[linux.git] / drivers / iio / dac / dpot-dac.c

// SPDX-License-Identifier: GPL-2.0
/*
 * IIO DAC emulation driver using a digital potentiometer
 *
 * Copyright (C) 2016 Axentia Technologies AB
 *
 * Author: Peter Rosin <[email protected]>
 */

/*
 * It is assumed that the dpot is used as a voltage divider between the
 * current dpot wiper setting and the maximum resistance of the dpot. The
 * divided voltage is provided by a vref regulator.
 *
 *                   .------.
 *    .-----------.  |      |
 *    | vref      |--'    .---.
 *    | regulator |--.    |   |
 *    '-----------'  |    | d |
 *                   |    | p |
 *                   |    | o |  wiper
 *                   |    | t |<---------+
 *                   |    |   |
 *                   |    '---'       dac output voltage
 *                   |      |
 *                   '------+------------+
 */

#include <linux/err.h>
#include <linux/iio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

struct dpot_dac {
	struct regulator *vref;
	struct iio_channel *dpot;
	u32 max_ohms;
};

static const struct iio_chan_spec dpot_dac_iio_channel = {
	.type = IIO_VOLTAGE,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
			    | BIT(IIO_CHAN_INFO_SCALE),
	.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
	.output = 1,
	.indexed = 1,
};

static int dpot_dac_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int *val, int *val2, long mask)
{
	struct dpot_dac *dac = iio_priv(indio_dev);
	int ret;
	unsigned long long tmp;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return iio_read_channel_raw(dac->dpot, val);

	case IIO_CHAN_INFO_SCALE:
		ret = iio_read_channel_scale(dac->dpot, val, val2);
		switch (ret) {
		case IIO_VAL_FRACTIONAL_LOG2:
			tmp = *val * 1000000000LL;
			do_div(tmp, dac->max_ohms);
			tmp *= regulator_get_voltage(dac->vref) / 1000;
			do_div(tmp, 1000000000LL);
			*val = tmp;
			return ret;
		case IIO_VAL_INT:
			/*
			 * Convert integer scale to fractional scale by
			 * setting the denominator (val2) to one, and...
			 */
			*val2 = 1;
			ret = IIO_VAL_FRACTIONAL;
			/* fall through */
		case IIO_VAL_FRACTIONAL:
			*val *= regulator_get_voltage(dac->vref) / 1000;
			*val2 *= dac->max_ohms;
			break;
		}

		return ret;
	}

	return -EINVAL;
}

static int dpot_dac_read_avail(struct iio_dev *indio_dev,
			       struct iio_chan_spec const *chan,
			       const int **vals, int *type, int *length,
			       long mask)
{
	struct dpot_dac *dac = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		*type = IIO_VAL_INT;
		return iio_read_avail_channel_raw(dac->dpot, vals, length);
	}

	return -EINVAL;
}

static int dpot_dac_write_raw(struct iio_dev *indio_dev,
			      struct iio_chan_spec const *chan,
			      int val, int val2, long mask)
{
	struct dpot_dac *dac = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return iio_write_channel_raw(dac->dpot, val);
	}

	return -EINVAL;
}

static const struct iio_info dpot_dac_info = {
	.read_raw = dpot_dac_read_raw,
	.read_avail = dpot_dac_read_avail,
	.write_raw = dpot_dac_write_raw,
};

static int dpot_dac_channel_max_ohms(struct iio_dev *indio_dev)
{
	struct device *dev = &indio_dev->dev;
	struct dpot_dac *dac = iio_priv(indio_dev);
	unsigned long long tmp;
	int ret;
	int val;
	int val2;
	int max;

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

	switch (iio_read_channel_scale(dac->dpot, &val, &val2)) {
	case IIO_VAL_INT:
		return max * val;
	case IIO_VAL_FRACTIONAL:
		tmp = (unsigned long long)max * val;
		do_div(tmp, val2);
		return tmp;
	case IIO_VAL_FRACTIONAL_LOG2:
		tmp = val * 1000000000LL * max >> val2;
		do_div(tmp, 1000000000LL);
		return tmp;
	default:
		dev_err(dev, "dpot has a scale that is too weird\n");
	}

	return -EINVAL;
}

static int dpot_dac_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct iio_dev *indio_dev;
	struct dpot_dac *dac;
	enum iio_chan_type type;
	int ret;

