1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Industrial I/O driver for Microchip digital potentiometers
4  *
5  * Copyright (c) 2016 Slawomir Stepien
6  * Based on: Peter Rosin's code from mcp4531.c
7  *
8  * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf
9  *
10  * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)
11  * mcp4131	1	129		5, 10, 50, 100
12  * mcp4132	1	129		5, 10, 50, 100
13  * mcp4141	1	129		5, 10, 50, 100
14  * mcp4142	1	129		5, 10, 50, 100
15  * mcp4151	1	257		5, 10, 50, 100
16  * mcp4152	1	257		5, 10, 50, 100
17  * mcp4161	1	257		5, 10, 50, 100
18  * mcp4162	1	257		5, 10, 50, 100
19  * mcp4231	2	129		5, 10, 50, 100
20  * mcp4232	2	129		5, 10, 50, 100
21  * mcp4241	2	129		5, 10, 50, 100
22  * mcp4242	2	129		5, 10, 50, 100
23  * mcp4251	2	257		5, 10, 50, 100
24  * mcp4252	2	257		5, 10, 50, 100
25  * mcp4261	2	257		5, 10, 50, 100
26  * mcp4262	2	257		5, 10, 50, 100
27  */
28 
29 /*
30  * TODO:
31  * 1. Write wiper setting to EEPROM for EEPROM capable models.
32  */
33 
34 #include <linux/cache.h>
35 #include <linux/err.h>
36 #include <linux/export.h>
37 #include <linux/iio/iio.h>
38 #include <linux/iio/types.h>
39 #include <linux/module.h>
40 #include <linux/mod_devicetable.h>
41 #include <linux/mutex.h>
42 #include <linux/property.h>
43 #include <linux/spi/spi.h>
44 
45 #define MCP4131_WRITE		(0x00 << 2)
46 #define MCP4131_READ		(0x03 << 2)
47 
48 #define MCP4131_WIPER_SHIFT	4
49 #define MCP4131_CMDERR(r)	((r[0]) & 0x02)
50 #define MCP4131_RAW(r)		((r[0]) == 0xff ? 0x100 : (r[1]))
51 
52 struct mcp4131_cfg {
53 	int wipers;
54 	int max_pos;
55 	int kohms;
56 };
57 
58 enum mcp4131_type {
59 	MCP413x_502 = 0,
60 	MCP413x_103,
61 	MCP413x_503,
62 	MCP413x_104,
63 	MCP414x_502,
64 	MCP414x_103,
65 	MCP414x_503,
66 	MCP414x_104,
67 	MCP415x_502,
68 	MCP415x_103,
69 	MCP415x_503,
70 	MCP415x_104,
71 	MCP416x_502,
72 	MCP416x_103,
73 	MCP416x_503,
74 	MCP416x_104,
75 	MCP423x_502,
76 	MCP423x_103,
77 	MCP423x_503,
78 	MCP423x_104,
79 	MCP424x_502,
80 	MCP424x_103,
81 	MCP424x_503,
82 	MCP424x_104,
83 	MCP425x_502,
84 	MCP425x_103,
85 	MCP425x_503,
86 	MCP425x_104,
87 	MCP426x_502,
88 	MCP426x_103,
89 	MCP426x_503,
90 	MCP426x_104,
91 };
92 
93 static const struct mcp4131_cfg mcp4131_cfg[] = {
94 	[MCP413x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
95 	[MCP413x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
96 	[MCP413x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
97 	[MCP413x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
98 	[MCP414x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
99 	[MCP414x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
100 	[MCP414x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
101 	[MCP414x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
102 	[MCP415x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
103 	[MCP415x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
104 	[MCP415x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
105 	[MCP415x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
106 	[MCP416x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
107 	[MCP416x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
108 	[MCP416x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
109 	[MCP416x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
110 	[MCP423x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
