xref: /openbmc/linux/drivers/iio/dac/ad8801.c (revision e5bd61e8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * IIO DAC driver for Analog Devices AD8801 DAC
4  *
5  * Copyright (C) 2016 Gwenhael Goavec-Merou
6  */
7 
8 #include <linux/iio/iio.h>
9 #include <linux/module.h>
10 #include <linux/regulator/consumer.h>
11 #include <linux/spi/spi.h>
12 #include <linux/sysfs.h>
13 
14 #define AD8801_CFG_ADDR_OFFSET 8
15 
16 enum ad8801_device_ids {
17 	ID_AD8801,
18 	ID_AD8803,
19 };
20 
21 struct ad8801_state {
22 	struct spi_device *spi;
23 	unsigned char dac_cache[8]; /* Value write on each channel */
24 	unsigned int vrefh_mv;
25 	unsigned int vrefl_mv;
26 	struct regulator *vrefh_reg;
27 	struct regulator *vrefl_reg;
28 
29 	__be16 data ____cacheline_aligned;
30 };
31 
32 static int ad8801_spi_write(struct ad8801_state *state,
33 	u8 channel, unsigned char value)
34 {
35 	state->data = cpu_to_be16((channel << AD8801_CFG_ADDR_OFFSET) | value);
36 	return spi_write(state->spi, &state->data, sizeof(state->data));
37 }
38 
39 static int ad8801_write_raw(struct iio_dev *indio_dev,
40 	struct iio_chan_spec const *chan, int val, int val2, long mask)
41 {
42 	struct ad8801_state *state = iio_priv(indio_dev);
43 	int ret;
44 
45 	switch (mask) {
46 	case IIO_CHAN_INFO_RAW:
47 		if (val >= 256 || val < 0)
48 			return -EINVAL;
49 
50 		ret = ad8801_spi_write(state, chan->channel, val);
51 		if (ret == 0)
52 			state->dac_cache[chan->channel] = val;
53 		break;
54 	default:
55 		ret = -EINVAL;
56 	}
57 
58 	return ret;
59 }
60 
61 static int ad8801_read_raw(struct iio_dev *indio_dev,
62 	struct iio_chan_spec const *chan, int *val, int *val2, long info)
63 {
64 	struct ad8801_state *state = iio_priv(indio_dev);
65 
66 	switch (info) {
67 	case IIO_CHAN_INFO_RAW:
68 		*val = state->dac_cache[chan->channel];
69 		return IIO_VAL_INT;
70 	case IIO_CHAN_INFO_SCALE:
71 		*val = state->vrefh_mv - state->vrefl_mv;
72 		*val2 = 8;
73 		return IIO_VAL_FRACTIONAL_LOG2;
74 	case IIO_CHAN_INFO_OFFSET:
75 		*val = state->vrefl_mv;
76 		return IIO_VAL_INT;
77 	default:
78 		return -EINVAL;
79 	}
80 
81 	return -EINVAL;
82 }
83 
84 static const struct iio_info ad8801_info = {
85 	.read_raw = ad8801_read_raw,
86 	.write_raw = ad8801_write_raw,
87 };
88 
89 #define AD8801_CHANNEL(chan) {		\
90 	.type = IIO_VOLTAGE,			\
91 	.indexed = 1,				\
92 	.output = 1,				\
93 	.channel = chan,			\
94 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
95 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
96 		BIT(IIO_CHAN_INFO_OFFSET), \
97 }
98 
99 static const struct iio_chan_spec ad8801_channels[] = {
100 	AD8801_CHANNEL(0),
101 	AD8801_CHANNEL(1),
102 	AD8801_CHANNEL(2),
103 	AD8801_CHANNEL(3),
104 	AD8801_CHANNEL(4),
105 	AD8801_CHANNEL(5),
106 	AD8801_CHANNEL(6),
107 	AD8801_CHANNEL(7),
108 };
109 
110 static int ad8801_probe(struct spi_device *spi)
111 {
112 	struct iio_dev *indio_dev;
113 	struct ad8801_state *state;
114 	const struct spi_device_id *id;
115 	int ret;
116 
117 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
118 	if (indio_dev == NULL)
119 		return -ENOMEM;
120 
