Messages in this thread | | | Subject | Re: [PATCH 05/10] hwmon: generic-pwm-tachometer: Add generic PWM based tachometer | From | Guenter Roeck <> | Date | Tue, 27 Feb 2018 21:58:16 -0800 |
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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
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