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1 | /* |
2 | * ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver | |
3 | * | |
4 | * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com> | |
5 | * | |
6 | * This file is subject to the terms and conditions of version 2 of | |
7 | * the GNU General Public License. See the file COPYING in the main | |
8 | * directory of this archive for more details. | |
9 | * | |
10 | * Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/spi/spi.h> | |
15 | #include <linux/iio/iio.h> | |
16 | #include <linux/regulator/consumer.h> | |
17 | ||
18 | enum { | |
19 | adc0831, | |
20 | adc0832, | |
21 | adc0834, | |
22 | adc0838, | |
23 | }; | |
24 | ||
25 | struct adc0832 { | |
26 | struct spi_device *spi; | |
27 | struct regulator *reg; | |
28 | struct mutex lock; | |
29 | u8 mux_bits; | |
30 | ||
31 | u8 tx_buf[2] ____cacheline_aligned; | |
32 | u8 rx_buf[2]; | |
33 | }; | |
34 | ||
35 | #define ADC0832_VOLTAGE_CHANNEL(chan) \ | |
36 | { \ | |
37 | .type = IIO_VOLTAGE, \ | |
38 | .indexed = 1, \ | |
39 | .channel = chan, \ | |
40 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ | |
41 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ | |
42 | } | |
43 | ||
44 | #define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2) \ | |
45 | { \ | |
46 | .type = IIO_VOLTAGE, \ | |
47 | .indexed = 1, \ | |
48 | .channel = (chan1), \ | |
49 | .channel2 = (chan2), \ | |
50 | .differential = 1, \ | |
51 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ | |
52 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ | |
53 | } | |
54 | ||
55 | static const struct iio_chan_spec adc0831_channels[] = { | |
56 | ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), | |
57 | }; | |
58 | ||
59 | static const struct iio_chan_spec adc0832_channels[] = { | |
60 | ADC0832_VOLTAGE_CHANNEL(0), | |
61 | ADC0832_VOLTAGE_CHANNEL(1), | |
62 | ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), | |
63 | ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), | |
64 | }; | |
65 | ||
66 | static const struct iio_chan_spec adc0834_channels[] = { | |
67 | ADC0832_VOLTAGE_CHANNEL(0), | |
68 | ADC0832_VOLTAGE_CHANNEL(1), | |
69 | ADC0832_VOLTAGE_CHANNEL(2), | |
70 | ADC0832_VOLTAGE_CHANNEL(3), | |
71 | ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), | |
72 | ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), | |
73 | ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3), | |
74 | ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2), | |
75 | }; | |
76 | ||
77 | static const struct iio_chan_spec adc0838_channels[] = { | |
78 | ADC0832_VOLTAGE_CHANNEL(0), | |
79 | ADC0832_VOLTAGE_CHANNEL(1), | |
80 | ADC0832_VOLTAGE_CHANNEL(2), | |
81 | ADC0832_VOLTAGE_CHANNEL(3), | |
82 | ADC0832_VOLTAGE_CHANNEL(4), | |
83 | ADC0832_VOLTAGE_CHANNEL(5), | |
84 | ADC0832_VOLTAGE_CHANNEL(6), | |
85 | ADC0832_VOLTAGE_CHANNEL(7), | |
86 | ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), | |
87 | ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), | |
88 | ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3), | |
89 | ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2), | |
90 | ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5), | |
91 | ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4), | |
92 | ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7), | |
93 | ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6), | |
94 | }; | |
95 | ||
96 | static int adc0831_adc_conversion(struct adc0832 *adc) | |
97 | { | |
98 | struct spi_device *spi = adc->spi; | |
99 | int ret; | |
100 | ||
101 | ret = spi_read(spi, &adc->rx_buf, 2); | |
102 | if (ret) | |
103 | return ret; | |
104 | ||
105 | /* | |
106 | * Skip TRI-STATE and a leading zero | |
107 | */ | |
108 | return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6); | |
109 | } | |
110 | ||
111 | static int adc0832_adc_conversion(struct adc0832 *adc, int channel, | |
112 | bool differential) | |
113 | { | |
114 | struct spi_device *spi = adc->spi; | |
115 | struct spi_transfer xfer = { | |
116 | .tx_buf = adc->tx_buf, | |
117 | .rx_buf = adc->rx_buf, | |
118 | .len = 2, | |
119 | }; | |
120 | int ret; | |
121 | ||
122 | if (!adc->mux_bits) | |
123 | return adc0831_adc_conversion(adc); | |
124 | ||
125 | /* start bit */ | |
126 | adc->tx_buf[0] = 1 << (adc->mux_bits + 1); | |
127 | /* single-ended or differential */ | |
128 | adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits); | |
129 | /* odd / sign */ | |
130 | adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1); | |
131 | /* select */ | |
132 | if (adc->mux_bits > 1) | |
133 | adc->tx_buf[0] |= channel / 2; | |
134 | ||
135 | /* align Data output BIT7 (MSB) to 8-bit boundary */ | |
