From patchwork Wed Dec 14 09:53:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Stein X-Patchwork-Id: 634904 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F37F5C4332F for ; Wed, 14 Dec 2022 09:54:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237993AbiLNJy1 (ORCPT ); Wed, 14 Dec 2022 04:54:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238055AbiLNJyA (ORCPT ); Wed, 14 Dec 2022 04:54:00 -0500 Received: from mx1.tq-group.com (mx1.tq-group.com [93.104.207.81]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED18011B; Wed, 14 Dec 2022 01:53:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tq-group.com; i=@tq-group.com; q=dns/txt; s=key1; t=1671011633; x=1702547633; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=gn2uz/l27FEWIkvWQjkXj9Cd5gqzlT+kGDtvIUOrdYs=; b=WGwNCu1YYTaz/8JYOjuV8VeGTeCAWLxtGSBQcfSRnsvZpsf4GSIadA7T Tfb16+LMyUudYOf8fSriOebuL+dnLnV/+5eGGQ0vZzkTq+sG5SejH8ACn vuhQkmt8vx4OYWGvE6FfR9pV+rU1SjpgoQ6h17d53lVayfCFFz6rZqdwQ LJoHdkAoa+N4poKeICpKRBVZv5ouN9xwRdfOfa0/cbI23vqeieW/DIS/D Q5tVYAa/CCsL8lS70npHa55nRZZfWZ4+WfTvyIVFlGH81/m+MfjC1JoW2 M2A8If6tFseQ8NrIgT4auJZannANps4JnupsB3++yV05Cu0dLaIO6cwml g==; X-IronPort-AV: E=Sophos;i="5.96,244,1665439200"; d="scan'208";a="27943177" Received: from unknown (HELO tq-pgp-pr1.tq-net.de) ([192.168.6.15]) by mx1-pgp.tq-group.com with ESMTP; 14 Dec 2022 10:53:48 +0100 Received: from mx1.tq-group.com ([192.168.6.7]) by tq-pgp-pr1.tq-net.de (PGP Universal service); Wed, 14 Dec 2022 10:53:48 +0100 X-PGP-Universal: processed; by tq-pgp-pr1.tq-net.de on Wed, 14 Dec 2022 10:53:48 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tq-group.com; i=@tq-group.com; q=dns/txt; s=key1; t=1671011628; x=1702547628; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=gn2uz/l27FEWIkvWQjkXj9Cd5gqzlT+kGDtvIUOrdYs=; b=YpZmmZZ4jvK3ceXLNnq4lCdvB6Q3mlRna8csrZB8gBgj0gLuhz2ukRQh XdgkDmjnghSWU54gTvMnH6cMsQ1obHH6xmo94/PbE83cHvm6ZHbN3HRvv WZuPixaU9FwRXLa4B3vMNQgFIU5emp6PbBXjaCMaxDTxuhWYJX/6DkSgG JsgEXKIYBHe+SHPVUmSt9SBa9sBFvxpPizJmSQwX8XuBg/561WWhc3kT0 /zJ+jkywMeq1aQGtI4a9to1frZJ6FGk+uW26mDU0LIhZGlYLXh/4C/pVt RCqB/Lxm/QzD37+g0qba1np3KhKsB3LzPWUYiUsK5L63y43xqJhTjsDbK w==; X-IronPort-AV: E=Sophos;i="5.96,244,1665439200"; d="scan'208";a="27943176" Received: from vtuxmail01.tq-net.de ([10.115.0.20]) by mx1.tq-group.com with ESMTP; 14 Dec 2022 10:53:48 +0100 Received: from steina-w.tq-net.de (unknown [10.123.53.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by vtuxmail01.tq-net.de (Postfix) with ESMTPSA id 0FCBB280071; Wed, 14 Dec 2022 10:53:48 +0100 (CET) From: Alexander Stein To: Linus Walleij , Bartosz Golaszewski , Rob Herring , Krzysztof Kozlowski Cc: Alexander Stein , linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, Marek Vasut , Laurent Pinchart Subject: [RFC PATCH v2 2/3] gpio: Add gpio delay driver Date: Wed, 14 Dec 2022 10:53:41 +0100 Message-Id: <20221214095342.937303-3-alexander.stein@ew.tq-group.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221214095342.937303-1-alexander.stein@ew.tq-group.com> References: <20221214095342.937303-1-alexander.stein@ew.tq-group.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org This driver implements a GPIO enable/disable delay. It supports a list of GPIO outputs, which ramp-up/ramp-down delay can be specified at consumer location. The main purpose is to address external, passive delays upon line voltage changes. Signed-off-by: Alexander Stein --- drivers/gpio/Kconfig | 8 ++ drivers/gpio/Makefile | 1 + drivers/gpio/gpio-delay.c | 164 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 173 insertions(+) create mode 100644 drivers/gpio/gpio-delay.c diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index ec7cfd4f52b1..8f1dcbe3fd00 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -1684,6 +1684,14 @@ config GPIO_AGGREGATOR industrial control context, to be operated from userspace using the GPIO chardev interface. +config GPIO_DELAY + tristate "GPIO delay" + help + Say yes here to enable the GPIO delay, which provides a way to + configure platform specific delays for GPIO ramp-up or ramp-down + delays. This can serve the following purposes: + - Open-drain output using an RC filter + config GPIO_LATCH tristate "GPIO latch driver" help diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index 010587025fc8..56b6cbe35248 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -52,6 +52,7 @@ obj-$(CONFIG_GPIO_DA9052) += gpio-da9052.o obj-$(CONFIG_GPIO_DA9055) += gpio-da9055.o obj-$(CONFIG_GPIO_DAVINCI) += gpio-davinci.o obj-$(CONFIG_GPIO_DLN2) += gpio-dln2.o +obj-$(CONFIG_GPIO_DELAY) += gpio-delay.o obj-$(CONFIG_GPIO_DWAPB) += gpio-dwapb.o obj-$(CONFIG_GPIO_EIC_SPRD) += gpio-eic-sprd.o obj-$(CONFIG_GPIO_EM) += gpio-em.o diff --git a/drivers/gpio/gpio-delay.c b/drivers/gpio/gpio-delay.c new file mode 100644 index 000000000000..a91d2ea9a8bc --- /dev/null +++ b/drivers/gpio/gpio-delay.