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 11:08:20 +0530 |
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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 { 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.
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