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Linux/drivers/iio/adc/mcp3422.c

  1 /*
  2  * mcp3422.c - driver for the Microchip mcp3422/3/4/6/7/8 chip family
  3  *
  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
  8  *            http://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
  9  *
 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>
 24 #include <linux/of.h>
 25 
 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 */
 62 static 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 
 70 static 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 */
 77 static 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 */
 84 static 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 */
 91 static const int mcp3422_sign_extend[4] = {
 92         [MCP3422_SRATE_240] = 11,
 93         [MCP3422_SRATE_60] = 13,
 94         [MCP3422_SRATE_15] = 15,
 95         [MCP3422_SRATE_3] = 17 };
 96 
 97 /* Client data (each client gets its own) */
 98 struct mcp3422 {
 99         struct i2c_client *i2c;
100         u8 id;
101         u8 config;
102         u8 pga[4];
103         struct mutex lock;
104 };
105 
106 static 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 
123 static 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 
145 static 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 
167 static 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 
201 static 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:
243                         if (adc->id > 4)
244                                 return -EINVAL;
245                         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 
265 static 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 
278 static 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 
289 static 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 
302 static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
303                 mcp3422_show_samp_freqs, NULL, 0);
304 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
305                 mcp3422_show_scales, NULL, 0);
306 
307 static struct attribute *mcp3422_attributes[] = {
308         &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
309         &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
310         NULL,
311 };
312 
313 static const struct attribute_group mcp3422_attribute_group = {
314         .attrs = mcp3422_attributes,
315 };
316 
317 static const struct iio_chan_spec mcp3422_channels[] = {
318         MCP3422_CHAN(0),
319         MCP3422_CHAN(1),
320 };
321 
322 static 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 
329 static 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 
337 static 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;
354         adc->id = (u8)(id->driver_data);
355 
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 
363         switch (adc->id) {
364         case 2:
365         case 3:
366         case 6:
367         case 7:
368                 indio_dev->channels = mcp3422_channels;
369                 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
370                 break;
371         case 4:
372         case 8:
373                 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 
385         err = devm_iio_device_register(&client->dev, indio_dev);
386         if (err < 0)
387                 return err;
388 
389         i2c_set_clientdata(client, indio_dev);
390 
391         return 0;
392 }
393 
394 static const struct i2c_device_id mcp3422_id[] = {
395         { "mcp3422", 2 },
396         { "mcp3423", 3 },
397         { "mcp3424", 4 },
398         { "mcp3426", 6 },
399         { "mcp3427", 7 },
400         { "mcp3428", 8 },
401         { }
402 };
403 MODULE_DEVICE_TABLE(i2c, mcp3422_id);
404 
405 #ifdef CONFIG_OF
406 static const struct of_device_id mcp3422_of_match[] = {
407         { .compatible = "mcp3422" },
408         { }
409 };
410 MODULE_DEVICE_TABLE(of, mcp3422_of_match);
411 #endif
412 
413 static 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,
420         .id_table = mcp3422_id,
421 };
422 module_i2c_driver(mcp3422_driver);
423 
424 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
425 MODULE_DESCRIPTION("Microchip mcp3422/3/4/6/7/8 driver");
426 MODULE_LICENSE("GPL v2");
427 

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