121 	state = iio_priv(indio_dev);
122 	state->spi = spi;
123 	id = spi_get_device_id(spi);
124 
125 	state->vrefh_reg = devm_regulator_get(&spi->dev, "vrefh");
126 	if (IS_ERR(state->vrefh_reg)) {
127 		dev_err(&spi->dev, "Vrefh regulator not specified\n");
128 		return PTR_ERR(state->vrefh_reg);
129 	}
130 
131 	ret = regulator_enable(state->vrefh_reg);
132 	if (ret) {
133 		dev_err(&spi->dev, "Failed to enable vrefh regulator: %d\n",
134 				ret);
135 		return ret;
136 	}
137 
138 	ret = regulator_get_voltage(state->vrefh_reg);
139 	if (ret < 0) {
140 		dev_err(&spi->dev, "Failed to read vrefh regulator: %d\n",
141 				ret);
142 		goto error_disable_vrefh_reg;
143 	}
144 	state->vrefh_mv = ret / 1000;
145 
146 	if (id->driver_data == ID_AD8803) {
147 		state->vrefl_reg = devm_regulator_get(&spi->dev, "vrefl");
148 		if (IS_ERR(state->vrefl_reg)) {
149 			dev_err(&spi->dev, "Vrefl regulator not specified\n");
150 			ret = PTR_ERR(state->vrefl_reg);
151 			goto error_disable_vrefh_reg;
152 		}
153 
154 		ret = regulator_enable(state->vrefl_reg);
155 		if (ret) {
156 			dev_err(&spi->dev, "Failed to enable vrefl regulator: %d\n",
157 					ret);
158 			goto error_disable_vrefh_reg;
159 		}
160 
161 		ret = regulator_get_voltage(state->vrefl_reg);
162 		if (ret < 0) {
163 			dev_err(&spi->dev, "Failed to read vrefl regulator: %d\n",
164 					ret);
165 			goto error_disable_vrefl_reg;
166 		}
167 		state->vrefl_mv = ret / 1000;
168 	} else {
169 		state->vrefl_mv = 0;
170 		state->vrefl_reg = NULL;
171 	}
172 
173 	spi_set_drvdata(spi, indio_dev);
174 	indio_dev->info = &ad8801_info;
175 	indio_dev->modes = INDIO_DIRECT_MODE;
176 	indio_dev->channels = ad8801_channels;
177 	indio_dev->num_channels = ARRAY_SIZE(ad8801_channels);
178 	indio_dev->name = id->name;
179 
180 	ret = iio_device_register(indio_dev);
181 	if (ret) {
182 		dev_err(&spi->dev, "Failed to register iio device: %d\n",
183 				ret);
184 		goto error_disable_vrefl_reg;
185 	}
186 
187 	return 0;
188 
189 error_disable_vrefl_reg:
190 	if (state->vrefl_reg)
191 		regulator_disable(state->vrefl_reg);
192 error_disable_vrefh_reg:
193 	regulator_disable(state->vrefh_reg);
194 	return ret;
195 }
196 
197 static int ad8801_remove(struct spi_device *spi)
198 {
199 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
200 	struct ad8801_state *state = iio_priv(indio_dev);
201 
202 	iio_device_unregister(indio_dev);
203 	if (state->vrefl_reg)
204 		regulator_disable(state->vrefl_reg);
205 	regulator_disable(state->vrefh_reg);
206 
207 	return 0;
208 }
209 
210 static const struct spi_device_id ad8801_ids[] = {
211 	{"ad8801", ID_AD8801},
212 	{"ad8803", ID_AD8803},
213 	{}
214 };
215 MODULE_DEVICE_TABLE(spi, ad8801_ids);
216 
217 static struct spi_driver ad8801_driver = {
218 	.driver = {
219 		.name	= "ad8801",
220 	},
221 	.probe		= ad8801_probe,
222 	.remove		= ad8801_remove,
223 	.id_table	= ad8801_ids,
224 };
225 module_spi_driver(ad8801_driver);
226 
227 MODULE_AUTHOR("Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>");
228 MODULE_DESCRIPTION("Analog Devices AD8801/AD8803 DAC");
229 MODULE_LICENSE("GPL v2");
230