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

	platform_set_drvdata(pdev, indio_dev);
	dac = iio_priv(indio_dev);

	indio_dev->name = dev_name(dev);
	indio_dev->dev.parent = dev;
	indio_dev->info = &dpot_dac_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = &dpot_dac_iio_channel;
	indio_dev->num_channels = 1;

	dac->vref = devm_regulator_get(dev, "vref");
	if (IS_ERR(dac->vref)) {
		if (PTR_ERR(dac->vref) != -EPROBE_DEFER)
			dev_err(&pdev->dev, "failed to get vref regulator\n");
		return PTR_ERR(dac->vref);
	}

	dac->dpot = devm_iio_channel_get(dev, "dpot");
	if (IS_ERR(dac->dpot)) {
		if (PTR_ERR(dac->dpot) != -EPROBE_DEFER)
			dev_err(dev, "failed to get dpot input channel\n");
		return PTR_ERR(dac->dpot);
	}

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

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

	ret = dpot_dac_channel_max_ohms(indio_dev);
	if (ret < 0)
		return ret;
	dac->max_ohms = ret;

	ret = regulator_enable(dac->vref);
	if (ret) {
		dev_err(dev, "failed to enable the vref regulator\n");
		return ret;
	}

	ret = iio_device_register(indio_dev);
	if (ret) {
		dev_err(dev, "failed to register iio device\n");
		goto disable_reg;
	}

	return 0;

disable_reg:
	regulator_disable(dac->vref);
	return ret;
}

static int dpot_dac_remove(struct platform_device *pdev)
{
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct dpot_dac *dac = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	regulator_disable(dac->vref);

	return 0;
}

static const struct of_device_id dpot_dac_match[] = {
	{ .compatible = "dpot-dac" },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, dpot_dac_match);

static struct platform_driver dpot_dac_driver = {
	.probe = dpot_dac_probe,
	.remove = dpot_dac_remove,
	.driver = {
		.name = "iio-dpot-dac",
		.of_match_table = dpot_dac_match,
	},
};
module_platform_driver(dpot_dac_driver);

