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Linux kernel mirror (for testing)
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linux
1/*
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#include <linux/of.h>
24
25#include <linux/iio/iio.h>
26#include <linux/iio/sysfs.h>
27
28/* Masks */
29#define MCP3422_CHANNEL_MASK 0x60
30#define MCP3422_PGA_MASK 0x03
31#define MCP3422_SRATE_MASK 0x0C
32#define MCP3422_SRATE_240 0x0
33#define MCP3422_SRATE_60 0x1
34#define MCP3422_SRATE_15 0x2
35#define MCP3422_SRATE_3 0x3
36#define MCP3422_PGA_1 0
37#define MCP3422_PGA_2 1
38#define MCP3422_PGA_4 2
39#define MCP3422_PGA_8 3
40#define MCP3422_CONT_SAMPLING 0x10
41
42#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
43#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK)
44#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2)
45
46#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
47#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
48#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
49
50#define MCP3422_CHAN(_index) \
51 { \
52 .type = IIO_VOLTAGE, \
53 .indexed = 1, \
54 .channel = _index, \
55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
56 | BIT(IIO_CHAN_INFO_SCALE), \
57 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
58 }
59
60/* LSB is in nV to eliminate floating point */
61static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
62
63/*
64 * scales calculated as:
65 * rates_to_lsb[sample_rate] / (1 << pga);
66 * pga is 1 for 0, 2
67 */
68
69static const int mcp3422_scales[4][4] = {
70 { 1000000, 250000, 62500, 15625 },
71 { 500000 , 125000, 31250, 7812 },
72 { 250000 , 62500 , 15625, 3906 },
73 { 125000 , 31250 , 7812 , 1953 } };
74
75/* Constant msleep times for data acquisitions */
76static const int mcp3422_read_times[4] = {
77 [MCP3422_SRATE_240] = 1000 / 240,
78 [MCP3422_SRATE_60] = 1000 / 60,
79 [MCP3422_SRATE_15] = 1000 / 15,
80 [MCP3422_SRATE_3] = 1000 / 3 };
81
82/* sample rates to integer conversion table */
83static const int mcp3422_sample_rates[4] = {
84 [MCP3422_SRATE_240] = 240,
85 [MCP3422_SRATE_60] = 60,
86 [MCP3422_SRATE_15] = 15,
87 [MCP3422_SRATE_3] = 3 };
88
89/* sample rates to sign extension table */
90static const int mcp3422_sign_extend[4] = {
91 [MCP3422_SRATE_240] = 11,
92 [MCP3422_SRATE_60] = 13,
93 [MCP3422_SRATE_15] = 15,
94 [MCP3422_SRATE_3] = 17 };
95
96/* Client data (each client gets its own) */
97struct mcp3422 {
98 struct i2c_client *i2c;
99 u8 config;
100 u8 pga[4];
101 struct mutex lock;
102};
103
104static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
105{
106 int ret;
107
108 mutex_lock(&adc->lock);
109
110 ret = i2c_master_send(adc->i2c, &newconfig, 1);
111 if (ret > 0) {
112 adc->config = newconfig;
113 ret = 0;
114 }
115
116 mutex_unlock(&adc->lock);
117
118 return ret;
119}
120
121static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
122{
123 int ret = 0;
124 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
125 u8 buf[4] = {0, 0, 0, 0};
126 u32 temp;
127
128 if (sample_rate == MCP3422_SRATE_3) {
129 ret = i2c_master_recv(adc->i2c, buf, 4);
130 temp = buf[0] << 16 | buf[1] << 8 | buf[2];
131 *config = buf[3];
132 } else {
133 ret = i2c_master_recv(adc->i2c, buf, 3);
134 temp = buf[0] << 8 | buf[1];
135 *config = buf[2];
136 }
137
138 *value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
139
140 return ret;
141}
142
143static int mcp3422_read_channel(struct mcp3422 *adc,
