xref: /openbmc/linux/drivers/iio/adc/mcp320x.c (revision 9cfc5c90) 
1 /*
2  * Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
3  * Copyright (C) 2014 Rose Technology
4  * 	   Allan Bendorff Jensen <abj@rosetechnology.dk>
5  *	   Soren Andersen <san@rosetechnology.dk>
6  *
7  * Driver for following ADC chips from Microchip Technology's:
8  * 10 Bit converter
9  * MCP3001
10  * MCP3002
11  * MCP3004
12  * MCP3008
13  * ------------
14  * 12 bit converter
15  * MCP3201
16  * MCP3202
17  * MCP3204
18  * MCP3208
19  * ------------
20  *
21  * Datasheet can be found here:
22  * http://ww1.microchip.com/downloads/en/DeviceDoc/21293C.pdf  mcp3001
23  * http://ww1.microchip.com/downloads/en/DeviceDoc/21294E.pdf  mcp3002
24  * http://ww1.microchip.com/downloads/en/DeviceDoc/21295d.pdf  mcp3004/08
25  * http://ww1.microchip.com/downloads/en/DeviceDoc/21290D.pdf  mcp3201
26  * http://ww1.microchip.com/downloads/en/DeviceDoc/21034D.pdf  mcp3202
27  * http://ww1.microchip.com/downloads/en/DeviceDoc/21298c.pdf  mcp3204/08
28  * http://ww1.microchip.com/downloads/en/DeviceDoc/21700E.pdf  mcp3301
29  *
30  * This program is free software; you can redistribute it and/or modify
31  * it under the terms of the GNU General Public License version 2 as
32  * published by the Free Software Foundation.
33  */
34 
35 #include <linux/err.h>
36 #include <linux/delay.h>
37 #include <linux/spi/spi.h>
38 #include <linux/module.h>
39 #include <linux/iio/iio.h>
40 #include <linux/regulator/consumer.h>
41 
42 enum {
43 	mcp3001,
44 	mcp3002,
45 	mcp3004,
46 	mcp3008,
47 	mcp3201,
48 	mcp3202,
49 	mcp3204,
50 	mcp3208,
51 	mcp3301,
52 };
53 
54 struct mcp320x_chip_info {
55 	const struct iio_chan_spec *channels;
56 	unsigned int num_channels;
57 	unsigned int resolution;
58 };
59 
60 struct mcp320x {
61 	struct spi_device *spi;
62 	struct spi_message msg;
63 	struct spi_transfer transfer[2];
64 
65 	struct regulator *reg;
66 	struct mutex lock;
67 	const struct mcp320x_chip_info *chip_info;
68 
69 	u8 tx_buf ____cacheline_aligned;
70 	u8 rx_buf[2];
71 };
72 
73 static int mcp320x_channel_to_tx_data(int device_index,
74 			const unsigned int channel, bool differential)
75 {
76 	int start_bit = 1;
77 
78 	switch (device_index) {
79 	case mcp3001:
80 	case mcp3201:
81 	case mcp3301:
82 		return 0;
83 	case mcp3002:
84 	case mcp3202:
85 		return ((start_bit << 4) | (!differential << 3) |
86 							(channel << 2));
87 	case mcp3004:
88 	case mcp3204:
89 	case mcp3008:
90 	case mcp3208:
91 		return ((start_bit << 6) | (!differential << 5) |
92 							(channel << 2));
93 	default:
94 		return -EINVAL;
95 	}
96 }
97 
98 static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
99 				  bool differential, int device_index)
100 {
101 	int ret;
102 
103 	adc->rx_buf[0] = 0;
104 	adc->rx_buf[1] = 0;
105 	adc->tx_buf = mcp320x_channel_to_tx_data(device_index,
106 						channel, differential);
107 
108 	if (device_index != mcp3001 && device_index != mcp3201 && device_index != mcp3301) {
109 		ret = spi_sync(adc->spi, &adc->msg);
110 		if (ret < 0)
111 			return ret;
112 	} else {
113 		ret = spi_read(adc->spi, &adc->rx_buf, sizeof(adc->rx_buf));
114 		if (ret < 0)
115 			return ret;
116 	}
117 
118 	switch (device_index) {
119 	case mcp3001:
120 		return (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3);
121 	case mcp3002:
122 	case mcp3004:
123 	case mcp3008:
124 		return (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6);
125 	case mcp3201:
126 		return (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1);
127 	case mcp3202:
128 	case mcp3204:
129 	case mcp3208:
130 		return (adc->rx_buf[0] << 4 | adc->rx_buf[1] >> 4);
131 	case mcp3301:
132 		return sign_extend32((adc->rx_buf[0] & 0x1f) << 8 | adc->rx_buf[1], 12);
133 	default:
134 		return -EINVAL;
135 	}
136 }
137 
138 static int mcp320x_read_raw(struct iio_dev *indio_dev,