111 	[MCP423x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
112 	[MCP423x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
113 	[MCP423x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
114 	[MCP424x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
115 	[MCP424x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
116 	[MCP424x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
117 	[MCP424x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
118 	[MCP425x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
119 	[MCP425x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
120 	[MCP425x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
121 	[MCP425x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
122 	[MCP426x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
123 	[MCP426x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
124 	[MCP426x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
125 	[MCP426x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
126 };
127 
128 struct mcp4131_data {
129 	struct spi_device *spi;
130 	const struct mcp4131_cfg *cfg;
131 	struct mutex lock;
132 	u8 buf[2] __aligned(IIO_DMA_MINALIGN);
133 };
134 
135 #define MCP4131_CHANNEL(ch) {					\
136 	.type = IIO_RESISTANCE,					\
137 	.indexed = 1,						\
138 	.output = 1,						\
139 	.channel = (ch),					\
140 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
141 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
142 }
143 
144 static const struct iio_chan_spec mcp4131_channels[] = {
145 	MCP4131_CHANNEL(0),
146 	MCP4131_CHANNEL(1),
147 };
148 
149 static int mcp4131_read(struct spi_device *spi, void *buf, size_t len)
150 {
151 	struct spi_transfer t = {
152 		.tx_buf = buf, /* We need to send addr, cmd and 12 bits */
153 		.rx_buf	= buf,
154 		.len = len,
155 	};
156 	struct spi_message m;
157 
158 	spi_message_init(&m);
159 	spi_message_add_tail(&t, &m);
160 
161 	return spi_sync(spi, &m);
162 }
163 
164 static int mcp4131_read_raw(struct iio_dev *indio_dev,
165 			    struct iio_chan_spec const *chan,
166 			    int *val, int *val2, long mask)
167 {
168 	int err;
169 	struct mcp4131_data *data = iio_priv(indio_dev);
170 	int address = chan->channel;
171 
172 	switch (mask) {
173 	case IIO_CHAN_INFO_RAW:
174 		mutex_lock(&data->lock);
175 
176 		data->buf[0] = (address << MCP4131_WIPER_SHIFT) | MCP4131_READ;
177 		data->buf[1] = 0;
178 
179 		err = mcp4131_read(data->spi, data->buf, 2);
180 		if (err) {
181 			mutex_unlock(&data->lock);
182 			return err;
183 		}
184 
185 		/* Error, bad address/command combination */
186 		if (!MCP4131_CMDERR(data->buf)) {
187 			mutex_unlock(&data->lock);
188 			return -EIO;
189 		}
190 
191 		*val = MCP4131_RAW(data->buf);
192 		mutex_unlock(&data->lock);
193 
194 		return IIO_VAL_INT;
195 
196 	case IIO_CHAN_INFO_SCALE:
197 		*val = 1000 * data->cfg->kohms;
198 		*val2 = data->cfg->max_pos;
199 		return IIO_VAL_FRACTIONAL;
200 	}
201 
202 	return -EINVAL;
203 }
204 
205 static int mcp4131_write_raw(struct iio_dev *indio_dev,
206 			     struct iio_chan_spec const *chan,
207 			     int val, int val2, long mask)
208 {
209 	int err;
210 	struct mcp4131_data *data = iio_priv(indio_dev);
211 	int address = chan->channel << MCP4131_WIPER_SHIFT;
212 
213 	switch (mask) {
214 	case IIO_CHAN_INFO_RAW:
215 		if (val > data->cfg->max_pos || val < 0)
216 			return -EINVAL;
217 		break;