144 struct iio_chan_spec const *channel, int *value)
145{
146 int ret;
147 u8 config;
148 u8 req_channel = channel->channel;
149
150 if (req_channel != MCP3422_CHANNEL(adc->config)) {
151 config = adc->config;
152 config &= ~MCP3422_CHANNEL_MASK;
153 config |= MCP3422_CHANNEL_VALUE(req_channel);
154 config &= ~MCP3422_PGA_MASK;
155 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
156 ret = mcp3422_update_config(adc, config);
157 if (ret < 0)
158 return ret;
159 msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
160 }
161
162 return mcp3422_read(adc, value, &config);
163}
164
165static int mcp3422_read_raw(struct iio_dev *iio,
166 struct iio_chan_spec const *channel, int *val1,
167 int *val2, long mask)
168{
169 struct mcp3422 *adc = iio_priv(iio);
170 int err;
171
172 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
173 u8 pga = MCP3422_PGA(adc->config);
174
175 switch (mask) {
176 case IIO_CHAN_INFO_RAW:
177 err = mcp3422_read_channel(adc, channel, val1);
178 if (err < 0)
179 return -EINVAL;
180 return IIO_VAL_INT;
181
182 case IIO_CHAN_INFO_SCALE:
183
184 *val1 = 0;
185 *val2 = mcp3422_scales[sample_rate][pga];
186 return IIO_VAL_INT_PLUS_NANO;
187
188 case IIO_CHAN_INFO_SAMP_FREQ:
189 *val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
190 return IIO_VAL_INT;
191
192 default:
193 break;
194 }
195
196 return -EINVAL;
197}
198
199static int mcp3422_write_raw(struct iio_dev *iio,
200 struct iio_chan_spec const *channel, int val1,
201 int val2, long mask)
202{
203 struct mcp3422 *adc = iio_priv(iio);
204 u8 temp;
205 u8 config = adc->config;
206 u8 req_channel = channel->channel;
207 u8 sample_rate = MCP3422_SAMPLE_RATE(config);
208 u8 i;
209
210 switch (mask) {
211 case IIO_CHAN_INFO_SCALE:
212 if (val1 != 0)
213 return -EINVAL;
214
215 for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
216 if (val2 == mcp3422_scales[sample_rate][i]) {
217 adc->pga[req_channel] = i;
218
219 config &= ~MCP3422_CHANNEL_MASK;
220 config |= MCP3422_CHANNEL_VALUE(req_channel);
221 config &= ~MCP3422_PGA_MASK;
222 config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
223
224 return mcp3422_update_config(adc, config);
225 }
226 }
227 return -EINVAL;
228
229 case IIO_CHAN_INFO_SAMP_FREQ:
230 switch (val1) {
231 case 240:
232 temp = MCP3422_SRATE_240;
233 break;
234 case 60:
235 temp = MCP3422_SRATE_60;
236 break;
237 case 15:
238 temp = MCP3422_SRATE_15;
239 break;
240 case 3:
241 temp = MCP3422_SRATE_3;
242 break;
243 default:
244 return -EINVAL;
245 }
246
247 config &= ~MCP3422_CHANNEL_MASK;
248 config |= MCP3422_CHANNEL_VALUE(req_channel);
249 config &= ~MCP3422_SRATE_MASK;
250 config |= MCP3422_SAMPLE_RATE_VALUE(temp);
251
252 return mcp3422_update_config(adc, config);
253
254 default:
255 break;
256 }
257
258 return -EINVAL;
259}
260
261static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
262 struct iio_chan_spec const *chan, long mask)
263{
264 switch (mask) {
265 case IIO_CHAN_INFO_SCALE:
266 return IIO_VAL_INT_PLUS_NANO;
267 case IIO_CHAN_INFO_SAMP_FREQ:
268 return IIO_VAL_INT_PLUS_MICRO;
269 default:
270 return -EINVAL;
271 }
272}
273
274static ssize_t mcp3422_show_scales(struct device *dev,
275 struct device_attribute *attr, char *buf)
276{
277 struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
278 u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
279
280 return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
281 mcp3422_scales[sample_rate][0],
