| Message ID | 1521607244-29734-1-git-send-email-rrajk@nvidia.com |
|---|---|
| Headers | show |
| Series | Implementation of Tegra Tachometer driver | expand |
On 03/20/2018 09:40 PM, Rajkumar Rampelli wrote: > Add fan device attribute fan1_input in pwm-fan driver > to read speed of fan in rotations per minute. > > Signed-off-by: Rajkumar Rampelli <rrajk@nvidia.com> > --- > > V2: Removed generic-pwm-tachometer driver and using pwm-fan driver as per suggestions > to read fan speed. > Added fan device attribute to report speed of fan in rpms through hwmon sysfs. > > drivers/hwmon/pwm-fan.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c > index 70cc0d1..8dda209 100644 > --- a/drivers/hwmon/pwm-fan.c > +++ b/drivers/hwmon/pwm-fan.c > @@ -98,11 +98,34 @@ static ssize_t show_pwm(struct device *dev, > return sprintf(buf, "%u\n", ctx->pwm_value); > } > > +static ssize_t show_rpm(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct pwm_fan_ctx *ptt = dev_get_drvdata(dev); > + struct pwm_device *pwm = ptt->pwm; > + struct pwm_capture result; > + unsigned int rpm = 0; > + int ret; > + > + ret = pwm_capture(pwm, &result, 0); > + if (ret < 0) { > + pr_err("Failed to capture PWM: %d\n", ret); > + return ret; > + } > + > + if (result.period) > + rpm = DIV_ROUND_CLOSEST_ULL(60ULL * NSEC_PER_SEC, > + result.period); > + > + return sprintf(buf, "%u\n", rpm); > +} > > static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0); > +static SENSOR_DEVICE_ATTR(fan1_input, 0444, show_rpm, NULL, 0); > > static struct attribute *pwm_fan_attrs[] = { > &sensor_dev_attr_pwm1.dev_attr.attr, > + &sensor_dev_attr_fan1_input.dev_attr.attr, This doesn't make sense. The same pwm can not both control the fan speed and report it. Guenter > NULL, > }; > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Mar 21, 2018 at 10:10:36AM +0530, Rajkumar Rampelli wrote: > Add support for pwm HW driver which has only capture functionality. > This helps to implement the PWM based Tachometer driver which reads > the PWM output signals from electronic fans. > > PWM Tachometer captures the period and duty cycle of the PWM signal > > Add conditional checks for callabacks enable(), disable(), config() > to check if they are supported by the client driver or not. Skip these > callbacks if they are not supported. > > Signed-off-by: Rajkumar Rampelli <rrajk@nvidia.com> > --- > > V2: Added if conditional checks for pwm callbacks since drivers may > implements only pwm capture functionality. > > drivers/pwm/core.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..f70fe68 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -246,6 +246,10 @@ static bool pwm_ops_check(const struct pwm_ops *ops) > if (ops->apply) > return true; > > + /* driver supports capture operation */ > + if (ops->capture) > + return true; > + > return false; > } > > @@ -495,7 +499,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) > * ->apply(). > */ > if (pwm->state.enabled) { > - pwm->chip->ops->disable(pwm->chip, pwm); > + if (pwm->chip->ops->disable) > + pwm->chip->ops->disable(pwm->chip, pwm); This is not a good idea. It means that you'll be able to successfully configure a capture-only PWM channel for output. I think all of the output configuration functions should return an error (-ENOSYS?) for capture-only devices, much like we return -ENOSYS for pwm_capture() if the driver doesn't implement capture support. Thierry
The following patches adds support for PWM based Tegra Tachometer driver which implements PWM capture interface to analyze the PWM signal of a electronic fan and reports it in periods and duty cycles. Added fan device attribute fan1_input in pwm-fan driver to monitor the speed of fan in rotations per minute using PWM interface. RPM of Fan will be exposed to user interface through HWMON sysfs interface avialable at location: /sys/class/hwmon/hwmon0/fan1_input Steps to validate Tachometer on Tegra186 SoC: A. push modules pwm-tegra.ko, pwm-tegra-tachometer.ko and pwm-fan.ko to linux device using scp command. scp build/tegra186/drivers/pwm/pwm-tegra.ko ubuntu@10.19.65.176:/tmp/ scp build/tegra186/drivers/pwm/pwm-tegra-tachometer.ko ubuntu@10.19.65.176:/tmp/ scp build/tegra186/drivers/hwmon/pwm-fan.ko ubuntu@10.19.65.176:/tmp/ B. On Linux device console, insert these modules using insmod command. insmod /tmp/pwm-tegra.ko insmod /tmp/pwm-tegra-tachometer.ko insmod /tmp/pwm-fan.ko C. Read RPM value at below sysfs node cat /sys/calss/hwmon/hwmon0/fan1_input D. Change the FAN speed using PWM sysfs interface. Follow below steps for the same: a. cd /sys/class/pwm/pwmchip0 b. ls -la (make sure pwm controller is c340000.pwm) Output should be: device -> ../../../c340000.pwm c. echo 0 > export d. cd pwmchip0:0 e. echo 8000 > period f. echo 1 > enable g. echo 8000 > duty_cycle # change duty_cycles from 0 to 8000 for FAN speed variation h. cat /sys/calss/hwmon/hwmon0/fan1_input i. echo 4000 > duty_cycle h. cat /sys/calss/hwmon/hwmon0/fan1_input i. echo 2000 > duty_cycle h. cat /sys/calss/hwmon/hwmon0/fan1_input i. echo 0 > duty_cycle h. cat /sys/calss/hwmon/hwmon0/fan1_input Rajkumar Rampelli (9): pwm: core: Add support for PWM HW driver with pwm capture only arm64: tegra: Add PWM controller on Tegra186 soc dt-bindings: Tegra186 tachometer device tree bindings arm64: tegra: Add Tachometer Controller on Tegra186 pwm: tegra: Add PWM based Tachometer driver arm64: tegra: Add pwm based fan support on Tegra186 hwmon: pwm-fan: add sysfs node to read rpm of fan arm64: defconfig: enable Nvidia Tegra Tachometer as a module arm64: defconfig: enable pwm-fan as a loadable module .../bindings/pwm/pwm-tegra-tachometer.txt | 31 +++ arch/arm64/boot/dts/nvidia/tegra186-p2771-0000.dts | 5 + arch/arm64/boot/dts/nvidia/tegra186.dtsi | 28 ++ arch/arm64/configs/defconfig | 2 + drivers/hwmon/pwm-fan.c | 23 ++ drivers/pwm/Kconfig | 10 + drivers/pwm/Makefile | 1 + drivers/pwm/core.c | 21 +- drivers/pwm/pwm-tegra-tachometer.c | 303 +++++++++++++++++++++ 9 files changed, 418 insertions(+), 6 deletions(-) create mode 100644 Documentation/devicetree/bindings/pwm/pwm-tegra-tachometer.txt create mode 100644 drivers/pwm/pwm-tegra-tachometer.c