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Linux/drivers/iio/adc/mcp3422.c

  1 /*
  2  * mcp3422.c - driver for the Microchip mcp3421/2/3/4/5/6/7/8 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  *            http://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf
 10  *
 11  * This driver exports the value of analog input voltage to sysfs, the
 12  * voltage unit is nV.
 13  *
 14  * This program is free software; you can redistribute it and/or modify
 15  * it under the terms of the GNU General Public License as published by
 16  * the Free Software Foundation; either version 2 of the License, or
 17  * (at your option) any later version.
 18  */
 19 
 20 #include <linux/err.h>
 21 #include <linux/i2c.h>
 22 #include <linux/module.h>
 23 #include <linux/delay.h>
 24 #include <linux/sysfs.h>
 25 #include <linux/of.h>
 26 
 27 #include <linux/iio/iio.h>
 28 #include <linux/iio/sysfs.h>
 29 
 30 /* Masks */
 31 #define MCP3422_CHANNEL_MASK    0x60
 32 #define MCP3422_PGA_MASK        0x03
 33 #define MCP3422_SRATE_MASK      0x0C
 34 #define MCP3422_SRATE_240       0x0
 35 #define MCP3422_SRATE_60        0x1
 36 #define MCP3422_SRATE_15        0x2
 37 #define MCP3422_SRATE_3 0x3
 38 #define MCP3422_PGA_1   0
 39 #define MCP3422_PGA_2   1
 40 #define MCP3422_PGA_4   2
 41 #define MCP3422_PGA_8   3
 42 #define MCP3422_CONT_SAMPLING   0x10
 43 
 44 #define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
 45 #define MCP3422_PGA(config)     ((config) & MCP3422_PGA_MASK)
 46 #define MCP3422_SAMPLE_RATE(config)     (((config) & MCP3422_SRATE_MASK) >> 2)
 47 
 48 #define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
 49 #define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
 50 #define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
 51 
 52 #define MCP3422_CHAN(_index) \
 53         { \
 54                 .type = IIO_VOLTAGE, \
 55                 .indexed = 1, \
 56                 .channel = _index, \
 57                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
 58                                 | BIT(IIO_CHAN_INFO_SCALE), \
 59                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 60         }
 61 
 62 static const int mcp3422_scales[4][4] = {
 63         { 1000000, 500000, 250000, 125000 },
 64         { 250000,  125000, 62500,  31250  },
 65         { 62500,   31250,  15625,  7812   },
 66         { 15625,   7812,   3906,   1953   } };
 67 
 68 /* Constant msleep times for data acquisitions */
 69 static const int mcp3422_read_times[4] = {
 70         [MCP3422_SRATE_240] = 1000 / 240,
 71         [MCP3422_SRATE_60] = 1000 / 60,
 72         [MCP3422_SRATE_15] = 1000 / 15,
 73         [MCP3422_SRATE_3] = 1000 / 3 };
 74 
 75 /* sample rates to integer conversion table */
 76 static const int mcp3422_sample_rates[4] = {
 77         [MCP3422_SRATE_240] = 240,
 78         [MCP3422_SRATE_60] = 60,
 79         [MCP3422_SRATE_15] = 15,
 80         [MCP3422_SRATE_3] = 3 };
 81 
 82 /* sample rates to sign extension table */
 83 static const int mcp3422_sign_extend[4] = {
 84         [MCP3422_SRATE_240] = 11,
 85         [MCP3422_SRATE_60] = 13,
 86         [MCP3422_SRATE_15] = 15,
 87         [MCP3422_SRATE_3] = 17 };
 88 
 89 /* Client data (each client gets its own) */
 90 struct mcp3422 {
 91         struct i2c_client *i2c;
 92         u8 id;
 93         u8 config;
 94         u8 pga[4];
 95         struct mutex lock;
 96 };
 97 
 98 static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
 99 {
100         int ret;
101 
102         mutex_lock(&adc->lock);
103 
104         ret = i2c_master_send(adc->i2c, &newconfig, 1);
105         if (ret > 0) {
106                 adc->config = newconfig;
107                 ret = 0;
108         }
109 
110         mutex_unlock(&adc->lock);
111 
112         return ret;
113 }
114 
115 static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
116 {
117         int ret = 0;
118         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
119         u8 buf[4] = {0, 0, 0, 0};
120         u32 temp;
121 
122         if (sample_rate == MCP3422_SRATE_3) {
123                 ret = i2c_master_recv(adc->i2c, buf, 4);
124                 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
125                 *config = buf[3];
126         } else {
127                 ret = i2c_master_recv(adc->i2c, buf, 3);
128                 temp = buf[0] << 8 | buf[1];
129                 *config = buf[2];
130         }
131 
132         *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
133 
134         return ret;
135 }
136 
137 static int mcp3422_read_channel(struct mcp3422 *adc,
138                                 struct iio_chan_spec const *channel, int *value)
139 {
140         int ret;
141         u8 config;
142         u8 req_channel = channel->channel;
143 
144         if (req_channel != MCP3422_CHANNEL(adc->config)) {
145                 config = adc->config;
