From patchwork Sun Jan 17 13:17:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Baruch Siach X-Patchwork-Id: 365304 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 12618C433DB for ; Sun, 17 Jan 2021 13:18:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE26B2222B for ; Sun, 17 Jan 2021 13:18:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728982AbhAQNS5 (ORCPT ); Sun, 17 Jan 2021 08:18:57 -0500 Received: from guitar.tcltek.co.il ([192.115.133.116]:52072 "EHLO mx.tkos.co.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728967AbhAQNSx (ORCPT ); Sun, 17 Jan 2021 08:18:53 -0500 Received: from tarshish.tkos.co.il (unknown [10.0.8.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx.tkos.co.il (Postfix) with ESMTPS id 606B8440856; Sun, 17 Jan 2021 15:17:32 +0200 (IST) From: Baruch Siach To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K?= =?utf-8?b?w7ZuaWc=?= , Lee Jones , Linus Walleij , Bartosz Golaszewski Cc: Baruch Siach , Russell King , Andrew Lunn , Gregory Clement , Sebastian Hesselbarth , Thomas Petazzoni , Chris Packham , Sascha Hauer , Ralph Sennhauser , linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 5/5] gpio: mvebu: improve handling of pwm zero on/off values Date: Sun, 17 Jan 2021 15:17:06 +0200 Message-Id: <065aa239ba7e10b64f1c563aba08626f5de790ba.1610882271.git.baruch@tkos.co.il> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org Hardware appears to treat zero value as 2^32. Take advantage of this fact to support on/off values of up to UINT_MAX+1 == 2^32. Adjust both .apply and .get_sate to handle zero as a special case. Rounded up division result in .get_state can't be zero, since the dividend is now larger than 0. Remove check for this case. Reported-by: Uwe Kleine-König Analyzed-by: Russell King Signed-off-by: Baruch Siach --- drivers/gpio/gpio-mvebu.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index 6b017854ce61..37f5bd65062f 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -667,22 +667,20 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip, spin_lock_irqsave(&mvpwm->lock, flags); regmap_read(mvpwm->regs, mvebu_pwmreg_blink_on_duration(mvpwm), &u); - val = (unsigned long long) u * NSEC_PER_SEC; - val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate); - if (val) - state->duty_cycle = val; + /* Hardware treats zero as 2^32. See mvebu_pwm_apply(). */ + if (u > 0) + val = (unsigned long long) u * NSEC_PER_SEC; else - state->duty_cycle = 1; + val = ((unsigned long long) UINT_MAX+1) * NSEC_PER_SEC; + state->duty_cycle = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate); - val = (unsigned long long) u; /* on duration */ regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u); - val += (unsigned long long) u; /* period = on + off duration */ - val *= NSEC_PER_SEC; - val = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate); - if (val) - state->period = val; + /* period = on + off duration */ + if (u > 0) + val += (unsigned long long) u * NSEC_PER_SEC; else - state->period = 1; + val += ((unsigned long long) UINT_MAX+1) * NSEC_PER_SEC; + state->period = DIV_ROUND_UP_ULL(val, mvpwm->clk_rate); regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u); if (u) @@ -704,9 +702,15 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle; do_div(val, NSEC_PER_SEC); - if (val > UINT_MAX) + if (val > (unsigned long long) UINT_MAX+1) return -EINVAL; - if (val) + /* + * Zero on/off values don't work as expected. Experimentation shows + * that zero value is treated as 2^32. This behavior is not documented. + */ + if (val == (unsigned long long) UINT_MAX+1) + on = 0; + else if (val) on = val; else on = 1; @@ -714,9 +718,11 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, val = (unsigned long long) mvpwm->clk_rate * state->period; do_div(val, NSEC_PER_SEC); val -= on; - if (val > UINT_MAX) + if (val > (unsigned long long) UINT_MAX+1) return -EINVAL; - if (val) + if (val == (unsigned long long) UINT_MAX+1) + off = 0; + else if (val) off = val; else off = 1;