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Angelo Compagnucci07914c82013-09-02 15:00:00 +01001/*
2 * mcp3422.c - driver for the Microchip mcp3422/3/4 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 *
9 * This driver exports the value of analog input voltage to sysfs, the
10 * voltage unit is nV.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
16 */
17
18#include <linux/err.h>
19#include <linux/i2c.h>
20#include <linux/module.h>
21#include <linux/delay.h>
22#include <linux/sysfs.h>
23
24#include <linux/iio/iio.h>
25#include <linux/iio/sysfs.h>
26
27/* Masks */
28#define MCP3422_CHANNEL_MASK 0x60
29#define MCP3422_PGA_MASK 0x03
30#define MCP3422_SRATE_MASK 0x0C
31#define MCP3422_SRATE_240 0x0
32#define MCP3422_SRATE_60 0x1
33#define MCP3422_SRATE_15 0x2
34#define MCP3422_SRATE_3 0x3
35#define MCP3422_PGA_1 0
36#define MCP3422_PGA_2 1
37#define MCP3422_PGA_4 2
38#define MCP3422_PGA_8 3
39#define MCP3422_CONT_SAMPLING 0x10
40
41#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
42#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK)
43#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2)
44
45#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
46#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
47#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
48
49#define MCP3422_CHAN(_index) \
50 { \
51 .type = IIO_VOLTAGE, \
52 .indexed = 1, \
53 .channel = _index, \
54 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
55 | BIT(IIO_CHAN_INFO_SCALE), \
56 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
57 }
58
59/* LSB is in nV to eliminate floating point */
60static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
61
62/*
63 * scales calculated as:
64 * rates_to_lsb[sample_rate] / (1 << pga);
65 * pga is 1 for 0, 2
66 */
67
68static const int mcp3422_scales[4][4] = {
69 { 1000000, 250000, 62500, 15625 },
70 { 500000 , 125000, 31250, 7812 },
71 { 250000 , 62500 , 15625, 3906 },
72 { 125000 , 31250 , 7812 , 1953 } };
73
74/* Constant msleep times for data acquisitions */
75static const int mcp3422_read_times[4] = {
76 [MCP3422_SRATE_240] = 1000 / 240,
77 [MCP3422_SRATE_60] = 1000 / 60,
78 [MCP3422_SRATE_15] = 1000 / 15,
79 [MCP3422_SRATE_3] = 1000 / 3 };
80
81/* sample rates to integer conversion table */
82static const int mcp3422_sample_rates[4] = {
83 [MCP3422_SRATE_240] = 240,
84 [MCP3422_SRATE_60] = 60,
85 [MCP3422_SRATE_15] = 15,
86 [MCP3422_SRATE_3] = 3 };
87
88/* sample rates to sign extension table */
89static const int mcp3422_sign_extend[4] = {
90 [MCP3422_SRATE_240] = 12,
91 [MCP3422_SRATE_60] = 14,
92 [MCP3422_SRATE_15] = 16,
93 [MCP3422_SRATE_3] = 18 };
94
95/* Client data (each client gets its own) */
96struct mcp3422 {
97 struct i2c_client *i2c;
98 u8 config;
99 u8 pga[4];
100 struct mutex lock;
101};
102
103static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
104{
105 int ret;
106
107 mutex_lock(&adc->lock);
108
109 ret = i2c_master_send(adc->i2c, &newconfig, 1);
110 if (ret > 0) {
111 adc->config = newconfig;
112 ret = 0;
113 }
114
115 mutex_unlock(&adc->lock);
116
117 return ret;
118}
119
120static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
121{
122 int ret = 0;
123 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
124 u8 buf[4] = {0, 0, 0, 0};
125 u32 temp;
126
127 if (sample_rate == MCP3422_SRATE_3) {
128 ret = i2c_master_recv(adc->i2c, buf, 4);
129 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
130 *config = buf[3];
131 } else {
132 ret = i2c_master_recv(adc->i2c, buf, 3);
