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Angelo Compagnucci07914c82013-09-02 15:00:00 +01001/*
Angelo Compagnucci2816ac62014-08-03 23:22:00 +01002 * mcp3422.c - driver for the Microchip mcp3422/3/4/6/7/8 chip family
Angelo Compagnucci07914c82013-09-02 15:00:00 +01003 *
4 * Copyright (C) 2013, Angelo Compagnucci
5 * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
6 *
7 * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
Angelo Compagnucci2816ac62014-08-03 23:22:00 +01008 * http://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
Angelo Compagnucci07914c82013-09-02 15:00:00 +01009 *
10 * This driver exports the value of analog input voltage to sysfs, the
11 * voltage unit is nV.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 */
18
19#include <linux/err.h>
20#include <linux/i2c.h>
21#include <linux/module.h>
22#include <linux/delay.h>
23#include <linux/sysfs.h>
Sachin Kamatde36d812013-10-18 13:04:00 +010024#include <linux/of.h>
Angelo Compagnucci07914c82013-09-02 15:00:00 +010025
26#include <linux/iio/iio.h>
27#include <linux/iio/sysfs.h>
28
29/* Masks */
30#define MCP3422_CHANNEL_MASK 0x60
31#define MCP3422_PGA_MASK 0x03
32#define MCP3422_SRATE_MASK 0x0C
33#define MCP3422_SRATE_240 0x0
34#define MCP3422_SRATE_60 0x1
35#define MCP3422_SRATE_15 0x2
36#define MCP3422_SRATE_3 0x3
37#define MCP3422_PGA_1 0
38#define MCP3422_PGA_2 1
39#define MCP3422_PGA_4 2
40#define MCP3422_PGA_8 3
41#define MCP3422_CONT_SAMPLING 0x10
42
43#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
44#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK)
45#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2)
46
47#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
48#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
49#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
50
51#define MCP3422_CHAN(_index) \
52 { \
53 .type = IIO_VOLTAGE, \
54 .indexed = 1, \
55 .channel = _index, \
56 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
57 | BIT(IIO_CHAN_INFO_SCALE), \
58 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
59 }
60
61/* LSB is in nV to eliminate floating point */
62static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
63
64/*
65 * scales calculated as:
66 * rates_to_lsb[sample_rate] / (1 << pga);
67 * pga is 1 for 0, 2
68 */
69
70static const int mcp3422_scales[4][4] = {
71 { 1000000, 250000, 62500, 15625 },
72 { 500000 , 125000, 31250, 7812 },
73 { 250000 , 62500 , 15625, 3906 },
74 { 125000 , 31250 , 7812 , 1953 } };
75
76/* Constant msleep times for data acquisitions */
77static const int mcp3422_read_times[4] = {
78 [MCP3422_SRATE_240] = 1000 / 240,
79 [MCP3422_SRATE_60] = 1000 / 60,
80 [MCP3422_SRATE_15] = 1000 / 15,
81 [MCP3422_SRATE_3] = 1000 / 3 };
82
83/* sample rates to integer conversion table */
84static const int mcp3422_sample_rates[4] = {
85 [MCP3422_SRATE_240] = 240,
86 [MCP3422_SRATE_60] = 60,
87 [MCP3422_SRATE_15] = 15,
88 [MCP3422_SRATE_3] = 3 };
89
90/* sample rates to sign extension table */
91static const int mcp3422_sign_extend[4] = {
Peter Meerwalda5a3e432013-11-02 19:44:00 +000092 [MCP3422_SRATE_240] = 11,
93 [MCP3422_SRATE_60] = 13,
94 [MCP3422_SRATE_15] = 15,
95 [MCP3422_SRATE_3] = 17 };
Angelo Compagnucci07914c82013-09-02 15:00:00 +010096
97/* Client data (each client gets its own) */
98struct mcp3422 {
99 struct i2c_client *i2c;
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100100 u8 id;
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100101 u8 config;
102 u8 pga[4];
103 struct mutex lock;
104};
105
106static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
107{
108 int ret;
109
110 mutex_lock(&adc->lock);
111
112 ret = i2c_master_send(adc->i2c, &newconfig, 1);
113 if (ret > 0) {
114 adc->config = newconfig;
115 ret = 0;
116 }
117
118 mutex_unlock(&adc->lock);
119
120 return ret;
121}
122
123static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
124{
125 int ret = 0;
126 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
127 u8 buf[4] = {0, 0, 0, 0};
128 u32 temp;
129
130 if (sample_rate == MCP3422_SRATE_3) {
131 ret = i2c_master_recv(adc->i2c, buf, 4);
132 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
133 *config = buf[3];
134 } else {
135 ret = i2c_master_recv(adc->i2c, buf, 3);
136 temp = buf[0] << 8 | buf[1];
137 *config = buf[2];
138 }
