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can: dev: can_dev_dropped_skb: drop CC/FD frames in CANXL-only mode

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The error-signalling (ES) is a mandatory functionality for CAN CC and
CAN FD to report CAN frame format violations by sending an error-frame
signal on the bus.

A so-called 'mixed-mode' is intended to have (XL-tolerant) CAN FD nodes
and CAN XL nodes on one CAN segment, where the FD-controllers can talk
CC/FD and the XL-controllers can talk CC/FD/XL. This mixed-mode
utilizes the error-signalling for sending CC/FD/XL frames.

The CANXL-only mode disables the error-signalling in the CAN XL
controller. This mode does not allow CC/FD frames to be sent but
additionally offers a CAN XL transceiver mode switching (TMS).

Configured with CAN_CTRLMODE_FD and CAN_CTRLMODE_XL this leads to:

FD=0 XL=0 CC-only mode         (ES=1)
FD=1 XL=0 FD/CC mixed-mode     (ES=1)
FD=1 XL=1 XL/FD/CC mixed-mode  (ES=1)
FD=0 XL=1 XL-only mode         (ES=0, TMS optional)

The helper function can_dev_in_xl_only_mode() determines the required
value to disable error signalling in the CAN XL controller.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251126-canxl-v8-7-e7e3eb74f889@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp
2025-11-26 11:16:08 +01:00
committed by Marc Kleine-Budde
parent 233134af20
commit 6df01533e5
1 changed files with 19 additions and 0 deletions
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19
include/linux/can/dev.h
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@@ -135,6 +135,19 @@ void can_bus_off(struct net_device *dev);
const char *can_get_state_str(const enum can_state state);
const char *can_get_ctrlmode_str(u32 ctrlmode);
static inline bool can_dev_in_xl_only_mode(struct can_priv *priv)
{
const u32 mixed_mode = CAN_CTRLMODE_FD | CAN_CTRLMODE_XL;
/* When CAN XL is enabled but FD is disabled we are running in
* the so-called 'CANXL-only mode' where the error signalling is
* disabled. This helper function determines the required value
* to disable error signalling in the CAN XL controller.
* The so-called CC/FD/XL 'mixed mode' requires error signalling.
*/
return ((priv->ctrlmode & mixed_mode) == CAN_CTRLMODE_XL);
}
/* drop skb if it does not contain a valid CAN frame for sending */
static inline bool can_dev_dropped_skb(struct net_device *dev, struct sk_buff *skb)
{
@@ -153,6 +166,12 @@ static inline bool can_dev_dropped_skb(struct net_device *dev, struct sk_buff *s
goto invalid_skb;
}
if (can_dev_in_xl_only_mode(priv) && !can_is_canxl_skb(skb)) {
netdev_info_once(dev,
"Error signaling is disabled, dropping skb\n");
goto invalid_skb;
}
return can_dropped_invalid_skb(dev, skb);
invalid_skb: