From patchwork Sat Sep 5 13:32:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Jonathan_Neusch=C3=A4fer?= X-Patchwork-Id: 1358033 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-rtc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=gmx.net Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=gmx.net header.i=@gmx.net header.a=rsa-sha256 header.s=badeba3b8450 header.b=PZZAz0sW; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BkGG25cy7z9sTM for ; Sat, 5 Sep 2020 23:52:57 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728703AbgIENwy (ORCPT ); Sat, 5 Sep 2020 09:52:54 -0400 Received: from mout.gmx.net ([212.227.15.15]:39023 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728585AbgIENg1 (ORCPT ); Sat, 5 Sep 2020 09:36:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1599312876; bh=NYuBBLNYiGIhFA8o9V2DO+rgKTITXVswEb0z0J0XHbQ=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=PZZAz0sWRcfz36991DP8m6xp3eKauhXE0K4YfzOn+5QIZBC90lhhZDJG1nKjqtzTK p6b+ujbvUAxEabLeXQbGQwXYQ51UjtfS+dAX+gVqZnVTNIA/Vx6DxkPcLbqTN9JWIO bfSOsbcnupi2poRxHd9JqGb9YfRvcgC5mu2txxSQ= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from longitude ([5.146.195.151]) by mail.gmx.com (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MFbRs-1kLjKk2AD0-00H3tl; Sat, 05 Sep 2020 15:34:36 +0200 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=C3=B6nig?= , 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 Subject: [PATCH v2 05/10] pwm: ntxec: Add driver for PWM function in Netronix EC Date: Sat, 5 Sep 2020 15:32:25 +0200 Message-Id: <20200905133230.1014581-6-j.neuschaefer@gmx.net> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200905133230.1014581-1-j.neuschaefer@gmx.net> References: <20200905133230.1014581-1-j.neuschaefer@gmx.net> MIME-Version: 1.0 X-Provags-ID: V03:K1:5pnqftFZLWVKcseh85w/XixgLxNOAvblrI3RkgnBGCnWbcUdOQO oR6pTp5i1i9KRv6AEMAEDIyzQAlJojtBLaPfURJpdu1/0ASyla0RXdIjvkOFjaP4sc3LlJ8 xJh02xjBlZutvFYchDqsCsNhLQrB5vxUZosPqH6NoGqqqXBqmBv/M0bZA8KktA2q35/a5tA iCf1U3MUMlRq4AH+juyPw== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:cf/EYcs42qM=:Litgd/tjvyuyvzxMu1YSS2 fLvKl54JHoKIZ1yz5yGT8zsafFeUBLXMsLyAwwPQ1iOg4nVSfvmt1/RcORbHMgwrfAqvftoV9 J3Yv+phuDNvr75ci2KGj/034Ok1MbTwUSHKWMfEaoMPvsV+Hof1cu/UU5FO5Po6MqsSYT02OE z7TDap1Uo+0ZPUXfuMJbvPdF7YCo64VWmWlv/MQOXS2/vSR0ZqEHNloPxnmSVTobSJEoXHIGu 8zctdgQs0SkKbxtTJmv/uJi9cyOU5WzDd9udffMShAnOkV22w/nsBFX6Jg3pnZbkuqfb6eVlN 83Uudbkx08QoY4ieXs3aVt9OSHylJnj7ggKBnUR0W5U5L6kZzaeies/ffCvqCiQYAfjnmvMHz Fq9WIAZxhjP92fvAddD8VfvvlF/oXgfmAj+1TYzPiT1lXU/fj1QeoFVZv9XMAqUWVprs7d0pb nwd5vaCf+SyTW5JtDFtp7y0uZaJf4+sWsce87DnLMCLYLA92Tqv2h025DjC3ZCusjxP2HjKa6 3PLrghEwkGsbeerM+SeLDPmnbcO/Qw2mJteHVG6NJGaWr4iFa630RzEnDqvT0ZIaBzjLSB7kU KHzjYDh+UOcVPdf0Wx5P0dXKxIHOcY7Q6G0NGmd3OROAJtaD/pA66L2jXGnhWOTC+zrK5z9Kx klK8TreMmie5KAyJdgDimR4Xh2JmtWLR4fyggCzLNdzbPeTfC8VGbUFcJei54Lc6jcZ1N6LY/ hsLpMLjbYCP58rM5Vz11THQEhvCV2eod5Ca1UlEROJMOHOgeGzeBRfmSVAy5hZwVl362qwVMN INdHDDqHMt3GDVgkeMqsCjwgq/IwsCqVZE+zRo84i6FvckQ1G5f5CZwb2odoH+mQS9Mpu6ZX4 Gq7mqzj0j+DbEiCy0PGWN6TCnJHhpamvBffkkmuEH8/175wX62wfgZ6WDeDF5nVTL11n4igLK TrV4xWY/9TI3EgnZH8LSqXg51VnNGGMTqQWh31Vx/qVZVwPfGNV4Pez4ZEfRuNwI5R6j72NlF l3moxh8K5MQZ0OMKQ8MKONtT6nUs/AuR0E+LYhB3YDH6ixGDqas4WEK5C+xs58w0bQ3HELsG4 mxnMPP8i793R3UI0OatXaaf+FdOMil+QGbReqxvY+JpvVD3fFjCYXAgXlf4GfxA0Dtd16uyVJ YfGjX3iscSx7JKYYXWJ/P2XBbIFkhtd4mTbN7g2SRNRbkh19ppqw7nwQ4vMJhzTnqDiVfKn2I c4kGV/RCiw6PquXi36muUXOT19y2In45ftIAsbQ== Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@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. Signed-off-by: Jonathan Neuschäfer --- v2: - 