From nobody Mon Dec 1 23:03:14 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 99CB5306481 for ; Wed, 26 Nov 2025 10:17:06 +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=1764152228; cv=none; b=J8jMbZJLO/EB/+PhDywVLtotDroQv7qp1/ykN6kZ/P4jp1wuocNKPjA4JWM5XJbGA2A9vUQhEkZ/BBDVMg+T87n1JfYk6ulyXGOLZ/4O++6fS41WW2Fozrz9TS4hLy5HMqypWuFTzV/2A/9I6gGYRWy6/m0v+aoLJd8knNIHCOI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764152228; c=relaxed/simple; bh=02qClV8t/neGzU+Om/CXJdNmGkHB1OpYO0cT6QFVG/0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=sjFN5iwUIuPavZZI/nRCbx8n9RGSGKjqBDubM7Jn0rRrBYeRkG2+ydPeCxqeWvReNYwmvJd87atC5XOw53qruzdxbxoocZm5KdSdfqsl5yci3n4kOrrkLIId660mwJIxffSXrzPQfp6+ZRSRaZRjbMLmLcd0c7vTEGrvuo+W72k= 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-0000RI-Sy; 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-002aSt-0n; 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 047FC4A88DB; Wed, 26 Nov 2025 10:16:51 +0000 (UTC) From: Marc Kleine-Budde Date: Wed, 26 Nov 2025 11:16:11 +0100 Subject: [PATCH can-next v8 10/17] can: calc_bittiming: add PWM calculation 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-v8-10-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=3958; i=mkl@pengutronix.de; h=from:subject:message-id; bh=98I2zj8GmadKTNMoYs3T+0NKfbxclYA5pvAk5/CSRIA=; b=owEBbQGS/pANAwAKAQx0Zd/5kJGcAcsmYgBpJtODxuTQ1ocj4WsaZ4Y4pDVGZYITY+t5NEb3E 9RYNfm068WJATMEAAEKAB0WIQSf+wzYr2eoX/wVbPMMdGXf+ZCRnAUCaSbTgwAKCRAMdGXf+ZCR nKjxB/43g3Zud+xW093dn7hsyzJ3zCF7xERL0bi1g8eN4ttw4b9u5Xur1ujVNN+Sdt1FLCM0zV+ FiL7skAf967m6OBMbSq+Db3e7jVdv0vsK6QuEw8GUZQYquEW9x/f7cDnc4omtJI6nP4PFRfkeR1 L6K+70z3E1TJBWlyi7vYPs7/0QG7gfJEy4KhStawrQnc3XECqr5f9XDQwWXc7jI3R1J1CxAgIUT enbRzS1XKFosM7FuHhqJwdTKKr1AGcnboz22BoXStLpayzXN6qSNxy3zzBJ6Jmsb0xE4EMOn7il 9PbZsAcIcyIJ7C/OyHXShCGY4qvnXn+DJDAaQQe//LPg5IlS 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 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 Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev/calc_bittiming.c | 36 ++++++++++++++++++++++++++++++++= ++++ include/linux/can/bittiming.h | 10 ++++++++++ 2 files changed, 46 insertions(+) diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/cal= c_bittiming.c index 394d6974f481..268ec6fa7c49 100644 --- a/drivers/net/can/dev/calc_bittiming.c +++ b/drivers/net/can/dev/calc_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) 2021-2025 Vincent Mailhol */ =20 #include @@ -198,3 +199,38 @@ void can_calc_tdco(struct can_tdc *tdc, const struct c= an_tdc_const *tdc_const, *ctrlmode |=3D tdc_auto; } } + +int can_calc_pwm(struct net_device *dev, struct netlink_ext_ack *extack) +{ + struct can_priv *priv =3D netdev_priv(dev); + const struct can_pwm_const *pwm_const =3D priv->xl.pwm_const; + struct can_pwm *pwm =3D &priv->xl.pwm; + u32 xl_tqmin =3D can_bit_time_tqmin(&priv->xl.data_bittiming); + u32 xl_ns =3D can_tqmin_to_ns(xl_tqmin, priv->clock.freq); + u32 nom_tqmin =3D can_bit_time_tqmin(&priv->bittiming); + int pwm_per_bit_max =3D xl_tqmin / (pwm_const->pwms_min + pwm_const->pwml= _min); + int pwm_per_bit; + u32 pwm_tqmin; + + /* For 5 MB/s databitrate or greater, xl_ns < CAN_PWM_NS_MAX + * giving us a pwm_per_bit of 1 and the loop immediately breaks + */ + for (pwm_per_bit =3D DIV_ROUND_UP(xl_ns, CAN_PWM_NS_MAX); + pwm_per_bit <=3D pwm_per_bit_max; pwm_per_bit++) + if (xl_tqmin % pwm_per_bit =3D=3D 0) + break; + + if (pwm_per_bit > pwm_per_bit_max) { + NL_SET_ERR_MSG_FMT(extack, + "Can not divide the XL data phase's bit time: %u tqmin into multipl= e PWM symbols", + xl_tqmin); + return -EINVAL; + } + + pwm_tqmin =3D xl_tqmin / pwm_per_bit; + pwm->pwms =3D DIV_ROUND_UP_POW2(pwm_tqmin, 4); + pwm->pwml =3D pwm_tqmin - pwm->pwms; + pwm->pwmo =3D nom_tqmin % pwm_tqmin; + + return 0; +} diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h index 2504fafc72e4..726d909e87ce 100644 --- a/include/linux/can/bittiming.h +++ b/include/linux/can/bittiming.h @@ -180,6 +180,8 @@ int can_calc_bittiming(const struct net_device *dev, st= ruct can_bittiming *bt, void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_co= nst, 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, @@ -195,6 +197,14 @@ can_calc_tdco(struct can_tdc *tdc, const struct can_td= c_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 */ =20 void can_sjw_set_default(struct can_bittiming *bt); --=20 2.51.0