diff options
| author | Vincent Mailhol <mailhol@kernel.org> | 2025-11-26 11:16:10 +0100 |
|---|---|---|
| committer | Marc Kleine-Budde <mkl@pengutronix.de> | 2025-11-26 11:20:43 +0100 |
| commit | 8e2a2885a2a6217190065d1aae98fe88a670cc28 (patch) | |
| tree | 5a935695c5ef5cc0c6b5454db3efed4026898e3e /drivers/net | |
| parent | f6ccc2b293ba27e9171c63e456d9cba664fa2337 (diff) | |
| download | tip-8e2a2885a2a6217190065d1aae98fe88a670cc28.tar.gz | |
can: bittiming: add PWM validation
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 <mailhol@kernel.org>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251126-canxl-v8-9-e7e3eb74f889@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/can/dev/bittiming.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c index 0b93900b1dfa38..8f82418230cea2 100644 --- a/drivers/net/can/dev/bittiming.c +++ b/drivers/net/can/dev/bittiming.c @@ -2,6 +2,7 @@ /* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix * Copyright (C) 2006 Andrey Volkov, Varma Electronics * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com> + * Copyright (c) 2025 Vincent Mailhol <mailhol@kernel.org> */ #include <linux/can/dev.h> @@ -151,3 +152,65 @@ int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt, return -EINVAL; } + +int can_validate_pwm_bittiming(const struct net_device *dev, + const struct can_pwm *pwm, + struct netlink_ext_ack *extack) +{ + const struct can_priv *priv = netdev_priv(dev); + u32 xl_bit_time_tqmin = can_bit_time_tqmin(&priv->xl.data_bittiming); + u32 nom_bit_time_tqmin = can_bit_time_tqmin(&priv->bittiming); + u32 pwms_ns = can_tqmin_to_ns(pwm->pwms, priv->clock.freq); + u32 pwml_ns = can_tqmin_to_ns(pwm->pwml, priv->clock.freq); + + if (pwms_ns + pwml_ns > CAN_PWM_NS_MAX) { + NL_SET_ERR_MSG_FMT(extack, + "The PWM symbol duration: %u ns may not exceed %u ns", + pwms_ns + pwml_ns, CAN_PWM_NS_MAX); + return -EINVAL; + } + + if (pwms_ns < CAN_PWM_DECODE_NS) { + NL_SET_ERR_MSG_FMT(extack, + "PWMS: %u ns shall be at least %u ns", + pwms_ns, CAN_PWM_DECODE_NS); + return -EINVAL; + } + + if (pwm->pwms >= pwm->pwml) { + NL_SET_ERR_MSG_FMT(extack, + "PWMS: %u tqmin shall be smaller than PWML: %u tqmin", + pwm->pwms, pwm->pwml); + return -EINVAL; + } + + if (pwml_ns - pwms_ns < 2 * CAN_PWM_DECODE_NS) { + NL_SET_ERR_MSG_FMT(extack, + "At least %u ns shall separate PWMS: %u ns from PMWL: %u ns", + 2 * CAN_PWM_DECODE_NS, pwms_ns, pwml_ns); + return -EINVAL; + } + + if (xl_bit_time_tqmin % (pwm->pwms + pwm->pwml) != 0) { + NL_SET_ERR_MSG_FMT(extack, + "PWM duration: %u tqmin does not divide XL's bit time: %u tqmin", + pwm->pwms + pwm->pwml, xl_bit_time_tqmin); + return -EINVAL; + } + + if (pwm->pwmo >= pwm->pwms + pwm->pwml) { + NL_SET_ERR_MSG_FMT(extack, + "PWMO: %u tqmin can not be greater than PWMS + PWML: %u tqmin", + pwm->pwmo, pwm->pwms + pwm->pwml); + return -EINVAL; + } + + if (nom_bit_time_tqmin % (pwm->pwms + pwm->pwml) != pwm->pwmo) { + NL_SET_ERR_MSG_FMT(extack, + "Can not assemble nominal bit time: %u tqmin out of PWMS + PMWL and PWMO", + nom_bit_time_tqmin); + return -EINVAL; + } + + return 0; +} |