1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Support for Microchip MCP4728
4 *
5 * Copyright (C) 2023 Andrea Collamati <andrea.collamati@gmail.com>
6 *
7 * Based on mcp4725 by Peter Meerwald <pmeerw@pmeerw.net>
8 *
9 * Driver for the Microchip I2C 12-bit digital-to-analog quad channels
10 * converter (DAC).
11 *
12 * (7-bit I2C slave address 0x60, the three LSBs can be configured in
13 * hardware)
14 */
15
16 #include <linux/bitfield.h>
17 #include <linux/delay.h>
18 #include <linux/err.h>
19 #include <linux/i2c.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/sysfs.h>
22 #include <linux/module.h>
23 #include <linux/property.h>
24 #include <linux/regulator/consumer.h>
25
26 #define MCP4728_RESOLUTION 12
27 #define MCP4728_N_CHANNELS 4
28
29 #define MCP4728_CMD_MASK GENMASK(7, 3)
30 #define MCP4728_CHSEL_MASK GENMASK(2, 1)
31 #define MCP4728_UDAC_MASK BIT(0)
32
33 #define MCP4728_VREF_MASK BIT(7)
34 #define MCP4728_PDMODE_MASK GENMASK(6, 5)
35 #define MCP4728_GAIN_MASK BIT(4)
36
37 #define MCP4728_DAC_H_MASK GENMASK(3, 0)
38 #define MCP4728_DAC_L_MASK GENMASK(7, 0)
39
40 #define MCP4728_RDY_MASK BIT(7)
41
42 #define MCP4728_MW_CMD 0x08 /* Multiwrite Command */
43 #define MCP4728_SW_CMD 0x0A /* Sequential Write Command with EEPROM */
44
45 #define MCP4728_READ_RESPONSE_LEN (MCP4728_N_CHANNELS * 3 * 2)
46 #define MCP4728_WRITE_EEPROM_LEN (1 + MCP4728_N_CHANNELS * 2)
47
48 enum vref_mode {
49 MCP4728_VREF_EXTERNAL_VDD = 0,
50 MCP4728_VREF_INTERNAL_2048mV = 1,
51 };
52
53 enum gain_mode {
54 MCP4728_GAIN_X1 = 0,
55 MCP4728_GAIN_X2 = 1,
56 };
57
58 enum iio_powerdown_mode {
59 MCP4728_IIO_1K,
60 MCP4728_IIO_100K,
61 MCP4728_IIO_500K,
62 };
63
64 struct mcp4728_channel_data {
65 enum vref_mode ref_mode;
66 enum iio_powerdown_mode pd_mode;
67 enum gain_mode g_mode;
68 u16 dac_value;
69 };
70
71 /* MCP4728 Full Scale Ranges
72 * the device available ranges are
73 * - VREF = VDD FSR = from 0.0V to VDD
74 * - VREF = Internal Gain = 1 FSR = from 0.0V to VREF
75 * - VREF = Internal Gain = 2 FSR = from 0.0V to 2*VREF
76 */
77 enum mcp4728_scale {
78 MCP4728_SCALE_VDD,
79 MCP4728_SCALE_VINT_NO_GAIN,
80 MCP4728_SCALE_VINT_GAIN_X2,
81 MCP4728_N_SCALES
82 };
83
84 struct mcp4728_data {
85 struct i2c_client *client;
86 bool powerdown;
87 int scales_avail[MCP4728_N_SCALES * 2];
88 struct mcp4728_channel_data chdata[MCP4728_N_CHANNELS];
89 };
90
91 #define MCP4728_CHAN(chan) { \
92 .type = IIO_VOLTAGE, \
93 .output = 1, \
94 .indexed = 1, \
95 .channel = chan, \
96 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
97 BIT(IIO_CHAN_INFO_SCALE), \
98 .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE), \
99 .ext_info = mcp4728_ext_info, \
100 }
101
102 static int mcp4728_suspend(struct device *dev);
103 static int mcp4728_resume(struct device *dev);
104
mcp4728_store_eeprom(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)105 static ssize_t mcp4728_store_eeprom(struct device *dev,
106 struct device_attribute *attr,
107 const char *buf, size_t len)
108 {
109 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
110 struct mcp4728_data *data = iio_priv(indio_dev);
111 u8 outbuf[MCP4728_WRITE_EEPROM_LEN];
112 int tries = 20;
113 u8 inbuf[3];
114 bool state;
115 int ret;
116 unsigned int i;
117
118 ret = kstrtobool(buf, &state);
119 if (ret < 0)
120 return ret;
121
122 if (!state)
123 return 0;
124
125 outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_SW_CMD);
126
127 for (i = 0; i < MCP4728_N_CHANNELS; i++) {
128 struct mcp4728_channel_data *ch = &data->chdata[i];
129 int offset = 1 + i * 2;
130