282 mcp3422_scales[sample_rate][1],
283 mcp3422_scales[sample_rate][2],
284 mcp3422_scales[sample_rate][3]);
285}
286
287static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3");
288static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
289 mcp3422_show_scales, NULL, 0);
290
291static struct attribute *mcp3422_attributes[] = {
292 &iio_const_attr_sampling_frequency_available.dev_attr.attr,
293 &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
294 NULL,
295};
296
297static const struct attribute_group mcp3422_attribute_group = {
298 .attrs = mcp3422_attributes,
299};
300
301static const struct iio_chan_spec mcp3422_channels[] = {
302 MCP3422_CHAN(0),
303 MCP3422_CHAN(1),
304};
305
306static const struct iio_chan_spec mcp3424_channels[] = {
307 MCP3422_CHAN(0),
308 MCP3422_CHAN(1),
309 MCP3422_CHAN(2),
310 MCP3422_CHAN(3),
311};
312
313static const struct iio_info mcp3422_info = {
314 .read_raw = mcp3422_read_raw,
315 .write_raw = mcp3422_write_raw,
316 .write_raw_get_fmt = mcp3422_write_raw_get_fmt,
317 .attrs = &mcp3422_attribute_group,
318 .driver_module = THIS_MODULE,
319};
320
321static int mcp3422_probe(struct i2c_client *client,
322 const struct i2c_device_id *id)
323{
324 struct iio_dev *indio_dev;
325 struct mcp3422 *adc;
326 int err;
327 u8 config;
328
329 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
330 return -ENODEV;
331
332 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
333 if (!indio_dev)
334 return -ENOMEM;
335
336 adc = iio_priv(indio_dev);
337 adc->i2c = client;
338
339 mutex_init(&adc->lock);
340
341 indio_dev->dev.parent = &client->dev;
342 indio_dev->name = dev_name(&client->dev);
343 indio_dev->modes = INDIO_DIRECT_MODE;
344 indio_dev->info = &mcp3422_info;
345
346 switch ((unsigned int)(id->driver_data)) {
347 case 2:
348 case 3:
349 indio_dev->channels = mcp3422_channels;
350 indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
351 break;
352 case 4:
353 indio_dev->channels = mcp3424_channels;
354 indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
355 break;
356 }
357
358 /* meaningful default configuration */
359 config = (MCP3422_CONT_SAMPLING
360 | MCP3422_CHANNEL_VALUE(1)
361 | MCP3422_PGA_VALUE(MCP3422_PGA_1)
362 | MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
363 mcp3422_update_config(adc, config);
364
365 err = iio_device_register(indio_dev);
366 if (err < 0)
367 return err;
368
369 i2c_set_clientdata(client, indio_dev);
370
371 return 0;
372}
373
374static int mcp3422_remove(struct i2c_client *client)
375{
376 iio_device_unregister(i2c_get_clientdata(client));
377 return 0;
378}
379
380static const struct i2c_device_id mcp3422_id[] = {
381 { "mcp3422", 2 },
382 { "mcp3423", 3 },
383 { "mcp3424", 4 },
384 { }
385};
386MODULE_DEVICE_TABLE(i2c, mcp3422_id);
387
388#ifdef CONFIG_OF
389static const struct of_device_id mcp3422_of_match[] = {
390 { .compatible = "mcp3422" },
391 { }
392};
393MODULE_DEVICE_TABLE(of, mcp3422_of_match);
394#endif
395
396static struct i2c_driver mcp3422_driver = {
397 .driver = {
398 .name = "mcp3422",
399 .owner = THIS_MODULE,
400 .of_match_table = of_match_ptr(mcp3422_of_match),
401 },
402 .probe = mcp3422_probe,
403 .remove = mcp3422_remove,
404 .id_table = mcp3422_id,
405};
406module_i2c_driver(mcp3422_driver);
407
408MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
409MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
410MODULE_LICENSE("GPL v2");