[PATCH V3 4/7] can: flexcan: improve bittiming setting for fd mode

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From: Dong Aisheng <aisheng.dong@xxxxxxx>

Bit timing always set in CBT register other than CTRL1 register when CANFD
supports BRS, it will extend the range of all CAN bit timing variables
(PRESDIV, PROPSEG, PSEG1, PSEG2 and RJW), which will improve the bit
timing accuracy.

Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>

ChangeLog:
----------
V1->V2:
	*None
V2->V3:
	*correct the range of flexcan_fd_bittiming_const variable
---
 drivers/net/can/flexcan.c | 131 ++++++++++++++++++++++++++++----------
 1 file changed, 96 insertions(+), 35 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 662c8c8f191b..c45c92948195 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -138,6 +138,14 @@
 	 FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT | \
 	 FLEXCAN_ESR_WAK_INT)
 
+/* FLEXCAN Bit Timing register (CBT) bits */
+#define FLEXCAN_CBT_BTF		        BIT(31)
+#define FLEXCAN_CBT_EPRESDIV(x)	        (((x) & 0x3ff) << 21)
+#define FLEXCAN_CBT_ERJW(x)		(((x) & 0x1f) << 16)
+#define FLEXCAN_CBT_EPROPSEG(x)	        (((x) & 0x3f) << 10)
+#define FLEXCAN_CBT_EPSEG1(x)		(((x) & 0x1f) << 5)
+#define FLEXCAN_CBT_EPSEG2(x)		((x) & 0x1f)
+
 /* FLEXCAN FD control register (FDCTRL) bits */
 #define FLEXCAN_FDCTRL_FDRATE		BIT(31)
 #define FLEXCAN_FDCTRL_MBDSR3(x)	(((x) & 0x3) << 25)
@@ -245,7 +253,8 @@ struct flexcan_regs {
 	u32 crcr;		/* 0x44 */
 	u32 rxfgmask;		/* 0x48 */
 	u32 rxfir;		/* 0x4c */
-	u32 _reserved3[12];	/* 0x50 */
+	u32 cbt;                /* 0x50 */
+	u32 _reserved3[11];     /* 0x54 */
 	u8 mb[2][512];		/* 0x80 */
 	/* FIFO-mode:
 	 *			MB
@@ -360,6 +369,18 @@ static const struct can_bittiming_const flexcan_bittiming_const = {
 	.brp_inc = 1,
 };
 
+static const struct can_bittiming_const flexcan_fd_bittiming_const = {
+	.name = DRV_NAME,
+	.tseg1_min = 2,
+	.tseg1_max = 64,
+	.tseg2_min = 2,
+	.tseg2_max = 32,
+	.sjw_max = 32,
+	.brp_min = 1,
+	.brp_max = 1024,
+	.brp_inc = 1,
+};
+
 static const struct can_bittiming_const flexcan_fd_data_bittiming_const = {
 	.name = DRV_NAME,
 	.tseg1_min = 2,
@@ -1048,24 +1069,10 @@ static void flexcan_set_bittiming(struct net_device *dev)
 	const struct can_bittiming *bt = &priv->can.bittiming;
 	const struct can_bittiming *dbt = &priv->can.data_bittiming;
 	struct flexcan_regs __iomem *regs = priv->regs;
-	u32 reg, reg_fdcbt;
+	u32 reg, reg_cbt, reg_fdcbt;
 
 	reg = priv->read(&regs->ctrl);
-	reg &= ~(FLEXCAN_CTRL_PRESDIV(0xff) |
-		 FLEXCAN_CTRL_RJW(0x3) |
-		 FLEXCAN_CTRL_PSEG1(0x7) |
-		 FLEXCAN_CTRL_PSEG2(0x7) |
-		 FLEXCAN_CTRL_PROPSEG(0x7) |
-		 FLEXCAN_CTRL_LPB |
-		 FLEXCAN_CTRL_SMP |
-		 FLEXCAN_CTRL_LOM);
-
-	reg |= FLEXCAN_CTRL_PRESDIV(bt->brp - 1) |
-		FLEXCAN_CTRL_PSEG1(bt->phase_seg1 - 1) |
-		FLEXCAN_CTRL_PSEG2(bt->phase_seg2 - 1) |
-		FLEXCAN_CTRL_RJW(bt->sjw - 1) |
-		FLEXCAN_CTRL_PROPSEG(bt->prop_seg - 1);
-
+	reg &= ~(FLEXCAN_CTRL_LPB | FLEXCAN_CTRL_SMP | FLEXCAN_CTRL_LOM);
 	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
 		reg |= FLEXCAN_CTRL_LPB;
 	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
@@ -1076,25 +1083,78 @@ static void flexcan_set_bittiming(struct net_device *dev)
 	netdev_dbg(dev, "writing ctrl=0x%08x\n", reg);
 	priv->write(reg, &regs->ctrl);
 
