1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver
4 *
5 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>
6 *
7 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf
8 *
9 * SPI interface connections
10 *
11 * SPI MAXIM
12 * Master Direction MAX1117/8/9
13 * ------ --------- -----------
14 * nCS --> CNVST
15 * SCK --> SCLK
16 * MISO <-- DOUT
17 * ------ --------- -----------
18 */
19
20 #include <linux/module.h>
21 #include <linux/mod_devicetable.h>
22 #include <linux/spi/spi.h>
23 #include <linux/iio/iio.h>
24 #include <linux/iio/buffer.h>
25 #include <linux/iio/triggered_buffer.h>
26 #include <linux/iio/trigger_consumer.h>
27 #include <linux/regulator/consumer.h>
28
29 enum max1118_id {
30 max1117,
31 max1118,
32 max1119,
33 };
34
35 struct max1118 {
36 struct spi_device *spi;
37 struct mutex lock;
38 struct regulator *reg;
39 /* Ensure natural alignment of buffer elements */
40 struct {
41 u8 channels[2];
42 s64 ts __aligned(8);
43 } scan;
44
45 u8 data __aligned(IIO_DMA_MINALIGN);
46 };
47
48 #define MAX1118_CHANNEL(ch) \
49 { \
50 .type = IIO_VOLTAGE, \
51 .indexed = 1, \
52 .channel = (ch), \
53 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
54 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
55 .scan_index = ch, \
56 .scan_type = { \
57 .sign = 'u', \
58 .realbits = 8, \
59 .storagebits = 8, \
60 }, \
61 }
62
63 static const struct iio_chan_spec max1118_channels[] = {
64 MAX1118_CHANNEL(0),
65 MAX1118_CHANNEL(1),
66 IIO_CHAN_SOFT_TIMESTAMP(2),
67 };
68
max1118_read(struct iio_dev * indio_dev,int channel)69 static int max1118_read(struct iio_dev *indio_dev, int channel)
70 {
71 struct max1118 *adc = iio_priv(indio_dev);
72 struct spi_transfer xfers[] = {
73 /*
74 * To select CH1 for conversion, CNVST pin must be brought high
75 * and low for a second time.
76 */
77 {
78 .len = 0,
79 .delay = { /* > CNVST Low Time 100 ns */
80 .value = 1,
81 .unit = SPI_DELAY_UNIT_USECS
82 },
83 .cs_change = 1,
84 },
85 /*
86 * The acquisition interval begins with the falling edge of
87 * CNVST. The total acquisition and conversion process takes
88 * <7.5us.
89 */
90 {
91 .len = 0,
92 .delay = {
93 .value = 8,
94 .unit = SPI_DELAY_UNIT_USECS
95 },
96 },
97 {
98 .rx_buf = &adc->data,
99 .len = 1,
100 },
101 };
102 int ret;
103
104 if (channel == 0)
105 ret = spi_sync_transfer(adc->spi, xfers + 1, 2);
106 else
107 ret = spi_sync_transfer(adc->spi, xfers, 3);
108
109 if (ret)
110 return ret;
111
112 return adc->data;
113 }
114
max1118_get_vref_mV(struct iio_dev * indio_dev)115 static int max1118_get_vref_mV(struct iio_dev *indio_dev)
116 {
117 struct max1118 *adc = iio_priv(indio_dev);
118 const struct spi_device_id *id = spi_get_device_id(adc->spi);
119 int vref_uV;
120
121 switch (id->driver_data) {
122 case max1117:
123 return 2048;
124 case max1119:
125 return 4096;
126 case max1118:
127 vref_uV = regulator_get_voltage(adc->reg);
128 if (vref_uV < 0)
129 return vref_uV;
130 return vref_uV / 1000;
131 }
132
133 return -ENODEV;
134 }
135
max1118_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)136 static int max1118_read_raw(struct iio_dev *indio_dev,
137 struct iio_chan_spec const *chan,
138 int *val, int *val2, long mask)
139 {
140 struct max1118 *adc = iio_priv(indio_dev);
141
142 switch (mask) {
143 case IIO_CHAN_INFO_RAW:
144 mutex_lock(&adc->lock);
145 *val = max1118_read(indio_dev, chan->channel);
146 mutex_unlock(&adc->lock);
147 if (*val < 0)
148 return *val;
149
150 return IIO_VAL_INT;
151 case IIO_CHAN_INFO_SCALE:
152 *val = max1118_get_vref_mV(indio_dev);
153 if (*val < 0)
154 return *val;
155 *val2 = 8;
156
