[RFC PATCH 07/14] can: netlink: add can_dtb_changelink()

[Vincent Mailhol <mailhol.vincent@wanadoo.fr>]

Factorize the dattabittiming parsing out of can_changelink() and move
it in the new can_dtb_changelink() function. This is a preparation
patch for the introduction of CAN XL because the databittiming
changelink logic will be reused later on.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
---
I am not fully happy that can_dbt_changelink() requires 8 parameters.
I will probably revisit this later on. But for the moment, I think
this is acceptable for an RFC.
---
 drivers/net/can/dev/netlink.c | 139 +++++++++++++++++++---------------
 1 file changed, 78 insertions(+), 61 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 50c1658f17a4..354846e3a0d0 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -185,6 +185,77 @@ static int can_tdc_changelink(struct data_bittiming_params *dbt_params,
 	return 0;
 }
 
+static int can_dbt_changelink(struct net_device *dev,
+			      struct nlattr *data_databittiming,
+			      struct data_bittiming_params *dbt_params,
+			      struct nlattr *data_tdc, bool tdc_flags_provided,
+			      bool tdc_is_enabled, u32 tdc_mask,
+			      struct netlink_ext_ack *extack)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	struct can_bittiming dbt;
+	int err;
+
+	if (!data_databittiming)
+		return 0;
+
+	/* Do not allow changing bittiming while running */
+	if (dev->flags & IFF_UP)
+		return -EBUSY;
+
+	/* Calculate bittiming parameters based on data_bittiming_const
+	 * if set, otherwise pass bitrate directly via do_set_bitrate().
+	 * Bail out if neither is given.
+	 */
+	if (!dbt_params->data_bittiming_const && !dbt_params->do_set_data_bittiming &&
+	    !dbt_params->data_bitrate_const)
+		return -EOPNOTSUPP;
+
+	memcpy(&dbt, nla_data(data_databittiming), sizeof(dbt));
+	err = can_get_bittiming(dev, &dbt, dbt_params->data_bittiming_const,
+				dbt_params->data_bitrate_const,
+				dbt_params->data_bitrate_const_cnt, extack);
+	if (err)
+		return err;
+
+	if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) {
+		NL_SET_ERR_MSG_FMT(extack,
+				   "CAN data bitrate %u bps surpasses transceiver capabilities of %u bps",
+				   dbt.bitrate, priv->bitrate_max);
+		return -EINVAL;
+	}
+
+	memset(&dbt_params->tdc, 0, sizeof(dbt_params->tdc));
+	if (data_tdc) {
+		/* TDC parameters are provided: use them */
+		err = can_tdc_changelink(dbt_params, tdc_is_enabled, data_tdc,
+					 extack);
+		if (err) {
+			priv->ctrlmode &= ~tdc_mask;
+			return err;
+		}
+	} else if (!tdc_flags_provided) {
+		/* Neither of TDC parameters nor TDC flags are provided:
+		 * do calculation
+		 */
+		can_calc_tdco(&dbt_params->tdc, dbt_params->tdc_const, &dbt,
+			      &priv->ctrlmode, priv->ctrlmode_supported);
+	} /* else: both CAN_CTRLMODE_TDC_{AUTO,MANUAL} are explicitly
+	   * turned off. TDC is disabled: do nothing
+	   */
+
+	memcpy(&dbt_params->data_bittiming, &dbt, sizeof(dbt));
+
+	if (dbt_params->do_set_data_bittiming) {
+		/* Finally, set the bit-timing registers */
+		err = dbt_params->do_set_data_bittiming(dev);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			  struct nlattr *data[],
 			  struct netlink_ext_ack *extack)
@@ -301,67 +372,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			return err;
 	}
 
-	if (data[IFLA_CAN_DATA_BITTIMING]) {
-		struct can_bittiming dbt;
-
-		/* Do not allow changing bittiming while running */
-		if (dev->flags & IFF_UP)
-			return -EBUSY;
-
-		/* Calculate bittiming parameters based on
-		 * data_bittiming_const if set, otherwise pass bitrate
-		 * directly via do_set_bitrate(). Bail out if neither
-		 * is given.
-		 */
-		if (!priv->fd.data_bittiming_const && !priv->fd.do_set_data_bittiming &&
-		    !priv->fd.data_bitrate_const)
-			return -EOPNOTSUPP;
-
-		memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
-		       sizeof(dbt));
-		err = can_get_bittiming(dev, &dbt,
-					priv->fd.data_bittiming_const,
-					priv->fd.data_bitrate_const,
-					priv->fd.data_bitrate_const_cnt,
-					extack);
-		if (err)
-			return err;
-
-		if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) {
-			NL_SET_ERR_MSG_FMT(extack,
-					   "CANFD data bitrate %u bps surpasses transceiver capabilities of %u bps",
-					   dbt.bitrate, priv->bitrate_max);
-			return -EINVAL;
-		}
-
-		memset(&priv->fd.tdc, 0, sizeof(priv->fd.tdc));
-		if (data[IFLA_CAN_TDC]) {
-			/* TDC parameters are provided: use them */
-			err = can_tdc_changelink(&priv->fd, can_fd_tdc_is_enabled(priv),
-						 data[IFLA_CAN_TDC], extack);
-			if (err) {
-				priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
-				return err;
-			}
-		} else if (!fd_tdc_flag_provided) {
-			/* Neither of TDC parameters nor TDC flags are
-			 * provided: do calculation
-			 */
-			can_calc_tdco(&priv->fd.tdc, priv->fd.tdc_const, &dbt,
-				      &priv->ctrlmode, priv->ctrlmode_supported);
-		} /* else: both CAN_CTRLMODE_TDC_{AUTO,MANUAL} are explicitly
-		   * turned off. TDC is disabled: do nothing
-		   */
-
-		memcpy(&priv->fd.data_bittiming, &dbt, sizeof(dbt));
-
-		if (priv->fd.do_set_data_bittiming) {
-			/* Finally, set the bit-timing registers */
-			err = priv->fd.do_set_data_bittiming(dev);
-			if (err)
-				return err;
-		}
-	}
+	/* CAN FD */
+	err = can_dbt_changelink(dev, data[IFLA_CAN_DATA_BITTIMING], &priv->fd,
+				 data[IFLA_CAN_TDC], fd_tdc_flag_provided,
+				 can_fd_tdc_is_enabled(priv),
+				 CAN_CTRLMODE_FD_TDC_MASK, extack);
+	if (err)
+		return err;
 
 	if (data[IFLA_CAN_TERMINATION]) {
 		const u16 termval = nla_get_u16(data[IFLA_CAN_TERMINATION]);
-- 
2.45.2