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Commit ac5006a2 authored by Daniel Baluta's avatar Daniel Baluta Committed by Jonathan Cameron
Browse files

iio: trigger: Introduce IIO hrtimer based trigger 



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: default avatarMarten Svanfeldt <marten@intuitiveaerial.com>
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarDaniel Baluta <daniel.baluta@intel.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent b662f809

drivers/iio/trigger/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -5,6 +5,16 @@ 


menu "Triggers - standalone"



config IIO_HRTIMER_TRIGGER

	tristate "High resolution timer trigger"

	depends on 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

drivers/iio/trigger/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/iio/trigger/iio-trig-hrtimer.c

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+193 −0
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/**

 * The industrial I/O periodic hrtimer trigger driver

 *

 * Copyright (C) Intuitive Aerial AB

 * Written by Marten Svanfeldt, marten@intuitiveaerial.com

 * Copyright (C) 2012, Analog Device Inc.

 *	Author: Lars-Peter Clausen <lars@metafoo.de>

 * 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;

}



static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {

	.probe		= iio_trig_hrtimer_probe,

	.remove		= iio_trig_hrtimer_remove,

};



static 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 <marten@intuitiveaerial.com>");

MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");

MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");

MODULE_LICENSE("GPL v2");