1 // SPDX-License-Identifier: GPL-2.0
3  * IIO DAC emulation driver using a digital potentiometer
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
15  *                   .------.
16  *    .-----------.  |      |
17  *    | vref      |--'    .---.
18  *    | regulator |--.    |   |
19  *    '-----------'  |    | d |
22  *                   |    | t |<---------+
24  *                   |    '---'       dac output voltage
26  *                   '------+------------+
39 	struct iio_channel *dpot;  member
56 	struct dpot_dac *dac = iio_priv(indio_dev);  in dpot_dac_read_raw()  local
62 		return iio_read_channel_raw(dac->dpot, val);  in dpot_dac_read_raw()
65 		ret = iio_read_channel_scale(dac->dpot, val, val2);  in dpot_dac_read_raw()
69 			do_div(tmp, dac->max_ohms);  in dpot_dac_read_raw()
70 			tmp *= regulator_get_voltage(dac->vref) / 1000;  in dpot_dac_read_raw()
84 			*val *= regulator_get_voltage(dac->vref) / 1000;  in dpot_dac_read_raw()
85 			*val2 *= dac->max_ohms;  in dpot_dac_read_raw()
92 	return -EINVAL;  in dpot_dac_read_raw()
100 	struct dpot_dac *dac = iio_priv(indio_dev);  in dpot_dac_read_avail()  local
105 		return iio_read_avail_channel_raw(dac->dpot, vals, length);  in dpot_dac_read_avail()
108 	return -EINVAL;  in dpot_dac_read_avail()
115 	struct dpot_dac *dac = iio_priv(indio_dev);  in dpot_dac_write_raw()  local
119 		return iio_write_channel_raw(dac->dpot, val);  in dpot_dac_write_raw()
122 	return -EINVAL;  in dpot_dac_write_raw()
133 	struct device *dev = &indio_dev->dev;  in dpot_dac_channel_max_ohms()
134 	struct dpot_dac *dac = iio_priv(indio_dev);  in dpot_dac_channel_max_ohms()  local
141 	ret = iio_read_max_channel_raw(dac->dpot, &max);  in dpot_dac_channel_max_ohms()
143 		dev_err(dev, "dpot does not indicate its raw maximum value\n");  in dpot_dac_channel_max_ohms()
147 	switch (iio_read_channel_scale(dac->dpot, &val, &val2)) {  in dpot_dac_channel_max_ohms()
159 		dev_err(dev, "dpot has a scale that is too weird\n");  in dpot_dac_channel_max_ohms()
162 	return -EINVAL;  in dpot_dac_channel_max_ohms()
167 	struct device *dev = &pdev->dev;  in dpot_dac_probe()
169 	struct dpot_dac *dac;  in dpot_dac_probe()  local
173 	indio_dev = devm_iio_device_alloc(dev, sizeof(*dac));  in dpot_dac_probe()
175 		return -ENOMEM;  in dpot_dac_probe()
178 	dac = iio_priv(indio_dev);  in dpot_dac_probe()
180 	indio_dev->name = dev_name(dev);  in dpot_dac_probe()
181 	indio_dev->info = &dpot_dac_info;  in dpot_dac_probe()
182 	indio_dev->modes = INDIO_DIRECT_MODE;  in dpot_dac_probe()
183 	indio_dev->channels = &dpot_dac_iio_channel;  in dpot_dac_probe()
184 	indio_dev->num_channels = 1;  in dpot_dac_probe()
186 	dac->vref = devm_regulator_get(dev, "vref");  in dpot_dac_probe()
187 	if (IS_ERR(dac->vref))  in dpot_dac_probe()
188 		return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref),  in dpot_dac_probe()
191 	dac->dpot = devm_iio_channel_get(dev, "dpot");  in dpot_dac_probe()
192 	if (IS_ERR(dac->dpot))  in dpot_dac_probe()
193 		return dev_err_probe(&pdev->dev, PTR_ERR(dac->dpot),  in dpot_dac_probe()
194 				     "failed to get dpot input channel\n");  in dpot_dac_probe()
196 	ret = iio_get_channel_type(dac->dpot, &type);  in dpot_dac_probe()
201 		dev_err(dev, "dpot is of the wrong type\n");  in dpot_dac_probe()
202 		return -EINVAL;  in dpot_dac_probe()
208 	dac->max_ohms = ret;  in dpot_dac_probe()
210 	ret = regulator_enable(dac->vref);  in dpot_dac_probe()
225 	regulator_disable(dac->vref);  in dpot_dac_probe()
232 	struct dpot_dac *dac = iio_priv(indio_dev);  in dpot_dac_remove()  local
235 	regulator_disable(dac->vref);  in dpot_dac_remove()
239 	{ .compatible = "dpot-dac" },
248 		.name = "iio-dpot-dac",
254 MODULE_DESCRIPTION("DAC emulation driver using a digital potentiometer");