131 outbuf[offset] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);
132
133 if (data->powerdown) {
134 u8 mcp4728_pd_mode = ch->pd_mode + 1;
135
136 outbuf[offset] |= FIELD_PREP(MCP4728_PDMODE_MASK,
137 mcp4728_pd_mode);
138 }
139
140 outbuf[offset] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
141 outbuf[offset] |=
142 FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
143 outbuf[offset + 1] =
144 FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);
145 }
146
147 ret = i2c_master_send(data->client, outbuf, MCP4728_WRITE_EEPROM_LEN);
148 if (ret < 0)
149 return ret;
150 else if (ret != MCP4728_WRITE_EEPROM_LEN)
151 return -EIO;
152
153 /* wait RDY signal for write complete, takes up to 50ms */
154 while (tries--) {
155 msleep(20);
156 ret = i2c_master_recv(data->client, inbuf, 3);
157 if (ret < 0)
158 return ret;
159 else if (ret != 3)
160 return -EIO;
161
162 if (FIELD_GET(MCP4728_RDY_MASK, inbuf[0]))
163 break;
164 }
165
166 if (tries < 0) {
167 dev_err(&data->client->dev, "%s failed, incomplete\n",
168 __func__);
169 return -EIO;
170 }
171 return len;
172 }
173
174 static IIO_DEVICE_ATTR(store_eeprom, 0200, NULL, mcp4728_store_eeprom, 0);
175
176 static struct attribute *mcp4728_attributes[] = {
177 &iio_dev_attr_store_eeprom.dev_attr.attr,
178 NULL,
179 };
180
181 static const struct attribute_group mcp4728_attribute_group = {
182 .attrs = mcp4728_attributes,
183 };
184
mcp4728_program_channel_cfg(int channel,struct iio_dev * indio_dev)185 static int mcp4728_program_channel_cfg(int channel, struct iio_dev *indio_dev)
186 {
187 struct mcp4728_data *data = iio_priv(indio_dev);
188 struct mcp4728_channel_data *ch = &data->chdata[channel];
189 u8 outbuf[3];
190 int ret;
191
192 outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_MW_CMD);
193 outbuf[0] |= FIELD_PREP(MCP4728_CHSEL_MASK, channel);
194 outbuf[0] |= FIELD_PREP(MCP4728_UDAC_MASK, 0);
195
196 outbuf[1] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);
197
198 if (data->powerdown)
199 outbuf[1] |= FIELD_PREP(MCP4728_PDMODE_MASK, ch->pd_mode + 1);
200
201 outbuf[1] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
202 outbuf[1] |= FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
203 outbuf[2] = FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);
204
205 ret = i2c_master_send(data->client, outbuf, 3);
206 if (ret < 0)
207 return ret;
208 else if (ret != 3)
209 return -EIO;
210
211 return 0;
212 }
213
214 static const char *const mcp4728_powerdown_modes[] = { "1kohm_to_gnd",
215 "100kohm_to_gnd",
216 "500kohm_to_gnd" };
217
mcp4728_get_powerdown_mode(struct iio_dev * indio_dev,const struct iio_chan_spec * chan)218 static int mcp4728_get_powerdown_mode(struct iio_dev *indio_dev,
219 const struct iio_chan_spec *chan)
220 {
221 struct mcp4728_data *data = iio_priv(indio_dev);
222
223 return data->chdata[chan->channel].pd_mode;
224 }
225
mcp4728_set_powerdown_mode(struct iio_dev * indio_dev,const struct iio_chan_spec * chan,unsigned int mode)226 static int mcp4728_set_powerdown_mode(struct iio_dev *indio_dev,
227 const struct iio_chan_spec *chan,
228 unsigned int mode)
229 {
230 struct mcp4728_data *data = iio_priv(indio_dev);
231
232 data->chdata[chan->channel].pd_mode = mode;
233
234 return 0;
235 }
236
mcp4728_read_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,char * buf)237 static ssize_t mcp4728_read_powerdown(struct iio_dev *indio_dev,
238 uintptr_t private,
239 const struct iio_chan_spec *chan,
240 char *buf)
241 {
242 struct mcp4728_data *data = iio_priv(indio_dev);
243
244 return sysfs_emit(buf, "%d\n", data->powerdown);
245 }
246