218 
219 	default:
220 		return -EINVAL;
221 	}
222 
223 	mutex_lock(&data->lock);
224 
225 	data->buf[0] = address << MCP4131_WIPER_SHIFT;
226 	data->buf[0] |= MCP4131_WRITE | (val >> 8);
227 	data->buf[1] = val & 0xFF; /* 8 bits here */
228 
229 	err = spi_write(data->spi, data->buf, 2);
230 	mutex_unlock(&data->lock);
231 
232 	return err;
233 }
234 
235 static const struct iio_info mcp4131_info = {
236 	.read_raw = mcp4131_read_raw,
237 	.write_raw = mcp4131_write_raw,
238 };
239 
240 static int mcp4131_probe(struct spi_device *spi)
241 {
242 	int err;
243 	struct device *dev = &spi->dev;
244 	unsigned long devid;
245 	struct mcp4131_data *data;
246 	struct iio_dev *indio_dev;
247 
248 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
249 	if (!indio_dev)
250 		return -ENOMEM;
251 
252 	data = iio_priv(indio_dev);
253 	spi_set_drvdata(spi, indio_dev);
254 	data->spi = spi;
255 	data->cfg = device_get_match_data(&spi->dev);
256 	if (!data->cfg) {
257 		devid = spi_get_device_id(spi)->driver_data;
258 		data->cfg = &mcp4131_cfg[devid];
259 	}
260 
261 	mutex_init(&data->lock);
262 
263 	indio_dev->info = &mcp4131_info;
264 	indio_dev->channels = mcp4131_channels;
265 	indio_dev->num_channels = data->cfg->wipers;
266 	indio_dev->name = spi_get_device_id(spi)->name;
267 
268 	err = devm_iio_device_register(dev, indio_dev);
269 	if (err) {
270 		dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
271 		return err;
272 	}
273 
274 	return 0;
275 }
276 
277 static const struct of_device_id mcp4131_dt_ids[] = {
278 	{ .compatible = "microchip,mcp4131-502",
279 		.data = &mcp4131_cfg[MCP413x_502] },
280 	{ .compatible = "microchip,mcp4131-103",
281 		.data = &mcp4131_cfg[MCP413x_103] },
282 	{ .compatible = "microchip,mcp4131-503",
283 		.data = &mcp4131_cfg[MCP413x_503] },
284 	{ .compatible = "microchip,mcp4131-104",
285 		.data = &mcp4131_cfg[MCP413x_104] },
286 	{ .compatible = "microchip,mcp4132-502",
287 		.data = &mcp4131_cfg[MCP413x_502] },
288 	{ .compatible = "microchip,mcp4132-103",
289 		.data = &mcp4131_cfg[MCP413x_103] },
290 	{ .compatible = "microchip,mcp4132-503",
291 		.data = &mcp4131_cfg[MCP413x_503] },
292 	{ .compatible = "microchip,mcp4132-104",
293 		.data = &mcp4131_cfg[MCP413x_104] },
294 	{ .compatible = "microchip,mcp4141-502",
295 		.data = &mcp4131_cfg[MCP414x_502] },
296 	{ .compatible = "microchip,mcp4141-103",
297 		.data = &mcp4131_cfg[MCP414x_103] },
298 	{ .compatible = "microchip,mcp4141-503",
299 		.data = &mcp4131_cfg[MCP414x_503] },
300 	{ .compatible = "microchip,mcp4141-104",
301 		.data = &mcp4131_cfg[MCP414x_104] },
302 	{ .compatible = "microchip,mcp4142-502",
303 		.data = &mcp4131_cfg[MCP414x_502] },
304 	{ .compatible = "microchip,mcp4142-103",
305 		.data = &mcp4131_cfg[MCP414x_103] },
306 	{ .compatible = "microchip,mcp4142-503",
307 		.data = &mcp4131_cfg[MCP414x_503] },
308 	{ .compatible = "microchip,mcp4142-104",
309 		.data = &mcp4131_cfg[MCP414x_104] },
310 	{ .compatible = "microchip,mcp4151-502",
311 		.data = &mcp4131_cfg[MCP415x_502] },
312 	{ .compatible = "microchip,mcp4151-103",
313 		.data = &mcp4131_cfg[MCP415x_103] },
314 	{ .compatible = "microchip,mcp4151-503",
315 		.data = &mcp4131_cfg[MCP415x_503] },
316 	{ .compatible = "microchip,mcp4151-104",
317 		.data = &mcp4131_cfg[MCP415x_104] },
318 	{ .compatible = "microchip,mcp4152-502",
319 		.data = &mcp4131_cfg[MCP415x_502] },
