* [PATCH v3] iio: hrtimer: Allow sub Hz granularity
@ 2021-01-12 0:46 Gwendal Grignou
0 siblings, 0 replies; only message in thread
From: Gwendal Grignou @ 2021-01-12 0:46 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 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 a5e670726717f..ac2c3be164ac6 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;
+ info->period = 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);
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
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