133 temp = buf[0] << 8 | buf[1];
134 *config = buf[2];
135 }
136
137 *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
138
139 return ret;
140}
141
142static int mcp3422_read_channel(struct mcp3422 *adc,
143 struct iio_chan_spec const *channel, int *value)
144{
145 int ret;
146 u8 config;
147 u8 req_channel = channel->channel;
148
149 if (req_channel != MCP3422_CHANNEL(adc->config)) {
150 config = adc->config;
151 config &= ~MCP3422_CHANNEL_MASK;
152 config |= MCP3422_CHANNEL_VALUE(req_channel);
153 config &= ~MCP3422_PGA_MASK;
154 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
155 ret = mcp3422_update_config(adc, config);
156 if (ret < 0)
157 return ret;
158 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
159 }
160
161 return mcp3422_read(adc, value, &config);
162}
163
164static int mcp3422_read_raw(struct iio_dev *iio,
165 struct iio_chan_spec const *channel, int *val1,
166 int *val2, long mask)
167{
168 struct mcp3422 *adc = iio_priv(iio);
169 int err;
170
171 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
172 u8 pga = MCP3422_PGA(adc->config);
173
174 switch (mask) {
175 case IIO_CHAN_INFO_RAW:
176 err = mcp3422_read_channel(adc, channel, val1);
177 if (err < 0)
178 return -EINVAL;
179 return IIO_VAL_INT;
180
181 case IIO_CHAN_INFO_SCALE:
182
183 *val1 = 0;
184 *val2 = mcp3422_scales[sample_rate][pga];
185 return IIO_VAL_INT_PLUS_NANO;
186
187 case IIO_CHAN_INFO_SAMP_FREQ:
188 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
189 return IIO_VAL_INT;
190
191 default:
192 break;
193 }
194
195 return -EINVAL;
196}
197
198static int mcp3422_write_raw(struct iio_dev *iio,
199 struct iio_chan_spec const *channel, int val1,
200 int val2, long mask)
201{
202 struct mcp3422 *adc = iio_priv(iio);
203 u8 temp;
204 u8 config = adc->config;
205 u8 req_channel = channel->channel;
206 u8 sample_rate = MCP3422_SAMPLE_RATE(config);
207 u8 i;
208
209 switch (mask) {
210 case IIO_CHAN_INFO_SCALE:
211 if (val1 != 0)
212 return -EINVAL;
213
214 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
215 if (val2 == mcp3422_scales[sample_rate][i]) {
216 adc->pga[req_channel] = i;
217
218 config &= ~MCP3422_CHANNEL_MASK;
219 config |= MCP3422_CHANNEL_VALUE(req_channel);
220 config &= ~MCP3422_PGA_MASK;
221 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
222
223 return mcp3422_update_config(adc, config);
224 }
225 }
226 return -EINVAL;
227
228 case IIO_CHAN_INFO_SAMP_FREQ:
229 switch (val1) {
230 case 240:
231 temp = MCP3422_SRATE_240;
232 break;
233 case 60:
234 temp = MCP3422_SRATE_60;
235 break;
236 case 15:
237 temp = MCP3422_SRATE_15;
238 break;
239 case 3:
240 temp = MCP3422_SRATE_3;
241 break;
242 default:
243 return -EINVAL;
244 }
245
246 config &= ~MCP3422_CHANNEL_MASK;
247 config |= MCP3422_CHANNEL_VALUE(req_channel);
248 config &= ~MCP3422_SRATE_MASK;
249 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
250
251 return mcp3422_update_config(adc, config);
252
253 default:
254 break;
255 }
256
257 return -EINVAL;
258}
259
260static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
261 struct iio_chan_spec const *chan, long mask)
262{
263 switch (mask) {
264 case IIO_CHAN_INFO_SCALE:
265 return IIO_VAL_INT_PLUS_NANO;
266 case IIO_CHAN_INFO_SAMP_FREQ:
267 return IIO_VAL_INT_PLUS_MICRO;
268 default:
269 return -EINVAL;
270 }
271}
272
273static ssize_t mcp3422_show_scales(struct device *dev,
274 struct device_attribute *attr, char *buf)
275{
276 struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
277 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
278