320 	{ .compatible = "microchip,mcp4152-103",
321 		.data = &mcp4131_cfg[MCP415x_103] },
322 	{ .compatible = "microchip,mcp4152-503",
323 		.data = &mcp4131_cfg[MCP415x_503] },
324 	{ .compatible = "microchip,mcp4152-104",
325 		.data = &mcp4131_cfg[MCP415x_104] },
326 	{ .compatible = "microchip,mcp4161-502",
327 		.data = &mcp4131_cfg[MCP416x_502] },
328 	{ .compatible = "microchip,mcp4161-103",
329 		.data = &mcp4131_cfg[MCP416x_103] },
330 	{ .compatible = "microchip,mcp4161-503",
331 		.data = &mcp4131_cfg[MCP416x_503] },
332 	{ .compatible = "microchip,mcp4161-104",
333 		.data = &mcp4131_cfg[MCP416x_104] },
334 	{ .compatible = "microchip,mcp4162-502",
335 		.data = &mcp4131_cfg[MCP416x_502] },
336 	{ .compatible = "microchip,mcp4162-103",
337 		.data = &mcp4131_cfg[MCP416x_103] },
338 	{ .compatible = "microchip,mcp4162-503",
339 		.data = &mcp4131_cfg[MCP416x_503] },
340 	{ .compatible = "microchip,mcp4162-104",
341 		.data = &mcp4131_cfg[MCP416x_104] },
342 	{ .compatible = "microchip,mcp4231-502",
343 		.data = &mcp4131_cfg[MCP423x_502] },
344 	{ .compatible = "microchip,mcp4231-103",
345 		.data = &mcp4131_cfg[MCP423x_103] },
346 	{ .compatible = "microchip,mcp4231-503",
347 		.data = &mcp4131_cfg[MCP423x_503] },
348 	{ .compatible = "microchip,mcp4231-104",
349 		.data = &mcp4131_cfg[MCP423x_104] },
350 	{ .compatible = "microchip,mcp4232-502",
351 		.data = &mcp4131_cfg[MCP423x_502] },
352 	{ .compatible = "microchip,mcp4232-103",
353 		.data = &mcp4131_cfg[MCP423x_103] },
354 	{ .compatible = "microchip,mcp4232-503",
355 		.data = &mcp4131_cfg[MCP423x_503] },
356 	{ .compatible = "microchip,mcp4232-104",
357 		.data = &mcp4131_cfg[MCP423x_104] },
358 	{ .compatible = "microchip,mcp4241-502",
359 		.data = &mcp4131_cfg[MCP424x_502] },
360 	{ .compatible = "microchip,mcp4241-103",
361 		.data = &mcp4131_cfg[MCP424x_103] },
362 	{ .compatible = "microchip,mcp4241-503",
363 		.data = &mcp4131_cfg[MCP424x_503] },
364 	{ .compatible = "microchip,mcp4241-104",
365 		.data = &mcp4131_cfg[MCP424x_104] },
366 	{ .compatible = "microchip,mcp4242-502",
367 		.data = &mcp4131_cfg[MCP424x_502] },
368 	{ .compatible = "microchip,mcp4242-103",
369 		.data = &mcp4131_cfg[MCP424x_103] },
370 	{ .compatible = "microchip,mcp4242-503",
371 		.data = &mcp4131_cfg[MCP424x_503] },
372 	{ .compatible = "microchip,mcp4242-104",
373 		.data = &mcp4131_cfg[MCP424x_104] },
374 	{ .compatible = "microchip,mcp4251-502",
375 		.data = &mcp4131_cfg[MCP425x_502] },
376 	{ .compatible = "microchip,mcp4251-103",
377 		.data = &mcp4131_cfg[MCP425x_103] },
378 	{ .compatible = "microchip,mcp4251-503",
379 		.data = &mcp4131_cfg[MCP425x_503] },
380 	{ .compatible = "microchip,mcp4251-104",
381 		.data = &mcp4131_cfg[MCP425x_104] },
382 	{ .compatible = "microchip,mcp4252-502",
383 		.data = &mcp4131_cfg[MCP425x_502] },
384 	{ .compatible = "microchip,mcp4252-103",
385 		.data = &mcp4131_cfg[MCP425x_103] },
386 	{ .compatible = "microchip,mcp4252-503",
387 		.data = &mcp4131_cfg[MCP425x_503] },
388 	{ .compatible = "microchip,mcp4252-104",
389 		.data = &mcp4131_cfg[MCP425x_104] },
390 	{ .compatible = "microchip,mcp4261-502",
391 		.data = &mcp4131_cfg[MCP426x_502] },
392 	{ .compatible = "microchip,mcp4261-103",
393 		.data = &mcp4131_cfg[MCP426x_103] },
394 	{ .compatible = "microchip,mcp4261-503",
395 		.data = &mcp4131_cfg[MCP426x_503] },
