From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtHxAHFyaxA57duT+Qc2G8LcGLv0zfEo0Q0GDrSw+Xzr35nwBSxoJDHFjAhvtfCubpVcOP+ ARC-Seal: i=1; a=rsa-sha256; t=1519796306; cv=none; d=google.com; s=arc-20160816; b=f1a/b8IPeq0lw6sERXcARirIVnI6s/Jyk4iuhpRVJyeiVbrSAFZQnmEKHv8M2PUWfk xlC5to9XLhUTIUeMfyf2VJ/48V68JXcjYHfrzwr7V1Oe8YhJFUuPf/02COuZnEGYVYVG G/4sepjeGB2977zaA5DGPjTomWP3ex4GDogrDUc6slHvipPAQRzHoYWkTM3MvKN0gTdn ibiNTwAQxAE2tnMK4tkAUcUJQ+qOV9HUGd1mDayrmSQJbpLahnF243ZZiQYyn7iZI6vj 2BzOVtmLYQ+qJwFJXELSBIQMkp+bZ6C15WKOwm6buo06bOT2MGt/TzDGEVGGUpIuPVOp a0Lg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:in-reply-to:mime-version:user-agent:date :message-id:from:cc:references:to:subject:arc-authentication-results; bh=9+bsfOeUu2sa0CGqolOLfZIBG6srp9dXVkTqxOOYT1c=; b=CSt7aTqzWkzpCytu8GL1YMxkeCw/wTAejfnzmhAKKEmM9smmFNslk9sIyjpPAPekou MZb1LQYGrR7mOqDx6+DhqVeHzxFYKW608bB2Qa5YSl51krLeVfbRkUODyhwhDarGLccr 77rkLghbQ1P1S6b6wBc1+gyAIqZzyPIVpP/cgsJP08+F/5McdWYbxVx67Nt9YPMYmIv2 XQoivP1Vwhp6C4fMi68y4ApFFRVIw/a5yaGmcPd7cFE7k15wVrCy/4IjRFMznylEd1qa zGdKGjb2aDJj5nl1GGIhgl+RIoRlBZ2PBw2e5NXR/QdXWWk0Ph86oTSbzGypBFqVy8U/ I7qw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of rrajk@nvidia.com designates 216.228.121.65 as permitted sender) smtp.mailfrom=rrajk@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of rrajk@nvidia.com designates 216.228.121.65 as permitted sender) smtp.mailfrom=rrajk@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 27 Feb 2018 21:38:25 -0800 Subject: Re: [PATCH 05/10] hwmon: generic-pwm-tachometer: Add generic PWM based tachometer To: Guenter Roeck , , , , , , , , , , , , , , , , , , , , , References: <1519196339-9377-1-git-send-email-rrajk@nvidia.com> <1519196339-9377-6-git-send-email-rrajk@nvidia.com> <5172edff-fe29-7ed1-f0d2-b0359ea2c24d@roeck-us.net> CC: , , , , , , , From: Rajkumar Rampelli Message-ID: <2510b525-ec36-b49d-5a62-81f335c0d10d@nvidia.com> Date: Wed, 28 Feb 2018 11:08:20 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <5172edff-fe29-7ed1-f0d2-b0359ea2c24d@roeck-us.net> X-Originating-IP: [10.19.65.123] X-ClientProxiedBy: BGMAIL102.nvidia.com (10.25.59.11) To bgmail103.nvidia.com (10.25.59.12) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1592992898629636853?= X-GMAIL-MSGID: =?utf-8?q?1593621931819616212?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wednesday 21 February 2018 08:20 PM, Guenter Roeck wrote: > On 02/20/2018 10:58 PM, Rajkumar Rampelli wrote: >> Add generic PWM based tachometer driver via HWMON interface >> to report the RPM of motor. This drivers get the period/duty >> cycle from PWM IP which captures the motor PWM output. >> >> This driver implements a simple interface for monitoring the speed of >> a fan and exposes it in roatations per minute (RPM) to the user space >> by using the hwmon's sysfs interface >> >> Signed-off-by: Rajkumar Rampelli >> --- >> Documentation/hwmon/generic-pwm-tachometer | 17 +++++ >> drivers/hwmon/Kconfig | 10 +++ >> drivers/hwmon/Makefile | 1 + >> drivers/hwmon/generic-pwm-tachometer.c | 112 >> +++++++++++++++++++++++++++++ >> 4 files changed, 140 insertions(+) >> create mode 100644 Documentation/hwmon/generic-pwm-tachometer >> create mode 100644 drivers/hwmon/generic-pwm-tachometer.c >> >> diff --git a/Documentation/hwmon/generic-pwm-tachometer >> b/Documentation/hwmon/generic-pwm-tachometer >> new file mode 100644 >> index 0000000..e0713ee >> --- /dev/null >> +++ b/Documentation/hwmon/generic-pwm-tachometer >> @@ -0,0 +1,17 @@ >> +Kernel driver generic-pwm-tachometer >> +==================================== >> + >> +This driver enables the use of a PWM module to monitor a fan. It >> uses the >> +generic PWM interface and can be used on SoCs as along as the SoC >> supports >> +Tachometer controller that moniors the Fan speed in periods. >> + >> +Author: Rajkumar Rampelli >> + >> +Description >> +----------- >> + >> +The driver implements a simple interface for monitoring the Fan >> speed using >> +PWM module and Tachometer controller. It requests period value >> through PWM >> +capture interface to Tachometer and measures the Rotations per >> minute using >> +received period value. It exposes the Fan speed in RPM to the user >> space by >> +using the hwmon's sysfs interface. >> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig >> index ef23553..8912dcb 100644 >> --- a/drivers/hwmon/Kconfig >> +++ b/drivers/hwmon/Kconfig >> @@ -1878,6 +1878,16 @@ config SENSORS_XGENE >> If you say yes here you get support for the temperature >> and power sensors for APM X-Gene SoC. >> +config GENERIC_PWM_TACHOMETER >> + tristate "Generic PWM based tachometer driver" >> + depends on PWM >> + help >> + Enables a driver to use PWM signal from motor to use >> + for measuring the motor speed. The RPM is captured by >> + PWM modules which has PWM capture capability and this >> + drivers reads the captured data from PWM IP to convert >> + it to speed in RPM. >> + >> if ACPI >> comment "ACPI drivers" >> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile >> index f814b4a..9dcc374 100644 >> --- a/drivers/hwmon/Makefile >> +++ b/drivers/hwmon/Makefile >> @@ -175,6 +175,7 @@ obj-$(CONFIG_SENSORS_WM8350) += wm8350-hwmon.o >> obj-$(CONFIG_SENSORS_XGENE) += xgene-hwmon.o >> obj-$(CONFIG_PMBUS) += pmbus/ >> +obj-$(CONFIG_GENERIC_PWM_TACHOMETER) += generic-pwm-tachometer.o >> ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG >> diff --git a/drivers/hwmon/generic-pwm-tachometer.c >> b/drivers/hwmon/generic-pwm-tachometer.c >> new file mode 100644 >> index 0000000..9354d43 >> --- /dev/null >> +++ b/drivers/hwmon/generic-pwm-tachometer.c >> @@ -0,0 +1,112 @@ >> +/* >> + * Copyright (c) 2017-2018, NVIDIA CORPORATION. All rights reserved. >> + * >> + * This program is free software; you can redistribute it and/or >> modify it >> + * under the terms and conditions of the GNU General Public License, >> + * version 2, as published by the Free Software Foundation. >> + * >> + * This program is distributed in the hope it will be useful, but >> WITHOUT >> + * ANY WARRANTY; without even the implied warranty of >> MERCHANTABILITY or >> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public >> License for >> + * more details. >> + * >> + */ >> + >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +struct pwm_hwmon_tach { >> + struct device *dev; >> + struct pwm_device *pwm; >> + struct device *hwmon; >> +}; >> + >> +static ssize_t show_rpm(struct device *dev, struct device_attribute >> *attr, >> + char *buf) >> +{ >> + struct pwm_hwmon_tach *ptt = dev_get_drvdata(dev); >> + struct pwm_device *pwm = ptt->pwm; >> + struct pwm_capture result; >> + int err; >> + unsigned int rpm = 0; >> + >> + err = pwm_capture(pwm, &result, 0); >> + if (err < 0) { >> + dev_err(ptt->dev, "Failed to capture PWM: %d\n", err); >> + return err; >> + } >> + >> + if (result.period) >> + rpm = DIV_ROUND_CLOSEST_ULL(60ULL * NSEC_PER_SEC, >> + result.period); >> + >> + return sprintf(buf, "%u\n", rpm); >> +} >> + >> +static SENSOR_DEVICE_ATTR(rpm, 0444, show_rpm, NULL, 0); >> + >> +static struct attribute *pwm_tach_attrs[] = { >> + &sensor_dev_attr_rpm.dev_attr.attr, >> + NULL, >> +}; > > "rpm" is not a standard hwmon sysfs attribute. If you don't provide > a single standard hwmon sysfs attribute, having a hwmon driver is > pointless. Guenter Roeck, I will define a new hwmon sysfs attribute node called "hwmon_tachometer_attributes" in hwmon.h like below and update the same in tachometer hwmon driver. Is it fine ? enum hwmon_tachometer_attributes { hwmon_tachometer_rpm, }; >> + >> +ATTRIBUTE_GROUPS(pwm_tach); >> + >> +static int pwm_tach_probe(struct platform_device *pdev) >> +{ >> + struct pwm_hwmon_tach *ptt; >> + int err; >> + >> + ptt = devm_kzalloc(&pdev->dev, sizeof(*ptt), GFP_KERNEL); >> + if (!ptt) >> + return -ENOMEM; >> + >> + ptt->dev = &pdev->dev; >> + >> + platform_set_drvdata(pdev, ptt); >> + dev_set_drvdata(&pdev->dev, ptt); >> + > > None of those is used. I will take care in next version of patches. > >> + ptt->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL); >> + if (IS_ERR(ptt->pwm)) { >> + err = PTR_ERR(ptt->pwm); >> + dev_err(&pdev->dev, "Failed to get pwm handle, err: %d\n", >> + err); >> + return err; >> + } >> + >> + ptt->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, >> + "pwm_tach", ptt, pwm_tach_groups); > > Please use the new API - devm_hwmon_device_register_with_info - > for new drivers. Sure, will take care. > >> + if (IS_ERR(ptt->hwmon)) { >> + err = PTR_ERR_OR_ZERO(ptt->hwmon); >> + dev_err(&pdev->dev, "Failed to register hwmon device: %d\n", >> + err); >> + return err; >> + } > > Please no noise on failure. The failure is going to be a memory > allocation failure, > which is reported already, and user space will be informed with the > error code. I will take care.