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 <[email protected]>
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 aligned_s64 ts;
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 iio_for_each_active_channel(indio_dev, scan_index) {
178 const struct iio_chan_spec *scan_chan =
179 &indio_dev->channels[scan_index];
180 int ret = max1118_read(indio_dev, scan_chan->channel);
181
182 if (ret < 0) {
183 dev_warn(&adc->spi->dev,
184 "failed to get conversion data\n");
185 goto out;
186 }
187
188 adc->scan.channels[i] = ret;
189 i++;
190 }
191 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
192 iio_get_time_ns(indio_dev));
193 out:
194 mutex_unlock(&adc->lock);
195
196 iio_trigger_notify_done(indio_dev->trig);
197
198 return IRQ_HANDLED;
199 }
200
max1118_reg_disable(void * reg)201 static void max1118_reg_disable(void *reg)
202 {
203 regulator_disable(reg);
204 }
205
max1118_probe(struct spi_device * spi)206 static int max1118_probe(struct spi_device *spi)
207 {
208 struct iio_dev *indio_dev;
209 struct max1118 *adc;
210 const struct spi_device_id *id = spi_get_device_id(spi);
211 int ret;
212
213 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
214 if (!indio_dev)
215 return -ENOMEM;
216
217 adc = iio_priv(indio_dev);
218 adc->spi = spi;
219 mutex_init(&adc->lock);
220
221 if (id->driver_data == max1118) {
222 adc->reg = devm_regulator_get(&spi->dev, "vref");
223 if (IS_ERR(adc->reg))
224 return dev_err_probe(&spi->dev, PTR_ERR(adc->reg),
225 "failed to get vref regulator\n");
226 ret = regulator_enable(adc->reg);
227 if (ret)
228 return ret;
229
230 ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable,
231 adc->reg);
232 if (ret)
233 return ret;
234
235 }
236
237 indio_dev->name = spi_get_device_id(spi)->name;
238 indio_dev->info = &max1118_info;
239 indio_dev->modes = INDIO_DIRECT_MODE;
240 indio_dev->channels = max1118_channels;
241 indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
242
243 /*
244 * To reinitiate a conversion on CH0, it is necessary to allow for a
245 * conversion to be complete and all of the data to be read out. Once
246 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
247 * into AutoShutdown mode until the next conversion is initiated.
248 */
249 max1118_read(indio_dev, 0);
250
251 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
252 max1118_trigger_handler, NULL);
253 if (ret)
254 return ret;
255
256 return devm_iio_device_register(&spi->dev, indio_dev);
257 }
258
259 static const struct spi_device_id max1118_id[] = {
260 { "max1117", max1117 },
261 { "max1118", max1118 },
262 { "max1119", max1119 },
263 { }
264 };
265 MODULE_DEVICE_TABLE(spi, max1118_id);
266
267 static const struct of_device_id max1118_dt_ids[] = {
268 { .compatible = "maxim,max1117" },
269 { .compatible = "maxim,max1118" },
270 { .compatible = "maxim,max1119" },
271 { }
272 };
273 MODULE_DEVICE_TABLE(of, max1118_dt_ids);
274
275 static struct spi_driver max1118_spi_driver = {
276 .driver = {
277 .name = "max1118",
278 .of_match_table = max1118_dt_ids,
279 },
280 .probe = max1118_probe,
281 .id_table = max1118_id,
282 };
283 module_spi_driver(max1118_spi_driver);
284
285 MODULE_AUTHOR("Akinobu Mita <[email protected]>");
286 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
287 MODULE_LICENSE("GPL v2");
288