157 return IIO_VAL_FRACTIONAL_LOG2;
158 }
159
160 return -EINVAL;
161 }
162
163 static const struct iio_info max1118_info = {
164 .read_raw = max1118_read_raw,
165 };
166
max1118_trigger_handler(int irq,void * p)167 static irqreturn_t max1118_trigger_handler(int irq, void *p)
168 {
169 struct iio_poll_func *pf = p;
170 struct iio_dev *indio_dev = pf->indio_dev;
171 struct max1118 *adc = iio_priv(indio_dev);
172 int scan_index;
173 int i = 0;
174
175 mutex_lock(&adc->lock);
176
177 for_each_set_bit(scan_index, indio_dev->active_scan_mask,
178 indio_dev->masklength) {
179 const struct iio_chan_spec *scan_chan =
180 &indio_dev->channels[scan_index];
181 int ret = max1118_read(indio_dev, scan_chan->channel);
182
183 if (ret < 0) {
184 dev_warn(&adc->spi->dev,
185 "failed to get conversion data\n");
186 goto out;
187 }
188
189 adc->scan.channels[i] = ret;
190 i++;
191 }
192 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
193 iio_get_time_ns(indio_dev));
194 out:
195 mutex_unlock(&adc->lock);
196
197 iio_trigger_notify_done(indio_dev->trig);
198
199 return IRQ_HANDLED;
200 }
201
max1118_reg_disable(void * reg)202 static void max1118_reg_disable(void *reg)
203 {
204 regulator_disable(reg);
205 }
206
max1118_probe(struct spi_device * spi)207 static int max1118_probe(struct spi_device *spi)
208 {
209 struct iio_dev *indio_dev;
210 struct max1118 *adc;
211 const struct spi_device_id *id = spi_get_device_id(spi);
212 int ret;
213
214 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
215 if (!indio_dev)
216 return -ENOMEM;
217
218 adc = iio_priv(indio_dev);
219 adc->spi = spi;
220 mutex_init(&adc->lock);
221
222 if (id->driver_data == max1118) {
223 adc->reg = devm_regulator_get(&spi->dev, "vref");
224 if (IS_ERR(adc->reg))
225 return dev_err_probe(&spi->dev, PTR_ERR(adc->reg),
226 "failed to get vref regulator\n");
227 ret = regulator_enable(adc->reg);
228 if (ret)
229 return ret;
230
231 ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable,
232 adc->reg);
233 if (ret)
234 return ret;
235
236 }
237
238 indio_dev->name = spi_get_device_id(spi)->name;
239 indio_dev->info = &max1118_info;
240 indio_dev->modes = INDIO_DIRECT_MODE;
241 indio_dev->channels = max1118_channels;
242 indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
243
244 /*
245 * To reinitiate a conversion on CH0, it is necessary to allow for a
246 * conversion to be complete and all of the data to be read out. Once
247 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
248 * into AutoShutdown mode until the next conversion is initiated.
249 */
250 max1118_read(indio_dev, 0);
251
252 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
253 max1118_trigger_handler, NULL);
254 if (ret)
255 return ret;
256
257 return devm_iio_device_register(&spi->dev, indio_dev);
258 }
259
260 static const struct spi_device_id max1118_id[] = {
261 { "max1117", max1117 },
262 { "max1118", max1118 },
263 { "max1119", max1119 },
264 {}
265 };
266 MODULE_DEVICE_TABLE(spi, max1118_id);
267
268 static const struct of_device_id max1118_dt_ids[] = {
269 { .compatible = "maxim,max1117" },
270 { .compatible = "maxim,max1118" },
271 { .compatible = "maxim,max1119" },
272 {},
273 };
274 MODULE_DEVICE_TABLE(of, max1118_dt_ids);
275
276 static struct spi_driver max1118_spi_driver = {
277 .driver = {
278 .name = "max1118",
279 .of_match_table = max1118_dt_ids,
280 },
281 .probe = max1118_probe,
282 .id_table = max1118_id,
283 };
284 module_spi_driver(max1118_spi_driver);
285
286 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
287 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
288 MODULE_LICENSE("GPL v2");
289