279 return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
280 mcp3422_scales[sample_rate][0],
281 mcp3422_scales[sample_rate][1],
282 mcp3422_scales[sample_rate][2],
283 mcp3422_scales[sample_rate][3]);
284}
285
286static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3");
287static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
288 mcp3422_show_scales, NULL, 0);
289
290static struct attribute *mcp3422_attributes[] = {
291 &iio_const_attr_sampling_frequency_available.dev_attr.attr,
292 &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
293 NULL,
294};
295
296static const struct attribute_group mcp3422_attribute_group = {
297 .attrs = mcp3422_attributes,
298};
299
300static const struct iio_chan_spec mcp3422_channels[] = {
301 MCP3422_CHAN(0),
302 MCP3422_CHAN(1),
303};
304
305static const struct iio_chan_spec mcp3424_channels[] = {
306 MCP3422_CHAN(0),
307 MCP3422_CHAN(1),
308 MCP3422_CHAN(2),
309 MCP3422_CHAN(3),
310};
311
312static const struct iio_info mcp3422_info = {
313 .read_raw = mcp3422_read_raw,
314 .write_raw = mcp3422_write_raw,
315 .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
316 .attrs = &mcp3422_attribute_group,
317 .driver_module = THIS_MODULE,
318};
319
320static int mcp3422_probe(struct i2c_client *client,
321 const struct i2c_device_id *id)
322{
323 struct iio_dev *indio_dev;
324 struct mcp3422 *adc;
325 int err;
326 u8 config;
327
328 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
329 return -ENODEV;
330
331 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
332 if (!indio_dev)
333 return -ENOMEM;
334
335 adc = iio_priv(indio_dev);
336 adc->i2c = client;
337
338 mutex_init(&adc->lock);
339
340 indio_dev->dev.parent = &client->dev;
341 indio_dev->name = dev_name(&client->dev);
342 indio_dev->modes = INDIO_DIRECT_MODE;
343 indio_dev->info = &mcp3422_info;
344
345 switch ((unsigned int)(id->driver_data)) {
346 case 2:
347 case 3:
348 indio_dev->channels = mcp3422_channels;
349 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
350 break;
351 case 4:
352 indio_dev->channels = mcp3424_channels;
353 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
354 break;
355 }
356
357 /* meaningful default configuration */
358 config = (MCP3422_CONT_SAMPLING
359 | MCP3422_CHANNEL_VALUE(1)
360 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
361 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
362 mcp3422_update_config(adc, config);
363
364 err = iio_device_register(indio_dev);
365 if (err < 0)
366 return err;
367
368 i2c_set_clientdata(client, indio_dev);
369
370 return 0;
371}
372
373static int mcp3422_remove(struct i2c_client *client)
374{
375 iio_device_unregister(i2c_get_clientdata(client));
376 return 0;
377}
378
379static const struct i2c_device_id mcp3422_id[] = {
380 { "mcp3422", 2 },
381 { "mcp3423", 3 },
382 { "mcp3424", 4 },
383 { }
384};
385MODULE_DEVICE_TABLE(i2c, mcp3422_id);
386
387#ifdef CONFIG_OF
388static const struct of_device_id mcp3422_of_match[] = {
389 { .compatible = "mcp3422" },
390 { }
391};
392MODULE_DEVICE_TABLE(of, mcp3422_of_match);
393#endif
394
395static struct i2c_driver mcp3422_driver = {
396 .driver = {
397 .name = "mcp3422",
398 .owner = THIS_MODULE,
399 .of_match_table = of_match_ptr(mcp3422_of_match),
400 },
401 .probe = mcp3422_probe,
402 .remove = mcp3422_remove,
403 .id_table = mcp3422_id,
404};
405module_i2c_driver(mcp3422_driver);
406
407MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
408MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
409MODULE_LICENSE("GPL v2");