Factorise the TDC validation out of can_validate() and move it in the
new can_validate_tdc() function. This is a preparation patch for the
introduction of CAN XL because this TDC validation will be reused
later on.

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

RFC -> v1:

  - fix bug on tdc flags mutual exclusivity:
      'if (tdc_auto == tdc_manual)' -> 'if (tdc_auto && tdc_manual)'
---
 drivers/net/can/dev/netlink.c | 82 +++++++++++++++++++++++++------------------
 include/linux/can/bittiming.h |  4 +++
 2 files changed, 52 insertions(+), 34 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 13555253e789ec6ca9c8c30571c990ad6bfde770..25c08adee9ade22a5dabdd3dec1b5eb1ee16a78e 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -57,6 +57,49 @@ static int can_validate_bittiming(struct nlattr *data[],
 	return 0;
 }
 
+static int can_validate_tdc(struct nlattr *data_tdc,
+			    struct netlink_ext_ack *extack, u32 tdc_flags)
+{
+	bool tdc_manual = tdc_flags & CAN_CTRLMODE_TDC_MANUAL_MASK;
+	bool tdc_auto = tdc_flags & CAN_CTRLMODE_TDC_AUTO_MASK;
+	int err;
+
+	/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually exclusive */
+	if (tdc_auto && tdc_manual)
+		return -EOPNOTSUPP;
+
+	/* If one of the CAN_CTRLMODE_TDC_* flag is set then TDC
+	 * must be set and vice-versa
+	 */
+	if ((tdc_auto || tdc_manual) != !!data_tdc)
+		return -EOPNOTSUPP;
+
+	/* If providing TDC parameters, at least TDCO is needed. TDCV
+	 * is needed if and only if CAN_CTRLMODE_TDC_MANUAL is set
+	 */
+	if (data_tdc) {
+		struct nlattr *tb_tdc[IFLA_CAN_TDC_MAX + 1];
+
+		err = nla_parse_nested(tb_tdc, IFLA_CAN_TDC_MAX,
+				       data_tdc, can_tdc_policy, extack);
+		if (err)
+			return err;
+
+		if (tb_tdc[IFLA_CAN_TDC_TDCV]) {
+			if (tdc_auto)
+				return -EOPNOTSUPP;
+		} else {
+			if (tdc_manual)
+				return -EOPNOTSUPP;
+		}
+
+		if (!tb_tdc[IFLA_CAN_TDC_TDCO])
+			return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
 static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 			struct netlink_ext_ack *extack)
 {
@@ -67,7 +110,7 @@ static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 	 * - nominal/arbitration bittiming
 	 * - data bittiming
 	 * - control mode with CAN_CTRLMODE_FD set
-	 * - TDC parameters are coherent (details below)
+	 * - TDC parameters are coherent (details in can_validate_tdc())
 	 */
 
 	if (!data)
@@ -75,42 +118,13 @@ static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 
 	if (data[IFLA_CAN_CTRLMODE]) {
 		struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
-		u32 tdc_flags = cm->flags & CAN_CTRLMODE_FD_TDC_MASK;
 
 		is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
 
-		/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually exclusive */
-		if (tdc_flags == CAN_CTRLMODE_FD_TDC_MASK)
-			return -EOPNOTSUPP;
-		/* If one of the CAN_CTRLMODE_TDC_* flag is set then
-		 * TDC must be set and vice-versa
-		 */
-		if (!!tdc_flags != !!data[IFLA_CAN_TDC])
-			return -EOPNOTSUPP;
-		/* If providing TDC parameters, at least TDCO is
-		 * needed. TDCV is needed if and only if
-		 * CAN_CTRLMODE_TDC_MANUAL is set
-		 */
-		if (data[IFLA_CAN_TDC]) {
-			struct nlattr *tb_tdc[IFLA_CAN_TDC_MAX + 1];
-
-			err = nla_parse_nested(tb_tdc, IFLA_CAN_TDC_MAX,
-					       data[IFLA_CAN_TDC],
-					       can_tdc_policy, extack);
-			if (err)
-				return err;
-
-			if (tb_tdc[IFLA_CAN_TDC_TDCV]) {
-				if (tdc_flags & CAN_CTRLMODE_TDC_AUTO)
-					return -EOPNOTSUPP;
-			} else {
-				if (tdc_flags & CAN_CTRLMODE_TDC_MANUAL)
-					return -EOPNOTSUPP;
-			}
-
-			if (!tb_tdc[IFLA_CAN_TDC_TDCO])
-				return -EOPNOTSUPP;
-		}
+		err = can_validate_tdc(data[IFLA_CAN_TDC], extack,
+				       cm->flags & CAN_CTRLMODE_FD_TDC_MASK);
+		if (err)
+			return err;
 	}
 
 	err = can_validate_bittiming(data, extack, IFLA_CAN_BITTIMING);
diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h
index 4d5f7794194ab13641c7854c2d66625c4e942f6c..71f839c3f0325b2a496a4bc447044a4853541338 100644
--- a/include/linux/can/bittiming.h
+++ b/include/linux/can/bittiming.h
@@ -16,6 +16,10 @@
 
 #define CAN_CTRLMODE_FD_TDC_MASK				\
 	(CAN_CTRLMODE_TDC_AUTO | CAN_CTRLMODE_TDC_MANUAL)
+#define CAN_CTRLMODE_TDC_AUTO_MASK				\
+	(CAN_CTRLMODE_TDC_AUTO)
+#define CAN_CTRLMODE_TDC_MANUAL_MASK				\
+	(CAN_CTRLMODE_TDC_MANUAL)
 
 /*
  * struct can_tdc - CAN FD Transmission Delay Compensation parameters

-- 
2.49.1