Merge patch series "can: netlink: add CAN XL support"

Marc Kleine-Budde <mkl@pengutronix.de> says:

Similarly to how CAN FD reuses the bittiming logic of Classical CAN, CAN XL
also reuses the entirety of CAN FD features, and, on top of that, adds new
features which are specific to CAN XL.

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
known error-signalling (ES) for sending CC/FD/XL frames. For CAN FD and CAN
XL the tranceiver delay compensation (TDC) is supported to use common CAN
and CAN-SIG transceivers.

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) to send CAN XL frames with up to
20Mbit/s data rate. The TMS utilizes a PWM configuration which is added to
the netlink interface.

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)

Patch #1 print defined ctrlmode strings capitalized to increase the
readability and to be in line with the 'ip' tool (iproute2).

Patch #2 is a small clean-up which makes can_calc_bittiming() use
NL_SET_ERR_MSG() instead of netdev_err().

Patch #3 adds a check in can_dev_dropped_skb() to drop CAN FD frames
when CAN FD is turned off.

Patch #4 adds CAN_CTRLMODE_RESTRICTED. Note that contrary to the other
CAN_CTRL_MODE_XL_* that are introduced in the later patches, this control
mode is not specific to CAN XL. The nuance is that because this restricted
mode was only added in ISO 11898-1:2024, it is made mandatory for CAN XL
devices but optional for other protocols. This is why this patch is added
as a preparation before introducing the core CAN XL logic.

Patch #5 adds all the CAN XL features which are inherited from CAN FD: the
nominal bittiming, the data bittiming and the TDC.

Patch #6 add a new CAN_CTRLMODE_XL_TMS control mode which is specific to
CAN XL to enable the transceiver mode switching (TMS) in XL-only mode.

Patch #7 adds a check in can_dev_dropped_skb() to drop CAN CC/FD frames
when the CAN XL controller is in CAN XL-only mode. The introduced
can_dev_in_xl_only_mode() function also determines the error-signalling
configuration for the CAN XL controllers.

Patch #8 to #11 add the PWM logic for the CAN XL TMS mode.

Patch #12 to #14 add different default sample-points for standard CAN and
CAN SIG transceivers (with TDC) and CAN XL transceivers using PWM in the
CAN XL TMS mode.

Patch #15 add a dummy_can driver for netlink testing and debugging.

Patch #16 check CAN frame type (CC/FD/XL) when writing those frames to the
CAN_RAW socket and reject them if it's not supported by the CAN interface.

Patch #17 increase the resolution when printing the bitrate error and
round-up the value to 0.01% in the case the resolution would still provide
values which would lead to 0.00%.

Link: https://patch.msgid.link/20251126-canxl-v8-0-e7e3eb74f889@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

2 files changed, 127 insertions, 22 deletions

diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h
index d30816dd93c7..726d909e87ce 100644
--- a/include/linux/can/bittiming.h
+++ b/include/linux/can/bittiming.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
- * Copyright (c) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
+ * Copyright (c) 2021-2025 Vincent Mailhol <mailhol@kernel.org>
  */
 
 #ifndef _CAN_BITTIMING_H
@@ -16,10 +16,12 @@
 
 #define CAN_CTRLMODE_FD_TDC_MASK				\
 	(CAN_CTRLMODE_TDC_AUTO | CAN_CTRLMODE_TDC_MANUAL)
+#define CAN_CTRLMODE_XL_TDC_MASK				\
+	(CAN_CTRLMODE_XL_TDC_AUTO | CAN_CTRLMODE_XL_TDC_MANUAL)
 #define CAN_CTRLMODE_TDC_AUTO_MASK				\
-	(CAN_CTRLMODE_TDC_AUTO)
+	(CAN_CTRLMODE_TDC_AUTO | CAN_CTRLMODE_XL_TDC_AUTO)
 #define CAN_CTRLMODE_TDC_MANUAL_MASK				\
-	(CAN_CTRLMODE_TDC_MANUAL)
+	(CAN_CTRLMODE_TDC_MANUAL | CAN_CTRLMODE_XL_TDC_MANUAL)
 
 /*
  * struct can_tdc - CAN FD Transmission Delay Compensation parameters
@@ -85,6 +87,11 @@ struct can_tdc {
 	u32 tdcf;
 };
 
+/* The transceiver decoding margin corresponds to t_Decode in ISO 11898-2 */
+#define CAN_PWM_DECODE_NS 5
+/* Maximum PWM symbol duration. Corresponds to t_SymbolNom_MAX - t_Decode */
+#define CAN_PWM_NS_MAX (205 - CAN_PWM_DECODE_NS)
+
 /*
  * struct can_tdc_const - CAN hardware-dependent constant for
  *	Transmission Delay Compensation
@@ -118,11 +125,48 @@ struct can_tdc_const {
 	u32 tdcf_max;
 };
 