mcp4728_write_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,const char * buf,size_t len)247 static ssize_t mcp4728_write_powerdown(struct iio_dev *indio_dev,
248 uintptr_t private,
249 const struct iio_chan_spec *chan,
250 const char *buf, size_t len)
251 {
252 struct mcp4728_data *data = iio_priv(indio_dev);
253 bool state;
254 int ret;
255
256 ret = kstrtobool(buf, &state);
257 if (ret)
258 return ret;
259
260 if (state)
261 ret = mcp4728_suspend(&data->client->dev);
262 else
263 ret = mcp4728_resume(&data->client->dev);
264
265 if (ret < 0)
266 return ret;
267
268 return len;
269 }
270
271 static const struct iio_enum mcp4728_powerdown_mode_enum = {
272 .items = mcp4728_powerdown_modes,
273 .num_items = ARRAY_SIZE(mcp4728_powerdown_modes),
274 .get = mcp4728_get_powerdown_mode,
275 .set = mcp4728_set_powerdown_mode,
276 };
277
278 static const struct iio_chan_spec_ext_info mcp4728_ext_info[] = {
279 {
280 .name = "powerdown",
281 .read = mcp4728_read_powerdown,
282 .write = mcp4728_write_powerdown,
283 .shared = IIO_SEPARATE,
284 },
285 IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4728_powerdown_mode_enum),
286 IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE,
287 &mcp4728_powerdown_mode_enum),
288 { }
289 };
290
291 static const struct iio_chan_spec mcp4728_channels[MCP4728_N_CHANNELS] = {
292 MCP4728_CHAN(0),
293 MCP4728_CHAN(1),
294 MCP4728_CHAN(2),
295 MCP4728_CHAN(3),
296 };
297
mcp4728_get_scale_avail(enum mcp4728_scale scale,struct mcp4728_data * data,int * val,int * val2)298 static void mcp4728_get_scale_avail(enum mcp4728_scale scale,
299 struct mcp4728_data *data, int *val,
300 int *val2)
301 {
302 *val = data->scales_avail[scale * 2];
303 *val2 = data->scales_avail[scale * 2 + 1];
304 }
305
mcp4728_get_scale(int channel,struct mcp4728_data * data,int * val,int * val2)306 static void mcp4728_get_scale(int channel, struct mcp4728_data *data, int *val,
307 int *val2)
308 {
309 int ref_mode = data->chdata[channel].ref_mode;
310 int g_mode = data->chdata[channel].g_mode;
311
312 if (ref_mode == MCP4728_VREF_EXTERNAL_VDD) {
313 mcp4728_get_scale_avail(MCP4728_SCALE_VDD, data, val, val2);
314 } else {
315 if (g_mode == MCP4728_GAIN_X1) {
316 mcp4728_get_scale_avail(MCP4728_SCALE_VINT_NO_GAIN,
317 data, val, val2);
318 } else {
319 mcp4728_get_scale_avail(MCP4728_SCALE_VINT_GAIN_X2,
320 data, val, val2);
321 }
322 }
323 }
324
mcp4728_find_matching_scale(struct mcp4728_data * data,int val,int val2)325 static int mcp4728_find_matching_scale(struct mcp4728_data *data, int val,
326 int val2)
327 {
328 for (int i = 0; i < MCP4728_N_SCALES; i++) {
329 if (data->scales_avail[i * 2] == val &&
330 data->scales_avail[i * 2 + 1] == val2)
331 return i;
332 }
333 return -EINVAL;
334 }
335
mcp4728_set_scale(int channel,struct mcp4728_data * data,int val,int val2)336 static int mcp4728_set_scale(int channel, struct mcp4728_data *data, int val,
337 int val2)
338 {
339 int scale = mcp4728_find_matching_scale(data, val, val2);
340
341 if (scale < 0)
342 return scale;
343
344 switch (scale) {
345 case MCP4728_SCALE_VDD:
346 data->chdata[channel].ref_mode = MCP4728_VREF_EXTERNAL_VDD;
347 return 0;
348 case MCP4728_SCALE_VINT_NO_GAIN:
349 data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
350 data->chdata[channel].g_mode = MCP4728_GAIN_X1;
351 return 0;
352 case MCP4728_SCALE_VINT_GAIN_X2:
353 data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
354 data->chdata[channel].g_mode = MCP4728_GAIN_X2;
355 return 0;
356 default:
357 return -EINVAL;
358 }
359 }
360
mcp4728_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)361 static int mcp4728_read_raw(struct iio_dev *indio_dev,
