[PATCH] iio: hrtimer: Allow sub Hz granularity

[PATCH] iio: hrtimer: Allow sub Hz granularity

[Gwendal Grignou]

Allow setting frequency below 1Hz or sub 1Hz precision.
Useful for slow sensors like ALS.

Test frequency is set properly:
modprobe iio-trig-hrtimer && \
mkdir /sys/kernel/config/iio/triggers/hrtimer/t1 && \
cd /sys/bus/iio/devices/triggerX ;
for i in 1 .1 .01 .001 ; do
  echo $i > sampling_frequency
  cat sampling_frequency
done

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 drivers/iio/trigger/iio-trig-hrtimer.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
index a5e670726717f..06acd6dc79a8c 100644
--- a/drivers/iio/trigger/iio-trig-hrtimer.c
+++ b/drivers/iio/trigger/iio-trig-hrtimer.c
@@ -22,7 +22,7 @@
 struct iio_hrtimer_info {
 	struct iio_sw_trigger swt;
 	struct hrtimer timer;
-	unsigned long sampling_frequency;
+	int sampling_frequency[2];
 	ktime_t period;
 };
 
@@ -38,7 +38,9 @@ ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
 	struct iio_trigger *trig = to_iio_trigger(dev);
 	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 
-	return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency);
+	return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO,
+			ARRAY_SIZE(info->sampling_frequency),
+			info->sampling_frequency);
 }
 
 static
@@ -48,18 +50,21 @@ ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
 {
 	struct iio_trigger *trig = to_iio_trigger(dev);
 	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
-	unsigned long val;
-	int ret;
+	unsigned long long val;
+	int integer, fract, ret;
 
-	ret = kstrtoul(buf, 10, &val);
+	ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
 	if (ret)
 		return ret;
 
-	if (!val || val > NSEC_PER_SEC)
+	val = fract + 1000 * integer;
+
+	if (!val || val > NSEC_PER_SEC * 1000)
 		return -EINVAL;
 
-	info->sampling_frequency = val;
-	info->period = NSEC_PER_SEC / val;
+	info->sampling_frequency[0] = integer;
+	info->sampling_frequency[1] = fract * 1000;
+	info->period = NSEC_PER_SEC * 1000 / val;
 
 	return len;
 }
@@ -135,8 +140,8 @@ static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
 	hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	trig_info->timer.function = iio_hrtimer_trig_handler;
 
-	trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
-	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency;
+	trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
+	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0];
 
 	ret = iio_trigger_register(trig_info->swt.trigger);
 	if (ret)
-- 
2.29.2.576.ga3fc446d84-goog

Re: [PATCH] iio: hrtimer: Allow sub Hz granularity

[Jonathan Cameron]

On Fri,  4 Dec 2020 11:48:03 -0800
Gwendal Grignou <gwendal@chromium.org> wrote:

> Allow setting frequency below 1Hz or sub 1Hz precision.
> Useful for slow sensors like ALS.
> 
> Test frequency is set properly:
> modprobe iio-trig-hrtimer && \
> mkdir /sys/kernel/config/iio/triggers/hrtimer/t1 && \
> cd /sys/bus/iio/devices/triggerX ;
> for i in 1 .1 .01 .001 ; do
>   echo $i > sampling_frequency
>   cat sampling_frequency
> done
> 
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Looks good to me. I'd like this one to sit on the list a little longer though
+ it's missed this cycle anyway so we have plenty of time!

Jonathan

> ---
>  drivers/iio/trigger/iio-trig-hrtimer.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
> index a5e670726717f..06acd6dc79a8c 100644
> --- a/drivers/iio/trigger/iio-trig-hrtimer.c
> +++ b/drivers/iio/trigger/iio-trig-hrtimer.c
> @@ -22,7 +22,7 @@
>  struct iio_hrtimer_info {
>  	struct iio_sw_trigger swt;
>  	struct hrtimer timer;
> -	unsigned long sampling_frequency;
> +	int sampling_frequency[2];
>  	ktime_t period;
>  };
>  
> @@ -38,7 +38,9 @@ ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
>  	struct iio_trigger *trig = to_iio_trigger(dev);
>  	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
>  
> -	return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency);
> +	return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO,
> +			ARRAY_SIZE(info->sampling_frequency),
> +			info->sampling_frequency);
>  }
>  
>  static
> @@ -48,18 +50,21 @@ ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
>  {
>  	struct iio_trigger *trig = to_iio_trigger(dev);
>  	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
> -	unsigned long val;
> -	int ret;
> +	unsigned long long val;
> +	int integer, fract, ret;
>  
> -	ret = kstrtoul(buf, 10, &val);
> +	ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
>  	if (ret)
>  		return ret;
>  
> -	if (!val || val > NSEC_PER_SEC)
> +	val = fract + 1000 * integer;
> +
> +	if (!val || val > NSEC_PER_SEC * 1000)
>  		return -EINVAL;
>  
> -	info->sampling_frequency = val;
> -	info->period = NSEC_PER_SEC / val;
> +	info->sampling_frequency[0] = integer;
> +	info->sampling_frequency[1] = fract * 1000;
> +	info->period = NSEC_PER_SEC * 1000 / val;
>  
>  	return len;
>  }
> @@ -135,8 +140,8 @@ static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
>  	hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>  	trig_info->timer.function = iio_hrtimer_trig_handler;
>  
> -	trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
> -	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency;
> +	trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
> +	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0];
>  
>  	ret = iio_trigger_register(trig_info->swt.trigger);
>  	if (ret)

Re: [PATCH] iio: hrtimer: Allow sub Hz granularity

[Andy Shevchenko]

On Sat, Dec 5, 2020 at 8:45 PM Jonathan Cameron <jic23@kernel.org> wrote:
> On Fri,  4 Dec 2020 11:48:03 -0800
> Gwendal Grignou <gwendal@chromium.org> wrote:

> Looks good to me. I'd like this one to sit on the list a little longer though
> + it's missed this cycle anyway so we have plenty of time!

The patch has a big issue, i.e. documentation update... where?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] iio: hrtimer: Allow sub Hz granularity

[Gwendal Grignou]

On Wed, Dec 9, 2020 at 7:22 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Sat, Dec 5, 2020 at 8:45 PM Jonathan Cameron <jic23@kernel.org> wrote:
> > On Fri,  4 Dec 2020 11:48:03 -0800
> > Gwendal Grignou <gwendal@chromium.org> wrote:
>
> > Looks good to me. I'd like this one to sit on the list a little longer though
> > + it's missed this cycle anyway so we have plenty of time!
>
> The patch has a big issue, i.e. documentation update... where?
Added in V2.
>
> --
> With Best Regards,
> Andy Shevchenko

Re: [PATCH] iio: hrtimer: Allow sub Hz granularity

[Jonathan Cameron]

On Wed, 9 Dec 2020 17:22:54 +0200
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Sat, Dec 5, 2020 at 8:45 PM Jonathan Cameron <jic23@kernel.org> wrote:
> > On Fri,  4 Dec 2020 11:48:03 -0800
> > Gwendal Grignou <gwendal@chromium.org> wrote:  
> 
> > Looks good to me. I'd like this one to sit on the list a little longer though
> > + it's missed this cycle anyway so we have plenty of time!  
> 
> The patch has a big issue, i.e. documentation update... where?
Odd corner case. It was never documented tightly enough to rule this out.
So to be honest, I would have expected this to already work, but never
really thought about it before this patch.

Jonathan

>