139 			    struct iio_chan_spec const *channel, int *val,
140 			    int *val2, long mask)
141 {
142 	struct mcp320x *adc = iio_priv(indio_dev);
143 	int ret = -EINVAL;
144 	int device_index = 0;
145 
146 	mutex_lock(&adc->lock);
147 
148 	device_index = spi_get_device_id(adc->spi)->driver_data;
149 
150 	switch (mask) {
151 	case IIO_CHAN_INFO_RAW:
152 		ret = mcp320x_adc_conversion(adc, channel->address,
153 			channel->differential, device_index);
154 
155 		if (ret < 0)
156 			goto out;
157 
158 		*val = ret;
159 		ret = IIO_VAL_INT;
160 		break;
161 
162 	case IIO_CHAN_INFO_SCALE:
163 		ret = regulator_get_voltage(adc->reg);
164 		if (ret < 0)
165 			goto out;
166 
167 		/* convert regulator output voltage to mV */
168 		*val = ret / 1000;
169 		*val2 = adc->chip_info->resolution;
170 		ret = IIO_VAL_FRACTIONAL_LOG2;
171 		break;
172 	}
173 
174 out:
175 	mutex_unlock(&adc->lock);
176 
177 	return ret;
178 }
179 
180 #define MCP320X_VOLTAGE_CHANNEL(num)				\
181 	{							\
182 		.type = IIO_VOLTAGE,				\
183 		.indexed = 1,					\
184 		.channel = (num),				\
185 		.address = (num),				\
186 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
187 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
188 	}
189 
190 #define MCP320X_VOLTAGE_CHANNEL_DIFF(num)			\
191 	{							\
192 		.type = IIO_VOLTAGE,				\
193 		.indexed = 1,					\
194 		.channel = (num * 2),				\
195 		.channel2 = (num * 2 + 1),			\
196 		.address = (num * 2),				\
197 		.differential = 1,				\
198 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
199 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
200 	}
201 
202 static const struct iio_chan_spec mcp3201_channels[] = {
203 	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
204 };
205 
206 static const struct iio_chan_spec mcp3202_channels[] = {
207 	MCP320X_VOLTAGE_CHANNEL(0),
208 	MCP320X_VOLTAGE_CHANNEL(1),
209 	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
210 };
211 
212 static const struct iio_chan_spec mcp3204_channels[] = {
213 	MCP320X_VOLTAGE_CHANNEL(0),
214 	MCP320X_VOLTAGE_CHANNEL(1),
215 	MCP320X_VOLTAGE_CHANNEL(2),
216 	MCP320X_VOLTAGE_CHANNEL(3),
217 	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
218 	MCP320X_VOLTAGE_CHANNEL_DIFF(1),
219 };
220 
221 static const struct iio_chan_spec mcp3208_channels[] = {
222 	MCP320X_VOLTAGE_CHANNEL(0),
223 	MCP320X_VOLTAGE_CHANNEL(1),
224 	MCP320X_VOLTAGE_CHANNEL(2),
225 	MCP320X_VOLTAGE_CHANNEL(3),
226 	MCP320X_VOLTAGE_CHANNEL(4),
227 	MCP320X_VOLTAGE_CHANNEL(5),
228 	MCP320X_VOLTAGE_CHANNEL(6),
229 	MCP320X_VOLTAGE_CHANNEL(7),
230 	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
231 	MCP320X_VOLTAGE_CHANNEL_DIFF(1),
232 	MCP320X_VOLTAGE_CHANNEL_DIFF(2),
233 	MCP320X_VOLTAGE_CHANNEL_DIFF(3),
234 };
235 
236 static const struct iio_info mcp320x_info = {
237 	.read_raw = mcp320x_read_raw,
238 	.driver_module = THIS_MODULE,
239 };
240 
241 static const struct mcp320x_chip_info mcp320x_chip_infos[] = {
242 	[mcp3001] = {
243 		.channels = mcp3201_channels,
244 		.num_channels = ARRAY_SIZE(mcp3201_channels),
245 		.resolution = 10
246 	},
247 	[mcp3002] = {
248 		.channels = mcp3202_channels,
249 		.num_channels = ARRAY_SIZE(mcp3202_channels),
250 		.resolution = 10
251 	},
252 	[mcp3004] = {
253 		.channels = mcp3204_channels,
254 		.num_channels = ARRAY_SIZE(mcp3204_channels),
255 		.resolution = 10
256 	},
257 	[mcp3008] = {
258 		.channels = mcp3208_channels,
259 		.num_channels = ARRAY_SIZE(mcp3208_channels),
260 		.resolution = 10
261 	},
262 	[mcp3201] = {
263 		.channels = mcp3201_channels,
264 		.num_channels = ARRAY_SIZE(mcp3201_channels),
265 		.resolution = 12
266 	},
267 	[mcp3202] = {
268 		.channels = mcp3202_channels,
269 		.num_channels = ARRAY_SIZE(mcp3202_channels),
270 		.resolution = 12
271 	},
272 	[mcp3204] = {
273 		.channels = mcp3204_channels,
