From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3E62E306D58; Mon, 13 Oct 2025 11:02:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760353350; cv=none; b=fCqGMJCQknQfOW5jrgOUA+E7W0FQO6FYhgf8vImDlinLBYgjOY80wz7wDU6uB1lKsghwAKmVVRiZB5TwOVbvHim5JOvqaZVC7tO0yqdMdc7lAnfl2mwdiKO//K67u7Mts9lqVT+TmBLtHdVbY2ajK2XoC+CVeeDwpmAI14zKwaQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760353350; c=relaxed/simple; bh=lGub19npbHTCvhVB1cTDqpyNm/UO+W35qNItTyIqyiM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Uso28pNrrs7/hwZo/GImpumf1rffFBrsqWjRIBAO3f/d/aoC3hP7sH6+iW5Uo9NotzYw3WBIbeI/Gmm+PCjS0rPP95Ix8m3aLh1eVVOi1jwZ5Udigsnb/uAGGusjmw8oSRMLgcRlWL6FEICdqCz2EEssxNAB//GadqFRHGvBKIM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FycjzVD0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FycjzVD0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 796EEC4CEF8; Mon, 13 Oct 2025 11:02:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760353349; bh=lGub19npbHTCvhVB1cTDqpyNm/UO+W35qNItTyIqyiM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=FycjzVD0eNNXQZo05/P/dZnvY0utLz+zz9v7hI0NWjR/MIc06IMq2/vOTURQkJZCv X+5Gm4ADThntk1IaCmU9ehKeq6gpn6sZmTT46DeRwG1AiBS6DKYzPKzAjbL/eADruC xO4osJX85eJ4dEv5wPCHszHfZQYyHiC0MPTW7rEza9rk3YHbjnYdmAx53tr3CNtPK8 oXH7qjiO46dsJ1LkYCuuA6OCsqtc14eZYksT6a1PZ3MQEIJ4/zCYSCXHLm7HVm6sGv yk5x5lu0J/icII5oB4s9hSE2ncmIxUKsf5PdhShRCEYnoYke1rMbKv0Dola98FdJZK oyC0N6b2tFEyg== From: Vincent Mailhol Date: Mon, 13 Oct 2025 20:01:30 +0900 Subject: [PATCH 8/9] can: calc_bittiming: add PWM calculation Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251013-canxl-netlink-v1-8-f422b7e2729f@kernel.org> References: <20251013-canxl-netlink-v1-0-f422b7e2729f@kernel.org> In-Reply-To: <20251013-canxl-netlink-v1-0-f422b7e2729f@kernel.org> To: Marc Kleine-Budde , Oliver Hartkopp Cc: Vincent Mailhol , =?utf-8?q?St=C3=A9phane_Grosjean?= , Robert Nawrath , Minh Le , Duy Nguyen , linux-can@vger.kernel.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3712; i=mailhol@kernel.org; h=from:subject:message-id; bh=lGub19npbHTCvhVB1cTDqpyNm/UO+W35qNItTyIqyiM=; b=owGbwMvMwCV2McXO4Xp97WbG02pJDBlv7hhW172ZwaZavGDOXvOq4H9PmH/fEeeT6WYwXiBuE aKaPCu+o5SFQYyLQVZMkWVZOSe3Qkehd9ihv5Ywc1iZQIYwcHEKwEQesTL8T775lmlRuuPlXsfJ S9+2zeRbWmkf+H7Vh4QjE7/sfx/pnsvwm9XlOsPxnFf3pIID63qiH2/gU3nMHPBjqwv//LXPfnu v4gUA X-Developer-Key: i=mailhol@kernel.org; a=openpgp; fpr=ED8F700574E67F20E574E8E2AB5FEB886DBB99C2 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 --- drivers/net/can/dev/calc_bittiming.c | 36 ++++++++++++++++++++++++++++++++++++ include/linux/can/bittiming.h | 7 +++++++ 2 files changed, 43 insertions(+) diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_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 */ #include @@ -198,3 +199,38 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const, *ctrlmode |= tdc_auto; } } + +int can_calc_pwm(struct net_device *dev, struct netlink_ext_ack *extack) +{ + struct can_priv *priv = netdev_priv(dev); + const struct can_pwm_const *pwm_const = priv->xl.pwm_const; + struct can_pwm *pwm = &priv->xl.pwm; + u32 xl_tqmin = can_bit_time_tqmin(&priv->xl.data_bittiming); + u32 xl_ns = can_tqmin_to_ns(xl_tqmin, priv->clock.freq); + u32 nom_tqmin = can_bit_time_tqmin(&priv->bittiming); + int pwm_per_bit_max = 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 = DIV_ROUND_UP(xl_ns, CAN_PWM_NS_MAX); + pwm_per_bit <= pwm_per_bit_max; pwm_per_bit++) + if (xl_tqmin % pwm_per_bit == 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 multiple PWM symbols", + xl_tqmin); + return -EINVAL; + } + + pwm_tqmin = xl_tqmin / pwm_per_bit; + pwm->pwms = DIV_ROUND_UP_POW2(pwm_tqmin, 4); + pwm->pwml = pwm_tqmin - pwm->pwms; + pwm->pwmo = nom_tqmin % pwm_tqmin; + + return 0; +} diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h index 02cf9541a1dd..e7671a86afcc 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, 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, @@ -195,6 +197,11 @@ 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) +{ +} #endif /* CONFIG_CAN_CALC_BITTIMING */ void can_sjw_set_default(struct can_bittiming *bt); -- 2.49.1