MODULE_DESCRIPTION("DAC emulation driver using a digital potentiometer");
MODULE_AUTHOR("Peter Rosin <[email protected]>");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
3c4b0f4d	1	// SPDX-License-Identifier: GPL-2.0
7fde1484 PR	2	/*
	3	* IIO DAC emulation driver using a digital potentiometer
	4	*
	5	* Copyright (C) 2016 Axentia Technologies AB
	6	*
	7	* Author: Peter Rosin <[email protected]>
7fde1484 PR	8	*/
	9
	10	/*
	11	* It is assumed that the dpot is used as a voltage divider between the
	12	* current dpot wiper setting and the maximum resistance of the dpot. The
	13	* divided voltage is provided by a vref regulator.
	14	*
	15	* .------.
	16	* .-----------. \| \|
	17	* \| vref \|--' .---.
	18	* \| regulator \|--. \| \|
	19	* '-----------' \| \| d \|
	20	* \| \| p \|
	21	* \| \| o \| wiper
	22	* \| \| t \|<---------+
	23	* \| \| \|
	24	* \| '---' dac output voltage
	25	* \| \|
	26	* '------+------------+
	27	*/
	28
	29	#include <linux/err.h>
	30	#include <linux/iio/consumer.h>
	31	#include <linux/iio/iio.h>
	32	#include <linux/module.h>
	33	#include <linux/of.h>
	34	#include <linux/platform_device.h>
	35	#include <linux/regulator/consumer.h>
	36
	37	struct dpot_dac {
	38	struct regulator *vref;
	39	struct iio_channel *dpot;
	40	u32 max_ohms;
	41	};
	42
	43	static const struct iio_chan_spec dpot_dac_iio_channel = {
	44	.type = IIO_VOLTAGE,
	45	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
	46	\| BIT(IIO_CHAN_INFO_SCALE),
	47	.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
	48	.output = 1,
	49	.indexed = 1,
	50	};
	51
	52	static int dpot_dac_read_raw(struct iio_dev *indio_dev,
	53	struct iio_chan_spec const *chan,
	54	int val, int val2, long mask)
	55	{
	56	struct dpot_dac *dac = iio_priv(indio_dev);
	57	int ret;
	58	unsigned long long tmp;
	59
	60	switch (mask) {
	61	case IIO_CHAN_INFO_RAW:
	62	return iio_read_channel_raw(dac->dpot, val);
	63
	64	case IIO_CHAN_INFO_SCALE:
	65	ret = iio_read_channel_scale(dac->dpot, val, val2);
	66	switch (ret) {
	67	case IIO_VAL_FRACTIONAL_LOG2:
	68	tmp = val 1000000000LL;
	69	do_div(tmp, dac->max_ohms);
	70	tmp *= regulator_get_voltage(dac->vref) / 1000;
	71	do_div(tmp, 1000000000LL);
72	*val = tmp;
73	return ret;
74	case IIO_VAL_INT:
75	/*
76	* Convert integer scale to fractional scale by
c65a0d84	77	* setting the denominator (val2) to one, and...
7fde1484 PR	78	*/
	79	*val2 = 1;
	80	ret = IIO_VAL_FRACTIONAL;
c65a0d84	81	/* fall through */
7fde1484 PR	82	case IIO_VAL_FRACTIONAL:
	83	val = regulator_get_voltage(dac->vref) / 1000;
	84	val2 = dac->max_ohms;
	85	break;
	86	}
	87
	88	return ret;
	89	}
	90
	91	return -EINVAL;
	92	}
	93
	94	static int dpot_dac_read_avail(struct iio_dev *indio_dev,
	95	struct iio_chan_spec const *chan,
	96	const int *vals, int type, int *length,
	97	long mask)
	98	{
	99	struct dpot_dac *dac = iio_priv(indio_dev);
	100
	101	switch (mask) {
	102	case IIO_CHAN_INFO_RAW:
	103	*type = IIO_VAL_INT;
	104	return iio_read_avail_channel_raw(dac->dpot, vals, length);
	105	}
	106
	107	return -EINVAL;
	108	}
	109
	110	static int dpot_dac_write_raw(struct iio_dev *indio_dev,
	111	struct iio_chan_spec const *chan,
	112	int val, int val2, long mask)
	113	{
	114	struct dpot_dac *dac = iio_priv(indio_dev);
	115
	116	switch (mask) {
	117	case IIO_CHAN_INFO_RAW:
	118	return iio_write_channel_raw(dac->dpot, val);
	119	}
	120
	121	return -EINVAL;
	122	}
	123
	124	static const struct iio_info dpot_dac_info = {
	125	.read_raw = dpot_dac_read_raw,
	126	.read_avail = dpot_dac_read_avail,
	127	.write_raw = dpot_dac_write_raw,
7fde1484 PR	128	};
