[PATCH v2 3/4] can: rcar_canfd: Simplify nominal bit rate config

From: Biju
Date: Thu Aug 21 2025 - 10:20:34 EST


From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Introduce rcar_canfd_compute_nominal_bit_rate_cfg() for simplifying
nominal bit rate configuration by replacing function-like macros.

Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v1->v2:
* Split from patch#3 for computing nominal bit rate config separate.
* Updated rcar_canfd_compute_nominal_bit_rate_cfg() to handle
nominal bit rate configuration for both classical CAN and CANFD.
* Replaced RCANFD_NCFG_NBRP->RCANFD_NCFG_NBRP_MASK and used FIELD_PREP to
extract value.
---
drivers/net/can/rcar/rcar_canfd.c | 45 ++++++++++++++++---------------
1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 8bae25758924..944b960c0b5e 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -109,16 +109,7 @@
#define RCANFD_CFG_BRP_MASK GENMASK(9, 0)

/* RSCFDnCFDCmNCFG - CAN FD only */
-#define RCANFD_NCFG_NTSEG2(gpriv, x) \
- (((x) & ((gpriv)->info->nom_bittiming->tseg2_max - 1)) << (gpriv)->info->sh->ntseg2)
-
-#define RCANFD_NCFG_NTSEG1(gpriv, x) \
- (((x) & ((gpriv)->info->nom_bittiming->tseg1_max - 1)) << (gpriv)->info->sh->ntseg1)
-
-#define RCANFD_NCFG_NSJW(gpriv, x) \
- (((x) & ((gpriv)->info->nom_bittiming->sjw_max - 1)) << (gpriv)->info->sh->nsjw)
-
-#define RCANFD_NCFG_NBRP(x) (((x) & 0x3ff) << 0)
+#define RCANFD_NCFG_NBRP_MASK GENMASK(9, 0)

/* RSCFDnCFDCmCTR / RSCFDnCmCTR */
#define RCANFD_CCTR_CTME BIT(24)
@@ -1393,6 +1384,28 @@ static irqreturn_t rcar_canfd_channel_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}

+static inline u32 rcar_canfd_compute_nominal_bit_rate_cfg(struct rcar_canfd_channel *priv,
+ u16 tseg1, u16 brp, u16 sjw, u16 tseg2)
+{
+ struct rcar_canfd_global *gpriv = priv->gpriv;
+ const struct rcar_canfd_hw_info *info = gpriv->info;
+ u32 ntseg2, ntseg1, nsjw, nbrp;
+
+ if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) || gpriv->info->shared_can_regs) {
+ ntseg2 = (tseg2 & (info->nom_bittiming->tseg2_max - 1)) << info->sh->ntseg2;
+ ntseg1 = (tseg1 & (info->nom_bittiming->tseg1_max - 1)) << info->sh->ntseg1;
+ nsjw = (sjw & (info->nom_bittiming->sjw_max - 1)) << info->sh->nsjw;
+ nbrp = FIELD_PREP(RCANFD_NCFG_NBRP_MASK, brp);
+ } else {
+ ntseg2 = FIELD_PREP(RCANFD_CFG_TSEG2_MASK, tseg2);
+ ntseg1 = FIELD_PREP(RCANFD_CFG_TSEG1_MASK, tseg1);
+ nsjw = FIELD_PREP(RCANFD_CFG_SJW_MASK, sjw);
+ nbrp = FIELD_PREP(RCANFD_CFG_BRP_MASK, brp);
+ }
+
+ return (ntseg1 | nbrp | nsjw | ntseg2);
+}
+
static void rcar_canfd_set_bittiming(struct net_device *ndev)
{
u32 mask = RCANFD_FDCFG_TDCO | RCANFD_FDCFG_TDCE | RCANFD_FDCFG_TDCOC;
@@ -1411,17 +1424,7 @@ static void rcar_canfd_set_bittiming(struct net_device *ndev)
sjw = bt->sjw - 1;
tseg1 = bt->prop_seg + bt->phase_seg1 - 1;
tseg2 = bt->phase_seg2 - 1;
-
- if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) || gpriv->info->shared_can_regs) {
- cfg = (RCANFD_NCFG_NTSEG1(gpriv, tseg1) | RCANFD_NCFG_NBRP(brp) |
- RCANFD_NCFG_NSJW(gpriv, sjw) | RCANFD_NCFG_NTSEG2(gpriv, tseg2));
- } else {
- cfg = FIELD_PREP(RCANFD_CFG_TSEG1_MASK, tseg1) |
- FIELD_PREP(RCANFD_CFG_BRP_MASK, brp) |
- FIELD_PREP(RCANFD_CFG_SJW_MASK, sjw) |
- FIELD_PREP(RCANFD_CFG_TSEG2_MASK, tseg2);
- }
-
+ cfg = rcar_canfd_compute_nominal_bit_rate_cfg(priv, tseg1, brp, sjw, tseg2);
rcar_canfd_write(priv->base, RCANFD_CCFG(ch), cfg);

if (!(priv->can.ctrlmode & CAN_CTRLMODE_FD))
--
2.43.0