139
140 *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
141
142 return ret;
143}
144
145static int mcp3422_read_channel(struct mcp3422 *adc,
146 struct iio_chan_spec const *channel, int *value)
147{
148 int ret;
149 u8 config;
150 u8 req_channel = channel->channel;
151
152 if (req_channel != MCP3422_CHANNEL(adc->config)) {
153 config = adc->config;
154 config &= ~MCP3422_CHANNEL_MASK;
155 config |= MCP3422_CHANNEL_VALUE(req_channel);
156 config &= ~MCP3422_PGA_MASK;
157 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
158 ret = mcp3422_update_config(adc, config);
159 if (ret < 0)
160 return ret;
161 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
162 }
163
164 return mcp3422_read(adc, value, &config);
165}
166
167static int mcp3422_read_raw(struct iio_dev *iio,
168 struct iio_chan_spec const *channel, int *val1,
169 int *val2, long mask)
170{
171 struct mcp3422 *adc = iio_priv(iio);
172 int err;
173
174 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
175 u8 pga = MCP3422_PGA(adc->config);
176
177 switch (mask) {
178 case IIO_CHAN_INFO_RAW:
179 err = mcp3422_read_channel(adc, channel, val1);
180 if (err < 0)
181 return -EINVAL;
182 return IIO_VAL_INT;
183
184 case IIO_CHAN_INFO_SCALE:
185
186 *val1 = 0;
187 *val2 = mcp3422_scales[sample_rate][pga];
188 return IIO_VAL_INT_PLUS_NANO;
189
190 case IIO_CHAN_INFO_SAMP_FREQ:
191 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
192 return IIO_VAL_INT;
193
194 default:
195 break;
196 }
197
198 return -EINVAL;
199}
200
201static int mcp3422_write_raw(struct iio_dev *iio,
202 struct iio_chan_spec const *channel, int val1,
203 int val2, long mask)
204{
205 struct mcp3422 *adc = iio_priv(iio);
206 u8 temp;
207 u8 config = adc->config;
208 u8 req_channel = channel->channel;
209 u8 sample_rate = MCP3422_SAMPLE_RATE(config);
210 u8 i;
211
212 switch (mask) {
213 case IIO_CHAN_INFO_SCALE:
214 if (val1 != 0)
215 return -EINVAL;
216
217 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
218 if (val2 == mcp3422_scales[sample_rate][i]) {
219 adc->pga[req_channel] = i;
220
221 config &= ~MCP3422_CHANNEL_MASK;
222 config |= MCP3422_CHANNEL_VALUE(req_channel);
223 config &= ~MCP3422_PGA_MASK;
224 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
225
226 return mcp3422_update_config(adc, config);
227 }
228 }
229 return -EINVAL;
230
231 case IIO_CHAN_INFO_SAMP_FREQ:
232 switch (val1) {
233 case 240:
234 temp = MCP3422_SRATE_240;
235 break;
236 case 60:
237 temp = MCP3422_SRATE_60;
238 break;
239 case 15:
240 temp = MCP3422_SRATE_15;
241 break;
242 case 3:
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100243 if (adc->id > 4)
244 return -EINVAL;
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100245 temp = MCP3422_SRATE_3;
246 break;
247 default:
248 return -EINVAL;
249 }
250
251 config &= ~MCP3422_CHANNEL_MASK;
252 config |= MCP3422_CHANNEL_VALUE(req_channel);
253 config &= ~MCP3422_SRATE_MASK;
254 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
255
256 return mcp3422_update_config(adc, config);
257
258 default:
259 break;
260 }
261
262 return -EINVAL;
263}
264
265static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
266 struct iio_chan_spec const *chan, long mask)
267{
268 switch (mask) {
269 case IIO_CHAN_INFO_SCALE:
270 return IIO_VAL_INT_PLUS_NANO;
271 case IIO_CHAN_INFO_SAMP_FREQ:
272 return IIO_VAL_INT_PLUS_MICRO;
273 default:
274 return -EINVAL;
275 }
276}
277
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100278static ssize_t mcp3422_show_samp_freqs(struct device *dev,
279 struct device_attribute *attr, char *buf)
280{
281 struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
282
283 if (adc->id > 4)
284 return sprintf(buf, "240 60 15\n");
285
286 return sprintf(buf, "240 60 15 3\n");
287}
288
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100289static ssize_t mcp3422_show_scales(struct device *dev,
290 struct device_attribute *attr, char *buf)
291{
292 struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
293 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
294
295 return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
296 mcp3422_scales[sample_rate][0],
297 mcp3422_scales[sample_rate][1],
298 mcp3422_scales[sample_rate][2],
299 mcp3422_scales[sample_rate][3]);
300}
301
