Messages in this thread | | | Subject | Re: [PATCH V4 3/3] hwmon: pwm-fan: Add RPM support via external interrupt | From | Stefan Wahren <> | Date | Wed, 3 Apr 2019 18:23:04 +0200 |
| |
Am 03.04.2019 um 17:59 schrieb Robin Murphy: > On 03/04/2019 10:55, Stefan Wahren wrote: >> Hi Guenter, >> >> Am 02.04.19 um 22:55 schrieb Guenter Roeck: >>> On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote: >>>> This adds RPM support to the pwm-fan driver in order to use with >>>> fancontrol/pwmconfig. This feature is intended for fans with a >>>> tachometer >>>> output signal, which generate a defined number of pulses per >>>> revolution. >>>> >>>> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> >>>> --- >>>> drivers/hwmon/pwm-fan.c | 111 >>>> ++++++++++++++++++++++++++++++++++++++++++++++-- >>>> 1 file changed, 107 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c >>>> index 167221c..3245a49 100644 >>>> --- a/drivers/hwmon/pwm-fan.c >>>> +++ b/drivers/hwmon/pwm-fan.c >>>> @@ -18,6 +18,7 @@ >>>> #include <linux/hwmon.h> >>>> #include <linux/hwmon-sysfs.h> >>>> +#include <linux/interrupt.h> >>>> #include <linux/module.h> >>>> #include <linux/mutex.h> >>>> #include <linux/of.h> >>>> @@ -26,6 +27,7 @@ >>>> #include <linux/regulator/consumer.h> >>>> #include <linux/sysfs.h> >>>> #include <linux/thermal.h> >>>> +#include <linux/timer.h> >>>> #define MAX_PWM 255 >>>> @@ -33,6 +35,14 @@ struct pwm_fan_ctx { >>>> struct mutex lock; >>>> struct pwm_device *pwm; >>>> struct regulator *reg_en; >>>> + >>>> + int irq; >>>> + atomic_t pulses; >>>> + unsigned int rpm; >>>> + u8 pulses_per_revolution; >>>> + ktime_t sample_start; >>>> + struct timer_list rpm_timer; >>>> + >>>> unsigned int pwm_value; >>>> unsigned int pwm_fan_state; >>>> unsigned int pwm_fan_max_state; >>>> @@ -40,6 +50,32 @@ struct pwm_fan_ctx { >>>> struct thermal_cooling_device *cdev; >>>> }; >>>> +/* This handler assumes self resetting edge triggered interrupt. */ >>>> +static irqreturn_t pulse_handler(int irq, void *dev_id) >>>> +{ >>>> + struct pwm_fan_ctx *ctx = dev_id; >>>> + >>>> + atomic_inc(&ctx->pulses); >>>> + >>>> + return IRQ_HANDLED; >>>> +} >>>> + >>>> +static void sample_timer(struct timer_list *t) >>>> +{ >>>> + struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer); >>>> + int pulses; >>>> + u64 tmp; >>>> + >>>> + pulses = atomic_read(&ctx->pulses); >>>> + atomic_sub(pulses, &ctx->pulses); >>>> + tmp = (u64)pulses * ktime_ms_delta(ktime_get(), >>>> ctx->sample_start) * 60; >>>> + do_div(tmp, ctx->pulses_per_revolution * 1000); >>>> + ctx->rpm = tmp; >>>> + >>>> + ctx->sample_start = ktime_get(); >>>> + mod_timer(&ctx->rpm_timer, jiffies + HZ); >>>> +} >>>> + >>>> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm) >>>> { >>>> unsigned long period; >>>> @@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, >>>> struct device_attribute *attr, >>>> return sprintf(buf, "%u\n", ctx->pwm_value); >>>> } >>>> +static ssize_t rpm_show(struct device *dev, >>>> + struct device_attribute *attr, char *buf) >>>> +{ >>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); >>>> + >>>> + return sprintf(buf, "%u\n", ctx->rpm); >>>> +} >>>> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0); >>>> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0); >>>> static struct attribute *pwm_fan_attrs[] = { >>>> &sensor_dev_attr_pwm1.dev_attr.attr, >>>> + &sensor_dev_attr_fan1_input.dev_attr.attr, >>>> NULL, >>>> }; >>>> -ATTRIBUTE_GROUPS(pwm_fan); >>>> +static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct >>>> attribute *a, >>>> + int n) >>>> +{ >>>> + struct device *dev = container_of(kobj, struct device, kobj); >>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev); >>>> + struct device_attribute *devattr; >>>> + >>>> + /* Hide