362 struct iio_chan_spec const *chan, int *val,
363 int *val2, long mask)
364 {
365 struct mcp4728_data *data = iio_priv(indio_dev);
366
367 switch (mask) {
368 case IIO_CHAN_INFO_RAW:
369 *val = data->chdata[chan->channel].dac_value;
370 return IIO_VAL_INT;
371 case IIO_CHAN_INFO_SCALE:
372 mcp4728_get_scale(chan->channel, data, val, val2);
373 return IIO_VAL_INT_PLUS_MICRO;
374 }
375 return -EINVAL;
376 }
377
mcp4728_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)378 static int mcp4728_write_raw(struct iio_dev *indio_dev,
379 struct iio_chan_spec const *chan, int val,
380 int val2, long mask)
381 {
382 struct mcp4728_data *data = iio_priv(indio_dev);
383 int ret;
384
385 switch (mask) {
386 case IIO_CHAN_INFO_RAW:
387 if (val < 0 || val > GENMASK(MCP4728_RESOLUTION - 1, 0))
388 return -EINVAL;
389 data->chdata[chan->channel].dac_value = val;
390 return mcp4728_program_channel_cfg(chan->channel, indio_dev);
391 case IIO_CHAN_INFO_SCALE:
392 ret = mcp4728_set_scale(chan->channel, data, val, val2);
393 if (ret)
394 return ret;
395
396 return mcp4728_program_channel_cfg(chan->channel, indio_dev);
397 default:
398 return -EINVAL;
399 }
400 }
401
mcp4728_init_scale_avail(enum mcp4728_scale scale,int vref_mv,struct mcp4728_data * data)402 static void mcp4728_init_scale_avail(enum mcp4728_scale scale, int vref_mv,
403 struct mcp4728_data *data)
404 {
405 s64 tmp;
406 int value_micro;
407 int value_int;
408
409 tmp = (s64)vref_mv * 1000000LL >> MCP4728_RESOLUTION;
410 value_int = div_s64_rem(tmp, 1000000LL, &value_micro);
411
412 data->scales_avail[scale * 2] = value_int;
413 data->scales_avail[scale * 2 + 1] = value_micro;
414 }
415
mcp4728_init_scales_avail(struct mcp4728_data * data,int vdd_mv)416 static int mcp4728_init_scales_avail(struct mcp4728_data *data, int vdd_mv)
417 {
418 mcp4728_init_scale_avail(MCP4728_SCALE_VDD, vdd_mv, data);
419 mcp4728_init_scale_avail(MCP4728_SCALE_VINT_NO_GAIN, 2048, data);
420 mcp4728_init_scale_avail(MCP4728_SCALE_VINT_GAIN_X2, 4096, data);
421
422 return 0;
423 }
424
mcp4728_read_avail(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,const int ** vals,int * type,int * length,long info)425 static int mcp4728_read_avail(struct iio_dev *indio_dev,
426 struct iio_chan_spec const *chan,
427 const int **vals, int *type, int *length,
428 long info)
429 {
430 struct mcp4728_data *data = iio_priv(indio_dev);
431
432 switch (info) {
433 case IIO_CHAN_INFO_SCALE:
434 *type = IIO_VAL_INT_PLUS_MICRO;
435
436 switch (chan->type) {
437 case IIO_VOLTAGE:
438 *vals = data->scales_avail;
439 *length = MCP4728_N_SCALES * 2;
440 return IIO_AVAIL_LIST;
441 default:
442 return -EINVAL;
443 }
444 default:
445 return -EINVAL;
446 }
447 }
448
449 static const struct iio_info mcp4728_info = {
450 .read_raw = mcp4728_read_raw,
451 .write_raw = mcp4728_write_raw,
452 .read_avail = &mcp4728_read_avail,
453 .attrs = &mcp4728_attribute_group,
454 };
455
mcp4728_suspend(struct device * dev)456 static int mcp4728_suspend(struct device *dev)
457 {
458 struct iio_dev *indio_dev = dev_get_drvdata(dev);
459 struct mcp4728_data *data = iio_priv(indio_dev);
460 unsigned int i;
461
462 data->powerdown = true;
463
464 for (i = 0; i < MCP4728_N_CHANNELS; i++) {
465 int err = mcp4728_program_channel_cfg(i, indio_dev);
466
467 if (err)
468 return err;
469 }
470 return 0;
471 }
472
mcp4728_resume(struct device * dev)473 static int mcp4728_resume(struct device *dev)
474 {
475 struct iio_dev *indio_dev = dev_get_drvdata(dev);
476 struct mcp4728_data *data = iio_priv(indio_dev);
