[v7,4/5] iio: trigger: Introduce IIO hrtimer based trigger

Commit Message

Daniel Baluta Aug. 10, 2015, 10:42 p.m. UTC

This patch registers a new IIO software trigger interrupt source
based on high resolution timers.

Notice that if configfs is enabled we create sampling_frequency
attribute allowing users to change hrtimer period (1/sampling_frequency).

The IIO hrtimer trigger has a long history, this patch is based on
an older version from Marten and Lars-Peter.

Signed-off-by: Marten Svanfeldt <[e-mail]>
Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Daniel Baluta <[e-mail]>
---
 drivers/iio/trigger/Kconfig            |  10 ++
 drivers/iio/trigger/Makefile           |   2 +
 drivers/iio/trigger/iio-trig-hrtimer.c | 193 +++++++++++++++++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 drivers/iio/trigger/iio-trig-hrtimer.c

Comments

Vladimir Barinov Aug. 17, 2015, 12:45 p.m. UTC | #1

Hello Daniel,

I've verified that your hrtimer trigger works.

I have minor suggestions.

Will not it be useful to have ability to stop/start hrtimer polling
not only during attach/detach trigger.

f.e. writing 0 to sampling_frequency will hrtimer_cancel
and writing any valid frequency will hrtimer_start.

Regards,
Vladimir

On 11.08.2015 01:42, Daniel Baluta wrote:
> This patch registers a new IIO software trigger interrupt source
> based on high resolution timers.
>
> Notice that if configfs is enabled we create sampling_frequency
> attribute allowing users to change hrtimer period (1/sampling_frequency).
>
> The IIO hrtimer trigger has a long history, this patch is based on
> an older version from Marten and Lars-Peter.
>
> Signed-off-by: Marten Svanfeldt <[e-mail]>
> Signed-off-by: Lars-Peter Clausen <[e-mail]>
> Signed-off-by: Daniel Baluta <[e-mail]>
> ---
>   drivers/iio/trigger/Kconfig            |  10 ++
>   drivers/iio/trigger/Makefile           |   2 +
>   drivers/iio/trigger/iio-trig-hrtimer.c | 193 +++++++++++++++++++++++++++++++++
>   3 files changed, 205 insertions(+)
>   create mode 100644 drivers/iio/trigger/iio-trig-hrtimer.c
>
> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
> index 7999612..4505281 100644
> --- a/drivers/iio/trigger/Kconfig
> +++ b/drivers/iio/trigger/Kconfig
> @@ -5,6 +5,16 @@
>   
>   menu "Triggers - standalone"
>   
> +config IIO_HRTIMER_TRIGGER
> +	tristate "High resolution timer trigger"
> +	select IIO_SW_TRIGGER
> +	help
> +	  Provides a frequency based IIO trigger using high resolution
> +	  timers as interrupt source.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called iio-trig-hrtimer.
> +
>   config IIO_INTERRUPT_TRIGGER
>   	tristate "Generic interrupt trigger"
>   	help
> diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
> index 0694dae..fe06eb5 100644
> --- a/drivers/iio/trigger/Makefile
> +++ b/drivers/iio/trigger/Makefile
> @@ -3,5 +3,7 @@
>   #
>   
>   # When adding new entries keep the list in alphabetical order
> +
> +obj-$(CONFIG_IIO_HRTIMER_TRIGGER) += iio-trig-hrtimer.o
>   obj-$(CONFIG_IIO_INTERRUPT_TRIGGER) += iio-trig-interrupt.o
>   obj-$(CONFIG_IIO_SYSFS_TRIGGER) += iio-trig-sysfs.o
> diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
> new file mode 100644
> index 0000000..4631c7a
> --- /dev/null
> +++ b/drivers/iio/trigger/iio-trig-hrtimer.c
> @@ -0,0 +1,193 @@
> +/**
> + * The industrial I/O periodic hrtimer trigger driver
> + *
> + * Copyright (C) Intuitive Aerial AB
> + * Written by Marten Svanfeldt, [e-mail]
> + * Copyright (C) 2012, Analog Device Inc.
> + *	Author: Lars-Peter Clausen <[e-mail]>
> + * Copyright (C) 2015, Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + *
> + */
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/hrtimer.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/sw_trigger.h>
> +
> +/* 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;
> +	ktime_t period;
> +};
> +
> +static struct config_item_type iio_hrtimer_type = {
> +	.ct_owner = THIS_MODULE,
> +};
> +
> +static
> +ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
> +					    struct device_attribute *attr,
> +					    char *buf)
> +{
> +	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);
> +}
> +
> +static
> +ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