	129
	130	static int dpot_dac_channel_max_ohms(struct iio_dev *indio_dev)
	131	{
	132	struct device *dev = &indio_dev->dev;
	133	struct dpot_dac *dac = iio_priv(indio_dev);
	134	unsigned long long tmp;
	135	int ret;
	136	int val;
	137	int val2;
	138	int max;
	139
	140	ret = iio_read_max_channel_raw(dac->dpot, &max);
	141	if (ret < 0) {
	142	dev_err(dev, "dpot does not indicate its raw maximum value\n");
	143	return ret;
	144	}
	145
	146	switch (iio_read_channel_scale(dac->dpot, &val, &val2)) {
	147	case IIO_VAL_INT:
	148	return max * val;
	149	case IIO_VAL_FRACTIONAL:
	150	tmp = (unsigned long long)max * val;
	151	do_div(tmp, val2);
	152	return tmp;
	153	case IIO_VAL_FRACTIONAL_LOG2:
	154	tmp = val * 1000000000LL * max >> val2;
	155	do_div(tmp, 1000000000LL);
	156	return tmp;
	157	default:
	158	dev_err(dev, "dpot has a scale that is too weird\n");
	159	}
	160
	161	return -EINVAL;
	162	}
	163
	164	static int dpot_dac_probe(struct platform_device *pdev)
	165	{
	166	struct device *dev = &pdev->dev;
	167	struct iio_dev *indio_dev;
	168	struct dpot_dac *dac;
	169	enum iio_chan_type type;
	170	int ret;
	171
	172	indio_dev = devm_iio_device_alloc(dev, sizeof(*dac));
	173	if (!indio_dev)
	174	return -ENOMEM;
	175
	176	platform_set_drvdata(pdev, indio_dev);
	177	dac = iio_priv(indio_dev);
	178
	179	indio_dev->name = dev_name(dev);
	180	indio_dev->dev.parent = dev;
	181	indio_dev->info = &dpot_dac_info;
	182	indio_dev->modes = INDIO_DIRECT_MODE;
	183	indio_dev->channels = &dpot_dac_iio_channel;
	184	indio_dev->num_channels = 1;
	185
	186	dac->vref = devm_regulator_get(dev, "vref");
	187	if (IS_ERR(dac->vref)) {
	188	if (PTR_ERR(dac->vref) != -EPROBE_DEFER)
	189	dev_err(&pdev->dev, "failed to get vref regulator\n");
	190	return PTR_ERR(dac->vref);
	191	}
192
193	dac->dpot = devm_iio_channel_get(dev, "dpot");
194	if (IS_ERR(dac->dpot)) {
195	if (PTR_ERR(dac->dpot) != -EPROBE_DEFER)
196	dev_err(dev, "failed to get dpot input channel\n");
197	return PTR_ERR(dac->dpot);
198	}
199
200	ret = iio_get_channel_type(dac->dpot, &type);
201	if (ret < 0)
202	return ret;
203
204	if (type != IIO_RESISTANCE) {
205	dev_err(dev, "dpot is of the wrong type\n");
206	return -EINVAL;
207	}
208
209	ret = dpot_dac_channel_max_ohms(indio_dev);
210	if (ret < 0)
211	return ret;
212	dac->max_ohms = ret;
213
214	ret = regulator_enable(dac->vref);
215	if (ret) {
216	dev_err(dev, "failed to enable the vref regulator\n");
217	return ret;
218	}
219
220	ret = iio_device_register(indio_dev);
221	if (ret) {
222	dev_err(dev, "failed to register iio device\n");
223	goto disable_reg;
224	}
225
226	return 0;
227
228	disable_reg:
229	regulator_disable(dac->vref);
230	return ret;
231	}
232
233	static int dpot_dac_remove(struct platform_device *pdev)
234	{
235	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
236	struct dpot_dac *dac = iio_priv(indio_dev);
237
238	iio_device_unregister(indio_dev);
239	regulator_disable(dac->vref);
240
241	return 0;
242	}
243
244	static const struct of_device_id dpot_dac_match[] = {
245	{ .compatible = "dpot-dac" },
246	{ /* sentinel */ }
247	};
248	MODULE_DEVICE_TABLE(of, dpot_dac_match);
249
250	static struct platform_driver dpot_dac_driver = {
251	.probe = dpot_dac_probe,
252	.remove = dpot_dac_remove,
253	.driver = {
254	.name = "iio-dpot-dac",
255	.of_match_table = dpot_dac_match,
256	},
257	};
258	module_platform_driver(dpot_dac_driver);
259
260	MODULE_DESCRIPTION("DAC emulation driver using a digital potentiometer");
261	MODULE_AUTHOR("Peter Rosin <[email protected]>");
262	MODULE_LICENSE("GPL v2");