* [PATCH v8] iio: hrtimer: Allow sub Hz granularity
@ 2021-01-29 23:02 Gwendal Grignou
2021-01-30 20:05 ` Andy Shevchenko
0 siblings, 1 reply; 2+ messages in thread
From: Gwendal Grignou @ 2021-01-29 23:02 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 v7:
- Check for sign properly, only allow positive frequencies.
- Return proper error code when input frequency is negative.
Changes since v6:
- Check for sign, only allow positive frequencies.
Changes since v5:
- Properly support do_div on 32bit architecture: quotient must be u64, dividend
u32.
- Use PSEC_PER_SEC from
https://patchwork.kernel.org/project/linux-iio/patch/20210112153709.1074-1-andriy.shevchenko@linux.intel.com/
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 | 30 +++++++++++++++++---------
2 files changed, 21 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 f59bf8d585866..69c2943583b36 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 +50,26 @@ 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;
+ u64 period;
+ int integer, fract, ret;
- ret = kstrtoul(buf, 10, &val);
+ ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
if (ret)
return ret;
+ if (integer < 0 || fract < 0)
+ return -ERANGE;
+
+ val = fract + 1000 * integer;
- if (!val || val > NSEC_PER_SEC)
+ if (!val || val > UINT_MAX)
return -EINVAL;
- info->sampling_frequency = val;
- info->period = NSEC_PER_SEC / val;
+ info->sampling_frequency[0] = integer;
+ info->sampling_frequency[1] = fract * 1000;
+ period = PSEC_PER_SEC;
+ do_div(period, val);
+ info->period = period;
return len;
}
@@ -135,8 +145,8 @@ 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)
--
2.30.0.365.g02bc693789-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v8] iio: hrtimer: Allow sub Hz granularity
2021-01-29 23:02 [PATCH v8] iio: hrtimer: Allow sub Hz granularity Gwendal Grignou
@ 2021-01-30 20:05 ` Andy Shevchenko
0 siblings, 0 replies; 2+ messages in thread
From: Andy Shevchenko @ 2021-01-30 20:05 UTC (permalink / raw)
To: Gwendal Grignou; +Cc: Jonathan Cameron, Lars-Peter Clausen, linux-iio
On Sat, Jan 30, 2021 at 1:02 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 && \
> cd /sys/bus/iio/devices/triggerX ;
> for i in 1 .1 .01 .001 ; do
> echo $i > sampling_frequency
> cat sampling_frequency
> done
I think it's good enough, though one hint below.
After taking it into account
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> ---
> Changes since v7:
> - Check for sign properly, only allow positive frequencies.
> - Return proper error code when input frequency is negative.
>
> Changes since v6:
> - Check for sign, only allow positive frequencies.
>
> Changes since v5:
> - Properly support do_div on 32bit architecture: quotient must be u64, dividend
> u32.
> - Use PSEC_PER_SEC from
> https://patchwork.kernel.org/project/linux-iio/patch/20210112153709.1074-1-andriy.shevchenko@linux.intel.com/
>
> 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 | 30 +++++++++++++++++---------
> 2 files changed, 21 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 f59bf8d585866..69c2943583b36 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 +50,26 @@ 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;
> + u64 period;
> + int integer, fract, ret;
>
> - ret = kstrtoul(buf, 10, &val);
> + ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
> if (ret)
> return ret;
> + if (integer < 0 || fract < 0)
> + return -ERANGE;
> +
> + val = fract + 1000 * integer;
To avoid dependencies right now, define at the top of this file
#define PSEC_PER_SEC 1000000000000LL
#define NSEC_PER_PSEC 1000L
And use them here and there.
val = fract + PSEC_PER_NSEC * integer;
> - if (!val || val > NSEC_PER_SEC)
> + if (!val || val > UINT_MAX)
> return -EINVAL;
>
> - info->sampling_frequency = val;
> - info->period = NSEC_PER_SEC / val;
> + info->sampling_frequency[0] = integer;
> + info->sampling_frequency[1] = fract * 1000;
Likewise.
> + period = PSEC_PER_SEC;
> + do_div(period, val);
> + info->period = period;
>
> return len;
> }
> @@ -135,8 +145,8 @@ 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)
> --
> 2.30.0.365.g02bc693789-goog
>
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-01-30 20:05 ` Andy Shevchenko
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