> +					     struct device_attribute *attr,
> +					     const char *buf, size_t len)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
> +	unsigned long val;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (!val || val > NSEC_PER_SEC)
> +		return -EINVAL;
> +
> +	info->sampling_frequency = val;
> +	info->period = ktime_set(0, NSEC_PER_SEC / val);
> +
> +	return len;
> +}
> +
> +static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
> +		   iio_hrtimer_show_sampling_frequency,
> +		   iio_hrtimer_store_sampling_frequency);
> +
> +static struct attribute *iio_hrtimer_attrs[] = {
> +	&dev_attr_sampling_frequency.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group iio_hrtimer_attr_group = {
> +	.attrs = iio_hrtimer_attrs,
> +};
> +
> +static const struct attribute_group *iio_hrtimer_attr_groups[] = {
> +	&iio_hrtimer_attr_group,
> +	NULL
> +};
> +
> +static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
> +{
> +	struct iio_hrtimer_info *info;
> +
> +	info = container_of(timer, struct iio_hrtimer_info, timer);
> +
> +	hrtimer_forward_now(timer, info->period);
> +	iio_trigger_poll(info->swt.trigger);
> +
> +	return HRTIMER_RESTART;
> +}
> +
> +static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
> +{
> +	struct iio_hrtimer_info *trig_info;
> +
> +	trig_info = iio_trigger_get_drvdata(trig);
> +
> +	if (state)
> +		hrtimer_start(&trig_info->timer, trig_info->period,
> +			      HRTIMER_MODE_REL);
> +	else
> +		hrtimer_cancel(&trig_info->timer);
> +
> +	return 0;
> +}
> +
> +static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
> +	.owner = THIS_MODULE,
> +	.set_trigger_state = iio_trig_hrtimer_set_state,
> +};
> +
> +static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
> +{
> +	struct iio_hrtimer_info *trig_info;
> +	int ret;
> +
> +	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
> +	if (!trig_info)
> +		return ERR_PTR(-ENOMEM);
> +
> +	trig_info->swt.trigger = iio_trigger_alloc("%s", name);
> +	if (!trig_info->swt.trigger) {
> +		ret = -ENOMEM;
> +		goto err_free_trig_info;
> +	}
> +
> +	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
> +	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
> +	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
> +
> +	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 = ktime_set(0, NSEC_PER_SEC /
> +				      trig_info->sampling_frequency);
> +
> +	ret = iio_trigger_register(trig_info->swt.trigger);
> +	if (ret)
> +		goto err_free_trigger;
> +
> +	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
> +	return &trig_info->swt;
> +err_free_trigger:
> +	iio_trigger_free(trig_info->swt.trigger);
> +err_free_trig_info:
> +	kfree(trig_info);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
> +{
> +	struct iio_hrtimer_info *trig_info;
> +
> +	trig_info = iio_trigger_get_drvdata(swt->trigger);
> +
> +	iio_trigger_unregister(swt->trigger);
> +
> +	/* cancel the timer after unreg to make sure no one rearms it */
> +	hrtimer_cancel(&trig_info->timer);
> +	iio_trigger_free(swt->trigger);
> +	kfree(trig_info);
> +
> +	return 0;
> +}
> +
> +const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
> +	.probe		= iio_trig_hrtimer_probe,
> +	.remove		= iio_trig_hrtimer_remove,
> +};
> +
> +struct iio_sw_trigger_type iio_trig_hrtimer = {
> +	.name = "hrtimer",
> +	.owner = THIS_MODULE,
> +	.ops = &iio_trig_hrtimer_ops,
> +};
> +
> +module_iio_sw_trigger_driver(iio_trig_hrtimer);
> +
> +MODULE_AUTHOR("Marten Svanfeldt <[e-mail]>");
> +MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
> +MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
> +MODULE_LICENSE("GPL v2");

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Daniel Baluta Aug. 17, 2015, 12:49 p.m. UTC | #2

On Mon, Aug 17, 2015 at 3:45 PM, Vladimir Barinov
<[e-mail]> wrote:
> Hello Daniel,
>
> I've verified that your hrtimer trigger works.
>
> I have minor suggestions.
>
> Will not it be useful to have ability to stop/start hrtimer polling
> not only during attach/detach trigger.
>
> f.e. writing 0 to sampling_frequency will hrtimer_cancel
> and writing any valid frequency will hrtimer_start.

Thanks a lot Vladimir for looking at this. I will try to address your comments
this week.

Daniel.
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Lars-Peter Clausen Aug. 31, 2015, 2:57 p.m. UTC | #3

On 08/17/2015 02:45 PM, Vladimir Barinov wrote:
> Hello Daniel,
> 
> I've verified that your hrtimer trigger works.
> 
> I have minor suggestions.
> 
> Will not it be useful to have ability to stop/start hrtimer polling
> not only during attach/detach trigger.
> 
> f.e. writing 0 to sampling_frequency will hrtimer_cancel
> and writing any valid frequency will hrtimer_start.

What's the use case for this?
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Lars-Peter Clausen Aug. 31, 2015, 3:13 p.m. UTC | #4

On 08/11/2015 12:42 AM, Daniel Baluta wrote:
[...]
> +
> +static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
> +{
> +	struct iio_hrtimer_info *trig_info;
> +	int ret;
> +
> +	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
> +	if (!trig_info)
> +		return ERR_PTR(-ENOMEM);
> +
> +	trig_info->swt.trigger = iio_trigger_alloc("%s", name);
> +	if (!trig_info->swt.trigger) {
> +		ret = -ENOMEM;
> +		goto err_free_trig_info;
> +	}
> +
> +	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
> +	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
> +	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
> +
> +	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 = ktime_set(0, NSEC_PER_SEC /
> +				      trig_info->sampling_frequency);
> +
> +	ret = iio_trigger_register(trig_info->swt.trigger);

I think it makes sense to move the register and unregister to the swt core.
This is something you'd always want to do as the last step in the probe and
the first step in the remove function.

> +	if (ret)
> +		goto err_free_trigger;
> +
> +	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
> +	return &trig_info->swt;
> +err_free_trigger:
> +	iio_trigger_free(trig_info->swt.trigger);
> +err_free_trig_info:
> +	kfree(trig_info);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
> +{
> +	struct iio_hrtimer_info *trig_info;
> +
> +	trig_info = iio_trigger_get_drvdata(swt->trigger);
> +
> +	iio_trigger_unregister(swt->trigger);
> +
> +	/* cancel the timer after unreg to make sure no one rearms it */
> +	hrtimer_cancel(&trig_info->timer);
> +	iio_trigger_free(swt->trigger);
> +	kfree(trig_info);
> +
> +	return 0;
> +}
> +
> +const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {

static

> +	.probe		= iio_trig_hrtimer_probe,
> +	.remove		= iio_trig_hrtimer_remove,
> +};
> +
> +struct iio_sw_trigger_type iio_trig_hrtimer = {

static

> +	.name = "hrtimer",
> +	.owner = THIS_MODULE,
> +	.ops = &iio_trig_hrtimer_ops,
> +};
> +
> +module_iio_sw_trigger_driver(iio_trig_hrtimer);
> +
> +MODULE_AUTHOR("Marten Svanfeldt <[e-mail]>");
> +MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
> +MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
> +MODULE_LICENSE("GPL v2");
> 

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Vladimir Barinov Sept. 2, 2015, 12:16 p.m. UTC | #5

Hi Lars,

On 31.08.2015 17:57, Lars-Peter Clausen wrote:
> On 08/17/2015 02:45 PM, Vladimir Barinov wrote:
>> Hello Daniel,
>>
>> I've verified that your hrtimer trigger works.
>>
>> I have minor suggestions.
>>
>> Will not it be useful to have ability to stop/start hrtimer polling
>> not only during attach/detach trigger.
>>
>> f.e. writing 0 to sampling_frequency will hrtimer_cancel
>> and writing any valid frequency will hrtimer_start.
> What's the use case for this?
Setting sampling frequency to 0 Hz.

I do agree that 0Hz is meaningless and the same effect
is achieved by removing trigger from iio device,
but having 0 Hz frequency could probably be more consecutive
for this trigger instead of returning EINVAL.

Regards,
Vladimir

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Patch

diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
index 7999612..4505281 100644
--- a/drivers/iio/trigger/Kconfig
+++ b/drivers/iio/trigger/Kconfig
@@ -5,6 +5,16 @@ 
 
 menu "Triggers - standalone"
 
+config IIO_HRTIMER_TRIGGER
+	tristate "High resolution timer trigger"
+	select IIO_SW_TRIGGER
+	help
+	  Provides a frequency based IIO trigger using high resolution
+	  timers as interrupt source.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called iio-trig-hrtimer.
+
 config IIO_INTERRUPT_TRIGGER
 	tristate "Generic interrupt trigger"
 	help
diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
index 0694dae..fe06eb5 100644
--- a/drivers/iio/trigger/Makefile
+++ b/drivers/iio/trigger/Makefile
@@ -3,5 +3,7 @@ 
 #
 
 # When adding new entries keep the list in alphabetical order
+
+obj-$(CONFIG_IIO_HRTIMER_TRIGGER) += iio-trig-hrtimer.o
 obj-$(CONFIG_IIO_INTERRUPT_TRIGGER) += iio-trig-interrupt.o
 obj-$(CONFIG_IIO_SYSFS_TRIGGER) += iio-trig-sysfs.o
diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
new file mode 100644
index 0000000..4631c7a
--- /dev/null
+++ b/drivers/iio/trigger/iio-trig-hrtimer.c
@@ -0,0 +1,193 @@ 
+/**
+ * The industrial I/O periodic hrtimer trigger driver
+ *
+ * Copyright (C) Intuitive Aerial AB
+ * Written by Marten Svanfeldt, [e-mail]
+ * Copyright (C) 2012, Analog Device Inc.
+ *	Author: Lars-Peter Clausen <[e-mail]>
+ * Copyright (C) 2015, Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/hrtimer.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/sw_trigger.h>
+
+/* 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;
+	ktime_t period;
+};
+
+static struct config_item_type iio_hrtimer_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static
+ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	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);
+}
+
+static
+ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t len)
+{
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	if (!val || val > NSEC_PER_SEC)
+		return -EINVAL;
+
+	info->sampling_frequency = val;
+	info->period = ktime_set(0, NSEC_PER_SEC / val);
+
+	return len;
+}
+
+static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
+		   iio_hrtimer_show_sampling_frequency,
+		   iio_hrtimer_store_sampling_frequency);
+
+static struct attribute *iio_hrtimer_attrs[] = {
+	&dev_attr_sampling_frequency.attr,
+	NULL
+};
+
+static const struct attribute_group iio_hrtimer_attr_group = {
+	.attrs = iio_hrtimer_attrs,
+};
+
+static const struct attribute_group *iio_hrtimer_attr_groups[] = {
+	&iio_hrtimer_attr_group,
+	NULL
+};
+
+static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
+{
+	struct iio_hrtimer_info *info;
+
+	info = container_of(timer, struct iio_hrtimer_info, timer);
+
+	hrtimer_forward_now(timer, info->period);
+	iio_trigger_poll(info->swt.trigger);
+
+	return HRTIMER_RESTART;
+}
+
+static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_hrtimer_info *trig_info;
+
+	trig_info = iio_trigger_get_drvdata(trig);
+
+	if (state)
+		hrtimer_start(&trig_info->timer, trig_info->period,
+			      HRTIMER_MODE_REL);
+	else
+		hrtimer_cancel(&trig_info->timer);
+
+	return 0;
+}
+
+static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = iio_trig_hrtimer_set_state,
+};
+
+static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
+{
+	struct iio_hrtimer_info *trig_info;
+	int ret;
+
+	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
+	if (!trig_info)
+		return ERR_PTR(-ENOMEM);
+
+	trig_info->swt.trigger = iio_trigger_alloc("%s", name);
+	if (!trig_info->swt.trigger) {
+		ret = -ENOMEM;
+		goto err_free_trig_info;
+	}
+
+	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
+	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
+	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
+
+	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 = ktime_set(0, NSEC_PER_SEC /
+				      trig_info->sampling_frequency);
+
+	ret = iio_trigger_register(trig_info->swt.trigger);
+	if (ret)
+		goto err_free_trigger;
+
+	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
+	return &trig_info->swt;
+err_free_trigger:
+	iio_trigger_free(trig_info->swt.trigger);
+err_free_trig_info:
+	kfree(trig_info);
+
+	return ERR_PTR(ret);
+}
+
+static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
+{
+	struct iio_hrtimer_info *trig_info;
+
+	trig_info = iio_trigger_get_drvdata(swt->trigger);
+
+	iio_trigger_unregister(swt->trigger);
+
+	/* cancel the timer after unreg to make sure no one rearms it */
+	hrtimer_cancel(&trig_info->timer);
+	iio_trigger_free(swt->trigger);
+	kfree(trig_info);
+
+	return 0;
+}
+
+const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
+	.probe		= iio_trig_hrtimer_probe,
+	.remove		= iio_trig_hrtimer_remove,
+};
+
+struct iio_sw_trigger_type iio_trig_hrtimer = {
+	.name = "hrtimer",
+	.owner = THIS_MODULE,
+	.ops = &iio_trig_hrtimer_ops,
+};
+
+module_iio_sw_trigger_driver(iio_trig_hrtimer);
+
+MODULE_AUTHOR("Marten Svanfeldt <[e-mail]>");
+MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
+MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
+MODULE_LICENSE("GPL v2");