-	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
-		reg_fdcbt = priv->read(&regs->fdcbt);
-		reg_fdcbt &= ~(FLEXCAN_FDCBT_FPRESDIV(0x3ff) |
-			       FLEXCAN_FDCBT_FPSEG1(0x07) |
-			       FLEXCAN_FDCBT_FPSEG2(0x07) |
-			       FLEXCAN_FDCBT_FRJW(0x07) |
-			       FLEXCAN_FDCBT_FPROPSEG(0x1f));
-
-		reg_fdcbt = FLEXCAN_FDCBT_FPRESDIV(dbt->brp - 1) |
-				FLEXCAN_FDCBT_FPSEG1(dbt->phase_seg1 - 1) |
-				FLEXCAN_FDCBT_FPSEG2(dbt->phase_seg2 - 1) |
-				FLEXCAN_FDCBT_FRJW(dbt->sjw - 1) |
-				FLEXCAN_FDCBT_FPROPSEG(dbt->prop_seg);
-		priv->write(reg_fdcbt, &regs->fdcbt);
-	}
+	if (priv->can.ctrlmode_supported & CAN_CTRLMODE_FD) {
+		reg_cbt = priv->read(&regs->cbt);
+		reg_cbt &= ~(FLEXCAN_CBT_EPRESDIV(0x3ff) |
+			     FLEXCAN_CBT_EPSEG1(0x1f) |
+			     FLEXCAN_CBT_EPSEG2(0x1f) |
+			     FLEXCAN_CBT_ERJW(0x1f) |
+			     FLEXCAN_CBT_EPROPSEG(0x3f) |
+			     FLEXCAN_CBT_BTF);
+
+		reg_cbt = FLEXCAN_CBT_EPRESDIV(bt->brp - 1) |
+				FLEXCAN_CBT_EPSEG1(bt->phase_seg1 - 1) |
+				FLEXCAN_CBT_EPSEG2(bt->phase_seg2 - 1) |
+				FLEXCAN_CBT_ERJW(bt->sjw - 1) |
+				FLEXCAN_CBT_EPROPSEG(bt->prop_seg - 1) |
+				FLEXCAN_CBT_BTF;
+		priv->write(reg_cbt, &regs->cbt);
+
+		netdev_dbg(dev, "bt: prediv %d seg1 %d seg2 %d rjw %d propseg %d\n",
+			   bt->brp - 1, bt->phase_seg1 - 1, bt->phase_seg2 - 1,
+			   bt->sjw - 1, bt->prop_seg - 1);
 
-	/* print chip status */
-	netdev_dbg(dev, "%s: mcr=0x%08x ctrl=0x%08x\n", __func__,
-		   priv->read(&regs->mcr), priv->read(&regs->ctrl));
+		if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
+			reg_fdcbt = priv->read(&regs->fdcbt);
+			reg_fdcbt &= ~(FLEXCAN_FDCBT_FPRESDIV(0x3ff) |
+				       FLEXCAN_FDCBT_FPSEG1(0x07) |
+				       FLEXCAN_FDCBT_FPSEG2(0x07) |
+				       FLEXCAN_FDCBT_FRJW(0x07) |
+				       FLEXCAN_FDCBT_FPROPSEG(0x1f));
+
+			reg_fdcbt = FLEXCAN_FDCBT_FPRESDIV(dbt->brp - 1) |
+					FLEXCAN_FDCBT_FPSEG1(dbt->phase_seg1 - 1) |
+					FLEXCAN_FDCBT_FPSEG2(dbt->phase_seg2 - 1) |
+					FLEXCAN_FDCBT_FRJW(dbt->sjw - 1) |
+					FLEXCAN_FDCBT_FPROPSEG(dbt->prop_seg);
+			priv->write(reg_fdcbt, &regs->fdcbt);
+
+			if (bt->brp != dbt->brp)
+				netdev_warn(dev, "prescaler of bitrate and dbitrate not the same, may risk errors when transfer CAN FD format frames with Bit Rate Switch\n");
+
+			netdev_dbg(dev, "fdbt: prediv %d seg1 %d seg2 %d rjw %d propseg %d\n",
+				   dbt->brp - 1, dbt->phase_seg1 - 1, dbt->phase_seg2 - 1,
+				   dbt->sjw - 1, dbt->prop_seg);
+
+			netdev_dbg(dev, "%s: mcr=0x%08x ctrl=0x%08x cbt=0x%08x fdcbt=0x%08x\n",
+				   __func__, priv->read(&regs->mcr),
+				   priv->read(&regs->ctrl),
+				   priv->read(&regs->cbt),
+				   priv->read(&regs->fdcbt));
+		}
+	} else {
+		reg = priv->read(&regs->ctrl);
+		reg &= ~(FLEXCAN_CTRL_PRESDIV(0xff) |
+			 FLEXCAN_CTRL_RJW(0x3) |
+			 FLEXCAN_CTRL_PSEG1(0x7) |
+			 FLEXCAN_CTRL_PSEG2(0x7) |
+			 FLEXCAN_CTRL_PROPSEG(0x7));
+
+		reg |= FLEXCAN_CTRL_PRESDIV(bt->brp - 1) |
+			FLEXCAN_CTRL_PSEG1(bt->phase_seg1 - 1) |
+			FLEXCAN_CTRL_PSEG2(bt->phase_seg2 - 1) |
+			FLEXCAN_CTRL_RJW(bt->sjw - 1) |
+			FLEXCAN_CTRL_PROPSEG(bt->prop_seg - 1);
+		priv->write(reg, &regs->ctrl);
+
+		netdev_dbg(dev, "bt: prediv %d seg1 %d seg2 %d rjw %d propseg %d\n",
+			   bt->brp - 1, bt->phase_seg1 - 1, bt->phase_seg2 - 1,
+			   bt->sjw - 1, bt->prop_seg - 1);
+
+		/* print chip status */
+		netdev_dbg(dev, "%s: mcr=0x%08x ctrl=0x%08x\n", __func__,
+			   priv->read(&regs->mcr), priv->read(&regs->ctrl));
+	}
 }
 
 /* flexcan_chip_start
@@ -1713,6 +1773,7 @@ static int flexcan_probe(struct platform_device *pdev)
 	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_TIMESTAMP_SUPPORT_FD) {
 		if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_OFF_TIMESTAMP) {
 			priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
+			priv->can.bittiming_const = &flexcan_fd_bittiming_const;
 			priv->can.data_bittiming_const = &flexcan_fd_data_bittiming_const;
 		} else {
 			dev_err(&pdev->dev, "can fd mode can't work on fifo mode\n");
-- 
2.17.1
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