linux-kernel - Re: [PATCH v2 4/5] iio: trigger: Add periodic polling to SYSFS trigger

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Date:	Tue, 28 Jul 2015 08:34:08 +0200 (CEST)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Vladimir Barinov <vladimir.barinov@...entembedded.com>
cc:	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	cory.tusar@...1solutions.com
Subject: Re: [PATCH v2 4/5] iio: trigger: Add periodic polling to SYSFS
 trigger

On Tue, 28 Jul 2015, Vladimir Barinov wrote:

> Add periodic polling functionality to SYSFS trigger

typos below

> Signed-off-by: Vladimir Barinov <vladimir.barinov@...entembedded.com>
> ---
> Changes in version 2:
> - initially added
> 
>  .../ABI/testing/sysfs-bus-iio-trigger-sysfs        | 11 ++++
>  drivers/iio/trigger/iio-trig-sysfs.c               | 58 ++++++++++++++++++++++
>  2 files changed, 69 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs b/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs
> index 5235e6c..49caff2 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs
> @@ -9,3 +9,14 @@ Description:
>  		automated testing or in situations, where other trigger methods
>  		are not applicable. For example no RTC or spare GPIOs.
>  		X is the IIO index of the trigger.
> +
> +What:		/sys/bus/iio/devices/triggerX/trigger_poll
> +KernelVersion:	4.2.0
> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +		This file is provided by the iio-trig-sysfs stand-alone trigger
> +		driver. Writing this file with positive value (in milliseconds)
> +		will start peroidic event triggereing of the driver, associated

periodic
triggering

> +		with this trigger. Writing this file with 0 will stop perioding
> +		triggering.
> +		X is the IIO index of the trigger.
> diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
> index 3dfab2b..ea79311 100644
> --- a/drivers/iio/trigger/iio-trig-sysfs.c
> +++ b/drivers/iio/trigger/iio-trig-sysfs.c
> @@ -18,6 +18,8 @@
>  struct iio_sysfs_trig {
>  	struct iio_trigger *trig;
>  	struct irq_work work;
> +	struct delayed_work poll_work;
> +	unsigned int poll_interval; /* msec */
>  	int id;
>  	struct list_head l;
>  };
> @@ -110,10 +112,63 @@ static ssize_t iio_sysfs_trigger_poll(struct device *dev,
>  	return count;
>  }
>  
> +static void iio_sysfs_trigger_queue_poll_work(struct iio_sysfs_trig *trig)
> +{
> +	unsigned long delay;
> +
> +	delay = msecs_to_jiffies(trig->poll_interval);
> +	if (delay >= HZ)
> +		delay = round_jiffies_relative(delay);
> +
> +	queue_delayed_work(system_freezable_wq, &trig->poll_work, delay);
> +}
> +
> +static void iio_sysfs_trigger_poll_work(struct work_struct *work)
> +{
> +	struct iio_sysfs_trig *trig = container_of(work, struct iio_sysfs_trig,
> +						   poll_work.work);
> +
> +	irq_work_queue(&trig->work);
> +	iio_sysfs_trigger_queue_poll_work(trig);
> +}
> +
> +static ssize_t iio_sysfs_trigger_get_poll(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct iio_sysfs_trig *sysfs_trig = iio_trigger_get_drvdata(trig);
> +
> +	return sprintf(buf, "%d\n", sysfs_trig->poll_interval);
> +}
> +
> +static ssize_t iio_sysfs_trigger_set_poll(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t count)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct iio_sysfs_trig *sysfs_trig = iio_trigger_get_drvdata(trig);
> +	unsigned int interval;
> +	int err;
> +
> +	err = kstrtouint(buf, 0, &interval);
> +	if (err)
> +		return err;
> +
> +	sysfs_trig->poll_interval = interval;
> +
> +	cancel_delayed_work_sync(&sysfs_trig->poll_work);
> +	if (sysfs_trig->poll_interval > 0)
> +		iio_sysfs_trigger_queue_poll_work(sysfs_trig);
> +
> +	return count;
> +}
> +
>  static DEVICE_ATTR(trigger_now, S_IWUSR, NULL, iio_sysfs_trigger_poll);
> +static DEVICE_ATTR(trigger_poll, S_IRUGO | S_IWUSR, iio_sysfs_trigger_get_poll,
> +						    iio_sysfs_trigger_set_poll);
>  
>  static struct attribute *iio_sysfs_trigger_attrs[] = {
>  	&dev_attr_trigger_now.attr,
> +	&dev_attr_trigger_poll.attr,
>  	NULL,
>  };
>  
> @@ -164,6 +219,7 @@ static int iio_sysfs_trigger_probe(int id)
>  	iio_trigger_set_drvdata(t->trig, t);
>  
>  	init_irq_work(&t->work, iio_sysfs_trigger_work);
> +	INIT_DELAYED_WORK(&t->poll_work, iio_sysfs_trigger_poll_work);
>  
>  	ret = iio_trigger_register(t->trig);
>  	if (ret)
> @@ -198,6 +254,8 @@ static int iio_sysfs_trigger_remove(int id)
>  		return -EINVAL;
>  	}
>  
> +	cancel_delayed_work_sync(&t->poll_work);
> +
>  	iio_trigger_unregister(t->trig);
>  	iio_trigger_free(t->trig);
>  
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
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