146                 config &= ~MCP3422_CHANNEL_MASK;
147                 config |= MCP3422_CHANNEL_VALUE(req_channel);
148                 config &= ~MCP3422_PGA_MASK;
149                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
150                 ret = mcp3422_update_config(adc, config);
151                 if (ret < 0)
152                         return ret;
153                 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
154         }
155 
156         return mcp3422_read(adc, value, &config);
157 }
158 
159 static int mcp3422_read_raw(struct iio_dev *iio,
160                         struct iio_chan_spec const *channel, int *val1,
161                         int *val2, long mask)
162 {
163         struct mcp3422 *adc = iio_priv(iio);
164         int err;
165 
166         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
167         u8 pga           = MCP3422_PGA(adc->config);
168 
169         switch (mask) {
170         case IIO_CHAN_INFO_RAW:
171                 err = mcp3422_read_channel(adc, channel, val1);
172                 if (err < 0)
173                         return -EINVAL;
174                 return IIO_VAL_INT;
175 
176         case IIO_CHAN_INFO_SCALE:
177 
178                 *val1 = 0;
179                 *val2 = mcp3422_scales[sample_rate][pga];
180                 return IIO_VAL_INT_PLUS_NANO;
181 
182         case IIO_CHAN_INFO_SAMP_FREQ:
183                 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
184                 return IIO_VAL_INT;
185 
186         default:
187                 break;
188         }
189 
190         return -EINVAL;
191 }
192 
193 static int mcp3422_write_raw(struct iio_dev *iio,
194                         struct iio_chan_spec const *channel, int val1,
195                         int val2, long mask)
196 {
197         struct mcp3422 *adc = iio_priv(iio);
198         u8 temp;
199         u8 config = adc->config;
200         u8 req_channel = channel->channel;
201         u8 sample_rate = MCP3422_SAMPLE_RATE(config);
202         u8 i;
203 
204         switch (mask) {
205         case IIO_CHAN_INFO_SCALE:
206                 if (val1 != 0)
207                         return -EINVAL;
208 
209                 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
210                         if (val2 == mcp3422_scales[sample_rate][i]) {
211                                 adc->pga[req_channel] = i;
212 
213                                 config &= ~MCP3422_CHANNEL_MASK;
214                                 config |= MCP3422_CHANNEL_VALUE(req_channel);
215                                 config &= ~MCP3422_PGA_MASK;
216                                 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
217 
218                                 return mcp3422_update_config(adc, config);
219                         }
220                 }
221                 return -EINVAL;
222 
223         case IIO_CHAN_INFO_SAMP_FREQ:
224                 switch (val1) {
225                 case 240:
226                         temp = MCP3422_SRATE_240;
227                         break;
228                 case 60:
229                         temp = MCP3422_SRATE_60;
230                         break;
231                 case 15:
232                         temp = MCP3422_SRATE_15;
233                         break;
234                 case 3:
235                         if (adc->id > 4)
236                                 return -EINVAL;
237                         temp = MCP3422_SRATE_3;
238                         break;
239                 default:
240                         return -EINVAL;
241                 }
242 
243                 config &= ~MCP3422_CHANNEL_MASK;
244                 config |= MCP3422_CHANNEL_VALUE(req_channel);
245                 config &= ~MCP3422_SRATE_MASK;
246                 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
247 
248                 return mcp3422_update_config(adc, config);
249 
250         default:
251                 break;
252         }
253 
254         return -EINVAL;
255 }
256 
257 static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
258                 struct iio_chan_spec const *chan, long mask)
259 {
260         switch (mask) {
261         case IIO_CHAN_INFO_SCALE:
262                 return IIO_VAL_INT_PLUS_NANO;
263         case IIO_CHAN_INFO_SAMP_FREQ:
264                 return IIO_VAL_INT_PLUS_MICRO;
265         default:
266                 return -EINVAL;
267         }
268 }
269 
270 static ssize_t mcp3422_show_samp_freqs(struct device *dev,
271                 struct device_attribute *attr, char *buf)
272 {
273         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
274 
275         if (adc->id > 4)
276                 return sprintf(buf, "240 60 15\n");
277 
278         return sprintf(buf, "240 60 15 3\n");
279 }
280 
281 static ssize_t mcp3422_show_scales(struct device *dev,
282                 struct device_attribute *attr, char *buf)
