* [PATCH v5] iio: hrtimer: Allow sub Hz granularity
@ 2021-01-12 4:09 Gwendal Grignou
2021-01-12 14:23 ` Andy Shevchenko
0 siblings, 1 reply; 3+ messages in thread
From: Gwendal Grignou @ 2021-01-12 4:09 UTC (permalink / raw)
To: jic23, lars, andy.shevchenko; +Cc: linux-iio, 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>
---
Changes since v4:
- Use do_div() properly.
Changes since v3:
- Fix rebasing issue.
Changes since v2:
- Add do_div to allow divide by a u64 on 32bit machines.
Changes since v1:
- Added documentation.
Documentation/iio/iio_configfs.rst | 1 +
drivers/iio/trigger/iio-trig-hrtimer.c | 26 ++++++++++++++++----------
2 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/Documentation/iio/iio_configfs.rst b/Documentation/iio/iio_configfs.rst
index ecbfdb3afef7e..807589ef2bea0 100644
--- a/Documentation/iio/iio_configfs.rst
+++ b/Documentation/iio/iio_configfs.rst
@@ -99,3 +99,4 @@ Each trigger can have one or more attributes specific to the trigger type.
"hrtimer" trigger type doesn't have any configurable attribute from /config dir.
It does introduce the sampling_frequency attribute to trigger directory.
+That attribute sets the polling frequency in Hz, with mHz precision.
diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
index 58c1c30d5612b..1effab04e00a8 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 +50,22 @@ 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;
+ do_div(info->period, val);
return len;
}
@@ -135,8 +141,8 @@ static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
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)
--
2.30.0.284.gd98b1dd5eaa7-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v5] iio: hrtimer: Allow sub Hz granularity
2021-01-12 4:09 [PATCH v5] iio: hrtimer: Allow sub Hz granularity Gwendal Grignou
@ 2021-01-12 14:23 ` Andy Shevchenko
2021-01-13 0:15 ` Gwendal Grignou
0 siblings, 1 reply; 3+ messages in thread
From: Andy Shevchenko @ 2021-01-12 14:23 UTC (permalink / raw)
To: Gwendal Grignou; +Cc: Jonathan Cameron, Lars-Peter Clausen, linux-iio
On Tue, Jan 12, 2021 at 6:09 AM 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 && \
This && seems strange...
> cd /sys/bus/iio/devices/triggerX ;
...because if the above fails, the below becomes a total train wreck.
> for i in 1 .1 .01 .001 ; do
> echo $i > sampling_frequency
> cat sampling_frequency
> done
Something like this perhaps (note {} and also I dropped unneeded ; and
whitespace)
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
}
...
> + if (!val || val > NSEC_PER_SEC * 1000)
> return -EINVAL;
> + info->period = NSEC_PER_SEC * 1000;
I didn't get these * 1000 parts, why not define and use PSEC_PER_SEC?
I'll send a patch soon. You may include it in your series as prerequisite.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v5] iio: hrtimer: Allow sub Hz granularity
2021-01-12 14:23 ` Andy Shevchenko
@ 2021-01-13 0:15 ` Gwendal Grignou
0 siblings, 0 replies; 3+ messages in thread
From: Gwendal Grignou @ 2021-01-13 0:15 UTC (permalink / raw)
To: Andy Shevchenko; +Cc: Jonathan Cameron, Lars-Peter Clausen, linux-iio
On Tue, Jan 12, 2021 at 6:22 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Tue, Jan 12, 2021 at 6:09 AM 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 && \
>
> This && seems strange...
>
> > cd /sys/bus/iio/devices/triggerX ;
This is just for testing. X in triggerX should be replaced with the
newly created trigger.
>
> ...because if the above fails, the below becomes a total train wreck.
>
> > for i in 1 .1 .01 .001 ; do
> > echo $i > sampling_frequency
> > cat sampling_frequency
> > done
>
> Something like this perhaps (note {} and also I dropped unneeded ; and
> whitespace)
> 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
> }
>
> ...
>
> > + if (!val || val > NSEC_PER_SEC * 1000)
> > return -EINVAL;
>
> > + info->period = NSEC_PER_SEC * 1000;
>
> I didn't get these * 1000 parts, why not define and use PSEC_PER_SEC?
Indeed only Nano and Femto SEC_PER_SEC are defined.
>
> I'll send a patch soon. You may include it in your series as prerequisite.
Thanks,
Gwendal.
>
> --
> With Best Regards,
> Andy Shevchenko
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-01-12 4:09 [PATCH v5] iio: hrtimer: Allow sub Hz granularity Gwendal Grignou
2021-01-12 14:23 ` Andy Shevchenko
2021-01-13 0:15 ` Gwendal Grignou
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