++++----
 drivers/net/can/dev/netlink.c        |  2 +-
 include/linux/can/bittiming.h        |  4 ++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_bittiming.c
index a94bd67c670c4801344e1fed6372d0182c46271f..394d6974f48151230510d7f43c80d75e1429dd37 100644
--- a/drivers/net/can/dev/calc_bittiming.c
+++ b/drivers/net/can/dev/calc_bittiming.c
@@ -173,13 +173,15 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 
 void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		   const struct can_bittiming *dbt,
-		   u32 *ctrlmode, u32 ctrlmode_supported)
+		   u32 tdc_mask, u32 *ctrlmode, u32 ctrlmode_supported)
 
 {
-	if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
+	u32 tdc_auto = tdc_mask & CAN_CTRLMODE_TDC_AUTO_MASK;
+
+	if (!tdc_const || !(ctrlmode_supported & tdc_auto))
 		return;
 
-	*ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
+	*ctrlmode &= ~tdc_mask;
 
 	/* As specified in ISO 11898-1 section 11.3.3 "Transmitter
 	 * delay compensation" (TDC) is only applicable if data BRP is
@@ -193,6 +195,6 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		if (sample_point_in_tc < tdc_const->tdco_min)
 			return;
 		tdc->tdco = min(sample_point_in_tc, tdc_const->tdco_max);
-		*ctrlmode |= CAN_CTRLMODE_TDC_AUTO;
+		*ctrlmode |= tdc_auto;
 	}
 }
diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 2784cacd7adf5e69f24c110e749a651b188f69f4..d1c54c7dd333d229f03fc653d61a21a48f8c8865 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -334,7 +334,7 @@ static int can_dbt_changelink(struct net_device *dev, struct nlattr *data[],
 		 * do calculation
 		 */
 		can_calc_tdco(&dbt_params->tdc, dbt_params->tdc_const, &dbt,
-			      &priv->ctrlmode, priv->ctrlmode_supported);
+			      tdc_mask, &priv->ctrlmode, priv->ctrlmode_supported);
 	} /* else: both CAN_CTRLMODE_TDC_{AUTO,MANUAL} are explicitly
 	   * turned off. TDC is disabled: do nothing
 	   */
diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h
index 71f839c3f0325b2a496a4bc447044a4853541338..d30816dd93c7082c774ca4c01ee42465cd042ca0 100644
--- a/include/linux/can/bittiming.h
+++ b/include/linux/can/bittiming.h
@@ -135,7 +135,7 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 
 void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		   const struct can_bittiming *dbt,
-		   u32 *ctrlmode, u32 ctrlmode_supported);
+		   u32 tdc_mask, u32 *ctrlmode, u32 ctrlmode_supported);
 #else /* !CONFIG_CAN_CALC_BITTIMING */
 static inline int
 can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
@@ -148,7 +148,7 @@ can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 static inline void
 can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 	      const struct can_bittiming *dbt,
-	      u32 *ctrlmode, u32 ctrlmode_supported)
+	      u32 tdc_mask, u32 *ctrlmode, u32 ctrlmode_supported)
 {
 }
 #endif /* CONFIG_CAN_CALC_BITTIMING */

-- 
2.49.1