Messages in this thread | | | Subject | Re: [PATCH 05/10] hwmon: generic-pwm-tachometer: Add generic PWM based tachometer | From | Rajkumar Rampelli <> | Date | Wed, 28 Feb 2018 11:42:28 +0530 |
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On Wednesday 28 February 2018 11:28 AM, Guenter Roeck wrote: > On 02/27/2018 09:38 PM, Rajkumar Rampelli wrote: >> >> 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 <rrajk@nvidia.com> >>>> --- >>>> 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 <rrajk@nvidia.com> >>>> + >>>> +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 <linux/module.h> >>>> +#include <linux/platform_device.h> >>>> +#include <linux/err.h> >>>> +#include <linux/pwm.h> >>>> +#include <linux/hwmon.h> >>>> +#include <linux/hwmon-sysfs.h> >>>> + >>>> +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 { > > Are you kidding me ? > > Guenter Sorry, I just wanted to confirm whether my understanding is correct or not before implementing it actually. Or, shall I add this attribute as a part of fan attributes with "hwmon_fan_rpm" ? or any other way to do it ? I need your inputs in fixing this.
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