From nobody Mon Dec 1 23:03:13 2025 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B0B4301481 for ; Wed, 26 Nov 2025 10:17:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764152227; cv=none; b=TL1ghDy12pjbjWcLrS5i6B/EybZefl1nCaH/rZPh+IJAubsqHgyf35qG+1C0AkcbLCJ+6Simt2qkW3hxXVdrYcEeEQg2Nw67mJ5HIG8TqjGEyrr3GoCrMoBk0Mpkg3rqFN1sWPZYUbWT6qPA8CsegqBKlHxJr6i8suB5u01D2+M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764152227; c=relaxed/simple; bh=ZFFwKnOvhSuIBWQDDMv6kaAVREw0gWi28fIysXwta3U=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=p+bGUo9hA/I07DqsnxgFRcVt4DCSmPyCdDhiZgKiT+ZKaBjjVcQUyGE7q99hvyI8kGPCoEu1Ami9koIUFExV8I8JUnw3kpog1TPwYh7sVs0T1SsSv1ZrS6o2mdghB4FpwKc7PBjBsG95NfZ3/PpWUsafE6cuQbCRnVzd2P/J/2E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1vOCZv-0000Qy-R7; Wed, 26 Nov 2025 11:16:51 +0100 Received: from moin.white.stw.pengutronix.de ([2a0a:edc0:0:b01:1d::7b] helo=bjornoya.blackshift.org) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1vOCZv-002aSq-0d; Wed, 26 Nov 2025 11:16:51 +0100 Received: from hardanger.blackshift.org (p54b152ce.dip0.t-ipconnect.de [84.177.82.206]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id F00B44A88DA; Wed, 26 Nov 2025 10:16:50 +0000 (UTC) From: Marc Kleine-Budde Date: Wed, 26 Nov 2025 11:16:10 +0100 Subject: [PATCH can-next v8 09/17] can: bittiming: add PWM validation Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251126-canxl-v8-9-e7e3eb74f889@pengutronix.de> References: <20251126-canxl-v8-0-e7e3eb74f889@pengutronix.de> In-Reply-To: <20251126-canxl-v8-0-e7e3eb74f889@pengutronix.de> To: Marc Kleine-Budde , Vincent Mailhol , Oliver Hartkopp Cc: kernel@pengutronix.de, linux-can@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?St=C3=A9phane_Grosjean?= X-Mailer: b4 0.15-dev-a6db3 X-Developer-Signature: v=1; a=openpgp-sha256; l=5299; i=mkl@pengutronix.de; h=from:subject:message-id; bh=yx/q9gOPPA1BdZiOSo8vRRu2MKMazlfUmz0y7rZkgRA=; b=owEBbQGS/pANAwAKAQx0Zd/5kJGcAcsmYgBpJtOC/yX8qNJz2FqhZhSZbU68ALNQaLeZAiO3D KfEmdsL+mWJATMEAAEKAB0WIQSf+wzYr2eoX/wVbPMMdGXf+ZCRnAUCaSbTggAKCRAMdGXf+ZCR nJyXCAC1201Z7zcCgT/cbXyHX5ciqqn3iBaApYUR5a8gFh/jPQwa9cmBcqdrZqC92nvu9m9d/Z0 52lmr5fJb/2S1E4luuP7bNcevL2BWrWikIS2GdI9qiHCxIQ3ErTw9t6x52NzbxkpNMb81B+WvMo AMhk0cZG83jI60dyQOd5eAFNeCKmb758mDJaZKV9js+WeEyJcTUMrKlafP8TZ0OK41K5L/nHZgj F95fma3+ISoe+CKMAmdOdaHgvgKCCPjJR0jNZES3RpFjbMj3uthgzw/beD42deb6kbl/Xe5ezac /Ldy3R19chhVt6c4H9TklGWHxwHAqCGnEU/UdGVouFz0tv2o X-Developer-Key: i=mkl@pengutronix.de; a=openpgp; fpr=C1400BA0B3989E6FBC7D5B5C2B5EE211C58AEA54 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org From: Vincent Mailhol 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 Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev/bittiming.c | 63 +++++++++++++++++++++++++++++++++++++= ++++ include/linux/can/bittiming.h | 22 ++++++++++++++ 2 files changed, 85 insertions(+) diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittimin= g.c index 0b93900b1dfa..8f82418230ce 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 + * Copyright (c) 2025 Vincent Mailhol */ =20 #include @@ -151,3 +152,65 @@ int can_get_bittiming(const struct net_device *dev, st= ruct can_bittiming *bt, =20 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 =3D netdev_priv(dev); + u32 xl_bit_time_tqmin =3D can_bit_time_tqmin(&priv->xl.data_bittiming); + u32 nom_bit_time_tqmin =3D can_bit_time_tqmin(&priv->bittiming); + u32 pwms_ns =3D can_tqmin_to_ns(pwm->pwms, priv->clock.freq); + u32 pwml_ns =3D 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 >=3D 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) !=3D 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 >=3D 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) !=3D 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; +} diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h index 967d76689c4f..2504fafc72e4 100644 --- a/include/linux/can/bittiming.h +++ b/include/linux/can/bittiming.h @@ -87,6 +87,11 @@ struct can_tdc { u32 tdcf; }; =20 +/* 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 @@ -203,6 +208,10 @@ int can_get_bittiming(const struct net_device *dev, st= ruct can_bittiming *bt, const unsigned int bitrate_const_cnt, struct netlink_ext_ack *extack); =20 +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 * @@ -245,4 +254,17 @@ static inline unsigned int can_bit_time(const struct c= an_bittiming *bt) return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2; } =20 +/* 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 */ --=20 2.51.0