+/*
+ * struct can_pwm - CAN Pulse-Width Modulation (PWM) parameters
+ *
+ * @pwms: pulse width modulation short phase
+ * @pwml: pulse width modulation long phase
+ * @pwmo: pulse width modulation offset
+ */
+struct can_pwm {
+	u32 pwms;
+	u32 pwml;
+	u32 pwmo;
+};
+
+/*
+ * struct can_pwm - CAN hardware-dependent constants for Pulse-Width
+ *	Modulation (PWM)
+ *
+ * @pwms_min: PWM short phase minimum value. Must be at least 1.
+ * @pwms_max: PWM short phase maximum value
+ * @pwml_min: PWM long phase minimum value. Must be at least 1.
+ * @pwml_max: PWM long phase maximum value
+ * @pwmo_min: PWM offset phase minimum value
+ * @pwmo_max: PWM offset phase maximum value
+ */
+struct can_pwm_const {
+	u32 pwms_min;
+	u32 pwms_max;
+	u32 pwml_min;
+	u32 pwml_max;
+	u32 pwmo_min;
+	u32 pwmo_max;
+};
+
 struct data_bittiming_params {
 	const struct can_bittiming_const *data_bittiming_const;
 	struct can_bittiming data_bittiming;
 	const struct can_tdc_const *tdc_const;
-	struct can_tdc tdc;
+	const struct can_pwm_const *pwm_const;
+	union {
+		struct can_tdc tdc;
+		struct can_pwm pwm;
+	};
 	const u32 *data_bitrate_const;
 	unsigned int data_bitrate_const_cnt;
 	int (*do_set_data_bittiming)(struct net_device *dev);
@@ -136,12 +180,14 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		   const struct can_bittiming *dbt,
 		   u32 tdc_mask, u32 *ctrlmode, u32 ctrlmode_supported);
+
+int can_calc_pwm(struct net_device *dev, struct netlink_ext_ack *extack);
 #else /* !CONFIG_CAN_CALC_BITTIMING */
 static inline int
 can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		   const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)
 {
-	netdev_err(dev, "bit-timing calculation not available\n");
+	NL_SET_ERR_MSG(extack, "bit-timing calculation not available\n");
 	return -EINVAL;
 }
 
@@ -151,6 +197,14 @@ can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 	      u32 tdc_mask, u32 *ctrlmode, u32 ctrlmode_supported)
 {
 }
+
+static inline int
+can_calc_pwm(struct net_device *dev, struct netlink_ext_ack *extack)
+{
+	NL_SET_ERR_MSG(extack,
+		       "bit-timing calculation not available: manually provide PWML and PWMS\n");
+	return -EINVAL;
+}
 #endif /* CONFIG_CAN_CALC_BITTIMING */
 
 void can_sjw_set_default(struct can_bittiming *bt);
@@ -164,6 +218,10 @@ int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		      const unsigned int bitrate_const_cnt,
 		      struct netlink_ext_ack *extack);
 
+int can_validate_pwm_bittiming(const struct net_device *dev,
+			       const struct can_pwm *pwm,
+			       struct netlink_ext_ack *extack);
+
 /*
  * can_get_relative_tdco() - TDCO relative to the sample point
  *
@@ -206,4 +264,17 @@ static inline unsigned int can_bit_time(const struct can_bittiming *bt)
 	return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
 }
 
+/* Duration of one bit in minimum time quantum */
+static inline unsigned int can_bit_time_tqmin(const struct can_bittiming *bt)
+{
+	return can_bit_time(bt) * bt->brp;
+}
+
+/* Convert a duration from minimum a minimum time quantum to nano seconds */
+static inline u32 can_tqmin_to_ns(u32 tqmin, u32 clock_freq)
+{
+	return DIV_U64_ROUND_CLOSEST(mul_u32_u32(tqmin, NSEC_PER_SEC),
+				     clock_freq);
+}
+
 #endif /* !_CAN_BITTIMING_H */
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index bd7410b5d8a6..52c8be5c160e 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -47,7 +47,7 @@ struct can_priv {
 
 	const struct can_bittiming_const *bittiming_const;
 	struct can_bittiming bittiming;
-	struct data_bittiming_params fd;
+	struct data_bittiming_params fd, xl;
 	unsigned int bitrate_const_cnt;
 	const u32 *bitrate_const;
 	u32 bitrate_max;
@@ -85,6 +85,11 @@ static inline bool can_fd_tdc_is_enabled(const struct can_priv *priv)
 	return !!(priv->ctrlmode & CAN_CTRLMODE_FD_TDC_MASK);
 }
 
+static inline bool can_xl_tdc_is_enabled(const struct can_priv *priv)
+{
+	return !!(priv->ctrlmode & CAN_CTRLMODE_XL_TDC_MASK);
+}
+
 static inline u32 can_get_static_ctrlmode(struct can_priv *priv)
 {
 	return priv->ctrlmode & ~priv->ctrlmode_supported;
@@ -95,22 +100,6 @@ static inline bool can_is_canxl_dev_mtu(unsigned int mtu)
 	return (mtu >= CANXL_MIN_MTU && mtu <= CANXL_MAX_MTU);
 }
 
-/* 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)
-{
-	struct can_priv *priv = netdev_priv(dev);
-
-	if (priv->ctrlmode & CAN_CTRLMODE_LISTENONLY) {
-		netdev_info_once(dev,
-				 "interface in listen only mode, dropping skb\n");
-		kfree_skb(skb);
-		dev->stats.tx_dropped++;
-		return true;
-	}
-
-	return can_dropped_invalid_skb(dev, skb);
-}
-
 void can_setup(struct net_device *dev);
 
 struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
@@ -146,6 +135,51 @@ 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)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	u32 silent_mode = priv->ctrlmode & (CAN_CTRLMODE_LISTENONLY |
+					    CAN_CTRLMODE_RESTRICTED);
+
+	if (silent_mode) {
+		netdev_info_once(dev, "interface in %s mode, dropping skb\n",
+				 can_get_ctrlmode_str(silent_mode));
+		goto invalid_skb;
+	}
+
+	if (!(priv->ctrlmode & CAN_CTRLMODE_FD) && can_is_canfd_skb(skb)) {
+		netdev_info_once(dev, "CAN FD is disabled, dropping skb\n");
+		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:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return true;
+}
+
 void can_state_get_by_berr_counter(const struct net_device *dev,
 				   const struct can_berr_counter *bec,
 				   enum can_state *tx_state,