From patchwork Sun Nov 22 22:27:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?J=2E_Neusch=C3=A4fer?= X-Patchwork-Id: 330467 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 175BFC63798 for ; Sun, 22 Nov 2020 22:39:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA2C1208FE for ; Sun, 22 Nov 2020 22:39:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="il21FU6N" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726300AbgKVWjj (ORCPT ); Sun, 22 Nov 2020 17:39:39 -0500 Received: from mout.gmx.net ([212.227.17.21]:33403 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725782AbgKVWji (ORCPT ); Sun, 22 Nov 2020 17:39:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1606084722; bh=57r1xFqwCJIDRPuJ/P+J2+bFfyswaMLpxJDG6pNT6Us=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=il21FU6NF3dQ4rt6xiuQbnpb4ct4m5PMoflxM5Wuy2FeerQEKr56SV1CUJV6VCG+3 FTd6R44Z/tYqsBVuaZczEwSoGXUU0JCM3zSe6pe/T2N2to3641x3kbjr+asB/4A9Yx wAknJwZ6XnaXMATvFWoJ61RjMNPaGyD2NgYxIxew= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from longitude ([37.201.214.162]) by mail.gmx.com (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MmDEm-1jynY22wJk-00iAMf; Sun, 22 Nov 2020 23:38:42 +0100 From: =?utf-8?q?Jonathan_Neusch=C3=A4fer?= To: linux-kernel@vger.kernel.org Cc: Lee Jones , Rob Herring , =?utf-8?q?Jonathan_Neusch=C3=A4fer?= , Thierry Reding , =?utf-8?q?Uwe_Kleine-K?= =?utf-8?b?w7ZuaWc=?= , Alessandro Zummo , Alexandre Belloni , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Sam Ravnborg , Linus Walleij , Heiko Stuebner , Stephan Gerhold , Lubomir Rintel , Mark Brown , allen , Mauro Carvalho Chehab , "David S. Miller" , devicetree@vger.kernel.org, linux-pwm@vger.kernel.org, linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Heiko Stuebner , Josua Mayer , Andreas Kemnade , Arnd Bergmann , Daniel Palmer , Andy Shevchenko Subject: [PATCH v4 4/7] pwm: ntxec: Add driver for PWM function in Netronix EC Date: Sun, 22 Nov 2020 23:27:36 +0100 Message-Id: <20201122222739.1455132-5-j.neuschaefer@gmx.net> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201122222739.1455132-1-j.neuschaefer@gmx.net> References: <20201122222739.1455132-1-j.neuschaefer@gmx.net> MIME-Version: 1.0 X-Provags-ID: V03:K1:EE1AT1+Tqq9NOJEAKqjynManQRn7SWiapiXMkOZaDjPer7g1vLD +b7hMCkvGaVCfpS1E1m/QFWG61Fj7LvKlsV9H0K/IkFpAbkMPqBqDdhfPUzsP5NzpU5zD+g ho1KX0G+QSiz+XMieZQsWQrQVYIdcNH/mvQje10Sn8J1aWZ02d0KQGMP5rHtev4Iky8QO0Q 2aiLHV3Pa3ggEuVEuISQQ== X-UI-Out-Filterresults: notjunk:1; V03:K0:iFDVfCBf8eE=:4yNeNHof8H7GxJsk6MPrJc W/Dp9uZnYGIchuA2N8vPOvZufdQpfXya+qwEqWlfPNoQXVikNkaG1nloDGJ3EsxLUKeSF9+1m JbaFgbhFxcJxA8xbwx4W9yacR0OEfLQzO2QOroqC4jdo3tEOCXGfwnV2MCQLNaLfK87x54xWD rfOvBtyY/xplsst3xQnhedvr2Wz632vSOi+TWZ8EvBPGNi4AjuG9MK3QUbZcpz8TAkz75axEQ qHfZV+iBh9ZWjuH+262oMvkMVLO/z7v6AZdbiBVrQmtUtRrGVHFbvaMB6E1Cw7t0cPLQVLSCq gEKd9DbfGtlLNzEYTFc1rLSUp3QUOiHZh5/m5SZb+l2vmy0KA5CdlnG2x7fmBUu/MZ2J2AGRe eTj//sJx4h+thdavIhDiTXn6owNrs9/azXl+R9i2/Y8M+6URaZdehbgQxdppEMQBYMcsbTtW5 bYhRIdTn7+S6VGtJ8quDKfkYtQfZcJHe6OZsLqrHD0AleR5xDuxCpSDWzV4lcNiRJfmu1uu+K B/kFIRWLgPyoOdhgDedfdj5bvOp9MvM3JdGnf3xgyo+1rpUkgfFeG22CBiYucmaM4iVsVcezX izAb/gO6tYwfuppCWUUjR5JRTxzz4iIXwfJrppNRpwK9r+O5WQymYMkNjsm2kFUhyAxod9yA1 cdbtVe9YBUn9B1bISxGAS49CyvecEUi6YMI2PoK8P1+C8w/PdeoeRl+3wELJnHLO4RbzJ/cRV QtI1WMT3Ut3wAAbpGKP68fc62lEjmADX/vmbohQ10PLGzxpfVQ2kYv4j9cDp/jUGIN7n+oEFh tkXwOINAh4K3AvKyxWFjidypMcNi37LYos0sOUElC/JJgDKrEuBepyAAO4wkA9a8LOwNQCNOZ O60HONLsgD0UTcihTWKw== Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The Netronix EC provides a PWM output which is used for the backlight on some ebook readers. This patches adds a driver for the PWM output. The .get_state callback is not implemented, because the PWM state can't be read back from the hardware. Signed-off-by: Jonathan Neuschäfer --- v4: - Document hardware/driver limitations - Only accept normal polarity - Fix a typo ("zone" -> "zero") - change MAX_PERIOD_NS to 0xffff * 125 - Clamp period to the maximum rather than returning an error - Rename private struct pointer to priv - Rearrage control flow in _probe to save a few lines and a temporary variable - Add missing MODULE_ALIAS line - Spell out ODM v3: - https://lore.kernel.org/lkml/20200924192455.2484005-5-j.neuschaefer@gmx.net/ - Relicense as GPLv2 or later - Add email address to copyright line - Remove OF compatible string and don't include linux/of_device.h - Fix bogus ?: in return line - Don't use a comma after sentinels - Avoid ret |= ... pattern - Move 8-bit register conversion to ntxec.h v2: - https://lore.kernel.org/lkml/20200905133230.1014581-6-j.neuschaefer@gmx.net/ - Various grammar and style improvements, as suggested by Uwe Kleine-König, Lee Jones, and Alexandre Belloni - Switch to regmap - Prefix registers with NTXEC_REG_ - Add help text to the Kconfig option - Use the .apply callback instead of the old API - Add a #define for the time base (125ns) - Don't change device state in .probe; this avoids multiple problems - Rework division and overflow check logic to perform divisions in 32 bits - Avoid setting duty cycle to zero, to work around a hardware quirk --- drivers/pwm/Kconfig | 8 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-ntxec.c | 166 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 175 insertions(+) create mode 100644 drivers/pwm/pwm-ntxec.c -- 2.29.2 diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 63be5362fd3a5..815f329ed5b46 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -350,6 +350,14 @@ config PWM_MXS To compile this driver as a module, choose M here: the module will be called pwm-mxs. +config PWM_NTXEC + tristate "Netronix embedded controller PWM support" + depends on MFD_NTXEC + help + Say yes here if you want to support the PWM output of the embedded + controller found in certain e-book readers designed by the original + design manufacturer Netronix. + config PWM_OMAP_DMTIMER tristate "OMAP Dual-Mode Timer PWM support" depends on OF diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index cbdcd55d69eef..1deb29e6ae8e5 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -32,6 +32,7 @@ obj-$(CONFIG_PWM_MESON) += pwm-meson.o obj-$(CONFIG_PWM_MEDIATEK) += pwm-mediatek.o obj-$(CONFIG_PWM_MTK_DISP) += pwm-mtk-disp.o obj-$(CONFIG_PWM_MXS) += pwm-mxs.o +obj-$(CONFIG_PWM_NTXEC) += pwm-ntxec.o obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o obj-$(CONFIG_PWM_PXA) += pwm-pxa.o diff --git a/drivers/pwm/pwm-ntxec.c b/drivers/pwm/pwm-ntxec.c new file mode 100644 index 0000000000000..4f4f736d71aba --- /dev/null +++ b/drivers/pwm/pwm-ntxec.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * The Netronix embedded controller is a microcontroller found in some + * e-book readers designed by the original design manufacturer Netronix, Inc. + * It contains RTC, battery monitoring, system power management, and PWM + * functionality. + * + * This driver implements PWM output. + * + * Copyright 2020 Jonathan Neuschäfer + * + * Limitations: + * - The get_state callback is not implemented, because the current state of + * the PWM output can't be read back from the hardware. + * - The hardware can only generate normal polarity output. + */ + +#include +#include +#include +#include +#include +#include + +struct ntxec_pwm { + struct device *dev; + struct ntxec *ec; + struct pwm_chip chip; +}; + +static struct ntxec_pwm *pwmchip_to_priv(struct pwm_chip *chip) +{ + return container_of(chip, struct ntxec_pwm, chip); +} + +#define NTXEC_REG_AUTO_OFF_HI 0xa1 +#define NTXEC_REG_AUTO_OFF_LO 0xa2 +#define NTXEC_REG_ENABLE 0xa3 +#define NTXEC_REG_PERIOD_LOW 0xa4 +#define NTXEC_REG_PERIOD_HIGH 0xa5 +#define NTXEC_REG_DUTY_LOW 0xa6 +#define NTXEC_REG_DUTY_HIGH 0xa7 + +/* + * The time base used in the EC is 8MHz, or 125ns. Period and duty cycle are + * measured in this unit. + */ +#define TIME_BASE_NS 125 + +/* + * The maximum input value (in nanoseconds) is determined by the time base and + * the range of the hardware registers that hold the converted value. + * It fits into 32 bits, so we can do our calculations in 32 bits as well. + */ +#define MAX_PERIOD_NS (TIME_BASE_NS * 0xffff) + +static int ntxec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm_dev, + const struct pwm_state *state) +{ + struct ntxec_pwm *priv = pwmchip_to_priv(pwm_dev->chip); + unsigned int duty = state->duty_cycle; + unsigned int period = state->period; + int res = 0; + + if (state->polarity != PWM_POLARITY_NORMAL) + return -EINVAL; + + if (period > MAX_PERIOD_NS) { + period = MAX_PERIOD_NS; + + if (duty > period) + duty = period; + } + + period /= TIME_BASE_NS; + duty /= TIME_BASE_NS; + + res = regmap_write(priv->ec->regmap, NTXEC_REG_PERIOD_HIGH, ntxec_reg8(period >> 8)); + if (res) + return res; + + res = regmap_write(priv->ec->regmap, NTXEC_REG_PERIOD_LOW, ntxec_reg8(period)); + if (res) + return res; + + res = regmap_write(priv->ec->regmap, NTXEC_REG_DUTY_HIGH, ntxec_reg8(duty >> 8)); + if (res) + return res; + + res = regmap_write(priv->ec->regmap, NTXEC_REG_DUTY_LOW, ntxec_reg8(duty)); + if (res) + return res; + + /* + * Writing a duty cycle of zero puts the device into a state where + * writing a higher duty cycle doesn't result in the brightness that it + * usually results in. This can be fixed by cycling the ENABLE register. + * + * As a workaround, write ENABLE=0 when the duty cycle is zero. + */ + if (state->enabled && duty != 0) { + res = regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(1)); + if (res) + return res; + + /* Disable the auto-off timer */ + res = regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_HI, ntxec_reg8(0xff)); + if (res) + return res; + + return regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_LO, ntxec_reg8(0xff)); + } else { + return regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(0)); + } +} + +static struct pwm_ops ntxec_pwm_ops = { + .apply = ntxec_pwm_apply, + .owner = THIS_MODULE, +}; + +static int ntxec_pwm_probe(struct platform_device *pdev) +{ + struct ntxec *ec = dev_get_drvdata(pdev->dev.parent); + struct ntxec_pwm *priv; + struct pwm_chip *chip; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->ec = ec; + priv->dev = &pdev->dev; + + platform_set_drvdata(pdev, priv); + + chip = &priv->chip; + chip->dev = &pdev->dev; + chip->ops = &ntxec_pwm_ops; + chip->base = -1; + chip->npwm = 1; + + return pwmchip_add(chip); +} + +static int ntxec_pwm_remove(struct platform_device *pdev) +{ + struct ntxec_pwm *priv = platform_get_drvdata(pdev); + struct pwm_chip *chip = &priv->chip; + + return pwmchip_remove(chip); +} + +static struct platform_driver ntxec_pwm_driver = { + .driver = { + .name = "ntxec-pwm", + }, + .probe = ntxec_pwm_probe, + .remove = ntxec_pwm_remove, +}; +module_platform_driver(ntxec_pwm_driver); + +MODULE_AUTHOR("Jonathan Neuschäfer "); +MODULE_DESCRIPTION("PWM driver for Netronix EC"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ntxec-pwm");