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 | 160 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 169 insertions(+) create mode 100644 drivers/pwm/pwm-ntxec.c -- 2.28.0 diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 7dbcf6973d335..7fd17c6cda95e 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 && OF + 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 ODM + 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 2c2ba0a035577..1cc50dba22d1b 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..325ec0e8f1996 --- /dev/null +++ b/drivers/pwm/pwm-ntxec.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * The Netronix embedded controller is a microcontroller found in some + * e-book readers designed by the ODM Netronix, Inc. It contains RTC, + * battery monitoring, system power management, and PWM functionality. + * + * This driver implements PWM output. + * + * Copyright 2020 Jonathan Neuschäfer + */ + +#include +#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_pwm(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 + +/* Convert an 8-bit value into the correct format for writing into a register */ +#define u8_to_reg(x) (((x) & 0xff) << 8) + +/* + * 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 * 0x10000 - 1) + +static int ntxec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm_dev, + const struct pwm_state *state) +{ + struct ntxec_pwm *pwm = pwmchip_to_pwm(pwm_dev->chip); + unsigned int duty = state->duty_cycle; + unsigned int period = state->period; + int res = 0; + + if (period > MAX_PERIOD_NS) { + dev_warn(pwm->dev, + "Period is not representable in 16 bits after division by %u: %u\n", + TIME_BASE_NS, period); + return -ERANGE; + } + + period /= TIME_BASE_NS; + duty /= TIME_BASE_NS; + + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_PERIOD_HIGH, u8_to_reg(period >> 8)); + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_PERIOD_LOW, u8_to_reg(period)); + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_DUTY_HIGH, u8_to_reg(duty >> 8)); + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_DUTY_LOW, u8_to_reg(duty)); + + if (res < 0) + return -EIO; + + /* + * Writing a duty cycle of zone 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(pwm->ec->regmap, NTXEC_REG_ENABLE, u8_to_reg(1)); + + /* Disable the auto-off timer */ + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_AUTO_OFF_HI, u8_to_reg(0xff)); + res |= regmap_write(pwm->ec->regmap, NTXEC_REG_AUTO_OFF_LO, u8_to_reg(0xff)); + return res ? -EIO : 0; + } else { + return regmap_write(pwm->ec->regmap, NTXEC_REG_ENABLE, u8_to_reg(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 *pwm; + struct pwm_chip *chip; + int res; + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (!pwm) + return -ENOMEM; + + pwm->ec = ec; + pwm->dev = &pdev->dev; + + chip = &pwm->chip; + chip->dev = &pdev->dev; + chip->ops = &ntxec_pwm_ops; + chip->base = -1; + chip->npwm = 1; + + res = pwmchip_add(chip); + if (res < 0) + return res; + + platform_set_drvdata(pdev, pwm); + + return (res < 0) ? -EIO : 0; +} + +static int ntxec_pwm_remove(struct platform_device *pdev) +{ + struct ntxec_pwm *pwm = platform_get_drvdata(pdev); + struct pwm_chip *chip = &pwm->chip; + + return pwmchip_remove(chip); +} + +static const struct of_device_id ntxec_pwm_of_match[] = { + { .compatible = "netronix,ntxec-pwm" }, + { }, +}; +MODULE_DEVICE_TABLE(of, ntxec_pwm_of_match); + +static struct platform_driver ntxec_pwm_driver = { + .driver = { + .name = "ntxec-pwm", + .of_match_table = ntxec_pwm_of_match, + }, + .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");