396 	{ .compatible = "microchip,mcp4261-104",
397 		.data = &mcp4131_cfg[MCP426x_104] },
398 	{ .compatible = "microchip,mcp4262-502",
399 		.data = &mcp4131_cfg[MCP426x_502] },
400 	{ .compatible = "microchip,mcp4262-103",
401 		.data = &mcp4131_cfg[MCP426x_103] },
402 	{ .compatible = "microchip,mcp4262-503",
403 		.data = &mcp4131_cfg[MCP426x_503] },
404 	{ .compatible = "microchip,mcp4262-104",
405 		.data = &mcp4131_cfg[MCP426x_104] },
406 	{}
407 };
408 MODULE_DEVICE_TABLE(of, mcp4131_dt_ids);
409 
410 static const struct spi_device_id mcp4131_id[] = {
411 	{ "mcp4131-502", MCP413x_502 },
412 	{ "mcp4131-103", MCP413x_103 },
413 	{ "mcp4131-503", MCP413x_503 },
414 	{ "mcp4131-104", MCP413x_104 },
415 	{ "mcp4132-502", MCP413x_502 },
416 	{ "mcp4132-103", MCP413x_103 },
417 	{ "mcp4132-503", MCP413x_503 },
418 	{ "mcp4132-104", MCP413x_104 },
419 	{ "mcp4141-502", MCP414x_502 },
420 	{ "mcp4141-103", MCP414x_103 },
421 	{ "mcp4141-503", MCP414x_503 },
422 	{ "mcp4141-104", MCP414x_104 },
423 	{ "mcp4142-502", MCP414x_502 },
424 	{ "mcp4142-103", MCP414x_103 },
425 	{ "mcp4142-503", MCP414x_503 },
426 	{ "mcp4142-104", MCP414x_104 },
427 	{ "mcp4151-502", MCP415x_502 },
428 	{ "mcp4151-103", MCP415x_103 },
429 	{ "mcp4151-503", MCP415x_503 },
430 	{ "mcp4151-104", MCP415x_104 },
431 	{ "mcp4152-502", MCP415x_502 },
432 	{ "mcp4152-103", MCP415x_103 },
433 	{ "mcp4152-503", MCP415x_503 },
434 	{ "mcp4152-104", MCP415x_104 },
435 	{ "mcp4161-502", MCP416x_502 },
436 	{ "mcp4161-103", MCP416x_103 },
437 	{ "mcp4161-503", MCP416x_503 },
438 	{ "mcp4161-104", MCP416x_104 },
439 	{ "mcp4162-502", MCP416x_502 },
440 	{ "mcp4162-103", MCP416x_103 },
441 	{ "mcp4162-503", MCP416x_503 },
442 	{ "mcp4162-104", MCP416x_104 },
443 	{ "mcp4231-502", MCP423x_502 },
444 	{ "mcp4231-103", MCP423x_103 },
445 	{ "mcp4231-503", MCP423x_503 },
446 	{ "mcp4231-104", MCP423x_104 },
447 	{ "mcp4232-502", MCP423x_502 },
448 	{ "mcp4232-103", MCP423x_103 },
449 	{ "mcp4232-503", MCP423x_503 },
450 	{ "mcp4232-104", MCP423x_104 },
451 	{ "mcp4241-502", MCP424x_502 },
452 	{ "mcp4241-103", MCP424x_103 },
453 	{ "mcp4241-503", MCP424x_503 },
454 	{ "mcp4241-104", MCP424x_104 },
455 	{ "mcp4242-502", MCP424x_502 },
456 	{ "mcp4242-103", MCP424x_103 },
457 	{ "mcp4242-503", MCP424x_503 },
458 	{ "mcp4242-104", MCP424x_104 },
459 	{ "mcp4251-502", MCP425x_502 },
460 	{ "mcp4251-103", MCP425x_103 },
461 	{ "mcp4251-503", MCP425x_503 },
462 	{ "mcp4251-104", MCP425x_104 },
463 	{ "mcp4252-502", MCP425x_502 },
464 	{ "mcp4252-103", MCP425x_103 },
465 	{ "mcp4252-503", MCP425x_503 },
466 	{ "mcp4252-104", MCP425x_104 },
467 	{ "mcp4261-502", MCP426x_502 },
468 	{ "mcp4261-103", MCP426x_103 },
469 	{ "mcp4261-503", MCP426x_503 },
470 	{ "mcp4261-104", MCP426x_104 },
471 	{ "mcp4262-502", MCP426x_502 },
472 	{ "mcp4262-103", MCP426x_103 },
473 	{ "mcp4262-503", MCP426x_503 },
474 	{ "mcp4262-104", MCP426x_104 },
475 	{}
476 };
477 MODULE_DEVICE_TABLE(spi, mcp4131_id);
478 
479 static struct spi_driver mcp4131_driver = {
480 	.driver = {
481 		.name	= "mcp4131",
482 		.of_match_table = mcp4131_dt_ids,
483 	},
484 	.probe		= mcp4131_probe,
485 	.id_table	= mcp4131_id,
486 };
487 
488 module_spi_driver(mcp4131_driver);
489 
490 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
491 MODULE_DESCRIPTION("MCP4131 digital potentiometer");
492 MODULE_LICENSE("GPL v2");
493