283 {
284         struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
285         u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
286 
287         return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
288                 mcp3422_scales[sample_rate][0],
289                 mcp3422_scales[sample_rate][1],
290                 mcp3422_scales[sample_rate][2],
291                 mcp3422_scales[sample_rate][3]);
292 }
293 
294 static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
295                 mcp3422_show_samp_freqs, NULL, 0);
296 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
297                 mcp3422_show_scales, NULL, 0);
298 
299 static struct attribute *mcp3422_attributes[] = {
300         &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
301         &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
302         NULL,
303 };
304 
305 static const struct attribute_group mcp3422_attribute_group = {
306         .attrs = mcp3422_attributes,
307 };
308 
309 static const struct iio_chan_spec mcp3421_channels[] = {
310         MCP3422_CHAN(0),
311 };
312 
313 static const struct iio_chan_spec mcp3422_channels[] = {
314         MCP3422_CHAN(0),
315         MCP3422_CHAN(1),
316 };
317 
318 static const struct iio_chan_spec mcp3424_channels[] = {
319         MCP3422_CHAN(0),
320         MCP3422_CHAN(1),
321         MCP3422_CHAN(2),
322         MCP3422_CHAN(3),
323 };
324 
325 static const struct iio_info mcp3422_info = {
326         .read_raw = mcp3422_read_raw,
327         .write_raw = mcp3422_write_raw,
328         .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
329         .attrs = &mcp3422_attribute_group,
330         .driver_module = THIS_MODULE,
331 };
332 
333 static int mcp3422_probe(struct i2c_client *client,
334                          const struct i2c_device_id *id)
335 {
336         struct iio_dev *indio_dev;
337         struct mcp3422 *adc;
338         int err;
339         u8 config;
340 
341         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
342                 return -EOPNOTSUPP;
343 
344         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
345         if (!indio_dev)
346                 return -ENOMEM;
347 
348         adc = iio_priv(indio_dev);
349         adc->i2c = client;
350         adc->id = (u8)(id->driver_data);
351 
352         mutex_init(&adc->lock);
353 
354         indio_dev->dev.parent = &client->dev;
355         indio_dev->name = dev_name(&client->dev);
356         indio_dev->modes = INDIO_DIRECT_MODE;
357         indio_dev->info = &mcp3422_info;
358 
359         switch (adc->id) {
360         case 1:
361         case 5:
362                 indio_dev->channels = mcp3421_channels;
363                 indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
364                 break;
365         case 2:
366         case 3:
367         case 6:
368         case 7:
369                 indio_dev->channels = mcp3422_channels;
370                 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
371                 break;
372         case 4:
373         case 8:
374                 indio_dev->channels = mcp3424_channels;
375                 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
376                 break;
377         }
378 
379         /* meaningful default configuration */
380         config = (MCP3422_CONT_SAMPLING
381                 | MCP3422_CHANNEL_VALUE(1)
382                 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
383                 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
384         mcp3422_update_config(adc, config);
385 
386         err = devm_iio_device_register(&client->dev, indio_dev);
387         if (err < 0)
388                 return err;
389 
390         i2c_set_clientdata(client, indio_dev);
391 
392         return 0;
393 }
394 
395 static const struct i2c_device_id mcp3422_id[] = {
396         { "mcp3421", 1 },
397         { "mcp3422", 2 },
398         { "mcp3423", 3 },
399         { "mcp3424", 4 },
400         { "mcp3425", 5 },
401         { "mcp3426", 6 },
402         { "mcp3427", 7 },
403         { "mcp3428", 8 },
404         { }
405 };
406 MODULE_DEVICE_TABLE(i2c, mcp3422_id);
407 
408 #ifdef CONFIG_OF
409 static const struct of_device_id mcp3422_of_match[] = {
410         { .compatible = "mcp3422" },
411         { }
412 };
413 MODULE_DEVICE_TABLE(of, mcp3422_of_match);
414 #endif
415 
416 static struct i2c_driver mcp3422_driver = {
417         .driver = {
418                 .name = "mcp3422",
419                 .of_match_table = of_match_ptr(mcp3422_of_match),
420         },
421         .probe = mcp3422_probe,
422         .id_table = mcp3422_id,
423 };
424 module_i2c_driver(mcp3422_driver);
425 
426 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
427 MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
428 MODULE_LICENSE("GPL v2");
429 

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