fan_input in case no interrupt is available */ >>>> + devattr = container_of(a, struct device_attribute, attr); >>>> + if (devattr == &sensor_dev_attr_fan1_input.dev_attr) { >>>> + if (ctx->irq <= 0) >>>> + return 0; >>>> + } >>> Side note: This can be easier written as >>> if (n == 1 && ctx->irq <= 0) >>> return 0; >>> >>> Not that it matters much. >>> >>>> + >>>> + return a->mode; >>>> +} >>>> + >>>> +static const struct attribute_group pwm_fan_group = { >>>> + .attrs = pwm_fan_attrs, >>>> + .is_visible = pwm_fan_attrs_visible, >>>> +}; >>>> + >>>> +static const struct attribute_group *pwm_fan_groups[] = { >>>> + &pwm_fan_group, >>>> + NULL, >>>> +}; >>>> /* thermal cooling device callbacks */ >>>> static int pwm_fan_get_max_state(struct thermal_cooling_device >>>> *cdev, >>>> @@ -261,17 +331,45 @@ static int pwm_fan_probe(struct >>>> platform_device *pdev) >>>> goto err_reg_disable; >>>> } >>>> + timer_setup(&ctx->rpm_timer, sample_timer, 0); >>>> + >>>> + if (of_property_read_u8(pdev->dev.of_node, >>>> "pulses-per-revolution", >>> This does not work: The property is not defined as u8. You have to >>> either >>> use of_property_read_u32() or declare the property as u8. >> pulses_per_revolution is defined as u8 since this version > > The variable might be, but the "pulses-per-revolution" property itself > is not being defined with the appropriate DT type ("/bits/ 8") in the > binding, and thus will be stored as a regular 32-bit cell, for which > reading it as a u8 array may or may not work correctly depending on > endianness. > > TBH, unless there's a real need for a specific binary format in the > FDT, I don't think it's usually worth the bother of using irregular DT > types, especially when the practical impact amounts to possibly saving > up to 3 bytes for a property which usually won't need to be specified > anyway. I'd just do something like: > > u32 ppr = 2; > > of_property_read_u32(np, "pulses-per-revolution", &ppr); > ctx->pulses_per_revolution = ppr;
My intention was to avoid another overflow in case the device tree provides unrealistic values ( my expected range 1 - 10 ). Saving space would be a benefit, but i'm okay with this suggestion.
> >>> >>> [ Sorry, I didn't know until recently that this is necessary ] >>> >>>> + &ctx->pulses_per_revolution)) { >>>> + ctx->pulses_per_revolution = 2; >>>> + } >>>> + >>>> + if (!ctx->pulses_per_revolution) { >>>> + dev_err(&pdev->dev, "pulses-per-revolution can't be >>>> zero.\n"); >>>> + ret = -EINVAL; >>>> + goto err_pwm_disable; >>>> + } >>>> + >>>> + ctx->irq = platform_get_irq(pdev, 0); >>>> + if (ctx->irq == -EPROBE_DEFER) { >>>> + ret = ctx->irq; >>>> + goto err_pwm_disable; >>> It might be better to call platform_get_irq() and to do do this check >>> first, before enabling the regulator (in practice before calling >>> devm_regulator_get_optional). It doesn't make sense to enable the >>> regulator only to disable it because the irq is not yet available. >>> >>>> + } else if (ctx->irq > 0) { >>> As written, this else is unnecessary, and static checkers will complain >>> about it. >>> >>>> + ret = devm_request_irq(&pdev->dev, ctx->irq, >>>> pulse_handler, 0, >>>> + pdev->name, ctx); >>>> + if (ret) { >>>> + dev_err(&pdev->dev, "Can't get interrupt working.\n"); >>>> + goto err_pwm_disable; > > We could still continue without RPM support at this point, couldn't > we? Or is this a deliberate "if that failed, then who knows how messed > up the system is..." kind of thing?
In case someone specified an interrupt, the user expect it to work. This helps to identify broken DT faster.
The gpio-fan also have optional irq support and also bail out if devm_request_irq fails.
Btw i will add the return code into the error message.
Stefan
| |