kernel/linux.git/include/linux/can/bittiming.h, branch v6.19.11

can: calc_bittiming: add PWM calculation

2025-11-26T10:20:43+00:00

Perform the PWM calculation according to CiA recommendations. Note that for databitrates greater than 5 MBPS, tqmin is less than CAN_PWM_NS_MAX (which is defined to 200 nano seconds), consequently, the result of the division: DIV_ROUND_UP(xl_ns, CAN_PWM_NS_MAX) is one and thus the for loop automatically stops on the first iteration giving a single PWM symbol per bit as expected. Because of that, there is no actual need for a separate conditional branch for when the databitrate is greater than 5 MBPS. Signed-off-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20251126-canxl-v8-10-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: bittiming: add PWM validation

2025-11-26T10:20:43+00:00

Add can_validate_pwm() to validate the values pwms, pwml and pwml. Error messages are added to each of the checks to inform the user on what went wrong. Refer to those error messages to understand the validation logic. The boundary values CAN_PWM_DECODE_NS (the transceiver minimum decoding margin) and CAN_PWM_NS_MAX (the maximum PWM symbol duration) are hardcoded for the moment. Note that a transceiver capable of bitrates higher than 20 Mbps may be able to handle a CAN_PWM_DECODE_NS below 5 ns. If such transceivers become commercially available, this code could be revisited to make this parameter configurable. For now, leave it static. Signed-off-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20251126-canxl-v8-9-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: bittiming: add PWM parameters

2025-11-26T10:20:43+00:00

In CAN XL, higher data bit rates require the CAN transceiver to switch its operation mode to use Pulse-Width Modulation (PWM) transmission mode instead of the classic dominant/recessive transmission mode. The PWM parameters are: - PWMS: pulse width modulation short phase - PWML: pulse width modulation long phase - PWMO: pulse width modulation offset CiA 612-2 specifies PWMS and PWML to be at least 1 (arguably, PWML shall be at least 2 to respect the PWMS < PWML rule). PWMO's minimum is expected to always be zero. It is added more for consistency than anything else. Add struct can_pwm_const so that the different devices can provide their minimum and maximum values. When TMS is on, the runtime PWMS, PWML and PWMO are needed (either calculated or provided by the user): add struct can_pwm to store these. TDC and PWM can not be used at the same time (TDC can only be used when TMS is off and PWM only when TMS is on). struct can_pwm is thus put together with struct can_tdc inside a union to save some space. The netlink logic will be added in an upcoming change. Signed-off-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20251126-canxl-v8-8-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: netlink: add initial CAN XL support

2025-11-26T10:20:43+00:00

CAN XL uses bittiming parameters different from Classical CAN and CAN FD. Thus, all the data bittiming parameters, including TDC, need to be duplicated for CAN XL. Add the CAN XL netlink interface for all the features which are common with CAN FD. Any new CAN XL specific features are added later on. The first time CAN XL is activated, the MTU is set by default to CANXL_MAX_MTU. The user may then configure a custom MTU within the CANXL_MIN_MTU to CANXL_MAX_MTU range, in which case, the custom MTU value will be kept as long as CAN XL remains active. Signed-off-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20251126-canxl-v8-5-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: bittiming: apply NL_SET_ERR_MSG() to can_calc_bittiming()

2025-11-26T10:20:43+00:00

When CONFIG_CAN_CALC_BITTIMING is disabled, the can_calc_bittiming() functions can not be used and the user needs to provide all the bittiming parameters. Currently, can_calc_bittiming() prints an error message to the kernel log. Instead use NL_SET_ERR_MSG() to make it return the error message through the netlink interface so that the user can directly see it. Signed-off-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20251126-canxl-v8-2-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde

can: calc_bittiming: make can_calc_tdco() FD agnostic

2025-09-24T15:09:46+00:00

can_calc_tdco() uses the CAN_CTRLMODE_FD_TDC_MASK and CAN_CTRLMODE_TDC_AUTO macros making it specific to CAN FD. Add the tdc mask to the function parameter list. The value of the tdc auto flag can then be derived from that mask and stored in a local variable. This way, the function becomes CAN FD agnostic and can be reused later on for the CAN XL TDC. Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20250923-canxl-netlink-prep-v4-18-e720d28f66fe@kernel.org Signed-off-by: Marc Kleine-Budde

can: netlink: add can_validate_tdc()

2025-09-24T15:09:44+00:00

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 Link: https://patch.msgid.link/20250923-canxl-netlink-prep-v4-5-e720d28f66fe@kernel.org Signed-off-by: Marc Kleine-Budde

can: dev: make can_get_relative_tdco() FD agnostic and move it to bittiming.h

2025-09-24T15:09:44+00:00

can_get_relative_tdco() needs to access can_priv->fd making it specific to CAN FD. Change the function parameter from struct can_priv to struct data_bittiming_params. This way, the function becomes CAN FD agnostic and can be reused later on for the CAN XL TDC. Now that we dropped the dependency on struct can_priv, also move can_get_relative_tdco() back to bittiming.h where it was meant to belong to. Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20250923-canxl-netlink-prep-v4-2-e720d28f66fe@kernel.org Signed-off-by: Marc Kleine-Budde

can: dev: move struct data_bittiming_params to linux/can/bittiming.h

2025-09-24T15:09:43+00:00

In commit b803c4a4f788 ("can: dev: add struct data_bittiming_params to group FD parameters"), struct data_bittiming_params was put into linux/can/dev.h. This structure being a collection of bittiming parameters, on second thought, bittiming.h is actually a better location. This way, users of struct data_bittiming_params will not have to forcefully include linux/can/dev.h thus removing some complexity and reducing the risk of circular dependencies in headers. Move struct data_bittiming_params from linux/can/dev.h to linux/can/bittiming.h. Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20250923-canxl-netlink-prep-v4-1-e720d28f66fe@kernel.org Signed-off-by: Marc Kleine-Budde

can: bittiming: rename CAN_CTRLMODE_TDC_MASK into CAN_CTRLMODE_FD_TDC_MASK

2025-06-10T07:34:32+00:00

With the introduction of CAN XL, a new CAN_CTRLMODE_XL_TDC_MASK will be introduced later on. Because CAN_CTRLMODE_TDC_MASK is not part of the uapi, rename it to CAN_CTRLMODE_FD_TDC_MASK to make it more explicit that this mask is meant for CAN FD. Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20241112165118.586613-10-mailhol.vincent@wanadoo.fr Signed-off-by: Marc Kleine-Budde