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2022 TQ-Systems GmbH + * Author: Alexander Stein + */ + +#include +#include +#include +#include +#include +#include +#include + +#include "gpiolib.h" + +struct gpio_delay_timing { + unsigned long ramp_up_delay_us; + unsigned long ramp_down_delay_us; +}; + +struct gpio_delay_priv { + struct gpio_chip gc; + struct gpio_descs *input_gpio; + struct gpio_delay_timing *delay_timings; +}; + +static int gpio_delay_get_direction(struct gpio_chip *gc, unsigned int offset) +{ + return GPIO_LINE_DIRECTION_OUT; +} + +static void gpio_delay_set(struct gpio_chip *gc, unsigned int offset, int val) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_desc *gpio_desc = priv->input_gpio->desc[offset]; + const struct gpio_delay_timing *delay_timings; + bool ramp_up; + + gpiod_set_value(gpio_desc, val); + + delay_timings = &priv->delay_timings[offset]; + ramp_up = (!gpiod_is_active_low(gpio_desc) && val) || + (gpiod_is_active_low(gpio_desc) && !val); + + if (ramp_up && delay_timings->ramp_up_delay_us) + udelay(delay_timings->ramp_up_delay_us); + if (!ramp_up && delay_timings->ramp_down_delay_us) + udelay(delay_timings->ramp_down_delay_us); +} + +static void gpio_delay_set_can_sleep(struct gpio_chip *gc, unsigned int offset, int val) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_desc *gpio_desc = priv->input_gpio->desc[offset]; + const struct gpio_delay_timing *delay_timings; + bool ramp_up; + + gpiod_set_value_cansleep(gpio_desc, val); + + delay_timings = &priv->delay_timings[offset]; + ramp_up = (!gpiod_is_active_low(gpio_desc) && val) || + (gpiod_is_active_low(gpio_desc) && !val); + + if (ramp_up && delay_timings->ramp_up_delay_us) + fsleep(delay_timings->ramp_up_delay_us); + if (!ramp_up && delay_timings->ramp_down_delay_us) + fsleep(delay_timings->ramp_down_delay_us); +} + +static int gpio_delay_of_xlate(struct gpio_chip *gc, + const struct of_phandle_args *gpiospec, + u32 *flags) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_delay_timing *timings; + u32 line; + + if (gpiospec->args_count != gc->of_gpio_n_cells) + return -EINVAL; + + line = gpiospec->args[0]; + if (line >= gc->ngpio) + return -EINVAL; + + timings = &priv->delay_timings[line]; + timings->ramp_up_delay_us = gpiospec->args[1]; + timings->ramp_down_delay_us = gpiospec->args[2]; + + return line; +} + +static bool gpio_delay_can_sleep(const struct gpio_delay_priv *priv) +{ + int i; + + for (i = 0; i < priv->input_gpio->ndescs; i++) + if (gpiod_cansleep(priv->input_gpio->desc[i])) + return true; + + return false; +} + +static int gpio_delay_probe(struct platform_device *pdev) +{ + struct gpio_delay_priv *priv; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->input_gpio = devm_gpiod_get_array(&pdev->dev, "input", GPIOD_OUT_LOW); + if (IS_ERR(priv->input_gpio)) + return dev_err_probe(&pdev->dev, PTR_ERR(priv->input_gpio), + "Failed to get input-gpios"); + + priv->delay_timings = devm_kcalloc(&pdev->dev, + priv->input_gpio->ndescs, + sizeof(*priv->delay_timings), + GFP_KERNEL); + if (!priv->delay_timings) + return -ENOMEM; + + if (gpio_delay_can_sleep(priv)) { + priv->gc.can_sleep = true; + priv->gc.set = gpio_delay_set_can_sleep; + } else { + priv->gc.can_sleep = false; + priv->gc.set = gpio_delay_set; + } + + priv->gc.get_direction = gpio_delay_get_direction; + priv->gc.of_xlate = gpio_delay_of_xlate; + priv->gc.of_gpio_n_cells = 3; + priv->gc.ngpio = priv->input_gpio->ndescs; + priv->gc.owner = THIS_MODULE; + priv->gc.base = -1; + priv->gc.parent = &pdev->dev; + + platform_set_drvdata(pdev, priv); + + return devm_gpiochip_add_data(&pdev->dev, &priv->gc, priv); +} + +static const struct of_device_id gpio_delay_ids[] = { + { + .compatible = "gpio-delay", + }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, gpio_delay_ids); + +static struct platform_driver gpio_delay_driver = { + .driver = { + .name = "gpio-delay", + .of_match_table = gpio_delay_ids, + }, + .probe = gpio_delay_probe, +}; +module_platform_driver(gpio_delay_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Alexander Stein "); +MODULE_DESCRIPTION("GPIO delay driver");