xref: /openbmc/linux/drivers/iio/adc/mcp3422.c (revision 79f08d9e)
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 */
61 static 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 
69 static 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 */
76 static 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 */
83 static 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 */
90 static const int mcp3422_sign_extend[4] = {
91 	[MCP3422_SRATE_240] = 12,
92 	[MCP3422_SRATE_60] = 14,
93 	[MCP3422_SRATE_15] = 16,
94 	[MCP3422_SRATE_3] = 18 };
95 
96 /* Client data (each client gets its own) */
97 struct mcp3422 {
98 	struct i2c_client *i2c;
99 	u8 config;
100 	u8 pga[4];
101 	struct mutex lock;
102 };
103 
104 static 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 
121 static 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 
143 static 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 
165 static 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 
199 static 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 
261 static 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 
274 static 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 
287 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3");
288 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
289 		mcp3422_show_scales, NULL, 0);
290 
291 static 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 
297 static const struct attribute_group mcp3422_attribute_group = {
298 	.attrs = mcp3422_attributes,
299 };
300 
301 static const struct iio_chan_spec mcp3422_channels[] = {
302 	MCP3422_CHAN(0),
303 	MCP3422_CHAN(1),
304 };
305 
306 static 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 
313 static 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 
321 static 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 
374 static int mcp3422_remove(struct i2c_client *client)
375 {
376 	iio_device_unregister(i2c_get_clientdata(client));
377 	return 0;
378 }
379 
380 static const struct i2c_device_id mcp3422_id[] = {
381 	{ "mcp3422", 2 },
382 	{ "mcp3423", 3 },
383 	{ "mcp3424", 4 },
384 	{ }
385 };
386 MODULE_DEVICE_TABLE(i2c, mcp3422_id);
387 
388 #ifdef CONFIG_OF
389 static const struct of_device_id mcp3422_of_match[] = {
390 	{ .compatible = "mcp3422" },
391 	{ }
392 };
393 MODULE_DEVICE_TABLE(of, mcp3422_of_match);
394 #endif
395 
396 static 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 };
406 module_i2c_driver(mcp3422_driver);
407 
408 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
409 MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
410 MODULE_LICENSE("GPL v2");
411