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100302static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
303 mcp3422_show_samp_freqs, NULL, 0);
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100304static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
305 mcp3422_show_scales, NULL, 0);
306
307static struct attribute *mcp3422_attributes[] = {
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100308 &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100309 &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
310 NULL,
311};
312
313static const struct attribute_group mcp3422_attribute_group = {
314 .attrs = mcp3422_attributes,
315};
316
317static const struct iio_chan_spec mcp3422_channels[] = {
318 MCP3422_CHAN(0),
319 MCP3422_CHAN(1),
320};
321
322static const struct iio_chan_spec mcp3424_channels[] = {
323 MCP3422_CHAN(0),
324 MCP3422_CHAN(1),
325 MCP3422_CHAN(2),
326 MCP3422_CHAN(3),
327};
328
329static const struct iio_info mcp3422_info = {
330 .read_raw = mcp3422_read_raw,
331 .write_raw = mcp3422_write_raw,
332 .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
333 .attrs = &mcp3422_attribute_group,
334 .driver_module = THIS_MODULE,
335};
336
337static int mcp3422_probe(struct i2c_client *client,
338 const struct i2c_device_id *id)
339{
340 struct iio_dev *indio_dev;
341 struct mcp3422 *adc;
342 int err;
343 u8 config;
344
345 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
346 return -ENODEV;
347
348 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
349 if (!indio_dev)
350 return -ENOMEM;
351
352 adc = iio_priv(indio_dev);
353 adc->i2c = client;
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100354 adc->id = (u8)(id->driver_data);
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100355
356 mutex_init(&adc->lock);
357
358 indio_dev->dev.parent = &client->dev;
359 indio_dev->name = dev_name(&client->dev);
360 indio_dev->modes = INDIO_DIRECT_MODE;
361 indio_dev->info = &mcp3422_info;
362
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100363 switch (adc->id) {
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100364 case 2:
365 case 3:
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100366 case 6:
367 case 7:
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100368 indio_dev->channels = mcp3422_channels;
369 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
370 break;
371 case 4:
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100372 case 8:
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100373 indio_dev->channels = mcp3424_channels;
374 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
375 break;
376 }
377
378 /* meaningful default configuration */
379 config = (MCP3422_CONT_SAMPLING
380 | MCP3422_CHANNEL_VALUE(1)
381 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
382 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
383 mcp3422_update_config(adc, config);
384
Sachin Kamat2842d4c2013-10-29 11:39:00 +0000385 err = devm_iio_device_register(&client->dev, indio_dev);
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100386 if (err < 0)
387 return err;
388
389 i2c_set_clientdata(client, indio_dev);
390
391 return 0;
392}
393
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100394static const struct i2c_device_id mcp3422_id[] = {
395 { "mcp3422", 2 },
396 { "mcp3423", 3 },
397 { "mcp3424", 4 },
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100398 { "mcp3426", 6 },
399 { "mcp3427", 7 },
400 { "mcp3428", 8 },
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100401 { }
402};
403MODULE_DEVICE_TABLE(i2c, mcp3422_id);
404
405#ifdef CONFIG_OF
406static const struct of_device_id mcp3422_of_match[] = {
407 { .compatible = "mcp3422" },
408 { }
409};
410MODULE_DEVICE_TABLE(of, mcp3422_of_match);
411#endif
412
413static struct i2c_driver mcp3422_driver = {
414 .driver = {
415 .name = "mcp3422",
416 .owner = THIS_MODULE,
417 .of_match_table = of_match_ptr(mcp3422_of_match),
418 },
419 .probe = mcp3422_probe,
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100420 .id_table = mcp3422_id,
421};
422module_i2c_driver(mcp3422_driver);
423
424MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
Angelo Compagnucci2816ac62014-08-03 23:22:00 +0100425MODULE_DESCRIPTION("Microchip mcp3422/3/4/6/7/8 driver");
Angelo Compagnucci07914c82013-09-02 15:00:00 +0100426MODULE_LICENSE("GPL v2");