136 | adc->tx_buf[0] <<= 1; | |
137 | ||
138 | ret = spi_sync_transfer(spi, &xfer, 1); | |
139 | if (ret) | |
140 | return ret; | |
141 | ||
142 | return adc->rx_buf[1]; | |
143 | } | |
144 | ||
145 | static int adc0832_read_raw(struct iio_dev *iio, | |
146 | struct iio_chan_spec const *channel, int *value, | |
147 | int *shift, long mask) | |
148 | { | |
149 | struct adc0832 *adc = iio_priv(iio); | |
150 | ||
151 | switch (mask) { | |
152 | case IIO_CHAN_INFO_RAW: | |
153 | mutex_lock(&adc->lock); | |
154 | *value = adc0832_adc_conversion(adc, channel->channel, | |
155 | channel->differential); | |
156 | mutex_unlock(&adc->lock); | |
157 | if (*value < 0) | |
158 | return *value; | |
159 | ||
160 | return IIO_VAL_INT; | |
161 | case IIO_CHAN_INFO_SCALE: | |
162 | *value = regulator_get_voltage(adc->reg); | |
163 | if (*value < 0) | |
164 | return *value; | |
165 | ||
166 | /* convert regulator output voltage to mV */ | |
167 | *value /= 1000; | |
168 | *shift = 8; | |
169 | ||
170 | return IIO_VAL_FRACTIONAL_LOG2; | |
171 | } | |
172 | ||
173 | return -EINVAL; | |
174 | } | |
175 | ||
176 | static const struct iio_info adc0832_info = { | |
177 | .read_raw = adc0832_read_raw, | |
178 | .driver_module = THIS_MODULE, | |
179 | }; | |
180 | ||
181 | static int adc0832_probe(struct spi_device *spi) | |
182 | { | |
183 | struct iio_dev *indio_dev; | |
184 | struct adc0832 *adc; | |
185 | int ret; | |
186 | ||
187 | indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); | |
188 | if (!indio_dev) | |
189 | return -ENOMEM; | |
190 | ||
191 | adc = iio_priv(indio_dev); | |
192 | adc->spi = spi; | |
193 | mutex_init(&adc->lock); | |
194 | ||
195 | indio_dev->name = spi_get_device_id(spi)->name; | |
196 | indio_dev->dev.parent = &spi->dev; | |
197 | indio_dev->info = &adc0832_info; | |
198 | indio_dev->modes = INDIO_DIRECT_MODE; | |
199 | ||
200 | switch (spi_get_device_id(spi)->driver_data) { | |
201 | case adc0831: | |
202 | adc->mux_bits = 0; | |
203 | indio_dev->channels = adc0831_channels; | |
204 | indio_dev->num_channels = ARRAY_SIZE(adc0831_channels); | |
205 | break; | |
206 | case adc0832: | |
207 | adc->mux_bits = 1; | |
208 | indio_dev->channels = adc0832_channels; | |
209 | indio_dev->num_channels = ARRAY_SIZE(adc0832_channels); | |
210 | break; | |
211 | case adc0834: | |
212 | adc->mux_bits = 2; | |
213 | indio_dev->channels = adc0834_channels; | |
214 | indio_dev->num_channels = ARRAY_SIZE(adc0834_channels); | |
215 | break; | |
216 | case adc0838: | |
217 | adc->mux_bits = 3; | |
218 | indio_dev->channels = adc0838_channels; | |
219 | indio_dev->num_channels = ARRAY_SIZE(adc0838_channels); | |
220 | break; | |
221 | default: | |
222 | return -EINVAL; | |
223 | } | |
224 | ||
225 | adc->reg = devm_regulator_get(&spi->dev, "vref"); | |
226 | if (IS_ERR(adc->reg)) | |
227 | return PTR_ERR(adc->reg); | |
228 | ||
229 | ret = regulator_enable(adc->reg); | |
230 | if (ret) | |
231 | return ret; | |
232 | ||
233 | spi_set_drvdata(spi, indio_dev); | |
234 | ||
235 | ret = iio_device_register(indio_dev); | |
236 | if (ret) | |
237 | regulator_disable(adc->reg); | |
238 | ||
239 | return ret; | |
240 | } | |
241 | ||
242 | static int adc0832_remove(struct spi_device *spi) | |
243 | { | |
244 | struct iio_dev *indio_dev = spi_get_drvdata(spi); | |
245 | struct adc0832 *adc = iio_priv(indio_dev); | |
246 | ||
247 | iio_device_unregister(indio_dev); | |
248 | regulator_disable(adc->reg); | |
249 | ||
250 | return 0; | |
251 | } | |
252 | ||
253 | #ifdef CONFIG_OF | |
254 | ||
255 | static const struct of_device_id adc0832_dt_ids[] = { | |
256 | { .compatible = "ti,adc0831", }, | |
257 | { .compatible = "ti,adc0832", }, | |
258 | { .compatible = "ti,adc0834", }, | |
259 | { .compatible = "ti,adc0838", }, | |
260 | {} | |
261 | }; | |
262 | MODULE_DEVICE_TABLE(of, adc0832_dt_ids); | |
263 | ||
264 | #endif | |
265 | ||
266 | static const struct spi_device_id adc0832_id[] = { | |
267 | { "adc0831", adc0831 }, | |
268 | { "adc0832", adc0832 }, | |
269 | { "adc0834", adc0834 }, | |
270 | { "adc0838", adc0838 }, | |
271 | {} | |
272 | }; | |
273 | MODULE_DEVICE_TABLE(spi, adc0832_id); | |
274 | ||
275 | static struct spi_driver adc0832_driver = { | |
276 | .driver = { | |
277 | .name = "adc0832", | |
278 | .of_match_table = of_match_ptr(adc0832_dt_ids), | |
279 | }, | |
280 | .probe = adc0832_probe, | |
281 | .remove = adc0832_remove, | |
282 | .id_table = adc0832_id, | |
283 | }; | |
284 | module_spi_driver(adc0832_driver); | |
285 | ||
286 | MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>"); | |
287 | MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver"); | |
288 | MODULE_LICENSE("GPL v2"); |