477 int err = 0;
478 unsigned int i;
479
480 data->powerdown = false;
481
482 for (i = 0; i < MCP4728_N_CHANNELS; i++) {
483 int ret = mcp4728_program_channel_cfg(i, indio_dev);
484
485 if (ret)
486 err = ret;
487 }
488 return err;
489 }
490
491 static DEFINE_SIMPLE_DEV_PM_OPS(mcp4728_pm_ops, mcp4728_suspend,
492 mcp4728_resume);
493
mcp4728_init_channels_data(struct mcp4728_data * data)494 static int mcp4728_init_channels_data(struct mcp4728_data *data)
495 {
496 u8 inbuf[MCP4728_READ_RESPONSE_LEN];
497 int ret;
498 unsigned int i;
499
500 ret = i2c_master_recv(data->client, inbuf, MCP4728_READ_RESPONSE_LEN);
501 if (ret < 0) {
502 return dev_err_probe(&data->client->dev, ret,
503 "failed to read mcp4728 conf.\n");
504 } else if (ret != MCP4728_READ_RESPONSE_LEN) {
505 return dev_err_probe(&data->client->dev, -EIO,
506 "failed to read mcp4728 conf. Wrong Response Len ret=%d\n",
507 ret);
508 }
509
510 for (i = 0; i < MCP4728_N_CHANNELS; i++) {
511 struct mcp4728_channel_data *ch = &data->chdata[i];
512 u8 r2 = inbuf[i * 6 + 1];
513 u8 r3 = inbuf[i * 6 + 2];
514
515 ch->dac_value = FIELD_GET(MCP4728_DAC_H_MASK, r2) << 8 |
516 FIELD_GET(MCP4728_DAC_L_MASK, r3);
517 ch->ref_mode = FIELD_GET(MCP4728_VREF_MASK, r2);
518 ch->pd_mode = FIELD_GET(MCP4728_PDMODE_MASK, r2);
519 ch->g_mode = FIELD_GET(MCP4728_GAIN_MASK, r2);
520 }
521
522 return 0;
523 }
524
mcp4728_probe(struct i2c_client * client)525 static int mcp4728_probe(struct i2c_client *client)
526 {
527 const struct i2c_device_id *id = i2c_client_get_device_id(client);
528 struct mcp4728_data *data;
529 struct iio_dev *indio_dev;
530 int ret, vdd_mv;
531
532 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
533 if (!indio_dev)
534 return -ENOMEM;
535
536 data = iio_priv(indio_dev);
537 i2c_set_clientdata(client, indio_dev);
538 data->client = client;
539
540 ret = devm_regulator_get_enable_read_voltage(&client->dev, "vdd");
541 if (ret < 0)
542 return ret;
543
544 vdd_mv = ret / 1000;
545
546 /*
547 * MCP4728 has internal EEPROM that save each channel boot
548 * configuration. It means that device configuration is unknown to the
549 * driver at kernel boot. mcp4728_init_channels_data() reads back DAC
550 * settings and stores them in data structure.
551 */
552 ret = mcp4728_init_channels_data(data);
553 if (ret) {
554 return dev_err_probe(&client->dev, ret,
555 "failed to read mcp4728 current configuration\n");
556 }
557
558 ret = mcp4728_init_scales_avail(data, vdd_mv);
559 if (ret) {
560 return dev_err_probe(&client->dev, ret,
561 "failed to init scales\n");
562 }
563
564 indio_dev->name = id->name;
565 indio_dev->info = &mcp4728_info;
566 indio_dev->channels = mcp4728_channels;
567 indio_dev->num_channels = MCP4728_N_CHANNELS;
568 indio_dev->modes = INDIO_DIRECT_MODE;
569
570 return devm_iio_device_register(&client->dev, indio_dev);
571 }
572
573 static const struct i2c_device_id mcp4728_id[] = {
574 { .name = "mcp4728" },
575 { }
576 };
577 MODULE_DEVICE_TABLE(i2c, mcp4728_id);
578
579 static const struct of_device_id mcp4728_of_match[] = {
580 { .compatible = "microchip,mcp4728" },
581 { }
582 };
583 MODULE_DEVICE_TABLE(of, mcp4728_of_match);
584
585 static struct i2c_driver mcp4728_driver = {
586 .driver = {
587 .name = "mcp4728",
588 .of_match_table = mcp4728_of_match,
589 .pm = pm_sleep_ptr(&mcp4728_pm_ops),
590 },
591 .probe = mcp4728_probe,
592 .id_table = mcp4728_id,
593 };
594 module_i2c_driver(mcp4728_driver);
595
596 MODULE_AUTHOR("Andrea Collamati <andrea.collamati@gmail.com>");
597 MODULE_DESCRIPTION("MCP4728 12-bit DAC");
598 MODULE_LICENSE("GPL");
599