274 		.num_channels = ARRAY_SIZE(mcp3204_channels),
275 		.resolution = 12
276 	},
277 	[mcp3208] = {
278 		.channels = mcp3208_channels,
279 		.num_channels = ARRAY_SIZE(mcp3208_channels),
280 		.resolution = 12
281 	},
282 	[mcp3301] = {
283 		.channels = mcp3201_channels,
284 		.num_channels = ARRAY_SIZE(mcp3201_channels),
285 		.resolution = 13
286 	},
287 };
288 
289 static int mcp320x_probe(struct spi_device *spi)
290 {
291 	struct iio_dev *indio_dev;
292 	struct mcp320x *adc;
293 	const struct mcp320x_chip_info *chip_info;
294 	int ret;
295 
296 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
297 	if (!indio_dev)
298 		return -ENOMEM;
299 
300 	adc = iio_priv(indio_dev);
301 	adc->spi = spi;
302 
303 	indio_dev->dev.parent = &spi->dev;
304 	indio_dev->name = spi_get_device_id(spi)->name;
305 	indio_dev->modes = INDIO_DIRECT_MODE;
306 	indio_dev->info = &mcp320x_info;
307 
308 	chip_info = &mcp320x_chip_infos[spi_get_device_id(spi)->driver_data];
309 	indio_dev->channels = chip_info->channels;
310 	indio_dev->num_channels = chip_info->num_channels;
311 
312 	adc->chip_info = chip_info;
313 
314 	adc->transfer[0].tx_buf = &adc->tx_buf;
315 	adc->transfer[0].len = sizeof(adc->tx_buf);
316 	adc->transfer[1].rx_buf = adc->rx_buf;
317 	adc->transfer[1].len = sizeof(adc->rx_buf);
318 
319 	spi_message_init_with_transfers(&adc->msg, adc->transfer,
320 					ARRAY_SIZE(adc->transfer));
321 
322 	adc->reg = devm_regulator_get(&spi->dev, "vref");
323 	if (IS_ERR(adc->reg))
324 		return PTR_ERR(adc->reg);
325 
326 	ret = regulator_enable(adc->reg);
327 	if (ret < 0)
328 		return ret;
329 
330 	mutex_init(&adc->lock);
331 
332 	ret = iio_device_register(indio_dev);
333 	if (ret < 0)
334 		goto reg_disable;
335 
336 	return 0;
337 
338 reg_disable:
339 	regulator_disable(adc->reg);
340 
341 	return ret;
342 }
343 
344 static int mcp320x_remove(struct spi_device *spi)
345 {
346 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
347 	struct mcp320x *adc = iio_priv(indio_dev);
348 
349 	iio_device_unregister(indio_dev);
350 	regulator_disable(adc->reg);
351 
352 	return 0;
353 }
354 
355 #if defined(CONFIG_OF)
356 static const struct of_device_id mcp320x_dt_ids[] = {
357 	{
358 		.compatible = "mcp3001",
359 		.data = &mcp320x_chip_infos[mcp3001],
360 	}, {
361 		.compatible = "mcp3002",
362 		.data = &mcp320x_chip_infos[mcp3002],
363 	}, {
364 		.compatible = "mcp3004",
365 		.data = &mcp320x_chip_infos[mcp3004],
366 	}, {
367 		.compatible = "mcp3008",
368 		.data = &mcp320x_chip_infos[mcp3008],
369 	}, {
370 		.compatible = "mcp3201",
371 		.data = &mcp320x_chip_infos[mcp3201],
372 	}, {
373 		.compatible = "mcp3202",
374 		.data = &mcp320x_chip_infos[mcp3202],
375 	}, {
376 		.compatible = "mcp3204",
377 		.data = &mcp320x_chip_infos[mcp3204],
378 	}, {
379 		.compatible = "mcp3208",
380 		.data = &mcp320x_chip_infos[mcp3208],
381 	}, {
382 		.compatible = "mcp3301",
383 		.data = &mcp320x_chip_infos[mcp3301],
384 	}, {
385 	}
386 };
387 MODULE_DEVICE_TABLE(of, mcp320x_dt_ids);
388 #endif
389 
390 static const struct spi_device_id mcp320x_id[] = {
391 	{ "mcp3001", mcp3001 },
392 	{ "mcp3002", mcp3002 },
393 	{ "mcp3004", mcp3004 },
394 	{ "mcp3008", mcp3008 },
395 	{ "mcp3201", mcp3201 },
396 	{ "mcp3202", mcp3202 },
397 	{ "mcp3204", mcp3204 },
398 	{ "mcp3208", mcp3208 },
399 	{ "mcp3301", mcp3301 },
400 	{ }
401 };
402 MODULE_DEVICE_TABLE(spi, mcp320x_id);
403 
404 static struct spi_driver mcp320x_driver = {
405 	.driver = {
406 		.name = "mcp320x",
407 		.of_match_table = of_match_ptr(mcp320x_dt_ids),
408 	},
409 	.probe = mcp320x_probe,
410 	.remove = mcp320x_remove,
411 	.id_table = mcp320x_id,
412 };
413 module_spi_driver(mcp320x_driver);
414 
415 MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>");
416 MODULE_DESCRIPTION("Microchip Technology MCP3x01/02/04/08");
417 MODULE_LICENSE("GPL v2");
418