From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AEBF1C17460 for ; Tue, 5 Nov 2019 14:57:10 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7E09E21929 for ; Tue, 5 Nov 2019 14:57:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aZHFGH8K" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E09E21929 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=+gRgY8nwEd3PE8sWJ3o/l4uGQczgpwsl19LSslKaZhA=; b=aZHFGH8KoIbGjg 2sPFIaVg9Y2Ezwj+wCvnrPIDKdbdXypQk0vAVc8pxY2lwE9KHrwIb5KxhgCsYsJsvV0Qc3TOA20Rh nLL+XR/63MffykqAjyoYuO2J04tHkrOTBJm7N9D3nQf6BoRqueaJYznolj/gNWD8RE3j2QtIculUc 0NV5nDw57RJaE4yG2ODewFJ+OVeiqvaCoNni0KDcYzsTANGziG+rJ1by9/rYxb54/Vju4krpWVcLn +H2GGKS6GtfEiT7BK1JTZA6nRersDCVrVT+t5605gd4nC/KVaC+CgragQPa8vjryyDyVUiyOstBvV C0o+NEtvOO0nn+T1BCsg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iS0Gb-0004JR-61; Tue, 05 Nov 2019 14:57:09 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iS0GX-0004Ib-HL for linux-arm-kernel@lists.infradead.org; Tue, 05 Nov 2019 14:57:07 +0000 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iS0GS-0000O7-JN; Tue, 05 Nov 2019 15:57:00 +0100 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1iS0GR-0001YE-Ba; Tue, 05 Nov 2019 15:56:59 +0100 Date: Tue, 5 Nov 2019 15:56:59 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: =?iso-8859-1?Q?Cl=E9ment_P=E9ron?= Subject: Re: [PATCH v3 4/7] pwm: sun4i: Add support to output source clock directly Message-ID: <20191105145659.ffezqntodsys4phn@pengutronix.de> References: <20191105131456.32400-1-peron.clem@gmail.com> <20191105131456.32400-5-peron.clem@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191105131456.32400-5-peron.clem@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191105_065705_576152_0E7E4F2E X-CRM114-Status: GOOD ( 24.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , linux-pwm@vger.kernel.org, Jernej Skrabec , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Maxime Ripard , Rob Herring , Chen-Yu Tsai , Thierry Reding , Philipp Zabel , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Nov 05, 2019 at 02:14:53PM +0100, Cl=E9ment P=E9ron wrote: > From: Jernej Skrabec > = > PWM core has an option to bypass whole logic and output unchanged source > clock as PWM output. This is achieved by enabling bypass bit. > = > Note that when bypass is enabled, no other setting has any meaning, not > even enable bit. > = > This mode of operation is needed to achieve high enough frequency to > serve as clock source for AC200 chip which is integrated into same > package as H6 SoC. > = > Signed-off-by: Jernej Skrabec > Signed-off-by: Cl=E9ment P=E9ron > --- > drivers/pwm/pwm-sun4i.c | 38 +++++++++++++++++++++++++++++++++++++- > 1 file changed, 37 insertions(+), 1 deletion(-) > = > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c > index 54e19fa56a4e..810abf47c261 100644 > --- a/drivers/pwm/pwm-sun4i.c > +++ b/drivers/pwm/pwm-sun4i.c > @@ -3,6 +3,10 @@ > * Driver for Allwinner sun4i Pulse Width Modulation Controller > * > * Copyright (C) 2014 Alexandre Belloni > + * > + * Limitations: > + * - When outputing the source clock directly, the PWM logic will be byp= assed > + * and the currently running period is not guaranteed to be completed > */ > = > #include > @@ -73,6 +77,7 @@ static const u32 prescaler_table[] =3D { > = > struct sun4i_pwm_data { > bool has_prescaler_bypass; > + bool has_direct_mod_clk_output; > unsigned int npwm; > }; > = > @@ -118,6 +123,20 @@ static void sun4i_pwm_get_state(struct pwm_chip *chi= p, > = > val =3D sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); > = > + /* > + * PWM chapter in H6 manual has a diagram which explains that if bypass > + * bit is set, no other setting has any meaning. Even more, experiment > + * proved that also enable bit is ignored in this case. > + */ > + if ((val & BIT_CH(PWM_BYPASS, pwm->hwpwm)) && > + sun4i_pwm->data->has_direct_mod_clk_output) { > + state->period =3D DIV_ROUND_UP_ULL(NSEC_PER_SEC, clk_rate); > + state->duty_cycle =3D state->period / 2; Please round up here. > + state->polarity =3D PWM_POLARITY_NORMAL; > + state->enabled =3D true; > + return; > + } > + > if ((PWM_REG_PRESCAL(val, pwm->hwpwm) =3D=3D PWM_PRESCAL_MASK) && > sun4i_pwm->data->has_prescaler_bypass) > prescaler =3D 1; > @@ -203,7 +222,8 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, str= uct pwm_device *pwm, > { > struct sun4i_pwm_chip *sun4i_pwm =3D to_sun4i_pwm_chip(chip); > struct pwm_state cstate; > - u32 ctrl; > + u32 ctrl, clk_rate; > + bool bypass; > int ret; > unsigned int delay_us; > unsigned long now; > @@ -218,6 +238,15 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, st= ruct pwm_device *pwm, > } > } > = > + /* > + * Although it would make much more sense to check for bypass in > + * sun4i_pwm_calculate(), value of bypass bit also depends on "enabled". > + */ > + clk_rate =3D clk_get_rate(sun4i_pwm->clk); clk_get_rate must not be called if the clk might be off. > + bypass =3D state->enabled && > + (state->period * clk_rate >=3D NSEC_PER_SEC) && This is too coarse. With state->period =3D 1000000 this is fulfilled (unless the multiplication overflows). > + (state->duty_cycle * 2 =3D=3D state->period); This is too strict. See my previous mail about how this should be done. If bypass is true (and the hardware support it) you can skip the calculation of the other parameters. > + > spin_lock(&sun4i_pwm->ctrl_lock); > ctrl =3D sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); > = > @@ -265,6 +294,13 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, st= ruct pwm_device *pwm, > ctrl &=3D ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); > } > = > + if (sun4i_pwm->data->has_direct_mod_clk_output) { > + if (bypass) > + ctrl |=3D BIT_CH(PWM_BYPASS, pwm->hwpwm); > + else > + ctrl &=3D ~BIT_CH(PWM_BYPASS, pwm->hwpwm); > + } > + > sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); > = > spin_unlock(&sun4i_pwm->ctrl_lock); Best regards Uwe -- = Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | http://www.pengutronix.de/ | _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel