drivers/iio/adc/envelope-detector.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Driver for an envelope detector using a DAC and a comparator
  *
  * Copyright (C) 2016 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
  */

 /*
  * The DAC is used to find the peak level of an alternating voltage input
  * signal by a binary search using the output of a comparator wired to
  * an interrupt pin. Like so:
  *                           _
  *                          | \
  *     input +------>-------|+ \
  *                          |   \
  *            .-------.     |    }---.
  *            |       |     |   /    |
  *            |    dac|-->--|- /     |
  *            |       |     |_/      |
  *            |       |              |
  *            |       |              |
  *            |    irq|------<-------'
  *            |       |
  *            '-------'
  */

 #include <linux/completion.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/mutex.h>
 #include <linux/iio/consumer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>

 struct envelope {
 	spinlock_t comp_lock; /* protects comp */
 	int comp;

 	struct mutex read_lock; /* protects everything else */

 	int comp_irq;
 	u32 comp_irq_trigger;
 	u32 comp_irq_trigger_inv;

 	struct iio_channel *dac;
 	struct delayed_work comp_timeout;

 	unsigned int comp_interval;
 	bool invert;
 	u32 dac_max;

 	int high;
 	int level;
 	int low;

 	struct completion done;
 };

 /*
  * The envelope_detector_comp_latch function works together with the compare
  * interrupt service routine below (envelope_detector_comp_isr) as a latch
  * (one-bit memory) for if the interrupt has triggered since last calling
  * this function.
  * The ..._comp_isr function disables the interrupt so that the cpu does not
  * need to service a possible interrupt flood from the comparator when no-one
  * cares anyway, and this ..._comp_latch function reenables them again if
  * needed.
  */
 static int envelope_detector_comp_latch(struct envelope *env)
 {
 	int comp;

 	spin_lock_irq(&env->comp_lock);
 	comp = env->comp;
 	env->comp = 0;
 	spin_unlock_irq(&env->comp_lock);

 	if (!comp)
 		return 0;

 	/*
 	 * The irq was disabled, and is reenabled just now.
 	 * But there might have been a pending irq that
 	 * happened while the irq was disabled that fires
 	 * just as the irq is reenabled. That is not what
 	 * is desired.
 	 */
 	enable_irq(env->comp_irq);

 	/* So, synchronize this possibly pending irq... */
 	synchronize_irq(env->comp_irq);

 	/* ...and redo the whole dance. */
 	spin_lock_irq(&env->comp_lock);
 	comp = env->comp;
 	env->comp = 0;
 	spin_unlock_irq(&env->comp_lock);

 	if (comp)
 		enable_irq(env->comp_irq);

 	return 1;
 }

 static irqreturn_t envelope_detector_comp_isr(int irq, void *ctx)
 {
 	struct envelope *env = ctx;

 	spin_lock(&env->comp_lock);
 	env->comp = 1;
 	disable_irq_nosync(env->comp_irq);
 	spin_unlock(&env->comp_lock);

 	return IRQ_HANDLED;
 }

 static void envelope_detector_setup_compare(struct envelope *env)
 {
 	int ret;

 	/*
 	 * Do a binary search for the peak input level, and stop
 	 * when that level is "trapped" between two adjacent DAC
 	 * values.
 	 * When invert is active, use the midpoint floor so that
 	 * env->level ends up as env->low when the termination
 	 * criteria below is fulfilled, and use the midpoint
 	 * ceiling when invert is not active so that env->level
 	 * ends up as env->high in that case.
 	 */
 	env->level = (env->high + env->low + !env->invert) / 2;

 	if (env->high == env->low + 1) {
 		complete(&env->done);
 		return;
 	}

 	/* Set a "safe" DAC level (if there is such a thing)... */
 	ret = iio_write_channel_raw(env->dac, env->invert ? 0 : env->dac_max);
 	if (ret < 0)
 		goto err;

 	/* ...clear the comparison result... */
 	envelope_detector_comp_latch(env);

 	/* ...set the real DAC level... */
 	ret = iio_write_channel_raw(env->dac, env->level);
 	if (ret < 0)
 		goto err;

 	/* ...and wait for a bit to see if the latch catches anything. */
 	schedule_delayed_work(&env->comp_timeout,
 			      msecs_to_jiffies(env->comp_interval));
 	return;

 err:
 	env->level = ret;
 	complete(&env->done);
 }

 static void envelope_detector_timeout(struct work_struct *work)
 {
 	struct envelope *env = container_of(work, struct envelope,
 					    comp_timeout.work);

 	/* Adjust low/high depending on the latch content... */
 	if (!envelope_detector_comp_latch(env) ^ !env->invert)
 		env->low = env->level;
 	else
 		env->high = env->level;

 	/* ...and continue the search. */
 	envelope_detector_setup_compare(env);
 }

 static int envelope_detector_read_raw(struct iio_dev *indio_dev,
 				      struct iio_chan_spec const *chan,
 				      int *val, int *val2, long mask)
 {
 	struct envelope *env = iio_priv(indio_dev);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		/*
 		 * When invert is active, start with high=max+1 and low=0
 		 * since we will end up with the low value when the
 		 * termination criteria is fulfilled (rounding down). And
 		 * start with high=max and low=-1 when invert is not active
 		 * since we will end up with the high value in that case.
 		 * This ensures that the returned value in both cases are
 		 * in the same range as the DAC and is a value that has not
 		 * triggered the comparator.
 		 */
 		mutex_lock(&env->read_lock);
 		env->high = env->dac_max + env->invert;
 		env->low = -1 + env->invert;
 		envelope_detector_setup_compare(env);
 		wait_for_completion(&env->done);
 		if (env->level < 0) {
 			ret = env->level;
 			goto err_unlock;
 		}
 		*val = env->invert ? env->dac_max - env->level : env->level;
 		mutex_unlock(&env->read_lock);

 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:
 		return iio_read_channel_scale(env->dac, val, val2);
 	}

 	return -EINVAL;

 err_unlock:
 	mutex_unlock(&env->read_lock);
 	return ret;
 }

 static ssize_t envelope_show_invert(struct iio_dev *indio_dev,
 				    uintptr_t private,
 				    struct iio_chan_spec const *ch, char *buf)
 {
 	struct envelope *env = iio_priv(indio_dev);

 	return sprintf(buf, "%u\n", env->invert);
 }

 static ssize_t envelope_store_invert(struct iio_dev *indio_dev,
 				     uintptr_t private,
 				     struct iio_chan_spec const *ch,
 				     const char *buf, size_t len)
 {
 	struct envelope *env = iio_priv(indio_dev);
 	unsigned long invert;
 	int ret;
 	u32 trigger;

 	ret = kstrtoul(buf, 0, &invert);
 	if (ret < 0)
 		return ret;
 	if (invert > 1)
 		return -EINVAL;

 	trigger = invert ? env->comp_irq_trigger_inv : env->comp_irq_trigger;

 	mutex_lock(&env->read_lock);
 	if (invert != env->invert)
 		ret = irq_set_irq_type(env->comp_irq, trigger);
 	if (!ret) {
 		env->invert = invert;
 		ret = len;
 	}
 	mutex_unlock(&env->read_lock);

 	return ret;
 }

 static ssize_t envelope_show_comp_interval(struct iio_dev *indio_dev,
 					   uintptr_t private,
 					   struct iio_chan_spec const *ch,
 					   char *buf)
 {
 	struct envelope *env = iio_priv(indio_dev);

 	return sprintf(buf, "%u\n", env->comp_interval);
 }

 static ssize_t envelope_store_comp_interval(struct iio_dev *indio_dev,
 					    uintptr_t private,
 					    struct iio_chan_spec const *ch,
 					    const char *buf, size_t len)
 {
 	struct envelope *env = iio_priv(indio_dev);
 	unsigned long interval;
 	int ret;

 	ret = kstrtoul(buf, 0, &interval);
 	if (ret < 0)
 		return ret;
 	if (interval > 1000)
 		return -EINVAL;

 	mutex_lock(&env->read_lock);
 	env->comp_interval = interval;
 	mutex_unlock(&env->read_lock);

 	return len;
 }

 static const struct iio_chan_spec_ext_info envelope_detector_ext_info[] = {
 	{ .name = "invert",
 	  .read = envelope_show_invert,
 	  .write = envelope_store_invert, },
 	{ .name = "compare_interval",
 	  .read = envelope_show_comp_interval,
 	  .write = envelope_store_comp_interval, },
 	{ /* sentinel */ }
 };

 static const struct iio_chan_spec envelope_detector_iio_channel = {
 	.type = IIO_ALTVOLTAGE,
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
 			    | BIT(IIO_CHAN_INFO_SCALE),
 	.ext_info = envelope_detector_ext_info,
 	.indexed = 1,
 };

 static const struct iio_info envelope_detector_info = {
 	.read_raw = &envelope_detector_read_raw,
 };

 static int envelope_detector_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct iio_dev *indio_dev;
 	struct envelope *env;
 	enum iio_chan_type type;
 	int ret;

 	indio_dev = devm_iio_device_alloc(dev, sizeof(*env));
 	if (!indio_dev)
 		return -ENOMEM;

 	platform_set_drvdata(pdev, indio_dev);
 	env = iio_priv(indio_dev);
 	env->comp_interval = 50; /* some sensible default? */

 	spin_lock_init(&env->comp_lock);
 	mutex_init(&env->read_lock);
 	init_completion(&env->done);
 	INIT_DELAYED_WORK(&env->comp_timeout, envelope_detector_timeout);

 	indio_dev->name = dev_name(dev);
 	indio_dev->info = &envelope_detector_info;
 	indio_dev->channels = &envelope_detector_iio_channel;
 	indio_dev->num_channels = 1;

 	env->dac = devm_iio_channel_get(dev, "dac");
 	if (IS_ERR(env->dac))
 		return dev_err_probe(dev, PTR_ERR(env->dac),
 				     "failed to get dac input channel\n");

 	env->comp_irq = platform_get_irq_byname(pdev, "comp");
 	if (env->comp_irq < 0)
 		return env->comp_irq;

 	ret = devm_request_irq(dev, env->comp_irq, envelope_detector_comp_isr,
 			       0, "envelope-detector", env);
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to request interrupt\n");

 	env->comp_irq_trigger = irq_get_trigger_type(env->comp_irq);
 	if (env->comp_irq_trigger & IRQF_TRIGGER_RISING)
 		env->comp_irq_trigger_inv |= IRQF_TRIGGER_FALLING;
 	if (env->comp_irq_trigger & IRQF_TRIGGER_FALLING)
 		env->comp_irq_trigger_inv |= IRQF_TRIGGER_RISING;
 	if (env->comp_irq_trigger & IRQF_TRIGGER_HIGH)
 		env->comp_irq_trigger_inv |= IRQF_TRIGGER_LOW;
 	if (env->comp_irq_trigger & IRQF_TRIGGER_LOW)
 		env->comp_irq_trigger_inv |= IRQF_TRIGGER_HIGH;

 	ret = iio_get_channel_type(env->dac, &type);
 	if (ret < 0)
 		return ret;

 	if (type != IIO_VOLTAGE) {
 		dev_err(dev, "dac is of the wrong type\n");
 		return -EINVAL;
 	}

 	ret = iio_read_max_channel_raw(env->dac, &env->dac_max);
 	if (ret < 0) {
 		dev_err(dev, "dac does not indicate its raw maximum value\n");
 		return ret;
 	}

 	return devm_iio_device_register(dev, indio_dev);
 }

 static const struct of_device_id envelope_detector_match[] = {
 	{ .compatible = "axentia,tse850-envelope-detector", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, envelope_detector_match);

 static struct platform_driver envelope_detector_driver = {
 	.probe = envelope_detector_probe,
 	.driver = {
 		.name = "iio-envelope-detector",
 		.of_match_table = envelope_detector_match,
 	},
 };
 module_platform_driver(envelope_detector_driver);

 MODULE_DESCRIPTION("Envelope detector using a DAC and a comparator");
 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Driver for an envelope detector using a DAC and a comparator
	*
	* Copyright (C) 2016 Axentia Technologies AB
	*
	* Author: Peter Rosin <peda@axentia.se>
	*/

	/*
	* The DAC is used to find the peak level of an alternating voltage input
	* signal by a binary search using the output of a comparator wired to
	* an interrupt pin. Like so:
	* _
	* \| \
	* input +------>-------\|+ \
	* \| \
	* .-------. \| }---.
	* \| \| \| / \|
	* \| dac\|-->--\|- / \|
	* \| \| \|_/ \|
	* \| \| \|
	* \| \| \|
	* \| irq\|------<-------'
	* \| \|
	* '-------'
	*/

	#include <linux/completion.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/mutex.h>
	#include <linux/iio/consumer.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/platform_device.h>
	#include <linux/spinlock.h>
	#include <linux/workqueue.h>

	struct envelope {
	spinlock_t comp_lock; /* protects comp */
	int comp;

	struct mutex read_lock; /* protects everything else */

	int comp_irq;
	u32 comp_irq_trigger;
	u32 comp_irq_trigger_inv;

	struct iio_channel *dac;
	struct delayed_work comp_timeout;

	unsigned int comp_interval;
	bool invert;
	u32 dac_max;

	int high;
	int level;
	int low;

	struct completion done;
	};

	/*
	* The envelope_detector_comp_latch function works together with the compare
	* interrupt service routine below (envelope_detector_comp_isr) as a latch
	* (one-bit memory) for if the interrupt has triggered since last calling
	* this function.
	* The ..._comp_isr function disables the interrupt so that the cpu does not
	* need to service a possible interrupt flood from the comparator when no-one
	* cares anyway, and this ..._comp_latch function reenables them again if
	* needed.
	*/
	static int envelope_detector_comp_latch(struct envelope *env)
	{
	int comp;

	spin_lock_irq(&env->comp_lock);
	comp = env->comp;
	env->comp = 0;
	spin_unlock_irq(&env->comp_lock);

	if (!comp)
	return 0;

	/*
	* The irq was disabled, and is reenabled just now.
	* But there might have been a pending irq that
	* happened while the irq was disabled that fires
	* just as the irq is reenabled. That is not what
	* is desired.
	*/
	enable_irq(env->comp_irq);

	/* So, synchronize this possibly pending irq... */
	synchronize_irq(env->comp_irq);

	/* ...and redo the whole dance. */
	spin_lock_irq(&env->comp_lock);
	comp = env->comp;
	env->comp = 0;
	spin_unlock_irq(&env->comp_lock);

	if (comp)
	enable_irq(env->comp_irq);

	return 1;
	}

	static irqreturn_t envelope_detector_comp_isr(int irq, void *ctx)
	{
	struct envelope *env = ctx;

	spin_lock(&env->comp_lock);
	env->comp = 1;
	disable_irq_nosync(env->comp_irq);
	spin_unlock(&env->comp_lock);

	return IRQ_HANDLED;
	}

	static void envelope_detector_setup_compare(struct envelope *env)
	{
	int ret;

	/*
	* Do a binary search for the peak input level, and stop
	* when that level is "trapped" between two adjacent DAC
	* values.
	* When invert is active, use the midpoint floor so that
	* env->level ends up as env->low when the termination
	* criteria below is fulfilled, and use the midpoint
	* ceiling when invert is not active so that env->level
	* ends up as env->high in that case.
	*/
	env->level = (env->high + env->low + !env->invert) / 2;

	if (env->high == env->low + 1) {
	complete(&env->done);
	return;
	}

	/* Set a "safe" DAC level (if there is such a thing)... */
	ret = iio_write_channel_raw(env->dac, env->invert ? 0 : env->dac_max);
	if (ret < 0)
	goto err;

	/* ...clear the comparison result... */
	envelope_detector_comp_latch(env);

	/* ...set the real DAC level... */
	ret = iio_write_channel_raw(env->dac, env->level);
	if (ret < 0)
	goto err;

	/* ...and wait for a bit to see if the latch catches anything. */
	schedule_delayed_work(&env->comp_timeout,
	msecs_to_jiffies(env->comp_interval));
	return;

	err:
	env->level = ret;
	complete(&env->done);
	}

	static void envelope_detector_timeout(struct work_struct *work)
	{
	struct envelope *env = container_of(work, struct envelope,
	comp_timeout.work);

	/* Adjust low/high depending on the latch content... */
	if (!envelope_detector_comp_latch(env) ^ !env->invert)
	env->low = env->level;
	else
	env->high = env->level;

	/* ...and continue the search. */
	envelope_detector_setup_compare(env);
	}

	static int envelope_detector_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct envelope *env = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	/*
	* When invert is active, start with high=max+1 and low=0
	* since we will end up with the low value when the
	* termination criteria is fulfilled (rounding down). And
	* start with high=max and low=-1 when invert is not active
	* since we will end up with the high value in that case.
	* This ensures that the returned value in both cases are
	* in the same range as the DAC and is a value that has not
	* triggered the comparator.
	*/
	mutex_lock(&env->read_lock);
	env->high = env->dac_max + env->invert;
	env->low = -1 + env->invert;
	envelope_detector_setup_compare(env);
	wait_for_completion(&env->done);
	if (env->level < 0) {
	ret = env->level;
	goto err_unlock;
	}
	*val = env->invert ? env->dac_max - env->level : env->level;
	mutex_unlock(&env->read_lock);

	return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
	return iio_read_channel_scale(env->dac, val, val2);
	}

	return -EINVAL;

	err_unlock:
	mutex_unlock(&env->read_lock);
	return ret;
	}

	static ssize_t envelope_show_invert(struct iio_dev *indio_dev,
	uintptr_t private,
	struct iio_chan_spec const ch, char buf)
	{
	struct envelope *env = iio_priv(indio_dev);

	return sprintf(buf, "%u\n", env->invert);
	}

	static ssize_t envelope_store_invert(struct iio_dev *indio_dev,
	uintptr_t private,
	struct iio_chan_spec const *ch,
	const char *buf, size_t len)
	{
	struct envelope *env = iio_priv(indio_dev);
	unsigned long invert;
	int ret;
	u32 trigger;

	ret = kstrtoul(buf, 0, &invert);
	if (ret < 0)
	return ret;
	if (invert > 1)
	return -EINVAL;

	trigger = invert ? env->comp_irq_trigger_inv : env->comp_irq_trigger;

	mutex_lock(&env->read_lock);
	if (invert != env->invert)
	ret = irq_set_irq_type(env->comp_irq, trigger);
	if (!ret) {
	env->invert = invert;
	ret = len;
	}
	mutex_unlock(&env->read_lock);

	return ret;
	}

	static ssize_t envelope_show_comp_interval(struct iio_dev *indio_dev,
	uintptr_t private,
	struct iio_chan_spec const *ch,
	char *buf)
	{
	struct envelope *env = iio_priv(indio_dev);

	return sprintf(buf, "%u\n", env->comp_interval);
	}

	static ssize_t envelope_store_comp_interval(struct iio_dev *indio_dev,
	uintptr_t private,
	struct iio_chan_spec const *ch,
	const char *buf, size_t len)
	{
	struct envelope *env = iio_priv(indio_dev);
	unsigned long interval;
	int ret;

	ret = kstrtoul(buf, 0, &interval);
	if (ret < 0)
	return ret;
	if (interval > 1000)
	return -EINVAL;

	mutex_lock(&env->read_lock);
	env->comp_interval = interval;
	mutex_unlock(&env->read_lock);

	return len;
	}

	static const struct iio_chan_spec_ext_info envelope_detector_ext_info[] = {
	{ .name = "invert",
	.read = envelope_show_invert,
	.write = envelope_store_invert, },
	{ .name = "compare_interval",
	.read = envelope_show_comp_interval,
	.write = envelope_store_comp_interval, },
	{ /* sentinel */ }
	};

	static const struct iio_chan_spec envelope_detector_iio_channel = {
	.type = IIO_ALTVOLTAGE,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
	\| BIT(IIO_CHAN_INFO_SCALE),
	.ext_info = envelope_detector_ext_info,
	.indexed = 1,
	};

	static const struct iio_info envelope_detector_info = {
	.read_raw = &envelope_detector_read_raw,
	};

	static int envelope_detector_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct iio_dev *indio_dev;
	struct envelope *env;
	enum iio_chan_type type;
	int ret;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*env));
	if (!indio_dev)
	return -ENOMEM;

	platform_set_drvdata(pdev, indio_dev);
	env = iio_priv(indio_dev);
	env->comp_interval = 50; /* some sensible default? */

	spin_lock_init(&env->comp_lock);
	mutex_init(&env->read_lock);
	init_completion(&env->done);
	INIT_DELAYED_WORK(&env->comp_timeout, envelope_detector_timeout);

	indio_dev->name = dev_name(dev);
	indio_dev->info = &envelope_detector_info;
	indio_dev->channels = &envelope_detector_iio_channel;
	indio_dev->num_channels = 1;

	env->dac = devm_iio_channel_get(dev, "dac");
	if (IS_ERR(env->dac))
	return dev_err_probe(dev, PTR_ERR(env->dac),
	"failed to get dac input channel\n");

	env->comp_irq = platform_get_irq_byname(pdev, "comp");
	if (env->comp_irq < 0)
	return env->comp_irq;

	ret = devm_request_irq(dev, env->comp_irq, envelope_detector_comp_isr,
	0, "envelope-detector", env);
	if (ret)
	return dev_err_probe(dev, ret, "failed to request interrupt\n");

	env->comp_irq_trigger = irq_get_trigger_type(env->comp_irq);
	if (env->comp_irq_trigger & IRQF_TRIGGER_RISING)
	env->comp_irq_trigger_inv \|= IRQF_TRIGGER_FALLING;
	if (env->comp_irq_trigger & IRQF_TRIGGER_FALLING)
	env->comp_irq_trigger_inv \|= IRQF_TRIGGER_RISING;
	if (env->comp_irq_trigger & IRQF_TRIGGER_HIGH)
	env->comp_irq_trigger_inv \|= IRQF_TRIGGER_LOW;
	if (env->comp_irq_trigger & IRQF_TRIGGER_LOW)
	env->comp_irq_trigger_inv \|= IRQF_TRIGGER_HIGH;

	ret = iio_get_channel_type(env->dac, &type);
	if (ret < 0)
	return ret;

	if (type != IIO_VOLTAGE) {
	dev_err(dev, "dac is of the wrong type\n");
	return -EINVAL;
	}

	ret = iio_read_max_channel_raw(env->dac, &env->dac_max);
	if (ret < 0) {
	dev_err(dev, "dac does not indicate its raw maximum value\n");
	return ret;
	}

	return devm_iio_device_register(dev, indio_dev);
	}

	static const struct of_device_id envelope_detector_match[] = {
	{ .compatible = "axentia,tse850-envelope-detector", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, envelope_detector_match);

	static struct platform_driver envelope_detector_driver = {
	.probe = envelope_detector_probe,
	.driver = {
	.name = "iio-envelope-detector",
	.of_match_table = envelope_detector_match,
	},
	};
	module_platform_driver(envelope_detector_driver);

	MODULE_DESCRIPTION("Envelope detector using a DAC and a comparator");
	MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
	MODULE_LICENSE("GPL v2");