On Fri, Feb 26, 2021 at 3:47 AM Gwendal Grignou <gwendal@xxxxxxxxxxxx> 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 Thanks! Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> > Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx> > --- > Changes since v8: > - Define PSEC_PER_SEC locally to avoid dependency > - Add units of expressions in comment. > > 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@xxxxxxxxxxxxxxx/ > > 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 | 33 ++++++++++++++++++-------- > 2 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/Documentation/iio/iio_configfs.rst b/Documentation/iio/iio_configfs.rst > index 3a5d76f9e2b97..09845fe525e84 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 410de837d0417..aa8cc7391a60d 100644 > --- a/drivers/iio/trigger/iio-trig-hrtimer.c > +++ b/drivers/iio/trigger/iio-trig-hrtimer.c > @@ -16,13 +16,16 @@ > #include <linux/iio/trigger.h> > #include <linux/iio/sw_trigger.h> > > +/* Defined locally, not in time64.h yet. */ > +#define PSEC_PER_SEC 1000000000000LL > + > /* default sampling frequency - 100Hz */ > #define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100 > > 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 +41,9 @@ 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 +53,26 @@ 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; /* mHz */ > > - 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; /* Hz */ > + info->sampling_frequency[1] = fract * 1000; /* uHz */ > + period = PSEC_PER_SEC; > + do_div(period, val); > + info->period = period; /* nS */ > > return len; > } > @@ -135,8 +148,8 @@ 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) > -- > 2.30.1.766.gb4fecdf3b7-goog > -- With Best Regards, Andy Shevchenko
