From patchwork Wed Jan 20 16:16:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Baruch Siach X-Patchwork-Id: 1429306 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DLW2W6lxmz9sVS for ; Thu, 21 Jan 2021 03:20:03 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391386AbhATQT2 (ORCPT ); Wed, 20 Jan 2021 11:19:28 -0500 Received: from guitar.tcltek.co.il ([192.115.133.116]:55123 "EHLO mx.tkos.co.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391507AbhATQRk (ORCPT ); Wed, 20 Jan 2021 11:17:40 -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 DC4A2440DAA; Wed, 20 Jan 2021 18:16:41 +0200 (IST) From: Baruch Siach To: Thierry Reding , =?utf-8?q?Uwe_Kleine-K=C3=B6n?= =?utf-8?q?ig?= , 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 v5 4/4] gpio: mvebu: improve handling of pwm zero on/off values Date: Wed, 20 Jan 2021 18:16:28 +0200 Message-Id: X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pwm@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_state 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 Reviewed-by: Uwe Kleine-König --- drivers/gpio/gpio-mvebu.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c index 6b017854ce61..75e3c235bd3a 100644 --- a/drivers/gpio/gpio-mvebu.c +++ b/drivers/gpio/gpio-mvebu.c @@ -667,22 +667,21 @@ 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 = u; else - state->duty_cycle = 1; + val = UINT_MAX + 1ULL; + state->duty_cycle = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC, + 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 += u; else - state->period = 1; + val += UINT_MAX + 1ULL; + state->period = DIV_ROUND_UP_ULL(val * NSEC_PER_SEC, mvpwm->clk_rate); regmap_read(mvchip->regs, GPIO_BLINK_EN_OFF + mvchip->offset, &u); if (u) @@ -704,9 +703,15 @@ 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 > UINT_MAX + 1ULL) 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 == UINT_MAX + 1ULL) + on = 0; + else if (val) on = val; else on = 1; @@ -714,9 +719,11 @@ 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 > UINT_MAX + 1ULL) return -EINVAL; - if (val) + if (val == UINT_MAX + 1ULL) + off = 0; + else if (val) off = val; else off = 1;